Energy Assessment - ConocoPhilips.pdf

Originator: COPICOPI Group Owner: UO – Engineering – Onshore SumatraArea: GeneralLocation: GeneralSystem: General SystemDocument Type: Final ReportDiscipline / Sub discipline:Old COPI Document No.: -

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Document Title: Final ReportENERGY MANAGEMENT ASSESSMENT / AUDIT FOR PSC CORRIDOR (SUBAN-GRISSIK-RAWA)

COPI Doc No.:

1 IFR 14 Dec 07 Issued for Review

2 IFR 14 Jan 08 Issued for Review

Rev Status Issue Date Reason for Issue Prepared CheckedApprovals

Final Report ID-N-GN-00000-00000-00068 Energy Management Audit / Assessment for PSC CorridorConocoPhillips Indonesia Page 2 of 109

Revision Sheet

REVISION DATE DESCRIPTION OF CHANGE

1 14 Dec 07 Issued for Review

2 14 Jan 08 Issued for Review

ConocoPhillips Indonesia Inc. LtdPT.E M I (Persero)


CONTENTS

I. INTRODUCTION

II. METHODOLOGY

2.1 METHODOLOGY OF ENERGY ASSESSMENT

2.2 METHODOLOGY OF CALCULATION

2.2.1 CALCULATION OF EQUIPMENT

2.2.2 CALCULATION OF SYSTEM

III. ENERGY ASSESSMENT AT SUBAN GAS PLANT

3.1. GENERAL PLANT OPERATION AND PERFORMANCE

3.3.1. GENERAL PLANT OPERATION OF SUBAN GAS PLANT

3.3.2. GENERAL PLANT PERFORMANCE OF SUBAN GAS PLANT

3.2. PERFORMANCE EVALUATION EACH SYSTEM

3.2.1. SEPARATION & COOLER SYSTEM

3.2.2. AMINE SYSTEM

3.2.3. CONDENSATE STABILIZING SYSTEM

3.2.4. DEW POINT CONTROL AND REFRIGERATION SYSTEM

3.2.5. GAS COMPRESSION SYSTEM

3.2.6. GAS TURBINE GENERATOR

3.2.7. AIR COMPRESSOR

3.2.8. ELECTRICAL MAP SUBAN GAS PLANT

3.3. FINDINGS AND RECOMMENDATIONS

IV. ENERGY ASSESSMENT AT GRISSIK CENTRAL GAS PLANT


4.1.1. GENERAL PLANT OPERATION OF GRISSIK GAS PLANT

4.1.2. GENERAL PLANT PERFORMANCE OF GRISSIK GAS PLANT


4.2.1. GAS PRETREATMENT AND MEMBRANE SYSTEM

4.2.2. AMINE SYSTEM

4.2.3. REFRIGERATION SYSTEM



4.2.5. DEHYDRATION SYSTEM

4.2.6. WASTE HEAT BOILER



4.2.9. ELECTRICAL MAP CENTRAL GRISSIK GAS PLANT


V. ENERGY ASSESSMENT AT RAWA OIL PLANT


5.2. PERFORMANCE EVALUATION

5.2.1. GENERAL PERFORMANCE5.2.2. PERFORMANCE EVALUATION OF MAIN EQUIPMENT


VI. PERFORMANCE MONITORING INDICATOR

6.1. EQUIPMENTS

6.1.1. Fired Heater

6.1.2. Waste Heat Boiler

6.1.3. Gas Turbine Generator

6.1.4. Residue Gas Compressor

6.1.5. Air Compressor

6.1.6. Propane compressor

6.1.7. Pumps

6.1.8. Air Cooler

6.1.9. Heat Exchanger

6.2. SYSTEM

6.2.1. Gas Pretreatment

6.2.2. Membrane System

6.2.3. Amine System

Amine Contactor

Amine Regenerator

6.2.4. Dehydration System

6.2.5. Dew Point Control System


Gas Chiller

Low Temperature Separator

6.2.6. Condensate Stabilizer

6.2.7. Depropanizer

APPENDICES

1. SCHEDULE OF ENERGY ASSESSMENT/AUDIT

2. MEASUREMENT DATA

3. LABORATORY ANALYSIS

4. LIST OF DATA HAS BEEN COLLECTED

5. SPREAD SHEET OF EFFICIENCY AND ENERGY CONSUMPTION EQUIPMENTS

SUBAN GAS PLANT

GRISSIK CENTRAL GAS PLANT

RAWA OIL PLANT

6. SPREAD SHEET OF PERFORMANCE MONITORING INDICATOR

EQUIPMENTS

SYSTEMS

7. SIMULATION RESULT OF SUBAN GAS PLANT

8. SIMULATION RESULT OF GRISSIK CENTRAL GAS PLANT


I. INTRODUCTION

As a part of energy management program, in the year of 2007 the Indonesia Business Unit of ConocoPhillips committed to develop plan regarding various efforts to conserve sources and to reutilize waste, energy utilization and to reduce emission reduction for each operating asset. Since 2004, emission level forecasts were generated as part of environmental performance report that shall be further followed up in actual action plans. This assessment is intended to guide the company in identifying energy-related business opportunities and appropriate methods and developing the strategic framework for realizing them. By performing this assessment / audit, it could also find emission reduction opportunities in onshore operating asset.

The aim of this assessment is to identify where and how much energy is used in a facility and for determining energy saving and emission reduction opportunities in onshore operating asset.

The objectives of this assessment / audit are as followed;

1. Provide clear direction or appropriate method as to potential inherent in a strategic approach to energy planning and management.

2. Define specific facilities that consume high energy and generate high emission.

3. To observe and evaluate the present situation of those plants in regards with energy consumption, process efficiency or performance and emission reduction opportunities.

4. Provide options based on a set of criteria (measures) and select the most promising options for implementation.

5. Provide recommendations and action plans in order to reduce energy consumption, increase plant efficiency and reduce emission rate in onshore operating assets by implementing energy diversification, energy efficiency and optimization and possibility to reuse energy waste.

The Scope of this assessment / audit are as followed;,

1 Preliminary Energy Audit / Assessment which includes : Review and prepare additional information, Identification and inventory energy consumption and production data; Analyze data to determine which equipment will get high priority to be assessed and; prepare action plan to perform energy management audit / assessment

2 Performing Energy Audit / Assessment which includes : Identifies area of high energy usage and where energy waste occurs; Develop priorities for reducing energy waste and emission; Provides a criteria of measures which improvements could be implemented and; Generate spreadsheet for energy consumption per equipment


3 Establish Calculation Performance Monitoring Indicators per equipment and system

4 Provide Recommendation for Improvements a part of COPI energy management program

To achieve the targets and to establish interactive cooperation of involved personnel without disturbing surveyed objects routine activities, the procedure of the Energy Assessment / Audit at Suban Gas Plant, Grisik Central Gas Plant and Rawa Oil Plant are as follows:

Preparation of the plant survey,

Field inspection and data collection,

Data verification (of the data collected)

Discussion

Data analysis and evaluation

Preliminary report,

Discussion

Field verification

Interim Report/Draft Final Report

Presentation,

Final Report.

The preparation of the plant survey has been held on 10 – 21 September 2007. The activity are includes define the boundaries, define data to be collected, define instruments / meter related to the data to be collected and prepare checklist for interview.

The Field inspection and data collection has been held on 24 September – 5 October 2007. The activity are includes collection of technical data of main energy-consuming equipment, operation data, historical data, interview data, and direct measurement with portable equipment. Principally, the data collected should be enogh to calculate material and heat balance in each equipment.

During data collecting period at Suban Gas Plant, Grissik Central Gas Plant and Rawa Oil Plant, not all the data requirement for analysis has been collected. Some of the data are completed from COPI Office Jakarta and the other data are completed during 2nd field inspection. Direct measurement are done for all fired heater at Suban Gas Plant and Waste Heat Boiler at Grissik Central Gas Plant.

In order to crosscheck the data gathered are accurate and reliable before carrying out analyses, it is need to do the data verification. The data verification, has been held on 8 - 10 October 2007 and the discussion regarding the result of data verification has been held on 23 October 2007.

Data analysis and evaluation has been held on 22 October – 23 November 2007. The activity of the analysis are includes preparation of calculation methodology, spread


sheet of equipment, develop heat and material balance, performance evaluation, identification/quantification of heat loss and calculation of energy conservation opportunities. The result of data analysis and evaluation are reported in the Preliminary Report on 26 November 2007 and discussion regarding this report has been held on 29 – 30 November 2007.

2nd field survey has been held on 3 – 7 December 2007 at Suban and Grissik. The activity during 2nd field survey are includes :

Measurement of flue gas composition and temperature of Heater and Waste Heat Boiler.

Electrical data records for rotating equipments.

Presentation of draft final report has been held on 18-19 December 2007

The Schedule of Energy Assessment, data has been collected and measured, laboratory analysis are summarized in the appendices no.1 – no. 4.


II. METHODOLOGY

2.1. METHODOLOGY OF ENERGY ASSESSMENT/AUDIT

Obviously, the Methodology of Energy Assessment / Audit at Suban Gas Plant, Grisik Gas Plant and Rawa Oil Plant will involve :

Collect and Analyze Energy-Usage Data

Review, identify and inventory energy consumption data

Identify the main energy consumption system and equipments

Performance evaluation and identify the main energy consumption equipment.

Quantity energy waste and emission.

Recommendation.

The information regarding plant operation has been collected during data collection period from 24 September to 5 October 2007.

The data will be used in the analysis are include;

Daily Log Sheets

Computer logged data (for Suban and Grissik)

Laboratory analysis

Direct measurement during plant survey

Design data

After all the data has been collected, It is need to develop mass balance of each unit in order to verify the accuracy of flow meter reading. If there are discrepancy between mass inlet and outlet, ones of the mass flow should be adjusted, and than the data that has been verified will be used as data basis for development of heat and mass balance each equipment and system.

By using Spreadsheet and Process Simulation, a plant model will be created to calculate performance aspect of the equipments and compare with design or available references.

The plant model spreadsheet is constructed based on material and energy balance each equipment, energy efficiency and losses. Process Simulation used to develop material and energy balance for overall process gas plant.

Especially on the fired heater and waste heat boiler the spreadsheet is constructed based on the calculation of energy efficiency, losses and emission level of each equipment. Based on the data that has been collected, performance of each equipment, efficiency level, energy waste and emission reduction potential of equipment will be calculated and quantified.


Based on the energy and emission reduction potential level of each equipment and refer to technical and financial criteria, recommendation for improvement measure will be identified.

All of the results of the evaluation / analysis will be discuss, present and reported to ConocoPhillips.

The reporting of energy assessment / audit wil include preliminary report, interim/draft final report and final report.

The preliminary report which covers : energy audit methodology, all data collected, all formula for calculations and preliminary findings.

The interim/draft final report which covers : energy audit methodology, all data collected, energy performance analysis result, quantity of all energy waste and emission, energy waste and emission reduction opportunities and performance monitoring system.

The final report which contains of: executive summary, evaluation result during audit / assessment, spreadsheet of energy consumption, spreadsheet of performance monitoring indicators and detail recommendation report.

2.2. METHODOLOGY OF CALCULATION

The methodology of calculation are developed in two model which includes the calculation of equipment and the calculation of process system.

The Calculation of Equipment are includes : Fired Heater; Waste Heat Boiler; Gas Turbine Generator; Residual Compressor; Air Compressor; Propane Compressor; Pumps; Air Cooler; Heat Exchanger .

The Calculation of Process system are includes : Separation system; Amine System; Dehydration System; Condensate Stabilizer System, Depropanizer System and Refrigeration System

All of the calculation are explained regarding the efficiency and performance of each equipment and process system.

2.2.1. CALCULATION OF EQUIPMENTS

2.2.1.a. Fired Heater

The biggest energy consumption in the operation of gas plant is fired heater, so the evaluation of fired heater especially the efficiency and performance are very important in this assessment.


Efficiency of Fired Heater can be calculated in two ways ie. :

Direct Method

Heat Loss Method *

* Refer to Enercon Handbook

a. Direct Method :

The step of calculation are as follows,

Calculate heat duty of fired heater, k cal/hr

Calculate LHV of fuel gas (refer to lab test), kcal/hr

heat duty of fired heater

Efficiency = X 100% LHV of fuel gas

b. Heat Loss Method

Fired Heater Efficiency are calculated based on the heat loss of :

dry flue gas

H2O from combustion of H2

H2O moisture from fuel gas

H2O moisture from air

radiation and convection (refer to design)

%O2, T stack

T out

Fluid Flow

T in

Ta(ambient air temp)

FIRED HEATER

AIR

FUEL

Proc Fluid

Rad.Conv. Flue Gas

Proc Fluid


The step of calculation of heat loss method in the fired heater are as follows,

a. Measure Ta, Tstack and % O2 in flue gas

b. Calculate combustion air for stoichiometry condition

c. Calculate excess air at % O2 as measure

d. Calculate flue gas flow, kg/h (flue gas flow = fuel + comb air stoch + excess air)

e. Calculate flue gas loss, kcal/hr (flue gas loss = flue gas flow x Cp x (Tst – Ta))

LHV of Flue Gas – flue gas loss – Rad & Conv Loss**

Efficiency = X 100% LHV of Fuel Gas

** Refer to design condition

The efficiency calculated from heat loss method can be used to check the accuracy of fuel gas flow meter recorded at each fired heater. The step of calculation are as follows :

calculate heat duty of fired heater based on the different enthalpy of BFW (steam) inlet and outlet.

calculate the heat release of fired heater based on the calculated efficiency (ie. the heat duty divided by efficiency).

heat release from the calculation can be used to check the accuracy of fuel gas flow meter recorded at each fired heater

2.2.1.b. Waste Heat Boiler (WHB)

The calculation methodology of WHB is similar with fired heater, the small different is in the calculation of steam flow which is calculated based on BFW flow rate minus blow down flow rate.

Efficiency of Waste Heat Boiler also can be calculated in two ways ie. :

Direct Method

Heat Loss Method *

* Refer to Enercon Handbook

a. Direct Method

(Hst – HBFW) x ST.FlowEfficiency = X 100%

L.H.V. (Fuel Gas + Pem Gas + Acid Gas)


b. Heat Loss Method

The step of calculation are as follows,

a. Measure Ta, T stack and % O2 in flue gas

b. Calculate combustion air of acid gas, permeate gas and fuel gas for stochiometry condition

c. Calculate excess air at actual condition

d. Calculate dry flue gas flow at actual conditions, kg/hr

e. Calculate total loss, kcal/hr

Total loss = dry flue gas loss + blow down loss + rad & conv. loss

Dry flue gas = flue gas flow x Cp x (Tst – Ta)

Blow down loss = % blow down *x ST. Flow x ( H Saturate – HBFW)

*Assume % blow down (± 2%)

** Refer to design condition

LHV (Total) – Total loss

Efficiency = X 100% LHV (Total)

Ta (ambient air temp)

Flow, P, Tsteam

% O2 , Tstack

WASTE HEAT BOILER

Rad.Conv. Flue Gas

Steam

AIR

Fuel Gas

Water

Acid Gas

Permeat Gas

Blow Down


2.2.1.c. Gas Turbine Generator

GTG

AIR

FUEL

Flue GasConvRad.

BHP G ELECTR

IC

kWh x 860.1 x 3.968

Efficiency = X 100% LHV Fuel Gas x Flow F.G (Btu/h)

LHV Fuel Gas x Flow Fuel Gas

Performance = kWh

Efficiency of Gas Turbine also can be calculated by using heat loss method, which include heat loss of :

dry flue gas





2.2.1.d. Residual Gas Compressor

Fuel gas input

Energy loss

compressor

Mechanical work derived from pressure


Mechanical workEfficiency = Heat from fuel gas input

Z R T n Pd n-1Mechanical Work * = Q x x x ( ( ) n - 1 ) / (33,000 x 0.77)

MW n – 1 Ps

Q = Gas Flow, lb / mntR = Gas ConstantMW = Molecular weightT = inlet Temperature, oRZ = Compressibility Factorn = Polytropic FactorPd = Discharge PressurePs = Suction Pressure

* Refer to Pipeline Handbook

Efficiency of Gas Turbine also can be calculated by using heat loss methode, which include heat loss of :

dry flue gas





2.2.1.e. Air compressor

Mechanical workEfficiency =

Electric power input

1.4 Ps Q Pd 0.4 O x 10.000 Mechanical Work * = x x ( ( )1.4 - 1 ) x

0.4 6120 Ps 0.8 x 0.95


Energy loss



Ps = Inlet Press Kgf/ cm2

Q = Air Flow m3 / mntR = Press ratio P2 / P1O = Factor ( 1.0 – 1.5 )

* Refer to Energy Conservation Handbook – ECC Japan

2.2.1.f. Propane compressor

Mechanical workEfficiency = Heat from fuel gas input

Z R T n Pd n-1Mechanical Work * = Q x x x ( ( ) n - 1 ) / (33,000 x 0.77)

MW n – 1 Ps

Q = Gas Flow, lb / mntR = Gas ConstantMW = Molecular weightT = inlet Temperature, oRZ = Compressibility Factorn = Polytropic FactorPd = Discharge PressurePs = Suction Pressure

* Refer to Pipeline Handbook


Energy loss



2.2.1.g. Gas Chiller

Cooling Load* = (GF x Cp g (To – Ti)) + (CF x Cpc (To – Ti)) + (f x CF x Latent Heat)

Cooling Load

COP Actual* = compressor motor power (actual)

Cp g = Specific Heat gas at P & T operationGF = Gas FlowCF = Condensate FlowCp c = Specific Heat condensate f = fraction of condensate

* Refer to ASHRAE Handbook (fundamentals)

2.2.1.h. Pumps

Mechanical workEfficiency =


Energy loss

Electric power inputMechanical work (capacity, total head)

Obtained from curves into data sheet

Gas Chiller

From Gas to Gas HE To PropaneCompressor

From Propane AcumulatorLow Temperatur

Separator

ToH1

H2T1

Gas

PropaneTo


Mechanical Work (Pw) *:

Ht (psia) = Dp – Sp

Sp = Suction pressure (psia)Dp = Discharge pressure (psia)

Ht (feet) = 2.31 x Ht (psia)

* Refer to Pump Handbook - Karrasik, Krutzsch

2.2.1.i. Air cooler

Efficiency = Cooling Load Electric power input

Cooling Load = Q

Q = m (H)Where

m : Flow rate

H : Enthalpy different

Fouling Factor Performance are calculated based on the value of Overall heat transfer coefficient (Uo):

Uo = Q / (A Tlm)

Q : actual heat load (Q act)

A : Heat transfer Area

Sg = Specific grafity

Ht = Total Head (feet)

Fv = Correction factor related to viscousity

Pw (hp) = fv.(Sg x Ht) / 3960

T in h

T in l

T out l

T out h


Energy loss

m, p


Tlm : Log Mean Temperature Different

2.2.1.j. Heat Exchanger

Evaluation of heat exchanger are include the performance of heat transfer coefficient compare to design condition. If the heat transfer coefficient are lower it is could be caused by fouling or there are change in quality or quantity in the process side.

VAP. OUT VAP. OUT

VENT

LIQ. OUT VAP. IN VAP. IN CONDENSATE OUT

STEAM IN

a. Performance Calculation:

Performance = [Heat load based on actual data calculation]

[Heat load based on basic design calculation]

= Q act / Q design

b. Fouling Factor Performance are calculated based on the value of Overall heat transfer coefficient (Uo):

Uo = Q / (A Tlm)

Q : actual heat load (Q act)

A : Heat transfer Area

Tlm : Log Mean Temperature Different


2.2.2. CALCULATION OF SYSTEMS

2.2.2.a. Separation System

a. TSA UNIT

FEED GAS

TREATED GAS

ADSORBTIONCOLUMN

Adsorption Rate = (mole C6+ Feed - mole C6+ Treated) (lbmole/lbmole)

Mole C6+ Feed

TSA Regeneration Rate = BTU (BTU/lbmole)

(mole C6+ Feed - mole C6+ Treated)

b. Membrane Unit

MEMBRANEFEED GAS

PROCESS GAS

PERMEATE GAS

Membrane separation rate = mole CO2 in Permeate Gas (lbmole/ lbmole)

Mole CO2 in Feed Gas

HC Slipped rate = mole HC in Permeate Gas (lbmole/ lb mole)

Mole HC in Feed Gas


2.2.2.b. Amine System

a. Amine Contactor

FEED GAS

RICH AMINE

AMINECONTACTOR

LEANAMINE

TREATED GAS

Absorbtion Rate = ``mole-CO2 absorbed (lbmole/lbmole) and (lb/lb)

Mole pure lean amine

Mole Weight of pure Lean Amine are dynamic should be calculated

b. Amine Regenerator

AMINEREGENERATOR

RICH AMINE

ACID GAS

LEAN AMINE

STEAM

CONDENSATE

Amine Regeneration Rate = BTU(steam) (BTU/lbmole -CO2)

CO2 removed


2.2.2.c. Dehydration System

DEHYDRATIONPACKAGE

TREATED GAS

GAS

WATER VAPOR OUT

GLYCOLCYCLE

GLYCOL MAKE-UP

FUEL GASCONSUMPTION

Absorbtion Rate = lbs-H2O absorbed (lbmole/GPM) and (Lb-H2O/Lb-Glycol)

GPM Pure Lean Glycol

Glycol Regeneration Rate = BTU (Fuel Gas) (BTU/lb –H2O)

Moisture removed

2.2.2.d. Condensate Stabilizer

CONDENSATE STABILIZATION

FEED LIQUID

LP FUEL GAS

CONDENSATE

STEAM

STEAM CONDENSATE

LIGHTHC

MOISTURE OUT


Yield of Stabilization = BBL Treated Condensate (bbl/ bbl)

BBL Raw Condensate

Quantity total of condensate refer to percentage of feed inlet

Stabilizer Performance = BTU(steam) (BTU/ bbl)

BBL Treated Condensate flow

2.2.2.e. Depropanizer

DEPROPANIZER

FEED LIQUID

CONDENSATEPRODUCT

PROPANE PRODUCT

Yield of Stabilization = mole Propane product (lbmole/ lbmole)

Mole Feed HC

Deprop. Performance = kWh(Electric) (kWh/ lbmol)

Lbmole Propane product


III. ENERGY ASSESSMENT AT SUBAN GAS PLANT


3.1.1. GENERAL PLANT OPERATION OF SUBAN GAS PLANT

Gas from well head is delivered to CGP with flow line about 1 km length to the separation unit, HP Production Separator. Because gas produced from HP Production Separator still contain CO2, H2S and H2O in high concentration, it has to be treated by CO2/H2S Removal Package and Dehydration Unit to meet the gas delivery condition requirements.

A selective Amine based on MDEA solvent shall be provided for removal of CO2 & H2S in feed gas from Gas Scrubber, to meet the sales gas specification. The system shall also include the regeneration of the MDEA solvent used to absorb H2S.

Acid Gas Removal Unit is installed with capacity 700 MMSCFD (total 4 trains) Sour Gas and should be removed CO2 / H2S until meet sales gas specification (3%). Acid gas released from Acid Gas Removal unit should be routed to The treated gas scrubber Unit with enough pressure approximately 1400 psig to ensure Acid Gas have enough pressure for next processes.

A Ethylene Glycol based gas dehydration unit shall be provided to dehydrate gas from amine unit to achieve the sales gas specification (5-7 Lb/SCF). EG Dehydration Unit is with capacity 700 MMSCFD (Total 4 trains).

The treated gas will be compressed by GTC (Gas To Compressor) with capacity 235 MMSCFD (There are 4 GTC, each of GTC has 235 MMSCFD Capacity) to increase sales gas pressure until 1280 psig. The other part of treated gas is delivered to Fuel Gas Filter as Fuel Gas for Gas Turbine Generator (GTG),Gas Turbine Compressor or as fuel gas for the CPP gas engine equipment.

The Condensate from Horizontal Separator is routed to Stabilizer Feed Drum for further separation process from carry over gas. To meet the Condensate Delivery Condition, the condensate produced is stabilized with Condensate Stabilization Units, with capacity are 44,349 Lb/hr for train 1 & 82,211 Lb/hr for train 2, and then stored in the Condensate Storage Tank with capacity is 30,000 BBL. The condensate pumps will be used to dispatch the condensate to Condensate Truck Loading.

Water collect from separation unit is automatically drained to a common header and then to be processed in the produced water treatment system.

Blow down system is used for over pressure protection or for reducing the CGP pressure either in emergency (ESD) or at the operator’s discretion in a shutdown and blocked condition. The blow down system shall be capable of relieving the entire CPP


Gas to Flare

Acid Gas

Sales Gas

Suban Gas Well Gas Seperation Unit Amine System TEG Dehydration Unit Residual Compressor

Condensate

Condensate Stabilizer

Liquid water

T T1 T2 3

4

T 5 6T

7

8 T

9

10

11

equipments from the highest possible shut-in pressure down to half times in 15 minutes. The blow down system is arranged with automatic blow down valves which is fitted at the downstream of the separation units and at the discharge of CNG Compressor to blow down through the HP Flare vent line.Localized venting of gas to atmosphere is also provided for piping and vessels via manual vents and pressure relieving devices, i.e. relief valves.

Fire water will be supplied from the fire water make up pump to a Fire Water Pond. Fire water is distributed to the fire water main ring by three fire water pumps (two pumps act as main pumps, and one as jockey) in a duty standby arrangement. Foam tank and foam pump are provided to protect the condensate storage tank. The CGP shall be fully equipped with fire and gas detection system.

All electric instruments shall be hard-wired to CGP Control Room and communicated to Programmable Logic Control (PLC) and Human Machine Interface (HMI) to monitor and control the process.

The simple process flow of Suban field is shown with block diagram in figure 2.1

Figure 3.1. Simple Block Diagram

Gas from Inlet Separator still contains CO2 and H2O in high concentration. The gas shall be treated in purification unit before the gas is delivered to Grissik Central Gas Processing plant by Pipe line system.

3.1.2. GENERAL PLANT PERFORMANCE OF SUBAN GAS PLANT

The Energy source of Suban Gas Plant actually are fuel gas from Scrubber which is consumed by GTG, GTC and Fired Heater (thermal oxidizer, amine re-boiler heater and heat medium heater).

Based on 29 September 2007, the fuel gas consumption for each equipment are shown in table below;


Table 3-1 : Fuel gas consumption

Fuel Gas to Flare

248-FQI-2131B D 0.200 MMSCFD

248-FQI-2231B D 1.000 MMSCFD

TOTAL C 1.200 MMSCFD

Fuel Gas to Heater

Thermal Oxidixer

225-H-102 D 0.314 MMSCFD

225-H-202 D 0.161 MMSCFD

0.475 MMSCFD

Amine Reb Heater

225-H-111 D 0.620 MMSCFD

225-H-211 D 0.563 MMSCFD

1.183 MMSCFD

Heat Medium Heater

257-H-101A D 0.121 MMSCFD

257-H-101B D 0.016 MMSCFD

257-H-201A D 0.152 MMSCFD

257-H-201B D 0.138 MMSCFD

C 0.428 MMSCFD

Fuel gas to GTG

247-GT-101A -

247-GT-101B -

247-GT-201A C 0.900 MMSCFD

247-GT-201B C 0.900 MMSCFD

247-GT-201C C 0.900 MMSCFD

D 2.700 MMSCFD

Fuel gas to GTC

242-KT-101 D 0.590 MMSCFD

242-KT-201 D - MMSCFD

242-KT-301 D 0.730 MMSCFD

242-KT-401 D 0.700 MMSCFD

C 1.430 MMSCFDTOTAL - 2

C 6.22 MMSCFD


TOTALC 7.42 MMSCFD

Note : D = Data ; C = Calculated

The total fuel consumption at 29 September 2007 (including fuel gas to flare) is 7.42 MMSCFD. There are two type of fuel gas used in Suban Gas Plant ie. : LP Fuel gas and HP Fuel gas. LP Fuel gas is used to fired heater and HP Fuel gas is used to GTG and GTC. The heating value (HHV) of LP Fuel gas is around 1,574 Btu/SCF and HP Fuel Gas is around 1,130 Btu/SCF.

Based on the heat balance calculation of Fired Heater, GTG and GTC, the energy picture on 29 September 2007 which are includes Heat Release, Heat Absorb, Heat Loss and CO2 emission are as follows :

Table 3-2 : The energy picture of Suban Gas Plant

HEAT RELEASE,

Btu/hr

HEAT ABSORB,

Btu/hr

STACK LOSS, Btu/hr

TEMP, Deg F

CO2 Emission,

lb/hr

FLARE

248-FQI-2131B 13,200,110 0 11,898,856 1,472 1,849

248-FQI-2231B 66,000,552 0 59,494,279 1,472 9,243

HEATER

Thermal Oxidizer

225-H-102 38,486,293 0 35,495,414 932 81,738

225-H-202 10,602,175 0 8,303,983 2,012 1,488

Amine Reboiler H-M Heater

225-H-111 40,771,370 32,203,736 9,055,361 405 5,730

225-H-211 37,035,660 29,160,613 8,988,198 361 5,204

Heat Medium Heater

257-H-101A 8,017,576 5,448,456 2,338,395 486 1,123

257-H-101B 0 0 0 0 0

257-H-201A 10,004,765 7,479,528 2,322,751 543 1,405

257-H-201B 9,088,243 6,758,329 2,473,720 500 1,275

GTG

247-GT-101A 0 0 0 0 0

247-GT-101B 0 0 0 0 0

247-GT-201A 42,371,386 7,714,245 33,163,974 916 5,611


247-GT-201B 42,371,386 7,721,419 29,310,275 921 5,611

247-GT-201C 42,371,386 7,702,911 29,397,944 925 5,611

GTC

242-K-101 28,157,031 4,816,837 21,555,786 1,213 1,668

242-K-201 0 0 0 0 0

242-K-301 34,800,050 7,277,193 22,755,271 1,261 2,064

242-K-401 33,379,354 6,924,878 21,806,787 1,237 1,979

TOTAL 456,657,336 123,208,143 298,360,993 689 131,598

Plant Performance :

The production rate at 29 September 2007 is 94,023 BOE which include 517 MMSCFD of sales gas (note : 1 SCF = 6000 BOE) and 7,823 barrel of condensate, and total heat released including flare gas is 456,657,336 Btu/hr. The performance of Suban Gas Plant as shown in table below :

Table 3-3 : Suban Gas Plant performance

PRODUCTION RATESales Gas = 517.20 MMSCFD

= 86,200.00 BOE

Condensate = 7,823.00 BOE

Total Prod => 94,023.00 BOE

ENERGY CONSUMEExcluding Flare 377,456,674.27Including Flare 456,657,336.12 Btu/hr

ENERGY INTENSITYExcluding Flare 4,014.51 Btu/BOEIncluding Flare 4,856.87 Btu/BOE

It shown that the energy consumption to produce one BOE (= Energy Intensity) at Suban Gas Plant is 4,014.51 Btu/BOE (Excluding Flare) or 4,856 Btu/BOE (including flare) . (Note : No design data to compare the Actual Energy Intensity).


This condition can not compare with another gas plant, because every plant have its own characteristic. The important thing is how to reduce energy consumption based on its own characteristic.

3.2 PERFORMANCE EVALUATION EACH SYSTEM

3.2.1 SEPARATION & COOLER SYSTEM

A. DESCRIPTION

Gas from manifold enters the Inlet Separator which will separate gas from the bulk liquid. The separator are designed for gas flow 160 MMSCFD (for train 1,2) and 214 MMSCFD (for train 3,4), whereas liquid flow are designed about 1973 gallon/min ( for train 1,2) and 2640 gallon/min (for train 3,4) . Production Separator will be normally operated at pressure 1188 psig and temperature 240 °F.

The Inlet Separator is a three phase separator to provide primary gas-condensate-water separation. This is to ensure that no significant carry-over/under of the respective phases.

B. PERFORMANCE

Main equipment of Separation and cooler system are include : Inlet Cooler 215-E-101A/B, 215-E-201A/B, 215-E-401A/B and 215-E-301A/B. The performance of main equipment are as follows.

Table 3-4 : Performance of Inlet Cooler

215-E-101 215-E-201 215-E-301 215-E-401 DESIGN

INLET GAS COOLER

Temp inlet, F 220.00 218.00 220.00 220.00 240.00

Temp outlet, F 110.00 110.00 110.00 110.00 115.00

Flowrate, lb/hr 323,297 323,297 486,956 486,956 476,174

AIR COOLANT

Temp inlet, F 93.20 93.20 93.20 93.20 95.00

Temp outlet, F 113.00 113.00 114.00 114.00 131.60

Delta T LMTD 45.96 45.96 46.54 46.54 52.30

HEAT DUTY, MMBtu/hr 28.37 28.37 43.04 43.04 50.01

HEAT TRANSFER RATE, BTU/HR.FT2.F

4.46 4.46 3.08 3.08 5.09


ELECTRIC CONSUMPTION, KW

13.13 13.13 13.13 13.13 16.41

ACTUAL FAN OPERATED 4.00 4.00 4.00 4.00 4.00

CALCULATE FAN OPERATED

3.04 3.04 3.44 3.44 4.00

The above table shows that the actual heat duty of each inlet cooler are less than design. It means that the actual cooling rate needs less energy than design. The heat duty on Train #1 and #2 are operated at 60% of design.

The heat transfer rates of exchangers are closed to the design. Based on actual condition, the performance of cooler is still in good condition.

Losses at inlet cooler are described from cooler outlet temperature. If the outlet temperature higher than the design outlet temperature, it means the cooling rate is not good. At this case, the exchangers are still in good condition.

3.2.2 AMINE SYSTEM

A. DESCRIPTION

The feed gas from Inlet Separator contains CO2 5.42% by mole and small of H2S content. A typical feed condition is 114 oF and 1163 psia; The products specifications is designed for the CO2 content is 3.4 % by mole respectively. The acid gas removal package uses activated methyl-di ethanolamine (MDEA) to remove the acid gases (H2S & CO2) by means of counter-current mass transfer in an Amine Contactor unit.

The gas from the inlet separator will be fed to the Acid Gas Removal Package. As the inlet gas is a saturated gas stream, there is a possibility of hydrocarbon and water condensation prior to inlet of the amine contactor. To minimise liquid carry-over to the system, a Horizontal filter unit is provided. The horizontal filter unit will have level control drain-off valves, both on the upstream and downstream of the filter element, whereby the liquid is sent to the flare system for disposal.

The liquid free gas from the Horizontal filter is then fed to the Amine Contactor, whereby the gas is in contact with lean aqueous MDEA solution (amine). The enhanced solubility of the acid gas in lean amine would soluble the acid gas component, thus stripping it of H2S and CO2.

The rich amine from the contactors flows to the rich amine flash drums. The rich amine flows under level/flow control through the lean/rich amine exchangers where it is heated to about 206 oF by heat exchange with the hot lean amine from the two regenerators. The rich amine feeds the regenerator above the stripping section which contains stainless steel structured packing. CO2 and H2S are stripped from the rich solution by heat produced in the regenerator re-boilers.


B. PERFORMANCE

Main equipment of Amine System are includes :

Amine Heat Medium Heater (225-H-111; 225-H-211); Amine Reg. Reboiler (225-E-102 A/B, 225-E-202 A/B); Treated Gas Cooler (225-E-105, 225-E -205, 225-E -305, 225-E -405), Amine Charge Pump (225-P-102A/B/C), Amine Booster Pump (225-P-101A/B/C) and Amine Heat Medium Circ. Pump (225-P-111A/B/C, 211A/B/C).

The performance of main equipment of Amine System are as follows.

Amine Heat Medium Heater :

Table 3-5 : Performance of Amine Heat Medium Heater

225-H-111 225-H-211 DESIGN

FUEL,

Flow, MMSCFD 0.62 0.56 1.13

FLUE GAS

T out, F 404.60 361.40 412.00

O2, % 6.50 9.20 3.00

Excess Air, % 41.00 83.15 15.27

HOT WATER

lb/hr 2,285,233 2,004,973 2,910,000

T in, F 257 257 285

T out, F 270 270 305

P in, Psi 280 280 285

P out, Psi 270 270 274

PERFORMANCE

Heat absorption (LHV), MMBtu/hr

31.81 28.70 57.98

Heat absorption (HHV), MMBtu/hr

32.20 28.94 58.12

Efficiency (LHV), % 85.80 84.87 89.11

Efficiency (HHV), % 78.95 78.06 81.18

CO2 EMISSION

CO2 Emission from fuel gas, lb/hr

5,730 5,203 10,609

The heat duty of Amine H-M Heater was only 55 % and 50 % load compare to design condition.


The efficiency by using heat loss method are calculated based on the flue gas composition and temperature measurement by using portable analyzer and thermometer. No meter of temperature and O2 analyzer in flue gas line.

The flue gas temperature at actual condition is lower than design condition but the excess air is too high and the operating load is too low. The efficiency at actual condition is around 85 % compare to design condition which is 89 %. This efficiency is low compare to design condition, it is caused by higher excess air and lower operating load.

Amine Regenerator Reboiler:

Table 3-6 : Performance of Amine Regenerator Reboiler

225-E-102A/B 225-E-202A/B DESIGN

HEAT MEDIUM SIDE (TUBE)

Pressure, psig 280.00 8.70 235.00

Temp. inlet (F) 275.00 278 305.00

Temp. outlet (F) 250.00 250 285.00

Flowrate Heat Medium, Lb/hr 1,025,912 894,957 1,412,550

AMINE SIDE (SHELL)

Temp. inlet Regenerator, F 212.00 205 249.1

Temp. outlet Regenerator, F 220.00 240 254.3

Delta T LMTD 45.98 41.40 42.88

HEAT DUTY, Btu/hr 26,313,323 25,711,215 29,084,405

HEAT TRANSFER RATE SERVICE, BTU/HR.FT2.degF

85 93 101

The above table shows that the heat duty operated closed to the design. The difference between actual heat duty and design only 10%. The operated temperature higher than design value.

The performance of heat exchanger can be evaluated from the value of overall heat transfer rate (U). The U at actual condition is 85 BTU/(Hr/Ft2.F) and 93 BTU/(Hr/Ft2.F) compare to design value which is 101 BTU/(Hr/Ft2.F..


Treated Gas Cooler :

Table 3-7 : Performance of Treated Gas Cooler

225-E-105 225-E-205 DESIGN

WATER+ACID GAS

Pressure,psig 1206 1202 1162

Temp inlet, F 147.90 152.00 139.80

Temp outlet, F 120.70 125.70 120.00

Flowrateof Acid gas, MMSCFD 138.92 119.56 151.80

AIR COOLANT

Temp inlet, F 92.00 92.00 95.00

Temp outlet, F 110.00 112.00 118.40

Delta T LMTD 33.09 36.76 26.50

HEAT DUTY, Btu/hr 4,622,698 3,873,942 4,300,000

ELECTRIC CONSUMPTION, KW 56.79 55.61 59.68

ACTUAL FAN OPERATED 2 2 2

CALCULATE FAN OPERATED 2.1 1.8 2.0


3.9 3.0 5.2

225-E-305 225-E-405 DESIGN

WATER+ACID GAS

Pressure,psig 1206 OFF 1162

Temp inlet, F 147.90 OFF 139.80

Temp outlet, F 126.50 OFF 120.00

Flowrateof Acid gas, MMSCFD 204.82 OFF 203.40

AIR COOLANT



Delta T LMTD 33.09 OFF 26.5/23

HEAT DUTY, Btu/hr 5,346,317 OFF 5,810,000


ELECTRIC CONSUMPTION, KW 59.15 OFF 59.68

ACTUAL FAN OPERATED 2 OFF 2

CALCULATE FAN OPERATED 1.9 OFF 2.0


4.5 OFF 5.4

The above table shows that the actual heat duty closed to the design. The difference between actual and design only +/- 10%. Electric power consumption for motor fan drivers also close to design with deviance not more than 7%. The fan running at actual condition also same as design, each exchanger have 2 (two) fans running. This indicates that the process is in good condition. Temperatures of gas outlet from these exchangers all meet the specification process condition, 120.7 and 125.7 deg F for train#1 and #2, and 126 deg F for train#3 refer to the design is 120 and 203.4 deg F respectively.

The performance of heat exchanger can be evaluated from the value of overall heat transfer rate (U). The U at operating condition give value of 3.9 and 3.0 BTU/(Hr/Ft2.F) for train#1 and train#2 and 4.5 BTU/(Hr/Ft2.F) for train#3. The design value is 5.2 and 5.4 BTU/(Hr/Ft2.F).

Regenerator Reflux Condenser :

Table 3-8 : Performance of Regenerator Reflux Condenser

225-E-101 225-E-201 DESIGN

WATER+ACID GAS

Pressure,psig 11.9 12 26.9

Temp inlet, F 194.40 226.4 205.00

Temp outlet, F 135.60 120.5 120.00

Flowrateof Acid gas, MMSCFD 5.50 7.3 8.76

AIR COOLANT

Temp inlet, F 92.00 92 92.00

Temp outlet, F 140.00 145 144.00

Delta T LMTD 48.80 50.41 48.60

HEAT DUTY, Btu/hr 9,259,749 13,234,590 16,824,662



CALCULATE FAN OPERATED 2.2 3.1 4.0

HEAT TRANSFER RATE, 1.9 2.7 3.0


BTU/HR.FT2.F

The above table shows that regenerator reflux condenser is operated at 55% load for 225-E-101 and 78% load for 225-E-201 compare to design condition. This caused by the flow rate of acid gas are 62% and 83% compare to design condition.

Actual fan operated for the cooler 225-E-101 is 2 fans running, but the calculated fan should be operated is 3 fans (2.2). This causes the temperature of the outlet of cooler is higher than the design. Design value state the temperature is 120 deg F, but this cooler operated at 135 deg F. The outlet temperature of cooler 225-E-201 is meet to the design value.

The U (overall heat transfer rate) at actual condition is 1.9 and 2.7 BTU/(Hr/Ft2.F) for 225-E-101 and 225-E-201 compare to design is 3.0 BTU/(Hr/Ft2.F).

Lean Amine Cooler :

Table 3-9 : Performance of Lean Amine Cooler

225-E-103 225-E-203 DESIGN

LEAN AMINE SIDE

Pressure, psig 135.00 135.00 129.43

Temp inlet, F 180.00 180 182.90

Temp outlet, F 130.00 130 125.00

AIR COOLANT SIDE

Temp inlet, F 94.00 94 95.00

Temp outlet, F 135.00 134 137.20

Delta T LMTD 40.33 40.80 37.30

HEAT DUTY, Btu/hr 16,784,037 16,254,308 31,537,959

ELECTRIC CONSUMPTION, KW

35.35 35.35 76.00

ACTUAL FAN OPERATED 2.00 2.00 4.00

CALCULATE FAN OPERATED

2.1 2.1 4.0

HEAT TRANSFER RATE, BTU/(HR.Ft2.degF)

1.6 1.5 1.8


The above table shows that the actual heat duty of 225-E-103 and 225-E-203 are rated at 50% compare to the design. This caused by the flow rate of lean amine only about 50% - 60% from design capacity.

The flow rate of lean amine affects to the power required of fan cooler driver.

The actual operated fans for 225-E-103 and 225-E-203 are 2 fans compare to 4 fans for design. This condition affects the performance of cooler, especially with heat transfer rate.

The value of U (overall heat transfer rate) at actual condition is 1.6 BTU/(Hr/Ft2.F) for 225-E-103 and 1.5 for 225-E-203 compare to design 1.8 BTU/(Hr/Ft2.. This difference indicated that the performance of coolers are still have good performance.

Rich-Lean Amine Exchanger :

Table 3-10 : Performance of Rich-Lean Amine Exchanger

225-E-104A-B 225-E-204A-B DESIGN

RICH AMINE SIDE

Pressure, psig 90.00 100.00 100.00

Temp inlet, F 105.00 105.00 138.20

Temp outlet, F 190.00 210.00 210.20

Flowrate of Rich Amine, USGPM 458.20 483.40 1,138.90

LEAN AMINE SIDE

Temp inlet, F 250.00 250.00 253.20

Temp outlet, F 210.00 210.00 182.30

Delta T LMTD 80.41 67.35 43.55

HEAT DUTY, Btu/hr 16,403,302 20,960,808 39,616,136

HEAT TRANSFER RATE, BTU/(Hr/Ft2.F)

N/A N/A N/A

The flow rate of fluid in Rich-lean amine exchanger is about 40% from design capacity. This will affect the heat load for these exchangers at 40% for 225-E-103 and 50% for 225-E-203.

LMTD between hot fluid and cold fluid are higher than the design specification. This case will affect the heat transfer rate for these exchangers. The temperature inlet of Rich amine is lower compare to the design value. This is indicate the amine contacting process in the field running on lower temperature than the design specification.


Lean Amine Charge Pump :

Table 3-11 : Performance of Lean Amine Charge Pump

DESCRIPTION UNIT 225-P-102A 225-P-102B 225-P-102C Design

value value value value

specific gravity 1.05 1.05 OFF 1.00

Temperature F 137.00 137.00 OFF 125.00

suction pressure psia 111.00 111.00 OFF N/A

discharge pressure psia 1550.00 1550.00 OFF N/A

flow GPM 265.00 265.00 OFF 1165.00

Total head ft 3180.05 3180.05 OFF 2550.00

Electric motor power HP 575.00 575.00 OFF 1000.00

Mechanical work HP 227.34 227.34 OFF 766.69

Efficiency % 39.54 39.54 OFF 76.67

Two Amine Charge pumps were running at 265 GPM each, and had efficiency of 39.54%. This efficiency is quite low compare with 76.67% efficiency at design condition. This is due to very low flow rate they handled. The 76.67% efficiency can be achieved at 1165 GPM.

The sum of fluid flow rate for each pump (530 GPM) is still far below the design flow rate for one pump. Higher efficiency could be achieved should the fluid flowing is handled by one pump only.

Amine Reboiler H/M Circulation Pump :

Table 3-12 : Performance of Amine Reboiler H/M Circulation Pump

DESCRIPTION UNIT 225-P-111A

225-P-111B

225-P-211A

225-P-211B

Design

specific gravity 1.00 1.00 1.00 1.00 1.00

Temperature F 137.00 137.00 137.00 137.00 285.00

suction pressure psia 205.70 205.70 205.70 205.70 N/A

discharge pressure psia 294.70 294.70 294.70 294.70 N/A

flow GPM 2211.00 2186.00 1911.00 1911.00 3044.00

Total head ft 205.59 205.59 205.59 205.59 180.00


Electric motor power

HP 168.00 168.00 152.00 152.00 190.00

Mechanical work HP 117.31 115.99 101.40 101.40 141.41

KW 87.52 86.53 75.64 75.64 105.49

Efficiency % 69.83 69.04 66.71 66.71 74.43

Two of the three pumps were working to feed Amine re-boiler medium heater, so four pumps worked to serve two Amine re-boiler medium heater. Each circ.-pump (P-111 A/B) worked at 2211 and 2186 GPM, with 69% efficiency and P-211 A/B worked at 1911 GPM, with 66% efficiency. All pumps are operated close to design efficiency.

Lean Amine Booster Pump :

Table 3-13 : Performance of Lean Amine Booster Pump

DESCRIPTION UNIT 225-P-101A 225-P-101B Design

specific gravity 1.05 1.05 1.00

Temperature F 137.00 137.00 125.00

suction pressure psia 16.70 16.70 N/A

discharge pressure psia 131.70 131.70 N/A

flow GPM 225.00 225.00 1430.00

Total head ft 115.00 115.00 244.00

Electric motor power HP 70.00 70.00 122.00

Mechanical work HP 15.43 15.43 90.05

Efficiency % 22.04 22.04 73.81

The worst case was found at Amine booster pumps, the efficiency of P-101-A/B is only 22 %. The production process utilized two of the three pumps to support Lean amine charge pumps. Each of these booster pumps pumping out fluid at 225 GPM.

The sum of fluid flow rate (450 GPM) is still far below the design flow rate for one pump. Higher efficiency could be achieved should the fluid flowing is handled by one pump only.

3.2.3 CONDENSATE STABILIZING SYSTEM

A. DESCRIPTION

Hydrocarbon liquid from inlet separator and LTS are sent to the stabilizer feed drum. Gas from the feed drum is sent under back pressure control to the low pressure fuel gas system.


The hydrocarbon liquid from the feed drum is fed under level control to the top tray of the condensate stabilizer. The stabiliser reboiler is a kettle type shell and tube exchanger utilizing hot water from Medium Heater at operation.

The condensate product from the stabilizer is sent via the HC condensate cooler bundle in the refrigerant condenser air cooled exchanger frame and a kettle type hydrocarbon condenstae cooler by propane refrigerant, gas blanketed, condensate storage tank.

B. PERFORMANCE

Main equipment of Condensate Stabilizing system are includes : Heat medium heater 257-H-101A/B, 257-H-201A/B; Stabilizer Re-boiler 235-E-101A/B, 235-E-201A/B; Condensate Cooler 235-E-102, 235-E-102

Heat Medium Heater :

Table 3-14 : Performance of Heat Medium Heater

257-H-101A DESIGN

FUEL,

Flow, MMSCFD 0.12 0.10

FLUE GAS

T out, F 511.20 629.00

O2, % 13.90 3.00

Excess Air, % 179.07 15.27

HOT WATER

, lb/hr 106,647.53 110,000.00

T in, F 310.00 316.60

T out, F 350.00 360.00

P in, Psi N/A 200.00

P out, Psi N/A 200.00

PERFORMANCE

Heat absorption (LHV), MMBtu/hr 5.34 4.76


5.45 4.76

Efficiency (LHV), % 73.57 83.00

Efficiency (HHV), % 67.94 75.49

CO2 EMISSION

CO2 Emission from fuel gas, lb/hr 1,122.86 937.53


Table 3-14 : Performance of Heat Medium Heater

257-H-201A 257-H-201B DESIGN

FUEL,

Flow, MMSCFD 0.15 0.14 0.17

FLUE GAS

T out, F 568.80 525.60 629.00

O2, % 8.50 10.20 3.00

Excess Air, % 62.20 86.38 15.27

HOT WATER

, lb/hr 228,820.95 180,110.31 164,900.00

T in, F 300.00 300.00 316.6

T out, F 330.00 330.00 360

P in, Psi N/A 225.00 227.5

P out, Psi N/A 210.00 200

PERFORMANCE

Heat absorption (LHV), MMBtu/hr 7.38 6.66 7.94

Heat absorption (HHV), MMBtu/hr 7.48 6.76 8.00

Efficiency (LHV), % 81.18 80.73 84.00

Efficiency (HHV), % 74.76 74.36 76.77

CO2 EMISSION

CO2 Emission from fuel gas, lb/hr 1,404.86 1,275.47 1,552.85

The above table shows that H-101 A, H-201 A and H-201-B are operated close to design condition. The efficiency by using heat loss method are calculated based on the fuel gas heating value, flue gas composition and temperature measurement by using flue gas analyzer.

Flue gas temperature is lower than design condition but the excess air is very high. Calculated Efficiency of 257-101-A is 73 % compare to design is 84 % and the efficiency of 257-201-A/B is around 81 % compare to design is 84 %. The lower efficiency is caused by higher excess air of the heater.


Condensate Stabilizer Re boiler :

Table 3-15 : Performance Condensate Stabilizer Re-boiler

235-E-101 235-E-201 DESIGN

HEAT MEDIUM SIDE (SHELL)

Pressure, psig 180.00 200.00 200.00

Temp. inlet, F 350.00 335.00 350.00

Temp. outlet, F 295.00 300.00 310.00

Flowrate (Heat medium), Lb/hr 39,139.19 57,038.28 n/a

Hydrocarbon Side

Temp Condensate to reboiler, F 278.00 278.00 298.00

Delta T LMTD 34.78 32.93 45.36

HEAT DUTY, Btu/hr 2,214,754 2,053,347 3,000,000

HEAT TRANSFER RATE, (BTU/Hr.Ft2.F) 39.14 38.32 40.65

The above table shows that actual condition of heat duty of 235-E-201 and 235-E-101 is lower than design. The reboiler of 235-E-201 have capacity higher than 235-E-101 but the heat transfer rate are close to design.

Condensate Cooler :

Table 3-16 : Performance Condensate Cooler

235-E-102 235-E-202 DESIGN

CONDENSATE

Temp inlet, F 288.00 288 304.30

Temp outlet, F 106.60 106.5 120.00

Flowrate, GPM 101.89 193.4 287

AIR COOLANT:

Temp inlet, F 92.00 92 95.00

Temp outlet, F 136.00 136 139.90

Delta T LMTD 58.65 58.52 74.00

HEAT DUTY, Btu/hr 1,976,054 3,752,578 7,841,737



1.11 2.12 2.36

ELECTRIC CONSUMPTION **), KW

8.83 9.42 11.00

The above table shows that the condensate cooler have heat duty only 25% for 235-E-102 and 48% for 235-E-202 refer to the design value. This caused by the flow rate of condensate, and LMTD.

The flow rate for 235-E-102 is 35% and 235-E-202 is only 67% refer to the design. LMTD value for cooler 235-E-102 and 235-E-202 are 80% from LMTD design. This affect the value of heat load (Q) of coolers, because the heat load is straight forward with condensate flow rate and LMTD.

The overall heat transfer rate (U) at actual condition is 1.11 BTU/(Hr/Ft2.F) for 235-E-102 and 2.12 BTU/(Hr/Ft2.F for 235-E-202 compare to the design is 2.36BTU/(Hr/Ft2.F).

3.2.4 DEW POINT CONTROL AND REFRIGERATION SYSTEM

A. DESCRIPTION

The propane refrigerant gas from gas chiller via suction scrubber enter the 1st stage propane compressor. The propane refrigerant gas from the 1st compressor discharge and from the economizer goes to the propane compressor 2nd stage than the discharge of 2nd stage goes to the condenser cooler and enter to the accumulator. Propane refrigerant from the accumulator goes to the economizer (flushing).

Propane gas from the economizer enter the suction of 2nd stage compressor and the propane refrigerant enter the gas chiller via propane subcooler. The design flowrate of the 1st stage propane compressor is 38,200 lbs/hr and the 2nd stage of propane compressor is 52,800 lbs/hr.

There are 3 propane compressor driven by electric motor 1300 KW each and via refrigerant header supply refrigerant for 4 gas chillers (1 gas chiller for 1 train). At the actual condition only 2 compressor are in operation.

B. PERFORMANCE

Main equipment at Refrigeration system are includes propane condenser, propane compressor and gas chiller.

Propane Condenser :

Table – 3.17 : Performance of Propane Condenser

230-E-104 DESIGN

PROPANE :


Pressure, psig 250 265

Temp inlet, F 140.00 180.00

Temp outlet, F 119.00 121.00

Flowrate, MMSCFD (gas) 30.00 32.90

AIR COOLANT:

Temp inlet, F 92.00 95.00

Temp outlet *), F 112.00 117.50

Delta T LMTD 27.50 26.30

HEAT DUTY, Btu/hr 19,151,470 25,387,806

ELECTRIC CONSUMPTION **), KW 17.67 22.00

HEAT TRANSFER RATE, BTU/HR.FT2.F 2.59 3.29

The above table shows that actual condition of heat duty of 230-E-104 is 75% compare to design. The heat duty impact on the power required for fan driver which is 80% electric consumption respectively.

The U value (overall heat transfer rate) at actual condition is 2.59 BTU/(Hr/Ft2.F) and 3.29 BTU/(Hr/Ft2.F for the design value.

Entirely, the performance of propane condenser is operated at good condition.

Propane Compressor:

Table – 3.18 : Performance of Propane Compressor

UNITS DESIGN K 101 A K 101 C

PROPANE FLOW ST. 1 38,160.00 30,669.25(calculated)

25,861.64 (calculated)

PROPANE FLOW ST. 2 52,800.00 42,446.24(calculated)

35,792.51(calculated)

ABSL SUCTION PRESSURE ST.1 24.50 24.00 24.00

ABL.DISCHARGE PRESS ST 1 101.00 100.00 100.00

ABSL DICHARGE PRESSURE ST. 2 265.00 260.00 260.00

TOTAL POWER REQUIRED 1,214.78 966.64 815.11

ACTUAL POWER 1,300.00 1,110.00 936.00

COP 1.89


The above table shows that the propane compressor operated at 70-80 % load. The calculated propane flow of stage-1 K-101 A and K-101 C are 30,669 lb/hr and 25,861 lb/hr with the actual power are 1110 KW and 936 KW . The design propane flow of stage-1 is 38,160 lb/hr with the power is 1,300 KW. It means that the propane compressor is still operated at normal conditions.

The design COP of the propane compressor is 1.89. COP at actual condition can not be calculated accurately because no meter for propane flow.

Gas Chiller:

Table – 3.19 : Performance of gas chiller

UNITS DESIGN GAS CHILLER (230-E-

102/201/302/402)

GAS INTAKE TEMP.AT EVAP. DEG F 1.00 16.00

GAS OUTPUT TEMP.AT EVAP. DEG F (10.00) 5.00

SALES GAS FLOW MMCFD 300.00 533.00

CONDENSATE FLOW BBL/D 4,000.00 3,000.00

HEAT RELEASE MMBtu/hr 16.52 11.80

TOTAL POWER KW 2,600.00 1,930.00

C.O.P 1.86 1.79

The above table shows the cooling load of gas chiller is 71 % load and two of propane compressor are operated to handle the refrigeration system.

Performance of each gas chiller can not be calculated, because two propane compressors serve four gas chillers simultaneously. However total performance still can be calculated.

The operating condition of four gas chiller almost similar (T gas inlet = 16 F , T out gas = 5 F). Total COP of gas chiller is 1.79. It’s still close to design condition.

3.2.5 GAS COMPRESSION

A. DESCRIPTION

The pressure of treated gas after Amine System and Refrigeration System is decrease lower than 1000 psig. To meet the pressure requirement of sales gas it needs to compress sales gas by using Residual Gas Compressor. There are 4 gas compressor 2 x 235 MMSCFD and 2 x 300 MMSCFD driven by gas turbine generator. At the actual condition only 3 GTC in operation and 1 GTC standby


B. PERFORMANCE

Main equipment at Gas Compression System are 242-K-101, 242-K-102, 242-K-301 and 242-K-401,

Gas Compressor :

Table – 3.20 : Performance of Gas Compressor

UNITS DESIGN 242-K-301 242-K-401

SALES GAS FLOW ( Q ) MMSCFD 235.00 206.00 206.00

SUCTION PRESSURE PSIA 965.00 915.00 915.00

DISCHARGE PRESSURE PSIA 1,295.00 1,130.00 1,115.00

FUEL CONSUMPTION MMBtu 36.01 28.06 26.36

POWE REQUIRE (POLYTROPIC)

HP 4,537.09 2,835.13 2,651.33

ENERGY INTENSITY Btu/HP 7,936.81 9,896.28 9,940.95

DESIGN 242-K-101 242-K-201

SALES GAS FLOW ( Q ) MMSCFD 10,905.10 150.00 OFF

SUCTION PRESSURE PSIA 955.00 910.00

DISCHARGE PRESSURE PSIA 1,215.00 1,110.00

FUEL CONSUMPTION MMBtu 40.92 20.19

POWE REQUIRE (POLYTROPIC) HP 4,653.97 1,940.43

ENERGY INTENSITY Btu/HP 8,792.49 10,406.28

The above table shows that the compressor are operated at 80 % load compare to design condition.

The Energy Intensity (Btu/HP) of 242-K-101, 242-K-301 and 242-K-401 are higher compare to design value. This condition is caused by the lower operating load of compressors. To know the performance of compressor, it should be compare with design performance of gas turbine compressor (see table below).


Gas Turbine :

Table – 3.21 : Performance of Gas Turbine Compressor

29-Sep-07 DESIGN

242-KT-101 242-KT-201 242-KT-101 /201

A TURBINE

Fuel gas :

flow, MMSCFD 0.59 OFF 1.02

Flue gas :

Temperature, C 1,213 OFF 1,160

O2, % 14 OFF 14

Excess Air, % 191 OFF 185

Eff, % 19 OFF 25

Btu/HP 13,256 OFF 10,115

B COMPRESSOR

Power Required, KW 1,447 OFF 3,471

, HP 1,940 OFF 4,653

29-Sep-07 DESIGN

242-KT-301 242-KT-401 242-KT-301/ 401

A TURBINE

Fuel gas :

flow, MMSCFD 0.73 0.70 1.05

Flue gas :

Temperature, C 1,261 1,237 1,175

O2, % 14 14 14

Excess Air, % 168 174 174

Eff, % 23 23 27

Btu/HP 10,946 11,225 9,401

B COMPRESSOR

Power Required, KW 2,115 1,978 3,409

, HP 2,835 2,651 4,570


In the daily operation, the gas turbines efficiency is around 23 %, these efficiency is less than the design condition (27%). Based on the design performance below, the performance of gas turbine at low load are close to design figure.

DESIGN PERFORMANCE OF GTC K-301/401

POWER, HP5,000.00

4,000.00

3,000.00

2,000.00

1,000.00

BTU/KWH9,400.00 10,000.00 11,000.00 12,500.00 17,000.00

DESIGN PERFORMANCE OF GTC K-101/201

POWER, HP 5,000.00 4,000.00 3,000.00 2,000.00 1,000.00

BTU/KWH 10,100.00 10,700.00 11,600.00 13,200.00

17,000.00

3.2.6 GAS TURBINE GENERATOR

A. DESCRIPTION

Electrical power Generator driven by Gas turbine generator, with the gas supplied from HP (high pressure) fuel gas system. There are 2 GTGs each 1173 KW from Suban phase-1 and 3 GTGs each 5820 KW from Suban phase-2.

The Generator specification are 5820 KW of power, 6600 volt, freq 50 Hz, cos Q 0.85. The large motors (lean amine charge pump, Amne reboiler HM Pump, propane compressor) are supplied by 6600 volt and the other motors using 400 volts.

B. PERFORMANCE

The main equipment of gas turbine generator are 247-GTG-101A/B and 247-GTG-201A/B/C

The performance of GTG are as follow :

Table – 3.22 : Performance of GTG

29-Sep-07 DESIGN

247-GT-201A 247-GT-201B

247-GT-201C

247-GT-201A


TURBINE

Fuel gas :

flow, MMSCFD 0.90 0.9 0.90 1.62

Flue gas :

Temperature, F 916 921 925 946

O2, % 16 16 16 15

Excess Air, % 312 309 308 243

Turbine Eff, % 18.04 18.04 18.01 30

Btu/kwh 16,925 16,926 16,950 11,336

CO2 emission :

Flow, lb/hr 5,611 5,611 5,611 4,446

GENERATOR

Power Output, KW 2,146 2,102 2,178 5,821

PF 0.83 0.83 0.83 0.84

Voltage, V 6,600 6,600 6,600 6,600

Frequency, Hz 50 50 50 50

GTGs are operated less than 40 % load each, total load is around 6,426 KW. This load actually can be handle by two GTGs with 55 % load each. If any disturbanceoccurs, the load shading system will shut off un-priority load, so system black out can be avoided. The low load of GTG caused low efficiency of gas turbine.

The stack temperature of GTG are close to design condition but the calculated efficiency is only 18 % compare to design which is 30 %. The decreasing efficiency is caused by lower operating load which will increased radiation and convection loss.

Compare to the design performance of gas turbine generator (table below) , the performance GTG at low load are still in good condition

Table – 3.23 : Design Performance of GTG

DESIGN PERFORMANCE OF GTG

POWER 5,800 5,000 4,000 3,000 2,000 1,000BTU/KWH 11,340 11,800 12,600 14,300 17,200 25,000


3.2.7 AIR COMPRESSOR

A. DESCRIPTION

Instrument and utility air are supplied by the 1x340 scfm and 1x140 scfm screw type compressor. The compressed air is filtered and then dried in heatless adsorption type dries which are on automatic regeneration cycles. The instrument air compressor packages are provided with local electronic control panels. The instrument air receiver is normally operated between 110 and 120 psig.

B. PERFORMANCE

There are four compressors Atlas Copco GA 37 x 2 and GA 75 x 2 with design capacity is 960 SCFM, the duty of each equipment are as follows,

The performance of air compressor are as follows :

Table 3-24 : Performance of Air Compressor

251-A-101A (ATLAS COPCO GA 75)

DESIGN ACTUAL

POWER 72.60 45.93

COMPRESS AIR FLOW 340.00 266.66

ACTUAL PERFORMANCE 0.20 0.20

251-A-101 B (ATLAS COPCO GA 37)

DESIGN ACTUAL

POWER 44.00 28.27

COMPRESS AIR FLOW 140.00 129.90


The above table shows that the compressor is operated at low load. Actual power of 251-A-101 A is 45.93 KW compare to design 72.6 KW and 251-A-101 B is 28.27 KW compare to design 44 KW.

Actual performance of air compressor calculated by :

(Actual power / Qs x ((Pd/Ps)^0.2857 – 1)) Note : Qs = air flow


225-P-102A/B/CLean Amine Charge pump A/B/C

1130 HP x3

225-EM-101/201 A/B/C/DRegenerator reflux condenser fan

11 KW x8

225-PM-105Amine transfer pump

14.7 HP

225-PM-104Amine sump pump

14.7 HP

215-EM-301/401/A/B 1-2Inlet cooler fan

22 KW x8

225-P-111A/B/CAmine reboiler H/M circ pump A/B/C

185 HP x3

225-P-211A/B/CAmine reboiler H/M circ pump A/B/C

185 HP x3

225-EM-103A/B/C/DLean Amine cooler fan

19 KW x4

225-EM-105/205/305/405 ATreated gas cooler fan

19 KW x4

225-P-102A/B/CLean Amine booster pump A/B/C

112 HP x3

6.6 KV

400 V

225-EM-203A/B/C/DLean Amine cooler fan

19 KW x4

225-EM-105/205/305/405 BTreated gas cooler fan

19 KW x4

400 V

229-PM-302/402/A/BGlycol Injection pump

26.8 HP

400 V

3.2.8 ELECTRICAL MAP SUBAN GAS PLANT

Electrical map is derived from single line diagram, and intend to get a closer and clear point of view to one that need brief description on power consumption at each process. This map is made simple as possible so, it doesn't show how the electric system is distributed. Emphasize is given to voltage, and power required for each equipment. Note that the power mentioned below is the power in normal design condition.

A. Inlet Gas System

B. Amine System

C. Dehydration system

225-PM-103A/BRegenerator reflux pump A/B

3.73 HP x2


3.73 HP x2


230-EM-104 A/B/C/D 1-2Propane condenser fan A-D

22 KW x8

230-K-101-EM1-6L.O. cooler fan propane compr. A/B/C

7.15 KW x6

230-K-101-PM 1-3L.O. pump for propane compr. A/B/C

6.7 HP x3

230-PM-101Depropaniser overhead feed pump

7.1 HP

230-EM-107A/BDepropaniser overhead condenser fan

7.5 KW x2

230-PM-102Depropaniser reflux pump

1.7 HP

230-H-106Depropaniser reboiler heater

106 HP

235-PM-102D/ECondensate shipping pump

40 HP x2

235-EM-202A/BCondensate cooler fan

11 KW x2

235-KM-201Vapoor recovery compr.

29.5 HP

242-EM-301/401 A-DResidue gas compr. After cooler

15 KW x8

251-KM-201 A/BAir compressor A/B

120 HP x2

252-PM-101 C-GWell water lift pump

5.36 HP x5

400 V

6.6 KV

400 V

400 V

400 V

252-PM-105 A/BAmine makeup water pump A/B

15 HP x2

251-A-201N2 generation

30 KW

252-PM-104 A/BPortable water pump

7.4 HP x2

D. Propane Compressor System

E. Depropanizer and Condensate Stabilization System

F. Residue Gas Compressor System

G. Air Compressor, and Utility

230-KM-101 A/B/CPropane compressor A/B/C

1306 KW x3


248-P-101/201 A/BFlare KO drum A

3 HP x8

258-PM-202 A/BProduced water injection pump A/B

60 HP x2

400 V

257-PM-201 A/B/CHeat medium circ. pump A/B/C

49.5 HP x3

H. Flare, and Water handling

3.3 FINDINGS AND RECOMENDATION

1. Instrumentation and Metering

Based on the site survey founded that many metering and instrument are not work properly. Findings and recommendations of metering and instrumentation at Suban Gas Plant are as follows :

Equipments Findings Recommendations

1. Amine Reb H-M Heater

There are inaccurate temperature indicator of circulation Hot Water

Combustion analyzer in each HM Heater not work properly

the oxygen analyzer should be repaired

Need to calibrate meter of hot water temperature indicator

2 H-M Heater No Oxygen analyzer

The calculated efficiency of HM Heater from direct method difference with heat loss method. This discrepancy maybe caused by lack ofaccuracy of Temperature indicator and hot water circulation flow meter.

Need to install oxygen analyzer in order to monitor the performance of this equipment

Need to calibrate temperature indicator and hot water circulation flow meter

3 Gas Turbine Generator

There is no flow meter of fuel gas in each GTG.

Some indicator/sensor of GTGs have no link to DCS in CCR

Need to install fuel gas flow meter and link to DCS

4 Gas Turbine Compressor

lack of accuracy fuel meter

Need to calibrate fuel flow meter and


link to DCS

5 Propane compressor

No power record for propane compressor

Need to implement continues record for propane compressor to evaluate COP

6 Chiller Temperature inlet and outlet gas chiller are inaccurate

need to install temperature indicator inlet and outlet gas chiller for performance evaluation and link to DCS

7 Air compressor

No power meter for air compressor

need to install meter of air compressor for performance evaluation and link to DCS

8 Pumps No power meter for lean amine booster pump

need to install meter of lean amine booster pump for performance evaluation and link to DCS

9 Heat Exchanger

No temperature and pressure indicator at gas-gas exchanger

Temperature indicator of steam at amine Re-boiler are not accurate

Need to install temperature indicator at gas-gas exchanger for performance monitoring

Need to calibrate the steam temperature indicators at amine re-boiler

10 Amine system Temperature indicator between inlet and outlet are not accurate

Recalibration of temperature indicator

11 Electric Distribution

No continue recording for electrical distribution

Need to record electrical distribution (6000 V line) at daily records


2. Heater

Based on the calculation bellows are the efficiency, heat absorb and CO2 emission of fired heater at Suban Gas Plant

EFFICIENCY HEAT DUTY CO2 EMISSION

% MMBtu/hr Lb/hr

AMINE REB H-M HEATER

DESIGN 89.11 57.98 10,609.42

225-H-111 85.80 31.81 5,730.36

225-H-211 84.87 28.70 5,203.54

HEAT MEDIUM HEATER

DESIGN 257 H-101A/B 84.00 4.37 712.53

257-H-101A 73.60 5.35 1,122.86

257-H-101B OFF OFF OFF

DESIGN 257 H-201A/B 84.00 7.94 1,552.85

257-H-201A 81.18 7.38 1,404.86

257-H-201B 80.73 6.66 1,275.47

Finding :

The above tables shows that :

The heat duty of Amine H-M Heater is only 50 % and 44 % load compare to design condition. The Gas Plant are operated at 517 MMSCFD of sales gas or 74 % load compare to design condition. This condition means that the design of fired heater is too large.

Amine H-M Heater is operated at high excess air (44 % and 71 % ) compare to the design figure which is 15 % excess air. This excess air will impact lower efficiency of H-M Heater

HM Heater is operated at high excess air (62 %, 86 % and 179 % ) compare to the design figure which is 15 % excess air. This excess air will impact lower efficiency of Heater (Calculated Efficiency from heat loss method will be around 70 % compare to design is 84 %)

Recommendation :

Design Amine H-M Heater is too large, so the heater can be handle for revamping until 125 % Amine Capacity.


Amine H-M Heater is the main energy consuming equipment in the amine system, so its performance should be monitored daily. Hence, it needs temperature and O2 meters at flue gas line to support the monitoring activity.

Amine H-M Heater should be operated close to the design excess air (15%) to achieve better efficiency,

HM Heater should be operated close to the design excess air (15%) to achieve better efficiency

5. Gas turbine generator

Based on the calculation, bellows are the efficiency, heat rate, BHP and CO2 emission of GTG at Suban Gas Plant:

GAS TURBINE GENERATOR EFFICIENCY HEAT RATE BHP CO2 EMISSION

% BTU/KWH KW Lb/hr

DESIGN 30.43 11,336.00 6,063.54 9,803.22

247-GT-201A 18.04 16,924.65 2,235.42 5,610.65

247-GT-201B 18.06 16,908.92 2,189.58 5,610.65

247-GT-201C 18.01 16,949.55 2,268.75 5,610.65

Finding :

Three GTGs load are low in daily operation ( less then 40%),.the average efficiency is around 18 % (design = 30 %)

Heat rate of three GTGs are around 16.9 MBtu/KWH compare to design 11.3 MBtu/KWH

Recommendation :

To achieve better efficiency, GTGs should be operated at more then 50 % load (two GTGs in operation)

Load shading should be operated properly to sustain two GTGs in operation

6. Gas turbine Compressor

Power require and energy intensity of residue gas compressor are as follows :


COMPRESSOR SALES GAS FLOW,

MMSCFD

POWEREQUIRE, KW

ENERGY INTENSITY, KW

DESIGN 242-K-301 235.00 4,537.09 7,936.81

242-K-301 206.00 2,835.13 9,896.28

242-K-401 206.00 2,651.33 9,940.95

DESIGN 242-K-101 300.00 4,653.97 8,792.49242-K-101 150.00 1,940.43 10,406.28

242-K-102 OFF OFF OFF

Turbine efficiency, heat rate and CO2 emission are as follows :

TURBINE Turbine Eff, Heat Rate CO2 emission :

% Btu/BHP lb/hr

DESIGN 242-KT-301 29.13 7,878.86 5,341.69

242-KT-301 23.53 9,746.77 1,838.04

242-KT-401 23.35 9,942.20 1,753.20

DESIGN 242-KT-101 25.89 8,793.54 6,070.11

242-KT-101 21.78 10,737.29 1,385.60

242-KT-102 OFF OFF OFF

Finding :

Max capacity of KT-401 and KT-301 are 235 MMSCFD each, with suction press 950 psi and discharge 1280 psi

Max capacity of KT-201 and KT-101 are 300 MMSCFD each, with suction press 950 psi and discharge 1200 psi

Actual turbine efficiency of KT-401 and KT-301 is around 23 % and KT-101 is 22 % compare to design efficiency of KT-401 and KT-301 are 29 % and KT-101 is 26 %

Based on the design flow rate, 3 GTCs can handle 770 MMSCF

7. Propane Compressor

Performance of propane compressor are as follows :


PROP COMPRESSOR POWER REQUIRED, KW

ACTUAL POWER, KW

COP

DESIGN 1,214.78 1,300.00 1.89

230-K 101 A 966.64 1,110.00 1.78

230- K 101 C 815.11 936.00 1.78

Finding :

Inlet flow of refrigerant vapor to propane compressors come from one header, so difficult to evaluate COP each compressor.

Design COP of propane compressor is 1.89, calculated COP at actual condition (based on heat absorb) is around 1.78

8. Gas Chiller

Performance of gas chiller are asfollows :

GAS CHILLER UNITS DESIGN EVAPORATOR (102,201,302,402)

GAS INTAKE TEMP.AT EVAP. DEG F 1.00 16.00

GAS OUTPUT TEMP.AT EVAP. DEG F (10.00) 5.00

SALES GAS FLOW MMCFD 300.00 533.00

CONDENSATE FLOW BBL/D 4,000.00 3,000.00

HEAT RELEASE MMBtu/hr 16.52 11.80

TOTAL POWER KW 2,600.00 1,930.00

C.O.P 1.86 1.79

Finding :

Inlet flow of refrigerant to gas chiller come from one header, so difficult to evaluate COP for each gas chiller

Heat duty of four gas chiller is 11.8 MMBTU/hr compare to design is 16.52 MMBTU/hr. The motor power of propane compressor is 2046 kW

Design COP of gas chiller is 1.86, calculated COP at actual condition (based on heat release) is around 1.79


9. Pump

Finding :

Calculated efficiency of pumps are as follows;

PUMPS Flow, GPM Efficiency, %

Actual Design Actual Design

Amine Charge Pump

225-P-102A 265.00 1165.00 39.54 76.67

225-P-102B 265.00 39.54

Amine Booster Pump

225-P-101A 225.00 1430.00 22.04 73.81

225-P-101B 225.00 22.04

Amine Reboiler H/M Circulation Pump

225-P-111A 2211.00 3044.00 69.83 74.43

225-P-111B 2186.00 69.04

225-P-211A 1911.00 66.71

225-P-211B 1911.00 66.71

Amine charge pumps and Amine booster pumps were running in low efficiency. This is due to very low of fluid rate they handled. Should two split of flow that flowing through “Amine booster pumps is merged together to flow through one pump only(530 GPM), its total flow still far below the rate of design (1165 GPM).

The similar case was found at Amine booster pumps. Two pumps were running to handle 225 GPM rate each.

Recommendation :

Higher efficiency could be achieved should the fluid flowing is handled by one pump only (If total rate of flow not exceed flow rate at design).

10. Cooler

Findings :

Calculated of coolers are as below:

No.

COOLER HEAT DUTY HEAT TRANSFER RATE

ELECTRIC/HEAT DUTY

(MMBTU/HR) (BTU/HR.FT2.oF) ( % )


1. Inlet Gas Cooler

215-E-101 28.37 4.46 0.63%

215-E-201 28.37 4.46 0.63%

215-E-301 43.04 3.08 0.42%

215-E-401 43.04 3.08 0.42%

2. Treated Gas Cooler

225-E-105 4.62 3.91 4.19%

225-E-205 3.87 2.95 4.90%

225-E-305 5.35 1.89 3.77%

225-E-405 OFF OFF OFF

3. Regenerator Reflux Condenser

225-E-101 9.26 1.94 0.65%

225-E-201 13.23 2.68 1.03%

4. Lean Amine Cooler

225-E-103 16.78 1.60 0.72%

225-E-203 16.25 1.53 0.74%

5. Condensate Cooler

235-E-102 1.98 1.11 1.53%

235-E-202 3.75 2.12 0.86%

6. Propane Cooler 230-E-104 19.15 2.59 0.31%

Power required to drive motors of fan coolers are below 1% due to their heat duties. This condition indicate that the power consumption of these coolers are in good condition except Treated gas cooler and Condensate cooler.

Recommendations :

Need to check again the performance of Treated gas cooler and Condensate cooler, especially motor driver of fan coolers.

11. Heat Exchanger

Findings :

Calculated of Heat Exchangers are as listed below:

No. HEAT EXCHANGER HEAT DUTY HEAT TRANSFER RATE

DIRTY FACTOR

(MMBTU/HR) (BTU/HR.FT2.oF) ACTUAL DESIGN

1. Stabilizer Reboiler


235-E-101 2.21 39.14 0.0009 0.0010

235-E-201 3.02 48.13 0.0034 0.0010

2. De-C3 Reboiler 230-E-106

0.18 N/A N/A N/A

3. Rich/Lean Amine Exch.

225-E-104A/B 16.40 N/A N/A N/A

225-E-204A/B 20.96 N/A N/A N/A

4. Gas-Gas Exch. 230-E-307

14.00 157.31 0.0023 0.0020

The performance of heat exchangers still in good condition, except for Stabilizer Reboiler 235-E-201, because the dirty factor more than design specification.

12. Energy Losses, Potential Saving and Emission Reduction Potential

Based on heat balance calculation, energy losses from high temperature flue gas at Suban is coming from Stack of Thermal Oxidizer, GTG and GTC.

STACK LOSS, Btu/hr

TEMP, Deg F

Thermal Oxidizer

225-H-102 35,495,414 932

225-H-202 8,303,983 2,012

GTG

247-GT-201A 33,163,974 916

247-GT-201B 29,310,275 921

247-GT-201C 29,397,944 925

GTC

242-K-101 21,555,786 1,213

242-K-301 22,755,271 1,261

242-K-401 21,806,787 1,237

TOTAL 201,789,433 1,177

a. Energy Losses :

Total losses from flue gas is around 201 MMBtu/hr with average temperature 1,177 deg F. Actually, by utilizing economizer with stack temperature around 500 deg F, this Flue gas losses can be used to generate saturated steam about 120,000 lb/hr.


b. Potential Saving :

Based on the evaluation, shows that the potential saving are coming from :

Optimize operation of GTG will increase efficiency from 18 % to 23 % that will reduced HP Fuel consumption about 0.14 MMSCFD

Optimize operation of all heater will increase efficiency around 5 %, that will reduced LP fuel consumption about 0.1 MMSCFD

Utilized flare gas that will reduced fuel consumption about 0.8 MMSCFD

Energy Conservation Opportunities :

Optimize operation of GTGs can be implemented by load shading

Optimize operation of Heater and utilized flare gas can be implemented by installing booster compressor to compress gas up to 180 psig. This fuel gas can be used for Gas turbine and in turn it will reduce HP Fuel consumption. The simple calculation are as follows :

Fired Heater-saving, MMSCFD 0.10

, US $/Year 123,750.00

Flare Gas-saving, MMSCFD 0.80

, US $/Year 990,000.00

Total, MMSCFD 0.90

, US $/Year 1,113,750.00

*Cost to install the system for recovery gas which includes : gas compressor, KO Drum, Instrumentations , US $

2,400,000.00

Operation and Maintenance Cost , US $/year 120,000.00

Net income , US $/Year 993,750.00

Estimated payback period to install the system , Years

2.42

* = refer to Beak Pacifik Report - Energy Audit at Cilacap Refinery Complex

(Beak Pacific Inc. , Vancouver, Canada)

c. Emission Reduction Potentials

CO2 emission at suban gas plant is 127,901 lb/hr. its come from combustion of fuel gas at flare gas, heater, GTC and GTG.


CO2 reduction, lb/hr

Optimized operation of GTG 642

Optimized operation of Heater 824

utilized flare gas 7,394

Total 8860

Optimised operation and utilized flare gas will reduce CO2 emission , %

7%

13. Reporting system

Findings :

Existing daily report just only for production activity, it does not cover the data for plant performance evaluation purposes

No data acquisition and evaluation based on daily log sheet .

Important data for plant performance not covered in daily log sheet

Recommendation :

Daily reporting must covers production activity and plant performance indicator

Regulars summary of log sheet regarding plant performance should be evaluate.


IV. ENERGY ASSESSMENT AT GRISSIK CENTRAL GAS PLANT


4.1.1. GENERAL PLANT OPERATION OF GRISSIK GAS PLANT

The Central Gas Processing – Grissik plant was designed firstly for processing gas from four field in the Corridor Block, South Sumatra: Dayung/Sumpal and GLT (Gelam/Letang/Tengah) field. The quality gas from Dayung field has high CO2

content (31 %) and the gas quality from GLT has high condensate content.

The source of inlet gas to be processed in CGP has changed after the Suban Gas Plant was operated. Partly of Suban Gas sales line also was processed in CGP if the specification of Suban Gas Sales was nearly out of specification, especially on the CO2 content. So, the mixed gas from Suban plant and CGP plant will meet specification at the gas sales pipeline.

The simple process flow of CGP-Grissik Plant is shown with block diagram in figure 1.1 below:

T

Dayung Gas Gathering Station

T

Gelam Gas/Liq Gathering Station

T

Suban Gas Sales to processed in CGP

T

Gas/Liquid Separation

1 T

Gas Pretreatment

2A T

Amine System

4 7 T

GasDehydration System

9

65

T3

8

10

11

Condensate Stabilization & C3 Recovery

Gas Sales to pipeline

Condensateproduct to Bentayan

Acid GasPermeate Gas

Flare Gas

Gelam Gas

Gelam Liquid

2B

T

Suban Gas Sales bypass

T PropaneChil ler

Figure 4.1 Gas Processed Block Diagram of CGP plant

The flow diagram of CGP Grissik plant that obtained from basic design and field survey can be described below:


Table 4.1. Flow Diagram (based on Design)

2ADy&Sum

GasGlm Gas

Dy&Sum Gas

Dy&Sum Gas #1

Glm GasDy&Sum Gas #2

Dyg/Sum Gas

Glm Gas Glm Gas

Temp (deg F) 87 87 120 99 84 99 120 120 130

Pressure (psig) 1000 1000 1121 1099 1133 1099 1093 1125 1119Flow, Gas (MMSCFD) 310 129.46 302.2 114.02 129.46 114.02 197.56 114.38 114.1

Flow, Cond. (BBL/D) 0 0 0 0 0 0 0 0 0TOT_FLOW (MMSCFD) OR BBL/D 302.2

Glm Liq. to Stabilizer

Glm GasDy&Sum

GasAcid Gas

Glm Condensate

Codensate prod.

Flare GasDyg/Smp

Gas

Unit

Stream1 3 2B 4 5 6 7 8

176 1133 9 11 1094 1087 575 75

53 84 99 120 50

439.46 520.2 129.46 357.5 70.22 46.5

0.16

520.2 0 0 0 777.83 1745 0

197.06

0

0 129.46 70.22 46.5 0 0

311.16311.94 777.83 1745 0.16

9

132 100 58

10 11

Table 4.2. Flow Diagram (Survey on Oct. 02, 2007)

2ADy&Sum

GasGlm Gas

Dy&Sum Gas

Dy&Sum Gas

Glm Gas Sub GasDSS*) Gas

Glm GasBypass

SubDSS Gas Glm Gas

Temp (deg F) 87 87 138 123 84 87 120 120 94.5

Pressure (psig) 1105 1011 1001 1023 1001 1000 993 1000 998Flow, Gas (MMSCFD) 53.2 47.1 53.2 46.7 47.1 101.6 132.85 41.95 434.68 146.46 39.39

Flow, Cond. (BBL/D) 0 0 0 0 0 0 0 0 0 0 0

TOT_FLOW (MMSCFD)

OR BBL/D for Liquid 100.3

11

*) DSS : Dayung/Sumpal & Suban

0

Flare GasCod. prod.

0

5.75

5.75

205

80

9

620.53

Acid Gas

143.15

12.1

20.6

0

37

1000

0

109

23

2.57

174.8 829.95 1324

2B

Glm Gas

84

1001

47.1

0

Glm Cond.

93.1 90

10Stream

1 5 6 7 83

20.647.1

1296829.95866.77

993 203142

0

866.77

Unit 4

195.4

Dy&Sum Gas

100.3035 2.57

84

Glm Liq. to Stablzr

0

Based on overall process, the processing load of CGP plant during field survey activity is 54.6% of capacity design. This condition is caused by shut down condition for repairing of the Amine Regenerator 25-C-202.

4.1.2. GENERAL PLANT PERFORMANCE OF GRISSIK CENTRAL GAS PLANT

The HP fuel gas supply for the plant is obtained from the Back-up sales gas line and Suban taping gas line via the pressure control valve. Gas heated by steam, under back pressure control, goes to the high pressure fuel gas scrubber which is operated at about 260 psig. The high pressure fuel gas supplies fuel the gas turbine and partly sent to Bentayan field.

The LP fuel gas from the stabilizer feed drum and stabilizer overhead is supplied for TEG regeneration heater, gas pretreatment heater, fuel gas for WHB incenerator and flare purge gas, flare stack pilot, tank blanket.

The HP fuel gas is supplied to GTG and to the LP fuel gas, when the LP gas demand exceeds the available LP fuel gas supply.

CGP Grissik plant used three (3) type of energy for the process, utility and offsites facilities. The types of energy that used are : LP Fuel gas, steam from WHB and electricity from GTG.

Based on 2 October 2007, the amount of fuel gas coming from scrubber is 5.910 MMSCFD. The distribution of fuel gas as shown in table below;


Table 4.3 : Fuel gas distribution

1 Fuel Gas to Flare

C 1.460

2 Fuel Gas to WHB

46-B-101 D 1.550

46-B-201 D -

D 1.550

3 Fuel gas to Heater

41-H-101 C 0.023

41-H-201 C 0.023

41-H-301 C -

C 0.045

4 Fuel gas to Regen Heater

21-H-101 C 0.161

21-H-201 C -

0.161

5 Fuel gas to GTG

47-GTG-101A C 0.70

47-GTG-101B C 0.78

47-GTG-101C C -

D 1.48

6 Fuel gas to Bentayan

D 1.560

There are two type of fuel gas used, LP Fuel gas which is consumed by fired heater and HP Fuel gas which is consumed by GTG. The heating value of LP Fuel gas is around 1,060 Btu/SCF and HP Fuel is around 1,484 Btu/SCF

Based on heat balance calculation in WHB and GTG, the energy picture based on 2 October 2007 which includes total energy input/heat released, heat absorbed, heat loss and CO2 emission as shown in table below,


Table 4-4 : The energy picture based on 2 October 2007

HEAT RELEASE, Btu/hr

HEAT ABSORB, Btu/hr

STACK LOSS, Btu/hr

TEMP, Deg F

CO2 Emission,

lb/hr

FLARE

90,840,020 0 84,736,763 1,562 12,421

HEATER

Regen Gas Heater

21-H-101 8,473,864 5,794,116 2,487,229 430 1,377

21-H-201 0 0 0 0 0

Glycol Heater

41-H-101 1,196,695 922,279 256,466 430 191

41-H-201 1,196,695 922,279 256,466 430 191

41-H-301 0 0 0 0 0

W H B

46-B-101 165,049,729 120,492,608 41,432,959 376 158,802

46-B-201 0 0 0 0 0

GTG

47-GTG-101A 37,103,706 7,084,939 19,478,242 949 4,569

47-GTG-101B 40,880,730 7,415,749 18,133,682 967 5,034

47-GTG-101C 0 0 0 0 0

TOTAL 344,741,441 142,631,970 166,781,807 468 182,585

Plant Performance :

The plant performance at 2 October 2007 are as follows :

Table 4-5 : Plant Performance of Grissik Central Gas Plant

PRODUCTION RATESales Gas = 186.50 MMSCFD

= 31,083.33 BOE

Condensate = 1,234.00 BOE

Total Prod => 32,317.33 BOE

ENERGY CONSUMEExcluding Flare 256,621,725.71 Btu/hrIncluding Flare 347,461,746.16 Btu/hr


ENERGY INTENSITYExcluding Flare 7,940.68 Btu/BOEIncluding Flare 10,751.56 Btu/BOE

Total heat input to WHB, GTG,Regeneration Gas Heater and Glycol Heater is 253,901,420 Btu/hr and total heat released including flare gas is 344,741,441 Btu/hr. The production rate is 32,317.33 BOE which include 186.5 MMSCFD sales gas and 1,234 Barrel of condensate, means the energy consumed to produce one BOE (energy intensity) is 7,940.68 BTU/BOE (Excluding flare) and 10,751.56 BTU/BOE Including flare).


4.2.1. GAS PRETREATMENT & MEMBRANE SYSTEM

A. DESCRIPTION

The Gas Pre-Treatment Unit has been designed to operate at 2 x 50% each train with a total gas throughput capacity of 230 MMSCFD and designed to remove heavy hydrocarbons (C6+) from 380 ppm to 39 ppm.

The overall process works on the principles of Adsorption, Regeneration and, Cooling and, is commonly referred to a Thermal Swing Adsorption (TSA) process. Each train has 4 Adsorber Towers. Under normal operation each train has 2 Adsorber towers in operation mode,one Adsorber Towers in Regeneration mode and one Adsorber Towers in cooling mode.

The pretreatment consists of the following four steps process, i.e :

Coalescing filter for the removal of aerosols and particulates;

Heater to ensure the gas is above the dewpoint temperature;

Guard bed for the removal of heavy hydrocarbons and glycol;

Polishing filter

The Dayung gas from inlet separator is sent to the membrane unit to remove CO2, lowering the CO2 content of the gas from about 30.5 mole% to less than 15.0%.

The Membrane CO2 separation unit was designed to process the Dayung gas to reduce the CO2 content of the gas from 31% to 15%. The remainder of the CO2 in the Dayung gas is then removed in the Amine-treating Unit, allowing the gas to meet the sales gas pipeline specification for CO2, which has a minimum value of 5%. As the Dayung gas flows through the semipermeable polimide membranes, approximately 63% of the CO2, 60% of the H2S, and 8% of the Methane is separated into the permeate gas stream. The permeate Gas, consisting of about 80% CO2 and 20% Methane, is sent to the Waste Heat Boilers as fuel gas.


B. PERFORMANCE

The main equipment at Gas Pretreatment (TSA) system are Regenerator Gas Heater and Regen Gas/Gas Exchanger

The performance of main equipment are as follows :

Table 4-6 : Performance of Performance of Regenerator Gas Heater :

2-Oct-07 DESIGN

21-H-101 21-H-201 21-H-101/201

1 FUEL,

Flow, MMSCFD 0.16 OFF 0.31

2 FLUE GAS

T out, F 430.00(Estimated)

OFF 430.40

O2, % 14.00(Estimated)

OFF 14.00

Excess Air, % 185.64 OFF 185.64

3 PERFORMANCE

Heat absorption (LHV), MMBtu/hr

5.75 OFF 11.06


5.80 OFF 11.16

Efficiency (LHV), % 74.65 OFF 74.62

Efficiency (HHV), % 68.40 OFF 68.38

4 CO2 EMISSION

CO2 Emission from fuel gas, lb/hr

1,376.93 OFF 2,651.23

Regen gas heater is operated at 60% load compare to design condition and the fuel consump is 0.16 MMSCFD

The stack temperature and oxygen content are estimated close to design condition with the efficiency is 74.65 %


Table 4-7 : Performance of Regen Gas/Gas Exchanger (21-E-101/201)

21-E-101 21-E-201 DESIGN

Gas to Membrane (Shell side)

Pressure, psig 1097 OFF 1153



Flowrate of Gas, MMSCFD 26.00 OFF 215.07

Hot Gas (Regen Gas)



Delta T LMTD 62.74 OFF 61.89

HEAT DUTY, Btu/hr 475,664 OFF 7,497,708

HEAT TRANSFER RATE, BTU/(Hr/Ft2.F) 3.12 OFF 6.26

Table 4-8 : Performance of Cooler Gas/Gas Exchanger (21-E-102/202)

21-E-102 21-E-202 DESIGN

Regen Heater Gas/Hot Gas (Shell side)

Pressure, psig 1097 OFF 1155



Flowrate of Gas, MMSCFD 20.00 OFF 25.93

Cold Gas (Regen Gas)



Delta T, LMTD 194.18 OFF 212.40

HEAT DUTY, Btu/hr 4,674,675 OFF 8,267,466.11


HEAT TRANSFER RATE, BTU/(Hr/Ft2.F) 44.17 OFF 55.43

The above table shows that the heat duty operated only about 0.475 MMBTU/hr for E-101 and 4.67 MMBTU/hr for E-102, although the design heat duty is 7.5 MMBTU/hr for E-101 and 8.26 MMBTU/hr for E-102. This heat duty value produce capacity only about 6.34 % for E-101 and 56.54 % for E-102 compare to design capacity.

This condition caused by the feed gas to TSA unit only 26 MMSCFD (110,283 lb/hr) for adsorption and 20 MMCSFD (87,483 lb/hr) for cooling condition compare to the design capacity for gas process adsorption is 115 MMSCFD (20% capacity).

The different between design and operation are the LMTD value. Actual LMTD is 62.74 oF for E-101 and 44.17 oF for E-102 compare to design is 61.9 F for E-101 and 55.43 oF for E-102.

The performance of heat exchanger can be evaluated from the value of overall heat transfer rate (U). The U at operating condition give value about 3.12 BTU/(Hr/Ft2.F) for 21-E-101 and 44.17 BTU/(Hr/Ft2.F for 21-E-102, while the design value is 6.26 BTU/(Hr/Ft2.F) for 21-E-101 and 55.43 BTU/(Hr/Ft2.F) for 21-E-102.

4.2.2. AMINE SYSTEM

A. DESCRIPTION

The gas treating process consists of three identical amine contactors, two normally treating about 114 MMSCFD of Dayung gas each (referred design base) and the third treating about 129 MMSCFD of Gelam, Letang, Tengah (GLT) gas. The amine units are designed to produce treated gas containing less than 2% CO2 and 4 ppmV H2S consequently the bypasses allow the sales gas still to meet its specification of 5% CO2 and 8 ppmV of H2S.

Amine unit feed gas stream enters the bottom of an amine contactor where it is counter-currently contacted with lean 50 wt% UCARSOL solution with main composition is MDEA solution. CO2 and H2S are absorbed by the lean amine and the treated gas exits the top of the tower. The amine contactor contains stainless steel structured packing.

The design lean amine circulation rate to the Dayung gas contactors is about 1640 US gpm and the design lean amine circulation rate to GLT gas is about 1621 USgpm based on maximum allowable rich amine loading of 0.49 mole (CO2+H2S)/mole UCARSOL (MDEA solution).

The rich amine from the contactors flows under level control to the rich amine flash drums. Gas from the flash drums flows under back pressure control to the waste gas incenerators. The rich amine flows under level/flow control through the lean/rich amine exchangers where it is heated to about 206 oF by heat exchange with the hot lean amine from the two regenerators.


The rich amine feeds the regenerator above the stripping section which contains stainless steel structured packing. CO2 and H2S are stripped from the rich solution by steam produced in the regenerator reboilers which consist of 4 (four) kettle type shell and tube heat exchanger for each regenerator.

B. PERFORMANCE

The main equipment of amine system are Regenerator Reflux Condenser 25-E-101/202, Amine Reg. Reboiler 25-E-102A-D /202A-D , Lean amine cooler 25-E-103/203, Rich / Lean Amine Exchanger 25-E-104A/B, 25-E-204A/B; Amine Charge Pump 25-P-102A/B/C; Amine Booster Pump 25-P-101B/C

Table 4-9 : Performance of Amine Regenerator Re-boiler:

25-E-102A-D 25-E-202A-D DESIGN

STEAM SIDE (SHELL):

Pressure, psig 63.00 OFF 50.00

Temp sat'd steam, F 300.00 OFF 297.00

Flowrate Steam (25-FIC-121), Lb/hr 101,954.00 OFF 101,564.00

Flowrate Steam (25-FIC-122), Lb/hr 102,586.00 OFF 101,564.00

AMINE SIDE (TUBE):

Temp amine to Regenerator, F 259.50 OFF 261.00

Flow of Rich Amine to be regenerated, Lb/hr

1,309,729 OFF 1,299,665

Delta T 44.25 OFF 39.25



132 OFF 173

The above table shows that the actual heat duty is closed to the design. The difference between actual heat duty and design value only 5%, although the flow rate regenerated rich amine higher than design, the temperature outlet of amine reboiler less than design (actual is 249.5 deg F and design value is 262 deg F).

The overall heat transfer rate (U) at actual condition is 132 BTU/(Hr/Ft2.F) compare the design is 173 BTU/(Hr/Ft2.F. This condition caused by the LMTD of actual is higher than design value.


Table 4-10 : Performance of Lean Amine Cooler :

25-E-103 25-E-203 DESIGN

LEAN AMINE side:

Pressure, psig 110.00 110.00 180.00

Temp inlet, F 190 190 224

Temp outlet, F 106 104 120

Flowrate of Lean Amine, Lb/hr 799,305 670,882 1,375,016

AIR COOLANT side:

Temp inlet, F 92 92 95

Temp outlet, F 129 129 141.3

Delta T LMTD 31.93 30.14 48.20

HEAT DUTY, Btu/hr 62,223,295 53,469,455 123,624,938



CALCULATE FAN OPERATED 6 5 12


2 2 3

The above table shows that the heat duty actual of 25-E-103 and 25-E-203 are operated at 50% to the design. This caused by the flow rate of lean amine to be cooled also only about 50% - 60% from design capacity.

The flow rate of lean amine does not affect to the power required of fan cooler driver, so the power required to motors also higher than calculated value. At this case, the actual fan be operated closed to design (11 fans for 25-E-103 and 12 fans running for 25-E-203). This condition related with performance of cooler, especially with heat transfer rate. The U (overall heat transfer rate) at operating condition give value about 2 BTU/(Hr/Ft2.F) for operated and 3 BTU/(Hr/Ft2.F for the design value. This difference indicated that the performance of cooler lower than the design performance.

Table 4-11 : Performance of Rich-Lean Amine Exchanger:

25-E-104A/B 25-E-204A/B DESIGNRICH AMINE SIDE

Pressure, psig 108.00 OFF 95.00Temp inlet, F 155.00 OFF 167.00



Flowrate of Rich Amine, USGPM 2,572.00 OFF 2,496.80 LEAN AMINE SIDE

Temp inlet, F 250.00 OFF 261.00 Temp outlet, F 229.00 OFF 224.00 Delta T LMTD 59.48 OFF 55.99

HEAT DUTY, Btu/hr 53,656,356 OFF 42,413,111 HEAT TRANSFER RATE, BTU/(Hr/Ft2.F) N/A OFF N/A

The above table shows that the heat duty operated of exchanger 25-E-104A/B is higher than design value. The difference is about 25% higher than design.

The different heat load should be caused by :

Design amine is CR302, but the actual operation is AP-16668. The difference of amine causes different specific heat.

Flow rate of rich amine at operation is higher than the design value (3.5% difference)

The difference between operated LMTD and design is 6.5%.

Table 4-12 : Performance of Regenerator Reflux Condenser :

25-E-101 25-E-201 DESIGN

ACID GAS SIDE :Temp inlet, F 218.47 OFF 217.00

Temp outlet, F 143.15 OFF 120.00Flow of acid gas removed, MMSCFD 20.60 OFF 23.25

AIR COOLANT SIDE :Temp inlet, F 92.00 OFF 95.00

Temp outlet, F 132.00 OFF 131.60Delta T LMTD 67.27 OFF 57.60


ELECTRIC CONSUMPTION, KW 23.79 OFF 29.84ACTUAL FAN OPERATED 11.00 OFF 12.00

CALCULATE FAN OPERATED 10.83 OFF 12.00HEAT TRANSFER RATE,

BTU/(HR.Ft2.degF)3.57 OFF 4.19

The above table shows that regen reflux condenser and amine regenerator re-boiler are operated close to design condition. It has difference of heat duty about 11% than the design value. This caused by the flow rate of acid gas to be removed also only


13% less than the design capacity (operated is 20.6 MMSCFD, and the design value is 23.25 MMSCFD).

Power required of motor fan driver also proportional with the exchanger heat duty. At this condition the actual operate 11 fans, and the calculated result is also same fans to be operated.

Caused by the flow rate capacity of cooler load, the overall heat transfer also follow with this condition. The U (overall heat transfer rate) at operating condition give value about 3.57 BTU/(Hr/Ft2.F) and 4.19 BTU/(Hr/Ft2.F for the design value.

Table 4-13 : Performance of Amine Charge Pump

DESCRIPTION UNIT 25-P-102C Design

value value

specific gravity 1.03 1.00

Temperature F 245.00 70.00

suction pressure psia 98.00 25.00

discharge pressure psia 1210.00 1185.00

flow GPM 2862.00 2487.00

Total head ft 2,503.97 2679.60

Electric motor power HP 2240.00 2059.00

Mechanical work HP 1946.39 1719.89

Efficiency % 86.89 83.53

Only one Amine charge pump (Charge pump C) was running very close to design condition. It’s efficiency reached 86.89% with flow rate of 2862 GPM, This pump is designed to running with 83.53% efficiency at 2487 GPM flow rate. The pump was running actually in even higher efficiency than the design condition. Attention should be addressed to this situation since the pump draw consumed electric power of 2240 HP. It just below it's maximum power rating: 2250 HP.

Table 4-14 : Performance of Amine Booster Pump

DESCRIPTION UNIT 25-P-101B 25-P-101C Design

value value value


Temperature F 180.00 180.00 70.00

suction pressure psia 16.70 18.70 N/A

discharge pressure psia 119.70 129.70 N/A

flow GPM 1556.00 1306.00 2871.00


Total head ft 231.93 249.95 188.00



Efficiency % 69.03 65.19 81.94

Two of the Amine booster pumps were running. They were Amine Booster pump B and C. Their efficiencies are 69.03% at 1556 GPM and 65.19% at 1306 GPM respectively. At the other side, we have data from design condition when each pump handles 2871 GPM. At this design condition, we got 81.94% efficiency. These two pumps were running in good condition and within the range of operation.

4.2.3. REFRIGERATION SYSTEM

A. DESCRIPTION

Propane refrigerant gas from gas chiller at 75 psig, compress by propane compressor (single stage screw compressor). The compressor discharge at about 252 psig goes to the propane condenser where it is totally condensed at about 122 oF. The propane condenser is an air cooled heat exchanger.

The condensed propane goes to the propane accumulator and then to the gas chiller via the level control valve. The refrigerant chills the sales gas from 57 F to 45 F and then goes to LTS to separate the gas from the condensate.

B. PERFORMANCE

The main equipment at Refrigeration System are Exchanger (Gas chiller 30-E-102), Propane compressor 30-K-101A/B and Gas/Gas Exchanger.

Table 4-15 : Performance of Gas Chiller

UNITS DESIGN EVAPORATOR

TEMPERATURE GAS IN DEG.F 57.00 57.00

TEMPERATUR GAS OUT DEG.F 45.00 45.00

GAS FLOW MMCFD 100.00 39.00

CONDENSATE FLOW BCD 700.00 700.00

HEAT RELEASE BTU/H 2,477,633.80 841,348.85

ACTUAL POWER KW 260.00 110.00

C.O.P 2.79 2.24


The above table shows that the refrigeration system operated at low load and the propane chiller are operated at 40 % load (39 MMSCFD ) at actual power 110 KW compare to design condition. The COP at actual condition is 2.24 compare to design value is 2.79

Table 4-16 : Performance of propane compressor

Only one compressor is operated to handle the refrigeration system. The operating conditions are as follows;

UNITS DESIGN ACTUAL

SUCTION TEMPERATUR ( oF ) 35.00 30.00

CONDENSING TEMPERATUR ( oF ) 127.00 120.00

PROPANE FLOW LBS/H 14,000.00 7,191.72 (Calculated)

TOTAL POWER REQUIRED KW 242.17 101.64

ACTUAL POWER KW 260.00 110.00

COP 3.00 2.87

At the actual condition, the refrigerant flow is 7191 lb/hr at actual power 110 KW and COP = 2.87. Compare to design condition, the refrigerant flow is 14,000 lb/hr at power design 260 KW and COP = 3. It means that the performance of compressor is still in good condition.

Table 4-17 : Performance of Gas/Gas Exchanger

30-E-101 DESIGN

HOT GAS (FR GELAM CONTACTOR):


Temp inlet, F 130.00 129.60

Temp outlet, F 60.00 64.40

Flow rate of Gas, MMSCFD 39.39 114.00

GELAM SALES GAS side:

Temp inlet, F 40.00 50.00

Temp outlet, F 120.00 117.00


Delta T LMTD 14.43 13.48

HEAT DUTY, Btu/hr 3,159,954 10,705,230.41

HEAT TRANSFER RATE, BTU/(Hr/Ft2.F) 0.23 0.30

The above table shows that gas/gas exchanger at the dew point control system have heat duty only 30% refer to the design value. This caused by the flow rate of gas also only 35%. The temperature profile of gas also not have high different between operated and design value.

Caused by the flow rate capacity of gas to the gas/gas exchanger, the overall heat transfer also follow with this condition. The U (overall heat transfer rate) at operating condition give value about 0.23 BTU/(Hr/Ft2.F) and 0.30 BTU/(Hr/Ft2.F for the design value.


A. DESCRIPTION

The hydrocarbon liquid from the feed drum is fed under level control to the top tray of the condensate stabilizer. The stabilizer is a 32 inch ID reboiled stripping column containing 18 stainless steel valve trays.

The stabiliser reboiler is a kettle type shell and tube exchanger utilizing about 3404 lb/h of 140# steam at normal operation. During normal operation about 1738 bbl/day of 10 psi RVP condensate are produced. The condensate product from the stabilizer is sent via the HC condensate cooler bundle in the refrigerant condenser air cooled exchanger frame.

B. PERFORMANCE

The main equipment at Condensate Stabilizing system are Stabilizer Re-boiler 35-E-102, and Condensate cooler 35-E-101

Table 4-18 : Performance of Stabilizer Reboiler 35-E-102 :

35-E-102 DESIGN

STEAM SIDE (SHELL)

Pressure, psig 117.00 150.00

Temp sat'd steam, F 330.00 330.00

Flow rate (35-FIC-006), Lb/hr 803.00 3,751.35

CONDENSATE SIDE (TUBE)

Temp Condensate to re-boiler, F 278.00 261

Delta T 66.00 69.40


HEAT DUTY, Btu/hr 700,201 3,470,000

HEAT TRANSFER RATE, (BTU/Hr.Ft2.F) 6.52 30.73

The above table shows that actual heat duty of 35-E-102 is only 20 % compare to design condition because the flow rate of feed liquid to the stabilizer is only 20 % - 25% compare to design.

Due to the flow rate of stabilizer re-boiler is only 20% than the design, the U (overall heat transfer rate) at operating condition give value about 6.52 BTU/(Hr/Ft2.F) compare with the design value, 30.73 BTU/(Hr/Ft2.F

Table 4-19 : Performance of Propane Condenser and Condensate Cooler

30-E-105 DESIGN 35-E-101 DESIGN

FLUID SERVICES: PROPANE COONDENSOR

CONDENSATE


Temp inlet, F 140.00 158.00 316 316.00

Temp outlet, F 119.00 124.00 120 120.00

Flow rate, MMSCFD (gas) 4.50 5.13

Flow rate, BBL/day (liquid) 1324 2,174

AIR COOLANT SIDE :

Temp inlet, F 92.00 95.00 92 95.00

Temp outlet, F 105.00 109.90 105 109.90

Delta T LMTD 30.83 35.30 53.68 85.85

HEAT DUTY, Btu/hr 3,086,550 3,796,245 718,616 1,995,227

ELECTRIC CONSUMPTION, KW 14.72 22.38 14.72 22.38

The arrangement of cooler in this area is designed to serve three stream cooling fluid, i.e : Propane condenser, Propane overhead condenser and condensate stabilizer. Only one fans cooler installed to cool them. At the plant survey, the propane overhead condenser was off.

Heat Load total at actual condition of two condenser (30-E-105 and 35-E-101) are 3.8 MMBTU/hr compare with the design value is 5.7 MMBTU/hr. This heat load gives


percentage about 65 % of heat load capacity similar with electrical consumption is 65 % too.

4.2.5. DEHYDRATION SYSTEM

A. DESCRIPTION

The water saturated gas from the three amine trains is dehydrated by contacting it with lean triethylene glycol (TEG) in the three, identical glycol contactors. The design water content of the dry gas is 10 lb H2O per MMSCFD. The dehydrated GLT gas is recombined with the GLT amine unit bypass gas, sent through the dewpoint unit and then to sales. The Dayung/Suban gases from two of the glycol contactors and the Dayung/Suban amine unit bypass gas are sent directly to Sales.

Lean glycol is fed to the top of the glycol contactor at a rate of about 30-USgpm. A coil is provided in the top of the tower to cool the glycol from about 210 oF to less than 150 oF by heat exchange with the dried gas leaving the contactor. The glycol flows downwards through the structured packing in the column counter-currently contacting and absorbing water from the gas flowing upwards through the packing.

The rich glycol accumulates on the chimney tray and is sent under level control to the glycol regeneration skid. The dry gas exits the top of the contactor with the Dayung/Suban gasses going to sales and the GLT gas going to the hydrocarbon dew-point control unit.

The three glycol regeneration skids are identical. There are no connections between the glycol regeneration skids or between the glycol lines in each train.

B. PERFORMANCE

Table 4-20 : Performance of Rich – Lean Glycol Exchanger

41-E-101 41-E-201 41-E-301 DESIGN

LEAN TEG SIDE

Pressure, psig 10.50 11.50 11.00 50.00

Temp inlet, F 380.00 370.00 360.00 360.00

Temp outlet, F 150.00 165.00 160.00 225.00

Flow rate of Lean TEG, USGPM 20.18 24.00 24.00 30.48

RICH TEG SIDE

Temp inlet, F 140.00 142.00 140.00 171.00

Temp outlet, F 200.00 200.00 196.00 306.20

Delta T LMTD 58.82 61.13 66.25 51.90

HEAT DUTY, Btu/hr 1,400,267 1,477,137 1,439,554 1,485,141


HEAT TRANSFER RATE, BTU/(Hr/Ft2.F)

104.88 88.55 92.66 128.20

The above table shows that Rich/Lean Glycol Exchanger are operated close to design condition. Its heat duty is only 5% differ than the design value, although the flow rate of glycol at the operation only 70% - 80% than design capacity. This condition is caused by the difference of LMTD between operated and design value. The operating condition gives temperature outlet of Lean glycol lower than design value.

Due to the flow rate capacity of cooler load, the U (overall heat transfer rate) at operating condition give value about 70%-80% than the design value.

Table 4-21 : Performance of Glycol Heater

2-Oct-07

41-H-101 41-H-201

1 FUEL,

Flow, MMSCFD 0.02 0.02

2 FLUE GAS

T out, F 430.00 430.00

O2, % 7.00 7.00

Excess Air, % 45.77 45.77

3 PERFORMANCE


Heat absorption (HHV), MMBtu/hr 0.92 0.92

Efficiency (LHV), % 84.91 84.91

Efficiency (HHV), % 77.08 77.08

4 CO2 EMISSION

CO2 Emission from fuel gas, lb/hr 191.42 191.42

The heat duty of Glycol heater is 0.91 mmbtu/hr (calculated from process site). Assuming the oxygen content of flue gas is 7%, the calculated efficiency is 84.91%.


4.2.6. WASTE HEAT BOILER

A. DESCRIPTION

Permeate gas from membranes, rich amine flash drum gas, and acid gas from the amine reflux accumulators are combined and sent to the waste gas incenerator. In the incenerator, the waste gas is incenerated by burning fuel gas at a sufficient high temperature to ensure the complete destruction (oxidation) of the H2S and hydrocarbons. The minimum exit gas temperature at the top of the stack is 450 oF to ensure that the allowable ground level SO2 concentration is not exceeded.

150 psig saturated steam is produced by two heat recovey boilers with each capacity of 230,000 lb/h. Normally, two boilers are operated to supply necessary steam for all users in CGP.

B. PERFORMANCE

The main equipment of Waste Heat Boiler system are Waste Heat Boiler 46-B-101/201, and BFW pump 46-P-102A/B/C.

Table 4-22 : Performance of Waste Heat Boiler

2-Oct-07 DESIGN

46-B-101 46-B-101/102

1 INLET GAS,

Fuel Gas Flow, MMSCFD 1.55 1.77

Acid Gas Flow, MMSCFD 20.23 48.11

Permeat Gas Flow, MMSCFD 8.35 68.39

2 FLUE GAS

T out, F 376.00 416.00

O2, % 7.00 2.62

Excess Air, % 45.77 13.17

3 BFW

lb/hr 200,392.00 245,000.00

T in Economizer, F 200.00 251.00

T out Evaporator, F 347.00 375.00

P in Economizer, Psi 132.40 175.70

P out Evaporator, Psi 123.00 170.00


4 PERFORMANCE

Heat Release (LHV), MMBtu/hr 149.52 822.94

Heat Release (HHV), MMBtu/hr 164.41

Heat Loss (LHV), MMBtu/hr 29.91 380.55

Heat Loss (HHV), MMBtu/hr 43.92


Heat absorption (HHV), MMBtu/hr 120.49

Efficiency (LHV), % 79.99 no Dsg Eff

Efficiency (HHV), % 73.29 no Dsg Eff

5 CO2 EMISSION

CO2 Emission from fuel gas, lb/hr 29,070.86 no Dsg CO2

CO2 Emission from Acid gas, lb/hr 103,029.15 no Dsg CO2

CO2 Emission from Permeat gas, lb/hr 42,586.20 no Dsg CO2

Total CO2 Emission, lb/hr 174,686.21 no Dsg CO2

The above table shows that the WHB are operated at only 50 % load compare to design condition, and the calculated efficiency is 80%. The temperature in flue gas are lower than design condition and the excess air is higher than design.

Table 4-23 : Performance of BFW Pump

DESCRIPTION UNIT 46-P-102A 46-P-102C Design

value value value


Temperature F 245.00 245.00 70.00

suction pressure psia 21.10 21.10 8.00

discharge pressure psia 274.70 274.70 230.00

flow GPM 380.00 380.00 528.00

Total head ft 585.82 585.82 512.82



Efficiency % 60.48 60.48 63.53


Like Amine booster Pumps, the two BFW pumps were running within the specification, and the efficiency reached is accepted. This BFW pump is designed to run with 63.53% efficiency at 528 GPM flow rate. Actually, two pumps were running at same rate of flow (380 GPM) with 60.48% efficiency.


A. DESCRIPTION

Electrical power is generated and distributed to provide the prower requirements for the gas plant and offsites. Electrical power Generator driven by Gas turbine generator, which gas supplied from HP (high pressure) fuel gas system. Three gas turbine are provided with two generator running and one on the standby mode. The design capacity of generator is 4500 kW each unit. The actual capacity on the field survey only about 2100 kW each turbine generator (45% of design capacity) and running two of three generators.

Generator specification is power 4688, voltage 4160, freq 50 Hz, cos Q 0.85. The large motor (lean amine charge pump, WHB Blower, propane compressor) supply by 6600 volt and the other motors using 400 volts.

B. PERFROMANCE

Gas turbine generators at Utility system are 47-GTG-101A/B/C

Table – 4.24 : performance of GTG

2-Oct-07 DESIGN

47-GT-101A 47-GT-101B 47-GT-101A/B/C

TURBINE

Fuel gas :

flow, MMSCFD 0.89 0.92 1.31

Flue gas :

Temperature, F 0 0 900

O2, % 16 16 16

Excess Air, % 296 281 267

Turbine Eff, % 21 21 30

Btu/kwh 16,571 16,077 11,559

CO2 Emission

lb/hr 4,870 5,034 7,914

GENERATOR

Power Output, KW 2,158 2,265 4,688

PF 0.81 0.83 0.84


V 4160 4160 4160

Frequency, Hz 50 50 50

The above table shows that GTG operated at 50 % load compare to design condition.

The calculated efficiency is only 21 % compare to design which is 30 %. The decreasing of efficiency of GTG is caused by low load and will be impact the increasing of the heat loss,

The heat rate of 47-GT-101A is 16,571 Btu/kwh, greather than design 16000 Btu/kwh but 47-GT-101B 16,077 Btu/kwh close to design.

Table 4-25 : The design performance of GTG are as follows

POWER 4500 4000 3500 3000 2500 2000 1500 1000

BTU/KWH 11600 12000 12600 13000 14000 16000 18700 25000


A. OPERATION

Instrument and utility air are supplied by the two 340 scfm, screw type compressor connectod in a lead-lag configuration. The compressed air is filtered and then dried in heatless adsorption type dries which are on automatic regeneration cycles. The instrument air compressor packages are provided with local electronic control panels.

The instrument air receiver is normally operated between 110 and 120 psig. The utility air take-off is equipped with a shut off valves to prevent utility air usage from drawing down the instrument air pressure.

B. PERFORMANCE

There are three compressors Atlas Copco GA 75 , 51-A-101A /B/C with design capacity is 340 SCFM, the performance of each equipment are as follows,

Table 4-26 : Performance of air compressor :

UNITS DESIGN ACTUAL

SUCTION PRESS PSI 14.70 14.70

DISCHARD PRESS. PSI 182.00 132.30

COMPRESS AIR FLOW SCFM 340.00 257.45


25-P-102 A/B/CAmine Charge pump A/B/C

2250 HP x3

25-PM-101 A/B/CLean amine booster pump A/B/C

200 HP x3

25-EM-103 A-MLean Amine cooler fan A-M

37.3 KW x13

25-PM-104Amine Sump pump

15 HP

25-EM-201 A-MRegenerator reflux condenser fan A-M

29.8 KW x13

25-EM-101 A-MRegenerator reflux condenser fan A-M

29.8 KW x13


7.50 HP x2

25-AM-101/102Anti foam injection pump

2 HP x2

4.16 KV

480 V

25-EM-203 A-MLean Amine cooler fan A-M

37.3 KW x13

POWER KW 72.60 44.17


The above table shows that the compressor is operated at low load. The performance can not be evaluate accurately because no flow meter of air

4.2.9. ELECTRICAL MAP CENTRAL GRISSIK GAS PLANT

Electric map for Central Grissik Plant is like the one for Suban Gas plant. It is derived from single line diagram, and intend to get a closer and clear point of view to one that need brief description on power consumption at each process. It Emphasize the voltage, and power required for each equipment.

The power mentioned at each equipment is the power in normal design condition.

A. Amine System

25-PM-105Amine Transfer pump

9 HP


30-PM-102Depropaniser reflux pump

3.5 HP

30-PM-101Depropaniser feed pump

5 HP

30-E-104Depropaniser reboiler heater

69 KW

35-PM-102 A/BCondensate shipping pump A/B

75 HP x2

480 V

30-EM-105 A/BPropane condenser fan A/B

22.3 KW x2

30-K-101 A/BPropane Compressor A/B

350 HP x2

4.16 KV

30-PM-103Propane Transfer pump

3 HP

30-K-101A/B-KM1Propane Compr. A/B L.O. cooler fan

5 HP x2

30-K-101A/B-PM1Propane Compr. A L.O. pump motor

5 HP x2

480 V

41-PM-102/2020/302 A/BGlycol circulation pump

25 HP x6

480 V

46-K-101/201Inc. Blower train A/B

400 HP

4.16 KV

B. Propane Chiller System

C. Depropanizer and Condensate Stabilization System

D. Dehydration System

E. Incinerator/Heat recovery System

41-PM-101Glycol transfer pump

1.74 HP


46-PM-103 A/BCondensate pump A/B

25 HP x2

46-PM-102 A/B/CBFW pump A/B/C

150 HP

46-EM-101 A/BExcess steam condenser fan A/B

22.3 HP x2

480 V

51-AM-101 A/BInstr. Air compressor A/B

125 HP x2

48-PM-101 A/BFlare KO drum pump A/B

3 HP x2

480 V

51-AM-101 A/B -2Instr. Air compressor A/B cooler fan

4 HP x2

55-PM-201 A/BUtility water pump A/B

15 HP x2

480 V

53-PM-201 A/BSoftened water pump A/B

7.5 HP x2

54-PM-201 A/BPortable water pump A/B

7.5 HP x2

F. BFW steam and Condensate System

G. Flare and Air compressor System

H. Utility System

4.3. FINDINGS AND RECOMMENDATION

1. Instrumentation and Metering

Based on the site survey founded that many metering and instrument are not work properly. Findings and recommendations of metering and instrumentation at Grissik Central Gas Plant are as follows :

Equipments Findings Recommendations

1. WHB There are unbalance between BFW flow and steam flow that will impact the direct method efficiency calculation is not accurate.

Oxygen analyzer not work properly ( direct measurement = 7 % , on

Need to calibrate meter of steam and BFW

Need to install sampling point to measure Boiler water quality and control the blow down


line analyzer = 14 %)

No Sampling point for water quality at steam drum

2 Glycol & Regen Heater

No meter fuel gas at the heater

The position of flue gas sampling point is far from platform

need to install fuel gas meter

need to install sampling line of flue gas close to the platform

3 GTG There are no flow meter of fuel gas in each GTG.

Need to install flow meter of fuel gas

Need to install sampling line of flue gas for each GTG

4 Propane Comp

No continue record of electric consumption for motor compressor

Need to records continously

5 Electric Distribution

No continue recorded for electric distribution

Need to record electric distribution (4160 line) at daily records

2. Waste Heat Boiler

Calculation result of WHB :

EFFICIENCY HEAT ABSORB

CO2 EMISSION

% MMBtu/hr Lb/hr

W H B - INCENERATOR 46-B-101

DESIGN N/A 442.38 N/A

46-B-101 79.99 119.60 174,686.21

46-B-102 OFF OFF OFF

Finding :

WHB is operated at high excess air (77 %) compare to the design figure which is 27 % excess air. The efficiency is 80 %


WHB is operated at low load ( 50 % load)

Recommendation :

WHB should be operated close to the design excess air

3. Heater

Calculation result of heater :

EFFICIENCY HEAT ABSORB CO2 EMISSION% MMBtu/hr Lb/hr

GLYCOL HEATER : 41-H-101

DESIGN41-H-101 84.91 0.91 191.4241-H-201 84.91 0.91 191.42

REG GAS HEATER : 21-H-101/201 DESIGN 74.62 11.06 2,651.2321-H-101 74.65 5.75 1,376.9321-H-201 OFF OFF OFF

Finding :

The heater are operated at low load (50 % load)

4. GTG

Calculation result of GTG :

EFFICIENCY HEAT RATE BHP CO2 EMISSION % BTU/KWH KW Lb/hr

GAS TURBINE GENERATOR DESIGN 29.52 11,558.78 4,687.50 7,914.10 47-GT-101A 20.59 16,571.34 2,158.33 4,869.94 47-GT-101B 21.23 16,077.04 2,264.58 5,034.10 47-GT-101C OFF OFF OFF OFF

Findings :

GTG are operated at lower load is around 50 % compare to design, but the performance ( heat rate ) are still close to design at low load


5. Propane Comp

Calculation result of Propane Compressor :

POWER REQUIRED,

KW

ACTUAL POWER, KW

PROPANE FLOW

COP

DESIGN 242.17 260.00 14,000.00 3.00 30-K-101A 101.64 110.00 7,191.72 2.87

Findings :

Based on the actual data, the refrigeration load is only 50 % compare to design condition, but the COP is 2.87 compare to design COP is 3. It means that the compressor is still in good condition

6. Gas Chiller

Calculation result of gas chiller :

UNITS DESIGN GAS CHILLER

GAS INTAKE TEMP.AT EVAP. DEG F 58.00 57.00 GAS OUTPUT TEMP.AT EVAP. DEG F 45.00 45.00 SALES GAS FLOW MMCFD 100.00 39.00 CONDENSATE FLOW BBL/D 700.00 700.00

HEAT RELEASE MMBtu/hr 2,645,934.62 841,348.85 TOTAL POWER KW 260.00 110.00 C.O.P 2.98 2.24

(Calculated)

Findings :

the temperature indicator inlet and outlet are still in good conditions

COP at gas chiller is 2.24 compare to design 2.98


7. Air cooler

Calculation result of coolers are as below:

Findings :

Power rated required for drive motors of fan coolers are below 1% - 2% due to their heat duties, except for Lean Amine 25-E-203 and Condensate cooler (25-E-101). This case indicate that power consumption of these coolers more waste energy (less efficiency).

Recommendations :

Need to check the cooler system of Lean amine cooler, because at the plant survey, they have high power consumption although the capacity of heat load only a half than design.

Need to check again the properties of amine used in operation, because it can effect the calculation performance of cooler and exchanger system in amine system.

No. COOLER HEAT DUTY HEAT TRANSFER RATE

ELECTRIC/HEAT DUTY

(MMBTU/HR) (BTU/HR.FT2.oF) ( % )

1. Amine Regen Reflux Cooler25-E-101 55.70 3.57 1.60%25-E-201 OFF OFF OFF

2. Lean Amine Cooler25-E-103 62.22 2.06 1.85%25-E-203 53.47 1.88 2.34%

3. Stab. Condensate Cooler35-E-101 0.72 5.03 8.85%

4. Propane Condenser Compressor Cooler30-E-105 3.09 2.89 1.63%

5. Propane Ovhd Cooler30-E-103 OFF OFF OFF


8. Heat Exchanger

Calculation result of heat exchangers are as below:

No. HEAT EXCHANGER HEAT DUTY HEAT TRANSFER RATE

DIRTY FACTOR ELECTRIC/HEAT DUTY

(MMBTU/HR) (BTU/HR.FT2.oF) ACTUAL DESIGN ( % )

1. Gas-Gas HE in TSA unit

Regen HE:

21-E-101 0.97 6.90 0.063 0.002 -

21-E-201 OFF OFF OFF OFF OFF

Cooler HE:

21-E-102 4.67 4.46 0.005 0.002 -

21-E-202 OFF OFF OFF OFF OFF

2. Rich/Lean Amine Exchanger25-E-104A/B 53.58 N/A N/A N/A -25-E-204A/B OFF OFF OFF OFF OFF

3. Rich/Lean Glycol Exchanger41-E-101 1.40 104.88 0.002 0.001 -41-E-201 1.73 117.99 0.001 0.001 -41-E-301 1.67 111.25 0.001 0.001 -

4. Gas-Gas Dew Point Control HE30-E-101 3.16 0.29 0.09 0.10 -

5. Amine Regen Reboiler25-E-102 A-D 184.59 132.16 0.002 0.001 -25-E-202 A-D OFF OFF OFF OFF OFF

6. Stabilizer Reboiler 35-E-102

0.70 6.52 0.001 0.001 -

7. Depropanizer Reboiler 30-E-105

0.14 N/A N/A N/A 102.32%

Findings :

Entirely, the performance of heat exchangers in Grissik plant still in good condition, except for Gas/GAs Exchanger in TSA unit is needed to check again for the fouling condition, because it’s dirty factor have higher than their specification (design).


9. Gas Pretreatment & Membrane system

CALCULATION OF MEMBRANE SYSTEM

Membrane Separation Rate 0.321556 lbmole/ lbmoleDesign Value of Membrane Separation 0.511022 lbmole/ lbmole

HYDROCARBON SLIP Rate 0.030709 lbmole/ lbmoleDesign Value of Hydrocarbon Slip Rate 0.063241 lbmole/ lbmole

Findings :

The Thermal swing adsorber (TSA) system running on good condition, because the C6+ concentration at the feed gas to membrane is 29 ppm compare to the design is 39 ppm.

The membrane system separation only give separation rate is 32% compare to the design 50% of CO2 feed, so the CO2 content in gas to contactor still high than design value.

Recommendation :

Need to check again the membrane module system to upgrade the separation rate.

10. Amine System

Findings :

The absortion rate capacity of amine contactor is only 38% refer to the design capacity rate. This case caused by the flowrate of gas processing capacity of lean amine only 40% than design.

Recommendation :

Need to operate full gas processing capacity to increase absorption rate in amine contactor due to reduce the energy consumption in amine system

11. Energy Conservation

a. Energy Losses :

Based on heat balance calculation, energy losses from high temperature flue gas (more than500deg F) at Grissik is coming from Stack of GTG. Total losses is 57,821,543 Btu/hr.

STACK LOSS, Btu/hr

TEMP, Deg F


GTG

247-GT-201A 30,471,332 949

247-GT-201B 27,350,211 967

247-GT-201C 0 0

TOTAL 57,821,543 958

Actually, by utilizing economizer with stack temperature around 500 deg F, this Fluegas losses can be used to generate saturated steam about 28,000 lb/hr.


b. Potential Saving :

Based on the evaluation, shows that the potential saving are coming from :

Optimize operation of WHB by reducing excess air (7 % O2 to 3% O2) increase efficiency aroumd 4 %, that will reduced LP fuel consumption to 0.06 MMSCFD

Utilized flare gas that will reduced fuel consumption to 1.0 MMSCFD

Energy Conservation Opportunities :

Optimized operation of GTG can be implemented by load shading

Optimized operation of Heater and utilized flare gas can be implemented by installing booster compressor to compress gas up to 180 psig. This fuel can be used for Gas turbine and in turn it will reduce HP Fuel consumption. The simple calculation are as follows :

WHB-saving, MMSCFD 0.06

, US $/Year 76,725.00

Flare Gas-saving, MMSCFD 1.00

, US $/Year 1,237,500.00

Total, MMSCFD 1.06

, US $/Year 1,314,225.00

*Cost to install the system for recovery gas which includes : gas compressor, KO Drum, Instrumentations , US $

3,000,000.00

Operation and Maintenance Cost , US $/year 120,000.00

Net income , US $/Year 1,194,225.00

Estimated payback period to install the system , Years

2.51

* = refer to Beak Pacifik Report - Energy Audit at Cilacap Refinery Complex

(Beak Pacific Inc. , Vancouver, Canada)

c. Emission Reduction Potentials

CO2 emission at suban gas plant is 182,886 lb/hr. its come from combustion of fuel gas at flare gas, heater, WHB and GTG. Optimized operation and utilized flare gas can reduce CO2 emission around 5 %


CO2 reduction, lb/hr

utilized flare gas 8,507.79

Total 8,507.79

Utilized flare gas will reduce CO2 emission , %

5%

12. Reporting system

Findings :

Existing daily report just for production activity it does not cover data for plant performance evaluation purpose

No data acquisition and evaluation based on daily log sheet .

Important data for plant performance not cover in daily log sheet

Recommendation :

Daily reporting must cover production activity and plant performance indicator

Regular summary of log sheet regarding plant performance should be evaluate.


V. ENERGY ASSESSMENT AT RAWA OIL PLANT

5.1 GENERAL PLANT OPERATION AND PERFORMANCE

5.1.1. PLANT OPERATION

There are wells at ConocoPhillips South Sumatra area that contents oil in significant amount and high gas concentration. Rawa plant is designed to process this oil, and re inject the gases to the injection wells.

High-pressure oil & gas came firstly from wells entering the plant via manifold, before entering the production processes. The first process is High-pressure separator (HP separator). Oil, MP Gas and Water is separated in this process. MP gas (450 psig) leave the top separator and water leave the bottom of the separator and then store it in the production water tank before send to Central Ramba.

Oil & LP gas mixture goes to medium pressure (MP) separator. In MP Separator, Oil & HP gas is separated. Oil is stored to the crude oil tank before ship to Plaju. LP Gas (50 psig) compressed by LP Gas compressor (gas engine) to raise it the pressure until 450 psig.

MP gas from HP separator mix with MP Gas from LP Compressor and then the HP Compressor driven by gas turbine to rise the pressure until 1200 psig. Water content in HP Gas is reduced by glycol system before injected to the wells. The design of HP Compressor is 45 MMSCFD and about 1 MMSCFD of process gas used for fuel.

The simplified process flow diagram of Rawa field is shown at diagram in figure 1.1

1 2

3

Prod water tank

5

Oil wells

HP Compressor

Glycol System

4

LP Compressor

InjectionTo wells

4Oil

Send to Plaju and Bentayan

Gas ScrubberMP Separator

To Ramba

HP Separator

Figure 5.1. Rawa prod. Block diagram (simplified)

MP Gas


Data from production records taken from 1-10 Aug 2007 at table 1 shows that oil extracted from wells is about 300-320 barrels/day (0.001%) and water produced is 1500-1600 (0.003%). About 21 MMSCFD gas derived is re injected to injection wells while the other product, i.e. fuel gas, is sent to Ramba station.

Table -5.1 : Oil Production Data

5.1.2. GENERAL PERFORMANCE EVALUATION

The Energy Source of Rawa oil Plant is LPgas used for gas turbine compressor (LP and HP) and Glycol Regenerator which comes from LP Separator. LP Compressor driven by gas engine to increase the LP Gas pressure from 60 psi to 450 psi and HP Compressor driven by gas turbine to increase the MP gas from LP Compressor and HP Separator to 1200 psi.

Fuel flow meter only for total consumption. There is no flow meter for eachconsumers. The total consumption is 0.7 – 1.1 MMSCFD

Rawa oil processing plant doesn't have electric power generation systems inside the plant itself. Electric power derived from Ramba power plant via medium voltage lines, 11KV, 3, 50 Hz. Incoming power line then is stepped down by a transformer to 380V/220V, 3, and in turn, this voltage system is applied to all the electrical equipments and machines inside the plant. There is no KW Meter in main panel. The estimate load is about 150 KW.

For emergency purposes, there is a diesel fueled electric generator (380V, 3, 50 Hz) that has capacity of 505 KVA. This generator set needed extra maintenance due to this machine is of the old type, and have been used over a long period of time.

5.2 PERFORMANCE EVALUATION OF MAIN EQUIPMENT

The main equipment at rawa oil plant are . HP Compressor 5000-PK-100 , LP Compressor 5000-PK-101 and Glycol Reboiler 3600-HT-103

The performance of HP and LP Compressor are as follows :


HP Compressor 5000-PK-100

Table -5.2 : Performance of HP Compressor 5000-PK-100

UNITS ACTUAL DESIGN

INJECTION GAS MMCFD 39.20 45.00

ABSL.SUCTION PRESSURE (Ps) PSIA 455.00 515.00

ABSL. DISCHARED PRESSURE (Pd) PSIA 1,165.00 1,465.00

POWER REQUIRE HP 2,860 3,525

Injection gas flow at actual condition is 39.20 MMSCFD (87 % load) compare to design (45 MMSCFD) and power require is 2860 HP compare to 3525 HP

Table -5.3 : Performance of turbine 5000-PK-100

21-Dec-07 DESIGN

HP Turbine 5000-PK-100

HP turbine 5000-PK-100

A TURBINE

Fuel gas :

flow, MMSCFD 0.85 0.89

Flue gas :

Temperature, C 1,062 900

O2, % 15 16

Excess Air, % 234 279

Eff, % 22 27

Btu/BHP 11,460 9,392

CO2 emission :

Flow, lb/hr 2,217 2,450

B COMPRESSOR

Power Required, KW 2,134 2,630

, HP 2,860 3,525

Turbine is operated at 72 % load (2860 HP) compare to design (3525 HP) and heat rate is 11.460 Btu/HP compare to the design heat rate is 10500 Btu/HP.


Table -5.4 : Design performance of turbines

POWER,HP 4000 3500 3000 2500 2000 1500 1000

BTU/BHP 9500 9700 10500 11000 12000 12700 14000

LP Compressor 5000-PK-101

Table -5.5 : Performance LP Compressor 5000-PK-101 are as follows

UNITS ACTUAL DESIGN

INJECTION GAS MMCFD 6.00 15.00

ABSL.SUCTION PRESSURE (Ps) PSIA 75.00 75.00

ABSL. DISCHARED PRESSURE (Pd) PSIA 445.00 450.00

FUEL CONSUMPTION MCFD 250.00 400.00

POWER REQUIRE HP 533.05 1,439.09

ENERGY INTENSITY Btu/HP 19,541.46 11,581.36

LP compressor is operated at low load (less than 40 %) compare to design it will impact the energy intensity very high (19,541 BTU/HP compare design value 11,581 BTU/HP)

5.3 FINDINGS AND RECOMMENDATION

Findings :

A. Instrumentation

no flow gas meter for each gas consumer,

no control monitoring system that can be used to monitor the operation of the compressor from control room.

No meter indicators for electric equipments.

B. Compressor

Compressors is operated at low load for LP (less then 40%)


HP compressor is operated 70% load compare to design, the heat rate is higher then design heat rate at 70 % load.

LP compressors shut down frequently and causing increase of flare gas from 1 MMSCFD to 4-9 MMSCFD.


VI. PERFORMANCE MONITORING INDICATOR

6.1. EQUIPMENTS

6.1.1. Fired Heater

Function : converting energy from fuel gas into thermal in order to increase the temperature of process fluid

Key Performance Indicator :

Efficiency which is consist of combustion efficiency and heat transfer efficiency

Variable should be Measured :

% O2 in flue gas

Stack Gas Temperature

Ambient Temperature

Fuel gas flow, composition

Fuel gas heating value

Spread sheet :

See Appendix no.6.1

6.1.2. Waste Heat Boiler

Function : converting energy from fuel gas and permeat gas into thermal in order to produce steam and oxidize H2S from acid gas


Efficiency which consist of combustion efficiency and Heat transfer efficiency


% O2 in flue gas

Stack Gas Temperature

Ambient Temperature

Flow and composition of fuel gas, permeat gas and acid gas

Heating value of fuel gas, permeat gas and acid gas

Spread sheet :

See Appendix no.6.2


6.1.3. Gas Turbine Generator

Function : converting energy from fuel gas to mechanical energy to produce electricity


Efficiency which is consist of gas turbine efficiency and generator efficiency


Fuel gas flow (input)

Fuel gas heating value (LHV)

Generator Output

Oxygen content in flue gas

Flue gas temperature

Spread sheet :

See Appendix no.6.3

6.1.4. Gas Turbine Compressor

Function : converting energy from fuel gas to mechanical energy to compress sales gas


Efficiency which consist of gas turbine efficiency and compressor efficiency

Energy Intensity which is representing by fuel gas divided by mechanical energy to compress sales gas


Fuel gas flow (input)

Fuel gas heating value (LHV)

Oxygen content in flue gas

Flue gas temperature

Suction and discharge pressure of sales gas

Flow of sales gas

Spread sheet :

See Appendix no.6.4


6.1.5. Air Compressor

Function : converting energy from electricity to compress air


Actual power / Qs x ((Pd/Ps)^0.2857 – 1)

Note : Qs = air flow


Electricity power (input)

Pressure of compressed air

Spread sheet :

See Appendix no.6.5

6.1.6. Propane compressor

Functions : to evaporate refrigerant and to condense refrigerant vapor


Coefficient of Performance (COP)



Evaporation Temperature

Condensing Temperature

Spread sheet :

See Appendix no.6.6

6.1.7. Pumps

Functions : to transfer or to lift up the liquid


Efficiency which consist of pump efficiency



Liquid flow

Suction and discharge pressure

Spread sheet :


See Appendix no.6.7

6.1.8. Air Cooler

Functions : to cooling the fluid or to condense the vapor


Overall heat transfer coefficient (U)



Liquid flow

Temperature and Pressure of fluid inlet and outlet

Composition of fluid

Spread sheet :

See Appendix no.6.8

6.1.9. Heat Exchanger

Functions : to transfer heat from high temperature to low temperature of fluid


Overall heat transfer coefficient (U)


Fluid flow

Temperature inlet and outlet of hot side and cold side

Operating Pressure of hot side and cold side

Composition of fluid

Spread sheet :

See Appendix no.6.9


6.2. SYSTEM

6.2.1. TSA System

Functions : to reduce heavy hydrocarbon content of feed gas


Adsorption Rate

TSA Regeneration Rate


Feed gas flow

Temperature of feed gas

Pressure inlet and outlet gas

Composition of feed gas and outlet gas

Spread sheet :

See Appendices no.6.10

6.2.2. Membrane System

Functions : to reduce CO2 content of feed gas


Membrane separation rate

HC Slipped rate


mole CO2 in Permeate Gas

Mole CO2 in Feed Gas

mole HC in Permeate Gas

Mole HC in Feed Gas

Spread sheet :


6.2.3. Amine System

Functions : to reduce acid gas (CO2 & H2S) content of treated gas


A. Amine Contactor

Functions : to absorb acid in treated gas by amine liquid

Key Performance Indicator:

Absorbtion Rate

Variable should be measured:

mole-CO2 absorbed

Mole pure lean amine

Spread sheet :

See Appendix no.6.12

B. Amine Regenerator

Functions : to desorb/strip acid in rich amine by heating


Amine Regeneration Rate


CO2 content in lean amine and CO2 content in acid gas flow

Quantity of steam or fuel gas consumption

Operating temperature and pressure of regenerator

Spread sheet :


6.2.4. Dehydration System

Functions : to remove moisture in treated gas by glycol


Absorbtion Rate

Glycol Regeneration Rate


Flow of gas and glycol

water content inlet and outlet of treated gas

water content in lean glycol

Operating temperature and pressure of contactor

Spread sheet :



6.2.5. Dew Point Control System

A. Gas Chiller

Functions : chilling treated gas


COP (heat released by fluid divide by power of compressor unit)


Flow of sales gas and condensate

Composition of sales gas and condensate

Temperature inlet and outlet of chiller

Spread sheet :


B. Low Temperature Separator

Functions : to separate of sales gas and condensate.


Percentage of condensate content in sales gas compared to design value


Flow of sales gas and condensate

Composition of sales gas and condensate

Operating Temperature and Pressure of separator

Spread sheet :


6.2.6. Condensate Stabilizer

Functions : to remove light hydrocarbon from condensate.


Yield of Stabilization

Stabilizer Performance


Flow of raw condensate

Flow of treated condensate


Composition of condensate

Flow of steam

Operating Temperature and Pressure of column

Spread sheet :


6.2.7. Depropanizer

Functions : to produce propane.


Yield of Stabilization

Depropanizer Performance


Flow of feed to column

Flow of propane product

Electric consumption

Operating Temperature and Pressure of column

Spreadsheet:


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