Thermal Power Plant Auditing

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PRESENTATION ON ESSENTIAL REQUIREMENTS

FOR

ENERGY AUDITS

IN

THERMAL POWER STATIONS

BY

H.S.BediSr. Vice President (Power)

Energo Engineering Projects Ltd.A-57/4, Okhla Industrial Area,Phase – II, New Delhi - 110020

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““You cannot Manage what you You cannot Manage what you cannot Measure”cannot Measure”

(Accurately)(Accurately)

- Jack Welch, CEO, General Electric- Jack Welch, CEO, General Electric

PATTERN OF ENERGY CONSUMPTION

IN

THERMAL POWER STATION

4TYPICAL PLANT LOSSES

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SHORT FALL LOSS IN CRORES PER ANNUM

TURBINE CYCLE HEAT RATE 1.0 % 5.0

BOILER EFFICIENCY 1.0% 1.75

AUX. POWER CONSUMPTION 5.0 % 1.25

ECONOMIC ASPECTS OF INEFFICIENT

MACHINES (200 MW)

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REQUIREMENT – 1

1.1 ACCURACY OF COLLECTED DATA

– Collected data has to be most accurate & doubtless.

– Use calibrated and accurate instruments better conforming to ASME-PTC

standards

– 1.0% Error in data means unreliability and 25000 tons of coal loss/annum for

200 MW Unit or approx Rs. 5 crores / year based on assumption that

•TG cycle heat rate is taken as 2000 kcal / kwh

•Coal CV is taken as 4000 kcal / kg

•Price of coal taken as Rs. 2000 / ton

– Loss increases with machine size

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1.2 EFFECT OF INSTRUMENTATION ON ACCURACY

A. Plant on-line instruments with few audit instruments Accuracy around 3.0%.B. Accurate calibrated instruments as per ASME-PTC-6 for steam turbine& ASME-PTC-4-1 for Boilers. Accuracy around 0.5 %

1.3 EFFECT OF PROCEDURE ON ACCURACY OTHER THANASME-PTC-6 for steam turbines and ASME – PTC-4.1 for boiler

– Error in Boiler Energy Audit – around 2.0%– Error in steam turbine Energy Audit – around 3.0%

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1.4 TOTAL ERROR BECAUSE OF

INSTRUMENTATION & PROCEDURE

INACCURACY 6.0%

NOTE:DIFFERENCE IN COST OF ENERGY AUDIT BETWEEN AUDIT BY ACCURATE INSTRUMENTS AS PER ASME AND NORMAL INSTRUMENTS IS 12 TO 14 LACS AS AGAINST 6 TO 8 LACS.

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EFFECT OF INSTRUMENT INACCURACY ON HP/IP Turbine Efficiency

HPT Efficiency

Main Steam HPT ExhaustPressureKg/cm2

TempDeg C

PressureKg/cm2

TempDeg C

1 1 1 10.6 % 0.6 % 2.0 % 0.7 %

IPT Efficiency

IPT Inlet IPT ExhaustPressureKg/cm2

TempDeg C

PressureKg/cm2

TempDeg C

1 1 1 11.2 % 0.3 % 6.0 % 0.4 %

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EFFECT ON HEAT RATE FOR PARAMETER DEVIATION (500MW UNIT)

DEVIATION IN PARAMETER EFFECT ON HEAT RATE (KCAL/KWH)

1. HPT inlet press. by 5.0 ata 6.25

2. HPT inlet temperature by 10.0deg C 6.0

3. IPT inlet temperature by 10.0deg C 5.6

4. Condenser pressure by 10.0 mm of Hg

9.0

5. RH spray water quantity by 1.0% 4.0

6. HPT Cylinder efficiency by 1.0% 3.5

7. IPT Cylinder efficiency by 1.0% 4.0

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REQUIRED ACCURACY AND CALIBRATION OF THE INSTRUMENTS The proposed instruments should have following level of accuracy.

i. Thermocouples and PRTs – ASME special class ‘A’ i.e ½ DIN tolerance ii. Pressure and differential pressure - 0.1% transmitters better thaniii. Power Meter for generator & - 0.1%

Unit Aux Power measurementiv Data Logger - 0.03%v Power transducers / Load Analyser - 0.5%vi Flue gas analyser - 0.5%vii Ultrasonic flow meters - 0.5%viii Anemometer - 1.0%ix Infrared Thermometer - 1.0%x Lux meter - 1.0%xi RH meter - 1.0%

These should be duly calibrated from NABL accredited lab.The above accuracies for S.No. I to V are as per ASME specified for

Performance Evaluation of Thermal Power Plants.

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Economizer

FG

APH

SamplingLocations

FG

APH

ExpansionBellow

HVS

REQUIREMENT – IIPROPER SCHEMES FOR ENERGY AUDIT

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Annexure - IBOILER EFFICIENCY AND APH TEST SCHEME &

INSTRUMENTATION DIAGRAM 1. Grid measurement for gas composition and gas temp. at air pre heater inlet / outlet.

W/6 W/3 T1

W/3 T2

W/6 T3

N11 N21 N31

D/6

N12

N22 N32

D/3

N13 N23 N33

D/3

D/6

DEPTH

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ENERGY AUDIT SCHEME FOR 210 LMW STEAM TURBINE

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TURBINE CYCLE AUDIT

Pressure - 5 MinutesTemperature - 5 MinutesFlow - 1 MinutePower - 1 MinuteLevels - 10 Minutes

BOILER UNIT AUDIT

Temperature - 15 to 30 MinutesFlue Gas Composition - ½ to one hour

DURATION OF AUDIT TEST

Turbine Cycle - 2 HrsBoiler Unit - 4 Hrs

REQUIREMENT - III

FREQUENCY OF READINGS FOR ACCURATE DATA COLLECTION

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SCOPE OF WORK (SPEC) FOR ENERGY AUDIT OF A TYPICAL THERMAL POWER PLANT UNITS

A. BOILER• Boiler efficiency by heat loss method as per ASME PTC-4-1

guidelines and give break up of losses

• Furnace air ingress at different levels upto I.D.Fans

• Air heater performance Gas side efficiency Air side and gas side pressure drop across APH Air leakage across APH X – ratio i.e heat capacity of air to gas capacity.

• Aux power consumption and combined efficiency of fan and motors

of ID, FD & PA fans.

• Aux power consumption of coal mills, feeders vs loading.

REQUIREMENT – 4

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B. TURBINE1. Turbine cycle heat rate as per ASME-PTC-6 methodology and

instrumentation

2. HP and IP cylinders efficiency

3. Turbine pressure survey4. TTD & DCA of HP / LP heaters Pressure drop across heaters

5. Condenser performance i.e

Condenser back pressure after duly considering the effect of

present C.W inlet temp, C.W flow, heat load on condenser

and air ingress to condenser vis-à-vis design conditions

C.W side pressure drop in condenser

6. Cycle losses

7. Performance of turbine glands

8. Ejector performance

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C. ELECTRICAL SYSTEM

1 Motors Assessment of Loading condition of HT and LT motors of Boiler area, Turbine area and Balance of Plant area.

Assessment of operating parameters like load variation, Power factor of HT and LT motors consuming power more than 50 KW.

2 Capacitors Assessment of health of capacitors.

3 Plant Lighting system Lighting load survey and Assessment of installed load efficacy (I.L.E) and I.L.E ratio at various areas of plant.

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D. Pump performance for BFPs, CEPs, Aux C.W.P & C.W.P and

pumps consuming power more than 50 KW etc.

• Check Performance of the pumps by comparing the corrected

measured flow at operating speed to design speed with that of

the expected flow derived from the characteristic curves against

the corrected total dynamic head at design speed.

• Determine Pump efficiency as the ratio of power input to the

pump shaft to hydraulic power.

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E Insulation Audit:A. Walk through survey of Boiler, Turbine and associated steam

piping to identify the damaged and Hot spot area.B. Surface temperature measurement at the damaged and Hot

spot area by infrared temperature indicator.C. Estimation of heat loss in the hot spots and damaged

insulation area. F Balance Of Plant(i) Compressed air system:• Free Air Delivery i.e. Capacity evaluation of the Plant and

Instrument air compressors.• Checking volumetric efficiency of compressors.• Assessment of compressed air leakage quantity.

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(ii) Air conditioning system:

• Performance evaluation of AC Plant w.r.t net cooling /

refrigeration capacity along with heat load of Air handling unit and

energy requirements.

(iii) Ash Plant

• Performance of ash Slurry pumps through power measurement

and flow measurement.

• Ash water ratio assessment and recommendations for

optimization in water and power consumption.

(iv) Cooling Tower Performance

It shall include establishment of

• Liquid/Gas ratio

• Cooling tower effectiveness, approach and range

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(V) Coal Handling Plant

Input Power measurement of all the key equipment of the CHP area

like: Paddle feeders, Conveyors, Stacker & Re-claimer, Wagon

Tipplers, Crushers,

NOTE:

• ENERGY CONSERVATION MEASURES TO BE SUGGESTED

IN ALL THE ABOVE AREAS OF AUDIT.

• ENERGY AUDIT PROCEDURE TO BE SUBMITTED ALONG

WITH AUDIT MEASUREMENT SCHEMES AND APPROVED

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1.0 USEFULNESS OF ENERGY AUDIT IN THERMAL POWER STATION • Identifies wastage areas of fuel, power and water utilization.• Reduction in cost of generation by implementing findings of EA.• Increases power generation by efficient utilization of steam in turbine

cycle and reduction in Aux Power Consumption.• Maintenance planning and availability improvement.• Provides guidance in loading sequences of the units. • Identification and rectification of errors in on-line instruments.• Leads to reduction in green house gases. • Utilizes specialized services of experienced engineers.• Training of O&M staff for efficient control of unit operation.• Improves competitiveness by reducing unit generation. • Creates bench mark for all equipments and systems.• Fulfills bureau of energy efficiency mandatory requirement of Energy

Audit.

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1) Operation of machine at very low turbine I/L parameters.

2) Operation of turbine at lower loads.

3) HP and IP turbine cylinder efficiencies are very low.

4) Main steam and HRH inlet temperature to turbine very low.

5) RH pressure drop high.

6) High quantity of SH Spray and its tapings before HPH-5 resulting in loss of heat because of changed cycle.

METHODS / OBSERVATIONS FOR SAVINGS ENERGY IN POWER PLANT

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7) HP heater no. 5 out of service.

8) Turbine cycle not operating as per design scheme i.e. Ejector and Deaerator pegging steam from PRDS header as against normal source from deaerator & extraction steam respectively.

9) Passing of turbine cycle drain valves.

10) Make up quantity to cycle is very high which indicates

excessive system steam (heat) loss.

11) TTD & DCA of heaters high.


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12) Condenser air ingress and dirty tubes.

13) Under loading of motors

14) Excessive air leakage in compressed air system

15) Faulty insulation

16) Drain valves passing

17) Air ingress to Boiler furnace

18) FAD of compressors low


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Thanks…Energo Engineering Projects Ltd.A-57/4, Okhla Industrial Area, Phase – II Phone: +91 - 11 - 26385323/ 28/ 29/ 38Fax: +91 – 11 – 26385333E-mail: [email protected] [email protected]: www.energoindia.com

Thermal Power Plant Auditing

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