6 EnvironmentalAuditofTPP-Final BRN

ENVIRONMENTAL AUDIT OF COAL FIRED THERMAL POWER PLANTCOAL FIRED THERMAL POWER PLANT

– A CASE STUDY

B R NaiduB. R. Naidu

Zonal Officer (West)

CPCB, Vadodara

Presentation Contents

Environmental Audit of Thermal Power Plant (TPP) – A Different Approach

Features of Coal Based Thermal Power Plant

I S i f E i l A di F f Important Sections of Environmental Audit Format for Thermal Power Plant

• General

• Product Details

• Water

• Air

• Hazardous (Solid) Waste

• R R• Resource Recovery

Summary of Env. Audit of TPP

Environmental Audit of Coal based TPP A “Different Approach” than for other chemical manufacturing industries

1 Product is Electricity which can not be stored1. Product is Electricity, which can not be stored.

2. Basic raw materials are Solid fuel, water and water treatment chemicalstreatment chemicals

3. By product is ash and heat

4. Highly water intensive industry

5. Material mass balance for Water, Coal and Heat can b dbe prepared

6. High Potential of Air Pollution while that is low for water as water is primarily used for cooling water as water is primarily used for cooling purposes.





• General

• Product Details

• Water

• Air





Product : Electricity

Product Unit MW

Basic Raw Materials Solid fuel (Lignite/coal), Water

Process Burning of coal converting ‘C’ to CO2

By Product Heat and Ash

M t i l M C l H t d W t B lMaterial Mass Balance

Coal , Heat and Water Balance

Type of Industry Water Intensive yp yPrimary use: for cooling purpose

P ll ti P t ti l Ai V Hi h W t l Pollution Potential Air : Very High ; Water : low





• General

• Product Details

• Water

• Air




Section - A] General]

• Electric Consumption per unit of the product i.e. ElectricityElectric Consumption per unit of the product i.e. Electricity

• “Auxiliary Electric Consumption” – Usually 10%

Study Plant – 0.093 kwh/kwh generatedy 9 / g- i.e. 9.3%





• General

• Product Details

• Water

• Air




Section - B] Product Details

• Electricity has to flow or to be utilized

• Plant Load Factor (PLF) = Actual power generated

Installed capacityInstalled capacity

• PLF varies from station to station and time to time

‘A l d il f PLF’ f l t d t d i 0 823

depending upon the operating conditions

‘Annual daily average of PLF’ for plant under study is 0.823

Section - B] Product DetailsSection - B] Product Details…

• Identification and Consumption of Raw Materials per unit of production

Basic Raw Materials

Fuels Water

CoalI di

Liquid Fuels•Indigenous•Imported

q•HSD

•Residual Fuel Oil

Section - B] Product Details…]

• Liquid fuel quantity is negligible required only for Liquid fuel quantity is negligible required only for start-up operation

A l ti it f • Average coal consumption per unit of power generated is important.

Coal Consumption Per Unit of Power Generated (Kg/unit)

Sr. No. Month Unit - I Unit - II1 January 0.685 0.5012 February 0.691 0.4983 March 0.706 0.5104 April 0.699 0.5165 May 0.646 0.4536 June 0 707 0 5146 June 0.707 0.5147 July 0.711 0.5138 August 0.706 0.525

b9 September 0.683 0.48910 October 0.660 0.49011 November 0.624 0.46912 December 0.637 0.299

Yearly Average 0.679 0.498

For Plant under study – at one of the station coal Consumption was 50% more than the other stations.

Section - B] Product Details…

l d l d• Coal consumption and total energy consumed

should be compared to establish a useful

relationship to identify deviation, if any.

Energy Consumed (Kcal supplied by coal/KWH)

Sr. No. Month Unit - I Unit - II1 January 3800 32002 February 3830 25863 March 3900 23604 April 3880 34404 April 3880 34405 May 3590 22306 June 3800 2900

l7 July 3940 27238 August 3887 26809 September 3795 257710 October 3631 261211 November 3436 254912 December 3186 164312 December 3186 1643

Yearly Average 3723 2625

Section - B] Product Details…]

• Determine turbine efficiency at different stations

• Overall plant efficiency can also be calculated and

compared against design value

Overall Energy Consumption – 2911.3 Kcal/Unit

Designed Energy Consumption – 2450 Kcal/Unit

Overall Plant efficiency – 29.5%

Designed efficiency – 35.1%

Section - B] Product Details…Coal (1401 T/day) On a Given Day

Moisture Content

Carbon Content

Sox1 401

Volatiles567 4

Non CombustibleContent

267.6Content

484.21.401 567.4 Combustible

80.4

dConverted to CO2478.8

Unburnt Carbon in the

gases5.4

Ash59.4

Reject21.0

Fly Ash47.5

Bottom Ash11.9

Collected & Disposed off to

ash ponds

Lost with flue gases

2.22

Utilized directly

20.0

Coal Balance Diagram

p25.28

Section - B] Product Details…Heat Units Supplied by Coal

Heat Contained in Feed Water (Recovered Heat)

by Coal7.12 x 109

2.73 x 109

Economizer LPH inlet to Air PreheaterEconomizer0.66 x 109

LPH inlet to HPH outlet

1.49 x 109

Air Preheater0.58 x 109

Total Recovered Heat Input2.73 x 109

Total Heat Input 9.85 x 109Total Heat Input 9.85 x 10

Heat contained in the steam

7 6 x 109

Losses1.53 x 109

Heat Lost with Flue gases0 72 1097.6 x 109 0.72 x 109

Power generated2.3 x 109 Heat Lost at

Cooling TowerOther Losses

0.12 x 109

5.18 x 109

Heat Balance Diagram (Unit : Kcal)

Salient Points of Heat Balance DiagramSalient Points of Heat Balance Diagram

• Source of Heat Input – Coal and Recovered Heat

• The unit is recovering 2.73 x 109 kcal/day i.e. 24.71% of the total heat input

• Heat recovery is done by economizer, low pressure heater and high pressure heater

• % conversion to useful energy i.e electricity –23.35% of total heat input

• Energy lost to the environment – 76.65%

• Numerically the energy converted to electricity is Numerically the energy converted to electricity is equal to the recovered heat





• General

• Product Details

• Water

• Air




Section - C] Water]

General Water Requirements

Water Requirements

Cooling Tower Water Boiler Feed Water

D i d Q lit Domestic & Other Uses

D ti S l t C lDesired Quality -Soft Water

-Softening Plant

Desired Quality -Demineralized Water

- DM Plant

- Domestic Supply to Colony- Spraying on Coal at Coal

yard- Gardening

Section - B] Product Details…Total Water Withdrawal

47,158 m3/day]

Cooling System28 399

Process (Boiler)2 116

Domestic and Other Uses16 64328,399 2,116 16,643

Make up Regenerant Make up RegenerantMake up26,959

Regenerant1,440

Make up1,576

Regenerant540

Colony Domestic Coal Yard & U i

Blow LossesBlow Evaporation & Colony3,802 inclusive of

Floor Wash96

Use in Gardening

12,745

To DrainsTo Neutralization Pit, 540

Down80

Losses1,496Down

8,423Drift Losses

18,536

Final Holding Pit 8 423

To Catch Pit

Water Sump 8,963

Ash Slurry Sump 10 579 Seepage Evaporation 5 009Ash Ponds 5 574Receiving Water Body

Final Holding Pit, 8,423

Ash Slurry Sump 10,579 Seepage Evaporation, 5,009Ash Ponds 5,574Receiving Water Body

Water Balance Diagram

Analysis of Water Balance Diagram

Total Water Quantity = 47,158 m3/day

• No. of water withdrawing stations / borewells – 20

R f i l h t i t i d t d HP •Referring log sheets maintained to record pump HP, Pump Discharge, No. of pump running hrs, etc.

•Total quantity pumped, = [ No. of pumps x yield of m3/day pump, m3/hr x no. of

operational hrs, hrs/day ] p , / y ]

For Plant under study – water used per unit of Power Generated = 5 36 LPower Generated = 5.36 L

Analysis of Water Balance Diagram…

Pump Discharge – very imp.

y g

A] Three approaches of Field Measurement :

(1) Use of ultrasonic flow meters

(2) Requires actual measurement of ‘H’ over the ‘V’ ( ) qNotches

Q = (8/15) Cd tan(θ/2)(2g)1/2H5/2

(3) Actual Measurement of Discharge from Pump Discharge Line. = Measured Volume/Time


B] Field Measurement and Theoretical Calculation :

y g

(4) Power Consumption by Pump

Kw = 1.73 Vi Cosø

= 1.73 Vi PLF---------------Eq.1

Where, Vi = Consumed current in Ampere measured by Ampere meter

PLF = Plant Load Factor


(4) Power Consumption by Pump […..Continue]

y g

Substitute the value of Kw (HP) in Eq.2 to calculate Q

B.H.P = W x Q X H -----------------------Eq. 2

75 η

i.e., Q = B.H.P x 75

W x H

Where, B.H.P = Break Horse Power W = Density of water, 1000 Kg/m3; H = Total Head (suction + discharge) m H = Total Head (suction + discharge), m

η = Pump Efficiency


Cooling Water 28,399 m3/day

Make Up Water, 26,959 Softening plant regeneration Water, 1440

Bleed – off, 8423

•Water for final di l

Evaporation and Drift losses, 18,536

1 2 % f l i

• Quantity depends upon the design and disposal

•Depends on COC

•COC – 3 (usually)

•1.2 % of total water in circulation for natural draft CT

1 5% f t t l t i

the design and operation of the plant

( y)

•COC up to 6 can be achieved by addition of chemicals to lower

•1.5% of total water in circulation for induced draft fan

down the quantity of w/w to be disposed off


Boiler Feed Water, 2116 m3/day

Make-up Water , 1576 Regeneration water from DM Plant, 540

Blow Down, 80

•3 5% of make up Other Losses, 1496

• Depends on design and operating parameters of DM

•3 – 5% of make-up water

•To get the quantity deduct blow down from total Boiler make-up water quantity

plant

up water quantity


Domestic and Other Uses = 16, 643 m3/dayDomestic and Other Uses 16, 643 m /day

To get the quantity for Domestic and other uses :

Domestic + other uses = Total Quantity – (CT + Boiler Make up)

= 47,158 – (28,399 + 2,116)

= 16,643 m3/day





• General

• Product Details

• Water

• Air




Section - D]: Air

• Source - Flue gas stacks

]

• Monitoring Parameters: PM, SO2, NOx

• PM control is imp for coal/lignite based thermal • PM control is imp. for coal/lignite based thermal

power plant

• The unit under study has installed ESP for each

power generating station

Determination of ESP Efficiency and Operating conditions

• Sampling at Inlet and Outlet of ESP

Results of Flue Gas Analysis

Sr. No.

Parameter Unit - I Unit - IIInlet Outlet Inlet Outlet

[A] PARTICULATE MATTER1 Stack Flue gas temp. (Deg.

C)144 131.00 144.00 124.00

2 Volume of gas sampled at NTP ( )

0.174 0.591 0.162 0.582NTP (cu.m)

3 Wt of SPM collected (mg) 3675.57 274.22 2516.20 178.68[B] GAS CONCENTRATION

DATADATA4 Particulate Matter (PM)

mg/Nm321124 464 15532 307

5 Sulphur Dioxide (SO2) 134 75 102 49p ( 2)mg/Nm3

6 Nitrogen Dioxide (NO2) mg/Nm3

3 3 2.5 2.0

Sr. No. Parameter Unit - I Unit - II

PM REMOVAL EFFICIENCY OF ESP

I II III I II III

1 Avg. Inlet Conn

21124 13465 23225 15532.1 18986 13500

2 Avg. 464 87.55 464.5 102.4 111 1352 Avg. Outlet Conn

464 87.55 464.5 102.4 111 135

3 Removal Efficiency

97.80 99.34 98.00 99.34 99.41 99.0

4 Designed 99.77 99.77 99.77 99.37 99.37 99.37gRemoval Efficiency

5 % (-) 1.97 (-) 0.43 (-) 1.77 (-) 0.03 (-) 0.04 (-) 0.37Deviation

I – 1st Monitoring, II – 2nd Monitoring, III – 3rd Monitoring

Section - D]: Air

• For study plant ESP efficiency – 99% plus - near the

]

design value

• One Exceptional power station with efficiency –

97% (200% Deviation from GPCB Norms)

• Reduced Efficiency due to 4 out of 10 operational

ESP fields

Section - D]: Air]

• Interesting Observation –50-60% decrease in SO2 in

ESP

• For Nox – Catalytic Burners installed – The values

found within prescribed limitsp





• General

• Product Details

• Water

• Air




Section - E]: Hazardous Solid Waste

Ash :

]

(1) Fly Ash and

(2) Bottom Ash( )

• Source – Solid FuelSource Solid Fuel

• Study plant uses blend of indigenous coal with Study plant uses blend of indigenous coal with high ash content and also imported coal with low ash content

Section - E]: Hazardous Solid Waste

• Two Types of Fly Ash Collection Systems

]

(1) Dry System – Collected ash sold or utilized

(2) Wet System Through Fly ash ponds(2) Wet System – Through Fly ash ponds

- Overflow of the pond is discharged to riverg

18% utilization of fly ash collected within the study plant

Coal Balance diagram can be used to calculate the theoretical quantities to verify the actual quantities of ash.





• General

• Product Details

• Water

• Air




Section - F]: Resource Recovery] y

Source of Resource Quantity Recovery Recovery

y ySystem

APC system Fly Ash 18% utilization

Dry and Wet Systemutilization

of total quantity

System

P B A h 15% f l M l Process (Boiler)

Bottom Ash 15% of total quantity

Manual Collection

Process Heat 2.73 x 109 Economizer, kcal/day

,Low Pressure Heater, High Pressure Heater





• General

• Product Details

• Water

• Air




Summary of Environmental Audit of TPPy

Sec. No

Description Particulars Study Plant Values

Reference Records No. Values Records maintained at the Plant

A General Electric Auxiliary Electric Electricity A General Electric Consumption per ton of product

Auxiliary Electric Consumption = 0.093 kwh / kwhgenerated

Electricity Bills

p gB Product

DetailsProduct and the raw materials

-Annual Daily average of PLF = 0.823

Log sheets maintained at production

required per unit of production

- 29.5% of Energy Efficiency against 35.1% of design

pfloor

gvalue


Sec.No.


Reference Records maintained at the Plant

C Water Quantity, Total Quantity = Pumping yWater Treatment, W/W

y47,188 m3/day

Water Balance

p ghrs, Discharge, Log Sheets

generation, ETP details, adequacy of ETP

Water Balance Diagram maintained

for DM Plant and S ft i ETP,

Compliance with GPCB norms

Softening Plant

norms


Sec.No



D Air Stacks, Flue 99% plus ESP Actual D Air Stacks, Flue gases, APC system, ESP Efficiency

99% plus ESP efficiencyOne exception station with 97%

Actual Monitoring of Parameters at Inlet and y

and operating conditions,

station with 97%50-60% SO2reduction in ESPNox is under

Outlet of ESP using Stack Monitoring

Nox is under control as catalytic burners installed

Kit.

installed

Summary of Environmental Audit of TPPSummary of Environmental Audit of TPP

Sec. No.


Reference Records maintained

h Plat the PlantE Hazardous

Solid WasteSource, Quantity,

1.56 MT/MW Log sheets, Ash

Method of collection Storage and Di l

collection data, Coal Balance DiDisposal Diagram


Sec. No



F Resource Fly Ash from 18% of total fly Log sheets, F Resource Recovery

Fly Ash from the APC system, Heat from the

18% of total fly ash utilized from APC system

Log sheets, records, Heat Balance Diagram

Heat Recovery System

y15% of bottom ash recovery 2.73 x 109

g

2.73 x 10kcal/day of heat recovery

6 EnvironmentalAuditofTPP-Final BRN

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