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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.
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
Features of Coal Based Thermal Power Plant
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
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
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%
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
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
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
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
Analysis of Water Balance Diagram…
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
Analysis of Water Balance Diagram…
(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
Analysis of Water Balance Diagram…
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
Analysis of Water Balance Diagram…
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
Analysis of Water Balance Diagram…
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
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
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
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
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.
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
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
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
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
Summary of Environmental Audit of TPPy
Sec.No.
Description Particulars Study Plant Values
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
Summary of Environmental Audit of TPPy
Sec.No
Description Particulars Study Plant Values
Reference Records No. Values Records maintained at the Plant
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.
Description Particulars Study Plant Values
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
Summary of Environmental Audit of TPPy
Sec. No
Description Particulars Study Plant Values
Reference Records No. Values Records maintained at the Plant
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