![KHAPERKHEDA THERMAL POWER STATION
Note : It is assumed that total ash generated contains 80 % fly ash & 20 % of it is
evaluated as bottom ash.
Total Unburnt in ash (U) = ( UF + UB ) Kg / Kg.
Loss = ( Total Wt. of carbon ) * ( Calorific value of carbon in Kcal / Kg ) * 100
Calorific value of coal (fired)
= U * 8077.8 * 100
CVCF
L -1 = 2.0 % (designed)
Note CV of carbon is assumed to be 8077.8 Kcal / Kg.
(2) Loss due to moisture in fuel : L -2
Sensible heat of water vapor= SHWV
= { 1.88 (Tgo – 25) } + 2442 + {4.2 (25 – Tamp)}
= SHWV KJ / Kg.
Where, Tgo Temp of gas at AH exit
Tamp Ambient temp ( dry bulb )
Loss ( L– 2 )= [ Sensible heat of water vapour ] * [ Moisture in coal as fired ]
Calorific Value of coal as fired
= SHWV * MF % { 1Kcal = 4.1868 KJ }
4.1868 * CVCF](https://image.slidesharecdn.com/heatratecalculations-june08-250124120239-69a7b202/85/HEAT-RATE-CALCULATIONS-for-turbines-JUNE08-ppt-18-320.jpg)
HEAT RATE CALCULATIONS for turbines -JUNE08.ppt
- 1. KHAPERKHEDA THERMAL POWER STATION Executive Engineer (OS)
- 2. KHAPERKHEDA THERMAL POWER STATION Heat rate is the amount of chemical energy that must be supplied to produce one unit of electrical energy. Heat rate is a measure of how efficiently it converts the chemical energy contained in fuel into electrical energy. Since, coal chemical energy is measured in kilocalories (kCal) and electrical energy is measured in ‘unit’ i.e. kilowatt-hours (kWh), the units of heat rate are kilocalories per kilowatt-hours (kCal/kWh). Empirically, 1% improvement in efficiency is equal to 3% improvement in heat rate.
- 3. KHAPERKHEDA THERMAL POWER STATION DESIGN HEAT RATE = 2275 KCAL/KWH FOR U 1 & 2 DESIGN HEAT RATE = 2234 KCAL/KWH FOR U 3 & 4 STATION AVERAGE = 2255 KCAL/KWH DESIGN HEAT RATE
- 4. KHAPERKHEDA THERMAL POWER STATION Actual heat rate is calculated by conducting test. Boiler efficiency is calculated by loss method. Boiler efficiency = 100 – losses in % Turbine heat rate is calculated by taking heat balance across turbine. Unit heat rate = Turbine heat rate Boiler efficiency This heat rate of unit on as fired basis (AFB) correctly denotes and is indicative of – “How efficiently unit is running”
- 5. KHAPERKHEDA THERMAL POWER STATION Input data:- At 210 MW MS pr. at HPT in bef. ESV : 150 Kg/cm2 MS temp. at HPT in bef. ESV : 535 o C Total Steam Flow : 627 T/Hr FW temp at HPH 6 outlet : 244 o C Total feed flow : 627 T/Hr MS pr. at HPT outlet bef. NRV : 38 Kglcm2 MS temp. at HPT outlet bef. NRV :338 o C MS pr. at IPT inlet before IV : 34 Kglcm2 MS temp .at IPT inlet before IV : 535 o C RH spray flow (Left & right) : 0 T/Hr HPH-6 drain temp (drip) : 207 o C HPH-5 outlet temp of FW : 201 o C Hp heaters out of service (5/6) : Nil HPH-6 Extn. Value EX-12(Open/Close) Open Steam extr. pr. to HPH-6 : 36 Kglcm2 ab Steam extraction temp at HPH-6 : 337 o C Load : 210 MW Aux cons. (Uat + Stn.) Barometric pr. : 735.6 mm of Hg Ex-301/CR-306 Dearator heating : Close
- 6. HPT BOILER OUTLET PRDS 1 IPT LPT COND RH HPH-5 BFP LPH 1,2,3 HPH – 6 ECO RH SPRAY 4 1 2 RH SPRAY DRTR 2 3 CR 306 EXTN - 6 EXTN - 5 EXTN – 4 EX 301 EXTN – 1,2,3 CEP At 210 Mw (1) (2) (3) (4) Press. (Kg/cm2 ) 150 38 34 187 Temp. (o C) 535 338 535 244 H-Enth. (Kcal/kg) 814 734 843 253 Flow (T/Hr ) 627 565 565 627
- 7. KHAPERKHEDA THERMAL POWER STATION First all pr. To be converted from gauge to absolute values e.g. Ms. Pr.=149 kg / cm2 (g) =149 +(735.6 / 735.6)kglCm2 (ab) Absolute = gauge + atmospheric. (1) Heat in steam at HPT inlet = kcal/Hr. QHPTI = Steam flow * Enthalpy of steam ( from steam table based on pr. & temp. ) = (Total steam flow – PRDS flow ) *1000 * Enthalpy = (627 - 0) * 814 * 1000 kcal /Hr = 510.378 * 106 kcal /Hr. (2) Heat in steam at HPT outlet = QCRH kcal / Hr. QCRH = CRH flow * 1000 * Enthalpy of steam (from steam table based on pr. & temp.) = 565 *1000 *734 kcal / Hr = 414.710 * 106 kcal /Hr CRH flow =(Steam flow at HPT inlet ) - (HPT gland leakage flow) – (Extraction flow to HPH-6) = 627 – 6 – 56 = 565 T/Hr. (HPT Inlet + outlet ) HPT gland leakage flow – a function of steam flow
- 8. KHAPERKHEDA THERMAL POWER STATION Steam extraction flow to HPH-6 to be taken as ‘ 0 ‘if HPH-6 is out of service (Ex-12 closed) Otherwise to be obtained from heat balance equation. Heat removed from the steam in HPH-6 = Extr-6 flow * (H1 – H2) H1 - Enthalpy based on extraction 6 pr. And temp. (734 kcal / kg based on P = 36 kg / cm2 ab and T = 337 c) H2 - Enthalpy of HPH-6 drain at 207 o C ( H2 = 212 K/k ) Heat gained by the feed water in HPH-6 = Flow *(H3 – H4) = 627 * ( 253 – 206 ) Where H3 = Feed enthalpy at HPH - 6 outlet at 244 o C H4 = Feed enthalpy at HPH - 5 outlet at 201 o C Now equating heat removed = heat gained . i.e. Extr-6 flow * ( H1 – H2 ) = Feed flow * ( H3 – H4 ) Comes around 56 T /Hr at 210 MW. 4 HPH-6 HPH-5 3 2 1
- 9. KHAPERKHEDA THERMAL POWER STATION (3) Heat in steam at IPT inlet = QHRH kcal / Hr. = HRH flow * 1000 *HRH enthalpy (from steam table based on HRH pr. & temp.) Now , HRH flow = ( CRH flow ) – ( flow through CR-306 ) + ( RH spray flow) = 565 – 0 + 0 ( if CR-306 is closed, normally dearator heating = 565 T / Hr. is from Extn-4 { Ex. 301 open} ) QHRH = HRH flow * HRH enthalpy at P= 37 , T = 535 o C = 565 * 843 * 1000 kcal / Hr = 476.295 * 106 kcal / Hr (4) Heat in feed water at HPH-6 outlet = QFW = Feed flow * Feed enthalpy at T= 244 o C = 627 * 253 * 1000 kcal / Hr =158.631 * 106 kcal / Hr Net Heat used in turbine = QHPTI – QCRH + QHRH – QFW Kcal / Hr = ( 510.378- 414.710+476.295- 158.631)*106 kcal / Hr = 414 *106 kcal / Hr ( 413.70 * 106 )
- 10. KHAPERKHEDA THERMAL POWER STATION Generated MUS = 210 / 1000 = 0.21 Mkwh. = 0.21 * 106 Kwh T/G Heat Rate = Net heat used in turbine Generated MUS = 414 * 106 = 1970 Kcal / Kwh 0.21 * 106 = T/ G heat Rate Corrected T / G heat rate is the gross T/G heat rate corrected to designed parameters (MS pr. temp at HPT inlet , HRH temp, condenser vacuum & % Reheater pr. Drop ) Corrected T / G HR = 1970 Kcal / kwh.
- 11. KHAPERKHEDA THERMAL POWER STATION Boiler Efficiency is defined as the ratio of boiler heat output to its input. Boiler heat output can be calculated as the heat input less total losses. So boiler efficiency is calculated by indirect method. It indicate the status of boiler performance. Boiler efficiency = Boiler Output * 100 Boiler Input Boiler Output = Boiler input – Total losses. = 100 – 13.39 = 86.61 % (at 210 Mw) (Designed) Boiler Efficiency = ( Boiler Input – Total losses ) Boiler Input = 100 – 13.39 * 100 100 = 100 – 13.39 = 86.61 % {Expected at 210 Mw }
- 12. KHAPERKHEDA THERMAL POWER STATION 1 ) Proximate analysis of coal is to be carried out by the chemist by taking samples of coal from coal feeder. From this analysis various coal contents & calorific value of coal are obtained . ( 2 ) Flue gas analysis :- It is to be carried out by the chemist by taking samples from air heater inlet / outlet with the help of Orsat apparatus. Percentage of oxygen & carbon dioxide contained in flue gas at these points are obtained from such analysis . ( 3 ) Unburnt in fly ash &bottom ash :- Samples are collected from bottom ash hoppers & fly ash hoppers. After its analysis by the chemist percentage of unburnt carbon in fly & bottom ash is obtained . ( 4 ) Dry bulb temperature & wet bulb temperature near FD Fan are provided by the chemist. Based on these temperatures specific humidity & relative humidity of air are to be obtained from psychometric chart which is enclosed herewith .
- 13. KHAPERKHEDA THERMAL POWER STATION Input data required for calculating boiler efficiency :- Expected values (210 Mw) (1) Main steam flow at boiler outlet flow ( TSF) - 627 T/Hr. (2) Flue gas temp at Air heater outlet, (Tgo) - 141 o C (3) Ambient temp. ( Tamb ) - 38 o C (4) Wet bulb temp - 30.5 o C (5) Relative humidity - 60 % (6) Specific humidity - 0.025 Kg / Kg. (7) Oxygen in flue gas at AH inlet - 3.50 % (8) Oxygen in flue gas at AH outlet - 6.0 % (9) Carbon dioxide in flue gas at AH outlet (CO2) - 14.80 % (10) Unburnt % in bottom ash (%) - 4.0 – 5.0 (11) Unburnt % in fly ash (%) - 0.4 – 1.0 (12) Carbon dioxide in flue gas at AH inlet - 15.90 % Basic Input Proximate Analysis – ( Air dried basis ) (1) Moisture content in coal (%) - MD (2) Ash content in coal (%) - AD (3) Volatile matter in coal (%) - VD (4) Fixed carbon in coal (%) - CD (5) Calorific value of coal in kcal / kg (%) - CVCD (6) Moisture content in coal on as fired basis - MF
- 14. KHAPERKHEDA THERMAL POWER STATION Note – Above coal analysis given on dried basis to be converted correspondingly on as fired basis as per following procedure. Calorific value of coal(as fired) (CVCF) = 100 – Moisture (Fired) * CV of coal dried CVCD 100 – Moisture (dried) Likewise, Ash, volatile matter & Fixed carbon are to be obtained on as fired basis. Designed Values Proximate analysis ( As fired basis ) MF – Moisture - 10 % AF - Ash - 29 % CF - Fixed carbon - 35 % VF - Volatile hatter - 26 % CVCF - CV. Of coal - 4400 kcal / kg
- 15. KHAPERKHEDA THERMAL POWER STATION DATE AIR DRY BASIS AS FIRED BASIS M% ASH% VM% FC% GCV (KCAL/KG) M% ASH% VM% FC% GCV (KCAL/KG) BUNKERED COAL SAMPLE OF UNIT NO .I 16.06.08 5.14 45.82 22.14 26.90 3470 16.01 40.57 19.60 23.82 3072 BUNKERED COAL SAMPLE OF UNIT NO .II 16.06.08 4.72 45.51 22.31 27.46 3541 16.12 40.06 19.64 24.17 3117 BUNKERED COAL SAMPLE OF UNIT NO .III 16.06.08 5.65 41.69 23.17 29.49 3759 15.51 37.33 20.75 26.41 3366 BUNKERED COAL SAMPLE OF UNIT NO .IV 16.06.08 4.94 41.40 23.28 30.38 3813 15.94 36.61 20.59 26.86 3372 AVERAGE OF BUNKERED COAL 16.06.08 5.11 43.61 22.73 28.56 3646 15.90 38.64 20.14 25.32 3232 Diff ADB - AFB = 414
- 16. KHAPERKHEDA THERMAL POWER STATION Ultimate Analysis of Coal – ( 1 ) Total Carbon in Coal ( % ) :- TCF = ( Fixed Carbon ( dried ) + 0.9 (VD – 14) ) * CVCF CVCD = ( CD + 0.9 ( VD – 14 )) * CVCF CVCD = 47 % ( designed ) ( 2 ) Sulphur Content in Coal ( % ) :- SF SF = SD * CVCF CVCD = 0.6 % (designed) (3) Hydrogen Content in Coal :- H2F H2F = VD * 7.35 – 0.013 * CVCF (VD+10) CVCD = 3 % ( designed ) (4) Nitrogen Content in Coal :- N2F N2F = 2.1 – { 0.012 * VD } * CVCF CVCD =1 % ( designed )
- 17. KHAPERKHEDA THERMAL POWER STATION (5) Oxygen Content in Coal : O2F O2F = 100 – AF + MF + TCF + SF + H2F + N2F = 100 – 29 + 10+ 47+ 0.6+ 3+ 1 = 100 – 90.6 = 9.4 % (designed) CALCULATION of LOSSES :- (1) Loss due is unburnt Carbon :- L-1 Unburnt Distribution Ash Content Unburnt in Carbon = of fly ash ( %) * in Coal as fired ( % ) * fly ash (%) in fly ash 100 100 100 Kg/Kg of Coal = UF Kg / Kg of coal Unburnt Distribution Ash Content Unburnt in Carbon = of bottom ash (%) * in Coal as fired (% ) * bottom ash (%) in bottom ash 100 100 100 Kg/Kg of Coal = UB Kg / Kg of coal
- 18. KHAPERKHEDA THERMAL POWER STATION Note : It is assumed that total ash generated contains 80 % fly ash & 20 % of it is evaluated as bottom ash. Total Unburnt in ash (U) = ( UF + UB ) Kg / Kg. Loss = ( Total Wt. of carbon ) * ( Calorific value of carbon in Kcal / Kg ) * 100 Calorific value of coal (fired) = U * 8077.8 * 100 CVCF L -1 = 2.0 % (designed) Note CV of carbon is assumed to be 8077.8 Kcal / Kg. (2) Loss due to moisture in fuel : L -2 Sensible heat of water vapor= SHWV = { 1.88 (Tgo – 25) } + 2442 + {4.2 (25 – Tamp)} = SHWV KJ / Kg. Where, Tgo Temp of gas at AH exit Tamp Ambient temp ( dry bulb ) Loss ( L– 2 )= [ Sensible heat of water vapour ] * [ Moisture in coal as fired ] Calorific Value of coal as fired = SHWV * MF % { 1Kcal = 4.1868 KJ } 4.1868 * CVCF
- 19. KHAPERKHEDA THERMAL POWER STATION (3) Loss due to hydrogen in fuel • = 9 * ( Hydrogen Content in coal as fired ) * ( Sensible heat of water vapour ) • Calorific Value of Coal • = 9 * H2F * SHWV % • CVCF 4.1868 • ∴ Loss due to total moisture in fuel ( L – 2 ) • = ( Loss due to free moisture in fuel ) + (Loss due to hydrogen in fuel ) • L - 2 = 5.23 % ( design) (4) Loss due to moisture in air ( L -3 ) • Minimum air required for combustion of coal :- WA • = 1 { (2.664 * TCF ) +( 7.937 * H2F ) + ( 0.996 * SF ) – O2F } • 23.2 • = WA Kg / Kg of Coal • = 6.04 Kg / Kg of Coal (for designed Coal) Excess air = 21 Where, O2 is Oxygen percent in flue gas at AH exit– 6 % 21 – O2 = E A % ( 1.40 ) Total Combustion air = Minimum air * Excess air = WA * EA = 6.04 * 1.40 = 8.45 Kg / Kg of Coal
- 20. KHAPERKHEDA THERMAL POWER STATION Total moisture in air = ( Sp. Humidity of air Kg / Kg ) * ( Total Comb. air Kg / Kg ) = 0.025 * 8.45 TMA = 0.21 Kg / Kg of air Note : Sp. Humidity of air ( 0.025) is to be taken from psychometric chart depending upon dry bulb temp ( 38 o C ) & wet bulb temp (30.5 o C ) Loss L–3 = TMA * 1.88 * ( Tgo – Tamb ) * 100 4.1868 * CV of Coal = 0.21 % ( design) (5) Dry Gas loss :- ( L – 4 ) Wdg , Weight of dry gas = { TCF + ( SF/2.67) } – ( 100 * u ) 12 * CO2 (APH Outlet) = Wdg Kg / Kg of coal Sensible heat of Wt. of dry gas in Sp. heat of gas Tgo – Tamb dry gas ( SH ) = kg / Kg of Coal * in KJ / Kg / o C * SH = Wdg * 30.6 * (Tog – Tamb ) KJ / Kg. Loss ( L– 4 ) = Sensible heat of gas * 100 4.1868 * CV of Coal = SH * 100 4.1868 * CVCF = 4.24 % ( Design )
- 21. KHAPERKHEDA THERMAL POWER STATION (6) Loss due of radiation : ( L – 5 ) Boiler Load = { 72.80 – 0.14522 * ( 502.70 – TSF ) } = LB % Radiation Loss = { 0.25 – 0.0018382 ( LB – 72.80 )} L – 5 = 0.21 % ( design ) (7) Unaccounted Loss = ( L– 6 ) = 1.50 % This Loss is assumed to be constant at all loads. Total losses : ( TL ) 1> Loss due to unburnt carbon , L – 1, - 2.00 % 2> Loss due to moisture + H2 in fuel, L – 2, - 5.23 % 3> Loss due to moisture in air, L – 3, - 0.21 % 4> Dry gas loss, L – 4, - 4.24 % 5> Radiation loss, L – 5, - 0.21 % 6> Unaccounted losses, L – 6, - 1.50 % TL - 13.39 % Boiler Efficiency = 100 – Total losses = 100 – 13.39 % EB = 86.61 %
- 22. KHAPERKHEDA THERMAL POWER STATION Designed Boiler efficiency = 86.61 % at 210 Mw (NCR) Overall Heat Rate = T / G heat Rate *100 = 1970 * 100 = 2275 Kcal/Kwh Blr. Effy. 86.61 (1 KW = 860 KCAL) Overall Efficiency = 860 * 100 = 860 * 100 = 37.80 % overall HR 2275
- 23. KHAPERKHEDA THERMAL POWER STATION Dry Gas % 4.37 4.34 3.84 H2O & H2 in Fuel % 5.25 5.24 5.21 H2O in Air % 0.21 0.21 0.19 Unburnt Carbon % 2 2 2 Radiation % 0.2 0.21 0.32 Unaccounted % 1.5 1.5 1.5 Manufacturer's Margin % 1.5 1.5 1.5 Total Losses % 13.53 13.5 13.06 Efficiency % 86.47 86.5 86.94 Fixed Carbon % 35 Volatile Matter % 26 Moisture % 10 Ash % 29 Sulphur % 0.6 Grindability Index HGI 50 Higher Heating Value Kcal/kg 4400 Size of Coal to Mill mm 25 Description Unit HP Heaters In Service BMRC 210 MW 168 MW PREDICTED BOILER LOSSES : - DESIGNED COAL PARAMETERS : -
- 24. KHAPERKHEDA THERMAL POWER STATION SAMPLE M% MM % C% H% N% S% O% UNIT#1 7.4 44.5 38.37 3.3 0.75 0.45 5.23 UNIT#2 6.9 46.5 37.8 3.32 0.73 0.40 4.35 UNIT#3 7.3 45.3 38.32 3.09 0.71 0.39 4.89 UNIT#4 6.9 46.2 38.02 2.99 0.69 0.55 4.69 AVG 7.13 45.6 3 38.1 2 3.18 0.72 0.44 4.78 ULTIMATE ANALYSIS BY MECL :
- 25. KHAPERKHEDA THERMAL POWER STATION THANK YOU