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STRATEGIES FOR EFFICIENT OPERATION

STRATEGIES FOR EFFICIENT OPERATION. Author:- D.N.Patel, DGM (Head-Operation), TRN Energy Private limited, Nawapara (Tenda), Raigarh (C.G) 2X300 MW Coal Based Thermal Power Plant

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STRATEGIES FOR EFFICIENT OPERATION

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  1. STRATEGIES FOR EFFICIENT OPERATION Author:- D.N.Patel, DGM (Head-Operation), TRN Energy Private limited, Nawapara (Tenda), Raigarh (C.G) 2X300 MW Coal Based Thermal Power Plant Boiler Make: - China Western Power Company, China Turbine& Generator Make:- M/s. Beijing Beizhong, China.

  2. INTRODUCTION Power is the essential for the economic development of a country. As the economy grows, the need for more and more power is self-justified. New power installations are capital intensive, and hence, there is urgent need for optimal utilization of existing capacities by efficiently running of thermal power stations and saving energy used as fuel (Coal and Oil) and auxiliary power consumption by reduction of Net Heat Rate. Honorable Prime Minister Shri Narendra Modi Says that:- My vision for India’s energy future has four pillars:- • Energy Access. • Energy Efficiency. • Energy Sustainability. • Energy Security.

  3. NEED FOR EFFICIENT OPERATION • As we know that at present all Indian thermal power stations are running at partial load either due to fuel (Coal/ Lignite) shortage or due to low demand at off peak hours. • We know that our plant efficiency decreases on part load operation, resulting higher heat rate and auxiliary power consumption. • We have to also save our environment by emitting lesser greenhouse gases to reduce global warming effect. (CO2, CO,SOX and NOX Emission). Hence, it is challenging to all of us to run the plant efficiently to decrease Heat rate, Aux Power consumption and Water consumption, also we need to meet Environment norms set up by the Central Pollution control Board to protect our Environment .

  4. NEED FOR EFFICIENT OPERATION • To save nation from global warming:-As our power demand is increasing day by day and our reserve coal stock is only for around 100 years, to save the fuel for future need, we must operate the plant efficiently. Increase in Efficiency means decrease of coal consumption and thereby reduced SOX, CO, CO2 emission and lesser impact in global warming.

  5. HOW TO INCREASE EFFICENCY For, Thermal Power Plant cycle efficiency is formulated as:- Efficiency=Power Generated in Kwh*860*100/ Heat Input in Kcal. Gross Unit Heat Rate=Heat input in Kcal/ Power Generated in Kwh. OR Gross Turbine Cycle Heat Rate/ Boiler Efficiency Turbine Cycle Efficiency=( 860/Turbine Cycle Heat Rate)*100. Gross Cycle Efficiency=(860/Gross Unit Heat Rate)*100 (860 is Heat Energy in Kcal Equivalent to 1 KWh Electrical Energy)

  6. HEAT RATE CONCEPT • Goss Heat rate=Heat input/ Electrical Power at Generator output. • Net Heat Rate= Heat input / Electrical Power at Switchyard Output (Ex-Bus Power). Heat rate is the Heat Energy required to generate 1Kwh Electrical Energy. • Which is given as:- • Gross Unit Heat Rate= Turbine Cycle Heat Rate/ Boiler Efficiency • Gross Unit Heat rate= {Coal Consumption (In MT)* Feed Coal GCV (Kcal/Kg)+ Secondary Fuel consumption* Secondary Fuel GCV } / Electrical Energy Generated in MWh. • Gross Heat rate= Specific Coal consumption ( kg/Kwh)*Feed Coal GCV( Kcal/Kg) • To reduce, the Heat rate either we have to focus on decreasing turbine Cycle Heat rate or increase the Boiler Efficiency (Decrease the Boiler Losses). • Net Heat rate=Gross Heat rate/ (1-APC %). Reduction of Heat rate by 1 Kcal/Kwh cost implication = Suppose feed coal GCV is 3200 Kcal/Kg Landing Cost of Coal =Rs.2500/-per MT Heat Rate =2350 Kcal/Kwh Annual PLF=85% of 2*300 MW Thermal Power station Coal Saving due to reduction of Heat rate-1 Kcal/Kwh=(1/3200)*0.85*365*600*24=1396 MT. Cost Implication=1396*2500= Rs. 3,490,000/- Per Year.

  7. STRATEGIES FOR EFFICIENT OPERATION We have following actions to be taken for Efficient Operation of the Thermal Power Plants:- • Improving (Reduction of) Turbine Cycle Heat Rate • Increasing Boiler Efficiency • Reduction of Aux Power Consumption. • Reduction of startup oil consumption.

  8. IMPROVING (REDUCTION OF) TURBINE CYCLE HEAT RATE • TURBINE LOSSES:- • External Losses • Internal Losses. Turbine External Losses:- • Shaft gland leakage Losses. • Journal & thrust bearing losses. • Governor and oil pump losses. Turbine Internal Losses:- • Inter stage gland leakage losses. • Wetness losses. • Leaving Losses. • Exhaust Losses

  9. Strategies to increase Turbine Efficiency or improving Turbine Cycle Heat rate • To run the unit closes to design parameters. • Prefer sliding pressure operation during part load to avoid throttling losses. • Do regular condenser tube cleaning to improve condenser vacuum. • Ensure timely calibration of transmitters, gauges and RTDs. • To Evaluate HPH, Condenser and Cooling Tower Performance time to time. • Regular fins cleaning of cooling Tower and changing of Blade angle as per ambient temperature and wet bulb temperature. • Maintain gland steam temperature and pressure as per design. • To get timely attending of any steam and water leakages. • Timely changeover of running equipment as per change over schedule for reliability. • Inspection of Turbine glands, Bearings and Internal parts during overhauling and corrective actions to be taken. • Timely attending of HP drain Valves passing and leakages.

  10. INCREASING BOILER EFFICIENCY • Boiler efficiency is a combined result of efficiencies of different components of a boiler. A boiler has many sub systems whose efficiency affects the overall boiler efficiency. Couple of efficiencies which finally decide the boiler efficiency is- • Combustion efficiency • Thermal efficiency • Apart from these efficiencies, there are some other losses which also play a role while deciding the boiler efficiency and hence need to be considered while calculating the boiler efficiency.

  11. BOILER LOSSES Following losses are considered in the analysis of the boiler performance:- • Dry flue gas losses • Moisture in fuel losses • Moisture in combustion air • Loss due to H2 in coal • Loss due to unburnt carbon • Unaccounted losses

  12. Strategies for increasing Boiler Efficiency or reducing Boiler Losses. • Maintain Boiler parameters close to design value. • Soot blowing of wall soot blowers, LRSB and APH should be carried out as per schedule or parameter deviation for optimum Heat Transfer. • Excess Air to be optimized around 18-22% to reduce dry flow gas losses and un-burnt losses. • Valve passing to be get attended timely. • Water Chemistry to be maintained as per design parameters to avoid CBD opening for silica control. • Re-Heater temperature control to be done thru burner tilting. • SADC Dampers passing mismatch to be get attended on opportunity. • Burner Nozzles to be get cleaned /rectified during Boiler shutdown. • Bottom de-ashing, Economizer de-ashing and fly gas evacuation to be carried out at proper interval. • Wind Box DP should be maintained as per Boiler load.

  13. REDUCTION OF AUXILIARY POWER CONSUMPTION Auxiliary Power is the power required to operate the plant auxiliaries of BTG, CHP, AHP, DM Plant and other utilities. Financial implication of the Auxiliary Power is as given:- • Saving of Auxiliary power can be exported to grid either as per PPA rate, Power Exchange rate or deviation rate for the particular block. • By reducing the auxiliary power, Electricity duty will be reduced at rate of Rs.0.65/kwh saving of Auxiliary Power. If we assume PPA/IEX/Deviation rate is: Rs3.00/Kwh then financial implication of Auxiliary Power shall be Rs.3+0.65=Rs.3.65/Kwh. If we save 1KW of Auxiliary then yearly cost saving will be; Rs.1*365*24*3.65=Rs.31974/-.

  14. STRATEGIES FOR REDUCTION OF AUXILIARY POWER CONSUMPTION • Optimization of Boiler Total air causing reduction of ID, FD and PA fan Current. • Sliding pressure operation helps to reduce BFP current. • CEP Recirculation valve to be kept in auto and it should be close or minimum opening during normal operation. • CW/Cooling Tower fans can be stopped during winter as per ambient temperature and design CW temperature. • Make up pumps can be stopped and prefer gravity make up wherever possible. • All leakages and valve passing to be get attended timely. • Daily evaluation of currents and power taken by auxiliaries. • Specific Power consumption of CHP, AHP, DM plant and BTG area to be monitored on monthly basis and find the scope for reduction of Auxiliary Power Consumption. • Avoid rewinding and prefer new energy efficient Motors. • Plant lighting to be replaced with LED. • For switching ON/OFF of lightings, timers to be installed. • A committee for APC Reduction to formed and offer suggestions by individuals. • Installation of VFDs. • Operation practices to reduce aux power during start up and shutdown. • Awareness among employees that “Saving of 1 unit Energy is equivalent of 2 unit generation”.

  15. REDUCTION OF START UP OIL CONSUMPTION STRATEGIES FOR REDUCTION OF STARTUP OIL CONSUMPTION • Cleaning of oil guns properly before Boiler light up. • Checking of oil guns before Boiler light up. • De-aerator pegging to increase water temperature before Boiler light up subjected to availability of auxiliary steam. • Boiler water draining and filling to achieve desired water quality. • Entire equipment ,valves, Gates ,dampers and protections checking before Boiler light up to avoid any delay reason during unit startup. • Condenser vacuum pulling (in case of cold start up) before fours Boiler light up to raise the Turbine casing /shaft temperatures and reducing soaking time of Turbine.

  16. TRN ENERGY PRIVATE LIMITED, RAIGARH Reduction of Auxiliary Power, LDO Consumption & Heat Rate By Operational Excellency

  17. ACTION TAKEN TO REDUCE APC IMPLEMENTATION OF ACTION PLAN -1:- • One LDO Pump 45KW has been stopped and only one pump is kept running for both Units since 14-08-2017 • Hot well make pump of both units kept stopped and make up is being done through Gravity from 23-08-2017( Each Units having 22KW Motor). • CT fans were being stopped at night hours and CT fans kept running as per requirement in winter from 01-Nov-2017 to 28-Feb-2018 . • CW Fore bay make up pump has been stopped and make up is being done through Gravity (Motor Rating-37 KW from 01/10/2017 )

  18. IMPLEMENTATION OF ACTION PLAN 1 & 2:- • PA Header pressure is being maintained according to coal flow to reduce the PA fan current from 01-10-2018.( Both PA Fan current reduced to 20 Amps • CT fans are being stopped at night hours and CT fans kept running as per requirement in winter from 01-Nov-2018 to 28-Feb-2019 . • Additional 10 KW power saving from 01-12-2018 due to running LDO pump change over from 55 KW to 45 KW . • Mill Seal Air fan current has been reduced to 150 Amps from 190 Amps by reducing its inlet damper and seal air to PA air DP optimized from 31/01/2019. • One Compressor (270KW) has been stopped from 14/02/2019 after attending air leakages.

  19. APC COMPARISION SHEET BEFORE AND AFTER IMPLEMENTATION OF ACTION PLAN • Remarks : - • APC percentage depends on specific coal consumption (SCC) as number of mills in service and total air flow increases on increasing of SCC. • From June 2018 to September 2018 (rainy season) moisture in coal increases hence we need more primary air for drying out moisture from coal so PA Fan, FD Fan & ID Fan loading Increases(SCC highlighted in yellow color). • In Rainy season due to increase in Relative humidity the number of CT fan in service increases to maintain condenser inlet temperature. • Station APC increased by approx. 0.3-0.5% if one unit was shutdown and only unit was running ,i.e. for the month Feb,April,May,June,July, August, September and January-2019.(highlighted in light green color)

  20. APC SAVING ACTION TAKEN AND ITS FINANCIAL IMPLICATIONS Note : 1. Total cost saving includes direct power saving that would have been sold either on LTA Or IEX and the saving in electricity duty imposed by the CSPDCL 2. Direct APC saving considered @ 3.00 Rs/KWh and saving in electricity duty considered @ 0.62 Rs/KWh. 3. All Calculation done from the date of Implementation to 31-03-2019 ,in case of CT Fans it was taken from 01-11-2018 to 28-02-2019.

  21. Action taken for Reduction of LDO Consumption • LDO pressure is reduced from 15 - 18 kg/CM2 to 08 - 10 kg/CM2. • Mill Total air gates, Hot air gates and Dampers are checked properly before Boiler Light up. • Drum silica is reduced during start up :- after 5 Kg/CM2 we open Boiler ring Header drains till 30 Kg/CM2. CBD is opened 100% after 5 Kg/Cm2 Drum pressure. • Deareator pegging steam charged before 4 Hrs. of Boiler light up to raise the water temperature (In cold startup). • Condenser vacuum pulling started before 4 Hrs. Boiler light up to increase turbine casing temperature (In cold startup). Continue……

  22. Continue…… • One Mill & Coal Feeder (Preferably Mill A in cold start up) is taken in service with minimum feeding after 50-60% HP/LP Bypass opening and Flue gas temp > 400°C at furnace exit. • Second Mill & Feeder (Preferably Coal Mill - B) is taken during Turbine Soaking . • After 60% load (180 MW), all oil guns are removed. • LDO consumption in Start up & Shut Down has been reduced drastically by our best operation practices from September 2017. Continue……

  23. REDUCTION OF LDO CONSUMPTION FOR DIFFERENT START UP • For Cold start up - 150 - 180 KL to 60 - 70 KL • For Warm Start up - 90 - 100 KL to 30 - 40 KL • For Hot Start up - 30 - 40 KL to 20 - 30 KL • For Shutdown - 15 - 20 KL to 03 - 08 KL

  24. SUMMARY OF COST SAVING ON REDUCTION OF START UP LDO CONS.

  25. REDUCTION OF HEAT RATE AND ITS FINANCIAL IMPLICATIONS • Heat rate has been reduced by 98.41 Kcal/Kwh due to our operation strategies for Heat Rate Reduction even after feed coal GCV is less( 3018 Kcal/Kg) than feed coal GCV of last financial year( 3142 Kcal/kg) . • To improve load factor of the unit. • To avoid high drain valve passing, manual isolation valves are kept closed. • Optimization of soot blowing for proper heat Transfer. • Optimization of Total air flow and excess air for proper combustion.

  26. HEAT RATE DATA COMPARISION SHEET FROM FY 2017-18 TO FY 2018-19

  27. SUMMARY OF TOTAL COST SAVING BY OPERATIONAL EXCELLENCY Total cost saved by operational excellency : RUPEES THIRTY THREE CRORE Other non –monetary benefits achieved by Operational Excellency :- 1. Avoid frequent tripping of Units. 2. Close to CERC Norms for Heat rate & Auxiliary Power Consumption. 3. Meet BEE Target of Net Heat rate for PAT Cycle-IV.

  28. THANK YOU

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