Radiation Loss Steam Output

Heat Input is Pulverised Coal, Heat Output is Superheated Steam

Efficiency Calculations:

Standard Applied :- ASME Standard PTC 4.1

Calculation Method :- Loss Method

Losses calculated as percentage of INPUT as 100%

1) Loss due to dry flue gas = 4.928%

2) Loss due to Unburnt Carbon = 0.331%

3) Due to Sen. Heat of Bottom Ash = 0.071%

4) Due to Sen. Heat of Fly Ash = 0.102%

5) Radiation Losses = 0.200%

6) Loss due to moisture in Fuel = 1.263%

7) Loss due to Hydrogen in Fuel = 5.537%

8) Loss due to Moisture in Air = 0.074%

9) Unaccounted Losses = 1.327%

Total Losses = 13.83%

CONTROLLABLE LOSSES 1:

1. LOSS DUE TO DRY FLUE GAS : CONTROLLED BY PROPER CLEANING OF THE FURNACE

2. LOSS DUE TO UNBURNT IN BOTTOM ASH : CHECK THE FINENESS OF PULVERISED COAL. CHECK THE % RETENTION ON 50 MESH. IT SHALL NOT EXCEED 1%.

3. LOSS DUE TO UNBURNT IN FLY ASH : IF UNBURNT IN FLY ASH EXCEEDS 0.8% IT INDICATES INCOMPLETE COMBUSTION DUE TO LESS AMOUNT OF AIR. CHECK FOR O2 % AT THE APH FG INLET FOR 2.8%, INCREASE IF NECESSORY TO 3.2%. AGAIN CHECK FOR UNBURNTS IN FLY ASH. SIMULTANIOUSLY CHECK FOR AIR LEAKAGES/INGRESS IN THE SECOND PASS.

4. GCV Calculations for Coal : 1) Useful Heat Value = 8900 – 138(A%+M%) kcal/kg2) Gross Calorific Value (Air Dry Basis) = (UHV + 3645 – 75.4 M%)/1.466 kcal/kg

3) Ash % (As fired basis) = [A %] (100 - TM%)/(100 – M%) %4) Gross Calorific Value (As fired Basis) = [GCVAD] (100 - TM%)/(100 – M%) kcal/kg5) Net Calorific Value =[GCV] – 10.02M% Kcal/kg

Heaters:For 0.56C increase in TTD on Top/other heaters, 0.016/0.013% increase in HR.For 0.56C increase in DCA 0.005% increase in HR.PURPOSE OF FEED WATER HEATERS:1. They provide efficiency gains in the steam cycle by increasing the initial water temperature

to the boiler, so there is less sensible heat addition which must occur in the boiler.2. They provide efficiency gains by reducing the heat rejected in the condenser, and they

minimize the thermal effects in the boiler.

C) Pump Performance Assessmenti. Hydraulic PowerHydraulic power of a pump is gives by:Ph(kW)= QX (hd-hs) XρX g/1000Q= Volume Flow rate (m3/s)ρ=Density of fluid(kg/m3)g= Acceleration due to gravity (m/s2)(hd-hs)= Total Head in metersii. Motor Input PowerInput Power can be calculated using Power Analyzer.iii. Pump Shaft PowerIt is calculated by multiplying the motor input power by motorefficiency.Ps= Pm X ɳmotor

ɳmotor=Synchronous speedXRated SpeedX100/Synchronous Speediv. Pump EfficiencyIt is calculated by dividing the hydraulic power by pump shaftpower.ɳpump= Ph/Ps[11]v. Specific Energy Consumption(SEC)

SEC= Pm/Q

Reliance Page : 40,43,44.

22 Tips - How to reduce Auxiliary Power Consumption of 500/600/660/800 MW Sets ?

Auxiliary Power Consumption (electrical energy needed to run the Unit at variable loads)

1.    Conduct Energy Audit of the Units/Plant every year by an efficient Energy Auditor

2.    Implement all the recommendations of the said Energy Auditor for the Units/Plant

3.    Identify and plug all energy loss points of the Units/Plant to the extent possible

4.    Improve Unit overall efficiency (36% for sub-critical & 42% for super-critical)

5.    Improve Unit Heat Rate (close to 2300/2000 kCal/kWh for sub-critical/super-critical)

6.    Maintain Unit PLF close to 90% (for 330 days in a year/nearly 8000 running hours)

7.  Reduce Specific Coal Consumption (0.5 - 0.6 kg/kWh) by sustained optimization of combustion in the boiler using suitably blended coal (60% ‘F’ Grade + 40% ‘D’ Grade)

8.   Reduce Specific Oil Consumption in the steaming Boiler (close to 1.0 ml/kWh)

9.   Reduce DM Make-up Water Consumption in the steaming Boiler (close to 1.0%)

10. Carry out routine/preventive/annual/capital maintenance of all load bearing equipments including their prime movers of the Unit as per recommendations of respective OEMs 

11. Maintain desired voltage/frequency level for the auxiliaries when the Unit is in Bus

12. Keep Unit Transformers in service when the Unit is in Bus beyond 10% rated load 

 

13. Use combination of Steam Turbine Driven (2x50% running at 100% rated load) & Electric Motor Driven (1x50% kept as standby) Boiler Feed Pumps for running Unit

14. Or use Motor Driven Boiler Feed Pumps with Multi-Stage Variable Speed Drive (with planetary gears) Vorecon (3 x 50% E-motor + Vorecon) for running Unit

15. Use VFD for the prime movers of all other load bearing equipmentsfor the running Unit

16. Keep all standby load bearing equipments of the Unit in switched off/standby mode 

17. Maintain desired Condenser Vacuum (around 76 - 80 mm of Hg) inthe running Unit

18. Maintain optimum back end temperature (around 1300C - 1400C) in the steaming boiler

19. Maintain unburnt carbon in fly/bottom ash of the steaming boiler on lower side (~1%)

20. Run the Unit at Base Load (100% Rated Load) on 24x7 basis

21. Maintain ash evacuation/disposal of the steaming boiler in dry mode except exigency

22. Maintain optimum illumination level in the Plant (use energy efficient lamps)