Flue gas desulphurisation technics .ppt
- 1. Final Audit :Utilization of Flue Gas Energy P M V Subbarao Professor Mechanical Engineering Department Minimize Final Exhaust Gas Temperature…. Properly Utilize Enthalpy of Flue Gas….
- 2. s 1 2 3 4 5 6 2f 2s 4 5 2 3 h h m h h m m reheatstea f mainsteam
- 3. DPNL SH Platen SHTR R H T R LTSH Economiser APH ESP ID Fan drum Furnace BCW pump Bottom ash stack screen tubes Thermal Structure of A Boiler Furnace
- 4. Furnace ater wall absorption Platen SH Pendent SH CSH Reheater Combustion Losses C & R losses Hot Exhaust Gas losses
- 5. Sequence of Energy Exchange from Flue Gas to Steam PLATEN SH FLUE GAS EVAPORATOR Water Wall COVECTIVE LTSH RH PENDENT SH
- 6. Fuel Power Furnace absorption Platen SH Final SH LTSH Reheater Combustion Losses C & R losses Hot Exhaust Gas losses ~4000C
- 7. Details of 500 MW(e) Capacity Indian Power Unit • Main steam Flow rate: 425 kg/s. • Main Steam Temperature: 5400C • Reheat Steam Flow rate: 38.7 kg/s. • Air Flow Rate: 577.06 kg/s. • Coal Flow Rate: 73.8 Kg/s.
- 8. 500 MW
- 9. Gas Temperatures • Platen Super Heater: • Inlet Temperature: 1236.4 0C • Outlet Temperature: 1077 0C • Final Super Heater: • Inlet Temperature: 1077 0C • Outlet Temperature: 962.4 0C • Reheater: • Inlet Temperature: 962.4 0C • Outlet Temperature: 724.3 0C • Low Temperature Super Heater: • Inlet Temperature: 724.30C • Outlet Temperature: 481.3 0C Steam Temperatures • Platen Super Heater: • Inlet Temperature: 404 0C • Outlet Temperature: 475 0C • Final Super Heater: • Inlet Temperature: 475 0C • Outlet Temperature: 540 0C • Reheater: • Inlet Temperature: 345 0C • Outlet Temperature: 5400C • Low Temperature Super Heater: • Inlet Temperature: 3590C • Outlet Temperature: 404 0C
- 10. Design Calculated 1 Adiabatic Flame Temp (K) 1957 1966 2 FEGT (0C) 1102 1117 3 Platen SH-I Outlet (0C) 932 951 4 Platen SH-II Outlet-I outlet (0C) 859 878 5 RH 3rd & 2nd outlet (0C) 595 604 6 RH 1st Stage outlet (0C) 510 531 7 Economiser outlet (0C) 385 398 8 APH Outlet (0C) 138 151 Flue Gas Temperature At different regions of Furnace:210 MWe)
- 11. Steam and Gas Paths
- 12. Suggested Fluid Velocities • Flue gas velocities: 10 – 18 m/s. • Steam in super heaters & reheaters: 10 – 25 m/s. • Water Wall circulation : 0.35 – 3.5 m/s.
- 13. 500 MW
- 14. LMTD for various Devices
- 15. Surface Area of Heat Exchangers: 500 MW
- 16. Economizer • The economizer preheats the feed water by utilizing the residual heat of the flue gas. • It reduces the exhaust gas temperature and saves the fuel. • Modern power plants use steel-tube-type economizers. • Design Configuration: divided into several sections : 0.6 – 0.8 m gap
- 19. Thermal Structure of Economizer • Out side diameter : 25 – 38 mm. • Tube thinckness: 3 – 5 mm • Transverse spacing : 2.5 – 3.0 • Longitudinal spacing : 1.5 – 2.0 • The water flow velocity : 600 – 800 kg/m2 s • The waterside resistance should not exceed 5 – 8 %. Of drum pressure. • Flue gas velocity : 7 – 13 m/s.
- 20. Thermal Balance in Economizer. • The energy absorbed by steam • The convective heat lost by flue gas • Overall Coefficient of Heat Transfer, U ) ( , , , in eco out eco steam con abs h h m Q T UA Q eco loss con ,
- 21. Mean Temperature Difference • The average temperature difference for parallel flow and counter flow is expressed as • It is also called log mean temperature difference • When tmax / tmin > 1.7, the average temperature may be expressed as: • Generally, the flow direction of the flue gas is perpendicular to the axes of tubes. • If number of bends are more than four, the flow can be treated as counter or parallel flow. min max min max log 3 . 2 t t t t t 2 min max t t t
- 22. Complex Flow • Parallel flow and counter flow may simultaneously exist in one section of an economizer. • This is called complex flow.
- 23. • For a given set of inlet and outlet temperatures of the fluids, • The temperature difference of parallel flow is the greatest, • The temperature difference of counter flow is the lowest • And that of complex flow is in between. • The average temperature difference in a complex flow can be calculated as: • When • Otherwise, the temperature difference is determined by • The value of Ktd is determined by flow type and the thermal parameters. co pa t t t 5 . 0 co pa t t 92 . 0 co td t K t
- 26. Gas Temperatures • Platen Super Heater: • Inlet Temperature: 1236.4 0C • Outlet Temperature: 1077 0C • Final Super Heater: • Inlet Temperature: 1077 0C • Outlet Temperature: 962.4 0C • Reheater: • Inlet Temperature: 962.4 0C • Outlet Temperature: 724.3 0C • Low Temperature Super Heater: • Inlet Temperature: 724.30C • Outlet Temperature: 481.3 0C • Economizer: • Inlet Temperature: 481.3 0C • Outlet Temperature: 328.5 0C Steam Temperatures • Platen Super Heater: • Inlet Temperature: 404 0C • Outlet Temperature: 475 0C • Final Super Heater: • Inlet Temperature: 475 0C • Outlet Temperature: 540 0C • Reheater: • Inlet Temperature: 345 0C • Outlet Temperature: 5400C • Low Temperature Super Heater: • Inlet Temperature: 3590C • Outlet Temperature: 404 0C • Economizer: • Inlet Temperature: 254 0C • Outlet Temperature: 302 0C
- 27. Furnace absorption Platen SH Pendent SH CSH Reheater Economizer APH Combustion Losses C & R losses Hot Exhaust Gas losses