Steam turbine power plant

Steam turbine power plant

1. STEAM TURBINE POWER PLANT Co u rse I nstructor: Md. Tarek Ur Rahman Erin Sr. Lecturer, MTE, WUB Course Title: Power Plant Engineering; Course Code : MTE 905 WEEK 04

2. Overview of topics Steam power plant Major Components of steam power plant Boiler Boiler Mountings Air Pre heater Super-heater Economizer Re heater Turbine Condenser Feed water pump

3. Elements of a simple steam power plant

4. Steam power plant A steam power plant i s a p o wer pl a nt in which h e a t e d , wat e r is t u rns i n to steam and spins a steam turbine which drives an electrical g e n e ra t or to produce electricity. Fig: Layout of steam power plant.

5. Major Components of steam power plant

6. Boiler A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications . Two types, Water tube boiler Fire tube boiler

7. Water tube boiler The water flow through the tube and the flow gases flow outside the tube.

8. Fire tube boiler The fire tube boiler i n which the flow gases passes through the tubes and water stor e out side the tube.

9. Boiler Accessories Air Pre heater Air pre heater is a heat recovery unit . An air pre heater is used to recover the heat from the exhaust flue gas.

10. Boiler Accessories Air Pre heater The purpose of the air pre heater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas. Fig: Layout of air pre heater. There are two types of air pre heaters for use in steam generators Tubular type built into the boiler flue gas ducting Regenerative air pre heater

11. Boiler Accessories Super - heater A super- heater is a device used to convert saturated steam or wet steam into dry steam used in steam engines

12. Boiler Accessories Super heater It’s purpose is to increase the temperature of steam without raising the pressure. It’s generally an integral part of the boiler Type of Super heater A radiant super heater is placed directly in the combustion chamber. A convection super heater is located in the path of the hot gases. A separately fired super heater, as its name implies, is totally separated from the boiler.

13. Boiler Accessories Economizer An economizer is a device used to heat the feed water and heat the condensate from turbines before it is pumped to the boilers by utilizing the heat exhaust lea v ing f lue gasses through in the before ch i m ne y . Fig: Layout of Economizer.

14. Boiler Accessories Econom i zer Economizers are commonly used as part of a heat recovery steam generator in a combined cycle power plant. A common application of economizers in steam power plants is to capture the waste heat from boiler stack gases (flue gas) and transfer it to the boiler feed water. This raises the temperature of the boiler feed water

15. Boiler Accessories Re-heater

16. Boiler Accessories Re-heater Re-heaters are the same as the super-heaters but the temperature of it’s a little bite less than super-heaters and their pressure is 20%- 25% less than the super-heater, It usually use to elevate the steam temperature. After expanding through the high pressure turbine the exhaust steam is returned to the boiler at 360 C and 42 bar pressure for reheating before being used in the intermediate pressure turbine. The re-heater reheats the steam from a temperature of 360 C back to 568 C.

17. Boiler Mountings Different fittings and devices necessary for the operation and safety of a boiler are called boiler mountings. The various boiler mountings are: Water level indicator Pressure gauge Steam stop valve Feed check valve Blow-down cock Fusible plug Safety valve : spring loaded, dead weight, lever type.

18. Boiler Mountings Water level indicator The function of the water level indicator is to indicate the level of water in the boiler constantly. Every boiler is normally fitted with two water level indicators.

19. Boiler Mountings Pressure gauge The pressure gauge is used to indicate the steam pressure of the boiler. The gauge is normally mounted in the front top of the steam drum . Pressure gauges are connected to the steam space of the boiler and usually have a ring type siphon tube which fills with condensed steam and protects the dial mechanism from high temperatures . The commonly used pressure gauge is the Bourdon type pressure gauge .

20. Boiler Mountings Steam Stop Valve The function of the stop valve is to regulate the flow of steam from the boiler to the prime mover as per requirement and shut off the steam flow when not required. A commonly used steam stop valve is shown in figure, it consists of main body, valve, valve seat, but and spindle, which passes through a gland to prevent leakage of steam. The spindle is rotated by means of a hand wheel to close or open.

21. Feed Check Valve Boiler Mountings The function of the feed check valve is to allow the supply of water to the boiler at high pressure continuously and to prevent the back flow of water from the boiler when the pump pressure is less than boiler pressure.

22. Boiler Mountings Blow-Down Cock The function of blow-down cock is to remove sludge or sediments collected at the bottom-most point in the water space in a boiler, while the boiler is steaming.

23. Boiler Mountings Safety Valves The function of a safety valve is to prevent the steam pressure in the boiler exceeding the desired rated pressure by automatically opening and discharging steam to atmosphere allowable pressure falls back to normal rated value. There are three types of safety valves, Spring loaded (Rams bottom) type, Dead weight type, and Lever type.

24. Turbine A turbine is a type of engine that can extract energy from a fluid, such as water, steam, air, or combustion gases. It can be contrasted with a piston engine which uses a piston instead of a turbine to extract energy. Steam turbine Water turbine Wind turbine Gas turbine A rotor of a modern steam turbine, used in a power plant

25. Turbine Steam Turbine A s team t u rbine i s a prime mover in which rotary obtained gr a dual ch a nge m o t ion is by the of momentum o f t he s tea m . In a s te a m turbine the force exerted on the blades is due to the velocity of steam.

26. Turbine Types of steam turbine Impulse turbine Reaction turbine

27. Turbine Impulse turbine A tur b ine that is dri v en by high velocity jets of water or f r o m a n o z z le on to vanes or att a c h ed to a steam dire c ted buckets wheel. The re s ulti n g impulse (as described by Newton's second law of motion) spins the turbine and removes kinetic energy from the fluid flow.

28. Impulse turbine In impulse turbine, the drop in pressure of steam takes place in a stationary nozzle. The drop in pressure leads to conversion of enthalpy into kinetic energy of a fluid. Hence t h e v elocity of t h e f l uid incr e ase at t h e e x pe n se of temperature and pressure. This high velocity fluid (Jet) is deflected by a curved blade. A change in direction of a jet generates change in momentum of the fluid. A rate of c h ange i n m o men t um will genera t e a f orce on t he blade. A moti v e p o wer i s gene r ated, wh e n t his f o r ce can move t h e blade. Turbine

29. Turbine Reaction turbine A turbine in wh i ch the w o r k ing flu i d is accelerated by expansion in both the static nozzles and the rotor blades. Torque is produced by the momentum changes in the rotor and by reaction from fluid accelerating out of the rotor

30. Reaction Turbine: In a Reaction Turbine drop in pressure occurs in a movable nozzle . The drop in pressure leads to conversion of enthalpy into kinetic energy of a fluid. Hence t h e velocity of t h e fluid inc re a s e at t h e expe n se of temperature and pressure. A high velocity jet leaving the moving nozzle will generate a reaction on the nozzle. A motive Power is generated, when this reaction can move the nozzle. Turbine

31. Steam Turbine Cycle Thermodynamics Cycles Gas Cycles Vapour Cycles Working Fluid remains in Gaseous Phase throughout the Cycle. Working Fluid exists in Vapor Phase during part of the Cycle, and in liquid phase during remaining pa r t .

32. RANKINE CYCLE: THE IDEAL CYCLE FOR VAPOR POWER CYCLES Thr Rankine cycle , which is the ideal cycle for vapor power plants. The ideal Rankine cycle does not involve any internal irreversibilities. The simple ideal Rankine cycle

33. THE IDEAL REHEAT RANKINE CYCLE How can we take advantage of the increased efficiencies at higher boiler pressures without facing the problem of excessive moisture at the final stages of the turbine? Superheat the steam to very high temperatures. It is limited metallurgically. Expand the steam in the turbine in two stages, and reheat it in between ( reheat ) The ideal reheat Rankine cycle.

34. Conde n ser A condenser is designed to transfer heat from a working fluid (e.g. water in a steam power plant) to a secondary fluid or the surrounding air. The condenser relies on the efficient heat transfer that occurs during phase changes, in this case during the condensation of a vapor into a liquid.

35. Feed water pump A boiler feed water pump is a specific type of pump used to pump feed water into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are normally high pressure units that take suction from a condensate return system.

36. Feed water pump

37. Feed water pump Classification of pump There are two types of pump mainly used in steam power plant: Centrifugal pump Reciprocating pump

38. Thank You