Steam Power Plant

A brief explanation of how steam power plant works and what are the main factors effecting it. I also include figure and video which will help you better understand this process.

1. Steam Power Plant Thermal Energy Converted into Electrical Power

2. Table of Contents Basics Arrangements Cooling Location Efficiency

3. Basic Definition, Advantages & Disadvantages Steam power plant converts heat energy into electrical energy. The Rankine cycle is the fundamental operating cycle of all power plants where an operating fluid is continuously evaporated and condensed. We use different type of fuels such as Coal, Natural Gas etc. The typical life is 30 to 40 years.

4. Basic Definition, Advantages & Disadvantages Rankine Cycle: It is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work while undergoing phase change. The heat is supplied externally to a closed loop, which usually uses water as the working fluid.

5. Basic Definition, Advantages & Disadvantages Advantages Cheap coal is used Can be installed anywhere near fuel & water supply Requires less construction space Cost of generation is less Disadvantages Air pollution from smoke fumes Costs more to run compared with other types of power station

6. Arrangements Components that make up a steam power station Cooling tower Cooling water pump Pylon (termination tower Unit transformer Generator Low pressure turbine Boiled feed pump Condensor Intermediate pressure turbine Steam governor High pressure turbine Deaerator Feed heater Coal conveyor Coal hopper Pulverised fuel mill Boiler drum Ash hopper Super heater Forced Draught fan Reheater Air Intake Economiser Air preheater Precipitator Induced draught fan Chimmney stack

7. This schematic diagram must be properly understood. it is the basis upon which Steam power station designs are done. the individual power station complexity may differ slightly to the schematic and yet over and above that will use the same principle .

8. Arrangements Components that make up a steam power station Stage 1: Coal & Ash handling This stage is seen as the entrance and exit of fuel (coal) used . The initial handling treatment and storage of coal and the final handling and disposal of Ash . *Coal conveyor (14 ) * Coal hopper (15 ) * Pulverizer Mill (16 ) * Ash hopper (18)

9. Arrangements Components that make up a steam power station Stage 2: Steam Generating Plant This stage is seen as the energy loss stage. The steam creation by heat accounts for the greater percentage of power station in-efficiency . *Boiler drum (17 ) * Superheater (19 ) * Reheater (21 ) * Economizer (23 ) * Preheater(24 ) * Forced d-fan(20 ) * Induced d-fan(26 ) * Chimney(27)

10. Arrangements Components that make up a steam power station Stage 3 & 4: Steam Turbine & Alternator/Generator This stage is seen as the energy conversion stage. The steam turbine converts steam energy to rotational mechanical energy, while the Alternator/Generator converts rotational mechanical energy into electrical energy . *Pressure turbines (6; 9 & 11 ) * Steam governor (10 ) * Boiler feed pump (7) *Generator (5) * Transformer (4) * Pylon (3)

11. Arrangements Components that make up a steam power station Stage 5 : Feed Water & Cooling This stage is seen as the recycling stage. Steam used in boiler chamber is condensed back to water for re-use . *Cooling tower (1) * Water pump (2) * Condenser (8 ) * Precipitator (25)

12. Cooling Wet cooling method The condenser itself uses cold water and employs the principle of heat exchange. As the cool water is returned to the boiler, the hot water in the condenser is pumped to the cooling tower. Here water is sprayed and thus falls down to the water pond under the cooling tower. As the water falls it is cooled by the natural cold air. The cooled water is pumped back to the condenser, and the cycle is repeated. This method uses a lot of water through evaporation. Water Consumption ≈ 2.5 lt /kWh

13. Cooling Dry cooling method In this method steam is circulated inside a radiator-like heat exchanger and is cooled by the natural cold air blown (naturally or using draught fans) between pipes of the heat exchanger. The cooled/condensed steam is returned to the boiler( Rankine cycyle ). This method greatly decreases water wastages through evaporation by almost 84% of the wet cooling method. It is called Direct dry cooling since the condenser has been eliminated completely. This method is favored where water is scarce. Water Consumption ≈ 0.4 lt /kWh

14. Cooling Wet cooled condenser Here the condenser is still used to cool steam that is pumped back to the boiler. The hot water from the condenser is then pumped to Heat exchangers in the cooling tower and natural ventilation is used to cool the water which can then be pumped back to the condenser. Notice that water consumption here is double that consumed in the direct dry cooling method. Water Consumption ≈ 0.8 lt /kWh

15. Cooling Jet cooled condenser Here the exhaust steam leaving the low-pressure turbine condensed by a jet spray of cold water. the resulting hot water collected is through heat exchangers in the cooling tower. The cooled water is sent back to the boiler. Notice that water consumption is equal to the previous cooling method. Water Consumption ≈ 0.8 lt /kWh

16. Location Factors influencing selection of construction site. Supply of fuel : The station must be located close to coal mines to reduce transportation cost of fuel . Availability of water : The station must be located near a river bank or canal for continuous water supply . 3. Transportation facilities : The station must be well connected to major transport routes eg Rail or Road.

17. Location Factors influencing selection of construction site. 4. Cost & type of land: The land must have a good bearing capacity for heavy equipment and yet be cheap enough to purchase. Distance from populated areas: The station must be located as far away from populated areas as possible due to air pollution. 6 . Nearness to load centers: In order to reduce the transmission cost the plant should be located near load centers.

18. Efficiency How efficient this power station is. This type of power station has very high energy losses due to great heat loss in the boiler and condenser. the following equation is used to calculate power station efficiency: The above generally works out to ±30% for steam power stations.

19. Efficiency How efficient this power station is. We can further calculate overall efficiency as follows : The above generally works out to ±29% ( 1% loss at the generator ) for steam power stations.

20. Thank you Any Question?

21. References V.K Mehta & Rohit Mehta :- Principles of Power systems (1st ed.). S.CHAND https://en.wikipedia.org/wiki/Thermal_power_station