1. Name the four major circuits in steam power plant.

• Coal and ash circuit
• Air and flue gas circuit
• Feed water and steam circuit
• Cooling water circuit

2. What consists of air and flue gas circuit?

Air and flue gas circuit consists of forced draught fan, air pre heater, boiler, furnace, super heater, economiser, dust collector, induced draught fan and chimney.

3. What consists of feed water and steam flow circuit in steam power?

The feed water and steam flow circuit consists of feed pump, economiser boiler drum super heater, turbine and condenser.

4. What consists of cooling water circuit and coal & ash circuit in steam power plant?

The cooling water circuit consists of a pump, condenser and cooling tower. The coal and ash circuit consists of coal delivery, preparation of coal, handling of coal to the boiler furnace, ash handling and ash storage.

5. What is the main purpose of the reservoir?

The main purpose of reservoir is to store water received from catchments areas during the rainy seasons and supply the same during the dry season.

6. What is the main purpose of the dam?

The main purpose of the dam is to increase the height of water level and also to increase the working head of the hydraulic power plant.

7. Why trash rack is used?

The trash rack is used to prevent the entry of debris, which might damage the turbine runners and chock up the nozzle of impulse turbine.

8. What is the use of surge tank?

The surge tank is used to provide better regulation of water pressure in the system. The surge tank controls the water when the load on the turbine decreases and supplies water when the load on the turbine increases. Thus, surge tank controls the pressure variations resulting from the rapid changes in water flow in penstock and hence prevents water hammer.

9. What is the function of Fore bay?

Fore bay is considered as naturally provided surge tank. It is temporary water storage when the load on the plant is reduced and provides water for initial increment on increasing load.

10. Explain about penstock?

The pipe between surge tank and prime mover is known as penstock. It is designed to withstand high pressure. It is made up of reinforced concrete. In very cold areas, the penstock is buried to prevent ice formation and to reduce the expansion joints.

11. What is the use of spill Ways?

Spillway is like a safety valve of the dam. It discharges major flood without damaging the dam. It keeps the reservoir level below the maximum level allowed.

12. Write about prime movers?

Prime mover converts the kinetic energy of water into mechanical energy to produce electrical energy. Pelton wheel, turbine, Francis turbine, Kaplan turbine and Propeller turbine are prime movers used in hydraulic power plants.

13. What are the uses of air filter and superchargers in diesel engine power plant?

The purpose of air filter is to filter the air from dust and other suspended particles. The purpose of super charger is to increase the pressure of the engine to increase power of the engine.

14. What is the use of draft tube?

The draft tube is used to regain the kinetic energy of water coming out of reaction turbine. It enables the reaction turbine to be placed over tailrace level.

15. What is the function of cooling system in Diesel power plant?

The function of cooling system is to remove heat from the engine cylinder to keep the temperature of the cylinder in low range and extend engine life.

16. What consists of lubrication system in diesel engine power plant?

The lubrication system consists of oil pumps, oil tanks, filters, coolers and connecting pipes. The purpose of the lubrication is to reduce the friction of moving parts and also pipes to reduce the wear and tear of moving parts.

17. What is the purpose of intercooler in gas turbine power plant?

Since the power required to compress the air is less in isothermal process it is required to maintain the, temperature of air constant as far as possible. Hence the air leaving the L.P. compressor is cooled by intercooler and then passed to the H.P compressor.

18. Name two combined power cycles?

• Combined cycle of gas turbine and steam power plant.
• Combined cycle of gas turbine and diesel power plant.

19. Define turbo charging in combined gas turbine and diesel cycles?

In the combined cycle, the exhaust gas from the diesel engine is expanded in the turbine, which is coupled with compressor which supplies pressurized air to the diesel engine. This increases diesel engine output. This arrangement is known as turbo charging.

20. What is the main purpose of high-pressure boilers?

The high-pressure boilers are used to increase the efficiency of the plant and to reduce the cost of electricity production.

21. State important advantages of high-pressure boilers?

• The amount of scale formation is less, since the velocity of water through pipes are more.
• All parts of the system are heated uniformly, so there is no danger of overheating.

22. Name important high pressure boilers?

• La Mont boiler
• Benson boiler
• Loeffler boiler
• Velox boiler.

23. Write about La Mont boiler? What is the major disadvantage of La Mont boiler?

La Mont boiler is a forced circulation high pressure water tube boiler.

The major disadvantage is the formation of bubbles, salt and sediment on the inner surfaces of the heating surfaces. This reduces the heat flow and steam generation.

24. Write about Benson boiler? State some important advantages of Benson boiler?

Benson boiler is the high pressure, vertical fire tube boiler. This boiler has no drum and is ~designed to operate at critical pressure of 225 bar. Benson boiler has no drum. So the total weight of the Benson boiler is reduced by 20%, when compared to other boilers. The erection of Benson boiler is easier and quicker.

25. Write about Loeffler boiler?

The major disadvantage in La Mont boiler is the deposition of salt and sediment on the inner surface of the water tubes. It reduces the heat transfer and ultimately the steam generating capacity.
In Loeffler boiler, this problem is solved by preventing water from flowing through the boiler tubes. The steam is generated outside the tubes.