76. What are the methods adopted to remove’ S02 flue gases?

1. Wet scrubbing
2. Solid absorbent
3. Catalytic oxidation

77. Write about C02 recorders?

In thermal power plants, it is necessary to keep the concentration Of C02 as low is necessary as possible. To achieve this, a constant recording of concentration Of C02

These recorders are based on the three different principles, as given below.

1. Thermal conductivity cell
2. Chemical absorption cell
3. Density balance

78. Name some of the automatic controlling methods for feed water?

1. Single element pilot operated system
2. Single element self operated system
3. Two element pilot operated system
4. Three element pilot operated system

79. What is the purpose of automatic, combustion c61ritrol?

The main purpose of automatic combustion’ control system is to maintain load against demand, to prevent smoke, to increase boiler house efficiency, to carry out routine adjustments and to provide interlocking safe guards.

80. What are the appliances known as boiler accessories?

The appliances used to increase the efficiency of the boiler are known as boiler accessories.
The important boiler accessories are

1. Economiser 2. Superheater 3. Air preheater 4. Feed pump 5. Injector

81. What are the methods adopted to remove SO2 from due gases?

1. Wet scrubbing
2. Solid absorbent
3. Catalytic oxidation

82. Write about C02 recorders?

In thermal power plants, it is necessary, to keep the concentration of C02 as low
as possible. To achieve this ‘ a constant recording of concentration of C02 is necessary.

These recorders are based on the three different principles, as given below.

1. Thermal conductivity cell
2. Chemical absorption cell
3. Density balance

83. What is the necessity of Automatic controls for feed water?

The electrical load on power plant varies irregular manner. The automatic man control provided at a steam power plant successfully meets over the variable load. The automatic control for feed water is necessary sine the supply of feedwater depends upon plant load.

84. Name some of the automatic controlling methods for feed water?

• A single element pilot operated system
• Single element self operated system
• Two element pilot operated system
• Three element pilot operated system

85. What is the purpose of automatic combustion control?

The main purpose automatic combustion control system is to maintain load adjust demand, to prevent smoke, to increase boiler house efficiency, to carry out routine adjustments and to provide interlocking safe guards.

86 What is the use of air preheater?

Air pre heater is used to transfer heat from the flue gases to the air before it passes into the furnace for combustion. It is placed between the economizer and chimney. The overall efficiency of the plant may be increased by 10 per cent by the use of air preheater.

87. Write about boiler mountings?

The devices used for the efficient operation, proper maintenance, and safe operation boiler mountings.

The different boiler mountings are

1. Water gauge (or) water level indicator
2. Pressure gauge (or) steam gauge
3. Safety valves
4. Fusible plug
5. Stop valve
6. Blow off cock
7. Feed check valve.

88. What is meant by boiler trial?

Steam is generated in boilers under certain conditions of feed water and exists as steam while a certain amount of fuel is burnt. To study the performance of boiler, some experiments are conducted by operating, the boiler for a certain length of time and recording the data. This procedure is known as boiler trial.

89. State the objective of boiler trial?

1.To determine the thermal efficiency of the boiler when working at a definite pressure.
2.To draw up heat balance sheet for the boiler to check the performance of the boiler.

90. Define demand factor?

• Demand factor is defined as the ratio of maximum demand to connected load.
• Connected load is the sum of ratings in kW of equipment installed in the consumer’s premises.
• Maximum demand is the maximum load, which a consumer uses at any time.

91. Define load curve?

Load curve is a graphical representation between load in kW and time in hours. It. shows variati6n of load at the power station. The area under the load curve represents the energy generated in a particular period.

92. Define load factor?

Load factor is defined as the ratio of average load to the peak load (or) maximum demand.

93. What includes fixed cost?

Fixed cost includes the following cost.

1. Cost of land 2. Cost of building
3. Cost of equipment 4. Cost of installati6n
5. Interest 6. Depreciation cost
7. Insurance 8. Management cost

94. What includes operating cost?

Operating cost includes the following cost.

1. Cost of fuel 2. Cost of operating labour,
3. Cost of maintenance labours and materials.
4. Cost of supplier like

Water for feeding boilers, for condenser and for general use.

• Lubrication oil and, grease.
• Water treatment chemicals.

95. What is the need of depreciation cost?

Depreciation cost is the amount to be set aside per year from the income of the plant to meet the depreciation caused by the age of service, wear and tear of the machinery and equipments. Depreciation amount collected every year helps in replacing and repairing the equipment.

96. Write about atomic number?

The nucleus contains protons and neutrons. The number of protons in a given atom is an atomic number (Z). The atomic number for H is 1 and He is 2.

97. Write about isotopes of an element?

Some elements have the same number of protons in the nucleus but different number of neutrons. As a result, these elements have the same atomic number but different mass number. Such type of elements which ‘ have the same atomic number – same number of protons the same chemical properties but different mass numbers due to different number of neutrons, are known as I the isotopes of an element.

98. What are the requirements to sustain fission process?

• The bombarded neutrons must have sufficient energy to cause fission
• The number of neutrons produced must be able to create the rate of fission
• The fission process must generate energy
• The fission process must be controlled

99. Define multiplication factor of a fission process.

k =number of neutrons of any one generation/number of neutrons of immediately preceding generation.

100. Define fertile materials and breeding in reactors

There are materials like U235 and Th232 which are not fissile but can be converted into fissile materials by the bombardment of neutrons. Such materials are known as fertile materials.
The process of converting more fertile material into fissile material in a reaction is known as breeding.