This set of Energy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Fuel Burning”.
1. What is the most important factor that is essential for economical working of a power plant?
a) Abundant fuel input
b) Rotational speed of turbines
c) Efficient transfer of heat energy to water
d) Proper maintenance Ash and other waste handling systems
View Answer
Explanation: The economical working of power plant depends upon factors such as efficient transfer of heat energy to water for generation of steam and efficient combustion of fuel in combustion chamber. Many improvements have been made in design of the furnace to increase the rate of combustion.
2. What type of reaction is burning?
a) Endothermic reaction
b) Exothermic reaction
c) Synthesis reaction
d) Decomposition reaction
View Answer
Explanation: Burning is an exothermic reaction. A fuel is a store of chemical energy that we convert into useful energy to our purposes. For example, we can use the energy stored in natural gas to cook our food. To release this energy, we usually burn the fuel. Burning is a chemical reaction in which the fuel reacts with oxygen gas in air and gives out energy in terms of heat. We call this type of reaction as exothermic reaction.
3. Which type of furnace cannot be used in the modern era plants?
a) Hand fired furnace
b) Electric arc furnace
c) Solar furnace
d) Central warm air furnace
View Answer
Explanation: A hand fired furnace is simple in design, but it cannot be used in modern power plants because of its lower combustion efficiency. It does not respond quickly to fluctuating loads and control of draught is very difficult.
4. How much pounds of CO2 is emitted per million BTU (British thermal unit- common thermal unit) when coal is burnt?
a) 139
b) 117
c) 157
d) 205
View Answer
Explanation: 205 million BTU is the pounds of CO2 that is emitted when coal is burnt. The amount of CO2 produced when a fuel is burned is a function of carbon content of fuel. The heat content, or the amount of energy produced when a fuel is burned, is mainly determined by the carbon(C) and hydrogen (H) content of the fuel.
5. A combustion equipment is a component of ____________
a) Turbine
b) Steam generator
c) Flue gas system
d) Ash handling system
View Answer
Explanation: A combustion equipment is a component of steam generator. It receives the fuel and air proportionals to each other and to the boiler steam demand, mix, ignites and performs other function such as distillation of volatile matter of coal.
6. What was the reason for the poor efficiency of boiler in earlier time?
a) Boilers were set close to grates
b) Poor design of exhaust system
c) Impurities contamination the fuels
d) Lack of proper maintenance
View Answer
Explanation: In earlier times boilers were set very close to the grates and combustion space was limited and hence resulted in smoke and poor efficiency. Later, furnaces were made larger and the boilers were set at higher level above the grates. The hand fired furnace with large combustion space was used to burn a wide variety of coals.
7. Which was first combustion system used for solid fuels?
a) Firing stoker
b) Tangential stoker
c) Grate firing
d) Pulverized fuel firing
View Answer
Explanation: Grate firing was the first combustion system used for solid fuels. It now is used mainly for burning waste and biomass, but also for smaller coal furnaces. Fuel fired per grate area is 1-2 MW/m2, ad maximum grate area is 100m2.
8. The amount of fuel burned depends on ____________
a) Design of burner
b) Depends on air inlet and exhaust system
c) Depends on bed movement velocity
d) Depends on amount of supply of combustion supportive air
View Answer
Explanation: The amount of fuel burned depends on the amount of fuel burned and on the bed velocity movement. The grate area is the total area of grate (a frame of iron bars). The large the grate area, the more fuel can be burned per hour.
9. Which device is used for feeding the fuel automatically to boiler or furnace in power plants?
a) Relay
b) Mechanical stoker
c) Master controller
d) Feed pump
View Answer
Explanation: Mechanical stoker is the device which automatically feeds a solid fuel (such as coal) into combustion chamber of a boiler or furnace, and provides air for the proper combustion; may include a means for automatically removing solid products of combustion.
10. What is used in case, to throw coal into furnace that is set off far from the supply?
a) Speed convey belt
b) Bucket chain
c) Paddle
d) Steam jet
View Answer
Explanation: Steam jet from the boiler or a mechanical catapult may also be used to throw coal into far reach of the furnace. The mechanical means used in the system depend on the design, combinations of screw feed, the conveyor belt, the bucket chain, the paddle and the ram.
11. Where exactly are mechanical stokers used?
a) In transportation of fuels
b) In small capacity plants
c) In large capacity plants
d) For domestic usage
View Answer
Explanation: Mechanical stokers are usually used in large and medium capacity plants. Mechanical stokers are used to fire almost all kinds of coal. This produces less smoke than hand firing. A stoker consists of a power feeding machine and a grate.
12. Which type of stokers has more demand in the market?
a) Spreader stoker
b) Vibrating stoker
c) Travelling stoker
d) Underfeed stoker system
View Answer
Explanation: Spreader stoker systems are receiving the greatest interest and sales in the market. Depending upon the method of introducing the coal into furnace, stokers are mainly classified into spreader stokers, underfeed stokers, vibrating grate stokers and travelling grate stokers.
Sanfoundry Global Education & Learning Series – Energy Engineering.
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