Question 11 : Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.
1. 0.5
2. 500
3. 10
4. 50
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Question 12 : Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the
1. requirement of large volume of combustion chamber
2. incomplete combustion of coal
3. risk of explosion
4. chances of clinker formation
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Question 13 : High excess air in combustion of fuels results in
1. smoky flame
2. increased fuel consumption
3. incomplete combustion
4. none of the mentioned
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Question 14 : Which of the following is not a by-product recovered in a high temperature coal carbonisation plant?
1. Benzol
2. Ethylene
3. Pitch-cresosote mixture (PCM)
4. Naphthalene
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Question 15 : Bunsen burner is an example of a/an __________ burner.
1. inside mixing/premix type
2. submerged combustion
3. rotary cup
4. outside mixing/diffusion flame/nozzle mix type
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Question 16 : _________ has the widest inflammability limit (explosion limit) of all the gases.
1. Carbon monoxide
2. Methane
3. Hydrogen
4. Acetylene
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Question 17 : Presence of free moisture in coal during its high temperature carbonisation
1. increases the loss of fine coal dust from the ovens when charging
2. protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls
3. reduces the coking time
4. none of the mentioned
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Question 18 : The temperature at which plastic layer formation takes place during carbonisation of coal varies from __________ °C.
1. 100-150
2. 350-450
3. 700-850
4. 550-650
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Question 19 : Gobar gas is produced by the __________ of 'gobar' (cow dung).
1. Fermentation
2. Condensation
3. Combustion
4. Distillation
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Question 20 : __________ of the coal is the basis for Seylor's coal classification.
1. Proximate analysis
2. Calorific value
3. Ultimate analysis
4. Caking index
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