steam boilers engines nozzles and turbines MCQs – Page 8

Practise focused steam boilers engines nozzles and turbines questions with marked answers for exam preparation and subject revision.

steam boilers engines nozzles and turbines Mcqs
141. In a throttling process________________?
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A. steam volume remains constant

B. steam pressure remains constant

C. steam entropy remains constant

D. steam temperature remaisn constant

E. steam enthalpy remains constant
142. Calorific value of coal is of the order of _______________________?
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A. 8000-10,000 kcal/kg

B. 800-1200 kcal/kg

C. 200-400 kcal/kg

D. 5000-8000 kcal/kg

E. 2000-4000 kcal/kg
143. Which is not the correct statement about moisture in coal ______________________?
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A. it increases thermal efficiency

B. inherent moisture and surface moisture are different things

C. in some coals moisture may be present upto 40%

D. moisture in coal is removed before firing by heating it with hot air

E. some moisture in coal helps in better burning which is not possible with completely dry coal

144. Overfire burning is the phenomenon of _____________________?
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A. fuel bed firing

B. supply of excess, air

C. burning CO and unburnts in upper zone of furnace by supplying more air

D. supply of excess coal

E. none of the above

145. Tertiary air is the air used to____________________?
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A. supply air for ignitors

B. cool the scanners

C. transport and dry the coal

D. provide air around burners for obtaining optimum combustion

E. convert CO (formed in lower zone of furnace) into C02 at higher zone
146. Primary air is the air used to__________________?
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A. transport and dry the coal

B. convert CO (formed in lower zone of furnace) into C02 at higher zone

C. provide air around burners for obtaining optimum combustion

D. none ot the above

E. air-delivered by forced draft fan

147. On Mollier chart, flow through turbine is represented by ________________?
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A. straight inclined line

B. horizontal straight line

C. none of the above

D. vertical straight line

E. curved line

148. Ultimate analysis of fuel is determination of percentage of____________________?
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A. lower calorific value

B. higher calorific value

C. best analysis

D. carbon, hydrogen, nitrogen, sulphur, moisture

E. fixed carbon, ash, volatile matter, moisture

149. The heat loss in a boiler takes place in the form of________________?
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A. heat carried away by flue gases

B. moisture present in fuel and steam formed by combustion of hydrogen in fuel

C. all of the above

D. heat carried away by ash

E. radiation

150. Pulverized fuel is used for___________________?
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A. stoker fired boilers

B. better burning

C. medium sized units

D. more calorific value

E. less radiation loss

151. Deaeration of feed water is carried out because it reduces ____________________?
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A. weight of water to be handled

B. corrosion caused by oxygen

C. pH value of water

D. cavitation of .boiler feed pumps

E. heat transfer coefficient

152. The three Ts for good combustion are____________________?
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A. thorough mixing, total air, and temperature

B. total air, time, and temperature

C. temperature, time, and turbulance

D. none of the above

E. total air, true fuel, and turbulance

153. In designing air preheater, the important design consideration is that_________________?
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A. stack gases should not be cooled to the dew point

B. handling and maintenance should be easier

C. heat transfer area should be optimum

D. approach temperature should be as low as possible

E. none of the above

154. Which is not correct statement about effect of sulphur in fuel ___________________?
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A. it erodes furnace walls

B. it helps in electrostatic precipitation of ash in flue-gases

C. it has heating value

D. it leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low

E. none of the above

155. The number of drums in Benson steam generator is_________________?
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A. two

B. none of the above

C. no drum

D. one

E. one steam drum and one water drum

156. An economiser in a boiler______________________?
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A. increases life of boiler

B. decreases fuel consumption

C. increases steam pressure

D. decreases steam pressure

E. increases steam flow

157. Which is not correct statement about pulverised fuel firing ?
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A. separate mills are required to powder the coal

B. heat release can be easily controlled

C. it is the best technique for burning high ash content fuel having low fusion ash

D. fuel burns economically

E. high burning rate is possible

158. Evaporative capacity of boiler is expressed as____________________?
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A. steam pressure produced

B. kg of steam produced

C. kg of fuel fired

D. kg of steam produced per kg of fuel fifed

E. kg of water evaporated

159. The major axis of elliptical manholes on the shell should be provided___________________?
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A. vertically

B. circumferentially

C. on dished end

D. anywhere

E. longitudinally

160. Film boling occurs at _______________________?
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A. very low pressure

B. very high pressures

C. medium pressures

D. none of the above

E. atmospheric pressures