126. The diameter of fire tubes in Cochran boiler is of the order of
(a) 2 cm
(b) 6 Cm ,
(C) 8 cm
(d) 12 cm
(e) 15 cm.
Ans: b
127. In a recuperative air preheater, the heat is transferred
(a) from a metal wall from one medium to another
(b) from heating an intermediate material and then heating the air from this material
(c) by direct mixing ,
(d) heat is transferred by bleeding some gases from furnace
(e) none of the above.
Ans: a
128. A safety valve in a locomotive starts leaking. The leaking medium will be
(a) water
(b) dry steam
(c) wet steam
(d) super heated steam
(e) supersaturated steam.
Ans: d
129. The temperature of flue gases at air heater outlet should be
(a) 100°C
(b) above dew-point temperature of flue gases
(c) below dew-point temperature of flue gases
(d) less than wet bulb temperature of flue gases
(e) above wet bulb temperature of flue gases.
Ans: b
130. In regenerative air preheater, the heat is transferred
(a) from a metal wall from one medium to another
(b) from heating an intermedia teanaterial and then heating the air from this material
(c) by direct mixing
(d) heat is transferred by bleeding some gas from furnace
(e) none of the above.
Ans: b
131. In designing air preheater, the important design consideration is that
(a) approach temperature should be as low as possible
(b) handling and maintenance should be easier
(c) heat transfer area should be optimum
(d) stack gases should not be cooled to the dew point
(e) none of the above.
Ans: d
132. The pressure of reheat steam after passing through reheated compared to inlet condition is
(a) more
(b) less
(c) equal
(d) may be more or less depending on capacity of reheated
(e) none of the above.
Ans: b
133. The function of injector used in small capacity boilers is to
(a) create vacuum
(b) inject chemical solution in feed pump
(c) pump water, similar to boiler feed pump
(d) add make up water in the system
(e) none of the above.
Ans: c
134. The safety valve at superheater as compared to drum safety valve setting is set at
(a) higher value
(b) lower value
(c) same value
(d) any value
(e) none of the above.
Ans: b
135. The height of chimney in a power plant is governed by
(a) the draft to be created
(b) limitation of construction facilities
(c) control of pollution
(d) quantity of flue gases to be handled
(e) all of the above.
Ans: c
136. Steam exhaust from high pressure turbine is reheated in
(a) boiler drum
(b) superheater tubes
(c) economiser
(d) a separate coil
(e) a separate coil located in convection path.
Ans: e
137. Vacuum for reciprocating steam engines compared to steam turbines is
(a) more
(b) equal
(c) less
(d) could be more or less depending on the size of plant
(e) none of the above.
Ans: c
138. Expanding steam to a very low pressure (high vacuum) in steam engines is
(a) desirable
(b) economical
(c) essential
(d) optional
(e) uneconomical.
Ans: e
139. In locomotives, the drought is produced by
(a) chimney
(b) induced draft fan
(c) both combined (a) and (b)
(d) steam jet drought
(e) none of the above.
Ans: d
140. Reheating of steam under ideal conditions takes place at constant
(a) entropy
(b) enthalpy
(c) pressure
(d) temperature
(e) all of the above.
Ans: d
141. The maximum discharge through a chimney occurs when the height of chimney is
(a) infinitely long
(b) around 200 meters
(c) equal to the height of the hot gas column producing drought
(d) outside temperature is very low
(e) more than the tallest building nearby.
Ans: c
142. Proximate analysis of fuel is determination of percentage of
(a) carbon, hydrogen, nitrogen, sulphur, moisture
(b) fixed carbon, ash, volatile matter, moisture
(c) higher calorific value
(d) lower calorific value
(e) rough analysis.
Ans: b
143. Which device is used in thermal power plants to reduce level of pollution
(a) induced draft fan
(b) smoke meter
(c) chimney
(d) precipitator
(e) pulveriser.
Ans: d
144. Bomb calorimeter is used to determine
(a) Higher calorific value at constant volume
(b) Lower calorific value at constant volume ,
(c) Higher calorific value at constant pressure
(d) Lower calorific value at constant pres¬sure
(e) None of the above.
Ans: a
145. Ultimate analysis of fuel is determination of percentage of
(a) carbon, hydrogen, nitrogen, sulphur, moisture
(b) fixed carbon, ash, volatile matter, moisture
(c) higher calorific value
(b) lower calorific value
(e) best analysis.
Ans: a
146. For combutsion of a fuel, following is essential
(a) correct fuel air ratio
(b) proper ignition temperature
(c) 02 to support combustion
(d) all the three above
(e) none of the above.
Ans: d
147. Spontaneous combustion is a phenomenon in which
(a) all the fuel burns instantaneously producing high energy release
(b) fuel burns with less air
(c) coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
(d) explosion in furnace
(e) none of the above.
Ans: c
148. The economiser is used in boilers to
(a) increase thermal efficiency of boiler
(b) economise on fuel
(c) extract heat from the exhaust flue gases
(d) increase flue gas temperature
(e) to heat feed water by bled steam.
Ans: a
149. An economizer in a boiler
(a) increases steam pressure
(b) increases steam flow
(c) decreases fuel consumption
(d) decreases steam pressure
(e) increases life of boiler.
Ans: c
150. 02 content in atmospheric air on volume basis is
(a) 21%
(b) 23%
(d) 30%
(d) 40%
(e) 70%.
Ans: a