176. Pulverized fuel is used for
(a) better burning
(b) more calorific value
(c) less radiation loss
(d) medium sized units
(e) stoker fired boilers.
Ans: a
177. Calorific value of coal is of the order of
(a) 200-400 kcal/kg
(b) 800-1200 kcal/kg
(c) 2000-4000 kcal/kg
(d) 5000-8000 kcal/kg
(e) 8000-10,000 kcal/kg.
Ans: c
178. Evaporation capacity of boiler is expressed as
(a) kg of steam produced
(b) steam pressure produced
(c) kg of fuel fired
(d) kg of steam produced per kg of fuel fifes
(e) kg of water evaporated.
Ans: d
179. Boiler parameters are expressed by
(a) tonnes/hr. of steam
(b) pressure of steam in kg/cm2
(c) temperature of steam in °C
(d) all of the above
(e) none of the above.
Ans: d
180. The condition of steam in boiler drum is always
(a) dry
(b) wet
(c) saturated
(d) supersaturated
(e) superheated.
Ans: b
181. The balanced draft furnace is one using
(a) induced draft fan and chimney
(b) induced draft fan and forced draft fan
(c) forced draft fan and chimney
(d) any one of the above
(e) none of the above.
Ans: b
182. In ordered obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
(a) remain unaffected
(b) improve
(c) worsen
(d) may improve/worsen depending on size
(e) unpredictable.
Ans: c
183. Maximum energy loss in a boiler occurs due to
(a) unburnt carbon in ash
(b) incomplete combustion
(c) ash content
(d) flue gases
(e) radiation losses.
Ans: d
184. Overtire burning is the phenomenon of
(a) supply of excess, air
(b) supply of excess coal
(c) burning CO and unburnt in upper zone of furnace by supplying more air
(d) fuel bed firing
(e) none of the above.
Ans: c
185. Which is not the correct statement about moisture in coal
(a) inherent moisture and surface moisture are different things
(b) in some coals moisture may be present upto 40%
(c) some moisture in coal helps in better burning which is not possible with completely dry coal
(d) it increases thermal efficiency
(e) moisture in coal is removed before firing by heating it with hot air.
Ans: d
186. De aeration of feed water is carried out because it reduces
(a) cavitation of .boiler feed pumps
(b) corrosion caused by oxygen
(c) heat transfer coefficient
(d) pH value of water
(e) weight of water to be handled.
Ans: b
187. A super critical boiler is one that operates above the pressure and temperature of following values
(a) 100 kg/cm2 and 540°C
(b) 1 kg/cm2 and 100°C
(c) 218 kg/cm2 abs and 373°C
(d) 218 kg/cm2 abs and 540°C
(e) 100 kg/cm2 abs and 373°C
Ans: c
188. Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
(a) increases
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: b
189. The steam temperature with increase in load in case of a boiler fitted with radiation superheated
(a) increases
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) unpredictable.
Ans: b
190. During storage, the heating value of coal
(a) increases
(b) decreases
(c) remains constant
(d) may increase or decrease depending upon the method of storage
(e) none of the above.
Ans: b
191. The relative heat absorption for successively added equal areas of boiler convection heating surfaces
(a) increases
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: b
192. Film boiling occurs at
(a) very low pressure
(b) atmospheric pressures
(c) medium pressures
(d) very high pressures
(e) none of the above.
Ans: d
193. Fire tube boilers are limited to a maximum design working pressure of
(a) 1 kg/cm
(b) 6 kg/cm
(c) 17 kg/cm2
(d) 100 kg/cm2
(e) 250 kg/cm2.
Ans: c
194. For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has
(a) more heating surface
(b) less heating surface
(c) equal heating surface
(d) heating surface depends on other parameters
(e) none of the above.
Ans: a
195. In water wall furnace, the heat is transferred to the water-walls by
(a) convection
(b) radiation
(c) conduction
(d) radiation and conduction
(e) radiation and convection.
Ans: b
196. Relative percentage of heat absorbed through the heat transfer of
(i) furnace water wall,
(ii) boiler bank,
(Hi) superheated,
(iv) economizer,
(v) air heater of a typical boiler of 200 MW capacity would be of the order of
(a) 48:20:15:7:10
(b) 10:7:15:20:48
(c) 20:48:7:15:10
(d) 7:15:20:10:48
(e) 48:15:10:7:20.
Ans: a
197. The feed check valve is used in order to
(a) regulate flow of boiler water
(b) check level of water in boiler drum
(c) recirculate unwanted feed water
(d) allow high pressure feed water to flow to drum and not allow reverse flow to take place
(e) none of the above.
Ans: d
198. The size of a boiler drum in pulverized fuel fired boiler,as its size and capacity, (steam pressure and flow ratings) increase
(a) increases
(b) decreases
(c) remains unchanged
(d) increases/decreases depending on steam temperature requirements
(e) unpredictable.
Ans: b
199. Feed water conditioning in thermal power plants in done to
(a) reduce hardness and for removal of solids
(b) increase efficiency-of thermal power plant
(c) increase heat transfer rate
(d) increase steam parameters
(e) all of the above.
Ans: a
200. The basic job of feed water treatment in boilers is to overcome the problem of
(a) corrosion
(b) scale
(c) carryover
(d) embitterment
(e) all of the above.
Ans: e