Friday, May 3, 2019

MECHANICAL ENGINEERING MCQ ON BOILER PART - 8

251. For the combustion process to obtain 1 kg of oxygen, how much air is required?

(A) 4.35 kg 

(B) 1kg

(C) 4.76 kg 

(D) None of the mentioned

252. Which of the following is not boiler mountings?

(A) Pressure gauge 

(B) Feed water check valve (NRV)

(C) Soot blower 

(D) Main steam stop valve

253. Hydrogen Sulphide from boiler feed water can be reduced by which of the following process

(A) Deaeration 

(B) Coagulation

(C) Aeration 

(D) None of the mentioned

254. For a given set of operating pressure limits of a Rankine cycle, the highest efficiency occurs for

(A) Saturated cycle 

(B) Superheated cycle

(C) Reheat cycle 

(D) Regenerative cycle

255. Consider the following components

1. Radiation evaporator

2. Economiser

3. Convection evaporator

4. Convection super heater

In case of benson boiler the correct 
sequence of entry of water through these components is

(A) 1, 2, 3, 4 

(B) 1, 2, 4, 3

(C) 2, 1, 3, 4 

(D) 2, 1, 4, 3

256. In pulverised fuel-fired large power boiler, the heat transfer from the burning fuel to the walls of furnace is

(A) By conduction only 

(B) By convection only

(C) By conduction & convection 


(D) Predominantly by radiation

257. Which one of the following statement is not correct in a fluidized bed boiler?

(A) The formation of NO is less than that in the conventional boilers

(B) The combustion temperatures are higher than those in the conventional boilers

(C) Inferior grade of coal can be used without slagging problems

(D) The volumetric heat release rates are higher than those in the conventional boilers

258. Induced draft fans of a large steam generator have

(A) Backward curved blades 

(B) Forward curved blades

(C) Straight or radial blades 

(D) Double curved blades

259. What will you do when there are rapid fluctuations in the outlet steam temperature?

(A) The water level is to be increased

(B) All fuel supply should be cut off
 immediately

(C) Rate of steam generation is
 to be reduced

(D) All of the mentioned

260. Short term overheating usually exhibits

(A) Thick lip longitudinal rupture 

(B) Thin lip longitudinal rupture

(C) Transverse cracks 

(D) Severe pitting


261. Ash handling system is not required in

(A) Pulverized coal-fired boiler 

(B) Coal gas-fired boiler

(C) Traveling grate-fired boiler 

(D) None of the mentioned

262. When high sulphur coal is used in boiler SOx formation can be minimised by the addition of

(A) Silica 

(B) Low sulphur heavy stock oil

(C) Limestone 

(D) None of the mentioned

263. In circulating fluidised bed combustion(CFBC) boiler which type of fan/blower delivers air at the highest pressure

(A) Primary air fan 

(B) Secondary air fan

(C) Tertiary air fan 

(D) Loop seal air blower

264. What is used to control NOx emission, once it is formed

(A) Ammonia 

(B) Silica

(C) Alum 

(D) None of the mentioned

265. What is the value of circulation ration for once-through steam boilers?

(A) 1 

(B) 3 to 10

(C) 4 to 30 

(D) 0.5

266. In steam generators, a stoker acts as one of the following devices, what is this device?

(A) Air preheating device 

(B) Steam superheating

(C) Air superheating device 

(D) Fuel feeding device

267. An apparatus used to reduce the temperature and heat content of superheated steam is called

(A) Steam separator 

(B) Attemperator

(C) Air preheater 

(D) Feed check valve

268. Which of the following varieties of coal is mostly used in steam boilers?

(A) Non-coking bituminous coal 

(B) Brown coal

(C) Peat 

(D) Coking bituminous coal

269. To prevent foaming & priming in boilers which measure should be taken?

(A) Maintain the concentration of solids in boiler water at low levels

(B) Avoid sudden load changes

(C) Avoid high water levels

(D) All of the mentioned

270. As per IS 8753 which should not be used to measure steam & water pressures from the following?

(A) Bourdon type gauges 

(B) Dead Weight gauges

(C) Diaphragm gauges 

(D) All of the mentioned

271. When inspection doors on the walls of boilers are opened, the flame does not leap out because

(A) These holes are small

(B) The flame travels always in the direction of flow

(C) The holes are located beyond the furnace

(D) The pressure inside is negative

272. In the combustion process, the effect of dissociation is to

(A) Reduce the use of excessive air

(B) Reduce the flame temperature

(C) Reduce the proportion of carbon monoxide in gases

(D) Separate the products of combustion

273. Which of the following is gravimetric coal feeder

(A) Rotary feeder 

(B) Screw feeder

(C) Drag chain feeder 

(D) Weight belt

274. What will be the effect of non-condensable gases in steam?

(A) Non-condensable gases reduce the steam temperature & its partial pressure

(B) Non-condensable gases increase the steam temperature & its partial pressure

(C) Non-condensable gases prevent corrosion

(D) None of the mentioned

275. Heating wet steam at constant temperature is heating it at constant

(A) Volume 

(B) Pressure

(C) Enthalpy 

(D) None of the above

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