Steam Boilers

41. For burning 1 kg of carbon to CO as per chemically correct combusiton, amount of air required is

1. 1 kg
2. 4/3kg
3. 8/3kg
4. 2 kg
5. 16/3 kg.

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42. For combutsion of a fuel, following is essential

1. correct fuel air ratio
2. proper ignition temperature
3. 02 to support combustion
4. all the three above
5. none of the above.

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43. For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has

1. more heating surface
2. less heating surface
3. equal heating surface
4. heating surface depends on other parameters
5. none of the above.

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44. For water, at pressures below atmospheric,

1. melting point rises slightly and boiling point drops markedly
2. melting point rises markedly and boiling point drops markedly
3. melting point drops slightly and boiling point drops markedly
4. melting point drops slightly and boiling point drops slightly
5. none of the above.

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45. Fusible plug for boilers is made of fusible metal containing tin, lead, and

1. bismuth
2. copper
3. aluminium
4. nickel
5. iron.

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46. Gardually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of

1. higher effectiveness of boiler
2. high calorific value coal being burnt
3. fouling of heat transfer surfaces
4. raising of steam temperature
5. leakage of air.

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47. Green coal, in order to be burnt, must be

1. heated sufficiently
2. burnt in excess air
3. heated to its ignition point
4. burnt as powder
5. burnt as lumps.

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48. Gusset stays in a boiler are provided to

1. prevent the bulging of flat surfaces
2. avoid explosion in furnace
3. prevent leakage of hot flue gases
4. support furnace freely from top
5. prevent atmospheric air leaking into furnace.

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49. Hard coke is produced by carborisation of coal at

1. atmospheric temperature
2. 500-600°C
3. 70O-850°C
4. 95O-1100°C
5. 120O-1500°C.

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50. Hard coke is used in

1. cement industry
2. thermal power plant
3. blast furnace
4. domestic use
5. locomotives

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