The steam boiler is part of a closed loop steam, whereby, after the energy of the steam is used up and it becomes water again, （） is collected and returned back to the boiler for heating up again to steam.

相似题目

• Which of the following statements concerning fire-tube boilers is correct?（）

  A . Combustion gases flow through the tubes B . Flames impinge on the tubes C . Combustion occurs in the tubes D . Water flows through the tube

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• Which of the listed types steam traps operates on the principle that hot water flashes to steam when its vapor pressure is rapidly reduced?（）

  A . Ball float B . Thermostatic C . Bimetallic D . Impulse

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• The internal part of boiler should be cleaned by yard if found （）.

  A . scaled B . worn C . deformed D . rested

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• The water level in a steaming auxiliary boiler will always （）

  A . rise when the steam pressure is increased B . remain constant as long as the feed pump operates C . fall when the steam pressure is decreased D . vary as the steam demand change

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• The purpose of a temperature sensing device installed in the stack of a small automatically fired auxiliary steam boiler is to secure the oil burner（）

  A . in the event of a flame failure B . in the event of a stack fire C . when the water level reach the crown sheet D . when the feed pump discharge pressure drops to a preset minimum

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• What is NOT a function of the steam drum of a marine water-tube boiler（）.

  A . Receives saturated steam from the generating tubes B . Serves as a reservoir of boiler feed water C . Holds internal fittings for separation of moisture from steam D . Collects steam exhausted from the turbine

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• When a boiler is operating, the water level in the gauge glass reads （） when the boiler is shut down.

  A . lower than B . higher than C . as much as D . the same a

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• The valve that prevents water from backing out of the boiler into the feed line is the（）.

  A . bottom-blow valve B . skin valve C . feed-check valve D . feed-stop valve

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• In an auxiliary boiler steam and water system, the highest pressure will be in the （）.

  A . steam stop valve B . dry pipe C . feedwater system D . generating tube

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• （）, iea steam cooler, may be filled in the boiler system to control the superheated steam temperature.

  A . An economizer B . An attemperator C . A water dram D . A down-comer tube

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• The maximum pressure developed by a waste heat boiler is determined by the main engine exhaust （）.

  A . gas composition B . gas temperature C . pressure D . timing

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• A （） boiler is an auxiliary boiler sometimes included in a steamships installation for supplying steam to auxiliaries in port.

  A . monkey B . donkey C . waste heat D . mai

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• Steam fog is most likely to occur on the Mississippi and Ohio Rivers in（）.

  A . spring，around late evening B . spring，around early evening C . fall，around early morning D . fall，around midday

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• Which of the following statements concerning the water tube and fire tube boilers is not true?（）

  A . natural circulation of the water in the water tube boiler is better than that in the fire tube boiler B . for the same output the water tube boiler will carry less mass of water compared with the fire tube boiler C . the water tube boiler will cost shorter time for steam raising D . the water tube boiler require lower skill in operating and maintaining

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• Which one is not the normal operation for boiler shutdown?（）

  A . Carry out soot blowing if permissible B . Change fuel supply to diesel oil C . Close steam stop valves on boiler when pressure is reduced D . Drain boiler empty when it has cooled dow

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• （） should be tested and adjusted when the boiler survey is carried out.

  A . The boiler oil tank B . The steam pipe C . The fire side D . The safety valve

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• The boiler is fired （） the demand for steam exceeds that available from exhaust gas heating.

  A . whenever B . however C . wherever D . whether

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• The purpose of the safety relief valves installed on an auxiliary boiler is to （）.

  A . relieve excess fuel oil pressure during the “off” fire cycle B . admit water to the dry pipe C . throttle the forced draft fan output for proper combustion D . reduce excess steam pressure in the boiler

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• The（） is a smaller valve fitted in the auxiliary steam supply line, and is usually of the non-return type.

  A . main stem stop valve B . auxiliary steam stop valve C . feed check or control valve D . blow down valve

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• The furnace of an oil fired boiler should be （） before the operating burner is lit.

  A . filled with water B . purged C . cleared of air D . None of the above is true

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• The purpose of the programmed purge cycle on an automatically fired auxiliary boiler is to（）

  A . cool the furnace to prevent pre-ignition B . remove explosive vapors from the furnace C . evaporate accumulated unburned fuel oil D . provide sufficient air in the furnace to allow ignition of the fuel

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• As for an oil-fired boiler if at a normal steaming condition and water goes out of sight in gauge glasses the action you should take is: （） (1) secure oil to fires (2) increase feed pump pressure

  A . （1） B . （1）and（2） C . （2） D . neither（1）nor（2）

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• The steam supply to the heaters is controlled by the （), which must be sited in close p

  The steam supply to the heaters is controlled by the (), which must be sited in close proximity to the injection pumps, either just ahead of them or in the fuel return line as shown. A. flowmeter B. piezometer C. manometer D. viscosimeter

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• As for an oil-fired boiler if at a normal steaming condition and water goes out of sight in gauge glasses the action you should take is: (1) secure oil to fires; (2) increase feed pump pressure.

  A.(1) B.(1) and (2) C.(2) D.neither (1) nor (2)

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