單項(xiàng)選擇題Fins are installed on the fireside of water-tubes used in waste boiler to（）

A.decrease the velocity of gases flowing past the tubes
B.increase the rate of heat transfer
C.reduce accumulations carbon deposits
D.direct the flow of gases


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1.單項(xiàng)選擇題A smoking burner with a pulsating flame in auxiliary boiler, is an indication that the（）

A.fuel oil supply temperature is normal
B.burner electrode is incorrectly positioned
C.fuel／air ratio is incorrect
D.ignition current is too low

2.單項(xiàng)選擇題The correct procedure for giving an auxiliary boiler a bottom blow, is to begin（）

A.when the boiler has been secured long enough for most solids to settle
B.when the boiler has been cooled to ambient temperature
C.only after raising the water level to within 0~5 inch of the high water cutout only
D.after bypassing the low pressure

3.單項(xiàng)選擇題Bottom blow valves are installed on auxiliary water-tube boilers to （）

A.completely drain the boiler in an emergency
B.prevent sludge from forming in the drum
C.remove floating impurities from the boiler water surface
D.remove settled solids from the water drum

4.單項(xiàng)選擇題A burner responsible for producing black smoke in an automatic auxiliary boiler, would be caused by a （）

A.defective solenoid valve
B.dirty fuel nozzle
C.grounded high tension lead
D.faulty ignition cable connector

5.單項(xiàng)選擇題A firebox explosion in an automatically fired auxiliary boiler may be the result of （）

A.excessive purging before lighting off
B.insufficient trail for ignition period
C.a faulty transformer in the ignition circuit
D.insufficient purging before lighting off