A、to raise water level
B、only while making steam
C、to remove scum
D、when fire are secured
更多“The donkey boiler may be given a bottom blow （）”相关的问题
A、one to supply steam to the main propulsion turbine B、an auxiliary boiler C、A and B D、neither A nor B
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
A、caustic embrittlement of the boiler metal B、acidic corrosion of the boiler metal C、hard scale deposits on the boiler tubes D、etching of the heat exchange surfaces
A、drop as the boiler warms up B、rise as the boiler warms up C、remain unchanged until the boiler is hot enough D、rise and fall with the steam demand
A、high steam pressure in the boiler B、abnormally high feed water temperature C、abnormally high boiler water temperature D、steam demand exceeding feed pump capacity
A、precipitate silica from solution B、reduce corrosion in the heating coil C、prevent clogging and erosion in the coil D、maintain zero water hardness
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
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