单项选择题
One of the main purposes of refractories in a boiler furnace is to（）
A.help preheat the air for the furnaces
B.help preheat the feedwater
C.protect economizer from excessive heat
D.prevent excessive furnace heat losses
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相关考题
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单项选择题
What is the first thing you would check on taking over a watch?（）
A.the bilges
B.the periscope
C.the water level
D.the oil pressure -
单项选择题
Soot blowers should be used in proper sequence so that（）
A.excess stresses will not be set up in the boiler
B.the decks will not be covered with soot
C.the soot will be swept toward the uptakes
D.there will not be a loss of steam pressure -
单项选择题
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
