单项选择题
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
单项选择题 The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to（）
单项选择题 Diesel engine waste heat boiler construction is usually of the fire-tube or（）
单项选择题 Auxiliary boilers are divided into several classifications, one of which is（）