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（）
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
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（）
单项选择题 Which of the lists forms of heat transfer, if any, is illustrated by the flow of combustion gases through a boiler?（）
