单项选择题
After a normal, or safety shutdown, automatic combustion control systems for an auxiliary boiler are designed to prevent the immediate re-firing of a burner in order for the （）.
A.furnace to be re-purged B.electric charge to buildup in the igniter C.fuel pump to restart D.drum level to stabilize
单项选择题 （） will be used to blow away soot and the combustion products from the tube surfaces.
单项选择题 The correct pH value of boiler water is achieved by continuous addition of a suitable （） to the feed.
单项选择题 A dazzling white burner flame in the boiler furnace indicates （）.
