The vertical steam boiler is composed of the main pressure components such as the head, the drum, the furnace. The grate in this boiler is placed on the upper part of the U-shaped lower foot in the furnace, which increases the radiation heating area. The combustion part of the boiler adopts a double-layer grate combustion chamber, which can increase the pressure quickly. So, it is an ideal equipment for small enterprises and institutions to produce gas, and so on.