According to fuel types and energy sources can be divided into: coal-fired boilers, oil-fired boilers, gas-fired boilers, atomic energy boilers, waste heat (waste heat) boilers.
According to the structure of the boiler can be divided into: shell boiler (fire tube boiler), water tube boiler, water and fire tube boiler (horizontal quick loading boiler).
According to the way of fuel combustion, it is divided into: layer combustion furnace, boiling furnace and chamber combustion furnace.
According to the flow mode of working medium, it can be divided into spontaneous combustion circulation boiler, forced circulation boiler, direct current boiler and so on.
Among them, industrial boilers generally have a smaller capacity (below 65 tons/hour) and a lower pressure (2.45MPa and below). Most of them use layer combustion. There are a wide variety of structural types and combustion equipment, which are mainly used for steam and heating in industrial production and life.