1. Power station boiler: used for power generation, mostly large-capacity, high-parameter boiler, fire chamber combustion, high efficiency, export working medium is superheated steam; 2. Industrial boiler: used for industrial production and heating, most of which are low pressure and low temperature Small-capacity boilers, burning of fire beds, low thermal efficiency, export, working fluid is called steam boiler, hot water boiler is called hot water boiler; 3. marine boiler; 4. locomotive boiler; 5. Steam injection boiler: used for steam injection thermal recovery of heavy oil in oil field, the export working medium is generally high pressure wet steam.