Because of the different properties of the waste heat smoke, the type and structure of the waste heat boiler are different.
1. According to the structure characteristics of waste heat boiler: Tube - shell waste heat boiler and flue type waste heat boiler are used. 2. According to the dust content and characteristics of the flue gas imported from the waste heat boiler: (1) The waste heat boiler in the flue gas not more than 20g/Nm3 is the first kind of waste heat boiler. (2) The waste heat boiler in the flue gas more than 20g/Nm3 and not more than 70g/Nm3 is the second kind of waste heat boiler. (3) The waste heat boiler which contains more dust than 70g/Nm3 in the flue gas is the third kind of waste heat boiler. (4) the waste heat boiler with adhesive smoke and dust in the flue gas is the fourth kind of waste heat boiler. (5) the waste heat boilers with strong corrosion components or toxic fumes are the fifth kinds of waste heat boilers.
3. Steam pressure grade produced by waste heat flue gas boiler At present, the waste heat boiler adopts five kinds of steam water systems, such as single pressure, double pressure, double pressure reheat, three pressure and three pressure reheat. 4. Classified according to the layout of the heated surface: The horizontal layout waste heat boiler and the vertical arrangement waste heat boiler. 5. According to the flow characteristics (working principle) of the working fluid in the evaporation and heating surface (working principle): (1) Natural circulation waste heat boiler: the flue gas is the tube cluster in the horizontal direction that flows through the vertical direction. The density difference between the water vapor mixture in the tube and the cold water in the tube is the motive force to maintain the natural circulation of the steam water mixture in the evaporator. (2) Forced circulation waste heat boiler: the flue gas usually always flows vertically through the tube cluster in the horizontal direction. The circulation pump is used to ensure the constant circulation flow in the evaporator. (3) DC waste heat boiler: DC waste heat boiler by feed water pump pressure head once through each heating surface into superheated steam. In the evaporation heating surface, the flow of the working fluid is realized by the pressure head of the feed water pump.