Tube heating furnace is a process heating furnace used in petroleum refining, petrochemical and chemical and chemical fiber industries, which has several features that are not found in other industrial smelting furnaces. Basic features: has a combustion chamber surrounded by refractory materials, using the heat generated by the combustion of fuel to heat the material of a device. Tube heating furnace characteristics. 1) The heated material flows inside the tube, so it is limited to heating gases or liquids. (2) heating method for the direct fire type. (3) burning only liquid or gaseous fuel. (4) long cycle continuous operation, uninterrupted operation. Working Principle: The working principle of tube heating furnace is: the fuel is burned in the radiation chamber of the tube heating furnace (very few in a separate combustion chamber), and the heat released is mainly transferred to the furnace tube through radiation heat transfer and convection heat transfer, and then transferred to the heated medium through conduction heat transfer and convection heat transfer.   Main features Compared with other equipment of oil refinery, the special feature of tubular heating furnace is that it is heated directly by flame; compared with general industrial furnace, the tube of tubular heating furnace is subjected to high temperature, high pressure and medium corrosion; compared with boiler, the medium in tubular heating furnace is not water and steam, but flammable, explosive, easy to crack, easy to coke and more corrosive oil and gas, which are the main features of tubular heating furnace. What are the main parts of the tube heating furnace? Tube heating furnace mainly includes furnace tube, furnace tube connector and supporting parts, steel structure, furnace lining, waste heat recovery system, burner, soot blower, chimney, chimney baffle, various butterfly valves, doors (fire watch door, manhole door, explosion-proof door, cleaning hole door and loading hole door, etc.) and instrument receiver (thermocouple casing, pressure measuring tube, fire extinguishing steam pipe, oxygen analyzer receiver and flue gas sampling port receiver, etc.). How is the tube heating furnace classified? According to the function can be divided into: heating type and heating - reaction type two categories. Heating type tube furnace: atmospheric furnace, depressurized furnace, various fractionation tower feed heating furnace, tower bottom reboiling furnace, coking furnace, reforming furnace and hydrogenation furnace and other kinds of reactor (tower) feed heating furnace. Heating - reaction type tube furnace: hydrogen production furnace, ethylene cracking furnace, etc. According to the main heat transfer mode is divided into: pure convection furnace, pure radiation furnace, radiation - convection type furnace and double-sided radiation furnace. According to the furnace type can be divided into: cylinder furnace, vertical furnace and large box-type furnace three categories.