In order to reduce the air temperature in the low temperature air separation unit, various heat exchange equipment are needed for cold and heat exchange in various air separation systems, such as nitrogen water precooler, switching heat exchanger, main heat exchanger, condensing evaporator, subcooler, liquefier, vaporizer, electric heater, etc. These heat exchange equipments are installed in each system of the air separation unit, which are necessary for air liquefaction and gas separation.
According to the principle of heat transfer, the heat exchanger of air separation unit can be divided into three types:
1.Dividingwall type: the cold and hot fluid is separated by the heat transfer wall, the medium does not directly contact in the heat transfer process, and the hot fluid transfers heat to the cold fluid through the heat transfer wall. For example, tube heat exchanger and plate heat exchanger.
2.Heat storage type: the cold and hot fluid alternately flows through the solid heat storage body with sufficient heat capacity. The heat storage body absorbs heat through the superheated fluid. When the cold fluid passes through, the heat storage body releases heat, so as to realize the heat exchange of cold and hot fluid. For example, an accumulator.
3.Mixed type: the heat transfer of cold and hot fluids is realized in the process of direct mixing and contact between the two fluids, such as nitrogen water precooler, etc.