Heat transfer equipment refers to the equipment that makes heat transfer from hot fluid to cold fluid, heat transfer equipment is widely used in oil refining, chemical, light industry, pharmaceutical, machinery, food, processing, power and atomic energy industry sectors. Usually, in some chemical plants, equipment investment, heat exchangers accounted for 30% of the total investment; in modern refineries, heat exchangers account for about all the process equipment investment of more than 40%; in seawater desalination industrial production, almost all equipment are composed of heat exchangers. The advanced, rational and reliable operation of the heat exchanger directly affects the quality, quantity and cost of the product.

    According to different purposes of use, the heat exchanger can be divided into four categories: heater, cooler, evaporator, condenser. According to the principle of heat transfer and heat exchange can be divided into wall heat exchanger, mixed heat exchanger, heat storage heat exchanger (hot and cold fluid direct contact), a liquid heat carrier indirect heat exchanger four kinds. A measure of the quality of a heat exchanger standard is the high efficiency of heat transfer, fluid resistance, strength enough, reasonable structure, safe and reliable, save materials, low cost, manufacturing, installation, maintenance is convenient. In the petroleum, chemical production intermediate wall heat exchanger widely used.

    Heat exchange equipment can be divided into three categories according to the traditional way.

    1. Hybrid heat exchanger

    The use of cold and hot fluids can be directly mixed with the role of the exchange of heat such exchangers simple structure, but inexpensive, often made into towers. Two kinds of media that allow completely mixed and different temperatures, in the process of direct contact to complete the transfer of its heat. For example: cold water tower (cool water tower), granulation tower, air drying device, fluidized bed, etc..

    2. Regenerative heat exchanger

    In this type of heat exchanger, energy transfer is done through a heat accumulator such as a lattice brick or filler. The hot fluid is first allowed to pass through, storing the heat in the heat accumulator, and then the cold fluid is allowed to pass through, taking the heat away. As the two fluids alternate conversion input, it is inevitable that there is a small part of the fluid mixed with each other, causing fluid "pollution".

    Regenerative heat exchanger compact structure, inexpensive, large heat transfer surface per unit volume, it is more suitable for gas - gas heat exchange occasions. Mainly used in petrochemical production of raw material gas conversion and air waste heat. The structural characteristics of the rotary heat storage heat exchanger is to achieve continuous operation, heat storage body in the heat exchanger is generally used to shape the plate or wire mesh assembly of the fan-shaped cabinet, the external metal shell sealed by the metal shell, and every minute 1 ~ 4 rotation has been rotated at a slow speed for continuous heat transfer.

    3?Inter-wall heat exchanger

    The so-called inter-wall heat exchanger, refers to the two different temperatures of the fluid in the fixed wall (called the heat transfer surface) separated by the flow of space, through the wall surface has heat conduction and convective heat transfer on the surface of the wall for the transfer of heat. Participate in the heat transfer fluid will not mix, transfer process is continuous and stable. Between the wall heat transfer surface of the heat exchanger mostly used in good thermal conductivity of metal manufacturing. On some occasions, because of the need for corrosion resistance, but also with non-metallic (such as graphite, polytetrafluoroethylene, etc.) manufacturing. This is widely used in industrial manufacturing of a class of heat exchanger. Cold, hot fluid is separated by a solid wall wall through the wall surface for heat transfer.

    According to the shape and structural characteristics of the heat transfer surface it can be divided into.

    (1) Tube heat exchanger: such as casing type, spiral tube type, shell and tube type, heat pipe type and so on.

    (2) Plate surface heat exchanger: such as plate type, spiral plate type, plate shell type, etc.

(3) Extended surface heat exchanger: e.g. plate fin type, tube fin type, reinforced heat transfer tube, etc.