Several major categories of heat exchanger are introduced

Heat transfer equipment is to transfer heat from the hot fluid to the cold fluid equipment, heat exchanger is widely used in oil refining, chemical industry, light industry, machinery, pharmaceutical, food processing, power, and atomic energy industry sector. Usually, in some chemical plant equipment investment, heat exchanger, accounting for 30% of the total investment; in modern refineries, these heat exchangers accounted for about 40% of all the process equipment investment; in the desalination industry, almost all the equipment is composed of heat exchanger. The advanced nature, rationality and reliability of the heat exchanger directly affect the quality, quantity and cost of the product.

According to different purposes, the heat exchanger can be divided into four categories: heater, cooler, evaporator, condenser. According to the heat transfer principle and realize the exchange of different forms can be divided into recuperative heat exchanger, heat exchanger, heat exchanger (direct contact with the cold and hot fluid), indirect liquid heat carrier of the heat exchanger four. The standard for measuring the quality of a heat exchanger is that the heat transfer efficiency is high, the fluid resistance is small, the strength is enough, the structure is reasonable, the safety is reliable, the material is saved, the cost is low, the manufacture, the installation and the maintenance are convenient. It is the most widely used in oil and chemical industry.

The heat exchange equipment can be divided into three kinds 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 exchanger structure is simple, but cheap, often made of tower. Two kinds of media, which allow for complete mixing and different temperatures, complete the heat transfer in the process of direct contact. For example: cold water tower (cooling tower), prilling tower, air drying device, fluidized bed, etc..

2 regenerative heat exchanger

In this type of heat exchanger, the energy transfer is accomplished by means of a stack of tiles or fillers. First, let the hot fluid pass through, heat the heat in the regenerator, and then let the cold fluid pass through the heat. Because of the alternation of the two fluids, it is inevitable that there is a small amount of fluid mixing with each other".

The regenerative heat exchanger has the advantages of compact structure, low cost and large heat transfer surface per unit volume, so it is more suitable for gas - gas heat exchange. Mainly used in the production of petrochemical raw material gas conversion and air waste heat. Rotary regenerative heat exchanger structure is to realize continuous operation, in general the fan-shaped cabinet molding plate or metal mesh assembly in regenerative heat exchanger, the outer seal consists of a metal shell, and to every 1 ~ 4 turn slowly rotating continuous heat transfer.

3, wall type heat exchanger

The so-called wall type heat exchanger, refers to the two different temperatures of fluid in a fixed wall (called the heat transfer surface) separated by the flow of space, through the surface of the heat conduction and the surface of the convective heat transfer. The heat transfer fluid is not mixed and the transfer process is continuous and stable. The heat transfer surface of the heat exchanger is mostly made of metal with good thermal conductivity. In some occasions because of the need for corrosion resistance, but also the use of non-metallic (such as graphite, poly four ethylene, etc.). This is one of the most widely used types of heat exchangers. The cold and hot fluid is separated by a solid wall.

According to the shape and structure of heat transfer surface, it can be divided into:

(1) tubular heat exchanger: such as casing type, spiral tube type, shell type, heat pipe type, etc..

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

(3) extended surface heat exchanger, such as plate fin, tube fin, heat transfer tube, etc..