A heat exchanger is a device that transfers part of the heat of a hot fluid to a cold fluid, also known as a heat exchanger. Heat exchangers play an important role in chemical, petroleum, power, food and many other industrial production. They can be used as heaters, coolers, condensers, evaporators and reboilers in chemical production, and are widely used.

Heat exchanger is a kind of energy-saving equipment which can transfer heat between two or more fluids at different temperatures. It is used to transfer heat from high-temperature fluids to low-temperature fluids, so that the temperature of fluids can meet the requirement of the process, and at the same time, it can improve the energy utilization rate. One of the main equipment. Heat exchanger industry involves HVAC, pressure vessels, water treatment equipment, chemical, petroleum and other nearly 30 kinds of industries, forming an industrial chain each other. The data show that the market of heat exchanger industry in China in 2010 is about 50 billion yuan, mainly concentrated in petroleum, chemical industry, metallurgy, electricity, ships, central heating, refrigeration and air conditioning, machinery, food, pharmaceutical and other fields. Among them, petrochemical industry is still the largest market of heat exchanger industry, with a market size of 15 billion yuan, electric power and metallurgy market size of 8 billion yuan, ship industry heat exchanger market size of more than 4 billion yuan, machinery industry heat exchanger market size of about 4 billion yuan, central heating industry heat exchanger Market Regulations The mold is over 3 billion yuan, and the food industry has a market of nearly 3 billion yuan. In addition, a large number of specialized heat exchangers are needed in the fields of spacecraft, semiconductor devices, nuclear power island, wind turbine, solar photovoltaic power generation, polysilicon production and so on. These markets are about 13 billion yuan in size. The domestic heat exchanger industry has made remarkable achievements in energy saving, heat transfer efficiency improvement, heat transfer area reduction, pressure drop reduction and heat intensity improvement. Based on the steady growth of demand for heat exchangers in petroleum, chemical industry, electric power, metallurgy, shipping, machinery, food, pharmaceutical and other industries, China's heat exchanger industry will maintain a steady growth in the coming period. From 2011 to 2020, China's heat exchanger industry will maintain an average annual growth rate of about 10-15%, until 2020. The scale of the heat exchanger industry is expected to reach 150 billion yuan.

It is suitable for heat exchangers with different media, different working conditions, different temperatures and different pressures. The structure types are also different. The specific classification of heat exchangers is as follows:

Classification according to heat transfer principle

1. The wall-to-wall heat exchanger is a kind of two kinds of fluids with different temperatures flowing in the space separated by the wall. Heat conduction and convection are carried out between the two kinds of fluids. The wall type heat exchanger has shell and tube type, sleeve type and other types of heat exchangers. The wall type heat exchanger is the most widely used heat exchanger at present.

2. The regenerative heat exchanger of regenerative heat exchanger transfers heat from high-temperature fluid to low-temperature fluid through the regenerator made up of solid material. After the heat medium reaches a certain temperature by heating the solid material, the cold medium is heated through the solid material to achieve the purpose of heat transfer. The regenerative heat exchanger has rotary type and valve switching mode.

3. Fluid Connected Indirect Heat Exchanger Fluid Connected Indirect Heat Exchanger is a kind of heat exchanger which connects two surface heat exchangers by the heat carrier circulating in it. The heat carrier circulates between the high temperature fluid heat exchanger and the low temperature fluid, accepts the heat in the high temperature fluid, and releases the heat to the low temperature fluid heat exchanger. Body.

4. The direct contact heat exchanger is also called the mixed heat exchanger. This kind of heat exchanger is the equipment that two kinds of fluids contact directly and mix with each other for heat transfer, such as cold water tower, gas condenser and so on.

5. Compound heat exchanger has two kinds of heat exchangers: steam-water surface indirect heat transfer and water-water direct mixed flow heat transfer. Compared with steam-water surface indirect heat transfer, it has higher heat transfer efficiency, higher stability and lower unit noise compared with steam-water direct mixing heat transfer.

Two. Classification by use

1. The heater is to heat the fluid to the necessary temperature, but there is no phase change in the heated fluid.

2, preheater preheater heating the fluid in advance, to provide standard process parameters for process operation.

3. Superheater superheater is used to heat fluid (process gas or steam) to overheat.

4. The evaporator evaporator is used to heat the fluid to a temperature above the boiling point, so that the fluid evaporates, generally there is a phase change.

Three. Classification by structure

It can be divided into floating head heat exchanger, fixed tube-plate heat exchanger, U-tube-plate heat exchanger, plate heat exchanger and so on.

Matters needing attention

1, keep the pipeline clean. Both before and after work, the pipe network must be cleaned to avoid the phenomenon of heat exchanger blockage. We should also pay attention to cleaning the cleaner and filter in time, so that the whole work can be successfully completed.

2, strictly check the softened water. It is very important to check the water quality. On the premise of softening water quality treatment, the water quality of the system and softening tank should be carefully checked before injection treatment can be carried out.

3. New system test. For some new systems, the heat exchanger can not be used alternately immediately. First, the new system needs to run in a specified period of time, so that it has a mode of operation, then the heat exchanger can be incorporated into the system. The purpose of doing so is to avoid the impurities in the pipe network destroying the heat exchanger equipment.