Stage Heat Exchangers for Process Compressors

One, two or three Stage Heat Exchangers for Process Compressors

In industrial processes, compressors often require primary, secondary and tertiary heat exchangers to ensure the efficient operation of the system. These heat exchangers provide cooling and heat recovery at different stages of the compressed air process in order to reduce temperatures, improve efficiency and protect the compressor and subsequent equipment.

Role and working principle of primary, secondary and tertiary heat exchangers:

First-stage heat exchanger (aftercooler/intercooler):

Location: usually installed in the compressor exhaust end or after the first compression stage.

Function: The main function of the first stage heat exchanger is to initially cool the high temperature compressed air, usually using air or water as the cooling medium. The cooled air temperature is reduced to prevent overheating, and at the same time, a portion of the water vapour can be condensed to reduce the burden of subsequent condensate treatment.

Principle of operation: high-temperature compressed air flows through the pipe of the cooler, the heat is transferred to the flowing cooling medium through the pipe wall, and the air temperature is significantly reduced.

Secondary heat exchanger (intercooler)

Location: Installed in the compressor between the first and second stage compression, or multi-stage compression between any two stages.

Function: The secondary heat exchanger is used to further cool the air, after the first stage of compression, to a temperature suitable for entering the next stage of the compressor. This process not only improves overall compression efficiency, but also reduces compressor wear and energy loss due to high temperatures.

Principle of operation: The compressed air is cooled again by the cooling medium as it passes through the secondary heat exchanger, usually by means of an air-to-air or air-to-water heat exchange, which further reduces the temperature and discharges the condensate.

Three-stage heat exchanger (aftercooler)

Location: Located after the final discharge end of the compressor and before entering the storage tank or process equipment.

Function: The function of the three-stage heat exchanger is to provide final cooling of the final compressed air. The cooled air is easier to store, the reduced temperature prevents overheating of downstream equipment and helps to further remove residual water vapour and oil.

Principle of operation: As the compressed air passes through the three-stage heat exchanger, it again exchanges heat with the cooling medium, ultimately lowering the temperature to the level required by the process and further separating out the water vapour.

Considerations when selecting and designing a heat exchanger:

Cooling medium: the choice of suitable cooling medium (such as water, air or oil) is the key to the design, need to consider the supply of media, cost and effectiveness.

Heat exchanger material: copper, aluminium or stainless steel are commonly used materials, selection should be considered corrosion resistance, thermal conductivity and system operating temperature.

Pressure and temperature requirements: heat exchanger must be able to withstand the system's highest operating pressure and temperature, while ensuring long-term stable operation.

Efficiency and energy saving: heat exchanger design should be as much as possible to improve the heat exchange efficiency, reduce pressure drop and energy loss.

Maintenance and cleaning: the design should take into account the maintainability of the heat exchanger, easy to clean and maintain, in order to extend the service life.

Summary:

In the compression process, primary, secondary and tertiary heat exchangers effectively control the temperature of the compressed air through multi-stage cooling to improve compression efficiency and protect the equipment, as well as to meet the temperature requirements of the downstream process. The use of appropriate materials and design can ensure efficient and long-term reliable operation of the system.