Shell and Tube Low Temperature Heat Exchanger
Shell and tube low-temperature heat exchanger is mainly composed of shell, tube bundle, tube plate, header, baffle and other components. Shell is a cylindrical structure, used to accommodate the tube bundle; tube bundle consists of a number of straight tubes or U-shaped tubes, is the main place of heat exchange; tube plate connects the tube bundle with the shell to withstand the fluid pressure and thermal stress; header is located at the ends of the shell, used to close the shell and distribution, collection of fluid; baffle plate to guide the shell process fluid several times through the bundle laterally, to enhance turbulence effect, enhance the efficiency of heat transfer.
Working Principle: Heat transfer is carried out by utilizing two fluids with different temperatures in the tube and shell processes. Low-temperature fluid flows in the tube bundle, high-temperature fluid flows in the shell space outside the tube bundle, and heat is transferred from the high-temperature fluid to the low-temperature fluid through the tube wall to realize heat exchange. Heat transfer efficiency can be improved through rational design of flow paths and selection of fluid flow methods, such as countercurrent arrangement.
Advantages
Rugged structure: able to withstand high pressure and low temperature environment, suitable for a variety of harsh working conditions.
Strong adaptability: can deal with a variety of different properties of the fluid, including corrosive fluids, as long as the choice of appropriate materials, can ensure the normal operation of the heat exchanger.
High heat transfer efficiency: through the installation of baffles, the use of countercurrent flow and other ways, as well as the rational design of the tube bundle arrangement and shell and tube structure, can achieve efficient heat exchange.
Easy maintenance: some types of shell and tube low-temperature heat exchangers, such as floating head type and U-tube type, the tube bundles can be withdrawn, which is convenient for cleaning and repairing the internal components.
Disadvantages
Large size: Shell and tube cryogenic heat exchangers are larger and heavier and take up more space than some compact heat exchangers.
Thermal stress problem: Under low temperature working conditions, the temperature difference between the tube bundle and the shell may lead to thermal stress, and corresponding measures, such as setting expansion joints and adopting suitable structural forms, need to be taken to solve the thermal stress problem, or the service life and performance of the heat exchanger may be affected.
Higher resistance loss: When the fluid flows in the tube and shell processes, due to the complexity of the flow path and the friction between the fluid and the tube wall, baffle plate, etc., a higher resistance loss will be generated, which increases the energy consumption of fluid transportation.
Field of application
Natural gas liquefaction: Used in the pre-cooling, liquefaction and sub-cooling phases of the LNG (liquefied natural gas) production process to cool the natural gas to a low temperature for liquefaction. Highly efficient heat transfer performance helps to reduce energy consumption and improve liquefaction efficiency.
Cryogenic refrigeration: It can realize the ultra-low temperature working condition of - 80℃ or even lower, and is applied in the fields of biological sample bank, superconductivity experiment, etc., providing a low temperature environment for the relevant experiments and production processes.
Air Separation: Used in air separation devices to cool, liquefy and separate air to produce oxygen, nitrogen, argon and other gas products.
Chemical industry: It is used for heat exchange in the process of low-temperature chemical reaction, controlling the reaction temperature, improving the reaction efficiency and product quality, and also used for heating of low-temperature fluid or cooling of high-temperature fluid, as well as distillation of organic solvents, crystallization and other processes.
