Common heat exchangers are divided into three types: jacket heat exchangers, tube heat exchangers, and plate heat exchangers. Among them, tube heat exchangers are divided into column tube heat exchangers, coil tube heat exchangers, sleeve tube heat exchangers, etc; Plate heat exchangers are usually divided into plate heat exchangers, spiral plate heat exchangers, etc.
1、 Jacketed heat exchanger
A jacket type heat exchanger is a heat exchange device that adds a jacket to a container or tube, forming a closed space inside the jacket and adding a heat exchange medium. When steam is heated, steam enters from the top; When condensing, the condensate enters from the bottom.
This type of heat exchanger has a simple structure, small footprint, and low price. But the heat transfer efficiency is low and difficult to clean, only used in situations where the heat transfer load is not high and the heat transfer medium is clean.
2、 Tubular heat exchanger
A tubular heat exchanger, also known as a shell and tube heat exchanger, is mainly composed of an outer shell, tube sheets, tube bundles, and heads. The working principle of a tubular heat exchanger is that one fluid enters the tube through the head connecting pipe, while the other fluid flows between the tubes inside the shell. The surface area of the tube bundle is the heat exchange area. The flow velocity, heat transfer area, and material of the tube bundle have an impact on the heat transfer efficiency of a tubular heat exchanger. The heat transfer efficiency of tubular heat exchangers can be improved by adding baffles, baffles, thermal compensation, and other methods.
The material channel inside the tube is usually referred to as the tube side, and the material channels inside and outside the shell are referred to as the shell side. Both the tube side and the shell side can be divided into single or multiple paths. According to this, tubular heat exchangers can be divided into: single pass tube side and multi pass shell side; Multi pass management and single pass shell process; Both the tube and shell processes are multi pass, etc.
3、 Spiral plate heat exchanger
Spiral plate heat exchanger is composed of two relatively slender metal plates welded with fixed distance tubes, wound around a spiral axis, forming a spiral channel for two fluids.
The basic spiral shaped components can be sealed by welding on both sides of the channel, or sealed with end caps and packing, which can make two fluids flow in a spiral counter current, or make one fluid flow in a spiral, and the other fluid flow laterally or in combination with the spiral. The entire assembly of parts is enclosed in a cylindrical shell.
Spiral plate heat exchangers have a high heat transfer coefficient, which is about 20% higher than that of shell and tube heat exchangers under the same conditions; It is easier to handle viscous and scaled liquids and slurries, and the scaling rate is lower than that of shell and tube heat exchangers; Compact structure, no need for pipes, and less ineffective internal volume. However, the size and operating pressure are subject to certain limitations, resulting in high resistance and difficulty in maintenance and cleaning.
