What is shell and tube heat exchanger

What is shell and tube heat exchanger

Shell and tube heat exchanger is also called tubular heat exchanger. It is an inter wall heat exchanger with the wall surface of the tube bundle enclosed in the shell as the heat transfer surface.

The heat exchanger has the advantages of simple structure, low cost, wide flow section and easy to clean scale; However, the heat transfer coefficient is low and the floor area is large.

It can be made of various structural materials (mainly metal materials) and can be used under high temperature and high pressure. It is a widely used type at present

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shell and tube heat exchanger structure

Shell and tube heat exchanger is composed of shell, heat transfer tube bundle, tubesheet, baffle (baffle) and tube box.

The shell is mostly cylindrical, with a tube bundle inside, and both ends of the tube bundle are fixed on the tube plate. There are two kinds of cold and hot fluids for heat exchange.

One flows in the pipe, which is called pipe side fluid; The other one flows outside the tube, which is called shell side fluid. In order to improve the heat transfer coefficient of the fluid outside the tube,

several baffles are usually installed in the shell.

The baffle can increase the fluid velocity on the shell side, force the fluid to cross the tube bundle several times according to the specified distance, and enhance the degree of fluid turbulence.
The heat exchange tubes can be arranged in equilateral triangles or squares on the tube sheet.

The equilateral triangle arrangement is compact, the degree of fluid turbulence outside the tube is high, and the heat transfer coefficient is large; Square arrangement is convenient for cleaning outside the pipe, which is suitable for fluids easy to scale.

The main control parameters of shell and tube heat exchanger are heating area, hot water flow, heat exchange, heat medium parameters, etc.

Each time the fluid passes through the tube bundle is called a tube side; Each pass through the shell is called a shell pass. The figure shows a simple single shell side and single tube side heat exchanger, which is referred to as type 1-1 heat exchanger for short.

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In order to improve the fluid velocity in the pipe, diaphragms can be set in the pipe boxes at both ends to divide all pipes into several groups. In this way, the fluid only passes through part of the tube at a time, so it goes back and forth many times in the tube bundle, which is called multi tube pass.

In order to improve the flow rate outside the pipe, a longitudinal baffle can also be installed in the shell to force the fluid to pass through the shell space for many times,

which is called multi shell side. Multi tube pass and multi shell pass can be used together.

shell and tube heat exchanger characteristic

1. High efficiency and energy saving. The heat transfer coefficient of the heat exchanger is 6000-8000W / m2 0C。

2. It is made of all stainless steel and has a long service life of more than 20 years.

3. Changing laminar flow to turbulence improves heat exchange efficiency and reduces thermal resistance.

4. Fast heat exchange, high temperature resistance (400 ℃) and high pressure resistance (2.5MPa).

5. Compact structure, small floor area, light weight, convenient installation and saving civil engineering investment

6. Flexible design, complete specifications, strong practicability and pertinence, and save money.

7. Wide application conditions, applicable to large pressure, temperature range and heat exchange of various media.

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8. Low maintenance cost, easy operation, long cleaning cycle and convenient cleaning.

9. Nano hot film technology is adopted to significantly increase the heat transfer coefficient.

10. It has a wide range of applications and can be widely used in thermal power, factories and mines, petrochemical industry, urban central heating, food and medicine, energy electronics, machinery, light industry and other fields.

11. The heat transfer tube adopts copper tube with rolled fins on the outer surface, which has high thermal conductivity and large heat exchange area.

12. The deflector guides the shell side fluid to flow continuously in a broken line shape in the heat exchanger. The spacing of the deflector can be adjusted according to the flow rate.

The structure is solid and can meet the heat exchange of shell side fluid with large flow or even super large flow and high pulsation frequency.

13. When the shell side fluid is oil, it is suitable for oil heat exchange with low viscosity and cleaner oil.