Shell and tube heat exchangers, also known as tubular heat exchangers, are a type of equipment that uses a tube bundle enclosed in a cylindrical shell for heat exchange. Shell-and-tube heat exchanger is a kind of equipment widely used in industrial process for heat exchange, it is suitable for high temperature, high pressure working environment, can handle the heat exchange needs of various fluids.

Shell and tube heat exchanger composition

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

Shell: usually cylindrical, is the external structure of the heat exchanger, and the heat transfer tube bundle is contained inside.

Heat transfer tube bundle: located inside the shell, both ends are fixed on the tube plate, is the main place to achieve heat exchange.

Tube plate: located at both ends of the housing, it is used to hold the heat transfer tube bundle and form a seal with it to ensure that the two fluids do not mix.

Baffle (baffle) : installed in the shell, used to guide the shell side fluid through the tube bundle several times, increase the degree of fluid turbulence, improve the heat transfer efficiency.

Tube box: Located at both ends of the heat exchanger and connected to the tube plate, it is used to distribute and collect the pipe flow.

Characteristics of shell-and-tube heat exchanger

The advantages of shell-and-tube heat exchangers mainly include:

High heat transfer coefficient: The threaded tube used in shell and tube heat exchangers is made of materials with high thermal conductivity, such as copper or stainless steel, and the design of the combination of internal and external threads can form strong turbulence under little fluid resistance, thus greatly improving the heat transfer coefficient inside and outside the tube.

Compact structure: Because the unit volume heat transfer area of the shell and tube heat exchanger is large, the total heat transfer coefficient is high, so the floor area is small, saving materials and space.

Not easy to scale: The special concave and convex structure of the threaded pipe and the hot extension and cold shrinkage of the pipe make it difficult to retain impurities inside and outside the pipe, so it is not easy to scale, to ensure the long-term operation effect.

Not easy to leak: the sealing circumference of the shell and tube heat exchanger, and the coarse thread of the threaded pipe has a compensation capacity similar to the expansion joint, making the thermal stress of the heat exchanger small and not easy to leak.

Strong applicability: According to different process requirements, there are many types of shell and tube heat exchangers, such as fixed tube plate, floating head type, U-shaped tube type, etc., each has its own characteristics and scope of application, which can meet the needs of different working conditions.

Easy maintenance: Some types of shell and tube heat exchangers are designed to allow tube bundles to be drawn from the shell for easy cleaning and maintenance, especially for media that are prone to scaling or require frequent cleaning.

Shell and tube heat exchanger application field

Chemical industry: In the chemical reaction process, it is often necessary to heat or cool raw materials or products, and shell and tube heat exchangers play an important role here.

Oil and gas industry: These industries often need to exchange heat for oil and gas during the refining process, and shell and tube heat exchangers can withstand the high temperatures and pressures in these processes.

Food industry: In the process of food processing, shell and tube heat exchangers are used for heating, cooling and pasteurization to ensure the safety and quality of food.

Power industry: In power plants, shell-and-tube heat exchangers are used for the generation and condensation of steam and are key equipment for the normal operation of power stations.

Metallurgical industry: In the process of metal processing, shell-and-tube heat exchangers are used for temperature control of heat treatment furnaces and for cooling metal products.

Hvac industry: In heating and air conditioning systems, shell-and-tube heat exchangers are used for heating and cooling hot water to keep the indoor temperature comfortable.

The technical principle of shell and tube heat exchanger is mainly based on wall heat transfer, in which a fluid flows inside the tube bundle, and another fluid flows in the shell outside the tube bundle, and the two exchange heat through the tube wall. Specifically, the working principle of shell and tube heat exchanger includes the following aspects:

Heat transfer surface: the wall of the tube bundle is used as a heat transfer surface, and two kinds of working fluids flow inside and outside the tube respectively, and heat exchange through the tube wall.

Fluid flow: pipe flow in the tube, shell flow outside the tube. In order to improve the heat transfer efficiency of the pipeline fluid, some designs use spiral tubes or nodule tubes, which can increase the degree of turbulence of the fluid, thereby improving the heat transfer coefficient.

Temperature control: By adjusting the heat source flow into the heat exchanger, the temperature of the heated medium can be controlled. For example, there is a regulating valve before the heat source inlet, and changing the valve opening can adjust the outlet temperature.

The design and manufacture of shell-and-tube heat exchangers is a complex process that requires comprehensive consideration of many factors, including process requirements, material selection, structural design, safety standards, etc.

Check the heat transfer coefficient and heat transfer area: Calculate the heat transfer coefficient K and heat transfer area F according to the heat transfer coefficient of pipe and shell, dirt thermal resistance, wall thermal resistance, etc. This step takes into account a number of factors, such as differences between operating conditions and design conditions, and possible future scaling or clogging problems.

Manufacturing technology: The manufacturing process of shell and tube heat exchanger includes selecting the appropriate material, determining the specifications and arrangement of the tube bundle, and the number of baffle or support plate. These manufacturing details are critical to the performance and durability of heat exchangers.

Design conditions: Users need to provide some key design conditions, such as operating pressure, operating temperature, metal wall temperature, material name and characteristics, corrosion margin, number of passes, heat exchange area, heat exchange tube specifications, etc. This information is essential for the design of an efficient and safe heat exchanger.

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