Shell and tube heat exchanger which is also known as tube heat exchanger is closed in the shell tube wall surface as the heat transfer surface of the wall heat exchanger. Shell and tube heat exchanger from the shell, heat pipe bundle, tube board, baffle (baffle) and tube boxes and other components. Shell is mostly cylindrical, equipped with a tube bundle inside, the tube bundle ends fixed on the tube plate. The two fluids, hot and cold, that heat the tube, one that flows in the tube and is called the tube-path fluid and the other that flows outside the tube, is called the shell-side fluid.
In order to increase the heat transfer coefficient of the fluid outside the tube, several baffles are usually installed in the housing. The baffle can increase the velocity of the shell-side fluid and force the fluid to cross the tube bundle several times over the prescribed distance to enhance the turbulence of the fluid.
This heat exchanger has the simple structure and is low cost, wide circulation cross-section, easy to clean scale, can be used under high temperature and pressure. It is widely used in petroleum, chemical, metallurgy, electric power, medicine, food, energy and HVAC industries. It is the most widely used type. The common types of the shell and tube heat exchanger include fixed tube plate, floating head, fill function and U-tube.
|Shell and tube heat exchanger||Shell, tube bundle, baffle, tube plate, tube box, head and other components.|
|Cylinder material||Carbon steel, stainless steel|
|Tube material||Carbon steel, stainless steel, copper, titanium|
|Design pressure||Less than 35MPa|
|Design temperature||Up to 450 degrees|
|Cylinder diameter||Up to 4000mm|
|Standard||GB150, GB151, ASME|
1.Fixed tube heat exchanger
Fixed tube plate heat exchanger is divided into a rigid structure of the fixed tube plate and fixed tube plate with expansion joints. The heat exchanger housing and tube bundle are rigidly connected together by tube plates at both ends.
Advantages: The heat exchanger structure is simple, low cost, each tube can be individually replaced, the tube is easy to clean.
Disadvantages: Difficult to clean outside the tube, there is temperature stress between the shell and tube. When the temperature difference between the two media is larger, expansion joints must be set.
Fixed tube plate heat exchanger for shell-side media cleaning, scaling, temperature difference is not large and shell-side pressure is not high occasions.
2.Floating head heat exchanger
Only one tube plate in the floating head heat exchanger is rigidly attached to the shell, and the tube plate on the other end is free to move within the shell. Tube bundles and shells expand freely at different temperatures without mutual involvement.
Advantages: This heat exchanger eliminates the effects of temperature stress, can be used for heat transfer of two media with larger temperature difference. Pipe and shell can withstand higher media pressure. The tube bundle can be drawn out from one end of the shell shell, and the cleaning of the shell shell and the tube shell is very convenient.
Disadvantages: Due to the larger annulus between the heat exchanger tubes and the shell side, the equipment is less compact and the heat transfer efficiency is lower. The structure is complex. The floating head consists of movable tube plate, floating head cover and hooking ring. The internal leakage of floating head is inconvenient. Metal consumption, high cost.
3.Fill function heat exchanger
Fill-type heat exchanger floating head and shell filled with stuffing box for sealing and thermal compensation. In order to reduce the annular gap between the tube bundle and the housing, a sliding tube plate structure can be adopted.
Advantages: simple structure, lower cost than Float. Overhaul, easy to clean, fill the leak at the leak can be found in time.
Disadvantages: the shell side by the packing seal restrictions, can not withstand excessive pressure and temperature. And there is a possibility of leakage in the shell-side medium, which is not suitable for dealing with volatile, flammable, explosive and poisonous medium in the shell-side.
4.U-tube heat exchanger
Heat exchanger tube bundle bent into U-shaped, U-tube ends fixed in the same tube plate, plus a separator in the tube box.
Advantages: only a heat exchanger tube plate, simple structure, low cost. Tube bundle can be extracted and cleaned, the tube can be freely expanded.
Disadvantages: inconvenient to wash the tube, tube plate less tube, the structure is not compact. Foreign media easy to short circuit, affecting the heat transfer effect. Inner tube damage is not easy to replace.
U-tube heat exchanger is mainly used for cleaning the tube without scaling high temperature, high pressure medium. Strong adaptability of the shell medium, commonly used in high pressure, high temperature, viscosity larger occasions.