Views:1 Author:Site Editor Publish Time: 2020-10-22 Origin:Site
The fixed tube sheet heat exchanger is composed of tube sheets at both ends and a shell. Because of its simple structure, it is widely used.
Fixed tube-sheet heat exchanger is an energy-saving equipment that realizes heat transfer between materials. It is a process equipment commonly used in petroleum, chemical, petrochemical, metallurgy, electric power, light industry, food and other industries. In oil refining and chemical plants, heat exchangers account for about 40% of the total equipment, and 30%-45% of the total investment. With the development of energy-saving technologies and the continuous expansion of application areas, the use of heat exchangers for high and low temperature heat energy recovery has brought significant economic benefits.
In the tube side and shell side of the fixed tube-sheet heat exchanger, fluids of different temperatures flow through, and heat exchange is completed through heat exchange. When the temperature difference between the two fluids is large, in order to avoid high temperature difference stress, a compensation ring (expansion joint) is usually added at an appropriate position on the shell side. When the thermal expansion of the shell and the tube bundle are different, the compensation ring undergoes slow elastic deformation to compensate for the thermal expansion caused by the temperature difference stress.
The fixed tube-sheet heat exchanger is composed of tube box, shell, tube sheet, tube and other parts. It has a compact structure, many rows of tubes, a larger area under the same diameter, and simple manufacturing.
The structural feature of the fixed tube sheet heat exchanger is that the tube bundle is arranged in the shell. The tube bundle is fixed on the tube plate by welding or expansion method at both ends. The tube plate at both ends is directly welded to the shell. The inlet and outlet pipes are directly welded to the shell. The outer circumference of the tube plate and the head flange are fastened by bolts. The inlet and outlet pipes of the tube pass are directly welded to the head. Several heat exchange tubes are set in the tube bundle. Block baffles. The tube pass of this heat exchanger can be divided into any number of passes with a partition.
The fixed tube-plate heat exchanger has simple structure, low manufacturing cost, and easy cleaning of the tube pass. The tube pass can be divided into multiple passes and the shell pass can also be divided into double passes. It has a wide range of specifications and is widely used in engineering. It is difficult to clean the shell side, so it is not suitable for dirty or corrosive media. When the expansion difference is large, an expansion joint can be provided on the shell to reduce the thermal stress caused by the temperature difference between the tube and the shell side.
The characteristics of the fixed tube plate heat exchanger are:
1. The bypass seepage is small;
2. Forgings are used less, and the cost is low;
3. No internal leakage;
4. The heat transfer area is 20% to 30% larger than that of the floating head heat exchanger.
The disadvantages of fixed tube plate heat exchanger are:
1. The temperature difference between the shell and the pipe wall is large, when t≥50℃, an expansion joint must be installed on the shell;
2. It is easy to produce temperature difference force, and it is easy to produce temperature difference stress between tube sheet and tube head and damage;
3. The shell side cannot be cleaned mechanically;
4. After the pipe is corroded, the shell is scrapped, and the equipment life is relatively low.
In addition to the most critical heat exchange plate, the mechanical design of the fixed tube plate heat exchanger also has two wall plates, which we call the frame plate and the pressure plate. The frame plate is the outer wall and the pressure plate is heat exchange. The wall panel on the other side of the plate can be adjusted by tie rod bolts; several tie rod bolts are used to tighten the frame plate and the pressure plate; the column; the upper and lower guide rods are connected between the frame plate and the column to support and give pressure The plate and the heat exchange half piece are guided; the frame plate and the column can be installed with feet and feet to fix the machine. In addition, there can also be a series of accessories such as flanges, filters, thermometers and pressure gauges.