Double tube plate heat exchanger is mainly used for high temperature, high pressure, flammable, explosive, toxic or strong corrosive medium under the working conditions, if it is to be better promoted and applied, it is necessary to master the design, manufacturing, In each link of operation and maintenance, it is very important that the double-tube sheet converter is of good manufacturing quality and requires higher manufacturing accuracy. At the same time, the quality of the heat exchange tube must be good to ensure that the heat exchange tube wall does not crack during use.
1. Precautions for the use of double tube plate heat exchanger
① When the two media in the tube side and the shell side are mixed, it will cause severe corrosion;
②The infiltration of extremely or highly hazardous media on one side to the other side will cause serious consequences;
③When the tube side and shell side media are mixed, the two media will cause combustion or explosion;
④ When one medium is mixed with another medium, it will cause catalyst poisoning;
⑤The mixing of the tube side and shell side media will cause polymerization or produce resin-like substances;
⑥After the tube side and shell side media are mixed, the chemical reaction will be terminated or restricted;
⑦After the tube side and shell side media are mixed, it will cause product pollution or product quality degradation.
2. The structure of the double tube plate heat exchanger
The double tube sheet heat exchanger adopts a fixed tube sheet structure, and the tube bundle cannot be extracted for cleaning. This is different from the single tube sheet heat exchanger which can adopt a variety of structural types and the tube bundle can be extracted for cleaning. For double-tube sheet heat exchangers with large temperature differences, corrugated expansion joints can be installed on the cylinder; while for single-tube sheet heat exchangers, in addition to installing corrugated expansion joints on the cylinder, floating heads or U-shaped tube types are often used. To compensate. For the double tube plate heat exchanger, there are two design concepts: one thinks that the double tube plate heat exchanger is used to absolutely prevent the mixing of the medium between the tube and the shell side, and it is designed to install on the cavity between the inner and outer tube sheets. The drain valve is used for daily observation and discharge when the inner tube sheet leaks, so that the shell side medium is effectively separated by the inner and outer tube sheets. This is the main purpose of adopting the double tube plate structure. The other is that the double tube sheet heat exchanger can be used in occasions where the medium pressure difference between the tube and shell side is large. It is designed to add a medium to the cavity between the inner and outer tube sheets to reduce the pressure of the medium between the tube and shell sides. Difference. This is the same as a general single tube sheet heat exchanger, and it cannot be absolutely guaranteed that there will be no leakage at the nozzles of the outer tube sheet. The isolation cavity between the double tube sheet is the main difference from the structure of the single tube sheet heat exchanger. The isolation cavity is not connected with the tube side and the shell side, and does not bear the pressure of the medium, but bears the mechanical load and thermal load of the equipment. The load-bearing capacity of the isolation cavity mainly depends on the distance between the double tube sheets. When performing a shell-side hydraulic test on a fixed double tube sheet, there may be leakage at the connection between the inner tube sheet and the heat exchange tube. Therefore, the minimum space required for observation and leak detection must be considered when determining the distance between the double tube sheet.