Material and performance evaluation of plate heat exchanger gasket_
Material and performance evaluation of gaskets for plate heat exchangers
891 plate heat exchanger sealing gasket is a key part of the plate heat exchanger. The working temperature of the plate heat exchanger is essentially the temperature that the gasket can withstand, and the working pressure of the plate heat exchanger is also restricted by the gasket. The weaker part of the plate heat exchanger is the plate heat exchanger gasket. Over the years, it has been the focus of public attention and exploration, and some progress has been made in temperature and corrosion resistance materials and their performance evaluation. (1) Nitrile rubber (NBR) is generally suitable for working conditions below 120 ℃. The newly developed high-temperature NBR can reach 145 ℃, and the hydrogenated NBR can reach 160 ℃; EPDM was only used for 150 in the past. ℃, the high temperature EPDM has increased to 160 ℃; Fluoro-propylene rubber (FPM) can be used at 175 ℃; the applicable temperature of graphite laminated gasket can reach 400 ℃, which can well replace compressed asbestos fiber gaskets. (2) Coated gaskets use general rubber or metal blocks as the core, and are coated with polytetrafluoroethylene (PTFE) or fluorinated synthetic materials, etc., which can be used for highly corrosive media or increase the temperature limit. HISAKA is the first to use PTFE-coated NBR gaskets, which greatly expands the application areas of PHE and extends the service life of gaskets. ALFA-LAVAL has used this gasket for double plate welding PHE. (3) With the development of non-adhesive gaskets, the formulation of materials for non-adhesive gaskets must be slightly changed, requiring more stable performance, more durability and better tear resistance. (4) To evaluate the temperature resistance of gaskets, there are two main indicators: compression set and hardness at rated temperature. For new gasket materials, generally the ring sample test and the overall test of the plate and the gasket are required, and the test time is 5-40 days. The recommended use temperature limit of gaskets should be lower than the compression set curve after considering a certain safety factor. The quality and service life of the plate heat exchanger largely depend on the quality and service life of the gasket. For large logarithmic heat exchangers, the plates are generally not damaged, and the gasket is prone to ageing and cause leakage. Therefore, the quality of the gasket determines the quality and service life of the heat exchanger.