As a kind of heat exchange equipment, plate heat exchanger has been widely used in many fields in our country and has brought great economic benefits. However, various failures and damages of plate heat exchangers also cause certain economic losses to users. The reasons are various. It is related to the short application history of plate heat exchangers in our country and insufficient experience in design, use, maintenance and maintenance.
1. seal failure
1.1 pressure When the detachable plate heat exchanger is used within the rated working pressure, leakage occurs, which is mainly related to abnormal impact load (water hammer and air hammer) in the system besides the quality factors of equipment in manufacturing and assembly. This is a phenomenon that is not easy to be observed by ordinary operators. The instantaneous pressure peak caused by impact is usually 1-3 times higher than the normal working pressure, which causes the rubber gasket installed in the plate heat exchanger to shift, leading to seal failure. As the heat transfer element of this equipment is made of stainless steel sheet (thickness is 0.5-0.8), its sealing rigidity is relatively poor and its sealing periphery is very long, so its impact pressure resistance is much lower than that of shell-and-tube heat exchanger. Precautions: ① Considering the structural characteristics of the plate heat exchanger and depending on the operating pressure, increase the design pressure of the equipment by 1.5-2 times. (2) The impact phenomenon in the system should be avoided as much as possible during use. (3) In applications where such accidents have occurred, measures can be taken to increase the plate thickness depending on the situation, with obvious effect.
1.2 Temperature Rapid changes in temperature can also cause seal failure. When the temperature changes too fast, the linear expansion coefficient of the rubber gasket does not match the elastic deformation and the sealing pre-tightening force, which reduces the sealing pre-tightening force and causes the bearing capacity of the equipment to be lower than the rated design pressure. The following methods can be adopted to solve this problem: ① The pressure rise and temperature rise should be slowed down as much as possible when operating the equipment. (2) A compression pre-tightening spring can be designed on the clamping stud to effectively compensate the change of the sealing pre-tightening force and prevent leakage.