Coloration method: check with colorant; 2. Light transmission method: a light source is placed on one side of the plate, and people check on the other side; 3. Unilateral pressure test method: one side through the water pressure test to 0.35Mpa (gauge pressure), if there is water at the lowest part of the other side, quickly check the wet part of the plate. We choose the light transmission method for inspection. The advantages of this method are convenience and low cost. It is suitable for the inspection of new and old plates. But the responsibility of maintenance personnel is required to be high. According to the inspection of plates, there are three ways to determine the workload: 1. Replace all plates and gaskets; 2. Only replace the washer; 3. Replace the washer and some damaged and deformed plates. 4、 Apply a layer of adhesive or strong adhesive to the bottom of the sealing groove evenly, and then put the gasket into the sealing groove. The gasket shall be bonded evenly, pressed and dried naturally, or heated to 100 ℃ - 120 ℃ for two hours before drying. Check whether it fits evenly one by one, and remove the redundant adhesive. 5、 The characteristics of the assembly process of plate heat exchanger are: if the fluid enters from the left corner hole of the plate, it always comes out from the left corner hole of the plate, and vice versa. When assembling, it is necessary to correctly distinguish a plate and B plate, that is, take one side of the adhesive pad of the plate as the front face, and distinguish according to the direction of the guide groove. If the plate with the guide groove in one direction is a plate, then the plate with the guide groove in the other direction is B plate, but no mark is made on the plate. 6、 In hydrostatic test, four blind plates are made according to the size of connecting pipe flange, which are welded at the inlet and outlet, and pipes are welded on the plate to connect the compressor with the heat exchanger. Install a pressure gauge which has passed the verification and is within the validity period at the inlet and outlet, and the range of the pressure gauge should be twice the test pressure. The test pressure is 1.5 times of the working pressure. 1. In strict accordance with the above requirements for maintenance, the quality fully meets the design requirements, load test 72 hours without leakage. The temperature measurement results of heat exchange liquid: the inlet temperature of alumina mother liquor is 45.2oc, and the outlet temperature is 84.6oc; The inlet temperature of alumina semen is 97.0oc and the outlet temperature is 78oc, which meets the requirements of normal operation. 2. Cost savings. Because the material of the plate is ultra-thin crl7nil3mo2ti stainless steel, and the gasket is also special, it is very expensive to replace all the plates with new ones. After cleaning and checking, the single plate heat exchanger can save 250000-450000 yuan.