Procedures for overhauling plate heat exchanger
1. Plate cleaning:
(1) A clean and oxide-free surface of the plate is a necessary condition to ensure tightness. When the thermal efficiency of the plate heat exchange
r is significantly reduced and the pressure drop is significantly changed, the fouling is serious, and the plates should be disassembled and cleaned.
(2) When cleaning the sealing groove, lift the washer with a screwdriver, gently remove it (or lightly bake it on the back side, but avoid discoloration of the metal), and then tear it off. Use acetone methyl liquid or other ketone organic solvents to clean the sealed tank.
(3) The cleaned board should be rinsed with clean water first, and then dried with a clean cloth. No foreign particles or fibers are allowed on the board.
2. After checking and confirming that the workload is cleaned, carefully check the plates. There are three inspection methods:
(1) Coloring method: check with coloring agent;
(2) Light transmission method: a light source is placed on one side of the plate, and people check on the other side;
(3) One-sided pressure test method: One-sided water test pressure to 0.35MPa (gauge pressure), if there is water at a very low place on the other side, quickly check the wetness of the plate. The light transmission method is used for inspection, which has the advantages of convenience and low cost, and is suitable for inspection of new and old plates.
3. Gasket pasting: Use adhesive or strong adhesive to evenly coat a layer on the bottom of the sealing groove, and then put the gasket in the sealing groove, stick it evenly, pressurize, dry naturally, or heat to 100℃ Dry at -120°C for two hours. Check one by one to see if the fit is even, and remove excess bonding
4. The characteristic of the plate-plate heat exchange
r process combination is: if the fluid enters from the hole on the left corner of the plate, it will always come out from the hole on the left corner of the plate, and vice versa. When assembling, it is necessary to distinguish A board and B board correctly, with the side of the sheet adhesive pad as the front, distinguish according to the direction of the diversion groove, and set the diversion groove in a certain direction as the A plate, then the diversion groove The board in the other direction is the B board, but there is no mark on the board.
5. Water pressure test: Make four blind plates according to the size of the pipe flange, weld them to the inlet and outlet, and weld the pipes on the plates to connect the compressor to the heat exchanger. Install a pressure gauge that has passed the verification and is within the validity period at the inlet and outlet. The range of the pressure gauge should be twice the test pressure.