Maintenance and maintenance of water-cooled chiller for injection molding machine1. Structure of water-cooled chiller
Water-cooled chillers are devices that exchange shell-side fluid (high-temperature oil) and tube-side fluid (low-temperature fresh water) through heat transfer tubes to exchange heat exchangers to lower the temperature of high-temperature fluid and achieve cooling.
Water-cooled chiller is mainly composed of water inlet cover, tube sheet, tube tube, heat transfer tube, baffle plate, sealing gasket and tripod. The space surrounded by the outer surface of the heat transfer tube and the tube barrel is called. The shell-side fluid and the tube-side fluid are exchanged and converted by the heat transfer tube, so that the temperature of the high-temperature fluid is lowered to achieve the purpose of cooling.
When using the chiller, it must not exceed the operating pressure and operating temperature indicated on the product nameplate and product certification. Except in special circumstances, only fresh water can be used as a cooling medium. The quality of fresh water is related to the cooling efficiency, the performance and life of the chiller.
Do not stop the machine for a long time. In order to prevent freezing, the fluid in the chiller should be released in time.
If the cooling effect is reduced, there may be dirt inside the pipe. The separated water inlet cover and return water cover should be removed for inspection. The chiller should be cleaned at least once every six months. An alkaline cleaning solution is used to clean the inside of the main body and the outside of the heating nozzle tube. For difficult interlayers, use weak hydrochloric acid solution to clean the body
2. Disassembly and assembly of open water cooler
Frozen with. -Rinse with clean water. Then rinse it with clean water and a soft brush. The decomposition steps of the water machine are:
(1) Completely close the inlet and outlet of the two fluids to prevent their flow
(2) Discharge the two fluids in the chiller and its connected pipes cleanly
(3) Remove the external part of the water chiller to make it in a decomposable state.
(4) Please mark before disassembling, especially fix the orientation of the tube sheet, to facilitate smooth assembly.
(5) Remove the return water cover and take out the o-ring.
(6) Remove the water inlet cover and take out the sealing gasket.
(7) Gently pull the tube bundle out of the tube, it is best to use vertical assembly and disassembly to avoid scratching the sealing surface of the moving tube sheet. The assembly order of the chiller is opposite to the disassembly order. At this time, insert a few round rods of appropriate diameter into the swimming side tube, the insertion depth does not exceed 300mm, and the tube can be gently filled into the tube when the tube is bundled. O-rings and seals should be replaced in due course, and the connecting bolts of the water cover and flange should be symmetrical and tightened evenly.
3. Sealing performance test of water freezing machine
Close the shell side outlet of the chiller with a screw plug, and pressurized water flows into the shell side inlet, as shown in Figure 2-121. Keep the pressure for 30 minutes, there should be no leakage at the inlet and outlet of the chiller and the flange connection, and the pressure should meet the pressure indicated on the product nameplate or product certification. When paying special attention to safety, the compression speed should be slow; no one should be in the direction opposite the screw plug and the water cover; before removing the screw plug and other parts of the water chiller, the pressure in the water chiller should be released first
. 4. Common faults and solutions
Common faults and solutions of chillers are shown in the table.
| Fault condition |
Site of occurrence |
Cause analysis |
Solutions |
| Fastening screws are not tightened |
Tighten fastening screws |
| Damaged sealing washer or O-ring |
Replace the sealing washer or O-ring with a new one |
| Damage of sealing surface in contact with sealing washer or O-ring |
Repair sealing surface or replace parts |
| Fastening screws are not tightened |
Tighten fastening screws |
| Middle flange tilt |
The middle flange is aligned with the connected flange |
| Screw plug not tightened |
Tighten screw plug |
| The plug is not wrapped with sealing tape |
Screw plug shall be rewound with sealing tape |
| O-ring damaged |
Replace the sealing washer or O-ring with a new one |
| Damaged sealing surface in contact with 0-ring |
Repair sealing surface or replace parts |
| |
The fluid flow cannot reach the design flow |
Increase fluid flow to design value |
| Too much dirt on both sides of the heat pipe |
Clean the heat transfer tube |
|
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