Preparation and operation procedures before board change operation

Plate heat exchanger is a kind of heat exchanger which is made of thin metal plates pressed into a certain corrugated shape, then stacked and fastened by clamping plates and bolts. Thin rectangular channels are formed among various plates, and heat exchange is carried out through the plates. The working fluid flows through a narrow and tortuous channel formed between two plates. The hot and cold fluids pass through the flow passage in turn, and there is an interlayer plate in the middle to separate the fluids, and heat exchange is carried out through this plate.

The structure and heat exchange principle of plate heat exchanger determine that it has the characteristics of compact structure, small floor area, high heat transfer efficiency, large operation flexibility, wide application range, small heat loss, convenient installation and cleaning, etc. The average temperature difference between the two media can be as small as 1℃, and the heat recovery efficiency can reach over 99%. Under the same pressure loss, the heat transfer of plate heat exchanger is 3 ~ 5 times of that of shell-and-tube heat exchanger, its floor area is 1/3, and its metal consumption is only 2/3.

In short, plate heat exchanger is an advanced heat exchange equipment with high efficiency, energy saving, material saving and investment saving.

1. Before using the equipment, check whether the clamping bolts are loose or not, and ensure that all bolts are uniform according to the specifications.

2. Before use, carry out water pressure test according to 1.3 times of the actual operating pressure, and keep the pressure for 30 minutes without leakage before putting into production.

3. There should be a bleed valve in the pipeline system. After opening, the air in the equipment should be discharged to prevent the air from staying in the equipment and reduce the heat transfer effect.

4. Installation of inlet and outlet connection pipes of cold and hot media should be strictly in accordance with the direction specified in the factory nameplate, otherwise it will affect the performance of the equipment.

1. When starting the operation, it is necessary to open the valve at the outlet of the cold and hot medium, then slowly open the valve at the inlet of the cold side, and then open the inlet valve at the hot side. If the pressures of the two media are different, the low-pressure side valve should be slowly opened first, and then the high-pressure side valve should be slowly opened.

2. When stopping operation, cut off the high-pressure side fluid slowly first, and then cut off the low-pressure side fluid. Please note that this will greatly contribute to the service life of the equipment.

3. The equipment should be operated within the working temperature and pressure range specified by this product. Over-temperature and over-pressure may damage the sealing performance and cause leakage. No violent impact during operation.

I. Installation and Commissioning

1. A certain maintenance site should be reserved around the position where the plate heat exchanger is installed.

2. Before installation, clean the pipeline connected with it, so as to avoid sand, oil, welding slag, etc., and other sundries entering the plate heat exchanger, which will cause the flow to block or damage the plate.

3. Before putting into use, check whether all clamping bolts are loose, and tighten them if any.

4. The starting and stopping sequence of the plate heat exchanger is as follows: when starting up, first open the medium valve on the low pressure side, and then slowly open the medium valve on the high pressure side after the medium fills the channel of the plate heat exchanger; When shutdown, first close the medium valve on the high pressure side, and then close the medium valve on the low pressure side.

5. If there may be large granular sediment or sundries in the medium, the plate heat exchanger should be equipped with the decontamination device produced by our company.

Second, the maintenance and maintenance

As the plate heat exchanger works for a long time, the surface of the heat transfer plate will produce different degrees of dirt and sediment, which will increase the flow resistance and reduce the heat transfer performance, mainly showing that the pressure difference of the outlet pressure gauge increases and the outlet temperature of the cold medium decreases, so it must be checked and cleaned.

The specific steps are as follows:

1. Close all inlet and outlet valves of the plate heat exchanger and drain the fluid in the heat exchanger.

2. The ordinary plate heat exchanger can be disassembled from the system, and then the clamping bolts can be uniformly loosened and disassembled for cleaning.

3. The hanging plate heat exchanger can be disassembled from the system, directly and evenly loosen the clamping bolts and remove them, move the movable pressing plate to one end of the bracket, tilt the upper end of the heat transfer plate toward the movable pressing plate, and then remove it from the hanging opening of the upper guide rod, and make the lower end of the heat transfer plate separate from the lower guide rod, and then take out the plate.

4. When washing the heat transfer plate, you can only use a copper wire brush or a limit brush to wash it. Do not use a wire brush to wash it, so as to avoid damaging the heat transfer plate and reduce the corrosion resistance. You should also be careful not to hurt the sealing gasket when washing it.

5. After the heat transfer plate is washed, it should be cleaned with clean water, and the sealing gasket should be wiped clean with clean cloth or cotton yarn.

6. The aging sealing gasket should be replaced, and the gasket should be bonded with adhesive. The method is to remove the aging sealing gasket, then clean the sundries in the plate groove, fix the new gasket with adhesive, and keep it straight and cured for 24 hours before reassembling and clamping to the clamping size.

7. If the plate heat exchanger is not used for a long time, the bolt should be loosened to 1.1-1.2 times the clamping size, and then clamped as required when in use.

8. When the plate heat exchanger is running frequently, it should be analyzed if the medium flows out in the signal hole. If the bolt is loose or elongated due to long-term heat exchange, it should be clamped again as required, but it should not be too tight to avoid crushing the heat transfer plate.

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