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Correctly replace the tubes of the graphite heat exchanger
- 2019-11-10-

The graphite heat exchanger equipment has been used for a long time, and the graphite tube may be damaged. At this time, it is necessary to timely check whether there is a leak, and if there is a leak, it needs to be replaced in time. The inspection method is mainly to test the pressure of the tube one by one to see which tube has leaked. However, it is too slow to check one by one. For example, it takes five to check one tube of the graphite heat exchanger. Minutes, then it takes nearly two days to check a device.

For the shell-and-tube type graphite heat exchanger, water can be transported to the tube side and wait for the water surface to exceed 50 mm to 100 mm above the upper tube sheet. At this time, the valve on the discharge tube can be opened to remove the graphite. The water leaking from the heat exchanger to the shell side is drained. At this time, special attention needs to be paid. It is easy to find the problematic graphite tube in the equipment. When a vortex appears in the water surface of the upper tube sheet, Quickly use a plug to plug the nozzle of this tube, and at the same time close the valve of the graphite heat exchanger discharge pipe. Repeatedly after that, find the damaged graphite tube.
Everyone needs to pay attention to the use of graphite heat exchanger equipment. When the graphite tube is damaged at the beginning, it is only a small crack. Many users and friends think it is irrelevant. In fact, these cracks also need to be treated early after detection. Do not wait The graphite heat exchanger cannot be processed before it is in operation, and it will consume a lot of manpower and material resources, and the production cost will increase a lot.

The performance of graphite heat exchanger equipment is as follows:

1, the surface is not easy to scale: graphite and most media have very little affinity, so dirt is not easy to adhere to the surface, especially used in condensation equipment and crystallization equipment.

2. Excellent corrosion resistance: Various types of carbon and graphite have excellent corrosion resistance to all concentrations of hydrochloric acid, phosphoric acid and hydrofluoric acid, including fluorine-containing media. The highest application temperature is 350 ℃ -400 ℃, that is, carbon The temperature at which graphite begins to oxidize.

3. Excellent thermal conductivity: Graphite has good thermal conductivity. It is a material with higher thermal conductivity than non-metallic materials. The thermal conductivity is 2 times that of carbon steel and 7 times that of stainless steel. Therefore, it is suitable for heat transfer equipment.

4. Resistance to certain high temperatures: The temperature of impervious graphite depends on the type of impregnating material. For example, phenol-impregnated graphite can withstand 170-200 ° C. If an appropriate amount of silicone resin is added to impregnate graphite, it can withstand 350 ° C. When phosphoric acid When deposited on carbon and graphite, the oxidation resistance of carbon and graphite can be improved, and the actual operating temperature can be further increased.

When the graphite heat exchanger is used, if it is used improperly, the tube will break or the bonding seam will leak. The reasons are as follows:

1. When the system warms up, because the heating rate is too large, it will cause the shell side pressure of the graphite heat exchanger to rise sharply, and the graphite tube will be damaged by impact.

2. Graphite heat exchanger tubes are unevenly heated.

3. Excessive force during cleaning will cause damage to the column.

4. Due to the increase of the graphite heat exchanger use time, some scaling will occur on the tubes. The scaling coefficient of the graphite heat exchanger is different from that of the non-scaled graphite heat exchanger. The thermal stress is overloaded, causing graphite The heat exchange tube is broken.