Method for cleaning and protecting plates of plate heat exchanger

Method for cleaning and protecting plates of plate heat exchanger

In addition to maintenance under special circumstances, the plate heat exchanger should also be regularly maintained. Due to the convenient disassembly and assembly of the plate heat exchanger and simple maintenance, special tools and equipment are generally not needed. Different methods can be used according to different situations. If the equipment does not leak, but the heat transfer system K has dropped, you can use a closed circuit system to pump the descaling liquid into the equipment and circulate for several hours without disassembling the heat exchanger. OK. There is no such condition on site, and when the equipment is disassembled or the scale is found to be not too serious, you can wash it directly with water without removing the plate, while scrubbing with a soft brush.　

　　 1. Normal operation and maintenance　　

　　 1. For equipment that needs maintenance, the heat exchanger should be disassembled in the reverse order of installation.

　　2. Equipment used in the petroleum and chemical industries should be regularly maintained according to the maintenance cycle.

　　 3. If the medium in the equipment is flammable, explosive or corrosive, it should be repaired at least once a year.

　　4. If the plate heat exchanger used in other industries does not leak, it can be repaired once every three years.　　

　　 2. Cleaning and protection of plates　　

　　 Keeping the plate clean is one of the important conditions for maintaining a high heat transfer coefficient. Between the plates, the medium moves along the narrow and tortuous flow channel. Even if a not too thick scale is produced, it will cause changes in the flow channel, which will significantly affect the movement of the fluid, increase the pressure drop, and increase the heat transfer coefficient. For example, a sugar factory uses a plate heat exchanger for heating. Because the secondary water is not well treated, the flow channel is blocked in only two months during use and cannot continue to operate.

　　1, chemical cleaning method

　　This method is to circulate a chemical solution through the heat exchanger to dissolve and discharge the dirt on the surface of the plate. This method does not need to disassemble the heat exchanger, simplifies the cleaning process, and also reduces the cleaning labor. Because the plate corrugation can promote the violent turbulence of the cleaning liquid, which is beneficial to the dissolution of the scale layer, the chemical cleaning method is an ideal method.

　　 2. Mechanical (physical) cleaning method

　　This method is to manually wash the plate with a brush, so as to achieve the purpose of removing the dirt on the surface of the plate. Although this method is relatively straightforward, it is not easy to clean the harder and thicker scale layer.

　　3. Comprehensive cleaning method

　　For the case where the dirt layer is relatively hard and thick, it is difficult to clean it by simply using one of the above methods. The comprehensive method is to first soften the scale layer by chemical cleaning method, and then remove the scale layer by mechanical (physical) cleaning method to keep the plate clean.

　　 4. Matters needing attention when cleaning

　　① The solution must maintain a certain flow rate during chemical cleaning, generally 0.8～1.2m/s. Its purpose is to increase the turbulence of the solution.

　　② Different chemical cleaning solutions should be used for different dirt. In addition to the frequently used diluted soda ash solution, 5% nitric acid solution can be used for scale. For the scale generated in the production of soda ash, 5% hydrochloric acid s

olution can be used. But do not use chemical lotions that corrode the plates.

　　③ During mechanical (physical) cleaning, it is not allowed to use carbon steel brushes to scrub the stainless steel plates, so as not to accelerate the corrosion of the plates. At the same time, the surface of the plate cannot be scratched or deformed.

　　④ The cleaned plate should be rinsed with clean water and wiped dry, and the plate should be prevented from being deformed when placed.　

　 　　Three, the characteristics of the gasket and its replacement　

　 　　 Due to the continuous expansion of the application field of plate heat exchangers, different media and processes have different requirements for temperature resistance, pressure resistance and corrosion resistance. It is obviously impossible to use a "universal" gasket to adapt to all situations, and gaskets of different materials should be used for different situations. The commonly used gasket cross-sectional shape is a six-sided row. Commonly used gasket types include natural rubber, neoprene, EPDM, silicone rubber, fluororubber, asbestos fiberboard, etc.

　　 Plate heat exchanger gaskets should be replaced in time if they leak, break, or age during use. Replacement should be done in the following order.

　　① Remove the used gasket. Note that when disassembling, there must be no scratches in the gasket groove.

　　② Use acetone, methyl ethyl ketone or other ketone solvents to remove the residual glue in the gasket groove.

　　③ Clean the gasket groove and gasket with a clean cloth or cotton yarn.

　　④ Apply the adhesive evenly to the gasket groove.

　　⑤ Put a clean new gasket on the board.

　　⑥ The plate with the gasket should be placed in a flat, cool, and ventilated place before it can be installed and used.