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Brief introduction of cleaning method of plate heat exchanger

source:http://gzjchuang.com/news149684.html  release time:2019-10-22 14:40:00

In recent years, the use of plate heat exchanger is more and more extensive, more and more attention and use by heating enterprises, and with its advantages of light weight, small floor area, less investment, high efficiency of heat exchange, flexible assembly, easy to remove scaling and so on to replace the shell and tube heat exchanger, now briefly introduces the cleaning method of plate heat exchanger.

When the plate heat exchanger is used for a long time, some impurities will form in the channel between plates and block the fluid, resulting in the increase of the pressure difference between the inlet and outlet, and the reduction of the heat exchange effect. When this happens, the plate heat exchanger needs to be cleaned.

Cleaning is divided into 5 steps

1. Washing, 2. Pickling, 3. Alkali washing, 4. Water washing, 5. Record

Rinse

Before pickling, the heat exchanger shall be rinsed in an open way to ensure that there is no mud, scale and other impurities inside the heat exchanger, which can not only improve the pickling effect, but also reduce the acid consumption of pickling, and pour the cleaning solution into the cleaning equipment, and then inject it into the heat exchanger.

pickling

The heat exchanger filled with acid solution was immersed in static state for two hours, and then it was circulated continuously for three to four hours. The positive and negative cleaning should be carried out alternately every 0.5 hours. After pickling, if the pH value of the acid solution is greater than 2, the acid solution can be reused. Otherwise, the acid solution shall be diluted and neutralized and discharged.

Caustic washing

After acid cleaning, NaOH, Na, Po and softened water are prepared in a certain proportion, and the heat exchanger is alkaline washed in the way of dynamic circulation to achieve acid-base neutralization, so that the plates of the heat exchanger are no longer corroded.

washing

After alkali washing, wash the heat exchanger with clean softened water for 0.5h repeatedly, and thoroughly wash the residue in the heat exchanger.

Record

During the cleaning process, the time of each step shall be strictly recorded to check the cleaning effect. In short, after cleaning, the heat exchanger should be pressure tested. It can only be used after it is qualified.

Requirements for scale cleaning

1) acid pickling temperature: after several acid pickling tests, it is found that the increase of temperature can improve the effect of acid pickling and descaling, but if the temperature is too high, it will aggravate the corrosion of acid pickling solution on the heat exchanger plate, and the corresponding acid pickling temperature should be controlled at 60cc.

2) concentration of pickling solution: the pickling solution should be prepared according to the concentration of 81.0% formic acid, 17.0% water, 1.2% buffer and 0.8% surfactant, with excellent cleaning effect.

3) pickling method and time: pickling method shall be combined with static immersion and dynamic circulation. The pickling time is 2 hours static soaking and 3-4 hours dynamic cycling. In the acid pickling process, the acid pickling concentration should be tested frequently. When the difference between the two adjacent test concentrations is less than 0.2%, the acid pickling reaction is considered to be over.

Guangzhou JieChuang Industrial Equipment Co., Ltd.

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