Plate heat exchanger is a kind of heat exchanger formed by pressing thin metal plates into heat exchange plates with a certain corrugated shape, then stacking them and tightening them with splints and bolts. Thin rectangular channels are formed between various plates for heat exchange. The working fluid flows through the narrow and tortuous channel formed between the two plates. Plate heat exchangers will experience excessive pressure drop during use. What causes the excessive pressure drop?
The reason for the excessive pressure drop of the plate heat exchanger: ①The pipeline of the operating system is not normally purged, and a lot of dirt in the newly installed system pipeline enters the inside of the plate heat exchanger. Due to the narrow cross-sectional area of the flow channel of the plate heat exchanger, the sediment and suspended solids in the heat exchanger gather at the corner holes and the diversion area, resulting in a large reduction in the flow channel area and the main pressure loss in this part. ② When the plate heat exchanger is selected, the area is too small, which causes the flow velocity between the plates to be too high and the pressure drop is too large. ③ After the plate heat exchanger has operated for a period of time, the pressure drop is too large due to scaling on the plate surface.
Treatment method for excessive pressure drop of plate heat exchanger: ① Remove dirt or plate fouling in the flow channel of the heat exchanger. For the newly operating system, clean it once a week according to the actual situation. When cleaning the scale (CaCO3) on the surface of the board, use 0.3 sulfamic acid solution or 0.8 nitric acid solution containing 0.3 urotropine, 0.2 aniline, and 0.1 potassium thiocyanate as the cleaning solution, and the cleaning temperature is 40 ~ 60 ℃. ② It is better to use soft water after softening treatment for secondary circulating water. Generally, it is required that the concentration of suspended solids in water is not more than 5 mg/L, the diameter of impurities is not more than 3 mm, and the pH is ≥ 7. When the water temperature is not more than 95℃, the concentration of Ca and Mg should not be more than 2 mmol/L. When the water temperature is greater than 95℃, the concentration of Ca and Mg should be no more than 0.3mmol/L, and the mass concentration of dissolved oxygen should be no more than 0.1 mg/L. ③For the central heating system, the method of supplementing water once and twice can be used.