A plate heat exchanger is a high-efficiency heat exchanger assembled from a series of metal sheets with a certain corrugated shape. Thin rectangular channels are formed between various plates to exchange heat through the plates. So what are the reasons and treatment methods for the excessive pressure drop of the plate heat exchanger?
(1) Reasons for excessive pressure drop of plate heat exchanger
① The pipelines of the operating system are not purged normally, especially many dirt (such as welding slag) in the pipelines of the newly installed system enters the interior of the plate heat exchanger. Due to the narrow cross-sectional area of the flow path of the plate heat exchanger, the sediments and suspended solids in the heat exchanger gather at the corner holes and the diversion area, which leads to a significant reduction in the area of the flow path. The pressure is mainly lost in this area.
② The area of the plate heat exchanger was small when it was first selected, which caused the flow rate between the plates to be too high and the pressure drop to be large.
③ After running the plate heat exchanger for a period of time, the pressure drop is too large due to the fouling of the plate surface. Example: Our factory provides users with BR10 plate heat exchangers for the central heating system of water-to-water heat exchange. The design temperature of the primary water supply is 130 degrees.When designing and selecting the heat exchanger, the heat transfer coefficient is on the high side close to 5500w / (m2 · K), but it should be actually 3500w / (m2K). The design unit has a large flow margin when the pump is selected, resulting in a flow rate between the medium plates of the secondary side of the heat exchanger exceeding 1m / s, and an actual operating pressure drop of 0.2-0.3MPa, which makes the hydraulic balance of the secondary network severely out of balance.
(2) Treatment method for excessive pressure drop of plate heat exchanger
① Remove dirt or scale from the heat exchanger flow channel, and clean the newly operated system once a week according to the actual situation. ② The secondary circulating water is best to use softened water after softening treatment. Generally, the concentration of suspended substances in water is not more than 5mg / L, the diameter of impurities is not more than 3mm, and the pH is ≥7. When the water temperature is not greater than 95 ℃, the concentration of Ca and Mg should not be greater than 2mmol / 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 concentration of dissolved oxygen should be no more than 0.1mg / L.
③ For the central heating system, the method of replenishing water from the primary to the secondary can be used