Views:3 Author:Site Editor Publish Time: 2020-07-14 Origin:Site
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 plate heat exchanger, the heat exchange The sediment and suspended matter in the device are gathered at the corner hole and the diversion area, which leads to a significant reduction in the area of the flow channel at this place, causing pressure loss mainly at this location.
②The 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 the plate heat exchanger has been running for a period of time, the pressure drop is too large due to the scaling of the plate surface.
2. Processing method
①Remove the dirt or scale in the heat exchanger flow channel, and clean the newly operated system once a week according to the actual situation. When cleaning the scale on the plate surface (mainly refers to CaCO3), choose a solution containing 0.3 sulfamic acid or The 0.8 nitric acid solution containing 0.3 urotopin, 0.2 aniline, and 0.1 potassium thiocyanate is used as the cleaning liquid, and the cleaning temperature is 4O~60C. When the equipment is not disassembled for chemical immersion cleaning, the inlet and outlet of the cold medium of the heat exchanger should be opened, or When installing the equipment, install the DN25 cleaning port on the inlet and outlet of the medium, and inject the prepared cleaning solution into the equipment. After soaking, rinse the residual acid with clean water to make the pH ≥7. Immerse in the liquid for 30 minutes, then gently brush the scale with a soft brush, and finally clean it with clean water. During the cleaning process, avoid damaging the plates and rubber pads. If you do not disassemble the mechanical backwash method, you should first place it on the medium inlet and outlet pipes Connect a pipe port, connect the equipment to the mechanical cleaning vehicle, and inject the cleaning liquid into the equipment in the opposite direction of the medium flow, the cycle cleaning time is 10~15 min, and the medium flow rate is controlled at 0.05~0.15m/s. Finally, use clean water to cycle Every time, make the mass concentration of Cl in the clear water controlled below 25mg/I.
②The secondary circulating water is best to use softened water after softening treatment. Generally, the mass concentration of suspended matter in the 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 more than 95℃, the concentration of Ca and Mg It should not be greater than 2mmol/L; when the water temperature is greater than 95°C, the Ca and Mg concentrations should not be greater than 0.3mmol/L, and the dissolved oxygen mass concentration should not be greater than 0.1mg/L.
③ For the central heating system, you can use the method of replenishing water once.
Knowing the reasons for the excessive pressure drop of the plate heat exchanger and the solutions, you can reduce the trouble when using the plate heat exchanger, everyone must remember it!