Liquid caustic pump mechanical seal issues
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32% liquid caustic – previously a fluorine pump was used, and white crystalline solids often formed at the mechanical seal area; later an IJ caustic pump with a 171 type mechanical seal was installed. However, the cooling water contained caustic substances, resulting in pH levels of 12 and 13. With strict environmental regulations in place now, are there any better pump types or corrective measures available?
For fluorine pumps, regularly flushing the mechanical seal area helps to reduce the amount of white crystalline solids.
1. The mechanical seal leakage is above the acceptable level; it needs to be replaced. 2. The cooling water for the mechanical seal should be supplied through a separate circulation tank
Magnetic fluorine-lined pump, no mechanical seal and no leakage. The downside is that it cannot run idly. It is generally recommended to reduce the concentration of the alkaline solution from 32% to 25%; crystallization does not usually occur in winter, and this is very important. Regarding the excess water, you can make the necessary reductions in other parts of the process.
It involves installing a liquid storage tank on top of the pump; as the cooling water keeps circulating, the alkaline concentration in that storage tank remains very high
All materials used for machine seals should be alkali-resistant, which is no problem; they should also be environmentally friendly
It turns out that the centrifugal pumps used in our liquid caustic irrigation areas produce a lot of white caustic at the pump head, which has severely damaged the pump foundations. Some of the pumps have now been replaced with magnetic pumps, while others still remain unchanged. It’s working fine; no repairs were done in the workshop either. I’m not sure about the specific material
Adjust the pressure of the seal flushing water to be slightly higher than the pump outlet pressure, so that it can serve as an isolation fluid.
For magnetic pump use, and since the temperature in the alkali tank is not high, choosing a magnetic pump is definitely the right choice
Over time, some water will also enter the alkali tank