How to address the scaling issue in the supernatant during PVC production by the calcium carbide method
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Those familiar with the production of PVC using the calcium carbide method know that a large amount of wastewater (supernatant) is generated during the production process. Discharging this water is not conducive to environmental protection and the harmonious development of nature, and it also increases the production costs for enterprises. Reusing the supernatant can effectively solve this problem. However, based on production experience, the supernatant can easily cause scaling and blockages in pipes and equipment during reuse, which hinders the safe and stable operation of the production process over long periods of time. Please use your own production experience to discuss how to solve this problem, ensuring that the solution is convenient and reliable without compromising the safety and stability of production. Thank you!
I’m not sure where the original poster is referring to; the liquid cleaning equipment and pipes here have been in use for over 5 years without any signs of blockage.
In my opinion, two tanks should be installed: in one tank, a flocculant is added to cause the suspended particles to clump together for subsequent treatment, while in the other tank, a dispersant is added to prevent blockages in the piping system.
Make sure the flow rate is high, and avoid large temperature changes during transportation; blockages generally do not occur within a few years
This post was last edited by wang*neng on 2010-5-24 at 13:31. If scaling occurs frequently in your area, check whether there are any areas where the two water circuits mix together. Generally, process water and slurry water are used, along with an industrial water supply. The water inlet valve of the generator is prone to internal leakage, and scaling can easily occur if the two water streams mix together. Because industrial water contains carbonate ions. It turns out we are really good at scaling and clogging pipes. Later, the two streams were supplied through separate pumps, with separate pipelines for the gold slurry devices; the pipelines hardly ever got clogged. During parking for maintenance, the distribution panel is mainly cleaned.
What kind of equipment do you use for mud washing? Is it a regular filter or something else? Please advise, thank you!
Deionized water is used for the supernatant, and it generally does not tend to form scale. Look for other reasons.
Reply to 7# wang*neng: The supernatant is the filtrate obtained through filtration in a filter press; it is the upper layer of liquid that remains after sedimentation and is reused in the generator or sludge washer. It is characterized by high temperature and high calcium content, which makes it prone to causing scaling in pipes and equipment when reused.
Reply to 8# antwxh: I see now; I mistook it for the centrifugation mother liquor! The supernatant of calcium carbide slurry does tend to scale easily; in addition to following the suggestions put forward by Shanghai You, it is also recommended to use plastic pipes, which can help reduce scaling as well.
I guess it refers to acetylene generation? We don’t handle it here; when it’s reused, the nozzles in the slurry catcher tend to get clogged, so we just replace them frequently. . . The pipeline from the slurry catcher to the generator is relatively thick and has never been clogged. . .
Reply to 1# longyug: It is recommended that when using the supernatant, you first introduce it into a clarifier and use a fan to aerate the supernatant, allowing calcium hydroxide in it to react fully with carbon dioxide before sending it back to the generator for reuse; this will prevent scaling.