Hydrochloric acid free chlorine
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This post was last edited by sunjl1981 on 2013-1-6 23:37. Our company uses a Japanese Asahi Kasei resin tower. The regeneration step uses high-purity acid produced by a two-in-one graphite furnace. In the past, my company used a resin tower from a chlorine project. The regenerated hydrochloric acid requires the addition of sodium sulfite to treat free chlorine. However, this process is not available now. I would like to ask you whether it is necessary to add this process to prevent resin poisoning. # , , &
If the two-in-one graphite furnace is well controlled, the free chlorine of the high-purity acid should be qualified, and there is no need to add sodium sulfite for treatment. However, if you do not operate well and the free chlorine exceeds the standard, you should add sodium sulfite to treat the free chlorine. After all, free chlorine is harmful to the resin.
In this case, our process designers should consider the worst case scenario and add sodium sulfite treatment, that is, cycle and reanalyze after addition.
Domestic two-in-one furnaces cannot guarantee full combustion of chlorine and hydrogen due to problems with the furnace head structure (although there is an excess of 5%-10% of hydrogen), so the free chlorine of hydrochloric acid after absorption is relatively high, generally exceeding 20ppm. If it is used for resin regeneration, I personally feel that it is necessary to add a step to remove free chlorine. However, if sodium sulfite is used, there are the following issues to pay attention to: 1. High-purity water should be used for preparation. A static mixer can be added to the hydrochloric acid delivery pipeline. A metering pump can be used to add sodium suboxide. It is best to add a filter (below 100 microns) before entering the resin tower to prevent suspended solids from clumping the resin and increasing the pressure difference. ； 2. The acid used for resin tower regeneration is placed in a separate pipeline and is separated from the acid adding pipeline of the electrolytic tank. ； 3. Personally, I feel that adding sodium sulfite to hydrochloric acid is not good at removing free chlorine, because only under alkaline conditions (PH10-11), free chlorine can be completely removed. Since the poster has experience in using this, welcome to introduce it!
Personally, I think that the domestic two-in-one graphite furnace is currently used for production. As long as the free chlorine of high-purity acid is well controlled, the free chlorine should be guaranteed. The key is for operators to pay attention to their sense of responsibility, strictly control the proportion of reacted chlorine and hydrogen, and avoid excessive chlorine.
Personally, I feel that it is still necessary. Our company's hydrochloric acid is high-purity hydrochloric acid, and sodium sulfite needs to be added frequently. After all, free chlorine will poison the resin, and there is not much sodium sulfite added.