Discussion on how to use low-mercury catalysts to extend duration

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The last edit to this post was made by sdw831024 on 2016-4-15 at 15:34. To stimulate discussion, I will outline the measures we take to keep the consumption of low-mercury catalysts at 0.8% per ton of product; please share your thoughts: (The plant operates at over 85% of its designed capacity throughout the year.) 1. The purity of hydrogen chloride and acetylene should be above 99%, with moisture levels below 500 ppm. 2. The exit temperature of the preheater should be above 95°, and the inlet temperature for further conversion should be above 90°. 3. Low-mercury catalysts are used throughout, without any replacement ； (But pay attention to the method of use.) 4. When replacing a single catalyst, in addition to considering the conversion rate and usage time, it is possible to determine the order of replacement based on the inlet and outlet temperatures. 5. The connection point where the exhaust gas is reintroduced into the conversion system is located before the preheater; pay attention to changes in composition and flow rates, and be sure to take into account any excess hydrogen chloride present in this section. 6. After the load on the conversion system decreases, it is necessary to reduce the feed rate to the converter in order to maintain its activity – this is crucial. 6. When using new low-mercury catalysts for pre-conversion, it is necessary to exercise proper control (especially over activity control in the initial stage, activity enhancement in the intermediate stage, and activity activation in the later stage) in order to extend the service life of the post-conversion process ； A positive cycle is formed. 7. Reduce the frequency of leaks in the converters as well as the frequency of starting and stopping them, because even if a leak is detected promptly, it may already have had an impact on other converters ； The start-up and shutdown processes are mainly due to poor control; this affects the catalyst’s activity in the short term. If adjustments are not made in a timely manner, the catalyst’s poor activity persists. This factor directly affects the active life of the catalyst. Let’s write these down first; insights from 10 years of experience ； I hope to provide some assistance to sister organizations that use the calcium carbide process with low-mercury catalysts for PVC production ； If possible, the moderator could set this as a permanent pinned post so that I can communicate well with everyone! Just because one company does well does not mean the entire industry is doing well; industry progress requires the joint efforts of everyone.