Optimal control of the synthesis ratio for hydrogen chloride
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This post was last edited by sunjl1981 on 2013-1-6 at 23:55. Nowadays, companies are all striving to save energy and improve efficiency; some of them have implemented MES systems or advanced control technologies. In my opinion, given the current level of production automation in chlor-alkali enterprises, there are still some areas that can be optimized at the PCS layer (process control layer). For example, in the case of the synthesis ratio for hydrogen chloride, optimizing this ratio is very significant for ensuring production safety as well as reducing costs and increasing efficiency. I would like to discuss with everyone how to optimize the ratios for hydrogen chloride synthesis, and I’m also eager to hear how those companies that have already carried out such optimization did it. I hope the experts here will be kind enough to offer their guidance. I think there are three approaches for optimizing the ratio of hydrogen chloride: A is to measure the purity of chlorine and hydrogen, and then adjust the ratio according to the requirements of the manufacturing process. B measures the purity of hydrogen chloride as well as the chlorine content in it, and then adjusts the flow rates of chlorine and hydrogen using a ratio adjustment method. The purity of chlorine gas, hydrogen gas, and hydrogen chloride is all measured, and the flow rates of the two gases are adjusted using selective ratio control. Analysis: Although Option A can accurately adjust the actual ratio of the two gases to the process requirement range of 1.05–1.1, it does not seem to indicate whether 1.05 or 1.1 is the optimal value for this setup; manual analysis of the hydrogen chloride purity and chlorine content is still required to determine this. In my opinion, Option B has the lowest investment cost; it ensures safety by measuring free chlorine, while also allowing for optimization of the mixing ratios. However, adjusting the ratio of the two gases by analyzing hydrogen chloride purity and chlorine content is not very straightforward; an optimized algorithm is definitely required. Plan C seems to be the most perfect option, but the investment required is too high, so it doesn’t seem necessary after all. Everyone, please share your opinions as well. ， ， -
Ratio control is a key step in achieving automated control. To maintain the balance of the system, it is essential to accurately monitor the acid concentration and free chlorine levels. By monitoring these two parameters online and feeding the data back to the flow meter in the synthesis furnace, the control valve can be actuated to achieve proportional control. This control scheme is very effective at regulating excess chlorine, but the effect on excess hydrogen is not as significant. It is also difficult to control when the purity of chlorine and hydrogen changes sharply. I still can’t think of any better solution right now. Look at the correct answer downstairs.
To share my personal opinion, our synthesis furnace is currently under brake control, but the unit does not have a free chlorine detector. I believe it is necessary to add one; just in the past two weeks, we encountered some problems with our liquefaction unit, which resulted in an increase in the purity of chlorine gas. Additionally, the pressure in the chlorine gas buffer tank for hydrochloric acid increased by 8–10 KPa. Since the operators did not notice this, chlorine gas started to escape from the hydrochloric acid exhaust system. (The hydrochloric acid we use is made from the residual chlorine from the liquefaction process; after adding elemental chlorine in the appropriate proportions, its purity is generally around 85%. If there are problems with the liquefaction process on a given day, the purity of the chlorine increases, which leads to chlorine leakage.) ) As for online monitoring of hydrogen, a cautious attitude is adopted.
Online chlorine analyzers are good, but imported ones are too expensive; domestic ones are not yet up to standard
Sorry, it was a typo. What I meant is: Hydrogen chloride online analyzers are good, but imported ones are too expensive; domestic ones are not yet up to standard
Excuse me, friend upstairs: what are the brands of imported online hydrogen chloride analyzers?