【JST-059】Chlor-alkali One-on-One Q&A Office
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This post was last edited by Firefly on 2015-4-10 08:38. Username: tclvjian. Major: Applied Chemical Engineering. Fields of expertise: brine, electrolysis, hydrogen chloride, liquid chlorine. Specialized skills: electrolysis. Work experience: After graduating from school in 1992, I started working on the front lines in a chlor-alkali plant, and through hard work I have risen to a management position today. Online hours: 8:00-17:00. I hope to learn together and exchange ideas with fellow sailors through this post, so as to improve together. Let our seas and rivers become more and more wonderful!
When producing caustic soda using the ion exchange membrane method, the reaction Na2CO3 + Ca(OH)2 → 2NaOH + CaCO3 is utilized. So how can efficiency be improved? Aside from increasing the amount of reactants and removing the products promptly, it’s a non-professional question from a non-expert… Hahaha, just taking a photo~~
Wow, is this allowed too? I’m ignorant. Your knowledge of chemical equilibrium is quite good.
First, let’s support the old moderator; I have a question regarding electrolysis. For brine that comes from saltwater, if excessive chlorine is detected before it passes through the chelating resin tower, how should it be handled?
An ion membrane that is not afraid of calcium and magnesium has been created by Smart Little Wood! Hehe
That’s not right, hahaha. It’s okay; I was just meddling without reason. If it doesn’t work, please delete it – my skills are really poor at this~~ Hehe
I know Little Wood is deliberately testing me, huh. Na2CO3 + CaCl2 → 2NaCl + CaCO3. In production, it is necessary to improve efficiency while also considering safety; generally, the amount of excess alkali is kept between 0.3–0.5 grams per liter, and a reaction time of 15–20 minutes must be allowed after adding sodium carbonate. (I haven’t touched chemical reaction equations in a long time.)
The damage caused by free chlorine to the chelating resin in the resin column is irreversible; therefore, free chlorine must be removed before it enters the resin column. If the free chlorine level is too high, the resin tower should be stopped first to prevent filtered brine from entering it, and then the brine in the filtered brine tank should be sent back to the primary brine tank for re-refining. Different companies may employ different methods due to their varying processes; in any case, it is necessary to remove free chlorine from the filtered brine before operating the resin tower and allowing fluid to flow through it.
Our process cannot directly return to the brine section; the emergency solution is to add sodium sulfite directly to the filtered brine tank. By controlling the addition amount, an impact on the membrane cannot be avoided.
Adding sodium sulfite to the filtered brine tank should be a last resort, as doing so increases the sulfate content in the refined brine, and a large amount of high-valent ions such as calcium and magnesium will take advantage of this situation, increasing the load on the resin tower. Additionally, it would be advisable to check the condition of the membrane used for once-through brine treatment as high levels of free chlorine can still cause damage to rubber-based equipment. Sodium sulfite is a double-edged sword; too much or too little saltwater can have an impact on the system.
I have a question: for the water mist collector used in the chlorine drying process, the kind with filter elements installed inside it, what is the operating pressure for such equipment? I work with fiberglass-reinforced plastic equipment. I noticed that many of the original Tianchen models had flat bottoms, but later some of them were made with round bottoms. I was just wondering, experts, how much is the pressure drop here? If you have any information on this topic, please feel free to send it to me. Thank you to all my friends from Sichuan; I work in the field of fiberglass equipment, and we can also discuss any needs related to fiberglass. jzgrp@hotmail.com