How to control CO2 purity
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How is the purity of CO2 gas controlled in the decarburization and purification system? Our company requires a purity level of over 98.5%, and it can be difficult to maintain this standard sometimes.
It depends on the decarbonization process; different processes require different adjustment methods.
This post was last edited by 654262293 on 2010-10-16 13:17. Reply to 1# Ammonia purification: What process do you use for decarburization? Different processes require different adjustment methods; it’s best to explain the process you are using so that others can help analyze and solve the issues for you.
Our factory uses NHD decarburization technology. When reviewing previous posts, I noticed that some companies adjust purity by controlling the water content; generally, it’s not easy to control the water content in the decarburization process. If anyone knows, could you let me know what level is appropriate? Also, when our plant is operating at full capacity, it becomes more difficult to keep the CO2 purity within the specified range.
Please clarify whether you are using pressure swing adsorption for carbon removal or PC liquid for carbon removal – let’s discuss this together
Reply to 5# lzw299: You need to look carefully; it was already mentioned above that NHD decarburization is used.
This post was last edited by 654262293 on 2010-10-16 at 13:17. I have never worked with NHD decarburization, but it’s certainly not advisable to use the method of controlling the water content in the solution to regulate the purity of CO2 in the product gas, as you mentioned. Whether carbon propylene liquid decarburization or low-temperature methanol washing is used for decarburization (I have done both), there is no mention of using the water content in the solution to control the purity of CO2 in the product gas; in both cases, carbon propylene liquid decarburization and low-temperature methanol washing improve the purity of CO2 in the product gas by controlling the pressure in the intermediate flash tank. Could you briefly explain the NHD decarburization rich liquid process? Let me help you analyze it.
The last edit to this post was made by 654262293 on 2010-10-16 at 13:18. It’s the first time I’ve heard that water content is used to control carbon dioxide in NHD decarburization; after all, NHD decarburization is a fairly mature process. If carbon dioxide cannot be controlled properly, it might be due to the following reasons: 1. Excess water content in the system； 2. The temperature of the imported gas is too high ； 3. The solution temperature is too high ； 4. The high flash pressure is too high ； 5. Overload ； 6. The solution has a low concentration of solute. Caused by reasons such as these.
The last edit to this post was made by 654262293 on 2010-10-16 at 13:18. Let me briefly explain our decarburization rich liquid process: The rich liquid coming out of the decarburization tower goes into the decarburization high-flash tank, then into the ammonia cooler, and subsequently into the high-pressure low-temperature flash tank (the purity of CO2 produced by flashing is required to be 98.5%). After that, it enters the stripping tower; the pressure in the high-flash tank has been reduced to its minimum level ； The solution temperature and water content are normal ； The load is nearly at full capacity, without exceeding it ； The inlet air temperature is 5-6 degrees. The problem now is the increase in circulation volume; the CO2 level has decreased, but the urea data indicate a high dehydrogenation temperature. It’s not possible to have both.
A purity analyzer is used, with automatic control
Reply to Floor 9 on ammonia purification: If the urea feed gas is of qualified quality, then it’s not a decarburization issue. An increase in the urea dehydrogenation temperature only indicates a reduced dehydrogenation capacity; it has nothing to do with decarburization.