Linde cryogenic methanol absorption rate
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In Linde’s low-temperature methanol absorption process, what are the typical absorption rates for CO2 and H2S in the absorption tower? :) Thank you! 【In an absorption tower, what is the absorption rate of low-temperature methanol for CO2 and H2S?】 What are the typical operating temperature and pressure of a absorption tower? 】 This post was last edited by liufangrong on 2009-4-14 09:23 ]
The absorption rate can exceed 99.9%, with even better performance against H2S
The gas absorption rate can be calculated based on the analysis of the gas composition entering and leaving the absorption tower. Typically, the operating temperature for low-temperature methanol washing is between -30 and -70°C. The relative solubility of various gases at -40°C is shown in the table below: Relative solubility of various gases in methanol at -40°C. Gas | Solubility in methanol / Solubility of H2 | Solubility in methanol / Solubility of CO2: H2S – 2540; 5.9; COS – 1555; 3.6; CO2 – 430; 1.0; CH4 – 12; CO – 5; N2 – 2.5; H2 – 1.0. When CO2 is present in the gas mixture, the solubility of H2S in methanol is reduced by approximately 10% to 15% compared to when there is no CO2 present. The higher the CO2 content in the solution, the more significant the decrease in the solubility of H2S in methanol. When H2 is present in the gas, the solubility of CO2 in methanol decreases. When methanol contains moisture, the solubility of CO2 also decreases; when the moisture content in methanol is 5%, the solubility of CO2 in it is about 12% lower compared to anhydrous methanol. As for the system pressure, it depends on the pressure of the entire methanol plant
Hello, on the third floor. Could you explain in more detail what you mean by the relative solubility of gases? Could you give an example? Does it mean that if the solubility of methanol in H2 is 1, then its solubility in CO2 is 430? Is the solubility of CO2 in methanol-rich solution with 1 mol of H2 dissolved equal to 430? Also, [when there is CO2 in the gas, the solubility of H2S in methanol is reduced by about 10%~15% compared to when there is no CO2]. The higher the CO2 content in the solution, the more significant the decrease in the solubility of H2S in methanol. When H2 is present in the gas, the solubility of CO2 in methanol decreases. When methanol contains moisture, the solubility of CO2 also decreases; when the moisture content in methanol is 5%, the solubility of CO2 in it is about 12% lower compared to anhydrous methanol. As for the system pressure, it depends on the pressure of the entire methanol plant. Where did you find this information? Could you share it?
I don’t think this absorption rate is a key factor in designing an absorption tower! The operating pressure of the absorption tower is determined by the vaporization pressure; the better the specified pressure drop, the better. It also depends on the inherent pressure drop of the designed tower and the pressure difference at the inlet. 1. No matter what you produce, H2S must be removed cleanly from the lower column ； So the removal rate should be 100%. 2. The CO2 content in the process gas exiting the tower is determined based on your downstream processes; it needs to be removed completely if producing ammonia, while 2.5% should be retained if producing methanol ； This removal rate should be known even without being mentioned. Regarding the operating temperature of the absorption tower, there is a material balance sheet available at http://bbs.hcbbs.com/viewthread.php?tid=374887&highlight=; you can refer to it!
Agreed. The absorption rate depends mainly on the composition of the feed gas and the requirements of subsequent processing stages regarding that composition. Here, it is necessary to consider the purification standards for CO2 and H2S at the outlet point before calculating the absorption rate. I saw a post by Haiyou stating that in the methanol synthesis process, the CO2 concentration in the purified gas should be below 4%; so what should be the standard for H2S?