For multi-stage absorption towers, how should the concentration of the absorbent solution be determined?
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Hello everyone. Our facility uses a process involving sodium hydroxide to absorb hydrogen sulfide, with multi-stage packed towers. To improve the efficiency of using the alkaline solution, we plan to adopt a strategy of increasing the concentration of the alkaline solution over time: high-concentration alkali is used for absorption at the initial stages, and once the pH level drops, the solution is sent to the subsequent towers for further use. Is this a good design? Is it better to increase or decrease the alkali solution concentration? What materials are available for reference? Thank you
Everyone, share your opinions. Thank you!
Personally, I think it’s due to the backflow of hydrogen sulfide and alkaline solution; concentrated alkali is used in the last stage to ensure that the exhaust emissions meet the standards
Isn’t the alkali solution the same in the first stage? At the final stage, a lot of concentrated alkali is carried away along with the exhaust gases; I think it’s a waste. This is just a beginner’s understanding – please forgive any mistakes. Are there any design documents related to this topic? Thank you
Generally, counterflow results in a larger contact surface area, leading to better absorption
Generally, for such contact adsorption, the counter-current adsorption method is employed. Its principle is similar to that of counter-current heat exchange in heat exchangers: by increasing the contact area and contact time, a good absorption effect can be achieved. It is better to adopt a decreasing approach for the alkali solution concentration; a higher initial concentration allows for the absorption of most of the hydrogen sulfide, while the concentration in subsequent stages will be lower if ideal conditions are achieved. Using an alkali solution with a lower concentration later on can also achieve good absorption results, and it avoids waste resulting from the alkali solution being carried out of the equipment (even if some alkali solution is carried away with the exhaust gases, the concentration of that solution is low)
Generally, alkali is added in the last stage for desulfurization; therefore, a counter-current configuration is preferable to ensure an excess of alkaline solution in that final stage.
Hello, we have well-developed technical solutions for various processes related to the production of sulfur, hydrogen, and sodium hydroxide. I’m not sure what your product is; if you need any assistance, please contact Tangshan Lvyuan Environmental Protection at Q418248382