Flue gas absorption in the diammonium phosphate production process
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Regarding the exhaust gases generated in the diammonium phosphate production process, is it more effective to use phosphoric acid for absorption – dilute phosphoric acid or concentrated phosphoric acid? And why? This is a question from the doctoral entrance exam in chemical engineering principles; someone asked me about it and I didn’t understand it, so I’m seeking advice from everyone. Original question: Ammonia in the exhaust gases from the process of producing diammonium phosphate is absorbed using phosphoric acid. Apply the double-membrane theory to analyze the control steps in this process Is it easier to remove ammonia using concentrated phosphoric acid as an absorbent than using dilute phosphoric acid? Why? 10 points】
The double-membrane theory will not be applied for analysis; however, from a practical production perspective, dilute phosphoric acid seems to be more effective than concentrated phosphoric acid at absorbing ammonia from exhaust gases.
I really don’t know the answer to this question. We used to use concentrated acid for cleaning, but we’ve been trying diluted acid recently; concentration is the bottleneck
For our production, what type of acid washing to use is one aspect, while the performance of the cleaning nozzles is crucial.
It seems that this purely theoretical stuff is a bit difficult; I didn’t do well in \"Principles of Chemical Engineering\" back then and only managed to pass.
This is itself a chemical absorption process, and gaseous ammonia is also highly soluble; therefore, if the enhancing effect of chemical reactions is not taken into account, according to the double-membrane theory, the mass transfer resistance should lie on the gas-phase side, meaning it is governed by the gas phase membrane. Generally speaking, increasing the gas flow rate can thin the thickness of the gas film layer and reduce the resistance to mass transfer in the gas phase, thereby increasing the absorption rate; this has little to do with the liquid ； If chemical reactions are taken into account, the absorption enhancement factors can vary depending on the speed of the reactions, which makes the discussion more complex
5th floor, SCU2000. Does SCU refer to those who graduated from Sichuan University? If that’s the case, take a close look at the new edition of \"Principles of Chemical Engineering, Volume 2\" published by Sichuan University; it provides detailed information on the double-membrane theory and also covers chemical absorption to some extent
Analyzed using the double-membrane theory, which is highly theoretical, the absorption process from the gas membrane to the liquid membrane should take into account the mass transfer coefficient of the liquid membrane; undoubtedly, dilute acids yield better reaction results, and in practical applications, dilute acids are indeed used for washing.
It seems the professor has read so many books that he’s become dull-minded; everything is washed with dilute acid – how can the moisture level be balanced?
He indeed graduated from Sichuan University, and the exam questions were also from Sichuan University.
“It seems the professor has read too many books and has become dull-minded; by using dilute acid for washing, how can the water balance be maintained? Since concentrated phosphoric acid (around 48%) is used in the production of diammonium phosphate, the inclusion of dilute washing water in the reaction system allows for proper maintenance of the water balance.