Demand for amine-depleted liquid for desulfurization of catalytic dry gas and liquefied gas
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Dear sea friends: Please advise on the method for calculating the demand for desulfurization and amine-depleted liquid for catalytic dry gas and liquefied gas. Taking dry gas as an example, if the gas flow rate is 8,900 standard cubic feet per hour and the mass of hydrogen sulfide is 0.086 tons, based on empirical data regarding the degree of adsorption – 1 mole of methyl diethanolamine can absorb 0.3 to 0.5 moles of hydrogen sulfide (we use 0.4 in this calculation) – and considering that the molecular weight of hydrogen sulfide is 34 while that of methyl diethanolamine is 120, the amount of methyl diethanolamine required is calculated as: Mass of hydrogen sulfide / Molecular weight of hydrogen sulfide * Absorption ratio * Molecular weight of methyl diethanolamine. Thus, the amount is 0.086/34*0.4*120 = 0.121 tons. Assuming a concentration of 33% for methyl diethanolamine, the circulation rate of this substance is 0.121/0.33 = 0.37 tons per hour. However, the actual operation circulation rate is 28 tons per hour (this higher rate is used to ensure effective adsorption). There is a significant difference between these two values; I would appreciate some guidance on this matter. If calculated using the chemical equation CH3N(CH2CH2OH)2 + 2H2S = CH3N(CH3CH2HS)2 + 2H2O, this represents complete absorption, that is, 100%. In practical applications, factors such as operating pressure and tray efficiency must be taken into account. I’m not sure how to carry out the calculations, so I’d like to ask for guidance. Thank you!
Personal opinion, not sure if it’s correct – for reference only: 1. The amount of methyl diethanolamine required = mass of hydrogen sulfide / molecular weight of hydrogen sulfide / absorption ratio * molecular weight of methyl diethanolamine; that is, 0.086/34/0.4*120 = 0.7588 tons. 2. The actual concentration of methyl diethanolamine may not reach 33%, but rather around 25%, which results in a greater need for MDEA. 3. There are issues related to absorption efficiency, such as absorption equilibrium and gas-liquid contact, so complete absorption is not possible. 4. Other factors like the absorption of CO2 also consume MDEA. 5. Generally, there is an optimal ratio between the absorbent liquid and the gas. 6. Therefore, it’s normal for the actual amount of absorbent required to be much higher than the theoretical amount