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Many friends have discussed with me the issue of simulating absorption towers; it seems that Aspen Plus has difficulty converging when used for such simulations. In this document, I will carry out a detailed simulation of the absorption of H2S and CO2 from sulfur-containing natural gas using MDEA as the absorbent, in the hope of providing some assistance to everyone working on the simulation of absorption towers! Title: Treatment of sulfur-containing natural gas using MDEA solvent to achieve acceptable sulfur content: Gas feed temperature is 40°C, and pressure is 1.2 atm ； The solvent feed temperature is 25°C, and the pressure is 1.2 atm ； The total pressure drop across the tower is 0.1 atm. Composition of the MDEA absorbent: (The initial feed amount can be determined empirically.) Mass concentration of the absorbent: 8%. Composition of the sulfur-containing natural gas: Mole fractions of components/% CH4: 13.49; H2S: 15.11; CO2: 18.2687; N2: 9.99519; O2: 3.12512; H2: 4.96061; CH4S: 0.048224; C2H6S-2 (dimethyl sulfide): 0.0123922; H2O: 11.9343. Requirement: The sulfur-containing natural gas must be treated so that the H2S content in the treated gas is below 20 mg/cum. Before conducting the simulation, it is necessary to understand the overall approach to be taken in order to carry out the simulation properly: A detailed simulation is carried out using the Radfrac module, while parameter optimization is achieved through sensitivity analysis. The simulation process is as follows: Step 1: Select the “kmdea” template from the electrolyte process data package; using this template for simulation can save a lot of trouble. However, in this case it is still necessary to manually add organic compounds such as methane, ethane, propane, and isobutane, as well as the Henry components. We use amine packages, which contain built-in kinetic data that is important for the accuracy of the simulations. However, in Reactions it is not possible to add two different kinetic models at the same time; instead, they must be combined into one (make sure there is no duplication). Step 2: Conduct a preliminary simulation using the Radfrac module. Enter the parameters of the feed stream. Gas feed parameters: Absorbent feed parameters: Since the exact amount of absorbent required is unknown, it is temporarily set to 80,000 kg/h here; the optimal amount of absorbent can be determined later through parameter optimization. Enter the module parameters: First, set the number of absorption tower plates to 10; for the condenser and reboiler of the absorption tower, select None. Next, specify the location where the fluid feed enters the system. Finally, set the pressure at the top of the tower to 1.0 atm – this final pressure can be determined through parameter optimization. We know that this is a simulation of a chemical absorption process, and kinetic parameters are provided in the amine package; therefore, chemical reactions and the liquid holdup should be added under “Reactions”, as shown in the figure below. Since we are simulating an absorption tower, the following settings are required: set Absober tower to “Yes”. Step 3: Run the process simulation and check the information on the control panel. When the process ends, it indicates that we lack the Henry’s law parameter among the binary interaction parameters, which needs to be entered manually. Running it again results in convergent outcomes. Step 4: Parameter optimization. First, we need to meet the requirements specified in the problem, namely to keep the H2S content in the outlet gas below 20 mg/cum. This can be achieved by optimizing the amount of absorbent used through appropriate design considerations. The settings are as follows: The results are as follows: The feed flow rate is modified again, followed by optimization of the absorbent feed temperature and the top pressure of the tower: (1) Optimization of the absorbent feed temperature: First, the parameters are set; the results are then examined. Based on the results, it can be seen that a temperature of 25 degrees Celsius at room temperature is sufficient to achieve the desired effect; therefore, the absorbent is fed at 25°C. (2) Optimization of the top pressure in the absorption tower: First, parameter setting is carried out; then the results are examined. Based on the plots generated from these results, it can be seen that the best performance is achieved when the top pressure of the absorption tower is 1.01 atm. That’s all there is to know about the simulation of absorption towers. The author of this article is still a college student; please feel free to offer your criticism and suggestions! ! !