Aspen is used to query the gas-liquid phase equilibrium curves of mixtures
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To design a packed tower, it is necessary to know the minimum liquid-to-gas ratio, and the minimum liquid-to-gas ratio in turn requires the gas-liquid equilibrium curve. I have been recently simulating the absorption of CO2 by MDEA-PZ solutions, but I couldn’t find the gas-liquid phase equilibrium curves for this system (I’m not sure where such data can be found, or if there are any relevant links). Therefore, I want to use Aspen to carry out the calculations. What I would like to ask now is: I selected the \"Mixtures\" option under \"Analysis\" on the \"Material Properties\" interface, then chose the components and flow rates, specified the pressure and temperature, using the CO2 partial pressure as the variable. MOLECONC was selected for the physical property group. Are the results obtained from this analysis those of gas-liquid phase equilibrium? Also, since the inlet conditions are known when designing the absorption tower, the flow rate of the absorbing liquid is still unknown; can any appropriate value be entered for it? Will it have an impact if the liquid flow rate designed later is different from this one?
First, by selecting “Analysis” -> “Mixtures” in Aspen Properties, choosing the components and flow rates, and specifying the pressure and temperature, the results obtained with the CO2 partial pressure as the variable are not precise gas-liquid phase equilibrium data. This method calculates the properties of a mixture by estimating the physical and chemical properties of its components using thermodynamic models. If you want to obtain accurate gas-liquid phase equilibrium curves, consider using experimental data or software tools based on thermodynamic models. Secondly, you can specify the flow rate of the absorbent solution as you wish. When designing a packed tower, determining the minimum liquid-to-gas ratio may require fixing the liquid flow rate; however, when exploring gas-liquid phase equilibrium, you can try using different absorbent flow rates to obtain various parameter values. The liquid flow rate determined in subsequent designs may differ from the absorbent flow rate you entered earlier, which could affect the design and operation of the packed tower; therefore, updates and adjustments are necessary. .
Okay, thank you. Can the gas-liquid equilibrium data obtained using the Aspen method generally be used as a reference for the design of packed towers? Because experimental data for this system is hard to find. Or which other software provides a more accurate simulation?
You can use the Aspen method to obtain preliminary gas-liquid equilibrium data as a reference for the design of packed towers, but it should be noted that the results obtained from this method usually differ to some extent from the actual experimental data. Therefore, it is recommended to use more accurate methods for verification and optimization before proceeding with the final design. In the chemical engineering field, there are other software tools available for simulating gas-liquid phase equilibrium, such as ProSim and ChemCAD. These software programs typically feature more accurate thermodynamic models and gas-liquid phase equilibrium models, enabling them to provide more precise results. It should be noted, however, that these software programs often require higher technical skills and an academic background, and their use demands more expertise and experience. .