4. Conclusion
In this study, a general model is proposed to calculate carbon dioxide solubility in amine solutions, which will be used for predicting the properties of the system using the CPA equation of state and TEA and pyrazine water soluble absorbents. The reason for the use of piperazine is that TEA has barriers and disadvantages due to its limited loading capacity and absorption capacity. In recent years, the study has focused on the use of new and optimal materials to absorb acidic gas from natural gas, according to the results and reports of research sources of piperazine, as a trusted enhancer and additive.
The deviation of the predicted values from the experimental data ​​by the simulated model at three operating temperatures of 313, 333, and 353 K were 6.3%, 6.7% and 7.3%, respectively, indicating a lower error reported at the lower temperature due to less complexity of the assumptions and also the modeling conditions are at lower temperatures. By increasing temperature, the amount of carbon dioxide absorbed in the adsorbent solution decreases due to the increased carbon dioxide incidence in the gas phase at higher temperatures. Increasing the temperature reduces the absorption efficiency, and the reason is that the absorption of carbon dioxide by thermally absorbing the ammonia absorbent. With increasing temperature, the gradient of absorption is more lenient and the slower absorption at very high temperatures can be due to the structural changes in the amine absorbent solution or the breakdown of adsorption bonds formed in the adsorption process at higher temperatures. The deviation of the model is also 2.9%, 5.9%, and 7.4%, in comparison with the literature data, at operating pressures of 15, 60 and 110 kPa, which indicates that although high pressure for the reasons above mentioned it improves the absorption conditions, but due to the lower complexity of modeling conditions and assumptions, the reported deviation is lower in lower and moderate pressures. Also, by increasing the concentration of piperazine in the amine absorbent solution, the amount of carbon dioxide absorption increases due to the increased reaction rate of amine solution with carbon dioxide in the presence of piperazine. But in higher concentrations, the increasing trend of absorption of carbon dioxide in the adsorbent solution is due to the increased viscosity of the adsorbent solution due to the excessive increase in the adsorption potential of the piperazine, and the absorption rate will be less incremental due to this. The review and comparison of the model results with available experimental data suggests that the results show good accuracy and proximity to experimental data. So, the simulated model can be used as a reliable model for predicting carbon capture absorption results in a variety of conditions, with less experimental data.