Stripping Regeneration Research Articles

Desulfurization of Diesel Using Ionic Liquids: Process Design and Optimization Using COSMO-Based Models and Aspen Plus.

Sulfur dioxide emissions from fossil fuel combustion have been known to cause detrimental health and environmental effects. The currently used hydrodesulfurization (HDS) method employed by refineries has several drawbacks, such as excessive hydrogen consumption, high energy demand, and inability to remove complex organosulfur compounds, which have limited its ability to produce ultralow sulfur diesel (ULSD) at reasonable operating and capital costs. Ionic liquids (ILs) have been widely studied for their potential to replace conventional HDS. However, while their success has been demonstrated at the laboratory level, studies on industrial-scale feasibility and their integration into process simulators such as Aspen Plus are limited. In this work, 26 commercially available ILs have been screened using COSMO-based models and Aspen Plus for the desulfurization of diesel fuel and several possible process configurations have been examined. In particular, the challenge of ionic liquid regeneration, which has largely been ignored in the literature, has also been addressed and several potential regeneration methods have been proposed including extractive regeneration (E-RE) and stripping regeneration using nitrogen and air as stripping media (S-RE). The results indicate that, among the 26 ILs studied, 1-butyl-3-methylimidazolium thiocyanate is the most promising as a solvent for extractive desulfurization (EDS), E-RE, and S-RE. E-RE was found to be more effective for the removal of dibenzothiophene (DBT), while S-RE is more suited to the removal of thiophene and benzothiophene (BT). As a result, an optimized diesel desulfurization process using 1-butyl-3-methylimidazolium thiocyanate has been proposed that achieves ULSD with <10 ppm total sulfur in simulation studies, with complete recycling of the IL and minimal loss of the model diesel.

Carbon Dioxide Capture by Chemical Solvents Based on Amino Acids: Absorption and Regeneration

AbstractThe use of sodium salts of aqueous solutions of different amino acids (glycinate and prolinate) for carbon dioxide (CO2) separation by chemical absorption is analyzed in a bubble‐column reactor under different experimental conditions of solvent concentration and gas flow rate. The differences in absorption rate and reaction mechanism caused by the presence of carboxylic groups in comparison to the case without (monoethanolamine and pirrolidine) are evaluated. Glycinate solvent reaches a similar behavior than monoethanolamine aqueous solutions but with a higher destabilization of carbamate that allows to increase CO2 loading. Prolinate exhibits a similar behavior than pirrolidine at low CO2 loadings. Both solvents show a significant reduction in absorption capacity when stripping regeneration is carried out.

Evaluation of Process Variables in a Stripping/Regeneration Process Using the Experimental Design Methodology

A spray tower was used to strip the water vapor from the dilute solutions in this study. The role of each operating parameter and its relationship in this stripping/regeneration (ST/RE) process are still unknown. To improve the ST/RE process and elucidate the relationship between the process variables, an experimental design methodology was used to evaluate the process variables of the ST/RE process. A second-order polynomial model with a multiple linear regression to estimate the model coefficients of the five selected factors (process variables) was proposed to study the influence of the factors on the mass transfer coefficient response in the ST/RE process. Only 32 (or 25) experimental runs were necessary to assess these variables and the model satisfied the process very well since the coefficient of determination (R2) was very close to one. The analysis of the mass transfer performance with these experimental data was also reported in this study.