Computational Modeling for Multicomponent Separation of Volatile Organic Compounds by Sorption

摘要

Volatile organic compounds (VOCs) comprise the majority of "Hazardous Air Pollutants" (HAPs) emitted into the atmosphere by major industrial sources. These emissions have generated a noticeable negative impact on air quality. Since an elimination of the VOC HAPs at the source may not be a feasible short-term solution, many industries need to use cost-effective exhaust flue gas treatment technologies to reduce their emissions. Adsorption is one of the effective processes that are used as treatment technologies to separate the VOCs for reuse or combustion heat recovery. Design and development of the new sorption technologies requires characterization of the proposed novel processes and systems. Many of the new treatment solutions are required for multicomponent VOC flue gas mixtures. Design of the new multicomponent VOC treatment systems requires sorption characteristics data. Extensive capital and labor are needed to obtain the multicomponent adsorption characteristics data by laboratory experiments. As a substitution for laboratory characterization experiments, this paper presents a computational approach for modeling multicomponent VOC sorption equilibrium and non-equilibrium processes in fiber adsorbents. The model is capable of predicting gas and fiber phase temperatures and concentrations of VOC components under different adsorption and desorption conditions. A preliminary sample of results for single component sorption is provided. "Thermal Equation of Equilibrium Adsorption" (TEEA) introduced by Hueckel in 1928 and Dbinin-Astakhov models are revisited and modified to provide a predictive model capable of determining VOCs single component equilibrium adsorption thermodynamics in microporous adsorbents. The adsorption affinity factor, determined from dispersion interaction theory, enables the DA-TEEA along with "Ideal or Real Adsorbed Solution Theories" (IAST/RAST) to predict multicomponent adsorption equilibrium characteristics of VOCs from adsorption equilibrium data of a similar reference adsorbate. Predicted adsorption capacities should be accurate well in the range acceptable for engineering design and development purposes. The modified DA-TEEA/IAST model is used to model binary adsorption of acetone and benzene in Kynol ACC-5092-20 from single component acetone adsorption data. The DA-TEEA/IAST provides high-accuracy results. It is also shown that the Henry's law pressure range is the limiting factor for accuracy of the modified DA-TEEA/IAST model.