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Ethane Recovery from Residue Gas Using Pressure Swing Adsorption
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- Author / Creator
- Estupinan Perez, Libardo
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Separation of ethane and heavier hydrocarbons from natural gas stream is a major topic in petrochemical industry due to the increase in Natural gas reserves in North America. Natural gas liquids are frequently separated using a cryogenic distillation process, which is able to separate all the C3+ hydrocarbons and is able to recover 90-97\% of C2. Usually, the trace composition of ethane in the residue gas was not recover but with the increasing demand for ethane as chemical feedstock for the ethylene production, the recovery of this dilute fraction has become important in industry and academia. In this context, pressure swing adsorption is an attractive separation process to achieve the target. The aim of this thesis is the design of a PSA process for the separation of ethane from residue gas. To achieve this, experimental measurements, modeling and optimization tools are developed to characterize the adsorbents, define the cycle configuration, and find the optimal operating conditions for the process. Adsorbents from two different classes were chosen, namely, titanosilicates and activated carbons. Experimental isotherm data was obtained in-house for all of them. Subsequently, the experimental data was fitted to an isotherm model and further, heat of adsorption was determined to complete the adsorbent characterization. A rigorous one-dimensional model that takes into account mass, momentum, and heat balances and several constitutive equations such as pressure drop, adsorption isotherms, and equation of state for the gas phase is developed to simulate adsorption the adsorption process. Three different cycle configurations are proposed to achieve the separation. To compare their performance, C2 purity and recovery are used as performance metrics. Using standard operating conditions, cycle configurations are compared and through a parametric study, the effect of feed temperature and heat effects are completely described. A multi-objective optimization, based on an evolutionary algorithm, using C2 purity and recovery as objective function is developed to obtain three important insights for the process developments: the adsorbent with the best performance, the most suitable cycle configuration, and the optimal operating conditions. The results from the optimization are analyzed using Pareto fronts in terms of the objective function and a full description of the process is obtained.
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- Graduation date
- Spring 2015
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.