High-pressure Adsorption Equilibria Aimed at Optimizing Sour Gas Conditioning
Date
2019-04-24
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Abstract
In Canada, adsorbents are used to dehydrate high-pressure sour gases containing large concentrations of H2S and CO2, e.g., Grizzly Valley, BC. Glycol dehydration is preferred when dehydration occurs at a gas processing facility, but adsorbents are often utilized for well-site dehydration where the advantages are minimal pressure drop and water dewpoint control before transportation. This research looks to add fundamental adsorption measurements and multicomponent adsorption calculations, while elucidating known issues and increasing efficiency for adsorptive dehydration of sour gas at large pressures. Adsorptive dehydration of sour gas uses a fixed-bed dehydration process, with closed-cycle thermal regeneration. Zeolite and silica gel have a relatively high affinity for H2O and are common choices for these systems. However, strong H2O adsorption results in high-temperature thermal regeneration, which can potentially over-dry the sour natural gas, cause advanced degradation of the adsorbent bed and/or catalyze unwanted reactions. For example, the equilibrium reaction of CO2 and H2S to form COS and H2O is more favourable in hot-dry conditions, which occurs during the thermal regeneration stage of this process. Optimizing thermal regeneration temperatures and wet-gas regeneration of adsorbents can open avenues for minimizing energy requirements and COS production, which can lead to significant cost savings. Unfortunately, the self-consistent adsorption data did not exist for sour natural gas at production pressure prior to this work. To bring self-consistent experimental adsorption data into the open literature three custom-built adsorption apparatus were used for the measurement of pure adsorption capacities of CH4, CO2, COS, H2S, H2O on zeolite 3A, 4A, 13X and a selected silica gel. The measured pure-component adsorption data forms the basis of a multicomponent calculation, which has been subsequently tested experimentally using multicomponent adsorption experiments at well-site pressures. The multicomponent calculation method is used to simulate a fixed-bed dehydration process using closed-cycle thermal regeneration, where optimizing regeneration conditions could increase energy efficiency, adsorbent lifetime and decrease unwanted side reactions.
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Adsorption
Citation
Wynnyk, K. G. (2019). High-pressure adsorption equilibria aimed at optimizing sour gas conditioning (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.