A simulation study of reducing carbon dioxide and hydrogen sulfide adsorption in dehydration beds

Abstract

In natural gas dehydration units, a problem that may arise is the increased concentration of carbon dioxide and hydrogen sulfide in their feed. During the adsorption stage, these gases are adsorbed along with water by the dehydration bed. During the regeneration stage, these adsorbed gases are desorbed from the bed. Their presence along with water and high temperatures causes the equipment and pipes in the regeneration path to corrode. Therefore, minimizing the adsorption of these gases in dehydration beds is imperative. Based on simulations of Aspen Adsorption, three solutions have been described and investigated in this article. The first solution is using 3 A adsorbent which has a lower adsorption capacity for carbon dioxide and hydrogen sulfide than other adsorbents like 4 A. But this adsorbent also has a lower adsorption capacity for water, so the first solution needs more cycles for the gas dehydration process. This reduces the adsorbent lifetime. Increasing the duration of the adsorption stage is the second solution. This solution has little effect and cannot solve the problem. The third solution is layering the dehydration bed with different adsorbents. This solution can reduce carbon dioxide and hydrogen sulfide adsorption by 48.7% and 49.9%, respectively, when 3 m of 3 A adsorbents are used at the bottom and 3.5 m of 4 A adsorbents are used at the top of the bed.