Simulation of Glycol Processes for CO2 Dehydration

Abstract

Water must be removed from CO2 prior to transport or storage to avoid corrosion and hydrate formation. Absorption into triethylene glycol (TEG) followed by desorption is the traditional gas dehydration method, and is expected to be the preferred method for large scale CO2 dehydration. There is no agreement on the level of accepted water content after dehydration, and the specifications vary normally in the range between 5 and 500 ppm (parts per million by volume). In literature, it is claimed that use of solid adsorbents is necessary to reduce the water content to below 30 or 10 ppm. In this work, simulations in Aspen HYSYS demonstrate that it is possible to obtain below 1 ppm water using a traditional glycol dehydration process including an extra stripping column. The models Peng-Robinson (PR) and Twu-Sim-Tassone (TST) with updated parameters in Aspen HYSYS version 8.0 are used. A Drizo process using a stripping gas which is later condensed and recirculated is also simulated, and this process also achieves a water content below 1 ppm in dehydrated CO2.