Colloquia

Summary

This thesis presents the findings of a model-development study and a design optimization procedure for a Vacuum Swing Adsorption (VSA) cycle, capable of capturing CO2 from HyGear’s Steam Methane Reforming (SMR) flue gas. A previously developed dynamic VSA model has been improved through the addition of an equalization process, which provides the purity benefits of the common blowdown step without its energy requirement and yield trade-off. A mass balance convergence loop has been used to derive a function for the equalization pressure. As a result, the equalization pressure can be predicted given the adsorbent material and operating pressures. The validated model was used to study several influential parameters in the carbon capture process, namely the duration of individual phases, feed composition, feed velocity, and operating pressures. These variables have been tested using Activated Carbon and Zeolite 13X as adsorbent materials. The final design was evaluated based on three performance indicators: ≥80% recovery, food-grade purity (≥99.999%), and an energy consumption less than 150 kWh/ton CO2. This design is based on a CO2/N2/H2O mixture, with 15% CO2 at the inlet. In practice, the SMR flue gas also contains contaminants as NOx and SOx that need to be taken out prior to the carbon capture process. Hence, complementary purification methods are briefly discussed in the context of future process development. Overall, this study contributes to HyGear’s broader goal of providing sustainable blue hydrogen.