Optimum Adsorbent-Process Combination for Minimum Cost Carbon Capture Using a VSA Process

Vacuum Swing Adsorption (VSA) is one of the competing technologies being explored for carbon capture and concentration (CCC) from power plant flue gas. We have developed a simulation and optimization platform for CCC by VSA operated on different cycles. This platform has been used to evaluate energy-productivity performance of various adsorbents in order to identify the most favorable adsorbent-cycle combination. Energy and productivity are important determinants of the operating and capital costs of a VSA process. However, their relative share in the overall cost depends on the VSA cycle and its operating conditions in a complex way. Hence ranking adsorbents based on the energy-productivity performance may be very misleading.

Here, we have expanded our optimization platform to incorporate all the steps necessary to carry out detailed costing of a VSA process. The scope of the simulation and optimization platform is further expanded to include adsorbent isotherm characteristics, in addition to the process operating conditions, as decision variables. These expansions allow integrated adsorbent-process optimization including detailed costing. Thus we are able to find the minimum capture cost possible in a VSA process for CCC and at the same time determine the corresponding optimum adsorbent isotherm characteristics. We have answered these questions for two VSA cycles, namely a 4-step process with light product pressurization (LPP) and a 6-step process with light and heavy reflux in addition to LPP.