Strategies for CO2 capture from different CO2 emission sources by vacuum swing adsorption technology

Different VSA (Vacuum Swing Adsorption) cycles and process schemes have been evaluated to find suitable process configurations for effectively separating CO2 from flue gases from different industrial sectors. The cycles were studied using an adsorption simulator developed in our research group, which has been successfully used to predict experimental results over several years. Commercial zeolite APGIII and granular activated carbon were used as the adsorbents. Three-bed VSA cycles with- and without-product purge and 2-stage VSA systems have been investigated. It was found that for a feed gas containing 15% CO2 (representing flue gas from power plants), high CO2 purities and recoveries could be obtained using a three-bed zeolite APGIII VSA unit for one stage capture, but with more stringent conditions such as deeper vacuum pressures of 1–3 kPa. 2-stage VSA process operated in series allowed us to use simple process steps and operate at more realistic vacuum pressures. With a vacuum pressure of 10 kPa, final CO2 purity of 95.3% with a recovery of 98.2% were obtained at specific power consumption of 0.55 MJ·(kg CO2)− 1 from feed gas containing 15% CO2. These numbers compare very well with those obtained from a single stage process operating at 1 kPa vacuum pressure. The feed CO2 concentration was very influential in determining the desorption pressure necessary to achieve high separation efficiency. For feed gases containing > 30% CO2, a single-stage VSA capture process operating at moderate vacuum pressure and without a product purge, can achieve very high product purities and recoveries.

Flue gas CO2 concentration differs from different industrial sectors, and hence different VSA cycle configurations are required. A new 13X zeolite-APGIII was compared with coconut carbon to find the better candidate for the VSA. Different VSA cycles and process schemes have been evaluated in order to find suitable process configurations to effectively separate CO2 from flue gas from different industrial sectors, and we also analyze the important processing parameters and the energy consumption for VSA cycle. The goal of this study was to design suitable VSA process configurations to upgrade CO2 concentration in various feed streams to > 95%, at a minimum capture rate of 80%.Figure optionsDownload as PowerPoint slide