Modeling of CO 2 Capture with Water Bubble Column Reactor

The demand for carbon capture is increasing over time due to rising CO 2 levels in the atmosphere. Even though fossil emission could be decreased or even eliminated, there is a need to start removing CO 2 from the atmosphere. The removed CO 2 could be either stored permanently to a reservoir (CCS, Carbon Capture and Storage) or utilized as a raw material in a long-lasting product (CCU, Carbon Capture and Utilization). The capture of CO 2 could be done by direct air capture, or capturing CO 2 from biogenic sources. Amine absorption is the state-of-the-art method to capture CO 2 , but it has some drawbacks: toxicity, high heat demand, and sorbent sensitivity towards impurities such as sulfur compounds and degradation in cyclic operation. Another potential solvent for CO 2 could be water, which is easily available and safe to use in many applications. The problem with water is the poorer solubility of CO 2 , compared with amines, which leads to larger required flow rates. This study analyzed the technical feasibility of water absorption in a counterflow bubble column reactor. A dynamic, one-dimensional multiphase model was developed. The gas phase was modeled with plug flow assumption, and the liquid phase was treated as axially dispersed plug flow. CO 2 capture efficiency, produced CO 2 mass flow rate, and the product gas CO 2 content were estimated as a function of inlet gas and liquid flow rate. In addition, the energy consumption per produced CO 2 -tonne was calculated. The CO 2 capture efficiency was improved by increasing the liquid flow rate, while the CO 2 content in product gas was decreased. For some of the studied liquid flow rates, an optimum gas flow rate was found to minimize the specific energy consumption. Further research is required to study the integration and dynamical operation of the system in a realistic operation environment.