Abstract:
The increase of carbon dioxide (CO2) emissions to our atmosphere is the major contributor to global climate change. A number of methods for reducing greenhouse gases have been proposed including carbon capture and sequestration (CCS). There are three major approaches for CCS post-combustion capture, pre-combustion capture, and oxyfuel process. Post-combustion capture offers some advantages as existing combustion technologies can still be used without radical changes on them. This makes post-combustion capture easier to implement as a retrofit option (to existing power plants) compared to the other two approaches. Currently, the reactive absorption of CO2 into amine solvents is the most widely used technology for CO2 capture. One of the many potential solvent candidates is potassium carbonate (K2CO3). Although potassium carbonate is associated with lower cost, less toxicity and is less prone to degradation effects when compared to the current industrial benchmark solvent, monoethanolamine (MEA), it has a low rate of reaction resulting in poor mass transfer performance. Developing a non-toxic and affordable promoter will facilitate the use of potassium carbonate solvent systems for CO2 capture. Comprehensive flow sheet models have been built for each of the solvent systems, using aspen plus as the modeling tool. Using aspen plus simulation for the reaction kinetics of CO2 into DEA, unprompted and DEA-promoted potassium carbonate (K2CO3) solutions have been studied. The investigation of the CO2 absorption rate comes out with a clear increase in the CO2 absorption with the increases of the process pressure. On the other hand, the absorption rate decreases with the increases of the process temperature. the results presented here show that at 80oC the addition of small amounts of DEA (1%, 2%, and 3%) accelerate the overall absorption process of CO2 in carbonate solvents by 1.63%, 3.26%, and 4.87% respectively. Furthermore, the investigation of the promoter concentration effects showed a sudden declining in the absorption rate for concentrations greater than 4% for the reason of the involving promoter in the main interaction as an additional solvent. Absorption column has been designed to capture carbon dioxide in this research.
