CCS and Power Systems
Carbon Capture - Post-Combustion Capture
Combined Pressure, Temperature Contrast and Surface-Enhanced Separation of Carbon Dioxide for Post-Combustion Carbon Capture
Performer: William Marsh Rice University
Project No: FE0007531
Rice University will develop a novel gas absorption process for CO2 capture that is projected to have considerably lower capital and operating costs than the conventional monoethanolamine process. The unique process combines the absorber and desorber columns, separated by a microporous ceramic membrane, into a single integrated unit. Conventional CO2 capture processes consist of a column that absorbs CO2 with a liquid solvent, and a separate column that desorbs CO2 from the solvent. Researchers at Rice University have determined that it is possible to integrate the absorber and desorber sections into a single unit. The integrated absorber/desorber arrangement will reduce space requirements, an important factor for retrofitting existing coal-fired power plants with CO2 capture technology.
This novel capture process uses ceramic foam contactors with complex, highly-interconnected structures for the absorption and desorption of CO2. The ceramic gas-liquid contactors have favorable characteristics for mass transfer with large geometric surface areas, up to ten times that of conventional packing. Additionally, the contactors will be chemically functionalized to enhance the absorption and desorption processes. The resulting functionalized packing is anticipated to increase the rate of CO2 absorption into the solvent, making it feasible to use slow-reacting amines with low heats of regeneration. Commercially available solvents with well-documented performance will be examined. In the integrated unit, a microporous ceramic membrane allows for selective permeation of the CO2-rich liquid from the absorber section through the membrane and into the CO2 desorbing side. The desorber section is operated under a moderate vacuum to separate the CO2 from the solvent at reduced temperatures, which provides the cost-saving advantage of using low-grade heat from the plant.
Rice University will perform an initial analysis to estimate the technical and economic feasibility of the process. A bench- scale prototype will then be developed to implement the complete CO2 separation process and tests will be conducted to study various aspects of fluid flow in the process. A model will be developed to simulate the two-dimensional (2-D) fluid flow and optimize the CO2 capture process. Test results will be used to develop a final techno-economic analysis and identify the most appropriate absorbent as well as optimum operating conditions to minimize capital and operating costs. This analysis will indicate the feasibility of integrating the process into a 550 megawatt electric (MWe) coal-fired power plant. An environmental, health, and safety (EH&S) assessment of the capture process will also be completed.