Pilot test results of post-combustion CO2 capture using solid sorbents

Abstract ADA Environmental Solutions (ADA) is examining available sorbents as well as process equipment options to assess the viability and accelerate development of solid sorbents for post-combustion CO2 capture. This work is being completed through a US Department of Energy (DOE) Cooperative Agreement with supplemental funding from ADA, EPRI, and several power industry partners. During the project, sorbents were acquired from 22 developers and screened at the laboratory-scale to select materials for testing in a 1 kW slipstream pilot. Based on the lab scale results, pilot-scale batches of two sorbents were produced and one was tested in the 1 kW pilot. In a parallel effort, commercially available processes and equipment were evaluated to identify those that have promise for commercial-scale CO2 capture. ADA has screened over 100 materials using a fixed bed system both in the laboratory with simulated flue gas and in the field with a slipstream of actual flue gas. The materials were tested over multiple adsorption/regeneration cycles. The purpose of this ongoing screening is to identify materials that exhibit properties that are promising enough to be produced and evaluated at larger scales. Results from different materials are highly varied, but general conclusions can be drawn regarding different sorbent types. For example, sorbents that include amine functionalization generally have a high CO2 capacity (i.e. 5% to 14% by weight), whereas carbon-based materials have been observed to have lower CO2 capacities, but superior cyclic stability. Several hundred pounds of two promising sorbents were produced and evaluated using a contactor installed on a 1 kW equivalent slipstream of flue gas at an operating coal-fired power plant. The system utilizes a circulating fluidized bed with the following key components: adsorption using entrained flow, regeneration via a temperature swing with an option for a sweep gas, gas/solids separation, and cooling. One supported amine sorbent was evaluated in both continuous and batch mode and achieved 90 CO2 removal repeatedly. Many different commercial industries use large-scale equipment for gas/solids contacting, conveying, and heat transfer. In the parallel effort to evaluate commercial-scale equipment options, ADA is working with Stantec, a leading engineering design firm, to identify existing commercial equipment and processes that could be useful for CO2 capture with solids. Each process and/or equipment component has been categorized as being useful for either adsorption, regeneration, materials conveying, and/or heat transfer. A survey has been completed for each potential technology. After examining all of the commercially available technologies, those that are optimal for the application of CO2 capture were selected and used as the basis for a 500 MW conceptual design.