| Abstrakt: |
Alstom is a pioneer and industrial leader in the development of post combustion CCS technologies. Alstom's Regenerative Calcium Cycle (RCC) is a 2 nd generation post combustion CCS technology utilizing a calcination/ carbonation loop to capture CO 2 from flue gas at high temperatures. The CO 2 capture cycle is driven by introducing heat required to regenerate sorbent at 900 °C (4.0 GJ/t CO 2 , chemically bound CO 2 ) the regenerated sorbent is then used for CO 2 capture from flue gas where the exothermic heat of the reverse reaction (-4.0 GJ/t CO 2 captured) is recovered in a power cycle. Due to the option of using natural sorbent materials (limestone), RCC also provides attractive integration opportunities with industrial processes such as cement production. Recently indirectly fired RCC calcination concepts also open the door for game changing performance gains using natural or even synthetic materials. However, the wide range of performance variability characteristic of natural sorbents contributes to uncertainty in defining process performance. Reliable sorbent deactivation models, which describe both cyclic and chemical deactivation, in combination with mechanistic reactor models which predict gas and solids phase conversions are required to lower the uncertainty associated with new reactor concepts and larger geometries required for commercialization for retrofit power-plant flue gas or for integrated solutions for the cement industry. Parallel to RCC process development, Alstom is currently executing a “Derisking” or risk-mitigation study for Norcem, a Norwegian cement producer, who seeks to take a leading position in the development of technologies for CO 2 -capture from cement production facilities. Norcem is currently heading up a project on behalf of the European cement industry (partners are Norcem, HeidelbergCement and the European Cement Research Academy) investigating various technological options at the pilot scale. In relation to this project, Alstom's RCC technology was selected with the objective to define process performance and the associated uncertainty. Pilot testing was conducted at the Institute of Combustion and Power Plant Technology at the University of Stuttgart (IFK) planned by Alstom focusing on the validation of process models and less the targeting of pilot plant performance, which is often limited by reactor geometries. This paper discusses the characterization of sorbent performance and the gap between the performance expected from thermo- gravimetric analysis (TGA) and that realized during steady state pilot testing under representative operating conditions. Operational stability, material balance closure and the confirmation of sorbent attrition characteristics from pilot testing are also discussed and steady-state operational data, gained from pilot testing are applied to initialize mechanistic process models which allow prediction of reactor performance for larger more efficient designs. [ABSTRACT FROM AUTHOR] |
