Model based analysis of the post-combustion calcium looping process for carbon dioxide capture

摘要

This thesis presents a one-dimensional, semi-empirical dynamic model for thesimulation and analysis of a calcium looping process for post-combustion CO2 capture.Reduction of greenhouse emissions from fossil fuel power production requires rapidactions including the development of efficient carbon capture and sequestrationtechnologies. The development of new carbon capture technologies can be expedited byusing modelling tools. Techno-economical evaluation of new capture processes can bedone quickly and cost-effectively with computational models before building expensivepilot plants.Post-combustion calcium looping is a developing carbon capture process which utilizesfluidized bed technology with lime as a sorbent. The main objective of this work was toanalyse the technological feasibility of the calcium looping process at different scaleswith a computational model. A one-dimensional dynamic model was applied to thecalcium looping process, simulating the behaviour of the interconnected circulatingfluidized bed reactors. The model incorporates fundamental mass and energy balancesolvers to semi-empirical models describing solid behaviour in a circulating fluidizedbed and chemical reactions occurring in the calcium loop. In addition, fluidized bedcombustion, heat transfer and core-wall layer effects were modelled.The calcium looping model framework was successfully applied to a 30 kWth laboratoryscale and a pilot scale unit 1.7 MWth and used to design a conceptual 250 MWthindustrial scale unit. Valuable information was gathered from the behaviour of a smallscale laboratory device. In addition, the interconnected behaviour of pilot plant reactorsand the effect of solid fluidization on the thermal and carbon dioxide balances of thesystem were analysed. The scale-up study provided practical information on the thermaldesign of an industrial sized unit, selection of particle size and operability in differentload scenarios.