Assessment of the operability of a 20 MWth calcium looping demonstration plant by advanced process modelling

The Calcium Looping (CaL) process is a promising technology for post-combustion CO2 capture from fossil-fired power plants and carbon intense industry. Within a CaL system, a limestone based sorbent stream is forced to circulation between two interconnected circulating fluidized bed (CFB) reactors. The main part of the CO2, contained in the flue gas stream is absorbed by CaO within the carbonator, whereas it is released during regeneration in the oxy-fired calciner. The feasibility of this technology was proven by numerous experimental investigations in semi-industrial scale. The next step in the development of this technology is expected to be a demonstration plant in the scale of approximately 20 MWth. The focus of this paper is the determination of the heat and mass balances and the assessment of the operability of a newly designed 20 MWth CaL demonstration plant. The investigations are based on a steady-state process model, which has been validated by experimental data from 1 MWth pilot tests. The aspect of solid entrainment during part load operation are addressed. In the present design case, a stable operation of the demonstration plant at 40 % equivalent carbonator load is feasible without additional flue gas recirculation.