One-dimensional model of entrained-flow carbonator for CO2 capture in cement kilns by Calcium looping process

Abstract In this work, a 1D model of an entrained-flow carbonator of a Calcium looping process for cement plants is presented and the results of a sensitivity analysis on the main governing process parameters is discussed. Several design and operating parameters have been investigated through a wide sensitivity analysis, namely: adiabatic vs. cooled reactor, high gas velocity gooseneck reactor vs. low velocity downflow reactor, solid-to-gas ratio, sorbent capacity, reactor inlet temperature and solids recirculation. The effect of these design and process parameters on the CO 2 capture efficiency and on Calcium looping process heat consumption is assessed. The results of the calculations showed that with a proper combination of solid-to-gas ratio in the carbonator and sorbent carbonation capacity (e.g. ∼10 kg/Nm 3 and ∼20% respectively), carbonator CO 2 capture efficiencies of about 80% (i.e. total cement kiln CO 2 capture efficiencies higher than 90%) can be obtained in a gooseneck-type carbonator with a length compatible with industrial applications in cement kilns (∼120 to 140 m). Further experimental investigations on this reactor concept, especially about fluid-dynamic behavior and the chemical properties of raw meal as CO 2 sorbent, are needed to demonstrate the technical feasibility of the proposed process.