$\mathrm{C}{\mathrm{O}}_2$ Capture from Flue Gases Using Three Ca-Based Sorbents in a Fluidized Bed Reactor

Experiments of $\mathrm{C}{\mathrm{O}}_2$ capture and sorbent regeneration characteristics of limestone, dolomite, and $\mathrm{Ca}\mathrm{O}∕{\mathrm{Ca}}_{12}{\mathrm{Al}}_{14}{\mathrm{O}}_{33}$ at high temperature were investigated in a thermogravimetric analyzer (TGA) and a fluidized bed reactor. The effect of reactivity decay of limestone, dolomite, and $\mathrm{Ca}\mathrm{O}∕{\mathrm{Ca}}_{12}{\mathrm{Al}}_{14}{\mathrm{O}}_{33}$ sorbents on $\mathrm{C}{\mathrm{O}}_2$ capture and sorbent regeneration processes was studied. The experimental results indicated that the operation time of high efficient $\mathrm{C}{\mathrm{O}}_2$ capture stage declined continuously with increasing of the cyclic number due to the loss of the sorbent activity, and the final $\mathrm{C}{\mathrm{O}}_2$ capture efficiency would remain nearly constant, due to the sorbent already reaching the final residual capture capacity. After the $\mathrm{C}{\mathrm{O}}_2$ capture step, the Ca-based sorbents need to be regenerated to be used for a subsequent cycle, and the multiple calcination processes of Ca-based sorbent under different calcination conditions are studied and discussed. Reactivity loss of limestone, dolomite and $\mathrm{Ca}\mathrm{O}∕{\mathrm{Ca}}_{12}{\mathrm{Al}}_{14}{\mathrm{O}}_{33}$ sorbents from a fluidized bed reactor at both mild and severe calcination conditions was compared with the TGA data. At mild calcination conditions, TGA results of sorbent reactivity loss were similar to the experimental results of fluidized bed reactor for three sorbents at $850°\mathrm{C}$ calcination temperature, and this indicated that TGA experimental results can be used as a reference to predict sorbent reactivity loss behavior in fluidized bed reactor. At severe calcination condition, sorbent reactivity loss behavior for limestone and dolomite from TGA compare well with the result from a fluidized bed reactor.