Ningsheng Cai

CO2 Capture from Flue Gases Using Three Ca-Based Sorbents in a Fluidized Bed Reactor

Experiments of CO2 capture and sorbent regeneration characteristics of limestone, dolomite, and CaO /Ca12Al14O33 at high temperature were investigated in a thermogravimetric analyzer TGA and a fluidized bed reactor. The effect of reactivity decay of limestone, dolomite, and CaO /Ca12Al14O33 sorbents on CO2 capture and sorbent regeneration processes was studied. The experimental results indicated that the operation time of high efficient CO2 capture stage declined continuously with increasing of the cyclic number due to the loss of the sorbent activity, and the final CO2 capture efficiency would remain nearly constant, due to the sorbent already reaching the final residual capture capacity. After the CO2 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 CaO /Ca12Al14O33 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°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.

Design and Cold Mode Experiment of Dual Bubbling Fluidized Bed Reactors for Multiple CCR Cycles

The dual fluidized bed reactors are the key technology to fulfill the multiple CCR (calcination/carbonation reactions) cycles for CO2 capture from the flue gases. Firstly, the dual bubbling fluidized bed reactors were selected in this work based on analyzing different types of dual fluidized bed reactors. Secondly, the design method of dual fluidized bed reactors for CO2 capture with CCR concept was proposed. Thirdly, with the designed results, a cold mode of the dual bubbling fluidized bed reactors was built. The long-term stable operation and the continuous solid circulation between two reactors could be achieved successfully. The experimental results indicated that the solid circulation rate was increased with an increase of bed height, diameter of solid injection nozzle, and diameter of holes on the solid injection nozzle.