钙基CO_2吸收剂的种类和粒径对循环煅烧/碳酸化的影响

EFFECTS OF Ca-BASED CO_2 SORBENT TYPE AND PARTICLE SIZE ON MULTIPLE CARBONATION/CALCINATION CYCLE

在流化床反应器内研究了吸收剂种类(石灰石、白云石)和颗粒粒径(90～200μm和200～450μm)对钙基吸收剂碳酸化特性、煅烧特性以及循环稳定性的影响,并对新型CaO/Ca_(12)Al_(14)O_(33)吸收剂的循环稳定性进行研究.结果表明,钙基吸收剂在流化床内均能有效吸收CO_2.在碳酸化阶段,吸收剂种类对吸收剂的吸收特性影响较大,而颗粒粒径对其影响较小;在煅烧阶段,CaCO_3分解速率随颗粒粒径的减小而增大.随着循环反应次数的增加,钙基吸收剂反应活性下降,相对于白云石和石灰石,CaO/Ca_(12)Al_(14)O_(33)具有更高的循环稳定性,并在七次循环后活性不再发生变化.对于石灰石吸收剂,循环稳定性随循环次数的变化受粒径影响较小.白云石吸收剂由于在循环中容易破碎,因此粒径对其循环稳定性有一定的影响.

Effects of sorbent type （limestone, dolomite） and particle size （90-200μm and 200-450μm） on carbonation/calcination characteristics and cyclic stability were investigated by a fluidized bed reactor, so was the cyclic stability of CaO/Ca12Al14O33. Experimental results show that CO2 in the flue gases can be absorbed effectively by all sorbents in the fluidized bed. In the process of carbonations, the effect of sorbent type on the CO2 sorption characteristics is large, but particle size is not. In the process of calcinations, the decomposition rate of CaCO3 increases with the decrease of the particle size. With increasing of the carbonation/calcination cycles, cyclic sorption reactivities of CaO decline. Comparing with limestone and dolomite, CaO/Ca12Al14O33 has more stable cyclic reactivity which keeps constant after 7 cycles. For limestone, particle size has little effect on the cyclic reactivity of the sorbent. Because of particle fragmentation, particle size of dolomite has some effects on the cyclic stability during the carbonation/calcination cycles.