化学链燃烧中载氧体结构设计对抗磨性的影响研究

Study on Effect of Structure Design of Oxygen Carriers in Chemical Looping Combustion on Abrasion Resistance

在化学链反应过程中,载氧体作为氧和热量的载体起着至关重要的作用,载氧体设计一直是化学链技术研究的重点和难点。化学链燃烧通常发生在流化床反应器中,由于化学反应带来的化学应力对载氧体磨损贡献率最大,导致载氧体寿命大大缩短,有效成分流失。从载氧体结构设计角度出发,定性评价了不同复合载氧体的抗磨损机理:核壳结构抑制了活性组分的相分离现象,避免了由于活性组分表面磨损带来的载氧体失活;添加Al_(2)O_(3)纤维和“铆钉”抑制了裂纹扩展,减缓了材料的磨损;添加燃料灰改善了复合载氧体的骨架强度,提高了载氧体抗磨性和抗结渣团聚性;利用复合载氧体的协同增效提高了反应活性,减缓了烧结团聚现象。从磨损动力学和使用寿命角度出发,定量比较了不同载氧体的磨损情况:通过对数拟合Gwyn磨损动力学方程,求出不同载氧体拟合参数K和n,可以反映磨损机制和磨损变化规律。

During chemical looping combustion,oxygen carrier plays a crucial role as the carriers of oxygen and heat.Design of oxygen carrier has always been the emphasis and difficulty in chemical looping technology research.Chemical looping combustion usually occurs in a fluidized bed reactor.Since the chemical stress caused by chemical reactions has the greatest contribution rate to the abrasion of oxygen carrier,the life of oxygen carrier is significantly shortened and the effective components run away.From the perspective of oxygen carrier structure design,the anti-abrasion mechanism of different composite oxygen carriers was qualitatively evaluated.The core-shell structure inhibits the phase separation of the active components and avoids the deactivation of oxygen carrier caused by surface abrasion of the active components.The addition of Al_(2)O_(3) fiber and"rivet"inhibits crack growth and slows down the abrasion of the material.The addition of fuel ash improves the skeleton strength of the composite oxygen carriers,and the resistance to abrasion and slagging aggregation of oxygen carriers.The synergistic effect of the composite oxygen carrier increases the reactivity and slows down the sintering agglomeration phenomenon.From the perspective of abrasion dynamics and service life,the abrasion conditions of different oxygen carriers were quantitatively compared.By logarithmically fitting of the Gwyn abrasion dynamics equation,fitting parameters K and n of different oxygen carriers were calculated,which reflects the abrasion mechanism and abrasion patterns.