The Study Of Attrition Performance Of Calcium-based Sorbent Modified By Fly-ash In A Fluidized Bed

CO2 capture has been attracted great attention since people have known more about global warming and climate change due to CO2 emission. As the major stationary source for CO2 emission, power plants are the main candidate for CO2 capture. At present calcium-based sorbent calcination/carbonation for CO2 capture was considered as one of the most attractively technologies for power plants.In order to solve the problem of decline of carbonation conversion with cycle number increased, methods had been attempted to modify the calcium-based sorbent by fly-ash and the modified sorbents achieved enhanced CO2 capture performance. Nevertheless, attrition of the sorbents during fluidized is an important issue for the technology. In order to realize the improvement of CO2 capture and decrease of cost, it is necessary to study the attrition performance of sorbent modified by fly-ash.Effects of calcination time, particle size, calcination temperature, gas velocity and calcination atmosphere on attrition of the sorbents were studied. A comparison was made between modified sorbent and limestone in attrition properties. The results show that the attrition rate of sorbent particle decreases with time. The greater the particle size and gas velocity is, the more serious the particle attrition is presented. In the initial 10 min, the attrition is more severe at 950℃ than that at 850℃ during calcination. With calcination time prolonged, the attrition of sorbent is more severe at 850℃ than that at 950℃ inversely. Attrition of sorbent particle is moderate in CO2 atmosphere compared with that in air atmosphere. High CO2 concentration hinders the calcination of sorbent and leads to moderate the particle attrition. The sorbent particle modified with fly ash presents stronger attrition resistance than that of limestone.The attrition characteristic of calcium-based sorbents particle was carried out during the calcination/carbonation looping cycles. The influences of CO2, H2O and SO2 concentration in calcination/carbonation atmosphere on attrition behavior were also investigated. The difference in microstructure of the sorbents were studied. The results show that the sharp of sorbent particles became rounding off, with the progress of fluidization. The presence of H2O and SO2 can decrease the production of grain powder caused by attrition. It is because H2O may aggravate the sintering of sorbent particle, and sulphation may make the surface of sorbent particle densified. Attrition of sorbent particle is moderated as a result.