Experimental Study On The Corresponding CO₂ Sorption Performance Of K₂CO₃/Al₂O₃ In A Coupled Bubbling Bed-Transport Bed Carbonator

Carbon dioxide(CO2),thought to be the main greenhouse gas that leads to the global warming,has been attracted significant attention of the world over the past decade.CO2 capture from power plant is thought to be one of the effective methods to reduce CO2 emission in China since power plant is the largest source of carbon emission.Using a dry alkali-based sorbent for capturing CO2 from flue gas is considered to be one of the innovative and feasible capture technologies.However,besides the sorbent,lacking of a stable,cost-effective reactor is another issue that limits its application.To solve this problem,this paper has done some work on the following aspects.Firstly,A new type of continuous CO2 capture system was designed and constructed.The design of this system is based a coupled fluidized bed carbonator(coupling the bubbling bed and transport bed to integrate the advantages of these two types of reactors)and a bubbling fluidized bed regenerator.This system can realize the flexible and independent adjustment of the material circulation flow and the gas-solid contact time to improve CO2 capture efficiency and absorbent utilization.Secondly,the material external circulation characteristics of the bubbling bed-transport bed coupled continuous CO2 capture system was investigated.The parametric test results show that the static bed height of bubbling section and the central air gas flow have a great influence on the amount of material transportation amount.The material transportation amount increases with increasing the static bed height of bubbling section and the center wind gas flow.The fluidization number has little influence on the material transportation amount.The effect of return air and resting bed height on the material returning amount is small.On the contrary,when fixing the return wind gas flow,the material returning amount increases linearly with the increasing of loose wind.Thirdly,the corresponding CO2 capture performances were evaluated by investigating the effect of different operation parameters based on KAl30 sorbent.The circulation characteristics ofthe solid K2CO3/Al2O3 sorbent in the system were studied and the corresponding CO2 capture performance were evaluated by investigating the effect of different operation parameters such as the solid circulation rate,bed height,carbonation temperature,regeneration temperature and water vapor concentration during continuous operation of the system.The result shows that the CO2 capture efficiency of the sorbent is sensitive and increases with the increase of the solid circulation rate,bed height,water vapor concentration and regeneration temperature.Meanwhile,the CO2 capture efficiency can be maintained at a relative high level when changing the carbonation temperature at the range of 60? to 100?.Finally,A 24-hour continuous operation test was conducted with the optimizing operating condition.The result shows that the CO2 capture efficiency of this system is well maintained at about 80%,also the CO2 capture efficiency keeps stable during the long time operation.After 24-hours continuous operation,the average particle size of the absorbent decreased from 0.3mm to 0.275mm.The variation of the particle size distribution with time shows that the abrasion of the absorbent occurred mainly at the beginning of the reaction,and then the average particle size remained basically unchanged.It is proved that the absorbent has a good abrasion resistance capability.