The characteristics of simultaneous calcination and sulfation of limestone in the atmosphere simulating circulating fluidized bed oxy-fuel combustion were studied using an experimental system that could measure sample mass changes at a preset temperature. The pore structure and conductivity of samples were measured to study the diffusion mechanism in the product layer. Compared with CaO that was calcined without SO2

the porosity of CaO was easier to be blocked up and the process had a shorter duration before transfering into the diffusion control stage when limestone calcination and sulfation occured simultaneously. A higher sulfation rate and higher conversion were observed because of higher diffusibility in the product layer than that of CaO calcined without SO2. Sintering of CaO would decrease its sulfation capability

especially when temperature was above 950℃. Particle size was an important factor that determined sulfation of sorbents

and higher sorbent utilization would be obtained for smaller particles. Also

higher SO2 concentration would improve sulfation of sorbents. A grain-micrograin model was set up

and the effects of some factors

such as temperature

sorbent particle size and SO2 concentration were simulated. The calculation results fitted well with the testing.