The effect of sintering on sulphur capture by limestone and dolomite. Agnew, J.; Hampartsoumian, E.; Jones, J.M.; Nimmo, W. Journal of the Energy Institute, June 2005, Vol 78 No 2, pp 81-89.

In-bed sulphur capture is an attractive method for reducing SO2 emissions from coal-fired IGCC power plants. Sulphur (H2S) capture efficiency is dependent upon four competing rates: (i) calcination of sorbent to the oxide with concomitant surface area growth, (ii) sintering of the oxide with an associated decrease in surface area, (iii) sulphiding of the sorbent/calcined sorbent and (iv) sintering of the sulphide. The factors which influence these competing rates have been investigated. Two limestones and a dolomite were calcined in a drop-tube reactor under a combustion atmosphere to obtain samples of varying degrees of calcination and sintering. The results were modelled to yield apparent calcination and sintering rate constants. The partially calcined materials were sulphided in a fixed-bed reactor under a simulated gasification atmosphere. Conversions to the sulphide of up to 30% were observed, alongside rapid losses in surface area. The sintered sulphide forms an impermeable structure over the particle surface, which impedes diffusion of the reacting gas. Efficiency of sulphur capture was optimal at 873 and 973 K. At these lower temperatures, the slower sintering of the sulphide allows the preservation of pore structure.