Sulfation behavior of limestone under high CO2 concentration in O2/CO2 coal combustion

Coal combustion with O2/CO2 is promising because of its easy CO2 recovery, extremely low NOx emission and high sulfation efficiency. The mechanism of direct sulfation of limestone under high CO2 concentration, different from that of CaO–SO2 sulfation, is one of the factors to account for its high sulfation efficiency. However, many unknowns about the mechanism of direct sulfation exist. The mechanisms and kinetics of direct sulfation were examined. Both experiment and modeling suggested that sintering is much mitigated during direct sulfation of limestone. The rate of direct sulfation does not decrease so much with sulfation degree as CaO–SO2 sulfation. Direct sulfation is favorable for high sulfation degree. Furthermore, the diffusivity in the product layer demonstrates high temperature dependence and hardly changes with sulfation degree. This result is associated with the fact that the calcium sulfate layer produced is porous owing to CO2 formation.

[1]  A. B. Fuertes,et al.  Sulphur retention by limestone particles under PFBC conditions , 1993 .

[2]  D. D. Perlmutter,et al.  The effect of pore structure on fluid‐solid reactions: Application to the SO2‐lime reaction , 1981 .

[3]  K. Dam-Johansen,et al.  High-temperature reaction between sulfur dioxide and limestone—VI. The influence of high pressure , 1993 .

[4]  Ken Okazaki,et al.  NOx reduction mechanism in coal combustion with recycled CO2 , 1997 .

[5]  P. Davini.  Thermogravimetric study of the characteristics and reactivity of CaO formed in the presence of small amounts of SO2 , 1995 .

[6]  Adel F. Sarofim,et al.  Analysis and modeling of the direct sulfation of CaCO3 , 1988 .

[7]  G. D. Piero,et al.  Behaviour of calcium-based sorbents towards SO2 capture in a high pressure thermobalance , 1992 .

[8]  Adel F. Sarofim,et al.  DIRECT SULFATION OF CALCIUM CARBONATE , 1988 .

[9]  K. Jensen,et al.  Estimation of effective transport coefficients in porous solids based on percolation concepts , 1985 .

[10]  Tiİmur Doǧu.  The Importance of Pore Structure and Diffusion in the Kinetics of Gas-Solid Non-catalytic Reactions: Reaction of Calcined Limestone with SO2 , 1981 .

[11]  M. Hupa,et al.  Comparison of SO2 capture capacities of limestones and dolomites under pressure , 1995 .

[12]  Antonio B. Fuertes,et al.  Study of the direct sulfation of limestone particles at high CO2 partial pressures , 1994 .

[13]  A. B. Fuertes,et al.  Analysis of the direct sulfation of calcium carbonate , 1994 .

[14]  James W. Evans,et al.  Gas-solid reactions , 1976 .