Modeling sulfur dioxide capture in a pulverized coal combustor

The formation and capture of sulfur dioxide in a pulverized coal combustor is investigated. A two-dimensional, steady, axisymmetric code, PCGC-2 (Pulverized Coal Gasification and Combustion - 2 Dimensional) originally developed at Brigham Young University has been used to simulate combustion of the pulverized coal. This paper represents part of a project to investigate simultaneously enhancing sulfur capture and particulate agglomeration in combustor effluents. Results from the code have been compared to experimental data obtained from MTCI's (Manufacturing Technology and Conversion International) test pulse combustor which generates sound pressure levels of -180 dB. The overall goal behind the pulse combustor program at MTCI is to develop combustors for stationary gas turbines which use relatively inexpensive coal-based fuels. This study attempts to model the capture of sulfur dioxide when injected into a pulse combustor firing micronized coal. While this work does not presume to model the complex gas flow-field generated by the pulsating flow, the effects of the acoustic field are expressed by increased heat and mass transfer to the particles (coal/sorbent) in question. A comprehensive calcination-sintering-sulfation model for single particles was used to model the capture of sulfur dioxide by limestone sorbent. Processes controlling sulfation are external heat and mass transfer, pore diffusion, diffusion through the product layer of CaSO₄, sintering and calcination. The model was incorporated into the PCGC-2 program. Comparisons of exit concentrations of SO₂ showed a fairly good agreement (within-10%) with the experimental results from MTCI.