| Contents Notes |
The Clean Air Act Amendments of 1990 (CAAA) have led to accelerated research into novel sulfur dioxide (SOb2s) and nitrogen oxide (NOx) control technologies for coal-fired industrial boilers. One of these technologies combines sorbent injection and selective non-catalytic reduction for simultaneous SOb2s/NOx removal. The work presented herein concentrated on characterizing three process operational parameters of this technology: injection temperature, sorbent type, and reductant/pollutant stoichiometric ratio. A slurry composed of a urea-based solution (NOx OUT A or NOx OUT A+) and various calcium-(Ca- ) based sorbents was injected at a range of temperatures and reactant/pollutant stoichiometries in a natural-gas-fired, pilot-scale reactor with doped pollutants. Up to 80% reduction of SOb2s and NOx at reactant/pollutant stoichiometric ratios of 2 and 1.5, respectively, was achieved. SOb2s emission reductions from slurry injection were enhanced moderately when compared with dry sorbent injection methods, possibly caused by sorbent fracturing to smaller, more reactive particles. Emissions from ammonia (NHb3s) slip (unreacted nitrogen-based reducing agent) and nitrous oxide (Nb2sO) formation were reduced in comparison with other published results, while similar NOx reductions were obtained. increased carbon monoxide (CO) emissions, caused by the decomposition of urea, were moderate. Emissions of CO, NHb3s, and Nb2sO for the enhanced urea solution (NOx OUT A+) were substantially less than the levels observed during urea (NOx OUT A) injection. The injection of the urea-based solution enhanced SOb2s removal, probably because of the formation of (NHb4s)b2sCA(SOb4s)b2s Hb2sO. The results of this pilot-scale study have shown high reduction of both SOb2s and NOx. |
