| 摘要 |
A method for effecting combustion of carbonaceous fuel is operative to sustain the combustion at a predetermined rate or rates of total fuel demand, the fuel being distributed between two combustion stages to make up the required total feed rate. Thus one portion, usually about 20-70 percent, of the total fuel is fed to a thermal combustion stage. Sufficient air is supplied simultaneously to the thermal combustion stage, preferably about 125 to 185 percent of the stoichiometric amount of air, to effect substantially complete combustion of that portion of the fuel and produce a heated effluent. An additional amount of relatively cool air is mixed with this effluent, and the resulting cooled mixture continues through the mixing zone, the additional air being sufficient to inhibit preburning of the remaining portion of the fuel which is added downstream in the mixing zone. This cooled mixture in the mixing zone, upon and following the introduction of the additional fuel, is at temperatures within the range of about 500 DEG -1200 DEG F. The enriched fuel-air admixture then is combusted in the presence of a catalyst, the admixture providing combustion conditions in the catalyst stage giving a high rate of heat release without substantial formation of pollutants. |
