新型乏气热风复合送粉系统低 NOx燃烧特性的数值模拟研究

摘要

Exhaust-air and hot wind composite powder feeding technology could feed pulverizing exhaust-air in primary wind system for powder feeding and avoid bad influence on pulverized coal burn-out and NOx emission by tertiary wind with low pulverized coal concentration.Therefore,a kind of low NOx and low nitrogen combustion technology for new multi-coal a-daptability by using pulverizing exhaust-air transfer and wind hot for composite powder feeding was proposed.By means of numerical simulation method,influence on NOx emission mass concentration and coal burn-out process by exhaust-air trans-fer of the new low NOx combustion system was studied.Results indicate that exhaust-air transfer amount of the new system may increase which might result in pulverized coal burn-out rate decrease but could obviously reduce NOx emission mass con-centration.In practical boiler testing,boiler efficiency reached up to 94% and NOx emission mass concentration was 207.Excellence of each index proved that this system was of remarkable low NOx combustion effectiveness and strong practicability.%乏气热风复合送粉技术可以将制粉乏气送入一次风系统进行送粉,避免低煤粉浓度的三次风对煤粉燃尽和氮氧化物(NOx )排放的不利影响,基于此,提出一种利用制粉乏气转移与热风进行复合送粉的新型多煤种适应性的低 NOx 低氮燃烧技术。通过数值模拟方法研究了新型低 NOx 燃烧系统乏气转移对 NOx 排放质量浓度和煤粉燃尽过程的影响,结果表明,新型系统的乏气转移量增加,虽然会使得煤粉燃尽率略有下降,但是可以显著降低 NOx 排放质量浓度。在实炉测试时乏气转移系统后锅炉效率能达到94%,NOx 排放质量浓度为207 mg/m3(φ(O2)=6%),各项指标优良,表明该系统具有显著的低 NOx 燃烧效果,实用性强。