生活垃圾混烧秸秆类生物质颗粒CO和NO的排放特性

选取典型秸秆类生物质颗粒掺混垃圾作为研究对象,利用自制燃烧试验平台,研究掺混比、温度、粒径及生物质种类等因素对垃圾掺混生物质颗粒燃烧过程中CO与NO释放规律的影响。试验结果表明:CO排放量随着混合燃料中棉花秆颗粒含量增加而减小;混合燃料中垃圾掺混量高于棉花秆颗粒时,焦炭氮燃烧峰值随棉花秆含量增加而增大,掺混量低于棉花秆颗粒时,焦炭氮燃烧峰值逐渐减小,掺混比为5:5时NO生成量最低。燃烧温度为850℃时CO生成量最低;NO峰值时间随温度升高向前偏移,排放量呈先增大后减小趋势,较高的反应温度有利于降低燃烧过程中NO生成量。随着燃料粒径减小,CO峰值浓度降低;存在粒径临界值(60~80目),当粒径小于临界值时,NO生成量随粒径减小而减小,大于临界值时,NO生成量随粒径增大而减小。垃圾混烧生物质颗粒后CO生成量显著降低;掺混同质量分数生物质颗粒试样中,生物质颗粒氮含量越高,混合燃料燃烧NO生成量越大。该研究可为实际生产中城市生活垃圾混烧生物质颗粒技术及污染物排放控制提供参考依据。

Emission characteristics of CO and NO during co-combustion with municipal solid waste and straw biomass pellets

The straw biomass pellets are co-combusted with municipal solid waste (MSW), which can solve the problems of insufficient supply and low calorific value of MSW, and also avoid mouldiness and spontaneous combustion due to long-term transport and storage of biomass before briquetting. However, researches on the combustion and emission characteristics of MSW mixed with straw biomass pellets are rarely reported. The experiment at constant temperature was designed to investigate the CO and NOxemission characteristics of MSW and straw biomass pellets co-combustion under the different conditions: blending ratio (10:0, 9:1, 7:3, 5:5, 3:7, 1:9 and 0:10), temperature (650, 750, 850, 950, 1050 and 1150℃), particle size (30-40, 40-60, 60-80, 80-230 and greater than 230 meshes) and biomass species (cotton straw, corn stalk, corncob and rice straw). The results from the experiments indicated that the CO concentration was reduced with the increase of cotton straw pellets’ ratio in the blended fuel and the burnout time moved forward. When the amount of MSW was higher than that of cotton straw pellets, the combustion peak value of NO was elevated by increasing the content of cotton straw pellets, and vice verse. The released amount of NO was reduced to the minimum as the blending ratio of MSW to cotton straw pellets was 5:5. The emission concentration of CO reached the minimum under the combustion temperature of 850℃. The peak time of NO moved forward with the increase of temperature, and the yields firstly increased, and then decreased. The higher reaction temperature caused the reduction of NO generation in the process of combustion. The peak concentrations of CO were reduced by decreasing the size of fuel particles. The particles had the threshold size of less than 60-80 meshes, and under this threshold size, the NO emission concentrations declined with the decreasing of particle size; while the particle size exceeded the threshold, the NO emission concentrations declined with the increasing of particle size. Compared to the result from the combustion of MSW, the CO peak concentration of MSW co-fired with biomass pellets dropped significantly. For the MSW mixed with the equal mass ratio of different biomass species, the higher nitrogen content of biomass pellets can result in the higher yields of NO during the co-combustion. These results can be as the reference for the actual production of MSW co-combustion with biomass particles and the pollutant emission control technology.