工业燃煤链条炉细粒子排放特征研究

Emission Characteristics of Fine Particles from Grate Firing Boilers

链条燃煤锅炉是当前我国工业锅炉的最主要应用炉型,其容量占到了工业锅炉总容量的85%,是重要的大气污染物排放源之一.本研究在3个地区选取了5种典型容量的链条炉,应用自行设计的二级稀释系统现场测试其细粒子（PM2.5）和各种气态污染物的排放特征.结果表明,链条炉烟气中的PM2.5质量粒径呈单峰或双峰分布,第1个峰值在0.14μm处,第2个峰值在1μm后;湿法除尘和旋风除尘对PM1.0的细粒子仍具有有效的去除效率;在相同或相似除尘控制技术的条件下,PM2.5的排放水平随锅炉容量的增大而减小.在PM2.5中,SO4^2-是最丰富的离子,质量分数在20%-54%范围内;C是最丰富的元素,质量分数在7.5%-31.8%之间,其次是S,质量分数为8.4%-18.7%.采用碳平衡法计算得出PM2.5、NOx和SO2的排放因子分别为0.046-0.486 g.kg^-1、1.63-2.47 g.kg^-1、1.35-9.95 g.kg^-1,这为建立我国的工业锅炉排放清单及大气污染来源分析提供了必要的基础数据.

Grate firing boilers are the main type of Chinese industrial boilers, which accounts for 85 % of the industrial boilers and is one of the most important emission sources of primary air pollutants in China. In this study, five boilers in three cities were selected and tested to measure the emission characteristics of PM25, and gaseous pollutants were applied by a compact dilution sampling system, which was developed for this field study. Results showed that particles mass size distributions for the five industrial boilers presented single peak or double peak, former peaks near 0.14 μm and the later peaks after 1.0 μm; the cyclone dust remover and wet scrubber dust remover had effective removal efficiencies not only to PM2.5, but also to PM1.0 ; and under the condition of same control techniques, grate firing boiler with high capacity has less PM2.5 emission than the boiler with low capacity. In the PM2.5 collected from flue gases, SO4^2- was the most abundant ion, accounted for 20%-40% of the PM2.5 ; and C was the most abundant element （7.5%-31.8%）, followed by S （8.4%-18.7%）. Carbon balance method was applied to calculate the emission factors of these pollutants. The emission factors of PM2.5, NOx and SO2 were in the range of 0.046-0.486 g·kg^-1, 1.63-2.47 g·kg^-1, 1.35-9.95 g·kg^-1 respectively. The results are useful for the emission inventory development of industrial boilers and the source analysis of PM2.5 in atmospheric environment.