民用燃料烟气中气态污染物及水溶性无机离子的排放

选取北京市地区典型生物质燃料（玉米芯、玉米秆、黄豆秆、草梗、松木、栗树枝、桃树枝）以及民用煤（烟煤、蜂窝煤）在实验室内进行了模拟燃烧实验，采用Thermo Fisher 42i型化学发光NO-NO₂-NOx分析仪、43i型脉冲荧光SO₂分析仪、48i型CO分析仪对烟气中的NO_x、SO₂、CO进行全程在线监测；对燃烧产生的颗粒物样品进行采集，采用ICS 90A、ICS2000离子色谱仪对不同粒径段颗粒物中的水溶性无机离子进行测定.研究表明：3类民用燃料排放因子均值由大到小的顺序，SO₂为民用煤 > 薪柴 > 秸秆；CO为秸秆 > 民用煤 > 薪柴；NO_x为薪柴 > 民用煤 > 秸秆.薪柴燃烧产生的PM_2.5中SO₄^2-含量最高，占总水溶性无机离子的22%~30%；秸秆类燃烧产生PM_2.5中的水溶性无机离子K⁺占绝对优势，占总水溶性无机离子的36%~49%，其次为Cl^-或SO₄^2-，两者之和占总水溶性无机离子的35%~44%.3类民用燃料中秸秆类燃烧排放的颗粒物中水溶性无机离子的排放因子最高，其次为薪柴类燃料，民用煤最低.本实验对不同粒径段颗粒物中9种水溶性无机离子进行了分析（Na⁺、K⁺、Mg²⁺、Ca²⁺、NH₄⁺、F^-、Cl^-、NO₃^-、SO₄^2-），薪柴类燃料燃烧排放的颗粒物中，Na⁺、K⁺、NH₄⁺、F^-的排放因子在0~2.5μm粒径段内最大，Mg²⁺和Ca²⁺的排放因子在2.5~10μm粒径段内最大.秸秆类燃料除Ca²⁺、Mg²⁺外，其余离子的排放因子均在0~2.5μm粒径段内达到最大.对于烟煤而言，除了K⁺、Mg²⁺和Ca²⁺外，其余离子的排放因子均在0~2.5μm粒径段内达到最大；蜂窝煤中Na⁺、K⁺、Cl^-、NO₃^-、SO₄^2-的排放因子均在0~2.5μm粒径段内达到最大.

Emission of gaseous pollutants and water-soluble inorganic ions from civil fuel flue gas

The typical biomass fuels (made of corn cob, corn stalks, soybean stalks, straw stalks, pine, chestnut branches, peach branches) and civil coal (bituminous coal, honeycomb coal) were selected in Beijing to carry out simulated combustion experiments in the laboratory. The whole-process online monitoring of NO_x, SO₂ and CO in flue gas was carried out using Thermo Fisher 42i chemiluminescence NO-NO₂-NO_x analyzer, 43i pulsed fluorescence SO₂ analyzer and 48i CO analyzer. The particle samples were collected and the water-soluble inorganic ions in the particles of different particle sizes were measured by ICS 90A and ICS2000ion chromatograph. The results showed that the average emission factors of SO₂ from three kinds of civil fuels were civil coal > fuelwood > straw; CO emission factors were straw > civil coal > fuelwood; and NO_x emission factors were fuelwood > Civil coal > straw.The content of SO₄^2- in PM_2.5 of firewood combustion is the highest, accounting for 22%~30% of the total water-soluble ions. K⁺ takes an absolute advantage in the composition of water-soluble ions in PM_2.5 of straw, accounting for 36%~49% of the total water-soluble ions. Among the three types of civil fuels, straw combustion has the highest emission factor of water-soluble inorganic ions, followed by fuelwood fuel and civil coal. Nine kinds of water-soluble inorganic ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, NH₄⁺, F^-, Cl^-, NO₃^-, SO₄^2-) were analyzed in this experiment. The emission factors of Na⁺, K⁺, NH₄⁺, F^-from firewood combustion are the largest in the the range of 0~2.5μm, while those of Mg²⁺ and Ca²⁺ are the largest in the in the range of 2.5~10μm. Except Ca²⁺, Mg ²⁺, the emission factors of other ions from straw fuels reached the maximum in the range of 0~2.5μm particle size. For bituminous coal, except K⁺, Mg²⁺ and Ca²⁺, the emission factors of other ions reach the maximum in the particle size range of 0~2.5μm. The emission factors of Na⁺, K⁺, Cl^-, NO₃^-, SO₄^2-in honeycomb coal reach the maximum in the range of 0~2.5μm particle size.