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Analysis of trace metal elements and chemical forms from waste combustion and its emissions control

垃圾燃烧中微量金属元素和化学形态分析及其排放控制

基本信息

批准号：
14380279
负责人：
NINOMIYA Yoshihiko
金额：
$ 9.47万
依托单位：
Chubu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380279/
关键词：
Combustion of waste material Trace metal Cascade impactor CCSEM Fly ash Particulate matter Chemical forms analysis PM2.5 下水汚泥化学形態別分析凝縮性粒子下水汚泥燃焼

项目摘要

Sewage sludge, pulverized coal and the mixture of them were subjected to combustion in a laboratory-scale drop tube furnace to investigate the emission of suspended particulate matter smaller than 10μm (PM_<10>) and to study the correlation of PM_<10> emission with inorganic species of them. Combustion conditions of 1200 to 1450℃ and 0 to 50% atmospheric oxygen concentration were used and all the carbon was consumed under given conditions. The exiting gas, containing the solid products, was initially quenched with N_2 and collected by a water-cooling probe. Subsequently, coarse ash particles were collected by a cyclone. The suspension of ultrafine particles was further diluted with air, and immediately directed to a Low-Pressure-Impactor (LPI) for size-segregated collection. The LPI used here is composed of 13 stages having aerodynamic cut-off diameters ranging from 0.03 to 12.1 μm. Each stage is composed of a quartz or Teflon filter above a substrate and a substrate holder. All the fi … More lters were analyzed by XRF, XRD, Computer controlled scanning electron microscopy (CCSEM), ICP-AES, XPS and TEM to quantify the elemental composition and chemical forms. The properties of PM_<10> were studied including its concentration, particle size distribution, elemental composition and chemical forms.The results indicated that, both the ash content in the fuels and the oxygen content in gas atmosphere affected PM_<10> concentration significantly. With their increasing, PM_<10> concentration was enhanced exponentially. PM_<10> was formed having a lognormal non-gaussian size distribution. Vaporization of the inherent metals plays the paramount role on PM_<10> formation. The inherent alkali, heavy metals and a portion of Si, P, and Fe initially vaporize the resultant metallic vapors undergo oxidization to form their nuclei around 0.03μm, which subsequently undergo coagulation according to the polydisperse coagulation model. Simultaneously, the heterogeneous coagulation between the different species allowed the formation of new chemical species such as alkali/zinc phosphate and sulfates. In addition, a small amount of particles larger than 1.0μm were also found, which was dominated by the refractory metals resulted from the direct transferring of inherent minerals in the fuels. PM_<1+> was formed by the direct transformation of refractory elements in the fuels. Quartz and aluminosilicates within this portion were formed by transformation without phase change. Meanwhile, calcium/iron aluminosilicate in PM_<1+> was formed by the reaction of calcium or iron with aluminosilicate, which led to a sticky surface of the latter compound. Alkali aluminosilicate was formed as melt droplets in combustion and it condensed into large particulates in PM_<1+>. PM_1 is rich in both sulfates and phosphates of vaporized elements. The degree of vaporization of elements is determined by their content (organically bound and included minerals smaller than 10.0 μm) in the raw fuels. The elemental type also affects their vaporization greatly, which decreases in the order of Na > K > Fe > Mg > Ca > Si > Al. This is fairly consistent with the predictions of thermodynamic equilibrium calculations. The vaporized metals reacted with gaseous S0_2, P_2O_5 and SiO to form their compounds. Less

在实验室沉降炉中对污泥、煤粉及其混合物进行了燃烧试验，研究了污泥、煤粉及其混合物中小于10μm悬浮颗粒物（PM_2）的排放特性<10>及其<10>与无机形态的相关性。燃烧条件为1200 ~ 1450℃，大气氧浓度为0 ~ 50%，在给定条件下，碳被消耗殆尽。含有固体产物的排出气体先用N_2淬灭，然后用水冷探针收集。随后，通过旋风分离器收集粗灰颗粒。用空气进一步稀释超细颗粒的悬浮液，并立即将其引导至低压冲击器（LPI）以进行尺寸分离收集。这里使用的LPI由13级组成，气动截止直径范围为0.03至12.1 μm。每个平台由位于衬底上方的石英或特氟隆过滤器和衬底保持器组成。所有的Fi ...更多信息通过XRF、XRD、计算机控制的扫描电子显微镜（CCSEM）、ICP-AES、XPS和TEM分析过滤物以量化元素组成和化学形式。研究<10>了燃料中PM_2的浓度、粒径分布、元素组成和化学形态，结果表明，燃料中灰分含量和气氛中氧含量对PM_2浓度<10>有显著影响。随着它们的增加，<10>PM_2浓度呈指数增长。PM_2<10>形成具有对数正态非高斯尺寸分布。固有金属的蒸发对PM_2的形成起着至关重要的作用<10>。固有的碱金属、重金属和部分Si、P和Fe首先蒸发，所产生的金属蒸气经历氧化以在0.03μm附近形成其核，随后根据多分散凝聚模型进行凝聚。同时，不同物种之间的非均相凝聚允许形成新的化学物种，如碱金属/磷酸锌和硫酸盐。此外，还发现了少量大于1.0μm的颗粒，主要是燃料中固有矿物直接迁移形成的难熔金属。PM <1+>是由燃料中难熔元素直接转化形成的。这部分中的石英和铝硅酸盐是通过转变而形成的，而没有相变。同时，PM <1+>中的铝硅酸盐是由钙或铁与铝硅酸盐反应生成的，后者的表面具有粘性。碱金属铝硅酸盐在燃烧过程中以熔滴形式形成，在PM <1+>中凝结成大颗粒. PM_1中富含蒸发元素的硫酸盐和磷酸盐。元素的蒸发程度取决于其在原燃料中的含量（有机结合和小于10.0 μm的矿物）。元素类型对它们的蒸发也有很大影响，其蒸发顺序为Na > K > Fe > Mg > Ca > Si > Al，这与热力学平衡计算的预测是一致的。气化的金属与气态SO_2、P_2O_5和SiO反应生成化合物。少