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

将污水污泥、煤粉及其混合物在实验室规模的落管式炉中燃烧，研究小于10μm悬浮颗粒物（PM_<10>）的排放情况，并研究PM_<10>排放的相关性燃烧条件为1200～1450℃，大气氧浓度为0～50%，在给定条件下碳全部被消耗。含有固体产物的排出气体首先用N_2骤冷并通过水冷探针收集，随后通过旋风分离器收集粗灰颗粒。超细颗粒的悬浮液进一步用空气稀释，并立即引导至低浓度。 -用于按尺寸分离收集的压力冲击器 (LPI) 此处使用的 LPI 由 13 个阶段组成，其空气动力学截止直径范围为 0.03 至 0.03。每个阶段均由位于基板和基板支架上方的石英或聚四氟乙烯过滤器组成。所有过滤器均通过 XRF、XRD、计算机控制扫描电子显微镜 (CCSEM)、ICP-AES、XPS 和 TEM 进行分析。研究了PM_<10>的元素组成和化学形态，包括其浓度、粒径分布、元素组成和化学形态。结果表明，灰分含量。燃料中的氧气含量和气体气氛中的氧气含量显着影响PM_<10>浓度，随着它们的增加，PM_<10>浓度呈指数增加，形成具有对数正态非高斯分布的固有蒸发。金属对PM_<10>的形成起着至关重要的作用，固有的碱金属、重金属和一部分Si、P和Fe首先蒸发，所得金属蒸气经历氧化以在周围形成它们的核。 0.03μm，随后根据多分散混凝模型进行混凝，同时不同物质之间的异质混凝允许形成新的化学物质，例如碱金属/磷酸锌和硫酸盐。此外，还有少量大于1.0的颗粒。还发现了PM_<1+>，其主要是由于燃料中固有矿物质的直接转移而形成的难熔金属。该部分燃料中的难熔元素是通过相变直接转化形成的，而PM_<1+>中的钙/铁铝硅酸盐是由钙或铁与铝硅酸盐反应形成的。碱金属铝硅酸盐在燃烧中形成为熔体液滴，并且在PM_1+中凝结成大颗粒。 PM_1富含汽化元素的硫酸盐和磷酸盐，元素的汽化程度取决于其在原燃料中的含量（有机结合和包含的小于10.0μm的矿物质），元素类型也对其汽化程度有很大影响，从而降低了元素的汽化程度。顺序为Na>K>Fe>Mg>Ca>Si>Al，这与热力学平衡计算的预测相当一致。 S0_2、P_2O_5和SiO形成的化合物较少。