Behavior of lead compounds during municipal solid waste incineration
Behavior of lead compounds during municipal solid waste incineration
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DOI：
10.1016/j.proci.2008.07.026
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
H. Yao;I. Naruse
中科院分区：
文献类型：
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作者：
H. Yao;I. Naruse
为了降低焚烧炉底灰中重金属的浓度，采用电热管炉对铅化合物在模拟城市生活垃圾焚烧过程中的行为进行了研究。实验中选择特殊鱼食作为模拟废弃物，将其单独燃烧，并与PbO、pbcl2、PbSO4等纯铅化合物混合。对于模拟废物与PbO混合，还进行了在燃烧空气中添加HCl气体的试验。炉温为873 ~ 1273K，燃烧空气化学计量量为0.5 ~ 1.2。采用水冷取样探头在炉膛出口等速取样灰颗粒，探头尖端注入氮气对燃烧气体和灰颗粒进行淬火。然后，这些颗粒被一个有13个阶段的低压撞击器分离。结果表明：铅在小于1μm细颗粒中的富集趋势与铅化合物的熔融温度有关；在三种先导化合物中，pbcl2最容易富集到细颗粒中，pbso4在低温条件下最难富集到细颗粒中。然而，当HCl气体与燃烧空气混合时，即使在低温下，细颗粒中也会富集更多的Pb。低燃烧空气化学计量量促进了含有高浓度铅的大量细颗粒的形成。铅在粗颗粒中的富集机理受铅化合物蒸气与灰颗粒表面反应的控制。二级焚烧炉采用温度较高、化学计量空气比较低的一级气化区，有利于将垃圾焚烧过程中底灰富集的铅转化为飞灰。
In order to depress the concentration of heavy metals in the bottom ash in the incinerator, the behavior of lead compounds during simulated municipal solid waste (MSW) incineration was investigated, using an electrically heated drop tube furnace. In the experiments, special type of fish food was chosen as the simulated waste, which was burned alone and also blended with pure lead compounds, such as PbO, PbCl2and PbSO4. For the simulated waste blending with PbO, test with addition of HCl gas into the combustion air was also conducted. The furnace temperature and combustion air stoichiometry were varied from 873 to 1273K and 0.5 to 1.2, respectively. Ash particles were isokinetically sampled at the furnace exit by a water-cooled sampling probe, at the tip of which N2gas was injected to quench the combustion gas and particles. Those particles were then separated by a low pressure impactor with 13 stages. The results show that the tendency of the lead enrichment in the fine particles less than 1μm depends on the melting temperatures of the lead compounds. Of the three lead compounds, PbCl2is enriched the most into the fine particles, and PbSO4is the most difficult at the low-temperatures examined. However, when HCl gas was mixed with the combustion air, more Pb is enriched in fine particles even at low temperatures. The low combustion air stoichiometry enhances formation of a large amount of fine particles containing high concentrations of lead. The mechanism of Pb enrichment in the coarse particles is controlled by the surface reaction of vapor of Pb compounds with the ash particles. Two-stage incinerator including a first-stage gasification zone with higher temperature and lower stoichiometric air ratio, is preferable to shift the Pb enrichment from bottom ash into fly ash during waste incineration.