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Developing Suppression Techniques for Dioxin (DXN)s Released from Small-scale Incinerators for Industrial Wastes by Adding Titania Particles

开发添加二氧化钛颗粒抑制小型工业废物焚烧炉释放的二恶英 (DXN) 技术

基本信息

批准号：
13555218
负责人：
EMI Hitoshi
金额：
$ 8.38万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

The present work is aimed at developing a method for suppressing the formation of dioxin (DXN)s emitted from small-scale incinerators for industrial wastes, which are difficult of operate under well controlled combustion, by adding a chemical (sulfur-contained titania) into incinerators. In the first year, the lab-scale experiments on incomplete combustion of me waste samples prepared by adding hydrated lime (Ca(OH)_2) with a given content into PVC powders were performed. The experiments revealed that the DXNs concentration in the burnt samples with 33.2wt%-added Ca(OH)_2 decreased by about 1/10 compared to that without the addition. However, we concluded that this technique adding chemicals into an incinerator is insufficient for the future regulation of tolal emission even if titania, which might be more reactive than Ca(OH)_2 is applied. Thus, we focused on the secondary heat treatment for fly ash in which DXNs arc most concentrated. In the conventional method, DXNs in the fly ash a … More re dechlorinated under reductive atmospheres below 500 deg. C. by adding some chemical since fly ash is subject to solidification above 500 deg. C. In the second year, we investigated the mechanism on solidification of fly ash at the high temperature and attempted to establish the technique of high-temperature treatment for fly ash preventing it from the solidification. Sodium hydroxide (NaOH) and mullile were chosen as an additive that can trap chlorine in fly ash, assuming that it might contribute the solidification, and then me chosen chemical was mixed with fly ash at a given ratio, followed by heating in an electric furnace at 700 deg.C. It was found that no solidification of fly ash with the additives took place after the heat treatment. Moreover, the X-ray diffractometer analyses indicated that the fly ash prior to the heating did not contain calcium chloride (CaCl_2) but CaClOH, which was a product of reaction between Ca(OH)_2 and HC1, and that sodium chloride (NaCl) was detected in the heated sample with NaOH and wadalite in the treated one with mullitc. The differential thermal analyses revealed that for the sample without additives there was an exothermic peak in ihe cooling step (around 800 deg.C). while this peak was not detected in that with additives. Furthermore, the DXNs in the samples before and after the heal treatment were analyzed. The results showed that DXNs concentration in the treated samples with additives decreased by less than 1/!05 compared to the untreated one without additives. These findings confirmed that the application of these additives has the advantages not only to prevent fly ash from the solidification but also to enhance the decomposition of DXNs. Less

本工作的目的是开发一种方法来抑制二恶英（DXN）的形成，从小规模的工业废物焚烧炉，这是很难在良好的控制燃烧下运行，通过添加化学品（含硫的二氧化钛）到焚烧炉。在第一年中，我们在PVC粉料中加入一定量的熟石灰（Ca（OH）_2），制备了一种废弃物试样，进行了不完全燃烧的实验室试验。实验结果表明，添加33.2wt% Ca（OH）_2的试样中DXNs的浓度比未添加Ca（OH）_2的试样中DXNs的浓度降低约1/10。然而，我们的结论是，这种技术添加到焚烧炉的化学品是不够的，为未来的总排放量的调控，即使二氧化钛，这可能是更活泼的比Ca（OH）_2的应用。因此，我们专注于二次热处理粉煤灰中的DXN弧最集中。在传统的方法中，粉煤灰中的DXN ...更多信息 Re在低于500 ℃的还原性气氛下脱氯。C.由于粉煤灰在500 ℃以上固化，C.第二年，我们研究了粉煤灰在高温下固化的机理，并试图建立防止粉煤灰固化的高温处理技术。选择氢氧化钠（NaOH）和莫来石作为可以捕获飞灰中的氯的添加剂，假设其可能有助于固化，然后将所选化学品与飞灰以给定比例混合，随后在电炉中在700 ℃下加热。结果表明，添加剂的粉煤灰在热处理后没有发生固化。此外，X射线衍射分析表明，加热前的粉煤灰中不含氯化钙（CaCl_2），而含有Ca（OH）_2与HCl反应生成的CaClOH，用NaOH加热后的粉煤灰中含有氯化钠（NaCl），用莫来石处理后的粉煤灰中含有钙铝石。差热分析表明，对于不含添加剂的样品，在冷却步骤中存在放热峰（约800 ℃）。而在添加剂的情况下没有检测到该峰。此外，分析了治疗前后样品中的DXN。结果表明，添加剂处理后的样品中DXNs的浓度下降不到1/！05相比，未经处理的一个没有添加剂。这些结果证实了这些添加剂的应用不仅具有防止粉煤灰固化的优点，而且还具有促进DXN分解的优点。少