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

本工作旨在开发一种通过在焚烧炉中添加化学物质(含硫二氧化钛)来抑制小型焚烧炉排放的二恶英(DXN)S的方法。第一年，在聚氯乙烯粉末中加入一定含量的消石灰(Ca(OH)2)，进行了废石灰不完全燃烧的实验室实验。实验表明，添加33.2wt%氢氧化钙的烧制样品中的DXNS浓度比不添加的降低了约1/10。然而，我们得出的结论是，这种向焚烧炉中添加化学品的技术不足以满足未来对Toll排放的调节，即使使用可能比Ca(OH)2更具活性的二氧化钛。因此，我们把重点放在DXNS最集中的飞灰的二次热处理上。在常规方法中，飞灰中的DXNS是一种…在低于500℃的还原气氛下，更多的再脱氯。C.添加一些化学物质，因为飞灰在500℃以上容易固化。第二年，我们研究了飞灰在高温下固化的机理，并尝试建立了防止飞灰固化的高温处理技术。将氢氧化钠(NaOH)和莫来石作为捕集飞灰中氯的添加剂，认为它有助于固化，然后将选定的化学物质按给定的比例与飞灰混合，然后在700℃的电炉中加热，发现添加了这些添加剂的飞灰在热处理后没有发生固化。此外，X射线衍射仪分析表明，加热前的飞灰中不含氯化钙(CaCl2)，而是Ca(OH)2与HCl反应的产物CaClOH，用NaOH加热的样品中检测到氯化钠(NaCl2)，莫来石处理的样品中检测到氯化钠(氯化钠)。差热分析表明，不加添加剂的样品在降温阶段(800℃左右)有一个放热峰。而添加添加剂的样品中未检测到该峰。并对治疗前后标本中的DXNS进行分析。结果表明，添加添加剂的处理样品中的DXNS浓度比不添加添加剂的样品中的DXNS浓度降低不到1/05。这些发现证实了这些添加剂的应用不仅具有防止飞灰固化的优点，而且还具有促进DXNS分解的优点。较少

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