The effects of temperature and oxygen content on the PCDD/PCDFs formation in MSW fly ash.
The effects of temperature and oxygen content on the PCDD/PCDFs formation in MSW fly ash.
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DOI：
10.1016/s0045-6535(99)00227-1
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发表时间：
2000
期刊：
影响因子：
8.8
通讯作者：
M. B. Chang;T. Huang
中科院分区：
文献类型：
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作者：
M. B. Chang;T. Huang
在这项研究中，温度的影响，氧气含量的气流和灰颗粒中的碳含量对二恶英/Fs在飞灰表面的形成进行了研究。二恶英形成的最佳温度分别为锅炉灰350°C、旋风除尘器灰300°C和电除尘器灰250°C。初步结果表明，最佳温度将随着颗粒尺寸的减小而降低。当O2浓度在0%~ 100%范围内变化时，旋风灰中生成PCDD/Fs的最佳氧含量为7.5%，且PCDD/PCDF比值随氧含量的增加而增大。即使不含氧的气体通过飞灰，也观察到二恶英的形成。因此，其他反应路线，不需要O2二恶英的形成发生在粉煤灰。在本研究中，飞灰中的碳含量在0%和20%之间变化，并且结果表明，在5%时发现二恶英的形成最大。在所有的形成实验中，前体都没有注入飞灰或气流中，然而，二恶英仍然在飞灰中形成。因此，除了迪肯反应，其他氯化途径可能会发生在飞灰表面。
In this study, the effects of the temperature, oxygen content in the gas stream and carbon content in ash particles on PCDD/Fs formation on the fly ash surface were investigated. The optimum temperatures for dioxin formation were found at 350°C for boiler ash, 300°C for cyclone ash and 250°C for ESP ash, respectively. Preliminary results indicate that the optimum temperature will decrease as the particle size decreases. When the O2concentration is varied between 0% and 100%, the optimum oxygen content for PCDD/Fs formation is found to be at 7.5% for cyclone ash, and the PCDD/PCDF ratio increases with the increase of oxygen content. Dioxin formation is observed even for the gas containing no oxygen passed through the fly ash. Hence, other reacted routes that do not need O2for dioxin formation take place on fly ash. The carbon content in fly ash is varied between 0% and 20% in this study, and the results have indicated that the maximum dioxin formation is to be found at 5%. The precursors are not injected into the fly ash or gas stream in all formation experiments, however, dioxin is still formed in fly ash. Consequently, other chlorinated routes besides Deacon reactions may take place on the fly ash surface.