热处理过程中城市生活垃圾氯释放特性的研究

Behavior of Chlorine in Municipal Solid Waste During Heat Treatment

采用热重和傅里叶变换红外光谱(TGA-FTIR)联用技术,研究了城市生活垃圾(MSW)在受热过程中氯的释放特性,同时考察了升温速率、气氛、加热终温等因素对氯释放特性的影响.利用自行设计的管式炉试验系统对MSW热反应过程的氯析出进行了定量测定,并研究了Na_2SO_3对MSW氯释放特性的影响.结果表明,在燃烧和热解过程中,MSW所含的氯基本上以HCl的形式释放,氯的起始释放温度随升温速率的提高而增加;在相同的升温速度下,MSW在燃烧时氯的起始释放温度比热解状态下氯的起始释放温度低.在热处理过程中,MSW灰渣中的金属氧化物可起到固氯的作用.在温度为500℃左右的情况下,持续加热30 min,MSW中70％～80％的有机氯释放出来;在1200℃下保温10～30 min,MSW中的无机氯有5％～25％释放出来.此外,MSW中含有Na_2SO_3,对无机氯的释放有促进作用.

TGA-FTIR techniques were applied in investigation on behavior of organic and inorganic sources chlorine in municipal solid waste (MSW) in thermal process, and effect of factors such as heating rate, holding time at ending temperature and additive (Na2SO3) on chlorine release was also studied. Besides, a quantity determination of chlorine release from MSW during heat treatment was carried out on a tubular electric oven. It indicates that both organic and inorganic chlorine in the MSW release in the form of HC1 during heat treatment, and initial release temperature of HC1 from MSW increased with the increase of heating rate. On comparable conditions initial release temperature of HC1 from MSW in combustion is lower than that in pyrolysis. It has been proved that some metal oxides in MSW played a role of chlorine-fixing in thermal process. Results of quantitative analysis indicate that 70% -80% of organic chlorine released when MSW was heated up to 500 'C and was held for 30 min. Meanwhile, about 5% -20% of inorganic chlorine released at 1 200 'C being held for 10 - 30 min. Apart from this, Na2SO3 in MSW can enhance the release of inorganic chlorine during heat treatment.