【摘要】：垃圾焚燒因具有減容化、無害化、資源化等優(yōu)點,成為很多國家主要的垃圾處理方式。但垃圾焚燒會引起有毒重金屬污染,嚴重制約了垃圾焚燒技術的發(fā)展和應用。本文采用理論與實驗相結合的方法,深入研究了垃圾焚燒過程中重金屬Pb、Cd的排放特性及控制方法。首先,在管式爐上考察了無機氯(NaCl)、有機氯(PVC)、不同形態(tài)的硫(S、Na2S、 Na2SO4)以及吸附劑對重金屬Pb、Cd揮發(fā)特性的影響。實驗表明,無機氯(NaCl)、有機氯(PVC)均能有效地促進Pb、Cd的揮發(fā)；無機氯(NaCl)、有機氯(PVC)中氯釋放特性不同導致其對Pb、Cd影響機理不同。不同形態(tài)S對重金屬Pb、Cd揮發(fā)特性影響不同,低溫下S、Na2S、Na2SO4對Pb、Cd揮發(fā)具有抑制作用；而高溫下S、Na2SO4會促進Pb、Cd的揮發(fā),Na2S會促進Pb的揮發(fā),但對Cd表現出相反的作用。高嶺土、沸石對重金屬Pb、Cd具有一定的吸附作用,并且既存在物理吸附又存在化學吸附,而石灰石無明顯吸附作用。其次,在小型流化床焚燒爐上對重金屬Pb、Cd在PM10中的分布特性進行了研究,將在管式爐上表現出較好吸附效果的高嶺土在小型流化床上進行吸附性能測試,并利用SEM/EDS/XRD等分析方法分析其吸附劑機理。實驗結果表明,PM10中亞微米Pb、 Cd所占比例分別達到90%、85%；添加高嶺土能夠有效控制亞微米Pb、Cd排放,對亞微米Pb、Cd的最高捕集效率分別達83%、51%；高溫下高嶺土與重金屬Pb、Cd蒸氣反應并產生共晶融化,其產物為PbO·Al2O3·2SiO2、CdO·Al2O3·2SiO2;隨溫度升高,高嶺土與重金屬的共晶融化量增加,其共融物可促進高嶺土對重金屬蒸氣的捕集,但溫度過高會導致過量共晶融化,使高嶺土的孔隙結構坍塌,捕集效率反而降低；Pb、Cd共存時,Pb會促進高嶺土與Cd的反應,Cd能夠抑制Pb與高嶺土的過量共晶融化,1000℃時Pb、Cd產生相互促進作用。最后,基于吉布斯自由能最小法原理,利用熱力學平衡計算法考察了溫度、氯、硫和吸附劑等對Pb、Cd的揮發(fā)特性影響。計算結果表明,焚燒過程中氯易于與重金屬Pb、Cd反應生成易揮發(fā)的氯化物,促進Pb、Cd的揮發(fā)；低溫段硫會抑制重金屬Pb、 Cd的揮發(fā),而高溫段影響不大。垃圾中的Na與C1、S的親和性遠強于Pb,使得Na在一定程度上抑制了S、Cl對Pb作用。CaO對Pb、Cd的吸附效果較差,Si02能夠有效地吸附Pb、Cd,而A1203僅對Cd有一定的吸附效果。
[Abstract]:MSW incineration has become the main waste disposal method in many countries because of its advantages of reducing capacity, innocuity and resources. However, garbage incineration can cause toxic heavy metal pollution, which seriously restricts the development and application of MSW incineration technology. In this paper, the emission characteristics and control methods of heavy metal Pb / CD in MSW incineration were studied by combining theory with experiment. Firstly, the effects of inorganic chlorinated (NaCl), organochlorine (PVC), (Na2SO4) and adsorbent on the volatilization characteristics of heavy metal PBH CD were investigated in a tubular furnace. The results show that inorganic chlorinated (NaCl), organochlorine (PVC) can effectively promote the volatilization of PBN CD, and the different chlorine release characteristics in inorganic chlorine (NaCl), organochlorine (PVC) lead to different mechanism of its influence on PBN CD. Different forms of S have different effects on the volatilization characteristics of heavy metal Pb ~ (2 +) CD, and the volatilization of Pb ~ (2 +) CD can be inhibited by SbNa _ 2SO _ 4 at low temperature, while the volatilization of Pb ~ (2 +) by Na _ (2) so _ (4) can promote the volatilization of Pb under high temperature, but it has the opposite effect on CD. Kaolin and zeolites have a certain adsorption effect on heavy metal Pb ~ (2 +) CD, and there is both physical and chemical adsorption, but limestone has no obvious adsorption. Secondly, the distribution of heavy metal Pb, CD in PM10 was studied in a small fluidized bed incinerator. The adsorption performance of kaolin, which showed good adsorption effect on a tubular furnace, was tested on a small fluidized bed. The mechanism of the adsorbent was analyzed by SEM/EDS/XRD and other analytical methods. The results show that the proportions of Pb and CD in sub-micron Pb10 are 90% and 850.The addition of kaolinite can effectively control the emission of Pb ~ (2 +) CD in sub-micron, and the highest capture efficiency of Pb ~ (2 +) CD in sub-micron is 833% ~ (51)%, respectively. At high temperature, kaolin reacts with heavy metal Pb ~ (2 +) CD vapor and produces eutectic melting, which is produced by PbO Al2O3 _ 2SiO _ 2-CdO Al2O3 _ 2SiO _ 2. With the increase of temperature, the eutectic melting amount of kaolin and heavy metal increases, and its inclusion can promote the capture of heavy metal vapor by kaolin. However, excessive temperature will lead to excessive eutectic melting, resulting in the collapse of the pore structure of kaolin, and the reduction of the trapping efficiency. In the presence of Pb, Pb can promote the reaction between kaolin and CD. CD can inhibit the interaction between Pb and CD at 1000 鈩，

本文編號：2193401