氫氧氯化鈣與模來石、燃煤飛灰高溫反應之研究

Reaction of CaClOH with Mullite and Coal Fly Ash at High Temperatures

黃才榜(Tsai-Bang Huang)

指導教授 ： 施信民

國立臺灣大學/工學院/化學工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01158

摘要

都市固體廢棄物焚化所產生之飛灰含有高含量的氯鹽及微量的重金屬與毒性有機物。氯鹽中的氫氧氯化鈣(CaClOH)會造成飛灰高溫熱處理時產生結塊、粘壁等問題。本研究探討將CaClOH與模來石或燃煤飛灰反應，以分解CaClOH並固定氯的可行性。
　　CaClOH暴露於環境中會吸水潮解。CaClOH/mullite或CaClOH/coal fly ash混合物於高溫反應後會生成wadalite和calcium silicate chloride固體產物以及HCl和H2O氣體產物。反應後試樣水洗後有Friedel's salt (Ca2Al(OH)6Cl•2H2O)生成。CaClOH/mullite試樣在莫耳比為2時有最高之非水溶性固體氯含量分率，最高分率隨反應溫度、圓片試樣厚度、進料氣體含水量增加而上升。CaClOH/coal fly ash於高溫反應所生成之非水溶性固體氯含量分率隨反應溫度升高、重量配比減小而上升，且不受coal fly ash種類影響。CaClOH/coal fly ash粉末試樣於相同反應條件下使用coal fly ash所得之非水溶性固體氯含量分率較使用mullite者為高。CaClOH/mullite莫耳比越高(≧2)的粉末試樣，反應後其黏結及黏壁的現象越嚴重。CaClOH/coal fly ash粉末試樣反應後皆有輕微的黏結及黏壁現象。沒有CaO存在下，700℃時CaCl2並不會與mullite反應。

關鍵字

焚化飛灰 ； 氫氧氯化鈣 ； 模來石 ； 燃煤飛灰 ； 氯鹽

並列摘要

Fly ash generated from MSW incinerator contains high contents of alkali chlorides and trace amounts of heavy metals and toxic organic chlorides. Calcium hydroxychloride (CaClOH), one of the alkali chlorides, can cause solidification of fly ash in the heat treatment at high temperatures. This work is to study the feasibility of decomposition of CaClOH and fixation of chlorine by reacting CaClOH with mullite or coal fly ash at high temperatures.
　　CaClOH deliquesced when exposed to air. CaClOH reacted with mullite and coal fly ash at high temperatures (700-800℃) to form wadalite (Ca6Al5Si2O16Cl3), calcium silicate chloride (Ca3SiO4Cl2), HCl, and H2O. Friedel's salt (Ca2Al(OH)6Cl•2H2O) was found after the reacted sample was washed with water. The distribution of total chlorine in water-soluble salts, water-insoluble salts, and gas phase were mearsured. The highest mole fraction of total chlorine in water-insoluble salts was achieved at a CaClOH/mullite mole ratio of 2; the highest fraction increased with increasing reaction temperature, increasing thickness of disc sample, and increasing water vapor content of the swept gas. When CaClOH reacted with coal fly ash, the mole fraction of total chlorine in water-insoluble salts increased with increasing temperature and with decreasing CaClOH/coal fly ash weight ratio; the source of coal fly ash did not affect the reaction. Under the same reaction conditions, coal fly ash resulted in higher mole fraction of total chlorine in water-insoluble salts than millite. Reacted powder samples of CaClOH/mullite sintered when the mole ratios ≧ 2; all those of CaClOH/coal fly ash slightly sintered. CaCl2 alone did not react with mullite at 700℃.

並列關鍵字

incineration fly ash ； CaClOH ； mullite ； coal fly ash ； chloride

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