Thermal Stability of Zinc Compounds

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• 作者：Frida Jones ; Honghi Tran ; Daniel Lindberg ; Liming Zhao ; Mikko Hupa
• 刊名：Energy & Fuels
• 出版年：2013
• 出版时间：October 17, 2013
• 年：2013
• 卷：27
• 期：10
• 页码：5663-5669
• 全文大小：336K
• 年卷期：v.27,no.10(October 17, 2013)
• ISSN：1520-5029

文摘

Zn and Cl have been found in deposits in municipal solid waste (MSW) boilers and industrial boilers. This leads to the general belief that ZnCl₂ may play a role in corrosion of heat-transfer tubes, owing to its low melting temperature and high corrosivity. In this study, the thermal stability of the compounds ZnCl₂, ZnSO₄, and ZnO as well as mixtures of ZnCl₂ and NaCl/KCl was investigated by means of thermogravimetric analysis/differential scanning calorimetry (TGA/DSC). The reactions of the Zn compounds with SO₂/SO₃ and HCl were also investigated. The results obtained show that ZnCl₂ melts at 320 掳C. Above 400 掳C, ZnCl₂ vaporizes and is partly oxidized to ZnO. ZnSO₄ is stable up to 680 掳C, at which it decomposes and, subsequently, forms ZnO above 900 掳C. ZnO is stable at a much higher temperatures but can be chlorinated to ZnCl₂ in the presence of HCl at temperatures around 300 掳C. In the presence of a large amount of NaCl/KCl, which is typically the case in actual boilers, ZnCl₂ reacts with NaCl/KCl to form 2NaCl路ZnCl₂ and 2KCl路ZnCl₂, respectively. These compounds melt at temperatures lower than NaCl and KCl but higher than ZnCl₂. The findings show the significance of understanding the thermal stability of various zinc compounds, how they interact with one another, and whether they react with alkali chlorides and other compounds in the deposits to assess the role of Zn in deposit formation and corrosion in boilers burning Zn-containing fuels.