Experimental Studies on Decomposing Properties of Desulfurization Gypsum in a Thermogravimetric Analyzer and Multiatmosphere Fluidized Beds

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• 作者：Zhu Miao ; Hairui Yang ; Yuxin Wu ; Hai Zhang ; Xuyi Zhang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2012
• 出版时间：April 18, 2012
• 年：2012
• 卷：51
• 期：15
• 页码：5419-5423
• 全文大小：320K
• 年卷期：v.51,no.15(April 18, 2012)
• ISSN：1520-5045

文摘

This paper proposes a new technical process to utilize flue gas desulfurization (FGD) gypsum in fluidized beds. Gypsum is stable in the inert atmosphere and instable in the reducing atmosphere. Decomposing properties of gypsum in multiatmospheres were investigated in both a thermogravimetric analyzer (TGA) and a fluidized bed reactor. Results from the TGA showed that the initial decomposing temperatures of gypsum in all reducing atmospheres are about 800 掳C; however, the ratio between CaS and CaO in the product is influenced by CO concentration ([CO]). Higher [CO] is beneficial to speeding the decomposition. The analysis of mass spectrometer showed that part of CaS was oxidized to CaO when the atmosphere was changed from the reducing one with [CO] = 2% to the oxidizing one with O₂ concentration of 0.6%, which was proved by the XRD analysis of the final product with content of CaO of 91.6%. Fluidized bed experiments were done in a hot, lab scale, bubbling reactor. Results showed that CO₂ can increase the CaO content in the product by restraining the side production of CaS significantly. After gypsum decomposition in the reducing atmosphere, a certain amount of air was injected to change the atmosphere to oxidizing, and more SO₂ was released. The present research proves that a multistage fluidized bed system with multiatmospheres is feasible for gypsum decomposition.