钱大益, 王艳, 邢奕, 金明辉, 苏伟, 张梦然, 郑跃博, 刘媛梦, 段淑雅. 烧结半干法脱硫灰中亚硫酸钙氧化特性[J]. 工程科学学报, 2023, 45(11): 1985-1996. DOI: 10.13374/j.issn2095-9389.2022.09.19.004
引用本文: 钱大益, 王艳, 邢奕, 金明辉, 苏伟, 张梦然, 郑跃博, 刘媛梦, 段淑雅. 烧结半干法脱硫灰中亚硫酸钙氧化特性[J]. 工程科学学报, 2023, 45(11): 1985-1996. DOI: 10.13374/j.issn2095-9389.2022.09.19.004
QIAN Dayi, WANG Yan, XING Yi, JIN Minghui, SU Wei, ZHANG Mengran, ZHENG Yuebo, LIU Yuanmeng, DUAN Shuya. Oxidation characteristics of calcium sulfite in sintering desulphurized ash[J]. Chinese Journal of Engineering, 2023, 45(11): 1985-1996. DOI: 10.13374/j.issn2095-9389.2022.09.19.004
Citation: QIAN Dayi, WANG Yan, XING Yi, JIN Minghui, SU Wei, ZHANG Mengran, ZHENG Yuebo, LIU Yuanmeng, DUAN Shuya. Oxidation characteristics of calcium sulfite in sintering desulphurized ash[J]. Chinese Journal of Engineering, 2023, 45(11): 1985-1996. DOI: 10.13374/j.issn2095-9389.2022.09.19.004

烧结半干法脱硫灰中亚硫酸钙氧化特性

Oxidation characteristics of calcium sulfite in sintering desulphurized ash

  • 摘要: 针对烧结半干法脱硫灰中CaSO3在不同反应条件下干热氧化的变化规律,研究了温度、气体中O2含量与流速、钙类化合物、铁氧化物(Fe2O3)、水蒸汽含量与流速等对CaSO3氧化的影响. 结果表明:反应遵循阿累尼乌斯方程,在空气氛围,升温速度为10 ℃·min–1的条件下,450 ℃、75 mL·min–1的气体流速为经济性干热氧化的最佳工艺条件,水汽对CaSO3氧化反应具有两面性;钙的氧化物对CaSO3氧化反应通过抑制 \textO_\text2^- \textS\textO_\text3^- 自由基的生成而抑制反应进行,3种钙类氧化物对CaSO3氧化抑制作用从弱到强为:CaCO3<Ca(OH)2<CaCl2;Fe2O3对CaSO3的催化作用随温度、浓度变化而改变,温度小于450 ℃,Fe2O3质量分数大于0.2%时,对氧化反应起到一定催化作用,温度大于450 ℃及催化剂质量分数低于0.2%时,由温度占主导地位. 微观形貌表征显示随着CaSO3被氧化为CaSO4,形貌由团簇状转变为柱状,CaCl2即抑制氧化反应也抑制CaSO4的晶型,Fe2O3促进CaSO4结晶的形成. 实验室升温较快,温度大于400 ℃时,脱硫灰5 min内部温度大于500 ℃,此时,CaSO3转化率超过85%,中试升温较慢,没有这一特征;吉布斯自由能计算结果表明最有可能发生的是CaSO3氧化反应,600 ℃以下钙的分解反应不可能发生;CaSO3氧化过程中活性位点的数量与温度有关,当温度在623~723 K时,该反应为一级反应,当温度大于723 K时,反应在5 min左右迅速完成,无法确定其反应级数.

     

    Abstract: Considering the variation in dry heat oxidation of CaSO3 in sintering semidry desulfurization ash under different reaction conditions, the effects of temperature, O2 content and flow rate in gas, calcium compounds, iron oxide (Fe2O3), water vapor content, and flow rate on CaSO3 oxidation were evaluated. It was determined that the reaction adheres to the Arrhenius equation. The oxidation rate of CaSO3 increases from 380 ℃. Moreover, at 450 ℃, the oxidation rate of CaSO3 exceeds 90%, and at 550 ℃, it is completely oxidized (98.2%). Under the condition of 10 ℃·min−1 in the air atmosphere, the gas flow rate of 450 ℃ and 75 mL·min−1 is the optimal process condition for economic dry heat oxidation. Water vapor is present on both sides of the CaSO3 oxidation reaction. Moreover, the oxidation of CaSO3 by calcium oxides was inhibited by inhibiting the generation of \textO_\text2^-\;\textand \;\textSO_\text3^- free radicals. The order of the inhibition of CaSO3 oxidation by the three calcium oxides from weak to strong was CaCO3 < Ca(OH) 2 < CaCl 2. The catalytic effect of Fe2O3 on the oxidation of CaSO3 varies with temperature and concentration. When the temperature is less than 450 ℃ and the weight percentage of Fe2O3 is greater than 0.2%, it plays a certain catalytic role in the oxidation reaction. The doping of Fe2O3 accelerates the formation of \textO_\text2^- and \textS\textO_\text3^- free radicals. When the temperature exceeds 450 ℃ and the catalyst concentration is less than 0.2%, the catalyst concentration has no effect on the reaction process, and the temperature takes precedence. The microscopy analysis reveals that with the oxidation of CaSO3 to CaSO4, the morphology shifts from cluster to column. Furthermore, CaCl2 inhibits not only the oxidation reaction but also the crystal form of CaSO4. Fe2O3 aids the formation of CaSO4 crystals. When the temperature exceeds 400 ℃, the internal temperature of desulfurized ash is higher than 500 ℃ for 5 min. Simultaneously, the conversion rate of CaSO3 is greater than 85%, and the pilot test temperature is slower, which lacks this feature. The Gibbs free energy calculation results show that the most likely reaction is the oxidation of CaSO3 and that decomposition of calcium below 600 ℃ is not feasible. The number of active sites in the process of CaSO3 oxidation is proportional to temperature. Thus, when the temperature is between 623 and 723 K, the reaction is a first-order reaction. When the temperature exceeds 723 K, the reaction will be completed quickly in about 5 min, and the reaction order cannot be determined.

     

/

返回文章
返回