【作者】 徐伟；

【导师】 史世庄；

【作者基本信息】 武汉科技大学 ， 化学工艺， 2008， 硕士

【摘要】 随着高炉大型化以及喷煤量的增加,对焦炭质量的要求越来越高,尤其是焦炭的热性质(CRI和CSR)。焦炭钝化就是采用喷洒或者是浸渍的方式对冷态焦炭进行处理,以改善焦炭的热性质。本文以工业生产焦炭为原料,采用3 %H3BO3溶液浸渍的方式对焦炭进行处理,然后按照GB/T 4000—1996对焦炭进行反应性和反应后强度的测试,发现钝化后焦炭的CRI和CSR都有不同程度的改善。用综合热失重分析仪来测定钝化前后焦炭的溶损反应率,然后运用未反应收缩核模型计算钝化前后焦炭溶损反应的各步骤阻力(外扩散,界面化学反应,内扩散),比较前后的差异得出钝化后溶损反应的控制步骤。计算结果表明:当反应温度为900℃~1000℃时,钝化前焦炭的溶损反应过程受内扩散的控制,而钝化后焦炭的溶损反应过程同样受内扩散控制;硼酸的加入对焦炭起到钝化作用,其机理在于提高溶损反应过程中的内扩散传质阻力,从而使得整个反应率降低。运用场发射扫描电子显微镜观察钝化前后焦炭(溶损反应后)的表面结构变化,其结果验证了动力学计算所得出的结论,并且当反应温度大于1100℃时,钝化后焦炭的溶损反应过程受界面化学反应控制,钝化机理也就是抑制界面化学反应。更多还原

【Abstract】 The requirement for the coke’s quality is more and more serious, especially for the thermal performance (CRI and CSR), along with the scaling up of blast furnace and increasing of the quantity of pulverized coal injection. The passivation of coke is to adopt the method of insufflation or infusion to dispose the coke under cold condition, to improve the thermal performance of coke.In this paper, the raw coke is from the industrial production and is infused in the H3BO3 solution whose concentration is 3 %. Then the determination of CRI and CSR of coke is carried out according to the GB/T 4000—1996, and the results show that the CRI and CSR are both improved in some extent. The solution loss reaction rate of coke before and after passivation is determined by using the thermo-gravimetry analyzer, and then the every step resistance of coke’s solution loss reaction before and after passivation is calculated according to unreacted shrinking core model, including external diffusion, interfacial chemical reaction and internal diffusion. The calculated results show: when the reaction temperature is between 900℃and 1000℃, the processes of coke solution loss reaction before and after passivation are both controlled by the internal diffusion and the mechanism of passivation after addition of boric acid is increasing the resistance of internal diffusion during the solution loss reaction process, so the entire rate of reaction is decreased.The field emission SEM is used to observe the superficial structure change of coke before and after passivation (after solution loss reaction). The results prove the conclusion from kinetic calculation to be right and they also show that when the reaction temperature is above 1100℃, the process of coke solution loss reaction after passivation is controlled by the interfacial chemical reaction and the mechanism of passivation is restrianing the interfacial chemical reaction.更多还原