Janković Bojan, Janković Marija, Mraković Ana, Krneta Nikolić Jelena, Rajačić Milica, Vukanac Ivana, Sarap Nataša, Manić Nebojša
"Vinča" Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovića Alasa 12-14, P.O. Box 522, 11001 Belgrade, Serbia.
Faculty of Mechanical Engineering, Fuel and Combustion Laboratory, University of Belgrade, Kraljice Marije 16, P.O. Box 35, 11120 Belgrade, Serbia.
Materials (Basel). 2024 Nov 25;17(23):5759. doi: 10.3390/ma17235759.
Thermal decomposition (pyrolysis) of coal bottom ash (collected after lignite combustion in coal-fired power plant TEKO-B, Republic of Serbia) was investigated, using the simultaneous TG-DTG techniques in an inert atmosphere, at various heating rates. By using the XRD technique, it was found that the sample (CBA-TB) contains a large amount of anorthite, muscovite, and silica, as well as periclase and hematite, but in a smaller amount. Using a model-free kinetic approach, the complex nature of the process was successfully resolved. Thermodynamic analysis showed that the sample is characterized by dissociation reactions, which are endothermic with positive activation entropy changes, where spontaneity is achieved at high reaction temperatures. The model-based method showed the existence of a complex reaction scheme that includes two consecutive reaction steps and one single-step reaction, described by a variety of reaction models as nucleation/growth phase boundary-controlled, the second/-th order chemical, and autocatalytic mechanisms. It was established that an anorthite 1 phase breakdown reaction into the incongruent melting product (CaO·AlO·2SiO) represents the rate-controlling step. Autocatalytic behavior is reflected through chromium-incorporated SiO catalyst reaction, which leads to the formation of chromium(II) oxo-species. These catalytic centers are important in ethylene polymerization for converting light olefin gases into hydrocarbons. Adiabatic prediction simulations of the process were also carried out. Based on safety analysis through validated kinetic parameters, it was concluded that the tested sample exhibits high thermal stability. Applied thermal treatment was successful in promoting positive changes in the physicochemical characteristics of starting material, enabling beneficial end-use of final products and reduction of potential environmental risks.
研究了塞尔维亚共和国TEKO - B燃煤电厂褐煤燃烧后收集的煤底灰的热分解（热解）过程，采用同步热重 - 微商热重技术，在惰性气氛中，以不同加热速率进行研究。通过X射线衍射（XRD）技术发现，该样品（CBA - TB）含有大量钙长石、白云母和二氧化硅，以及少量方镁石和赤铁矿。采用无模型动力学方法成功解析了该过程的复杂性质。热力学分析表明，该样品的特征在于解离反应，这些反应是吸热的，具有正的活化熵变化，在高反应温度下实现自发反应。基于模型的方法表明存在一个复杂的反应方案，该方案包括两个连续反应步骤和一个单步反应，由多种反应模型描述，如成核/生长相边界控制、二级/一级化学反应和自催化机制。已确定钙长石1相分解为不一致熔融产物（CaO·AlO·2SiO）的反应是速率控制步骤。自催化行为通过掺入铬的SiO催化剂反应体现，该反应导致形成铬（II）氧物种。这些催化中心在乙烯聚合中对于将轻质烯烃气体转化为烃类很重要。还对该过程进行了绝热预测模拟。基于通过验证的动力学参数进行的安全分析得出结论，测试样品具有高的热稳定性。所应用的热处理成功促进了起始材料物理化学特性的积极变化，使最终产品能够得到有益的最终用途并降低潜在的环境风险。
