麦尔兹窑内移动床层间煤粉的燃烧特性及石灰石分解反应规律研究

Maerz kilns are wild used to produce active lime due to its high-usage of fuel and lower energy consumption. The present project focuses on the phenomenon of “over burn” or “ lack burn” in the process of the production of the active lime in the Maerz kilns and investigates the pulverized coal combustion in the gap with high concentration of carbon dioxide environment. Combustion processes of pulverized coal in moving reaction bed and decomposition of limestone in bed layer under the condition of unsteady operation, i.e. alternately injection pulverized coal and regenerative preheating,will be investigated. The experimental platform of moving reaction bed with injection pulverized coal in the light of the limestone Maerz kiln will be constructed to measure the flow characteristics of gases/ pulverized coal and analyze the products of combustion of pulverized coal in the reaction bed. The model of the interaction force between gases and pulverized coal, and the model of pulverized coal and wall of gap, as well as the subscale combustion model of pulverized coal, will be developed to the mechanism of momentum and energy transfer between pulverized coal and wall of gap in bed layer. the decomposition reaction of limestone in the moving bed layer under the condition of non-uniform temperature and concentration will also be investigate. The interaction of the limestone decomposition process and the oxygen/pulverized coal/carbon dioxide system in the combustion will be revealed. And the relationship beteewn the decomposition reaction rate and the combustion rate, flue gas component, temperature will be radicated. As a result, the improvement of the knowledge associated with interacting between combustion of pulverized coal and decomposition of moving bed in nature will be promoted throught the present investigation. And the theoretical bases for controlling exactly combustion of pulverized coal and making sure the quality of lime will be established in the project.

麦尔兹窑由于其燃料使用率高、能耗低而被广泛地用来生产活性石灰。本项目针对麦尔兹窑生产活性石灰过程中出现石灰石“过烧”或“欠烧”的现象，研究煤粉在缝隙及高浓度CO2环境中燃烧反应的问题，解析移动反应床层间交替喷煤/蓄热的非定常条件下石灰石的分解反应过程。构建石灰移动反应床喷煤燃烧实验平台，分析石灰料床缝隙中燃烧产物和石灰石分解产物分布特性及气粉颗粒流动特性；建立气体-煤粉颗粒之间两相作用力模型、煤粉颗粒与复杂空间壁作用力模型和煤粉颗粒亚格子燃烧反应模型，研究煤粉颗粒群与复杂空间壁碰撞过程动量与能量传递规律及石灰石料块在非均匀流动和反应条件下的分解反应动力学特性，揭示石灰石的分解过程与O2/煤粉/CO2体系燃烧过程的相互作用规律，确立石灰分解率与燃烧速率、窑气成分和温度的关系。从本质上推动对移动反应床内煤粉/反应性床层料块间相互作用的整体认识，为正确控制煤粉燃烧过程、保证石灰质量奠定理论基础。

麦尔兹窑由于其燃料使用率高、能耗低而被广泛地用来生产活性石灰。本项目针对麦尔兹窑生产活性石灰过程中出现石灰石“过烧”或“欠烧”的现象。通过研究煤粉在缝隙及高浓度CO2环境中燃烧反应的问题，解析移动反应床层间交替喷煤/蓄热的非定常条件下石灰石的分解反应过程。从本质上推动对移动反应床内煤粉/反应性床层料块间相互作用的整体认识，对正确控制麦尔兹窑内的煤粉燃烧过程、保证石灰质量有重要的理论意义和很强的应用背景。本项目采用离散单元法研究麦尔兹窑内燃烧过程中的石灰石分解，既考虑了石灰石之间的相互作用，而且也可以根据局部的传热条件获得单个石灰石颗粒瞬时的反应情况，从而确定单个石灰石中氧化钙和碳酸钙的瞬时体积比(即反应程度)，以此为基础建立气体-煤粉颗粒之间两相作用力模型、煤粉颗粒与复杂空间壁作用力模型和煤粉颗粒亚格子燃烧反应模型，对石灰料床缝隙中燃烧产物和石灰石分解产物分布特性及气粉颗粒流动特性以及煤粉颗粒群与复杂空间壁碰撞过程动量与能量传递规律进行了研究，确立了石灰分解率与燃烧速率、窑气成分和温度的关系。同时，本项目还研究了燃烧过程中所产生的固态污染物的排放情况及量化了各工况下的碳烟微观结构及形貌特征。本项目在International Journal of Numerical Methods for Heat & Fluid Flow和International Journal of Chemical Reactor Engineering等国外重要期刊上发表SCI 收录论文4篇，获批发明专利和软件著作权各1项，培养研究生2名。