基于高光谱成像分析的煤焦高温燃烧机理研究

The effective on-line measurement of the time-varying parameters, such as char particle temperature, particle size, volume fraction, is very important for a further understanding of the char combustion mechanism and developing calculation model during the suspended char combustion process . This study aims at investigating the radiative properties of char combustion in the visible and near-infrared spectral region and obtains the visual information of particles of the three-dimensional temperature, volume fraction, and distributions of particle diameters when the char burns. At first, based on the model of char structure and effective medium theory, the transmission spectrum method is introduced to get the char optical constant under arbitrary burn-off degree. Then, on the basis of hyperspectral and high temporal resolution imaging technology combined with inverse radiative problem strategy in a flat flame furnace and a one-dimensional furnace, the non-uniform three-dimensional temperature field, radiative properties of particles, volume fraction of particles and particle diameter distributions will be reconstructed in the pulverized coal flame. Lastly, this study will focus on the effect of these quantitative detecting parameters on the char combustion process and it will perfect the chemical reaction kinetics model of char combustion, improve the forecasting accuracy of reaction rate, and promote the development of research on the char combustion.

煤粉悬浮燃烧过程中煤焦颗粒温度、尺寸和浓度等分布参数随时间演化特性的有效在线检测，对于深入认识煤焦燃烧机理、发展计算模型尤为重要。本项目从煤焦燃烧的可见光/近红外光学辐射特性检测分析入手，得到煤焦燃烧过程三维非均匀粒子温度、浓度及粒径分布等信息。首先，在煤焦燃烧结构模型和有效介质理论基础上，利用光谱透射法得到任意燃尽度煤焦光学常数；然后，在平焰炉/一维炉中结合高光谱、高时间分辨率成像技术及辐射逆问题解耦策略，同时重建煤粉火焰中颗粒物三维非均匀温度、辐射特性参数、颗粒物浓度及粒径分布；最后，着重探讨这些定量检测参数对煤焦燃烧机理的影响，完善煤焦燃烧反应动力学模型，提高煤焦反应速率预报精度，促进煤焦燃烧反应机理的发展。

基于图像和光谱的煤粉燃烧过程中煤焦颗粒温度、尺寸和浓度等分布参数在线检测技术研究，对于火焰燃烧温度和浓度测量技术发展，以及深入认识煤焦燃烧过程有着非常重要的意义。本项目首先建立了准直光入射煤灰及煤焦粒子系透射特性的正逆问题计算模型，理论分析粒子不同吸收系数、散射系数、样品厚度对粒子辐射特性反演结果的影响。然后，在实验室小型乙烯火焰中开展温度场、辐射特性参数、粒子浓度及尺度参数反演算法的实验验证研究。最后，在平焰炉上使用CCD、高光谱仪及高速摄像仪检测煤焦火焰图像，同时反演粒子温度、辐射特性参数、浓度和粒径分布，并将采样参数与反演检测结果比较验证，探究了煤焦燃烧定量检测参数对燃烧机理的影响。本项目开展的基于高光谱成像的温度场和浓度场测量检测技术将促进火焰非接触被动测量技术的发展；同时，煤焦燃烧过程温度场和浓度场检测对于完善煤焦燃烧反应动力学模型，提高煤焦反应速率预报精度，促进煤焦燃烧反应机理的发展提供了定量检测及验证手段。