Influence of the release and combustion of volatiles on char reactivity of solid fuels

目前的项目研究挥发性释放和点火条件对固体燃料燃烧后的影响，后者是热转化过程的时间决定因素。在许多研究活动中对炭燃烧进行了研究。确定煤焦燃烧速率参数的实验，已经用未加工的燃料进行了，在煤焦燃烧之前的实验中进行了脱挥发，或者用单独制备的煤焦进行了实验，从而在不同条件下的实验中获得了类似的煤焦性质。众所周知，生产条件、加热速率、温度和终温保温时间对固体燃料炭的反应性有影响。由于挥发物的点火影响颗粒边界区域的热条件，在技术装置中挥发物通常不会从炭燃烧过程中分离出来，因此必须对这种影响进行实验研究。本项目旨在研究挥发性燃烧和点火对固体燃料炭反应性的影响。典型的粉状燃料（煤和生物质）将在实验室规模的反应堆中燃烧。研究了dp= 100 μ m的特征粒径，并模拟了应用大气中不同氧含量的现实条件。点火过程将通过光学方法（化学发光，用新开发的相机系统成像热法）和固体取样来表征。这可以确定随时间的点火过程和剩余固体（炭）。点火实验的结果用于确定炭取样的位置。这些样品稍后将被重新点燃，以研究在相同燃烧气氛下不同点火条件下的炭样。利用新开发的相机系统，通过测量颗粒温度和直径来表征炭的反应性。温度和直径数据将用于计算焦炭燃烧动力学参数。这些参数将用于确定点火和脱挥发条件对后续炭燃烧过程的影响。

The current project investigates the influence of volatile release and ignition conditions on the following char burnout of solid fuels, the latter being time-determining for the thermal conversion process. Char combustion has been investigated in many research activities. Experiments, which determine char combustion rate parameters, have been carried out with unprocessed fuels, devolatilizing in the experiment prior to char combustion, or with separately prepared char, leading to comparable char properties for experiments under varying conditions. It is a well-known fact, that the production conditions heating rate, temperature and holding time of the final temperature affect the reactivity of solid fuel chars. As the ignition of volatiles, which is typically not separated from the char combustion process in technical devices, influences the thermal conditions in a particles boundary region, this influence has to be investigated experimentally.This projects aims to investigate the influence of volatile combustion and ignition on the reactivity of solid fuel chars. Typical pulverized fuels (coals and biomass) will be burned in a lab-scale reactor. Characteristic particle sizes of dp= 100 µm are investigated, with varying oxygen content in the applied atmospheres realistic conditions will be simulated. The ignition process will be characterised by optical methods (chemiluminescence, imaging pyrometry with a newly developed camera system) and solid sampling. This enables to determine the time-dependent ignition process and the remaining solid (char). The results from the ignition experiments are used to define positions for char sampling. These samples will be re-fired later on to investigate char samples from different ignition conditions in equal combustion atmospheres. Char reactivity is characterized by measurement of particle temperature and diameter with the newly developed camera system. The temperature and diameter data will be used to calculate char burning kinetics parameters. These parameters will be used to identify the influence of ignition and devolatilization conditions on the subsequent char combustion process.