The ignition and combustion of coal particle groups are investigated numerically in a laminar flow reactor. The Flamelet Generated Manifold method is extended to account for the complex mixture of gases being released during devolatilization, which is calculated with a competing two-step model. A second mixture fraction is introduced to include the mixing with the second methane fuel stream. The interactions of the gas phase with particles are modeled within a fully coupled Euler-Lagrange framework. To investigate the influence of particle groups on ignition and combustion, successively increasing densities of particle streams have been analyzed. The ignition delay time is increased significantly by higher particle densities. This delay is validated successfully with the available measurements. Moreover, the shape of the volatile flame was found to be strongly influenced by the particle number density inside the flame. A transition from spherical flames around single particles to a conical flame around the particle cloud could be found in numerical results as well as in experiments. As the primary mechanism for the substantial ignition delay and the formation of the flame, the increased heat transfer from the gas-phase to the particle group, resulting in lower gas-phase temperatures, was identified.

在层流反应器中对煤颗粒群的着火和燃烧进行了数值研究。扩展了“火焰产生歧管”方法，以解决脱挥发分过程中释放出的复杂气体混合物，这是通过竞争的两步模型计算得出的。引入第二混合物级分以包括与第二甲烷燃料流的混合。在完全耦合的Euler-Lagrange框架内模拟了气相与粒子的相互作用。为了研究粒子群对点火和燃烧的影响，已经分析了粒子流的连续增加的密度。较高的颗粒密度可显着增加点火延迟时间。此延迟已通过可用的测量成功验证。而且，发现挥发性火焰的形状受火焰内部颗粒数密度的强烈影响。在数值结果和实验中都可以发现从单个粒子周围的球形火焰到粒子云周围的锥形火焰的过渡。作为引起大量点火延迟和形成火焰的主要机制，人们已确定了从气相到颗粒组的传热增加，从而导致了较低的气相温度。