采用颗粒停留时间分布表征炉内颗粒流动,建立了一种考虑了炉体结构、颗粒粒径以及煤焦反应动力学的气流床气化炉综合模型,其中包含了煤脱挥发份、均相反应、非均相反应、气-固相能量方程、相间传热等子模型。模拟结果与多喷嘴对置式水煤浆气化炉工业运行数据吻合良好,考察了气相组分、温度以及不同粒径颗粒的碳转化率和温度在炉内的一维无因次分布。对模拟结果的分析表明:煤颗粒的预热、脱挥发份和燃烧过程在约30 ms内完成,气化过程占颗粒反应历程的绝大部分;气化炉内100μm以下的小颗粒升温速率快,且温度较高,碳转化率基本接近100%;而200μm以上的大颗粒升温速率较慢,碳转化率较低,影响了气化炉整体碳转化率。
With taking the effects of gasifier structure,particle size and reaction kinetics on gasification results into account,a comprehensive model of entrained flow gasifier was developed in this study,in which the particle residence time distribution was employed to characterize the particle flow behavior.Submodels of coal devolatilization,homogeneous and heterogeneous reactions,energy balance and heat transfer were included in this model.The simulation results of an OMB(opposed multi-burner) gasifier are in well agreement with industrial operating data.1-D distributions of gas components,temperature and total carbon conversion in gasifier were obtained.Additionally,profiles of temperature and carbon conversion of particles with different diameters along normalized gasifier length are included as well.Following results can be observed quantitatively: Preheating,devolatilization and combustion of coal particles are completed in about 30 ms.Gasification of particle is the major process in gasifier.Small particles are heated rapidly and converted completely because of having high heat transfer and reaction rate.Carbon conversion ratio of the particles smaller than 100 μm reaches about 100% at the outlet of gasifier.However,for the particles larger than 200 μm,their temperature increases slowly and carbon conversion ratio is relatively lower.