基于随机模拟的粉煤气化炉内温度分布分析

Analysis of the distribution of temperature in pulverized coal gasifier based on random simulation

温度是影响气化性能的核心工艺参数,对其在气化炉内的分布尽可能进行精确刻画并分析对保证气化性能维持过程安全十分重要。视温度为空间随机变量,通过建立二维随机场模型对气化炉2个纵剖面(气化炉中心和靠近炉壁)的温度分布进行随机模拟和炉内空间相关性分析。使用FLUENT仿真软件进行数值模拟并完成温度采样,然后使用矩阵分解法建立温度随机场模型并采用中心点法进行离散,对比分析了随机场模拟和确定性模拟2个纵剖面的温度分布状态以及粗煤气出口和灰渣出口的温度。通过计算不同位置温度单元的空间关联系数,进一步研究氧化还原区不同位置温度分布的空间关联性。结果表明:在随机场模拟下,气化炉两纵剖面上下出口区域的温度呈现随机分布状态,这更符合煤气化实际运行状态,较确定性模拟,两纵剖面最高温度降低,但粗煤气出口温度和熔渣出口平均温度均有所升高;进一步的温度分布空间关联性分析表明,不同纵剖面氧化区的温度分布最大空间关联程度均高于还原区,平均关联程度低于还原区,但不同区域的空间关联系数都在0.5左右,气化炉依靠自身调节温度分布来保证气化过程高效平稳进行的能力较弱,需要人为改变操作条件进行干预。

Temperature is the core process parameter affecting gasification performance,and it is important to characterize and analyze its distribution in the gasifier as accurately as possible to ensure that gasification performance and maintained the safety of gasification process.The temperature is considered as a spatial random variable,and the temperature distribution in two longitudinal profiles(center of the gasifier and near the furnace wall)of the gasifier is simulated stochastically and analyzed for spatial correlation in the furnace by building a two-dimensional random field model.Numerical simulations were carried out using FLUENT simulation software and completed temperature sampling,then the temperature random field model was built using the matrix decomposition method and discretized using the center point method,and the temperature distribution states of two longitudinal profiles of random field simulation and deterministic simulation as well as the temperatures of syngas outlet and ash outlet were compared and analyzed.The spatial correlation coefficients of temperature units at different locations are calculated to further investigate the spatial correlation of temperature distribution at different locations in the redox region.The results show that under the random field simulation,the temperatures in the upper and lower exit areas of the two longitudinal profiles of the gasifier show a random distribution,which is more consistent with the actual operation of coal gasification.Compared with the deterministic simulation,the maximum temperature of the two longitudinal profiles decreases,but the syngas outlet temperature and the average slag outlet temperature both increase.Further analysis of the spatial correlation of temperature distribution shows that the maximum spatial correlation of temperature distribution in the oxidation zone of different longitudinal profiles is higher than that in the reduction zone,and the average correlation is lower than that in the reduction zone,however,the spatial correlation coefficients of different regions are around 0.5.The ability of the gasifier to rely on its own regulation of temperature distribution to ensure efficient and smooth gasification process is weak,and human intervention is required to change the operating conditions.