德士古气化炉气化反应过程的数值模拟与特性分析

Numerical Simulation and Characteristic Analysis of the Gasification Process for a Texaco Gasifier

利用Fluent软件对德士古水煤浆气化炉进行数值模拟仿真。用Finite Rate/Eddy-Dissipation(有限速率/涡耗散)模型求解气化过程;用Standard k-ε湍流模型封闭动量方程;用DPM(离散相)模型设置并求解煤粉燃烧的多步焦炭反应;用P-1辐射模型模拟气化炉内辐射特性。通过比较模型预测的数据与工业数据的差别,证实了模型的有效性。在此模型基础上考察了煤浆流量、氧气流量和煤浆浓度三者之间的耦合关系和中心氧体积分数对出口气体组成、有效气产率、温度及碳转化率的影响规律,为提高煤气有效成分、碳转化率和保证生产安全提供参考依据。

Coal gasification technology has played an important role in coal development and utilization approaches of coal.Texaco gasifier,as a representative of the mature gasifier,is purchased by most of the enterprises to carry out industrial production.In order to improve the gasification process,detailed numerical simulation is necessary.Based on Fluent software,numerical simulation of the coal gasification process for a Texaco gasifier was investigated with a comprehensive model.Previous geometric model of gasifier payed more attention to simple two-dimensional rectangle shape,and ignored the effect of nozzle and spherical head on the flow field of the gasifier.In addition,previous researches mainly focused on the method of probability density function,while it was hard to use non-premixed combustion model to simulate the heterogeneous reactions of coke with CO 2,H 2O and other substances.Therefore,the distribution of the components in the gasifier can’t be well reflected.In this paper,Finite Rate/Eddy-Dissipation model was adopted to simulate the coal gasification process and DPM(Discrete Phase Model)was adopted to solve the multiple-surface-reactions of coal combustion.Compared with the non-premixed probability density function method,the results were more accurate.Standard k-εturbulent model was adopted to close the momentum equation.P-1 radiation model was adopted to simulate the internal radiation characteristics of gasifier.The validity of the model was confirmed by comparing the model prediction data with industrial data.On the basis of this model,the coupling relationship of the three factors,including the coal slurry flow rate,oxygen flow rate and coal slurry concentration was investigated.The effect of the center oxygen ratio defining as the proportion of center oxygen to total oxygen on the gas components of gasifier outlet,the efficiency of effective components,the outlet temperature and the carbon conversion ratio were investigated;A reference was provided to improve the efficiency of effective components and the carbon conversion ratio,and to ensure industry production safety.