甲醇制烯烃工艺催化剂再生过程的CFD-DEM模拟

CFD-DEM simulation of catalyst regeneration in methanol to olefins process

为了合理控制甲醇制烯烃工艺系统(DMTO)中流化床催化剂再生器的积碳燃烧反应,利用计算流体力学(CFD)将再生化学反应动力学方程耦合到离散单元模型(DEM)中,使用CFD-DEM模型对催化剂再生过程进行了拟二维和三维数值模拟;分别从再生催化剂的颗粒流型、颗粒属性、积碳分布和再生器的气体组分等方面考察了不同进气气速对催化剂再生过程的影响。结果表明:随着进气气速的增大,再生催化剂颗粒的流化速度加快,积碳分布由宽变窄,颗粒整体的流化状态趋于均匀;再生催化剂的积碳量随着时间增加而减少,随进气气速的增大而减少速率加快;催化剂密度随反应时间的增加而略有减小;随着进气气速的增大,再生反应达到平衡状态所需的时间会大幅缩短;当进气气速大于0.05 m/s时,氧气可以很快达到饱和。

In order to reasonably control the combustion reaction of carbon deposition in fluidized bed catalyst regenerator of methanol to olefin process system,the regeneration kinetics of chemical reaction equation was coupled to the discrete element model(DEM)using computational fluid dynamics(CFD).The simulated two-dimensional and three-dimensional simulation of the catalyst regeneration process was carried out using CFD-DEM model.The influence of different inlet gas velocities on catalyst regeneration process was investigated from the aspects of particle flow pattern,particle property,carbon distribution and gas composition of regenerator.The results show that with the increase of inlet gas velocity,the fluidization rate of the regenerated catalyst particles is accelerated,the carbon distribution is narrowed,and the fluidization state of the whole particles tends to be uniform.The carbon mass fraction of the regenerated catalyst decreases with the increase of time and decreases with the increase of inlet gas velocity.The catalyst density decreased slightly with the increase of reaction time.With the increase of the inlet gas velocity,the time needed for the regeneration reaction to reach the equilibrium state will be greatly shortened.When inlet gas velocity is greater than 0.05 m/s,oxygen can quickly reach saturation.