厌氧干发酵反应器中物料流动的数值模拟

Numerical Simulation of Material Flowing in the High Solid Content Anaerobic Reactor

当干发酵物料TS>5%时,物料符合非牛顿流体特性。运用CFD的方法,对物料在厌氧干发酵反应器中的流动进行数值模拟,得到了物料在反应器中的速度场。保证反应器顶部压力3000 Pa和物料在反应器中的流动周期3天的初始条件,对TS 5.4%,TS 9.1%,TS 12.1%,TS 20%这几种物料在反应器中流动的模拟结果进行对比。保持反应器的高度以及流动边界条件不变,通过改变反应器原始模型的高径比,分析TS20%的干发酵物料在这几种反应器中的流动特性。分析结果表明:在贴近反应器壁面处,物料的流速极低,甚至出现了流动停滞,随着物料TS含量增加,反应器内部物料的平均流速降低,混合效果减弱。随着反应器高径比的增加,反应器的有效体积增大,物料在反应器中的平均流速降低,混合效果减弱。该项研究能够使我们获得发酵设备运行时物料在反应器中的速度场,以及观测出随着物料TS含量和反应器高径比的改变,物料流动状态的改变,可为实际工程中反应器的优化设计和运行效率的提高提供参考依据,对实际工程项目具有一定的指导意义。

This paper summarized the rheological properties of the manure in high solid digester. When the TS in reactor was over 5%,the manure was in accord with the non-Newtonian fluid properties. Adopting the CFD method,the numerical simulation of manure flowing in hight solid digester obtained material velocity field in the reactor. Under the condition of3000 Pa at reactor top and 3 days of flowing period,the simulated flowing of TS 5. 4%,TS 9. 1%,TS 12. 1%,TS 20%in the reactor were compared. Keeping the height and flowing boundary without change in the reactor,but changing the origin ratio of height to diameter of the reactor,the flowing characteristics of TS 20% were analyzed. The results showed that the flow rate of the manure in the area close to the digester wall was extremely low,even stagnated. With increasing of manure TS content,the average flow velocity inside the reactor decreased,the mixing effect weakened. With the increase of height to diameter ratio,the effective volume of the reactor was increased,the average flow rate of the manure in the reactor was reduced,and the mixing effect is also reduced.