Flow Field Analysis And Optimization Study Of The Interior Diversion EGSB Reactor

Water scarcity and water environment deterioration have been two urgent issuesneeding to be solved in consideration of global freshwater resources. In China, the annualdischarge of wastewater has been the highest among other countries worldwide. Muchattention has been paid on the study of high efficiency and energy saving sewage processorin the world. Due to its low cost and its energy can be recycled for other utilization,anaerobic wastewater treatment has been the focus of many researchers. To date, amongthose developed anaerobic reactors, the third generation reactor Expanded Granular SludgeBed (EGSB) is one of the outstanding reactors. However, those EGSB reactors alreadybeing used at present are mostly designed by the semi-formula of the semi-empirical, as aconsequence of which their applications are restricted. Therefore, computational fluiddynamics (CFD) theory is adopted in our research to estimate fluid mechanics parameters ofthe reactor, which is more scientific, advanced and applicable.In this study, by means of computational fluid dynamics, euler-euler double fluidmodel was used to establish CFD mathematical model to describe solid-liquid two-phaseflow effectively in EGSB reactor. With the calculation of CFD mathematical model, thisstudy presented the flow field analysis of internal structure in EGSB reactor. Furthermore,CFD mathematical model was used as the micro-raising tools to observe hydrodynamicperformance of internal diversion in EGSB reactor, saving the cost and time consumed inthe study.Using CFD simulation software, we analyzed the hydrodynamic performance of theEGSB reactor placed in the draft tube, mainly studied the impacts of the placement andtypes of draft tubes on the macroscopic flow field and the distribution of solid content rate.Through the simulation, we obtained the best height and position of the draft tube, specificresults are as follows: To simulate the flow field at tilt angle of70°,75°,80°,85°inside theEGSB reactor which was added draft tube, the tilt angle of80°was proved to be the bestangle by comparing. The flow field analysis were made respectively when the ratio ofdraft tube diameter to reactor diameter was0.50.60.70.80.9,the ratio of0.7was selected. The flow field analysis were made respectively when the height from the draft tube bottomwas2050100150200, the height of50mm was selected. The influence of draft tubespacing on the internal flow field of the reactor was little.The CFD technology can characterize the distribution and stability of the flow field inthe different regions of the reactor, the relationship between changes in the phase holdupand mass transfer. It helps to carry out the optimization design from the optimization of thehydrodynamic performance.