The Research Of The Push-pull Ventilation System About Large-scale Sludge Compositing Fermentation Tank

With the rapid increase of urban sewage, the treatment of the sewage in sludge which is concerned in our country has became a big problem.beacuse of the low efficiency of trapping stench gas, this technology has became difficult to be popularized. This paper take a sludge treatment plant in zhengzhou city as the background, study the stench capture of the sludge composting fermentation.Now the form of exhaust system commonly used in the fermentation workshop include upper exhaust hood, inductive ventilation and general ventilation, but the push-pull ventilation system is not applied in practical engineering applications on a single fermentationtank. The push-pull ventilation system is commonly used in industrial tank, the design and calculation methods of such a large scale fermentation tank used as paroxysmal sources trough are have to be studied in the future, and this is the issue of the research.First of all, through the introduction of the flow field theory of push-pull ventilation, analysis and compare the existing push-pull ventilation system theoretical calculation method, summed up the scope of application and characteristics of each method. Secondly, in this paper take engineering background for example, using existing push-pull ventilation system theoretical calculation method to calculate, for the calculated result, each parameter value set up different the working condition. Finally, using the CFD numerical simulation technology to establish the geometric model of fermentation tank, the model of breathing push-pull ventilation system on single fermentation tank is finished and analysed.This paper’s mainly research conclusion is as follows:1、 in view of the existing several related push-pull ventilation design calculation method, simulating the calculation results corresponding to different working conditions, and analysising the main pollution gas concentration distribution contours and the velocity distribution chart, find the push-pull ventilation calculation method which can be used to calculate in the large scale sludge fermentation tank, as a result, the new flow ratio method is suitable for the engineering application;2、 Through optimize the design of the result of the new flow ratio method to calculate the working condition, change the influence factors of push-pull ventilation system, set up and simulate different working conditions, compare those simulation results that the best parameters of capture odor, it is concluded: best blow mouth along from the groove surface distance is 0.5 m, under the best absorb along the groove surface distance is 0.3 m, the best flow Angle alpha is 20 °, the small new flow ratio is 0.4.3、 in this kind of large scale fermentation tank set up double sides push-pull ventilation system, compared to single side push-pull ventilation system optimum condition of gas capture efficiency, it is concluded that single side push-pull ventilation system is better than double sides push-pull ventilation system.