OPTIMIZATION SIMULATION STUDY OF HEATING STIRRING SYSTEM FOR BIOGAS ENGINEERING FEEDING TANKS
The heating stirring system can improve the temperature and uniformity of the biogas slurry in the biogas feeding tanks,and effectively increase the biogas production.In order to study the effect of the heating stirring system on the temperature distribution of the biogas feeding tanks,using the computational fluid dynamics,the physical model was established on a square feeding tank,which was covered with hollow polycarbonate panels in a cattle farm in Tangshan.The temperature distribution of biogas slurry was optimized by using different water supply modes of helical heating coil tube heat exchangers,different operation modes and obliquity angles of agitators,and square or circle of tank body shape.The reliability of the model is verified by comparing the simulated and measured data.Finally,the temperature cloud diagrams were drawn on the base of section X=0,and the biogas slurry temperature was divided into low temperature zone,middle temperature zone and high temperature zone according to different intervals.The results show that the heating coil adopts the form of lower supply and upper return,which is beneficial to the temperature rise of biogas slurry and can eliminate the low temperature zone and increase the proportion of the middle temperature zone from 92.15% to 98.01%,with an increase of 6.4% .The agitators can improve the uniformity of the temperature.On this basis,using two agitators with different steering can increase the proportion of high-temperature zone from 1.99% to 5.26%,with an increase of 166% .The inclined angle of agitators should not be set too large,45°is a suitable angle.Under the same heating conditions and agitator parameters,the proportion of low and high temperature zone is close between square tank and circular tank,but the proportion of middle temperature zone of circular tank is 2% more than that of square tank.The proportion of medium temperature zone is higher,the mixing dead zone is smaller and the mixing effect is better.
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