The Research on the Flow Pattern Optimization of Biogas Anaerobic Digester Using CFD Method

Abstract

The biogas plant provides high-quality, clean and renewable energy, reduces carbon emission, and can sovle rural energy shortage and mitigate environmental pollution. However, it has some defects in practice, such as poor liquidity, low biogas production rate, bad discharge, which limit its wide application. The critical method for solving this problem is agitation, but the methods of agitation must be well-designed, otherwise the biogas production could not be increased, even consuming more energy. Taking advantage of computational fluid dynamics (CFD), the flowing progress of biogas fermentation material fluid in the anaerobic digesters can be reappeared, the distribution curve of flow pattern can be obtained, the visualization of flow pattern can be achieved, the features and defects of flow configuration can be differentiated on the basis of the flow pattern visualization. In this present study, one 0.5 m³ anaerobic digester was chosen and the two water configuration modes of bottom agitation and dispersed exports were analyzed by CFD. The influence of the optimal design on the flow pattern was obtained. The results show that the optimization are different under different raw material conditions. Therefore, the agitation config could be well-designed based on the flow pattern which can be visualized using CFD method. Through the demonstration of this design opitimization, this paper introduces a general method to optimize the mixing config design of biogas plants using CFD method.