The Simulation And Optimization Of UASB Reactor Based On CFD

UASB reactor is the most widely used anaerobic reactor in the field of wastewater treatment.As the key component of Upflow Anaerobic Sludge Blanket(UASB), the structure of three-phase separator has a directly influence on the separation of gas-liquid-solid. So the reasonable size, appropriate structure not only separates gas from the other two phase effectively, but also forms appropriate flow pattern in the sedimentation area, this flow pattern can make a good separation of liquid and sludge finally. In addition operating conditions has some influence for the operation of entire reactor and three-phase separation.The paper focus on optimal design of the structure of three-phase separator, simulates several common structure of three-phase separator firstly. Then according to the result of simulation, the paper proposes the improvement program of structural, and simulates the improvement structural, depending on the simulation, we discuss the improvement of rationality. The results show that the disadvantage of the three common three-phase separator is that short area is too large, gas separation of some structure is sufficient. So we improve the structure of three-phase separator, simulate the improved structure, according to the result of simulation, we can conclude that the improved structures can solve the problem of short zone, as to the problem of sufficient of gas separation, the effect of improved structure in not obvious.Then aim at the dimensions of some kind of structure of the three-phase separator, in this paper,we change the size of three-phase separator, simulate the flow pattern of UASB with different size three-phase separator by using the Fluent software, analyze gas volume fraction of the variation of size, choice suitable dimensions. The results show that greater the overlap portion of the horizontal projection of the upper and lower triangular gas chamber and the better the effect of gas separation, the conclusion is the size of the horizontal projection region with the size of the region of the short region is disproportionate. At last from the aspect of sludge flow pattern, we explore the optimal value of operations when the reactor runs normally and effectively. The results show that if inlet velocity and sludge concentration is too small, the sludge can not be successfully into the precipitation zone, the sludge will be accumulated around the three-phase separator which hind the gas separation. If inlet velocity and sludge concentration is too large, the sludge will lead to loss.The conclusion of this paper help us have a fully realize on the UASB reactor internal flow field with the factors of variation, which is used to guide the actual engineering optimization and efficient operation. It has some significance for enterprise energy-saving and profit improvement.