Design And Degassing Performance Of A Centrifugal Degassed Pump

In the food industry,gas would be mixed into drinks easily in stirring process,which would cause the oxidation of juice and reduce the guarantee period,so it is necessary to remove the gas in liquid.In this study,a centrifugal degassing pump was developed,which can not only separate the gas but can also transfer the fluid.CFD analyses and experimental study were carried out to analyze the degassing property and hydraulic performance of the centrifugal degassing pump.Based on the above methods,a compact sized degassing pump with excellent gas-liquid separation ability was presented.Two kinds of degassing pump were put forward in this paper,one was named as backside air suction pump and the other was named as degassing drum pump.Basically,the structure and degassing theory of the two degassing pumps were introduced.The gas-liquid pre-separation structure was adopted by the backside air suction pump to achieve initial gas-liquid separation.The gas is discharged by the vacuum system through the air holes located in the main impeller and liquid was discharged by the main impeller.On the other hand,degassing drum pump can achieve gas-liquid separation with the degassing drum.Relying on the centrifugal force and the vacuum condition inside the drum,the gas dissolved in liquid could be separated out sufficiently.Based on CFD analyses,the performance of backside air suction pump was predicted.The impact of inlet gas volume fraction,discharge pressure and flow rate were analyzed to study the degassing effect.It turned out that this pump was only available to separate gas-liquid mixed fluid with high gas volume fraction.In other words,the pump was not suitable to transfer mixed fluid with low gas volume fraction and failed to separate the dissolved gas in liquid.In order to solve low degassing capacity of the backside air suction pump,further study on gas-liquid separation principle,air exhaust method and degassing drum were completed and the degassing drum pump was introduced.CFD analyses was also adopted to compare the influences on degassing effect of different operating conditions.The results indicated that the degassing drum pump was capable of separating gas mixed in liquid with different gas volume fraction.According to the analyses of liquid ring static pressure and thickness,it was found that the reduction of inlet pressure is useful to improve the removal ability of the dissolved gas in liquid.Performance test device was established to study the performance of two degassing pumps.The experimental results of the backside air suction pump indicated that it could partly separate the gas mixed in liquid and hardly separate out the dissolved gas in liquid.The experimental study on degassing drum pump indicated that inlet pressure,flow rate and discharge pressure have a significant impact on degassing effect.In addition,it was also verified that degassing pump has significant degassing effect in actual production.The degassing pump with degassing drum could separate the free gas in liquid completely and separate the dissolved gas in liquid observably.It showed that dissolved oxygen of the degassed fluid could be reduced to less than 5ppm which can meet the production requirements.The degassing pump could separate the free gas in liquid completely and separate the dissolved gas observably in the process of transferring liquid.To some extent,the gas-liquid separation technology at present are expanded in this study,and it is of great significance for the future innovation in the application of the gas-liquid separation and liquid degassing.