In the food industry, it is necessary to remove the gas in liquid, in order to prevent the juice from oxidation and prolong guarantee period. At present, vacuum tanks are widely used in beverage productive process to remove air. However, the vacuum tanks are usually bulky and of high energy consumption.
In this study, the purposes of degassing pump design are: (1) effectively removing free gas and dissolved gas in liquid, (2) conveying the liquid, (3) more energy efficient than vacuum tank. In this process, numerical method is adopted to simulate the gas-liquid separation with eulerian multiphase model and population balance model (PBM) using the commercial code FLUENT.
Structures of pulp pump and gas-liquid cylindrical cyclone separator are used for reference. The degassing pump mainly consists of inlet tube, centrifuge drum, exhaust tube, impeller, volute and outlet tube etc.
The numerical simulation results show that there is a huge low pressure area in the center of the drum. Free gas and dissolved gas are separated into the low pressure region under the effect of centrifugal force and local low pressure.
Bubble diameter has a great impact on the degassing effect. PBM which considers bubbles coalescence and breakup is adopted here to calculate the diameter of bubbles. The drum diameter has an extremely influence on the inlet pressure of degassing pump. The centrifuge drum is installed in front of impeller, so pre-swirl of the fluid inside impeller inlet is strong. The hydraulic performance of pump slightly declines when centrifuge drum is added in numerical calculation.
The degassing pump is in manufacturing and will be tested in future.