Research And Optimization For The Ability Of Foam Removing Of Tow-stage Annular Mechanical Foam Breaker

This paper mainly focuses on the technical difficulties such as the difficulty of defoaming and the non recycling of the foam fluid.Based on the Coanda principle,a two-stage annular mechanical foam breaker is designed.When the foam breaker is in operation,high-pressure gas flows from the intake pipe into the two-stage annular nozzle at high speed,respectively,and the narrow,thin,high-velocity air jet flows close to the inner wall of the foam breaker due to the Coanda effect.Under the entrainment effect of the high-speed airflow,the surrounding gas flows continuously to the wall,and a large vacuum area formed near the wall and behind the nozzle.When the foam flows through this area,it expands and ruptures due to the pressure difference between the inside and outside.In addition,due to the high kinetic energy of the wall-mounted airflow,in addition,due to the high kinetic energy of the wall-mounted airflow,when the foam fluid passes through the throat and the rear spray body,low-energy foam fluids come in contact with the high-speed,wall-mounted airflow and exchange energy.A large shear force is generated in the working chamber to shear-break the unbroken foam.The defoamed foam fluid gradually decreases in speed as it flows through the diffuser,pressure gradually returns to normal pressure.Therefore,the two-stage annular mechanical foam breaker mainly uses two functions of negative pressure expansion and shearing to defoam,and the foam-breaking effect is more significant than other vacuum foam breaker.In order to improve the foam-breaking effect of the two-stage annular mechanical foam breaker,the following studies were mainly conducted in this paper:Inventor software was used to establish a two-stage annular mechanical foam breaker model.FLUENT software was used to simulate the internal flow field of the two-stage foam breaker to analyze the airflow velocity and negative pressure.The influence of key structural parameters such as the length of the throat,the angle of the diffuser,the length of the diffuser and the radius of curvature of the two-stage annular nozzle on the internal flow field of the defoamer was analyzed and studied.Thesimulation results showed that the average negative pressure and the average airflow velocity in the critical area reached the maximum when the throat length L2=40mm,the diffuser angle?=6°,the diffuser length L3=350mm,the radius of curvature of the two-stage Laval nozzle R=110mm.In order to further verify the foam-breaking effect of the two-stage annular mechanical foam breaker,the experiment table was established.The effects of foam gas-liquid ratio,foam fluid half-life and air supply pressure in the air compressor on the foam-breaking efficiency were tested experimentally.The experimental results show that the two-stage annular mechanical foam breaker has good foam-breaking ability pand the foam elimination effect is significant.The foam-breaking efficiency in the experiment is up to 82%.Even if the foam half life is 86 min,the foam-breaking efficiency can reach 60%.