Study On Gas-liquid Two-phase Distribution And Turbulent Characteristics In Scrubbing And Cooling Chamber

Liquid phase velocity and gas phase distribution play an important role in the mixing and transfer of two phases in industrial washing and cooling chamber.In this paper,the gas and liquid phase distribution and turbulence characteristics in the annulus space of the washing and cooling chamber are studied in a scrubbing cooling chamber cold model apparatus which is geometrically similar to the industrial gasifier.And the CMC and Sodium Oleate were used to simulate the change of liquid phase properties,the main conclusions are as follows:(1)The bubble diameter and gas holdup distribution in annulus space were studied by means of a two-head conductivity probe measurement system.The critical diameter of bubbles in the rising,transition and falling regions is 5 mm,4 mm and 2 mm respectively.With the increase of viscosity,the gas holdup increases first and then decrease.And the viscosity at inflection point is 4.31 mPa·s.The decrease of surface tension makes the local gas holdup decrease gradually.The gas holdup below the bubbler(h/D=0.19-0.61)gradually decreases along the radial position,while the gas holdup above the bubbler(h/D=1.03)presents a parabolic distribution.And the gas holdup increases significantly with the increase of the apparent gas velocity.A local gas holdup correlation formula suitable for high apparent gas velocity is established by using optimal fitting.(2)The liquid velocity distribution in the axial and tangential directions of different tower heights was studied by using the pitot tube and differential pressure transmitter velocity measuring device.The velocity distribution of the liquid phase:the liquid phase gradually decreases along the radial direction at h/D=0.19-0.61,and the velocity turns at r/R=0.7 and r/R＝0.6,respectively.At h/D=1.03,the velocity presents a parabolic distribution;The tangential velocity is small(-0.15-0.05 m/s)and decreases with the increase of axial height.In the rising region,the liquid velocity increases slightly with the increase of viscosity and surface tension.The correlation formula of UZ/UC model suitable for high tower diameter and high gas velocity is established by using the normalized analysis.(3)The characteristic parameters of turbulence were analyzed by Reynolds decomposition and spectrum analysis.Turbulent shear stress and axial normal stress are the largest at the velocity turning point,which are 0.045 m2/s2 and 0.06 m2/s2,respectively.Here the tangential normal stress is about 0.5 times of that in the axial direction.The critical gas velocity of slug flow and churn-flow is 0.22 m/s.With the increase of the apparent gas velocity,the turbulent axial normal stress first decreases and then increases,while the tangential normal stress gradually increases,and the minimum axial normal stress is 0.06 m2/s2.The transition frequency is consistent with the decomposition velocity of eddy current scale and increases with the increase of the apparent gas velocity.