Study On Flow Characteristic Of The Liquor Distributor On The Vertical Tube Falling-film Evaporator

The Liquor Distributor is one of the key structural in the Vertical Tube Falling-film Evaporator,may directly affect the distribution effect,This thesis centres on the Liquor Distributor 's structural and flow field characteristics by numerical simulation and experimental research.The classification and application characteristics of commonly used are analyzed.At present,there are many researches on the Liquor Distributor in China,and introduced the application of different forms of the Liquor Distributor devices.The research results of flow characteristics of liquid film in vertical tube descending film are enumerated.The general method of CFD simulation of falling film evaporator is discussed.same speed import and export pressure(an atmospheric pressure)conditions to fluid model is simplified,based on the hexahedron grid structure of 3d mesh model,choose standard turbulence model,set up the water surface tension 0.063 n/m and two-phase(water-air)flow model used to simulate the numerical simulation.The flow state of fluid in the device is numerically simulated by controlling the plug-in,the height of the cloth and the flow.The simulation results show that the device with a taper plug can greatly improve the uniformity of the liquid arrangement and improve the stability of the film.The height of the perforated plate has less effect on uniform membrane.The non-plug-in model has poor effect on the cloth membrane of the simulated flow.The conical plug-in model can realize the uniform membrane when the flow rate is greater than 350ml/s,which is best when the flow is 620ml/s.As the flow increases,the liquid level above the tube board in the cloth liquid device with the plug-in is higher,and the liquid film will be more uniform.The velocity of flow and liquid film is linear.The Falling-film experiment device was developed.Experiment platform based on falling film,compared with uniform membrane of plug-in Liquor Distributor device and non-plug-in Liquor Distributor device,statistics of the conical plug-in unit based on the distribution of the flow under the condition of the Different total flow.Obtain therelationship between each tube flow change curve,calculated the flow distribution uniformity coefficient of variation.The results show that the two kinds of devices can allow the liquid film on the wall surface,but the stability of the liquid film without the plug-in device is poor,and the membrane effect is relatively good when the small flow.The conical plug-in device can form good uniform membrane in the large flow range.At the same time,the simulation results are well validated.