Investigation Into The Absorption In A Cyclone Absorber Of Spraying Liquid From Side Wall

The gas absorption has wider application in chemical production. Because of complex structure and high cost of traditional gas-liquid absorption equipment, while RPB (Rotating Packed Bed) as late model equipment for absorption is restricted for its high energy consumption and reliability stability of motion, reducing construction investment and developing easy and reliable equipment for gas-liquid absorption become more and more important. However, for simple structure,maintenance-friendly and the low cost of investment, cyclone has been widely researched and applied in centrifugal action separation field. Actually, there is hydromechanics environment in which transfer process can be strengthened.Simulation study for the single phase and multiphase flow in cyclone absorber was set forth by the Computational Fluid Dynamics(CFD)software. Through indirect methods of verification, the suitable scheme was received for CFD in the cyclone absorber in this present. The order of magnitude of tangential speed is larger than those of radial and axial speed, and there is the grade of velocity in swirling flow field from the result of CFD, in line with the description of related literature. It was verdicted that there be relative speed of radial of two phases which can strengthen the contact of two phases and is in favor of mass transfer, with the increased handling capacity,tangential relative speed and axial relative speed which are comparatively small. Besides, Because of entering the liquid on side wall, the axial relative velocity is augmented in the cyclone absorber manufactured in this work from the result of CFD, whereas it is needed that looking for a more sutitable situation for nozzle from the distributing of volume fraction of two phases.Through the dynamics analysis of dispersed phase in swirling flow field, the radial motion equation of particles and relative motion equations of two phases have been derived on the basis of the analysis of force. From the dispersed phase radial motion equation, the distribution of the radial velocity of dispersed phase particles to radius in cyclone and its analytic solution were obtained, furthermore , as a result, the radial motion time of particles t r in swirling flow field gained. Moreover, the relative speed of radial of two phases is consistent with that of CFD in this present, while tangential relative speed and axial relative speed have exponential decay with time according to relative motion equations of two phases. Under the condition of no slip between two phases in axial movement, the axial motion time of dispersed phase t zwas derived, and the trajectory equation of particles was established in relate to the distribution of the radial velocity of dispersed phase particles to radius, which could be used to count work efficiency of cyclone and be used for design of cyclone and its development.From the application of dimensional analysis method, stress in swirling flow field was analyzed, leading to the investigation into distortion and breakage of particles. According to the results of dimensional analysis, the conclusion is that Reynolds stress is larger than viscosity stress in turbulent flow, and the multiple is the Reynolds number, which induces into breakage of particles. In other regions,what can happen to the dispersed phase pellet mainly is distortion and coalescence, which plays the leading role is in cyclone viscosity sheering force, in which the most important part are tangential and radial viscosity sheering force. Based on this, critical condition for the breakage of particles under viscosity sheering force and turbulent energy was deuced. Through the relationship between Weber number and the relative speed, situation of distortion or breakage of dispersed phase particles in region-specific could be comprehended under the specific handling capacity.On CFD and theoretical analysis foundation, the peculiarities of mass transfer in cyclone absorber were set forth. The gas-liquid absorption process was intensified not only by the relative speed in cyclone, but also the grade of velocity in swirling flow field, owing to which, turbulent diffuse coefficient and dispersion coefficient that is much larger than diffuse coefficient in turbulent flow come into being in cyclone, intensifying the swirling flow field to aggrandize mass transfer enormously.A mathematic model of gas-liquid absorption and mass transfer with chemical reaction in a cyclone absorber has been established according to different dynamical characteristics of the dispersed phases in swirling flow field based on the species mass-conversation equations in this thesis, which is consistent with the Danckwerts' Surface Renewal Theory. Not only considering the diffusive term and source term, but also the transient and convective term, this model could explain the reaction process in swirling flow field much more exactly. But because the model's computation needs to determine some specific physical quantities, it is restricted for application.According to the theory of mass transfer for gas-liquid and turbulence, established based on vortex has been suitable for gas-liquid absorption in cyclone absorber mass transfer model. The model compared to other models, parameters mainly were related to some measurable and controlled parameters about operation,nature and structure in macro aspects, so its computation is simple and its significance is clear. From the process of making sure the relevant parameters, the model can also be applied to the general freedom of the interface of gas-liquid mass transfer.By the mass transfer coefficient model, the correlation of diffusion time t D was available. On the base of the demand for t D << tr<