共查询到19条相似文献,搜索用时 156 毫秒
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根据液相在波纹规整填料片上呈现渗流、膜状流等不同的流动方式,选择5种不同的波纹规整填料对其流体力学和传质性能进行研究,以探究液相在波纹片上的流动方式对波纹规整填料性能的影响.研究结果表明,液相呈渗流流动的泡沫碳化硅波纹规整填料(SCFP型)有利于液体横向扩散和液膜均匀分布,当液相喷淋密度和气相F因子均较小时,其压降最低,传质效率最高;液相主要呈渗流流动、兼有膜状流动的双层错孔丝网填料(DMⅢ型)有利于波纹片两侧液体交换,强化液体在流动过程中的扰动,其压降及传质性能略逊于SCFP型填料;液相主要呈膜状流动的BX型、DMⅠ型及DMⅡ型填料波纹片表面液膜较厚,横向扩散能力差,其传质效率低于SCFP型和DMⅢ型填料.研究揭示了依靠渗流作用的波纹规整填料具有较好的应用性能,为波纹规整填料的进一步发展开拓了新思路. 相似文献
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为了研究规整填料局部特征单元内流体的流动状况和传质效果,采用计算流体力学的方法对JKB-250Y交叉波纹填料以及增加隔板后的JKB-250Y交叉波纹填料进行了模拟计算比较。结果表明,加入隔板后有效改善了传质的局部均匀性,并且消除了两股气体交叉流动带来的阻力,降低了通道的单位压降。增加隔板后的交叉波纹填料压降比传统交叉波纹填料压降降低20%~50%,增加隔板后的交叉波纹填料传质系数比传统交叉波纹填料传质系数提高约20%,可见提高传质分布的局部均匀性是提高传质效率并且降低阻力的较为有效途径之一。 相似文献
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气液两相不均匀流动是造成填料塔传质效率下降的主要原因之一.采用计算流体力学方法,定量分析规整填料内气液两相流动对传质效率影响的研究尚未见文献报道.从Navier-Stokes方程出发,首先建立了考虑气液之间相互作用的CFD计算模型,定量描述了填料片内的气相流场分布.在此基础上,结合文献中提出的液相结点分布模型及一些经典的传质理论,初步提出了适用于定量计算金属板波纹填料传质效率的耦合型算法,并对规整填料内的传质效率进行了计算,模型结果与实验值吻合较好.为规整填料传质效率的定量研究提供了新的方法和思路. 相似文献
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通过采用配备微距镜头的高速摄像仪记录单波纹片上的液体流动行为,发现了泡沫碳化硅波纹规整填料内同时存在液膜流动和准壁流两种液体流动模式。同时测定了组合波纹片之间的液体传递量,并将泡沫碳化硅波纹规整填料与金属丝网波纹填料和金属板波纹规整填料的测试结果进行比较,结果表明泡沫碳化硅波纹规整填料的单波纹片上的液体扩散程度较大,组合波纹片之间的液体传递量高于金属丝网波纹填料和金属板波纹规整填料。研究结果揭示了泡沫碳化硅波纹规整填料具有高效传质特性的根本原因在于其独特的三维空间网孔结构增强了液体在单波纹片上的横向扩散能力和在组合波纹片之间的径向传递能力,为新型高效规整填料的机理研究和进一步开发开拓了思路。 相似文献
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综述了规整填料传质性能的计算方法和模型,并对这些模型的理论基础和适用条件进行了分析和比较。归纳了近年来对于传统规整填料传质模型的修正和扩展,并对影响传质性能的有效比表面积的经验关联式进行了讨论,指出了规整填料传质性能研究方面进一步的探索方向和应改进的若干问题。 相似文献
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用简化三维混合池模型对Gorak所做精馏实验作了实例计算。模型的计算结果与Gorak实验数据符合良好,以简化三维混合池模型为工具,用数值计算的方法研究了规整填料塔中液体流动分布和混合对精馏过程的影响。结果表明:液相轴向返混对精馏有着显著的不利影响;当液体流动分布为严重壁流分布(严重沟流分布)时,必须用三维模型描述才不会产生较大偏差;横向混合系数的增大有利于填料塔分离效率的提高,但不能完全抵消液相严重不均匀分布对精馏过程的不利影响。 相似文献
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将填料单元处理成立体节点网,根据节点网内网线液流和节点液流各自的运动方式建立了填料单元的液体分布模型.通过将填料与塔壁间的液体交换规范成填料节点网与塔壁节点网间的液量传递建立了填料单元对应塔壁区的流体分布模型.提出了规整填料塔液体分布问题的边界条件.2个描述填料单元及其对应塔壁区液体分布的数学模型与2类边界条件共同构成了波纹板规整填料塔的液体分布模型.采用单纯形法对3个模型参数进行了估计.模型计算结果与实验数据一致,表明模型能合理地描述波纹板规整填料塔的液体分布性能. 相似文献
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规整填料内单相流的LDV实验研究 总被引:1,自引:0,他引:1
To date, many models have been developed to calculate the flow field in the structured packing by the computational fluid dynamics (CFD) technique, but little experimental work has been carried out to serve the vali-dation of flow simulation. In this work, the velocity profiles of single-phase flow in structured packing are measured at the Reynolds numbers of 20.0, 55.7 and 520.1, using the laser Doppler velocimetry (LDV). The time-averaged and instantaneous velocities of three components are obtained simultaneously. The CFD simulation is also carried out to numerically predict the velocity distribution within the structured packing. Comparison shows that the flow pattern, velocity distribution and turbulent kinetic energy (for turbulent flow) on the horizontal plane predicted by CFD simulation are in good agreement with the LDV measured data. The values of the x-and z-velocity components are quantitatively well predicted over the plane in the center of the packing, but the predicted y-component is sig-nificantly smaller than the experimental data. It can be concluded that experimental measurement is important for further improvement of CFD model. 相似文献
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An experimental investigation was carried out to examine the fluid dynamic and mass transfer behavior of structured packing, with the liquid and gas phase flowing co‐currently downwards in the column. Liquid to packing mass transfer coefficients for three positions within the pack were measured by an electrochemical method, varying both the liquid and gas loads as well as the physical properties of the liquid phase. Due to the high void fraction of structured packing, much higher liquid flow rates can be used than in traditional particle trickle‐beds. It was found that in the range studied, the gas superficial velocity has no effect on the mass transfer rate and thus, a general mass transfer correlation in terms of liquid Reynolds number only, was developed. Wetted areas and the radial distribution of liquid through the packing element were determined by a colorimetric method. Within the range of liquid flow rates investigated, complete wetting is not achieved, even with the low viscosity solutions. The measured ratios of hydraulic to geometric area, agree reasonably well with values predicted by existing relationships. 相似文献
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Detailed investigation of flow behavior in structured packing distillation columns is of great importance in accurate prediction of process efficiency and development of more efficient and optimal equipment internals. In this study, a three-dimensional two-phase flow model based on VOF method for simulating the hydrodynamics and mass-transfer behavior in a typical representative unit of the structured packing is developed. In the proposed model, the model is used for the closure of turbulent mass transfer equation. By solving the proposed model, the velocity distribution, phase fraction profile and concentration field are obtained. Using these data, the total liquid holdup, the wetted area and the separation efficiency [height equivalent to a theoretical plate (HETP)] are estimated. For testing the model validation, the simulated HETPs are compared with our previous experimental data obtained in a 150 mm-diameter column containing Mellapak 350Y operating at the pressures of 0.6-1.8 MPa. The compari-son shows that they are in satisfactory agreement, with an average absolute deviation (AAD) of 25.4%. 相似文献
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In order to model and optimise industrial gas/liquid contactors such as those used for distillation or for post-combustion capture of CO2, liquid hold-up and liquid distribution have been measured for two modern high capacity packings, a structured packing and a random packing. A gamma-ray tomographic system has been used to obtain liquid flow maps over a cross section of a 400 mm internal diameter column from which liquid hold-up values can be deduced. It is observed that the liquid flow is homogeneously distributed for both packings, the structured packing giving better results. Correlations are proposed to estimate the liquid hold-up, the effect of the liquid flowrate and the liquid viscosity being taken into account. A non-negligible static liquid hold-up is considered for the structured packing, which can be explained by the texture on the packing walls. As long as there is a little effect of the counter current gas, then below the loading point, results can be extrapolated to larger columns. 相似文献
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Radial liquid distribution was measured experimentally for cocurrent, two-phase downflow in packed beds. The effects of bed length, water and air flow rates, and type of packing were determined. The experimental data were obtained in the gas-continuous, transition and pulsing trickling-flow regimes. For all finite air rates, the liquid velocity profiles were approximately flat with the maximum average velocity occurring at the center of the packed column. Increasing the air rate increased the center liquid velocity. The gas rate effect was more pronounced in shorter beds. At higher gas rates the liquid rate had less effect on the radial liquid distribution than at lower gas rates. Operation at higher liquid rates resulted in a flatter radial liquid veilocity profile. It was observed that the bed of pellets operated at high liquid rate and low gas rate was unstable. Increasing the bed height increased the stability of the system and a better liquid distribution was obtained. The effects of water flow rate, bed length, and packing type on the shape of the liquid velocity profiles were minor. 相似文献