气体分布器孔径对泡沫分离过程影响的研究

气体分布器孔径是控制气泡大小的重要因素,也是制约泡沫分离效率的重要因素。开发了一种高分子膜材料用于泡沫分离气体分布器,以十二烷基硫酸钠(SDS)为体系,研究了气体分布器孔径对表面过剩,质量流率,消泡液的表观液体流速,泡沫排液速率以及泡沫分离效率的影响。结果表明高分子膜材料适合用于泡沫分离塔的气体分布器。气体分布器孔径对表面过剩影响不明显,而对质量流率有显著影响。当平均孔径从23μm增大到165μm时,消泡液的表观液体流速降低89%,泡沫排液速率降低93%;SDS富集比从1.14增大到2,提高75%,回收率下降80%。由导出的富集比和回收率计算式得出的计算值与实验值吻合很好。     

化学工程2004年(第32卷)第1—6期(总第191—196期)总目次

蒸馏、吸收、萃取、干燥、吸附等过程及设备　　　　　　　　　　　　　　　　　　期　页新型立体传质塔板罩内压力分布和气液　提升机理的研究 11蒽醌法过氧化氢合成中喷射萃取过程研　究 16电场强化臭氧向水中传质的试验研究 15 2碳三催化精馏加氢模拟计算 15 6三烷基氧膦与二 (2 乙基己基 )磷酸协　萃对氨基苯酚的研究和应用 2 1盐效分离作用理论预测 2 6吸附法脱除天然气中少量丙烷和丁烷的　研究 2 10表面张力对传质过程的影响 2 14垂直管外降膜的切向旋转沟槽型液体分　布器特性研究 2 2 9CO2 跨临界循环特性对热泵干燥系统的　影响…     

CFD优化双切向环流式气体分布器设计

双切向环流式气体分布器是一种应用较为广泛的气体分布器,现阶段多靠经验进行设计,缺少必要的理论支持.本文应用计算流体力学(computational fluid dynamics,简称CFD)所建立的双切向环流式气体分布器内三维瞬态气液两相流模型,考察了折流板数量、导流板径向夹角等因素对大直径(7.4m)分布器综合性能的影响,优化了双切向环流式气体分布器设计.     

填料塔液体分布器的研究进展

填料塔作为化工单元操作过程中重要的汽液传质设备,因具有传质效率高、整塔压降低、能耗低等优点,已经成为精馏操作中的关键设备。液体分布器是填料塔中重要的塔内件,其结构形式直接关系到液相物料在塔内的分布情况,从而影响填料塔的分离效果。本文系统介绍了液体分布器的发展现状,从自然流分布、径向分布系数等方面详细总结了分布质量对填料塔分离效率的影响;深入分析了国内外关于各种结构类型的液体分布器的理论研究以及设计优化过程;并总结了不同液体分布器分布质量评价方法的适用场景。文章最后对液体分布器的发展进行了展望,为液体分布器的设计与优化提供了思路。     

槽式液体分布器分布性能的研究

文中以大型的工业用槽式液体分布器为研究对象,研究方法有理论计算、实验和流体模拟软件模拟。研究发现:传统的槽式液体分布器其分布孔的设计存在偏差,分布器分布管出口流量、一级槽自身液面稳定能力以及液面梯度都对分布器的分布性能有影响。文中提出了一种新型槽式液体分布器,有利于提高填料塔的效率。     

结构型槽盘式液体分布器性能研究

针对槽式液体收集再分布装置存在的占塔空间大的缺点,设计制造了一种结构型槽盘式液体分布器,使单套液体收集再分布装置总高降低18.8%,为降低全塔阻力及塔高提供保障。在此基础上,利用FLUENT软件模拟气相通过槽式液体收集再分布装置、传统槽盘式和结构型槽盘式分布器的阻力损失,同时搭建了液体分布器分布性能测试平台,对该结构型分布器进行分布性能测试。结果表明:结构型分布器较传统分布器阻力减小很多,说明其设计的合理性。对该结构型液体分布器的液体分布性能测试结果进行分析评价,表明该分布器分布性能为优,确保塔内液体实现良好的液体分布,且在工业应用中初见成效。     

液体分布器研究进展及新技术

液体分布器是空分膜式主冷凝蒸发器中的关键设备,液体均匀分布是换热器性能的保证。本文综述了目前竖直管降膜蒸发器和空分膜式主冷用液体分布器的研究现状,发现大多液体分布器结构存在无法有效排出蒸汽的不足。在已有液体分布器结构的基础上,提出了一种可以集中排出蒸汽的液体分布器结构形式,上述设计为空分膜式主冷凝蒸发器用液体分布器设计提供了重要参考。     

填料塔液体分布器的设计(续一)──第二讲 排管式液体分布器的设计

从分布器设计的理论基础、性能准则、常规方法和计算机程序这几个方面探讨了填料塔排管式液体分布器的设计问题,并给出了一个工业设计实例。     

气体分布器的数值模拟与改进设计研究

针时双切向环流式和双列叶片式两种气体分布器,利用计算流体动力学数值方法模拟研究其流场规律,比较两种分布器的多种性能。在此基础上,提出对双列叶片式气体分布器进行改进设计;并模拟结果表明,改进后的气体分布器在均匀度方面有进一步提高。     

填料塔旋转液体分布器的研究

本文介绍了一种填料塔旋转液体分布器。推导出了最佳开孔位置和转速的计算式。得出了转速、液体流量、开孔角度、气体流量对分布的影响。并给出了计算实例。     

滴流床反应器气液分布器CFD模拟

以溢流型滴流床反应器进口气液分布器为研究对象,利用计算流体力学方法(CFD)进行分布器的分析及开发。研究结果显示,对于大气液比、低喷淋密度的反应系统,在相同液层高度条件下,管内的气相流速显著影响过孔液速,气速较大时,液体过孔流速也相对较大。同时由于液量偏少,液体容易形成中心汇流,且难以向溢流方向的垂直方向扩散。采用双层碎流结构后能使液体在整个截面分布更均匀。     

乙炔中和工序的改造

针对乙炔中和工序中和塔处理能力不足进行了改造,包括改造液体分布器,增大中和塔塔径和塔高,对碱液循环泵重新选型等;改造后雾沫央带现象减轻,总管积液量减少,积液pH值降低,有效地降低了生产成本。     

Experimental studies of liquid flow maldistribution in a random packed column

Liquid flow distribution has been a major concern when scaling up random packed columns. This study concerns the measurements of liquid flow distribution in a large scale column packed with 25.4 mm stainless steel Pall rings. The liquid flow distribution was studied with packed bed height from 0.9 to 3.5 m, liquid flow rate from 2.91 to 6.66 kg/m²·s, and gas flow rate from 0 to 3.0 kg/m²·s. In addition, three systems, water/air, aqueous detergent solution/air and Isopar/air, were used to study the effect of liquid physical properties on liquid flow distribution, and two different liquid distributors were employed to test the effect of liquid distributor design. It was found that liquid flow distribution was strongly influenced by liquid distributor design, packed bed height, gas flow rate and liquid viscosity, slightly influenced by liquid flow rate, but not by liquid surface tension.     

外环状弹性壁布膜器及超薄降膜厚度

研发了竖直管外环状弹性壁降膜分布器,可以产生微米量级厚度均匀的超薄降膜流动。由弹性薄壁轴对称变形协调性决定,该布膜器具有均匀性和稳定性内在机理。理论分析导出了初始膜厚及布膜流量与布膜器内液柱高度的线性关系,并通过布膜器操作参数及降膜流量等实验数据进行了验证。实验结果表明,该布膜器对降膜管壁的润湿性能已经达到由固液界面性质决定的最小润湿流率。     

Simulation of Orifice Flow Influenced by Lateral Flow in a Trough‐Type Liquid Distributor

A computational fluid dynamics (CFD) simulation is performed to investigate the influence of lateral flow on the orifice flow in a trough‐type liquid distributor. The discharge coefficients from the simulation are in good agreement with the experimental values, indicating that the CFD simulation is accurate in describing the outflow through orifices. The lateral flow near an orifice can change the velocity and pressure distributions of flow regions in front of this orifice, causing a decrease in the discharge coefficient. This phenomenon is supported by the theory of flow past a blunt body. An important implication derived from this finding is that the influence of lateral flow should be minimized in the design of a trough‐type liquid distributor, because the decrease in the discharge coefficient leads to non‐uniform outflow. The structure of a trough‐type liquid distributor is optimized to improve the liquid distribution performance by reducing the influence of lateral flow.     

A new streamlined bubble-cap distributor for high gas–liquid ratio and the liquid distribution mechanisms

The bubble-cap distributor is the most commonly used and critical internal for trickle bed reactors but holds the inherited disadvantage of liquid central aggregation when operating at a high gas–liquid ratio. A new bubble-cap distributor with a streamlined downcomer was developed in this paper to counter back the liquid aggregation and improve its comprehensive performance. The effect of the streamline parameters of the new distributor on liquid distribution was systematically explored by the coupled Euler–Euler-population balance equation (PBE) model. Compared with the classical and polyline converging–diverging structures, the results showed that the streamlined downcomer was a key to generating radial velocity of two-phase flow and reducing the liquid central aggregation for the bubble-cap distributor. The mechanism of well-distribution was explored for the new distributor. Lower converging and diverging angles enhance the distribution performance. A downcomer with a small converging angle and a 30° diverging angle was recommended for dispersing the central aggregated liquid column and acquiring the high distribution uniformity and spray covering circle. These data would be helpful to the optimal design and scale-up of the bubble-cap distributor in further industrial applications.     

A computational fluid dynamics-based method to investigate and optimize novel liquid distributor

Liquid distributors have an important influence on packed towers' hydrodynamics and mass transfer performances. This work has designed a narrow-trough liquid distributor with stepped baffle plates to regulate liquid flow. The liquid mainstream is diverted layer by stepped baffles to realize the uniform distribution of liquid. The relationship between liquid flow and the baffle plates arrangement is studied by computational fluid dynamics (CFD) simulation. Furthermore, we put forward a CFD-based structural optimization scheme to arrange baffle plates in an arc shape, which leads to a uniform and stable flow of each distribution orifice in the range of liquid spray density of 5–120 m³·(m²·h)⁻¹. The simulation results agree with experiments, which proved that the novel liquid distributor has excellent performance. Compared with the traditional trough liquid distributor, the novel liquid distributor can provide more liquid drip points, more gas-phase channels, higher operating flexibility, and take up less space.     

整体式床层中液体分布与气-液传质的关系

With a particular focus on the connection between liquid flow distribution and gas-liquid mass transfer in monolithic beds in the Taylor flow regime, hydrodynamic and gas-liquid mass transfer experiments were carried out in a column with a monolithic bed of cell density of 50 cpsi with two different distributors (nozzle and packed bed distributors). Liquid saturation in individual channels was measured by using self-made micro-conductivity probes. A mal-distribution factor was used to evaluate uniform degree of phase distribution in monoliths. Overall bed pressure drop and mass transfer coefficients were measured. For liquid flow distribution and gas-liquid mass transfer, it is found that the superficial liquid velocity is a crucial factor and the packed bed distributor is better than the nozzle distributor. A semi-theoretical analysis using single channel models shows that the packed bed distributor always yields shorter and uniformly distributed liquid slugs compared to the nozzle distributor, which in turn ensures a better mass transfer performance. A bed scale mass transfer model is proposed by employing the single channel models in individual channels and incorporating effects of non-uniform liquid distribution along the bed cross-section. The model predicts the overall gas-liquid mass transfer coefficient with a relative error within ±30%.     

Liquid Holdup in a Pilot‐Scale Turbulent Contact Absorber – An Experimental and Comparative Study

Liquid holdup in a turbulent contact absorber was determined experimentally. Experiments were performed in a 44.7 cm diameter Perspex column. Hollow spherical high‐density polyethylene balls were used as packing. The effect of liquid and gas velocities, static bed height, diameter and density of packing on liquid holdup was investigated for the range of gas velocities greater than minimum fluidization velocities. Also, the effect of gas and liquid distributors on liquid holdup was studied. Correlations for liquid holdup were developed and compared with those in the literature. It was observed that liquid holdup increased with the increase in liquid velocity, packing density, and the decrease in static bed height. Liquid holdup also increased with gas velocity when the gas distributor section was included, while no effect was observed for the bed. Lack of information on the contribution of liquid and gas distributors seems to be the logical explanation for the wide variation in data reported in the literature.     

环形分布器内变质量流动的CFD模拟研究

环形分布器是实现导热介质在列管式固定床反应器壳程均匀流动的关键部件,文中采用计算流体力学方法(CFD)对环形分布器内的变质量流动进行了模拟研究。首先计算了环形通道内的速度和静压力分布,在此基础上研究了穿孔阻力系数随开孔几何结构以及入口流体流速的变化规律。模拟结果表明:环形通道内存在较明显的速度梯度和压力梯度;随着流体不断分流,在流道内的流动速度不断减小,静压力逐渐增大。因此,需要沿流动方向将开孔直径逐渐减小,以增大穿孔阻力,从而实现流体的均布。对穿孔阻力系数变化规律的研究结果表明:穿孔阻力系数ξ与出口和主流道的流速比ui/u、厚径比δ/di和入口雷诺数Re0有关。在模拟范围内,ξ先随ui/u的增大而减小,到达一个临界值后,ξ不再随ui/u的增大而变化;δ/di对ξ影响不太明显;当Re0属于湍流范围时,ξ随Re0的变化不太明显,但是总体随Re0的增大而减小。