两级组合式除雾器的分离性能分析

为研究两级组合式除雾器的分离性能，对两级旋流式、组合式、两级折流式3种除雾器进行性能分析。通过数值模拟方法分析除雾器内部流场差异，通过搭建实验平台，利用高速摄影技术并结合除雾器流场分布分析液滴在除雾器内部运动行为，进而从压降损失、分离效率、出口液滴粒径等方面开展除雾器分离性能的实验研究。结果表明：液滴在折流板内主要靠撞击叶片累积形成液膜而被捕集，在旋流板内沿叶片边缘滑动，以接近叶片倾角角度向壁面运动形成液膜被捕集；随入口截面速度增加，3种除雾器压降均逐渐增大，差值不断增加，两级旋流式除雾器压降最高；当入口截面速度低于5.7m/s时，两级旋流式、组合式除雾器分离效率均接近100%，同时组合式除雾器出口液滴中位粒径始终低于入口液滴中位粒径，并小于其余两种形式除雾器，对小粒径液滴分离能力显著；当液相流量从6.2m³/h逐步增加至13.7m³/h，3种形式的除雾器分离效率随液相流量增加呈下降趋势，其中两级旋流式除雾器在高气速、高液相流量下适应性最强，同时3种除雾器出口液滴中位粒径总体呈现下降趋势，其中组合式除雾器出口液滴中位粒径仍居于最低水平。     

氨油分离器内高效气液分离元件分离性能的数值研究

采用FLUENT软件对氨油分离器中波纹板除雾器和丝网除雾器内的气液两相流场进行数值模拟计算,考察除雾器的结构参数与操作参数对进出口压降和分离效率的影响规律。结果表明:波纹板除雾器的压降随入口气速的增大而增大,随叶片转折角度的增大而减小,分离效率随液滴直径的增大而增大,随入口气速的增大而增大,随叶片转折角度的增大而减小;丝网除雾器的进出口压降随入口气速的增大而增大,分离效率随入口气速的增大而增加,随入口液滴直径的增大而增加;波纹板和丝网组合在一起的整体分离效率提高,且随着液滴直径的增大,整体分离效率上升很快。     

折流板除雾器分离特性的数值模拟研究

折流板除雾器是一种工业中广泛使用的气液分离设备,对折流板除雾器的研究目前主要集中在提高除雾效率、降低进出口压降、防止堵塞等方面。除雾效率和压降是除雾器的两个最重要性能,因而成为研究的重点。目前对除雾器的研究方法主要为实验和数值模拟,实验方法因其投入高、周期长、过程繁琐而逐渐被数值模拟方法所取代。     

折线型与流线型除雾器性能的数值模拟与分析

采用Fluent软件对折流板除雾器内气液两相流动进行数值模拟,分析了不同除雾器型式、叶片转折角对除雾器的分离效率和压降的影响。计算结果表明：Fluent软件可以成功地处理两相流动问题,为除雾器优化设计提供参考依据。     

组合式纤维除雾器的工业试验

南化公司研究院硫酸试验车间和马鞍山硫酸厂进行了组合式纤维除雾器的工业试验,试验中对除雾器的气速、压降、效率进行了测定。工业试验表明,在效率相同的情况下,CTP-M型、CT-M型组合式纤维除雾器的压降比早期开发的CTP型、CT-1型纤维除雾器降低20～40％。     

直流降膜式旋风除雾器的试验研究

本研究开发了一种新型的旋风除雾器－－直流降膜式旋风除雾器。并实验测定了其压降、除雾效果及液膜在器壁上的成膜情况，提出了压降随气液流量的关联式，除雾效果可达到生产要求，找到了液膜在器壁上成膜均匀的操作条件。     

叶片式入口分离器气液流动及分离性能数值模拟

叶片式分离器是一种较新颖的气液两相流设备的入口分离及布气装置。为了给设计提供指导,本文采用离散相模型对其中的气液两相流动过程进行模拟,并通过分离效率测试对计算模型进行了验证;在此基础上研究了气速、液滴粒径、叶片倾角及流道入口宽度对分离性能的影响。结果表明:叶片式分离器具有良好的气液分离性能,对于粒径大于50μm的液滴分离效率能够达到85%以上,增大气速和液滴粒径有利于提高叶片式入口装置的分离效率;综合考虑分离效率和压降,叶片倾角宜设置为5～8°;在现有流道宽度设计建议的范围内,减小流道宽度可显著提高小液滴分离效率,但阻力也将增加。     

基于ODA/PDMS粗糙结构的仿生光滑液体灌注膜

相较于表面易损伤、压力稳定性差的超疏水表面，具备特殊浸润性的光滑液体灌注表面(SLIPS)在油水分离膜材料的开发上有良好的应用前景。本文使用聚丙烯(PP)和聚酯(PET)纤维膜作为基底，通过一步浸涂法在基底上构造了ODA/PDMS疏水粗糙结构，在其上灌注润滑油，制备了一种具备SLIPS的仿生光滑液体灌注膜(SLIM-ODA/PDMS)。这种光滑液体灌注膜具有良好的疏液性和较好的重力下油包水乳液分离能力，分离率在99.8%以上，这为新型油水分离材料的开发提供了思路。     

基于响应面法的折流板除雾器分离性能优化

用响应面分析法分析不同排液结构对新式异型折流板除雾器气液分离性能的影响,并对排液结构参数进行优化设计. 通过单因素实验对比筛选对除雾器性能具有显著影响的关键参数,用中心复合设计实验建立响应面多元回归模型,分析影响除雾器性能系数的参数间交互作用,得出最优参数. 结果表明,影响除雾器性能参数的最优取值为分离气速2.6 m/s、排液钩高度7.3 mm、前置排液槽和后置排液槽宽度分别为3.1和2.3 mm. 优化的折流板除雾器性能系数计算值为2.073,实验值为1.875,优化结果较可靠.     

基于光固化微压印制备仿生荷叶疏水薄膜的研究

采用光固化微压印制备仿生疏水薄膜的工艺方法,制备了具有荷叶表面微结构的聚二甲基硅氧烷(PDMS)软模具,在此基础上,制备了仿生疏水薄膜,探究了紫外光辐照时间、辐照强度等对疏水薄膜水接触角的影响。结果表明,PDMS模具能够较好地复印荷叶表面的微结构,增加辐照时间和辐照强度改变压印压力可以有效提高疏水薄膜的疏水性,当辐照强度为1 000 mW/cm~2、压印压力为0.2 MPa、辐照时间为20 s时,制备的仿生疏水薄膜的表面接触角达到153.5°。     

A correlation giving improved description of the capacity and efficiency of vane-type gas–liquid separators

Vane-type demisters are attractive droplet separators because they combine robustness and sufficient separation efficiency with a low-pressure drop, a high capacity and some fouling resistance. Experience shows that their optimal operation is close to the maximum capacity point and even that at this point the separation efficiency is better at higher pressures. This article proposes a generalized expression this point, as a function of gas and liquid flow and properties, drawing on knowledge about other, related, unit operations, namely cyclone separators and distillation towers. The generalized expression relates the dimensionless velocity with the Archimedes number and a flow parameter. The expression builds on earlier work on a criterion for the inception of droplet entrainment in two-phase film flow, pioneered by Ishii and Grolmes, and is supported by considerable experimental work published over the last 50 years.     

除雾器内雾滴运动特性与除雾效率

利用流体动力学计算方法对湿法脱硫折流板除雾器内气液两相流动进行数值模拟.分析了除雾器叶片间距、板型及流速对不同粒径雾滴的分级除雾效率和总除雾效率的影响,获得了不同粒径雾滴的运动和捕集规律.研究结果表明,粒径小于10 μm的雾滴去除效率随流速增加呈现不规律的波动,随板间距增加而下降的趋势不明显,不受叶片形状变化影响;粒径大于16.3 μm的雾滴去除效率随流速增加而增大,随板间距增加而显著下降;在板间距为38 mm时,梯形板除雾效率大于三角形板,在板间距较小的情况下两种板型的性能相差不大;流速小于3 m·s^-1时,粒径小于20 μm的雾滴的去除对气流均匀性要求较高,气流扰动增加利于小雾滴的碰撞聚并;流速高于3 m·s^-1时,气流扰动增强增加了小雾滴运动的随机性,不利于小雾滴的碰撞聚并.     

Optimal design of drainage channel geometry parameters in vane demister liquid–gas separators

Vane liquid–gas demisters are widely used as one of the most efficient separators. To achieve higher liquid disposal and to avoid flooding, vanes are enhanced with drainage channels. In this research, the effects of drainage channel geometry parameters on the droplet removal efficiency have been investigated applying CFD techniques. The observed parameters are channel angle, channel height and channel length. The gas phase flow field was determined by the Eulerian method and the droplet flow field and trajectories were computed applying the Lagrangian method. The turbulent dispersion of the droplets was modeled using the discrete random walk (DRW) approach. The CFD simulation results indicate that by applying DRW model, the droplet separation efficiency predictions for small droplets are closer to the corresponding experimental data. The CFD simulation results showed that in the vane, enhanced with drainage channels, fewer low velocity sectors were observed in the gas flow field due to more turbulence. Consequently, the droplets had a higher chance of hitting the vane walls leading to higher separation efficiency. On the other hand, the parameters affect the liquid droplet trajectory leading to the changes in separation efficiency and hydrodynamic characteristic of the vane. To attain the overall optimum geometry of the drainage channel, all three geometry parameters were simultaneously studied employing 27 CFD simulation cases. To interpolate the overall optimal geometry a surface methodology method was used to fit the achieved CFD simulation data and finally a polynomial equation was proposed.     

Experimental and numerical analysis of a demister with vortex generators

An improved wave-plate demister equipped with vortex generators(VGs) has been proposed for wet flue gas desulfurization systems(WFGD) in this work. Numerical and experimental methods were used to evaluate the effect of VGs on the separation of small droplets. Five types of wave-plate demister with different VGs were analyzed. The vortex generators in question included rectangular plates, semi-elliptical plates, square tubes, round tubes, and triangular tubes, respectively. In order to explain the strengthening mechanism, the distribution of flow field, secondary flow, and droplet trajectory were shown, and the effect of VGs on the flow field in the demister was discussed in depth. The simulation results show that the separation performances of the demisters with VGs were significantly improved over that of the initial demister, and the accompanying pressure drop was small. For the vortex generators studied, the rectangular plate fully demonstrated its superior separation performance, followed by semi-elliptical plate. The strengthening effect of VGs was tested through experiments. Experimental data reveal that the average droplet diameter(D_(50)) at the outlet of the demister with a vortex generator can be reduced to 23.13 μm, whereas this value for the initial demister can be maintained at 32.07 μm. Moreover, compared with the original demister0.81, the overall separation efficiency of the improved demister was improved to 0.92.     

Spray and mixing characteristics of liquid jet in a tubular gas–liquid atomization mixer

For the design and optimization of a tubular gas–liquid atomization mixer,the atomization and mixing characteristics of liquid jet breakup in the limited tube space is a key problem.In this study,the primary breakup process of liquid jet column was analyzed by high-speed camera,then the droplet size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry (PDA).The hydrodynamic characteristics of gas flow in tubular gas–liquid atomization mixer were analyzed by computational fluid dynamics (CFD) numerical simulation.The results indicate that the liquid flow rate has little effect on the atomization droplet size and atomization pressure drop,and the gas flow rate is the main influence parameter.Under all experimental gas flow conditions,the liquid jet column undergoes a primary breakup process,forming larger liquid blocks and droplets.When the gas flow rate (Q_g) is less than 127 m~3·h~(-1),the secondary breakup of large liquid blocks and droplets does not occur in venturi throat region.The Sauter mean diameter (SMD) of droplets measured at the outlet is more than 140μm,and the distribution is uneven.When Q_g127 m~3·h~(-1),the large liquid blocks and droplets have secondary breakup process at the throat region.The SMD of droplets measured at the outlet is less than 140μm,and the distribution is uniform.When 127Q_g162 m~3·h~(-1),the secondary breakup mode of droplets is bag breakup or pouch breakup.When 181Q_g216 m~3·h~(-1),the secondary breakup mode of droplets is shear breakup or catastrophic breakup.In order to ensure efficient atomization and mixing,the throat gas velocity of the tubular atomization mixer should be designed to be about 51 m·s~(-1)under the lowest operating flow rate.The pressure drop of the tubular atomization mixer increases linearly with the square of gas velocity,and the resistance coefficient is about 2.55 in single-phase flow condition and 2.73 in gas–liquid atomization condition.     

可用于MVR蒸发系统的气液分离器改进结构分析

针对常规气液分离器对微小液滴分离效率低的不足,提出一种可用于MVR蒸发系统的气液分离器结构,并采用数值模拟结合实验验证的方法对其分离特性进行研究。首先,利用数值模拟的方法分析了气液分离器内部流场和压力场,确定了影响分离效果最明显的位置,然后提出了在该位置加装不同数量3/4圆环形挡板的分离器结构。其次,模拟研究了此种新结构的分离效率和压降等分离特性以及挡板数量变化的影响规律。最后,通过实验验证的方法分析了数值模拟结果的可靠性和新结构的分离效果。研究结果表明：圆柱型筒体是影响分离器分离特性的关键部位,在气液分离器圆柱形筒体内部增加3/4环形挡板,能够增加物料切向运动的有效长度,降低物料的径向速度,从而显著提高微小液滴的分离效率,气液分离器整体压降却增加不多;而且随着环形挡板数量的增加,该结构气液分离器的分离效率和压降均明显提高。在本文计算条件下,加装3/4圆环形挡板的气液分离器结构,可以将直径在3 μm以下的液滴分离效率提高15%,而压降仅增加了200Pa。综合气液分离器效率和压降影响,加装两个3/4圆环形挡板的气液分离器性能最佳。     

折叠滤芯气液过滤性能测试及优化

采用聚结型滤芯气液过滤性能实验装置,研究了油雾加载率和表观过滤速度对折叠滤芯过滤性能的影响及涂覆粘合剂对折叠滤芯过滤性能的优化作用。结果表明,涂覆粘合剂后,滤材抗张力强度明显增大,滤材孔径减小。随油雾加载率增大,滤芯过滤层液体运移通道数增加,通道压降升高。初始压降随表观过滤速度增加而升高。粘合剂主要凝固在渗透性低的区域,压降变化较小。表观过滤速度增加抑制了二次夹带,折叠滤芯过滤效率升高,而由于粘合剂脱落,涂覆粘合剂的滤芯过滤效率下降。表观过滤速度为0.10 m/s时,随油雾加载率增大,聚结在滤材表面的粘合剂抑制夹带,滤芯过滤效率升高。     

气液交叉流系统除尘效率分析及其数值模拟

对采用以水为介质吸收含尘气体中颗粒物的气液交叉流系统（GLCA）进行实验研究,考察了气速、液柱排布方式、粒径等因素对脱除率的影响。结果表明,随着液柱比表面积和颗粒粒径的增加,脱除率逐渐上升;在实验条件下气速对脱除率影响较小。在最优液柱排布方式下,经过162单元液柱排后,粒径为0.2、1、10 μm的颗粒分别取得了37.3%、43.9%、99%的脱除率。给出了用于外推计算分级效率和压降随单元液柱排数变化的公式,当粒径为0.4 μm的颗粒预测脱除率达到95%时系统的总压降不超过300 Pa。采用大涡模型对最优工况进行数值模拟,模拟结果与实验数据吻合良好,以此验证了所给脱除率计算公式。     

多效旋风分离器性能的实验研究

多效旋风分离器通过采用2级螺旋管预分离含尘气体、螺旋形顶盖板导流、筒体中心稳流锥稳流和吸气回流系统防止粉尘返混等措施,解决了在旋风流场中分离微米及亚微米级颗粒的难题。文中通过实验研究了直径为0.25 m的多效旋风分离器的压降、分离效率和进口风速的关系,实验物料粒径范围为0.1—23μm,平均粒径为7.59μm。结果表明:在10—14 m/s入口风速时,对0.1—3μm颗粒的分离效率大于90%,对大于5μm颗粒的分离效率接近100%,压降在500—1 000 Pa。风速大于16 m/s时,对0.1—2μm颗粒的分离效率大于75%。