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。     

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°。     

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。     

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。     

Al_2O_3和SiC微滤膜的疏水改性及其油固分离性能研究

以正辛基三乙氧基硅烷和乙醇分别作为改性剂和溶剂,采用接枝聚合法对平均孔径为500 nm的Al_2O_3膜和SiC膜进行疏水改性,考察了改性剂浓度、改性液温度和改性时间对膜表面疏水效果的影响,并对比了疏水改性前后两种陶瓷膜的表面性质及疏水改性后的油固分离性能,进行了反冲实验和稳定性测试。结果表明,两种陶瓷膜材料在改性剂浓度为0.2 mol·L~(-1),改性液温度为40℃,改性时间为12 h时,疏水改性效果最好,得到的疏水Al_2O_3膜和SiC膜的水接触角分别为134°±1°和140°±1°,经改性后的SiC膜的疏水效果优于Al_2O_3膜。在油固分离实验中,疏水Al_2O_3膜和SiC膜均对固体炭黑有良好的截留性能,但疏水改性对SiC膜的油品通量提升更为显著,两种膜的稳态通量分别为1134 L·m~(-2)·h~(-1)和1408 L·m~(-2)·h~(-1)。反冲操作对疏水SiC膜的通量恢复更有利。     

中空纤维膜组件分离酸性气体

研究了气体膜分离与溶剂吸收相结合的分离技术.以NaOH水溶液为吸收剂,在中空纤维膜组件中实现二氧化硫气体的选择性吸收.研究了在三种不同结构的疏水性聚丙烯中空纤维膜组件中,吸收剂浓度、液速、气速、气液两相在膜组件内的流程、膜结构等对分离过程的影响;根据膜结构的实际参数确定了多孔膜的曲率因子,总传质系数的计算值与实验值相符.     

膜吸收CO2工艺中不同吸收液对膜润湿的影响

以单乙醇胺（MEA）、二乙醇胺（DEA）和N-甲基二乙醇胺（MDEA）作为吸收液,利用聚丙烯（PP）中空纤维膜组件进行分离模拟烟气中CO₂的实验研究,考察不同吸收液的脱除效率以及长时间连续运行下的膜润湿现象。建立膜相传质阻力随时间变化模型,与实验数据拟合较好。同时将膜丝在不同吸收剂中浸泡,结合接触角、场发射扫描电镜（FE-SEM）、衰减全反射红外光谱（ATR-IR）以及热重（TG）表征分析膜性能的改变。结果表明,相同浓度下,单一吸收剂的CO₂脱除效率大小为MEA > DEA > MDEA;当吸收液为1mol/L MEA时,16天后CO₂脱除效率从93.3%下降到72.1%;而吸收液为1mol/L DEA时,脱除效率从88.3%到第16天的78%,下降约12%;理论计算得吸收液为1mol/L MEA和1mol/L DEA时,膜相传质阻力分别为10564.06s/m和4881.08s/m;浸渍时间增加,膜接触角减小,疏水性减弱,同时膜孔径变大,出现润湿现象;红外光谱和热重分析表明在MEA溶液作用下膜丝出现溶胀。     

Al2O3和SiC微滤膜的疏水改性及其油固分离性能研究

以正辛基三乙氧基硅烷和乙醇分别作为改性剂和溶剂,采用接枝聚合法对平均孔径为500 nm的Al₂O₃膜和SiC膜进行疏水改性,考察了改性剂浓度、改性液温度和改性时间对膜表面疏水效果的影响,并对比了疏水改性前后两种陶瓷膜的表面性质及疏水改性后的油固分离性能,进行了反冲实验和稳定性测试。结果表明,两种陶瓷膜材料在改性剂浓度为0.2 mol·L^-1,改性液温度为40℃,改性时间为12 h时,疏水改性效果最好,得到的疏水Al₂O₃膜和SiC膜的水接触角分别为134°±1°和140°±1°,经改性后的SiC膜的疏水效果优于Al₂O₃膜。在油固分离实验中,疏水Al₂O₃膜和SiC膜均对固体炭黑有良好的截留性能,但疏水改性对SiC膜的油品通量提升更为显著,两种膜的稳态通量分别为1134 L·m^-2·h^-1和1408 L·m^-2·h^-1。反冲操作对疏水SiC膜的通量恢复更有利。     

疏水膜气液分离预处理纳氏试剂分光光度法测定氨氮适用性研究

采用疏水膜气液分离预处理纳氏试剂分光光度法检测水质样品中氨氮，根据测定结果分析方法的校准曲线相关系数、检出限、精密度和准确度等性能参数，同时与传统标准方法《水质氨氮的测定纳氏试剂分光光度法》(HJ 535—2009)进行比对实验。实验结果表明，疏水膜气液分离预处理纳氏试剂分光光度法测定氨氮时，氨氮含量在0.0～100.0μg/L范围内线性相关系数为0.999 2,线性关系良好；疏水膜气液分离预处理纳氏试剂分光光度法测定氨氮的检出限为0.008 mg/L,测定下限为0.032 mg/L;疏水膜气液分离预处理纳氏试剂分光光度法测定低质量浓度地表水、中质量浓度生活污水和高质量浓度工业废水样品的氨氮精密度在1.9%～3.1%之间，精密度良好；疏水膜气液分离预处理纳氏试剂分光光度法测定4种不同浓度氨氮有证标准物质的相对误差范围在-2.8%～1.2%之间，准确度较高。采用疏水膜气液分离预处理纳氏试剂分光光度法和传统标准方法HJ 535测定实验用水、地表水、生活污水和工业废水，测定结果显示2种方法无显著差异，2种方法的实际样品加标回收率也均符合国家相关质量控制要求。疏水膜气液分离预处理纳氏试剂分光光...     

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.     

Atomization of liquids and suspensions with hollow cone nozzles

Large centrifugal forces of rotational flow are used in hollow cone nozzles to form a thin liquid film in the outlet, which disintegrates into relatively small droplets. The flow in the nozzle can be calculated by means of simple physically meaningful balances, based on the cyclone theory. The influence of wall friction is taken into account via a wall friction coefficient which depends on the Reynolds number of the nozzle flow. The break-up mechanism of the liquid film was investigated under the consideration of nozzle outlet velocity and film thickness as well as gas and liquid properties. With increasing velocity and film thickness, a transition from aerodynamic wave break-up to turbulent atomization was observed to take place. Equations presented in this paper allow the calculation of mass flow rate, pressure drop and drop size distribution of hollow cone nozzles with any given geometry.     

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。     

含聚浓度对旋流器性能影响的数值模拟与试验

以螺旋导流式旋流器为研究对象,选用幂律流体模型和离散相模型（DPM）计算了不同含聚浓度条件下的分离性能,对旋流器流场（速度场、压力场）及油滴运移特性进行了细致的分析,并采用高速摄像技术（HSV）开展了相应的分离特性试验。研究发现：聚合物浓度为0时,油滴存在明显的乳化效应,实测效率81.7%;浓度增大后,乳化效应减弱,油滴分散在旋流器内,中心油核消失,效率急剧下降,4000mg/L时旋流器基本无分离效果;浓度增大对压降影响较小,底流压降最高增幅5.6%,最大值不超过200kPa。分析表明,效率下降与切向速度衰减、径向压力梯度减小有关;浓度增大后油滴轴向向下运动的距离增加,呈现向旋流器外壁面运动的趋势,分离时间延长。     

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。     

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。