涡发生器对脱硫系统除雾器性能的影响

通过数值模拟研究了平板、椭圆板、圆管、方管和三角管5种涡发生器分别安装于湿法烟气脱硫系统折流板除雾器中的除雾效率与压降。采用欧拉-拉格朗日方法分别求解气相-液相运动状态,入口流速U _in为3~6m/s,液滴直径范围2~80μm。结果表明,平板的除雾效率与压降增大最多,U _in=3m/s时,除雾效率相比无涡发生器高31.98%,压降高30Pa。平板对2μm液滴具有较高的除雾效率,最大为34.88%,比无涡发生器高20.81%。椭圆板U _in=3m/s时除雾效率比无涡发生器增加29.14%,压降升高20.47Pa。圆管、方管和三角管的总除雾效率分别高达95.05%、97.49%和96.48%。压降方面,方管为无涡发生器的4.18倍,圆管和三角管分别为2.05倍和2.79倍。另外,考察了椭圆板攻角的影响。在相同U _in下,除雾效率随着攻角的增加而增大,50°的椭圆板除雾效率为97.09%~99.15%。攻角对2μm液滴的分级除雾效率影响不大。压降随着攻角的增大而增加,U _in=4m/s时,攻角从0°增加到50°,压降从25.3Pa增加到92.78Pa。椭圆板因其迎流面积与长宽比的匹配以及流线型产生了较多涡流,具有良好的强化除雾效率效果以及较小的压降。     

惯性分离装置的性能分析及结构优化

通过搭建惯性分离装置测试平台，结合相关检测设备的数据采集，进行某型惯性除雾器的性能分析。实验发现，两通道折流惯性分离装置的分离效率与液滴直径成正比。对于微小粒径5～10μm的液滴分离效果不佳，风速对分离效率的影响不大。对于30μm以上的液滴分离效果较好，效率整体超过80%。系统进出口压降损失方面，粒径的变化相对于整个装置可以近似忽略，不同粒径条件下压降曲线变化基本相同，风速是压降变化的主要影响变量。为突破小粒径液滴分离效果不佳的限制，分别从板间距、底面高度及板型等方面入手，分析不同尺寸参数条件下分离效率与压降的变化规律。计算结果表明，板间距数值越大，分离效率越低，系统压降越小；底面高度与效率变化并不是总体相关，存在波动并呈现局部相关性；高度增加到30mm时达到最佳，系统压降也较小；通道级数越多，分离效率越高，但压降增加较大；流线型壁面分离效果较好，控制压降的能力也较强。     

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.     

平直和柱面小翼涡发生器诱发流动特性PIV实验研究

在Re=700、攻角α=60°时,利用粒子图像测速技术(PIV)研究了矩形通道内平直和柱面小翼诱发的流动结构,获得涡发生器(VG)后1~3倍弦长距离的速度场和涡量场。结果表明,三角小翼的涡结构主要分布在斜边中心和后缘角区;梯形和矩形小翼的涡结构主要分布在前缘翼梢区域和后缘区域;此外,柱面梯形小翼中心区域的涡结构明显,影响范围最大。随着流动的进行,涡结构强度逐渐减弱,三角小翼仅维持一个主涡向下继续运动;梯形和矩形小翼也仅维持一个主涡和一个后缘角涡的结构。随着斜截角的减小,前缘和中心区域诱发高强度涡结构的能力增强,影响范围也广,而后缘角涡的影响范围较小,且与底部壁面的距离较远。     

新型多旋臂气液分离器入口旋流头的预分离特性研究

新型多旋臂气液分离器可实现大直径分离器内的气液旋流高效分离,其入口旋流头结构是分离器的重要组件之一。通过大型冷模实验,对入口旋流头结构的液滴群粒径分布进行非引出式在线测量,从压降和分离效率角度考察了旋流头的预分离性能。结果表明,在入口直管段,初始液滴粒径会在高速气流的作用下迅速进行重新分布,粒径分布呈类正态分布,Sauter平均粒径（SMD）为16.8 μm。在16.95 m/s的气速下,液滴群在H/D=2.47~8.48长度内的入口直管段中运动状态稳定,粒径分布未发生明显变化。在高气速的操作条件下,剪切效应和边壁效应共同作用使SMD略有增大。液滴群在流经旋流臂后,粒径分布发生显著变化,出现“双峰”特征,旋流臂对液滴的聚集效果明显。通过粒径分布分析,预测了旋流臂末端的液滴特征。发现旋流头的预分离性能优越,在压降占比仅3.2%~8.4%的情况下,分离效率占比可高达42.8%~62.5%。入口旋流头结构不仅可以为混合相创造强旋流的初始分离环境,还能借助自身结构特点实现对混合相的惯性预分离。     

折板式汽液分离元件的性能

采用空气-水体系,对折板式汽液分离元件进行冷态模拟实验,研究了气速、液滴粒径、折板形式、间距及安装方式等参数对折板分离效率和压降的影响. 结果表明,气速控制在1~6 m/s,液滴粒径控制在50~80 mm,折板采用立式和卧式安装,形式采用V形和W形,间距为10~50 mm,对分离性能均有一定的影响,折板间距为20 mm的分离元件具有较高的分离效率. 通过对冷态实验数据进行数学回归分析,获得描述折板性能的经验公式,与实验值误差在10%内,同时在海水淡化中试试验装置中验证了折板式汽液分离元件的分离性能.     

扁管换热器内纵向涡强度与换热强度对应关系

纵向涡强化传热技术在管翅式换热器中得到了广泛的应用。但是一直以来对纵向涡强化传热的研究主要停留在涡产生器结构参数及布置方式对换热的影响方面,文献对纵向涡强度与换热强度之间定量关系的研究鲜有报道。建立了采用纵向涡强化传热的扁管管翅换热器数值模型,采用二次流强度参数Se分析了翅片及涡产生器结构参数变化时,通道内纵向涡强度与换热强度之间的定量关系;并定量分析了通道中涡产生器引起的纵向涡强度增量与传热强化量之间的定量关系。结果表明:翅片及涡产生器结构参数变化时,Nu、Se与Re之间,以及阻力系数f与Re及Se之间均不存在定量对应关系,但Se与Nu以及ΔSe与ΔNu之间存在对应关系。这表明,在布置有纵向涡产生器的扁管管翅换热器翅侧通道内,纵向涡强度决定了通道内的换热强度。     

内插不同形状涡产生器管内层流流动与传热特性的对比分析

内插扰流元件是一种可操作性强的管内强化传热方式,其强化传热机理主要是在管内诱导产生了二次流。在均匀壁温热边界条件下,对内插不同形状涡产生器管内层流流动与传热特性进行了数值分析。研究发现：在扭带基础上裁去部分面积相同的条件下,管内插等腰梯形涡产生器的换热能力最强,直角梯形涡产生器次之,矩形涡产生器的换热能力最差,管壁上的局部Nusselt数的峰值所在圆周位置及其大小与涡产生器形状有关,而不同形状的涡产生器对管内流动的阻力系数影响较小。插入涡产生器后,管内二次流强度参数Se和平均Nusselt数Nu均随Reynolds数Re的增大而增大,二者随Reynolds数Re的变化规律具有一致性。平均Nusselt数Nu与二次流强度参数Se呈幂函数相关,内插涡产生器管内的二次流强度决定了其对流换热强度。     

Influence of the plate-type continuous micro-separator dimensions on the efficiency of demulsification of oil-in-water emulsion

The objective of this article is to find the optimal dimensions of rectangular plate-type micro-separators in order to enhance the continuous separation of immiscible liquids. The main structure of the separators contains two plates: a hydrophobic (PTFE) upper plate and a hydrophilic (stainless steel) bottom plate which formed the contact surfaces for the fluids in the channel. The devices have two outlets, one for the aqueous phase and the other for the organic phase enabling the continuous separation and withdrawal of the separated phases. Demulsification has been carried out using Shellsol/water emulsion in the presence of a non-ionic surfactant (Tween 80). The separation efficiency is investigated as a function of micro-separator sizes, channel depths, flow rates and plate configurations. The major parameter that controls the destabilization mechanism is the ratio between the droplet size and the channel depth. When the size of the dispersed droplets remains smaller than the height of the separator (channel depths: 25–100 μm), creaming is the main demulsification mechanism. Creaming refers to the migration of the dispersed phase of an emulsion, under the influence of buoyancy. The particles float upwards and rise to the top due to the difference in the densities of the particles and the medium. The separation efficiency depends mainly on the residence time of the liquid/liquid mixture in the device regardless of the separator dimensions and channel heights. The separation rate is limited by the removal of the cream layer, formed at the top of the upper plate, from the separator. When the size of the dispersed droplets is larger than the depth of the separator (channel height of 9 μm), the separation performance and mechanism become different. The coalescence of the dispersed droplets occurs by passing through the device. The comparison of the data corresponding to creaming and coalescence phenomena emphasizes that the coalescence greatly enhance and accelerate the separation action. The phase separation in the micro-coalescer takes place considerably faster than in the micro-separators.     

小尺度涡流发生器强化传热的数值模拟

采用数值模拟方法,对布置有不同高度小尺度涡流发生器的矩形槽道,在Re=4000～10000的范围内进行了模拟计算。结果表明,小尺度涡流发生器由于其高度的不同引起对流换热和压差的变化,分析了小尺度涡流发生器所诱导的流向涡和展向涡对强化传热影响的内在机理,并对所产生的涡旋对槽道中压力分布的变化进行了分析。采用一种综合考虑对流换热和流动阻力的评价标准对不同高度小尺度涡流发生器的传热和流阻特性进行对比评价。     

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。     

优选结构液-液旋流管分离特性

利用库尔特粒径检测技术,对一种优选结构液-液旋流分离管的分离特性进行了较为系统的实验研究。实验测得该旋流管的临界分离粒径为30μm,而相同条件下国外典型产品,即F型旋流管的临界分离粒径为60μm,表明这种优选结构旋流管的分离特性较F型旋流管显著改善;实验结果还表明该旋流管的分离特性随处理量的增加而提高,当处理量为10m~3·h~（-1）时最好;随溢流比的加大而改善,其最佳溢流比为4％～5％;此外,还考察了为含油浓度与粒径分布之间的关系。有关结果为科学严格地评价液-液旋流分离管的分离性能提供了科学依据。     

玻璃纤维聚结器脱除油中乳化水

随着油水分离技术的进步及新材料的开发,聚结法脱除油中乳化水的技术得以实现。本文采用亲水性玻璃纤维作为聚结元件,脱除白油中的乳化水（d₉₅=10μm）。通过实验考察聚结器中进料的表观流速（5~30m/h）、油品初始含水量（500~4000μL/L）、聚结器床层厚度（100~400mm）和玻璃纤维的孔隙率（0.80~0.95）对聚结分离效率的影响,并应用响应面法对各变量之间的协同效应进行分析,确定最佳操作条件,分析该条件下的粒级分离效率。实验结果显示,当表观流速为14m/h、初始含水量为1278μL/L、床层厚度为275mm和孔隙率为0.85时,分离效率最高,为95.18%。结果与响应面预测值（95.02%）相比,相对误差仅为0.17%,表明回归模型的可靠性高和实验的重现性较好。进出口粒径的分析表明聚结器的分离效果随水滴粒径的增加而提高,有效分离粒径>5μm。本文研究结果对采用玻璃纤维为聚结元件,分离密度差较大的成品油中乳化水的聚结器选型及操作参数设计具有实际应用价值。     

Multi-objective optimization of drainage-plates in wave-plate mist eliminators using experiment and data-driven modelling for lower water loss and energy requirement

Wave-plate mist eliminators are widely employed as gas–liquid separation devices to prevent the liquid escaping from thermal power plants or other cooling towers. In this study, the wave-plate mist eliminator with drainage plates was numerically analyzed and the effects between geometrical variables on two objectives, namely, pressure drop (ΔP) and separation efficiency (η), were revealed. Plate spacing, width, and length, as well as the relative position of the drainage plate, were thoroughly investigated. A combined strategy was developed for multi-objective optimization of the wave-plate mist eliminator by integrating computational fluid dynamics (CFD) simulation, response surface methodology (RSM), non-dominated sorting genetic algorithm-II (NSGA-II), and a technique for order of preference by similarity to ideal solution (TOPSIS) method. The results demonstrated that the relative position of drainage plates has a greater impact on the overall performance, whereas the width of drainage plates has the minimum effect. With the implementation of NSGA-II and the TOPSIS method, an optimal solution for the design of the mist eliminator was obtained. After comparing with the baseline case, the optimized case presents promising characteristics with high separation efficiency (enhanced by 3.6%~9.06%) and a low energy consumption coefficient (reduced by 72.30% at η = 45%).     

换热器通道内反向旋转纵向涡间的干涉特性

纵向涡能以较小的压力损失获得较大程度的传热强化,在换热器空气侧强化传热中得到了广泛应用。换热器通道内通常存在多个纵向涡,纵向涡之间的干涉会不可避免地影响纵向涡的强度和强化传热性能。建立了换热器通道中旋转方向相反的两个纵向涡之间的干涉模型,通过数值方法分析了不同涡产生器横向间距下纵向涡之间的干涉现象。通过纵向涡强度定量研究了涡间干涉对纵向涡强度、流动阻力以及强化换热的影响。结果表明:旋转方向相反的两个纵向涡之间的干涉随着涡产生器间距的减小而增大;在涡产生器间距为零时纵向涡间干涉程度最大,纵向涡强度Se、Nu以及阻力系数f的变化量均达到最小值;在本文计算参数范围内,纵向涡引起的Se和Nu的变化量最大差别达到45%和50%,f的变化达到38%;纵向涡干涉并非一定不利于换热,纵向涡干涉后的流动结构影响其强化传热性能。在涡产生器横向间距为涡产生器底边横向投影长度的2倍时,可以利用纵向涡干涉获得最佳传热性能。     

催化裂化提升管末端旋流快分系统消涡板结构的数值模拟

在大型冷模实验基础上,采用RNG k-ε湍流模型对一套φ572 mm×3000 mm的旋流快分系统（SVQS）装置上部气体引出空间加设消涡板前后的气相流场进行了模拟研究。结果表明：在旋流快分上部空间加设两种不同结构消涡板都可以有效缓解边壁处的高速旋涡区。通过对比发现：在沉降器内壁面加装消涡板可以有效降低压降,降低消涡板上方气流即螺旋程度。直型消涡板压降较小,优于加装弯型消涡板。     

利用受限空间装置从低浓度水包油乳状液中分离油相的研究(英文)

A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.     

纵向涡发生器在管翅式换热器中的应用及优化

纵向涡发生器能够在较大幅度提升换热器换热能力的同时,较小幅度地增加其流动阻力。利用三维数值模拟的方法,详细分析和研究了纵向涡发生器对管翅式换热器传热流动的影响;并对纵向涡发生器的关键参数（攻角,数目,摆放位置）进行了优化。结果表明：纵向涡发生器的攻角为15°,采用3对矩形小翼时,管翅式换热器的空气侧换热能力的提升幅度超过了其流动阻力增加的幅度,与未采用强化措施的换热器相比,其空气侧传热系数提升了71.3%～87.6%,相应的流动阻力增加了54.4%～72%;空气侧的换热能力随着纵向涡发生器数目的增加而逐渐变大,但空气侧的局部换热能力在第5根换热管之后几乎不受涡发生器数目的影响;与纵向涡发生器的顺排布置相比,纵向涡发生器以交错叉排的方式布置时,可以在保证强化换热水平的同时,进一步减小换热器流道内的流动阻力。     

Reduction of milk fouling inside gasketed plate heat exchanger using nano-coatings

Fouling inside gasketed plate heat exchangers used in milk production has been reduced using nano-composites coatings. An antifouling coating with low surface energy (low wettability) led to a hydrophobic and oleophobic effect. Test facilities were constructed by the Institute of New Materials (INM) and Institute of Environmental Process Engineering (IUV), University of Bremen in Germany for the investigation of milk adhesion and the stability of the coatings on rectangular plates and small cylindrical ducts. A number of coatings and surface treatments were tested. Certain polyurethane-coated plates and tubes formed thinner deposit layer compared to standard uncoated stainless steel plates and tubes. The cleaning time for one coated tube was reduced by 80% compared to the standard stainless steel one. A pilot plant including a milk pasteurizer at LUFA Nord-West in Oldenburg-Germany was used for the thermal treatment of whey protein solutions. Plates coated with different nano-composites as well as electropolished plates were installed in the heating section of the pasteurizer. Significant differences were observed between coated and uncoated plates. The coated plates showed reduced deposit buildup in comparison with the uncoated stainless steel plates. Polyurethane-coated plates exhibited the thinnest deposit layer. Electro-polished plates also reduced deposit buildup in comparison to the standard stainless steel plates and were almost comparable to the coated plates. The time required for cleaning in place (CIP) with the coated plates was reduced by 70% compared to standard stainless steel plates.     

闪蒸罐除沫器损坏原因分析与处理措施

针对GE煤气化工艺黑水处理过程中,高压闪蒸罐旋流板式除沫器在运行过程中多次出现叶片断裂损坏的问题,采用理论核算和实际调查等方法,从除沫器的初始设计、工艺操作、设备维修制作方面进行了分析论证。结果发现,引起除沫器损坏的主要原因是流经除沫器的气相负荷为原设计的1.5倍左右,导致除沫器的穿孔动能因子超出正常取值范围。结合实际并在重新计算后调整了除沫器旋流板组件的结构参数,使除沫器的穿孔动能因子在运行过程中处于正常取值范围,且现场实施后叶片断裂问题得到根治,取得了良好的效果。