疏油改性对玻纤聚结元件气液过滤性能的影响

气液聚结元件在压缩气体净化等工业领域应用广泛，目前聚结元件的性能难以满足行业不断增长的需求，但是提高聚结元件过滤效率的同时，阻力也会随之升高，不利于其综合性能的优化。为研制低阻高效的聚结元件，利用不同浓度氟硅氧烷丙烯酸酯溶液对聚结滤材进行疏油改性，分析了表面能不同的滤材在气液过滤过程中压降、过滤效率以及二次夹带现象的变化，并对改性在聚结滤芯上的应用效果进行研究。结果表明，改性滤材在过滤效率提高10%的同时，稳态压降可降低约30%。滤材表面性质变化导致的跳跃压降减小是稳态压降降低的主要原因；滤材内液体分布对扩散、惯性分离作用的增强以及二次夹带的减少是效率提高的主要原因。对于表面能不同的疏油滤材，稳态压降和效率均随表面能的减小而升高。聚结滤芯经过改性后品质因子最大可提高92%。     

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。     

不同操作压力下的气液过滤特性分析

根据ISO-12500标准建立了压缩空气滤芯性能检测系统,将操作压力由0.1 MPa升至0.7 MPa,分析了操作压力对亲油型和疏油型两种滤芯内的液体分布、滤材饱和度和过程压降的影响. 结果表明,操作压力对疏油型滤芯的过程压降、液体运移与饱和度有显著影响,操作压力每上升0.2 MPa,滤芯初始压降上升0.32 kPa,各操作压力下滤芯润湿压降(平衡压降与初始压降的差)为4.5~5.1 kPa,0.7 MPa时最后1层滤材饱和度比0.1 MPa时上升了71%,饱和度沿气体流动方向呈凹型分布,小面积润湿区域增多,稳态压降前出现短暂跃升阶段,可能加剧滤芯二次夹带,导致过滤器下游管道内液滴数增多,降低过滤器效率;操作压力对亲油型滤芯的初始压降影响显著,操作压力每上升0.2 MPa,初始压降上升0.39 kPa;操作压力对液体运移与饱和度影响较小,不同操作压力下各层滤材饱和度的分布规律相同,液体分布无明显差异.     

孔径梯度分布对亲油型滤材气液过滤性能的影响

在天然气净化、大型旋转机械曲轴箱通风和压缩空气过滤等领域,气液聚结过滤器具有广泛的应用。利用滤材过滤性能实验装置,分析了气液过滤过程中不同孔径梯度分布的亲油型滤材的压降、穿透率和饱和度变化,比较了其过滤性能、内部液体分布特性以及对液滴二次夹带现象的影响。结果表明：在气液过滤过程“通道压降”阶段,孔径递增滤材压降和0.8 μm以上液滴穿透率的变化曲线具有明显的分层特征。不同孔径梯度分布滤材的稳态过滤性能存在明显差异,主要原因是滤材内部存在液体运移通道的传递现象。通过与孔径递减和孔径均匀分布滤材的稳态过滤性能对比,发现孔径递增滤材在保证较低压降的同时具有最高的品质因子,有利于减少液滴二次夹带现象的发生,且对0.8 μm以上不同粒径液滴均具有最高的过滤效率,即孔径递增滤材在气液聚结过滤器设计中更具优势。     

孔径梯度分布对亲油型滤材气液过滤性能的影响

在天然气净化、大型旋转机械曲轴箱通风和压缩空气过滤等领域,气液聚结过滤器具有广泛的应用。利用滤材过滤性能实验装置,分析了气液过滤过程中不同孔径梯度分布的亲油型滤材的压降、穿透率和饱和度变化,比较了其过滤性能、内部液体分布特性以及对液滴二次夹带现象的影响。结果表明:在气液过滤过程"通道压降"阶段,孔径递增滤材压降和0.8μm以上液滴穿透率的变化曲线具有明显的分层特征。不同孔径梯度分布滤材的稳态过滤性能存在明显差异,主要原因是滤材内部存在液体运移通道的传递现象。通过与孔径递减和孔径均匀分布滤材的稳态过滤性能对比,发现孔径递增滤材在保证较低压降的同时具有最高的品质因子,有利于减少液滴二次夹带现象的发生,且对0.8μm以上不同粒径液滴均具有最高的过滤效率,即孔径递增滤材在气液聚结过滤器设计中更具优势。     

压缩机润滑油雾滤芯过滤性能分析与改进研究

利用现场高压和实验室常压滤芯性能评价装置，对比了不同工况下的滤芯过滤性能，分析了液体物性和油雾浓度对滤芯过滤性能的影响规律，提出了滤芯改进方法并进行了效果验证。结果表明，由于气液相互作用改变，高压下滤芯过滤效率相比常压略低，但常压工况过滤性能变化规律能反映现场实际运行性能。与气体流量相比，液体黏度对中效滤芯的过滤效率影响更大，且滤芯在过滤高黏度液体时才会出现压降的显著上升。油雾浓度对中效滤芯的压降影响受液体黏度控制，高黏度时压降随油雾浓度升高而升高，但低黏度时压降基本不随油雾浓度变化。由于流量对液滴扩散捕集作用的影响，低流量时滤芯对高黏度液体的过滤效率随油雾浓度降低反而升高。通过调整滤芯内部的滤材组成及排布方式，可实现小尺寸液滴的高效捕集，对癸二酸二辛酯液滴的过滤效率相比原滤芯至少提升50%。研究结果对于指导天然气储运过程中滤芯性能提升与机理认识具有重要意义。     

亲油型聚结滤芯饱和度预测模型研究

纤维聚结滤芯广泛用于压缩空气净化、发动机曲轴箱通风、加工和切割等一系列工艺过程中，用于除去气流中的液体气溶胶颗粒。由于聚结滤芯饱和度对于过滤效率及阻力具有重要影响，因此建立饱和度与滤材参数及操作条件之间的关系将有助于优化滤芯结构并提高过滤性能。目前实际工业用聚结滤芯通常由多层微米级玻璃纤维材料组成，然而现有计算模型无法用于此类滤芯的饱和度预测。因此，本文基于多种常用亲油型聚结滤芯压降及饱和度实验测试结果，根据“跳跃-通道”模型及毛细管理论建立了新的饱和度预测模型。通过与大量已发表文献数据对比发现，当饱和值大于0.2时，预测值与实验结果吻合度较好，相对偏差≤20%。随着饱和度的降低，滤芯润湿区域和非润湿区域之间界限逐渐明显，此时无需对毛细管半径进行修正。然而，新模型仍然要依靠压降测量值进行计算，这一问题需在后续工作中加以解决。     

空气过滤用玻璃纤维滤材的油雾聚结性能及改性优化

为了提高滤材对油雾液滴的过滤性能,采用油雾聚结过滤性能测试评价系统,对比不同精度等级的空气过滤用滤材性能,建立滤材表面改性优化方法.结果表明:液滴在滤材表面呈现过渡润湿特征,且随着滤材精度提高,压降曲线增长率上升、液滴二次夹带现象增强,但对亚微米液滴的综合过滤性能呈现先增后减趋势;液体表面张力增大后,在纤维表面铺展性变...     

气液过滤过程中液滴二次夹带现象分析

在天然气长距离输送过程中,天然气夹带的液滴严重影响压缩机组的安全可靠运行。利用所建立的滤芯过滤性能检测装置,以癸二酸二辛酯为实验介质,分析了天然气净化用滤芯气液过滤过程中液滴二次夹带现象的特征,比较了滤材润湿性和过滤速度等参数的影响。结果表明:当滤芯仅由聚结层组成时,滤芯过滤过程中存在液滴二次夹带现象,二次夹带将导致下游气体中液滴数量增多,且有较大液滴出现,稳态阶段滤芯累积效率在大粒径处下降;液滴在滤材表面的润湿性对二次夹带现象具有重要影响,可润湿型滤材表面更易出现液滴二次夹带现象,在相同过滤速度下,若需提高过滤效率,宜选用不可润湿型滤材制作工业滤芯;在0.1～0.3 m·s^-1过滤速度范围内,提高过滤速度可减少液滴二次夹带现象的发生,与不可润湿型滤芯相比,可润湿型滤芯过滤效果的改善更为明显;滤芯增加排液层可有效消除液滴二次夹带现象。     

气体含液浓度对亲油型聚结滤芯压降及含液量的影响

针对天然气输送管路中气体含液浓度变化范围宽且严重影响滤芯正常使用的问题,为了分析气体含液浓度对滤芯压降和含液量的影响,以及研究不同层数滤芯应用于不同浓度工况下的可行性,利用滤芯过滤性能评价装置比较了0.07~1.00 g×m~(-3)不同气体含液浓度条件下不同层数滤芯的压降变化。结果表明:气体含液浓度通过改变滤材内运移液体的通道数目而对滤芯通道压降产生较大影响,浓度升高导致通道数目增多、通道形成时间缩短、滤芯各层含液量增多。同时发现,通道压降随气体含液浓度的增大呈非线性增长,其中气体含液浓度影响的滤材含液量是否达到饱和值,是通道压降急剧上升的关键。此外,滤芯层数通过影响通道数目而改变通道压降增长趋势,当气体含液浓度在0.2~0.4 g×m~(-3)时,增加滤芯层数,可以降低通道压降。建立的气体含液浓度、滤芯层数与通道压降的关系模型可为工程实际中滤芯结构优化和不同浓度工况下通道压降预测提供指导帮助。     

Influence of oleophobic modification on gas-liquid filtration performance of glass fiber coalescing elements

Gas-liquid coalescing elements are widely used in industrial fields such as compressed gas purification. Currently, the performance of coalescing elements is difficult to meet the growing needs of the industry. However, while increasing the filtration efficiency of the coalescing element, the resistance will increase simultaneously, which is not conducive to the optimization of the comprehensive performance. To develop low-resistance high-efficiency coalescing elements, the coalescing filter materials are modified by different concentrations of fluorosilicone acrylate solution. The evolution of pressure drop, filtration efficiency and secondary entrainment of the filter materials with different surface energy during the gas-liquid filtration process were analyzed, the modified filter materials were fabricated into coalescing filters for verification. The results showed that, the filtration efficiency of the modified filter materials was increased by approximately 10%, and the steady-state pressure drop was reduced by approximately 30%. The decrease in jump pressure drop caused by changes in the surface properties of the filter materials is the main cause of the decrease in steady-state pressure drop. The increase in filtration efficiency is caused by the enhancement of diffusion and inertial separation, and the reduction of secondary entrainment. For oleophobic filter materials with different surface energy, the pressure drop and filtration efficiency increase with the decrease of surface energy. The quality factor of the coalescing filter element can be increased by up to 92% after modification.     

高压工况对天然气滤芯性能影响的实验研究

为探究高压工况下天然气滤芯的过滤性能变化规律及影响因素,选取了四种规格的滤芯为研究对象,开展了现场实验和实验室性能测试。发现在现场运行410 d后,四种滤芯的压差平均增长约20%,在相同气固过滤实验条件下压差增长速率更大,而四种滤芯的过滤效率和品质因子的差异相对缩小。高压工况下过滤材料压缩了7%~31%,大量颗粒嵌入过滤材料或沉积在表面,各过滤层的透气度普遍下降,而抗拉强度均有所上升。结果表明,选用孔径分布均匀的纤维材料、过滤精度梯级设计的复合材料,对过滤层打褶以及采用导流式骨架,均有助于滤芯在高压运行工况下长周期稳定可靠运行。     

Comparative performance of philic and phobic oil‐mist filters

The evolution of pressure drop, drainage rate, saturation, and efficiency of combined philic, and phobic oil mist filters in real‐time are examined. The experiments used four different filter configurations, with a combination of oleophobic and oleophilic fibrous filter media, and one oleophilic only reference. The effect of separating filter materials of differing wettability, with a mesh, was also explored. It was found that inclusion of a mesh between layers promoted increased drainage rates and resulted in a significantly lower pressure drop across the filter. The overall mass‐based filtration efficiency was also slightly higher for the configurations containing the mesh. Conversely, re‐entrainment of droplets from the rear face of the filter was only observed in filter configurations without the central mesh. Filters with oleophobic initial layers did not display a classical “depth filtration” pressure drop curve. The oleophobic media was found to possess lower steady‐state saturation than oleophilic media. Additionally, the steady‐state saturation of the oleophilic filter media, when placed at the rear of the filter, was lower when the central mesh was present. The saturation values were compared with recently published theory. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2976–2984, 2014     

天然气用聚结过滤元件性能的测定与分析

为了评价目前天然气净化用滤芯气液分离性能,利用聚结型滤芯气液过滤性能的检测装置研究了滤芯的放置方式、滤芯的有效厚度及填充密度等相关因素对气液过滤性能的影响。结果表明：在相同条件下,滤芯垂直于地面放置比水平位置放置时排液较顺畅,气液过滤效果较好,并且压降至少降低25%;不同材质滤芯,随着滤芯厚度在6~32mm范围内增加,滤芯稳态压降增加,过滤器出口液滴浓度减小,过滤性能提高;滤芯的填充密度增加,滤芯压降增大,过滤器出口液滴浓度减小。     

Development of high efficiency particulate absorbing filter materials

We have developed new high efficiency particulate absorbing filter materials by bonding the fiber web with the help of high pressure water jets emerging from micron sized nozzles and subsequently coating the filters with a chemical binder. Two different types of nonwoven filters are produced by varying the water jet pressure during the bonding process. The performance characteristics of the filter materials are evaluated in terms of filtration parameters, such as filtration efficiency, dust holding capacity, and pressure drop. Filtration efficiency depends on the pore characteristics, namely pore size and their distribution in the filters. The developed filter materials have shown promising performance characteristics by capturing higher amount of dust particles with a relatively low pressure drop during use. These filter materials can be used for a wide range of industrial applications, where high filtration efficiency is required at low energy consumption. A fluid flow simulation is carried out by computational fluid dynamics (CFD) to understand flow pattern during the bonding process. The CFD is also used to predict the pressure drop in the nonwoven filter materials during filtration process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Experimental Study on Filtration Performance of Flat Sheet Multiple-Layer Depth Filter Media for Intake Air Filtration

Depth filter media are usually composed of multiple layers to attain optimal values of main filtration parameters such as pressure drop and particle collection efficiency (PCE). Understanding the performance of the single layers that make up the filter media can contribute to attaining these optimum values. For the purpose of this study, we have developed two samples of depth filter media, 2LM and 3LM, composed of two and three layers, respectively. Samples of the media and single layers have been prepared in flat sheet form. Filtration performance of these samples has been evaluated using a lab-scale flat sheet filter media test unit with KCl as the test aerosol. Results from these tests have been compared with those from an automated filter tester (AFT) with NaCl as the test aerosol. These media have been characterized based on filter media properties and data from the filtration performance tests and the effect of layers on filtration performance has been observed. Pressure drop data from the tests with a standard test unit and our laboratory test unit are similar, and the difference in data is attributed to high inlet concentration of KCl particles. The overall filtration performance is strongly dependent on the final layer regarding pressure drop and particle of two- and three-layer filter media. Other constituent layers can be seen as contributors to the dust-holding capacity of the filter media and can reduce the dust load for the final layer.

Copyright 2013 American Association for Aerosol Research     

静电纺丝纤维滤材表征及其气液过滤性能

以聚丙烯腈与二甲基甲酰胺为原料配制纺丝溶液,采用静电纺丝技术制备玻璃纤维/聚丙烯腈纤维/玻璃纤维三层复合滤材,研究了纺丝溶液浓度与纺丝电压等参数对纤维形貌及尺寸的影响,分析了复合滤材的过滤性能. 结果表明,控制不同纺丝溶液浓度可得形貌不同的纤维,且溶液浓度越大纤维尺寸越大;纺丝电压对纤维形貌的影响较小,但增加纺丝电压使静电纺纤维层的孔径减小. 相比玻璃纤维滤材,复合滤材过滤效率明显提升,稳态效率最大可提升21%,最易穿透粒径效率最大可提升39%,但复合滤材孔径较小时,过程压降增加了一段跳跃阶段,纳米纤维层表面形成液膜,使复合滤材稳态压降升高.