入口粉尘浓度对新型旋流-颗粒床耦合分离器特性的影响

通过大型冷模实验,考察了入口粉尘浓度对某连续操作新型旋流-颗粒床耦合分离器压降和除尘效率的影响特性。结果表明,入口粉尘浓度越大,达到平衡时分离器的压降越大,压降增速越快,入口粉尘浓度为59.13 g/m3时,分离器平衡压降最大为1.2 kPa;入口粉尘浓度越低,分离器分离效率越高。分离器颗粒床层内捕集颗粒含尘量与再生效率有关,再生尘源浓度越小,分离器压降达到平衡越快。当再生尘源浓度由58.18%降至23.67%,装置压降由1.5 kPa降至1.2 kPa;随着再生尘源浓度降低,分离器除尘效率略微下降。入口粉尘浓度和再生尘源浓度对分离器压降影响的结果一致,对分离器效率影响的结果不同。     

含尘含油高温热解煤气除尘技术研究进展

高温热解气除尘问题是影响煤热解技术实现规模化应用的重要问题之一。针对高温热解煤气所携带粉尘的特点,分析了含尘含油热解气高温除尘技术的研究进展,论述了高温热解气除尘技术的特点,根据含尘热解气高温除尘技术的特点提出了热解气除尘技术未来的研究方向。高温含尘热解气具有组成复杂、对温度敏感、重质组分容易冷凝、粉尘粒径小、分离难度大等特点。旋风分离器用于高温热解气除尘,对于粒径大于10μm的粗粉尘除尘效率较高,一般用作高温热解气除尘的预分离器。静电除尘技术、金属微孔过滤除尘技术(金属膜除尘技术)和颗粒床除尘技术对高温含尘热解气中粒径较小的粉尘除尘效率较高,适合进行精细除尘。现有热解气除尘技术试验结果表明,过滤温度过低,焦油容易冷凝,造成油气收率下降,温度过高,热解气二次反应加剧导致过滤过程积碳严重,影响除尘器运行周期。高温含尘热解气的除尘效率方面,金属微孔除尘技术的过滤效率最高,过滤效率大于99%,颗粒床除尘器用于高温热解气除尘的过滤效率大于90%,受温度影响,温度高于400℃的条件下,静电除尘器的过滤效率一般低于90%。在相同过滤时间内,金属微孔过滤技术的过滤压降最高,静电除尘器压降最低,颗粒床过滤器的压降介于两者之间。静电除尘技术具有压降低、除尘效率低的"双低"特点,因此,在工艺条件优化的基础上,开发新型电极材料成为其发展方向。金属微孔过滤除尘技术具有过滤效率高和压降高的"双高"特点,开发低成本、耐高温、耐腐蚀的抗积碳材料,调控金属网孔的结构与分布是金属丝网除尘技术的发展方向。颗粒床除尘过程中存在床料积碳、热解气二次反应等问题,未来开发新型除尘滤料实现除尘提质一体化将是颗粒床除尘技术的重要研究方向。各种除尘技术用于热解气除尘均有其独特特点,充分利用各种技术的优点,通过技术组合有望实现除尘工艺技术的高效稳定运行。目前,热解气除尘技术基本都处于中试及示范工程阶段,但中试时间一般较短,缺乏长期的运行数据,热解气除尘技术实现工程应用需要进一步研究。     

玻璃炉窑运行时间对陶瓷纤维催化滤管的影响

对不同运行时间的玻璃炉窑陶瓷纤维催化滤管进行脱硝性能、压降与显气孔率、C-环强度、SEM-EDS等检测与分析。结果表明，随运行时间的增加，玻璃炉窑陶瓷纤维催化滤管脱硝效率略有下降，其原因可能是粉尘中的钠、钙、镁等碱金属及碱土金属造成催化剂中毒以及粉尘在表层集聚和板结覆盖了部分催化剂活性位点。随运行时间的增加，压降逐年上升，显气孔率基本保持不变；C-环强度平均值稍有下降，而最小值略有增强。经扫描电镜观察，滤管表面被粉尘附着，表层存在粉尘搭桥和板结现象，而中层和内层仅存在微量粉尘，除尘性能优良。     

气固顺流式移动床过滤器的除尘性能

为了探究气固顺流式移动床过滤器的除尘性能。通过在大型冷模实验中改变表观气速、颗粒循环强度、粉尘在过滤器中的比沉积率σ等操作参数,考察了过滤器的两个重要性能参数——操作压降和捕集效率的变化。实验发现,随着表观气速增大,设备的压降随之增大,设备的除尘效率呈下降趋势。随着粉尘的比沉积率σ增大,稳定后的操作压降也会有所增长,但操作压降的稳定性随着比沉积率的增大呈现"不稳定-趋于稳定-不稳定"的趋势,设备的过滤效率先逐渐增大,而后降低。当表观气速u_g为0.126 m×s~(-1),比沉积率σ为0.000 735时,过滤器的操作压降可以达到相对稳定的状态,此时除尘效果最优,捕集效率可达97%以上。     

连续重整烧结金属过滤器的过滤和反吹

在连续催化重整过程中,贵金属催化剂因磨损会产生粉尘。收集粉尘既保护下游设备,又具有经济效益。烧结金属过滤器具有可靠、高效的过滤性能,已在连续重整催化剂除尘领域得到了广泛的应用。针对烧结金属过滤器在线再生不彻底,以及反吹气对工艺系统扰动较大的问题,研究了一定过滤压降增量下,反吹压力及脉冲宽度对过滤器再生效果及系统的影响,确定了烧结金属过滤器在线反吹的适宜操作条件。这对烧结金属过滤器在连续重整工艺中的应用具有一定的指导作用。     

可清洁式粉尘过滤测试系统清灰影响因素研究

袋式除尘器是工业常用的高效除尘设备,滤料及滤料再生是其能稳定运行的关键。本实验搭建了可清洁式粉尘过滤特性测试系统,提出了以残余压降、压力上升速率和清灰周期来表征清灰效果,探究了不同喷吹时间和喷吹压力对清灰效果和过滤效率的影响。结果表明当喷吹压力Pb为0.5MPa,喷吹时间τ为0.2s时,第一个残余压降为360.1Pa,第一个清灰周期为400s,当τ增大到0.5s、0.8s时,对应的残余压降下降47.6%、51.3%,清灰周期提高75.0%、107.5%,且压力上升速率也相对应下降,说明喷吹时间变大清灰效果更好,但并不呈现线性变化。当提高喷吹压力时,也出现相似的变化规律。     

入口抽滤预团聚提高旋风分离器性能试验研究

分析了旋风分离器对细粉捕集效率低的原因,并提出了对传统旋风分离器的改进方案,即将传统旋风分离器的排气芯管改进为一个过滤筒,并在滤筒内部加装转动清灰刷,这样的设计充分利用了旋风分离器和过滤除尘器各自的优点,使过滤除尘和旋风除尘有机结合在一起,节约了设备空间,提高了其综合性能,实验结果表明除尘总效率一般都在99.94%以上,完全除去了1.6μm以上的细粉尘。     

不同滤料固定颗粒床过滤性能对比

在固定床冷态实验装置上研究了平均粒径和稳态过滤压降相近、颗粒形状和表面状况不同的两种滤料(陶瓷球和石英砂)的过滤性能. 结果表明,两种滤料过滤性能变化规律基本一致. 粉尘沉积量(?m)增加,过滤效率先增大后减小,过滤压降偏离稳态过滤压降程度(G)增大. ?m相同时,过滤效率和G均随过滤气速增大而减小,但过滤后期高气速下G与低气速下接近. 增大入口粉尘浓度,总体过滤效率无明显改变,粒径大于0.7 ?m的粉尘过滤效率提高,G更显著. 两种滤料难过滤粉尘粒径均为0.35~0.6 μm. 因颗粒形状和表面状况不同,两种滤料过滤性能存在差异,其它条件相同时,石英砂总体和分级过滤效率均高于陶瓷球,G也较大;增大入口粉尘浓度,石英砂过滤效率随粉尘沉积量变化程度相对较小.     

固定床颗粒层过滤性能分析及预测

使用两种滤料颗粒在一套冷态试验装置上考察了过滤气速和颗粒层厚度对颗粒层过滤性能的影响。结合颗粒层过滤宏观模型,分析了不同操作条件下粉尘比沉积率σ对颗粒层粉尘捕集能力偏离初始值程度F和过滤压降偏离初始值程度G的影响,然后预测了过滤效率和压降。结果表明,试验范围内,随着σ的增大,F呈现先增加后降低的变化趋势,而G逐渐增加。结合过滤气速u=0.2~0.6 m·s^-1、颗粒层厚度L=0.11~0.2 m条件下的试验数据拟合得到了F-σ和G-σ函数关系,过滤效率和压降的计算值与试验吻合较好,优于文献中相关公式,可为颗粒床过滤性能的预测提供参考。     

高压下多管旋风分离器压降模型

为了准确预测和计算天然气输气管线用旋风分离器的压降,在归纳常压下单管和多管旋风分离器的压降计算公式,以及现场测量高压下多管旋风分离器的压降基础上,建立了高压下多管旋风分离器的压降计算模型。利用实验验证压降模型的可靠性,实验结果表明,常压下单管、多管旋风分离器和高压下多管旋风分离器的压降计算模型都能准确地计算出对应旋风分离器的压降值,计算值与测量值之间的误差较小。因此,利用建立的高压下多管旋风分离器压降计算模型能够准确地计算出不同压力和温度下多管旋风分离器的压降值,从而为天然气用旋风分离器的选型提供技术支持。     

颗粒床-旋流耦合分离器不同操作模式下的性能分析

通过实验分别考察了满床/空床操作模式对内置颗粒床-旋流耦合分离器分离性能的影响,获得了两种操作模式下的设备压降和捕集效率。通过改变入口粉尘浓度、入口气速和粉尘颗粒种类,发现满床操作条件下的分离效率比空床操作条件下的分离效率高,且前者压降较低。通过对出口粉尘粒径的分析,含有捕集颗粒的内置颗粒床可有效提高5 μm以下的粉尘颗粒的捕集效率,弥补了离心分离的短板。引入性能指数对不同操作模式进行定量分析,验证了满床操作条件下的耦合分离设备具有更好的综合分离性能。     

Surface-collection efficiency of Nuclepore filters for nanoparticles

The flat surface of Nuclepore filters is suitable for observing collected particles with a scanning electron microscope (SEM). However, experimental data on surface-collection efficiency are limited because surface-collection efficiencies cannot be measured directly using aerosol measuring instruments. In this study, the surface-collection efficiencies of Nuclepore filters were determined by establishing the ratio of the number of particles deposited on the surface of the filter visually counted with an SEM to the number of inflow particles counted by a condensation particle counter, using monodispersed polystyrene latex particles (30–800 nm) and silver particles (15–30 nm). Because Nuclepore filters with smaller pore sizes would be expected to produce higher minimum surface-collection efficiency and a higher pressure-drop, 0.08 and 0.2 µm Nuclepore filters were chosen as the test filters in view of both collection efficiency and pressure drop. The results showed that the minimum surface-collection efficiencies of the 0.08 µm pores at face velocities of 1.9 and 8.4 cm·s^?1 were approximately 0.6 and 0.7, respectively, and those of the 0.2 µm pores at face velocities of 1.5 and 8.6 cm·s^?1 were approximately 0.8 and 0.6, respectively. Because the pressure drop of the 0.2 µm pore filter was lower than that of the 0.08 µm pore filter under the same flow-rate conditions, the 0.2 µm pore filter would be more suitable considering the pressure drop and collection efficiency. The obtained surface collection efficiencies were quantitatively inconsistent with theoretical surface-collection efficiencies calculated using conventional theoretical models developed to determine the collection efficiency of filters with larger pores.

© 2016 American Association for Aerosol Research     

Determination of the Fractional Efficiencies of Fibrous Filter Media By Optical In Situ Measurements

ABSTRACT

An experimental setup is introduced to determine the fractional efficiency of fibrous filters. The device includes two optical particle counters for the in situ measurement of the particle flux and size upstream and downstream of a test filter. The simultaneous measurement in the raw and clean gas by a counting method allows a rapid determination of the fractional efficiencies of various filter media within a few minutes. In the first experiments performed with different aerosols (latex spheres, bacterial aerosol, limestone dust) the apparatus proved to be a reliable instrument for the investigation of the collection behaviour of fibrous filters influenced by various parameters.

The fractional efficiency yields more information about the filter performance, i.e., respirable fraction, collection minimum, particle bouncing off etc., than the total collection efficiency. Thus it is possible to compare different filter media of the same or different filter class and determine their optimum operational conditions.     

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     

A case study of simulating submicron aerosol filtration via lightweight spun-bonded filter media

The most common method of filtration is via fibrous nonwoven media. Fibrous filters are generally characterized by their collection efficiency and pressure drop. Traditional computational studies in this area are typically based on unrealistic 2-D geometries with the fibers simply placed in a lattice (regular array) perpendicular to the flow. The traditional approaches however, do not permit studying the relation between the 3-D structure of a filter media and its performance. In this study, for the first time, a virtual 3-D web is generated based on the fiber orientation information obtained from analyzing microscopic images of lightweight spun-bonded filter media. Pressure drop and collection efficiency of our virtual filter are simulated and compared with the previous 2-D analytical and numerical models as well as experiment. Our pressure drop calculation, unlike the previous models, showed a perfect agreement with the predictions of the Davies’ empirical equation. The collection efficiencies obtained from simulating a thin spun-bonded filter media challenged with submicron particles having diameters ranging from 50 to 500 nm showed a similar trend as that of the previous 2-D models. For the solid volume fraction (SVF), filter thickness, and the fiber and particle diameters considered in this study, we found collection efficiencies higher than that of the above mentioned 2-D models with a relatively good agreement with experimental data obtained from a TSI 8130 filter tester.     

天然气净化用多管旋风分离器的分离性能

为了系统评价天然气净化用多管旋风分离器的分离性能,在线测量了入口气速6~24 m/s、入口颗粒浓度30~2000 mg/m3范围内多管旋风分离器的分离效率和分级效率. 结果表明,多管旋风分离器的分离效率和分级效率都随入口气速和入口颗粒浓度增大而提高. 与单管旋风分离器相比,在相同实验条件下,多管旋风分离器的分离效率下降2%~15%;单管旋风分离器基本能除净粒径大于10 mm的颗粒,而多管旋风分离器只能去除15 mm以上的颗粒. 多管旋风分离器的压降主要是内部单管旋风分离器的压降,占整个压降的80%~90%.     

环流预汽提组合旋流快分系统分离性能的实验研究

针对新型旋流快分器与密相环流预汽提器的优良特性,将两者耦合成一套完整的快分系统. 通过大型冷模实验,研究了该快分系统的分离特性,并考察了操作条件对系统快分效率及快分压降的影响规律. 结果表明,该系统能较好地实现气固高效分离,具有较大的操作弹性和优良的操作稳定性,冷态下分离效率在98.5%以上,最高可达99.93%,快分压降分布合理. 根据实验结果,得到该系统分离效率及压降的经验模型,计算值与实验值吻合较好.     

Retracted: Effects of the Operating Conditions and Geometry Parameter on the Filtration Performance of the Fibrous Filter

The gas‐solid two‐phase flows in fibrous filters were simulated by computational fluid dynamics (CFD) technology. The pressure drops and filter efficiencies with different operating conditions and geometry parameter, including face velocity, particle size, and solid volume fraction (SVF) were calculated. The effects of the operating conditions and geometry parameter on the filter performance of the fibrous filter were obtained. The results indicate that the pressure drop increases linearly with the face velocity and the predicted values of the pressure drops are in excellent agreement with the experimental correlation. Filtration efficiency decreases with the face velocity for submicrometer particles (0.1 μm) and, for larger particles (1 μm) the tendency is just the opposite. The filtration mechanism is different for different particle sizes. For the filter in this paper, when the particle size is smaller than 0.2 μm, Brownian diffusion plays a significant role in the filtration process. When the particle size is greater than 0.5 μm, inertial impaction becomes an important capture mechanism. For particle sizes in the range of 0.2–0.5 μm, the Brownian diffusion and inertial impaction are both relatively weak and, therefore, the filtration efficiency has the least value in this range. Additionally, the SVF distribution is an important geometry parameter in the filter. The filtration efficiency of the filter with a decreased SVF (geometry B) along the thickness of the filter is higher than that of the filter with the even SVF (geometry A), while maintaining a low pressure drop.     

双循环旋风分离器阻力性能的实验研究

双循环旋风分离器通过将主进气口设于简体中部,将顶部进气口设为回流口,消除了传统旋风分离器顶部进气口存在的二次流和短路流,进而使大于3μm颗粒的分离效率接近100%.基于工程设计理论的需求,研究了该新设备的阻力性能.利用直径为0.250 m的实验设备,测定了其压降与进口气速的关系,考察了不同结构和操作条件对其阻力性能的影...