基于超细纳米纤维高效低阻复合滤材的制备及性能研究

以湿法无纺布为支撑层、纺粘无纺布为保护层,熔喷静电棉/纳米纤维/超细纳米纤维为核心过滤层,制备出一种具有多级梯度过滤的复合滤材,并讨论了不同选材和工艺参数对滤材性能的影响。SEM分析表明,该滤材呈现明显的梯度尺度结构。过滤测试结果表明,该滤材初始过滤效率达99.65%,且去除静电后仍能保持在90%以上,而滤阻仅有15.7Pa。与传统熔喷滤材相比,该产品显示出优异的高效低阻性能,而且不受静电衰减的影响,大大增加了滤材使用寿命,在空气过滤领域具有广阔的应用前景。     

纳米粒子气溶胶分析系统的建立

纳米粒子气溶胶分析系统对粒径测量的量值可溯源到标准粒子,可进行单分散、多分散样品的测量以及电子分级筛选。该文介绍纳米粒子气溶胶分析系统的基本原理、测量方法和系统组成,总结了所进行的实验研究。并展望了良好的应用前景。     

金属橡胶滤材过滤精度研究

金属橡胶是一种均质弹性的多孔功能材料,本身所具有的诸多特性使其特别适合于作为滤材。过滤精度是滤材的一项关键性能,是滤材分级和使用的依据,因此有必要对金属橡胶滤材过滤精度及其影响因素进行研究。对金属橡胶孔隙结构一定合理的简化基础上,引入毛细管束模型,推导出金属橡胶滤材水力直径公式,利用多次通过试验法建立金属橡胶过滤精度与其水力直径的关系,通过对实验数据的分析建立金属橡胶滤材过滤精度公式。结果表明该表达式准确地反映出金属橡胶滤材过滤精度的影响因素及其相互关系,为设计金属橡胶过滤器提供可靠的理论依据。     

金属橡胶组合滤材过滤性能实验研究

理想的液固相过滤材料应该是由多种不同过滤特性的材料组合而成,这种滤材能够最大程度地发挥滤材截留悬浮颗粒的能力,延长过滤材料的使用寿命。金属橡胶作为一种新型弹性多孔功能材料,自身诸多的性能优点使其适合制备各种过滤器。采用国际标准ISO16889-1999评定滤芯过滤性能的多次通过方法,详细研究和对比不同结构参数的金属橡胶组合滤材与整体式金属橡胶滤材的过滤性能。研究结果表明,由不同结构参数构成的金属橡胶组合滤材具有更加优异的过滤特性,在过滤效率相同的情况下,组合金属橡胶滤材过滤压降较低,流体的通过性能更好,在达到极限压降前能够容纳更多的污染物,滤材使用寿命大为延长,过滤性能得到充分的发挥。     

玄武岩纤维生态环境复合滤材过滤性能的研究

讨论了玄武岩纤维复合过滤性能和微孔尺寸,打浆度、玄武岩纤维含量等因素的相互关系.结果表明,滤材的平均孔径与其含量能呈很好的相关性.通过扫描电镜观察,提出了复合滤材的结构模型.不同打浆度和玄武岩纤维含量下,孔径与过滤速度的关系研究表明,最小、最大和平均孔径与过滤速度的变化趋势是一致的.复合滤材的过滤速率随孔径的降低而变小,孔径降低到一定的程度后,过滤速率降低缓慢.同时分析了颗粒在介质上的滞留方式导致过滤性能下降的原因.复合过滤材料的热性能研究表明,过滤性能的破坏主要是由木纤维的热老化造成的.     

新型金属纤维滤材的除湿性能

以不同丝径的不锈钢纤维为金属纤维过滤器的滤材,通过实验分析滤层厚度对纤维过滤器的除湿性能的影响。结果表明,增加滤层厚度可以有效提高除湿效率,但当8μm纤维滤层超过6层后,滤层除湿效率变化不大;实验结果与经典过滤机理模型计算值的相对误差小于9%,经典过滤机理模型可用来预测新型不锈钢纤维过滤器的除湿效率。     

纳米气溶胶的净化技术

针对目前人工纳米材料的广泛应用而造成大量的纳米气溶胶颗粒进入大气中危害环境及人类的健康的问题,本文中论述了纳米气溶胶的性质及其分类,根据国内外文献的报道,分析了纳米气溶胶净化技术的研究现状及影响因素,提出凝并技术与过滤净化技术相结合将是纳米气溶胶净化技术的发展趋势,并提供了具体方案,为纳米气溶胶净化工艺的选择提供了指导性参考。     

微纳米纤维空气净化滤膜的研究进展

微纳米纤维由于比表面积高、长径比高和孔隙率高等优点在制备空气净化滤膜方面极具应用潜力,但始终面临高的过滤效率和低过滤阻力之间的矛盾.文中首先介绍了不同材料制备的微纳米纤维膜的过滤性能,并对不同材料的特性和过滤效果进行了分析;其次总结了典型的微纳米纤维膜结构,包括纤维形貌、纤维膜内结构和层间结构;最后对高效低阻微纳米空气...     

静电纺纳米纤维用于过滤介质的研究现状

静电纺丝技术能便捷地制备连续性纳米纤维,为高效过滤提供了新的过滤介质.介绍了静电纺纳米纤维用于过滤介质所需要的结构与性能的表征,详细总结了静电纺纳米纤维用于液体过滤和气体过滤的研究现状,并在此基础上展望了静电纺纳米纤维用于过滤介质的开发趋势.     

粉体气溶胶旋流生成效率的试验研究

针对一种3级旋流-粉体气溶胶发生装置,测试分析旋流生成气溶胶的粒谱分布特征,由此定义气溶胶旋流生成效率;研究气流压力、脉冲时间、粉体装填量、旋流喷嘴结构等参数对生成效率的影响。结果表明,旋流装置对粒径为1~10μm的超细粉体能达到很高的气动分散效率;在较小的气流压力下,旋流装置仍能获得很高的气溶胶生成效率;适当减小粉体装填量,可改善气溶胶的生成效果;进气角度、出口锥角分别为15、45°时,气溶胶生成效率最高。     

纤维过滤器过滤理论的研究进展

评述了近几年来国内外的纤维过滤理论与技术的研究及发展状况,讨论气体过滤基本机理,给出了捕集效率和压力降理论计算公式最新研究成果,指出了纤维过滤理论需进一步研究解决的问题。     

静电增强纤维动态过滤的理论研究

为了推导、预测滤料间有外加静电场时过滤器效率和压降的变化并且分析各参数如纤维厚度、颗粒直径、电场强度对效率和阻力的影响,提出了建立在D．Thorns建立的数学模型的基础上的静电增强纤维动态过滤效率和压降的计算方法,首先计算了单纤维的过滤效率和压降,然后计算纤维过滤器稳定状态的过滤效率和压降,从而计算了纤维过滤器动态过滤时的效率和压降,得出了重要结论：粒子直径越小,压力损失越大；电场强度越大,过滤效率越大,压力损失越小；增加纤维厚度能显著提高过滤器的过滤效率。     

羊毛滤料对颗粒物的过滤机理及其过滤效率的影响因素分析

针对羊毛纤维过滤材料对大气尘中颗粒物的过滤机理进行了理论分析,研究了羊毛纤维过滤材料对颗粒物的过滤效率的影响因素,并结合羊毛纤维的特殊优势,进一步探讨以羊毛纤维为基材的过滤材料净化室内空气的相关机理及其应用。     

粉尘对空气滤清器原始过滤效率测试结果的影响

为了比较国内外不同试验粉尘对空气滤清器原始过滤效率测试结果的影响,说明试验粉尘对于过滤效率测试的重要性,对国内外标准所规定的试验粉尘的粒径分布和形貌特征进行测试分析。结果表明:在相同实验条件下,以石英砂作为试验粉尘测得的原始过滤效率为99.35%,以A2细灰作为试验粉尘测得结果为99.10%;从粉尘粒径分布和形貌特征两方面讨论造成原始过滤效率测试结果不一致的原因。     

A Simplified Model to Estimate the Size Distribution Change of Polydispersed Aerosol for Cyclone Separator

ABSTRACT

Although the air-lift pump has been superseded by submersible pumps in raising water from wells and mines, it still provides an attractive means of lifting abrasive slurries because, unlike mechanical pumps, it has no moving parts to wear. However, current design of air-lift pumps must rely on empirical equations, or, at best, incremental computer solutions. Design is complicated by the fact that relative velocities of the phases change over the whole pump length. A new design equation is developed to predict the lift of an air-lift pump, given the flowrates of air, liquid and solid in the pump, and the dimensions of the air-lift tube. The new equation is baaed on well-established multiphase flow theory, and offers significant advantages over current design techniques. In combination with an equation for the overall pump efficiency, the new equation provides a method for optimizing the design parameters for the air-lift pump.     

Observation Evaluation of Nozzle Clogging in a Micro-orifice Impactor Used for Atmospheric Aerosol Sampling

A micro-orifice impactor uses micro-orifice nozzles to extend the cut sizes of the lower stages to as small as 0.18 μm in diameter without resorting to low pressures or creating excessive pressure drops across the impactor stages. In this work, the phenomenon of nozzle clogging caused by particle deposition was investigated experimentally for a commercial micro-orifice uniform deposit impactor (MOUDI, MSP model 100). Using an optical microscope, we observed that the micro-orifice nozzles of the lower three stages were partially clogged due to particle deposition during the atmospheric aerosol sampling. To examine the effect of nozzle clogging on the performance of the impactor, the pressure drop and the particle collection efficiency were evaluated for the lower three stages. The pressure drops across the clogged nozzles were higher than the nominal values given by the manufacturer. The particle collection efficiency of each stage was evaluated by using an electrical method for fine particles with diameters in the range of 0.1-0.6 μm. Monodisperse liquid dioctyl sebacate (DOS) particles were used as test aerosols. A Faraday cage was employed to measure the low-level current of the charged particles upstream and downstream of each stage. The collection efficiency curves shifted to correspondence to smaller orifice sizes, and the 50% cutoff sizes were much smaller than those given by the manufacturer for the three stages with nozzles less than 400 μm in diameter.     

植栽对钢铁厂空气中微粒物质及SO_2净化效能评估

探讨了钢铁厂绿化植栽对空气中微粒物质及SO2的净化效果,选取19种常见绿化树种进行评估。在钢铁厂高炉作业区及污染较低的学校区分别置放试验树种,试验共为期16个月,试验结束后,通过叶片累积微粒物质含量分析其拦截粒状物效能;而通过叶片内含硫量分析推估对空气中SO2的净化效益。结果显示,对大气中微粒净化效能以兰屿肉豆蔻最佳,净化量为29.1g/m2;其次为稜果榕与海芒果,净化量分别24.2、17.4g/m2。试验树种吸收大气中SO2以竹柏、稜果榕及兰屿肉豆蔻较佳,单位质量叶片去除SO2量分别为0.92、0.9、0.8mg。     

卷包机组设备效率评价指标体系的设计与实现

目的 针对烟草行业常见设备卷包机组,提出一种结合OEE的设备效率评价体系,实现对卷包机组设备运行状态的精确、实时、具体的反映.方法 通过分析离散制造与连续制造的差异,在传统离散制造OEE方法基础上,针对连续生产进行适应性改进,提出一套针对卷包机组的设备效率评价指标;在此基础上,通过分析卷包机组各运行单元结构特点,提出一套实时采集设备状态数据与动态分析效率状态的卷包机组设备效率评价体系.结果 将此体系部署于湖北中烟某车间6台卷包机上6个月进行实验验证,结果显示在该体系的支持下,设备净效能平均同比增长7.72％,证明本效率评价结果可以精准、全面、实时地反映设备运行情况和状态背后的影响因素,有助于提升卷烟机组设备效率.结论 文中提出的卷包机组设备效率评价指标体系使用户可以针对性、快速地调整设备运行状态,实现了精准管理,提高了生产作业效率,具有实际的推广价值.     

Structure optimization of granular bed filter for industrial flue gas filtration containing coagulative particles: An experimental and numerical study

A numerical model for the flow and filtration characteristics of industrial flue gas in granular bed filter (GBF) was established and the local filtration efficiency for different granule layers was investigated. Numerical validation results show that the GBF structure with large size granules at the inlet region and small size granules at the outlet region can effectively improve the filtration performance of GBF and the underlying mechanism was revealed. Then an experimental system was built to validate the suitability of the optimized GBF structure for the filtration of industrial flue gas with coagulative particles. The experimental results show that the optimized GBF structure is also suitable and its superiority is more significant with the increase of filtration time. The results show that the pressure drop and filtration efficiency of the experimental system increase with the increase of dust particles concentration. The existing of coagulative particles is conducive to the growth of smaller size dust particles, the pressure drop and filtration efficiency increase significantly. In addition, the pressure drop and filtration efficiency decrease with the increase of cooling rate. The results of this study are expected to be useful for the design and optimization of industrial flue gas purification and waste heat recovery.     

Analysis of the performance of a sintered stainless steel wire mesh filter for cryogenic liquid purification

As a traditional and mature solid-liquid separating technique, filtration has been adopted in cryogenic liquid purification system owing to its low energy cost, simplified system, long lifetime and high purifying efficiency. Whereas, few data or result of filtration performance at low temperature is put forward in literatures, most of which are related to room and high temperatures applications. Furthermore, as an excellent cryogenic material, stainless steel medium is suitable for cryogenic liquid filtration, which is also seldom reported. In this paper, we propose a filtration system for purifying CO₂ particles from liquid nitrogen using a sintered stainless steel wire mesh filter with a nominal filtration degree of 0.5 μm, and characterize the separation behavior of this kind of filter medium at cryogenic temperature. Experimental results show that the whole filtration process can be divided into three stages with sufficient particle concentration in the feed slurry according to the evolution of pressure drop. Differences between surface filtration and depth filtration are demonstrated, and the influence of growth of filter cake is characterized. Pressure drop increases with increasing feed slurry flow and CO₂ concentration, and evolution tendency of filtration efficiency is affected by its calculation method. By comparison with the filtration at room and high temperatures, the effects of temperature on the fluid and media are emphasized.