振筛进料流化床气溶胶发生器性能的初步研究

为了满足流化床气溶胶发生器中小量均匀的进料要求,本文探索了用振筛机作为动力的进料器,并对发生器产生的气溶胶进行了测试.结果表明,发生器可以产生浓度和粒度分布比较稳定的气溶胶.同时还发现发生器的流量在一定范围内可用于调节气溶胶浓度,而粒度分布基本不变.     

含油污水旋流分离器性能研究

对油水分离用水力旋流分离器的分离性能和压力降进行了实验研究,分别考察了进料流量,进料含油量,油滴聚结器对分离效率的影响.同时,考察了进料流量,溢流比,溢流管直径对旋流分离器的压力降的影响.     

溶液浓度和载气流量对气溶胶特性的影响

随着PM 2.5成为热点,PM 2.5口罩的测试手段也开始受到广泛关注,气溶胶粒子浓度及粒径分布则是口罩过滤效果测试中最重要的参数。为了使测试条件更为贴近口罩的实际工况,针对口罩测试中常用的NaCl固体气溶胶和DEHS油性气溶胶,探讨了气溶胶发生器的溶液浓度和载气流量对气溶胶粒子计数浓度及粒径大小特性的影响。结果表明,溶液浓度和载气流量对气溶胶粒子计数浓度有明显影响;NaCl溶液浓度对气溶胶的粒径大小有影响;载气流量对NaCl气溶胶的粒径大小无明显影响,而对DEHS气溶胶粒径大小有影响。     

生物质快速热解流化床反应器气力进料特性

为探究不同工况下热解流化床反应器的气力进料特性,设计并搭建了流化床反应器气力进料冷态试验装置。生物质原料和床料分别采用落叶松颗粒和石英砂颗粒,通过试验测得了本装置的最小流化速度,研究了流化气速、喷动气速、流量比、初始静床高、石英砂粒径、落叶松粒径对流化床反应器气力进料特性的影响。试验结果表明：流化气速和喷动气速的增加均会提高进料率;流化气使床料流化并为落叶松颗粒提供进料空间,喷动气为落叶松颗粒提供动能,并平衡一部分床层压力;落叶松与石英砂粒径的增加对进料效果不利;流量比在1.9~2.7范围内进料率高且稳定性好。本文构建了生物质、床料与气体的三相流物理及数学模型,开展试验对模型进行验证,结果表明其预测误差为±13%。     

新型提升管进料段内压力脉动强度分布的影响因素

通过大型冷模实验,考察了油剂逆流接触提升管进料段内压力脉动强度的轴、径向分布,并结合射流气浓度分布、预提升气浓度分布和颗粒浓度分布分析了气固间作用特征及其对流动的影响. 结果表明,根据喷嘴射流、预提升气及颗粒相对压力脉动的贡献,可将新型提升管进料段沿轴向由下而上分为喷嘴进气上游影响区(H=?0.375~?0.1 m)、喷嘴进气控制区(H=?0.1~0.375 m)及喷嘴进气下游影响区(H=0.375~0.675 m). 进料段内压力脉动相对标准偏差径向分布的模拟值与实验值吻合较好.     

不同原理的雾化器对农药非均相液体制剂发生效果的比较评价

[目的]探讨2种不同原理的雾化器对非均相液体制剂气溶胶发生效果的比较评价,为非均相液体制剂吸入毒理试验发生器的选择提供依据。[方法]选取非均相液体制剂70个,依据不同原理的雾化器分为A组(使用压缩空气原理进行雾化)和B组(使用超声波二相流重力预筛选重复阵式温控原理进行雾化),同时对气溶胶浓度及粒径进行统计分析。比较2组不同原理的雾化器对非均相液体制剂气溶胶发生的浓度、质量中值空气动力学直径(MMAD)及几何标准差(GSD)的结果。[结果]通过SPSS软件单因素方差进行统计分析。2组对非均相液体制剂气溶胶发生的MMAD及GSD相比较,效果一致,都满足MMAD在1～4μm之间,GSD在1.5～3.0之间。差异无统计学意义(P0.05)。但是在气溶胶发生浓度方面,B组明显高于A组,差异有统计学意义(P0.05)。[结论]使用超声波二相流重力预筛选重复阵式温控原理的雾化器在对相同状态的非均相液体制剂、同样的控制系统、同样的进气流量及同样品质量的前提下,发生的气溶胶浓度明显高于使用压缩空气雾化器。     

混合胺修饰的介孔硅胶吸附CO2性能研究

以介孔硅胶为载体,采用"嫁接+浸渍"两步法制备了混合胺(APTS+TEPA)修饰的介孔硅胶吸附剂。在固定床中考察了3-氨丙基三乙氧基硅烷(APTS)和四乙烯五胺(TEPA)负载量、吸附温度、进气流量对CO2吸附性能的影响,并研究了吸附剂的循环稳定性。结果表明,当APTS负载量30%,TEPA负载量30%(TEPA30-APTS30-MSG),吸附温度为70℃,进气流量为30 m L/min时,该吸附剂表现出最好的吸附性能,饱和吸附量高达3.04 mmol/g,较纯TEPA浸渍提高了37.6%。该吸附剂经10次吸脱附循环后,饱和吸附量仅下降2.96%,具有较好的循环稳定性。     

纳滤膜技术浓缩分离含镍离子溶液

采用纳滤膜法对较高浓度含Ni2+离子溶液进行了高倍数浓缩,考察了操作压力、进料液流量、原水Ni2+离子质量浓度和pH等因素对分离过程性能的影响.结果表明,纳滤膜对Ni2+的截留率随操作压力、进料液流量和原水Ni2+质量浓度的增加而增大,膜通量则随进水Ni2+的质量浓度增加而减小.对于Ni2+质量浓度为3900 mg·L-1,pH为3的NiSO4溶液原水,在操作压力1.4MPa条件下,经截留液全循环工艺运行,纳滤淡化出水Ni2+的截留率均保持在99.6%以上,浓缩液中Ni2+质量浓度最高可能达到23 510mg·L-1,浓缩倍数超过6.研究表明,选择适宜的纳滤膜用于重金属废水的高倍数浓缩,实现有价金属的资源化回收具有良好的技术可行性.     

均四甲苯气相浓度调控仪的研制

利用自制的高熔点物料气相浓度调控仪,研究了均四甲苯溶液的温度、导气管管口距离均四甲苯液面的高度、空气进气温度和进料量等对均四甲苯气相浓度的影响。实验结果表明：均四甲苯溶液的温度、空气进料量对均四甲苯气相浓度影响较大,而导入管距离液面的高度和空气温度影响较小。自制的高熔点物料气相浓度调控仪能很好地调控气相中均四甲苯的浓度,具有推广应用价值。     

纳滤技术回收乳制品废水中乳糖的研究

以回收乳制品废水中的乳糖和再生废水为目的,研究了纳滤膜法回收废水中乳糖的工艺,系统地讨论了操作压力、进料流量、浓缩比等因素对回收率和对COD去除率的影响。在本实验条件下,纳滤膜法回收乳制品废水中乳糖的最佳操作压力为1.0 MPa,进料流量为28 L/min。在此最佳操作压力和进料流量下,废水中乳糖的回收率为100%。而纳滤膜处理后乳制品废水的各项水质指标也达到了再生水的水质标准。     

Design and Characterization of a Fluidized Bed Aerosol Generator: A Source for Dry,Submicrometer Aerosol

A fluidized bed aerosol generator has been designed and built for the purpose of generating a constant output of dry, submicrometer particles with a large number density. The output of the fluidized bed for generating aerosol particles from dry soot powder has been characterized using a differential mobility analyzer and a condensation particle counter. The particle size distribution is bimodal, with a mode in the submicrometer diameter size range and a mode in the supermicrometer diameter size range. The larger diameter mode is fully separated from the smaller mode and can thus be easily removed from the aerosol flow using impaction techniques. The distribution in the submicrometer size range is nearly log-normal, with a count median diameter falling between 0.1 and 0.3 micrometers. A number density of greater than 10⁵ particles cm^-3 of soot particles in the submicrometer range can be produced, constant to within 25% (1 standard deviation) over a 4 h time period. The number density of particles produced in the submicrometer range was found to vary with the ratio of soot to bronze beads in the bed mixture, whether or not a feed system was used, and nitrogen flow rate through the fluidized bed and feed system.     

Monodisperse fine aerosol generation using fluidized bed

Monodisperse, fine aerosols are needed in many applications: filter testing, experiments for testing models, and aerosol instrument calibration, among others. Usually, monodisperse fine aerosols are generated in very low concentrations, or mass flow rates, in the laboratory scale. In this work, we needed to generate aerosols with higher mass flow rate than typically available by the laboratory-scale methods, such as atomizers, nebulizers, ultrasonic generators, vibrating orifice generators, and condensation generators. Therefore, we constructed a fluidized bed aerosol generator to achieve particle mass flow rates in the range of 15-100 g/h. Monodisperse, spherical SiO₂ particles of two sizes with geometrical diameters of 1.0 and 2.6 µm were used in the aerosol generator. The aerosol generator was used at both atmospheric pressure, and at high pressures up to 5 bar (abs).The particle size, mass concentration and the net average particle charge were measured after mixing the aerosol with nitrogen. The particle size distributions with both particle sizes were monodisperse, and no particle agglomerates were entrained from the fluidized bed. The behavior of the fluidized bed generator was found to be markedly different with the two particle sizes in regard to particle concentration, presumably due to different particle charging inside the generator. After determining the net average charge of the particles, an ion source Kr-85 was used to reduce the charge of the particles. This was found to be effective in neutralizing the particles.     

Electric field phenomena in fluidized and fixed beds

Stabilization of a bed of dielectric particles against fluidization by an electric field (≥ 10³ volts/cm) is described. Glass bead and silica gel particle beds have been observed to behave as packed beds with flow rates (and pressure drops) of the fluidizing gas up to 15 times the normal incipient fluidization rate. The pressure drop at the breakup of this fixed bed was dependent on the second power of voltage, the particular bed material, and geometry of the system. Under suitable conditions 100% bed expansion without diffusive particle motion or bubble formation was obtained using silica gel particles. Comparison with iron particle bed-magnetic field effects are presented. Surface polarization charge effects are the simplest explanation of the phenomena. Several of the possible applications are suggested, such as precipitation enhancement in an aerosol filter or as a new tool for investigating aggregative fluidization.     

Fluidized Bed Generation of Stable Silica Nanoparticle Aerosols

A long-lasting generator of continuous silica nanoparticle aerosols based in a fluidized bed of glass beads coated with nanosized silica has been developed. The attrition resulting from the bubbling fluidized bed regime progressively detaches the silica coating from the glass beads, giving rise to a steady production of silica nanosized aerosols with median diameters from 100 to 250 nm depending on the initial size of the coating nanoparticles. Continuous aerosol production could be maintained for more than 12 h, and the nanoparticle concentration can be easily tuned in the range of 2000 to 14,000 #/cm³ by adjusting the fluidization and/or dilution flow rates.

Copyright 2013 American Association for Aerosol Research     

含内构件的循环流化床的动态压力特性

针对含内构件的循环流化床,以石英砂为物料,使用动态压力传感器测量了含内构件的流化床中气固两相流的动态压力,分析了床内的瞬时压力特性. 结果表明,在进出口总压降中,文丘里压降最大,占主床压降的60%以上. 表观气速和固体颗粒循环流率共同影响循环流化床内的压力特性. 压力瞬时波动功率谱分析表明,压力波动对应一个主频,表观气速越小、颗粒循环流率越大时,压力波动越大,且循环流化床底部压力波动比上部大. 加入内构件能有效引导气流,使流动更均匀.     

几种典型铁矿粉的流化特性

利用内径150 mm的D型有机玻璃流化床模型,对澳矿、巴西矿、北方矿和钒钛矿典型铁矿粉的流化特性进行了实验研究,获得了其流化特性曲线、初始流化速度和最大床层压降,并将初始流化速度的实测值和理论计算值进行了比较分析. 结果表明,矿粉粒度是影响其流化特性的最主要因素,粒径越大,床层所需要的初始流化速度越大,实测值和理论估算值基本相符;粒度小于0.125 mm钒钛矿流动性较差,在流化过程中易出现沟流现象;粒度范围较宽的矿粉,完全流态化时,细矿粉随气流夹带逸出明显;在粒度相同的情况下,几种不同的铁矿粉的开始流化速度接近,而床层压降有较大差异,巴西矿的床层压降明显大于其他三种铁矿粉. 最大床层压降的最小值均出现在粒度为0.25~0.425 mm,为铁矿粉流态化还原过程中较适宜的粒度范围.     

Removal of emulsified oil from water by inverse fluidization of hydrophobic aerogels

Different size ranges of surface-treated hydrophobic silica aerogels (Nanogel^®) provided by Cabot Corporation are fluidized by a downward flow of an oil-in-water emulsion in an inverse fluidization mode. Surface areas, pore size distributions, and pore diameters are investigated by using BET and contact angle is measured by a goniometer. The hydrodynamics characteristics of the Nanogel granules of different size ranges are studied by measuring the pressure drop and bed expansion as a function of superficial water velocity. The density of the Nanogel granules is calculated from the plateau pressure drop after the bed is fully fluidized. The oil removal efficiency of a dilute (1000 ppm COD or lower), stabilized (using the emulsifier Tween 80) oil-in-water emulsion and the capacity of the Nanogel granules in the inverse fluidized bed are also studied. A model was developed to predict the inverse fluidized bed experimental results based on equilibrium and kinetic batch measurements of the Nanogel granules and the stabilized oil-in-water emulsion. The results show that the major factors which affect the oil removal efficiency and capacity are the size of the nanogel granules, bed height, fluid superficial velocity and the proportion of emulsifier in the oil-in-water emulsion. The Nanogel particles can absorb as much as 2.8 times their weight of oil by the inverse fluidization process.     

Effect of solid circulation rate on coating efficiency and agglomeration in circulating fluidized bed type coater

Circulating fluidized bed was proposed to be used as a coater, and coating experiments of glass beads with silica powder were performed in a circulating fluidized bed. Glass beads and silica powder were chosen as model particles, because their shape was almost spherical. The respective effects of gas flow rates supplied from a distributor and from an air nozzle for solid circulation, feed rate of powder suspension and particle content in the bed on coating efficiency and agglomeration are mainly discussed. Coating efficiency in circulating fluidized bed coater was correlated well with solid circulation time rather than with gas flow rates or solid circulation rate, while the agglomeration among core particles was mainly governed by solid circulation rate.     

Particle characteristics of a stable fluidized bed aerosol generator

An aerosol generator consisting of a vibrating system for feeding dust into a fluidized bed was developed and tested to determine its dust output characteristics. The dust feed unit can produce 0–40 g min⁻¹ of coal dust and shows constant output up to 3 h operation durations. These correspond to mass concentrations of 0–101 g m⁻³ of coal particles for an air flowrate of 395 l min⁻¹ through the aerosol generator. The aerosolized coal particles show constant particle size distribution with time for up to h of testing under varied operation parameters. The normalized particle size distribution remains almost identical for a given feed material for a range of dust loadings. The time required to reach steady state aerosol generation is negligible for the sizes of coal particles used in this investigation.     

流化床管式分布器内流场模拟和布气性能分析

以催化裂化装置（FCCU）再生器的管式气体分布器为研究对象,对流化床管式气体分布器的布气性能进行了分析。首先,对气体分布器分支管内的流场进行数值模拟,计算结果表明沿分支管内气体流动方向,压力逐渐增大,截面流量逐渐减少,沿程喷嘴流量逐渐增大;同时分支管上游入口还存在着明显的偏流现象,从而导致了上游喷嘴的出口流量小于设计流量,下游喷嘴的出口流量高于设计流量,造成流化床内非均匀布气。然后,依据分支管的变质量流动特点,将一般变质量流动的动量方程用于分析分支管内的流动过程,表明分支管的流动过程属于“动量交换控制模型”,具有始端静压低末端静压高的特点,固有压力分布不均匀的特征。这种不均匀的压力分布导致了喷嘴布气不均匀和磨损等系列问题。最后,结合流化床内的压力特点,综合分析气体分布器的分支管压降和喷嘴压降,明确了喷嘴出口流量与分支管压力分布的关系,喷嘴临界压降与设计压降的关系,结论表明分支管的结构改进可以优化和改善分布器的布气性能。