亲水改性碳钢极板用于PM2.5脱除

火电厂大气污染物排放标准日趋严格,湿式静电除尘器作为终端治理设备逐渐得到广泛应用。以亲水改性刚性极板为研究对象,建立了卧式湿式静电除尘器中试实验台,开展了PM_2.5脱除特性的实验研究,研究了改性极板表面水膜增强颗粒物脱除效率的机制,考察了气体温度、停留时间、工作电压、初始浓度、冲洗水流量等主要运行参数对颗粒物脱除效率的影响规律。结果表明：改性刚性极板表面的纤维层可以减少反冲气流,减少颗粒的电迁移阻力;表面在小水量情况下亦可维持均匀稳定的水膜,水膜的存在抑制了反电晕和二次扬尘的发生,使得电晕电流高且水膜蒸发使烟气湿度提高,颗粒荷电量和电迁移速度提高,这两方面均提高了颗粒脱除效率。停留时间延长、工作电压提高均会引起颗粒脱除效率的增加,但颗粒物入口浓度、冲洗水流量对颗粒脱除效率影响不大。使用改性刚性极板的湿式静电除尘器可减少阳极冲洗水量,对粒径0.04～0.48 μm的颗粒有较高脱除效率,可在低电压下达到较高的颗粒物总脱除效率,具有较好的应用前景。     

纤维水膜极板表面颗粒沉积脱落特性

以极板表面荷电颗粒电子传递及离子定向迁移为基础,对纤维极板表面沉积颗粒粒径分布、粉尘层堆积形貌、颗粒沉积脱落过程及关键影响因素等进行了研究,并与金属极板进行对比。结果表明：静电场同一位置处（取样点15）,纤维极板表面沉积颗粒物的粒度（6.900 μm）小于金属极板（9.018 μm）,纤维水膜极板对颗粒物的捕集效率更高;与金属极板不同,纤维水膜极板表面粉尘层堆积形貌与电晕电流密度分布无明显关联性。荷电颗粒是以纤维束凸出处为沉积中心,沉积并聚集成球或链珠状,粉尘层厚薄随机且分布松散;纤维极板液体表面浸润和内部扩散,减小了纤维极板表面与粉尘层间静电力,增大了粉尘层内颗粒间黏结力;流动曳力、液桥力、静电力、重力是纤维极板控制粉尘层脱落的关键因素。     

Filtration Characteristics of a Miniature Electrostatic Precipitator

This study investigates the filtration characteristics of a miniature dual saw-like electrodes electrostatic precipitator (ESP). Parameters such as particle size, rate of airflow through the ESP, voltage of charge electrode, and discharge polarity were considered to study their influence on aerosol penetration through the ESP. Polydisperse and monodisperse particles with sizes ranging from 30 nm to 10 w m were used as the challenge aerosols. Experimental results indicated that the aerosol penetration through the ESP decreased (from 96% to 15% for 0.3 w m) as the voltage of the discharge electrode increased (from + 4 kV to +8 kV) at a flow rate of 30 L/min. At a fixed electrode voltage (+8 kV), aerosol penetration increased from 15% to 69% for 0.3 w m particles as the flow rate increased from 30 to 120 L/min. The most penetrating particle size was in the range of 0.25 w m to 0.5 w m depending on the discharge voltage and the flow rate. In general, the most penetrating particle size of the ESP decreased with decreasing discharge voltage or with increasing flow rate. At the same voltage level but opposite polarity, the aerosol penetration through the ESP with negative corona was lower than that with positive corona. The difference in aerosol penetration was a factor of about 2 between the negative and positive coronas for 0.3 w m particles, and this difference was found to be independent of discharge voltage. Regarding energy conservation, use of a negative-polarity ESP was more economical if the same efficiency was required. However, the ozone generated by the ESP with negative polarity was about five times greater than that generated with positive polarity. Therefore when using an ESP as an indoor air cleaner, the search for an optimum balance between ozone production and aerosol collection efficiency should be considered.     

Facing the Sulfuric Acid Aerosol Problem in Flue Gas Cleaning: Pilot Plant Experiments and Simulation

Experimental and simulation results of sulfuric acid aerosol formation during absorption of sulfuric trioxide in a wet flue gas scrubber (quench cooler) are presented. The complete characterization of the volatile aerosol with respect to number concentration and droplet size distribution is only possible by combining experimental and theoretical methods. Both experiments performed in a pilot plant and simulation results, reveal high number concentrations. A simulation tool predicts the formation of very small droplets that remain even submicron after coagulation in typical residence times of scrubbing systems and thus are difficult to precipitate.

Copyright 2013 American Association for Aerosol Research     

Effects of Some Geometric Parameters on the Electrostatic Precipitator Efficiency at Different Operation Indexes

The performance of electrostatic precipitators (ESPs) was usually obtained under different geometric parameter values and operation indexes. Hence different conclusions were made in the literature and similar improvements may not be obtained for other applications. In this paper the effects of some geometric parameters on the performance of a wire-plate ESP at different operation indexes are evaluated theoretically. The geometric design parameters include discharge wire diameter, wire-to-wire distance, and plate-to-platespacing. And the operation indexes considered are the electric field strength, the average current density at plates, and the corona power ratio. The results show that the collection efficiency is increased with a decrease in the wire diameter under the same electric field strength. But opposite results are observed under the same average current density at plates or the same corona power ratio applying to the ESP. The optimal wire-to-wire distance and plate-to-platespacing vary as the electric field strength is changed. On the other hand, high collection efficiencies are always obtained with decreases in the wire-to-wire distance and the plate-to-plate spacing under the same average current density at plates or the same corona power ratio.     

Abscheidung hochohmiger Stäube in einem Elektrofilter mit niederfrequenter Wechselspannung

Due to the occurrence of back corona, the separation of particles with high electrical resistivity in electrostatic precipitators (ESPs) is difficult. In this case, the power consumption of the ESPs is significantly increased, and unacceptably high particulate emissions occur. Here, a novel approach for the separation of highly resistive dusts with ESPs is described. The effective electrical resistance of the dust layer can be modified by the use of low‐frequency AC voltage, which significantly improves the separation rates. The new method was tested with various highly resistive dusts in a wire‐tube ESP.     

Cost-Efficiency Analysis of a Model Wire-Plate Electrostatic Precipitator via DNS Based Eulerian Particle Transport Approach

The object of this work is to outline a methodology that can improve the current procedures used to size cost-optimized, efficient electrostatic precipitators (ESP). Focusing on a model wire-plate ESP initially, we develop a two-dimensional Eulerian, advection-diffusion type model for particle transport with distributed parameters. The Eulerian model is assessed against the accurate Lagrangian particle tracking database obtained for a model ESP using the parameter-free, highly accurate direct numerical simulation database obtained in previous work (Soldati 2000; Soldati and Banerjee 1998). Results show that the simplified Eulerian model can have good performances, provided that the functional form of the required transport parameters (i.e., turbulent dispersion coefficient, electromigration velocity, and convection velocity) are properly defined. Next, the cost function for a model ESP is defined and the influence of several design parameters on cost and collection efficiency is examined to identify guidelines to increase the collection efficiency at the lowest cost. Considering the cost associated with variation of precipitator length and width, wire-to-plate distance, and voltage applied to the wires, results show that the most cost-effective way to increase the collection efficiency of a wire-plate ESP is to decrease the wire-to-wire distance. Furthermore, the reasons for cost effectiveness of wider-spacing ESPs are demonstrated from a theoretical viewpoint, thus confirming the experimental observations of Navarrete et al. (1997).     

Separation Characteristics of Submicron Particles in an Electrostatic Precipitator with Alternating Electric Field Corona Charger

Experiments were carried out to investigate filtration characteristics of an electrostatic precipitator (ESP) with alternating and direct electric field corona charger. Potassium Sodium Tartrate Tetrahydrate as the material was used to generate polydisperse submicron aerosols by using Constant Output Atomizer. The results indicated that the aerosol penetration through the ESP decreased as applied voltage increased. The maximum collection efficiency of either alternating or direct electric field was more than 98%, though the applied voltage of alternating electric field was higher than that of direct electric field. However, from the viewpoint of power consumption, the direct electric field had higher power consumption rate than alternating electric field at similar collection efficiency. For example, when the 0.2 μm particle penetration was about 4%, the power consumptions of alternating and direct electric field were 16 watt and 18 watt, respectively. Hence the separation quality of alternating electric field was better than that of direct electric field. Moreover, considerably lower ozone concentration was found in alternating electric field ESP, compared to direct electric field.     

Developing protective textile materials as barriers to liquid penetration using melt‐electrospinning

Electrospun polypropylene fiber webs and laminates were developed using melt‐electrospinning, to explore an alternative way of manufacturing protective clothing materials for agricultural workers. Electrospun polypropylene webs were fabricated in two levels of thickness. To examine the effect of lamination on the protection/thermal comfort properties, the webs were laminated on nonwoven fabric substrates. Barrier performance was evaluated for the electrospun webs and laminates, using two pesticide mixtures that represent a range of surface tension and viscosity. Effects of web thickness and lamination on air permeability and water vapor transmission were assessed as indications of thermal comfort performance. Penetration testing shows that electrospun polypropylene webs provide excellent barrier performance against the high surface tension challenge liquid, whereas the laminated fabrics of electrospun polypropylene webs exhibited performance of 90–100% for challenge liquids with varying surface tension. Air permeability of electrospun polypropylene webs decreased by ～20% because of the lamination and web thickness, but was still higher than most of the materials currently in use for protective clothing. Water vapor transmission of electrospun polypropylene webs reduced by up to 12% from the lamination and web thickness as well, but was still in a range comparable to woven work clothing fabrics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3430–3437, 2006     

SiO2改性聚丙烯纤维棉对油水乳状液的高效分离

近年来,基于特殊润湿性理论制备表面具有微纳米粗糙结构的多孔材料成为油水分离领域研究的重点。为了满足不同环境下对不同形式油-水乳状液高效高通量分离的需求,该研究利用纳米SiO2颗粒对聚丙烯（PP）纤维棉有针对性地亲（疏）水改性,构建了系列不同润湿性和粗糙度的PP纤维棉,探究了不同孔隙度和表面能的PP纤维棉对W/O及O/W型乳状液的分离性能,结果表明,经过亲（疏）水改性后的PP纤维棉对水/正己烷和水/甲苯乳状液的分离效率都高于99.5%,通量高于700 L/(m2·h),并针对不同形式油-水乳状液阐释其相应的分离机制,为后续油-水乳状液分离材料的科学设计和可控制备提供了理论依据。     

Mechanical and electret properties of polypropylene unwoven fabrics reinforced with POSS for electret filter materials

A novel polypropylene/Polyhedral oligomeric silsesquioxanes (PP/POSS) composite unwoven fabric with permanent electret was prepared through melt-blown process with corona charging. Field-emission scanning electron microscope (FESEM) and wide-angle X-ray diffraction (WAXRD) were employed to investigate the morphology of the composite fibers and the distribution of POSS nanoparticles on the surface of the fibers, respectively. POSS acted as nucleating agent and accelerated the crystallization process during nonisothermal cooling. The utmost stable charge density of PP/POSS melt-blown unwoven fabric was improved by 78.4% compared with the neat PP unwoven fabric. The maximum value of collection efficiency measured by monodisperse polystyrene aerosol (PSL) (particle size: 0.3 μm) collection could reach 97.36% for PP/POSS composite melt-blown unwoven fabric, which improved by 9% compared with neat PP melt-blown unwoven fabric. Moreover, both stress and elongation at break of the PP/POSS melt-blown unwoven fabrics were improved compared with PP unwoven fabric.     

细特丙纶针织物服用舒适性的研究

研究了细特丙纶变形丝和棉等三类针织物(起绒、毛■、纬平)的服用舒适性能,即透湿性、导湿性和保暖性,讨论了织物组织结构对服用舒适性的影响,并对细特丙纶针织物的毛细升高现象进行了分析.研究表明,细特丙纶各类针织物的透湿性、导湿性和保暖性均优于棉针织物,而棉盖丙针织物的导湿性优于丙纶和纯棉织物.     

由副产物硫酸生产白炭黑的工艺研究

在电解法制备烧碱的工业生产中,其湿氯气通常采用冷凝脱水后,再用工业浓硫酸对其进行进一步的干燥脱水,使得氯气含水量符合产品要求。经吸收水份后硫酸浓度一般在75％左右,成为副产物硫酸。用该硫酸与酿酒生产产生的稻壳灰为硅源材料生产水玻璃,采用沉淀法对白炭黑制备的工艺进行试验研究。其制备的白炭黑经质量检测符合国家产品标准。     

Development of a Novel Electrostatic Precipitator System Using a Wet-Porous Electrode Array

The authors introduce a novel electrostatic precipitator using a wet-porous electrode (WPE) array, for application to various work processes (e.g., molding and extrusion), to improve the removal performance of ultrafine particles and water-soluble gaseous pollutants generated during manufacturing. The WPE array electrostatic precipitator (WPE-ESP) consists of an ionization component for particle charging and a collection component equipped with the WPE array to maintain a high humidity environment. The performance of the WPE-ESP was evaluated in terms of the removal efficiency of airborne particles and water-soluble gases under ESP operating conditions in which the ionization charge current, the applied electric field strength of the collection component, and the relative humidity (RH) were varied. The collection efficiency of the WPE-ESP was enhanced by increasing the RH, due to water adsorption on the particle surface and the enhanced electric field strength near the collecting plate. The maximum total collection efficiency of the ESP system was ?99.2% for a 73% RH collection environment, which was approximately 3.3% higher than that of conventional dry-type ESP (C-ESP). The proposed system also removed sulfur dioxide (SO₂), a representative source (90.7%) of undesirable emissions during manufacturing processes, and mitigated ozone (O_3, <10 ppb), a by-product of the corona discharge in the ESP, regardless of the field strength. The proposed WPE-ESP included a simple mounting system; additionally, the system generated a more uniform water film than that of wet-ESPs. Thus, the WPE-ESP shows great potential for application to workplaces and machining devices that require the simultaneous removal of ultrafine particles and water-soluble gaseous pollutants.

Copyright 2015 American Association for Aerosol Research     

Evidence of powdered activated carbon preferential collection and enrichment on electrostatic precipitator discharge electrodes during sorbent injection for mercury emissions control

Removal of mercury from coal-derived flue gas by injecting powdered sorbents often involves a substantial portion removed within an electrostatic precipitator (ESP). The present investigation uses a lab-scale ESP to assess the potential for injected sorbents to collect preferentially on discharge electrode wires. Such preferential collection would increase the adsorption capacity of the accumulated dust cake on the discharge electrodes, increasing their potential contribution to the total mercury removal performance of the ESP. The lab-scale results involving various fly ashes and both carbon-based and non-carbon mercury sorbents confirm that powdered activated carbon is enriched in the discharge electrode dust cake relative to its concentration in suspension in the gas flow. Other results explore the effects of applied ESP polarity, voltage, and power, percent PAC added to the fly ash, and total particulate matter loading entering the ESP on the collection behavior.     

Horseradish peroxidase-mediated functional hydrophobization of jute fabrics to enhance mechanical properties of jute/thermoplastic composites

In this study, nonpolar octyl gallate (OG), dodecyl gallate (DG), and octadecyl gallate (OCG) were grafted onto the surface of hydrophilic jute fabrics, which were mediated by horseradish peroxidase to improve the hydrophobicity of jute materials. The gallate-grafted jutes were characterized by infrared spectroscopy and grafting percentage (Gp), and the hydrophobic properties were evaluated by water contact angle and wetting time measurements. The Gps determined by saponification was 3.91%, 5.12%, and 4.58% for OG, DG, and OCG, respectively. The nonpolar chain length and the grafting rate of the monomers had a considerable effect on the hydrophobicity of the modified jute fabrics. The as-prepared hydrophobized jute fabrics had superior interfacial compatibility with nonpolar resins, such as polypropylene (PP) and polylactic acid (PLA) making them most suitable to be utilized in the development of jute fiber-reinforced thermoplastic composites. The tensile and dynamic mechanical properties of the grafted jute/PP or jute/PLA composites were improved compared with pure PP, PLA, and non-modified jute composites.     

新型织物除锈剂氟化氢铵的研制及除锈效果

以荧石氟化钙（ＣａＦ２）或者磷肥厂尾气用水吸收的含氟化氢（４．０４ｍｏｌ／Ｌ）的废水为原料,在常温常压下合成氟化氢铵ＮＨ４ＨＦ２。经测定０８０３ｍｏｌ的ＮＨ３与０８４６ｍｏｌＣａＦ２制得的Ｈ２Ｆ２（０８ｍｏｌ）可以完全反应,制得含０６６５ｍｏｌＮＨ４ＨＦ２的溶液,收率为８３２％。该溶液对织物有明显的除锈退色作用,性能优于普通除锈剂草酸或氟化钠溶液。当ＮＨ４ＨＦ２的浓度为０９１８ｍｏｌ／Ｌ时,对白色织物上的深棕色锈斑退色效率可达８５％以上,比同浓度的氟化钠和草酸溶液分别提高１５％和２０％相对标准     

Collection and Generation of Sulfuric Acid Aerosols in a Wet Electrostatic Precipitator

Wet electrostatic precipitators (WESPs) are considered to be a possible technology for the control of sulfuric acid mist. The performance of a lab-scale WESP was investigated as a precipitator for sulfuric acid aerosol droplets produced under controlled conditions in a pilot plant. It was found that for higher levels of residual SO₂ in the flue gas, WESP collection efficiencies were greatly reduced due to aerosol formation inside the WESP. Investigations showed a strong correlation of aerosol emission from the WESP with incoming SO₂ concentration and operating voltage. It is suspected that the reactive species produced in the nonthermal plasma of the corona discharge oxidize the SO₂ to SO₃ which forms sulfuric acid. This causes supersaturation with subsequent homogeneous nucleation and thus aerosol formation.

Copyright 2015 American Association for Aerosol Research     

Microstructure and sulfonation of dual monomer-grafted polypropylene nonwoven fabrics

The sulfonation of styrenic polymers often needs harsh reaction conditions, such as concentrated sulfuric acid and elevated temperature. The awkward situation is handled by grafting copolymerization of polar and nonpolar monomers, and essentially the surface wettability between sulfonating agent and matrix polymer is circumvented in the study. Two pairs of dual monomers, glycidyl methacrylate (GMA)-acrylic acid (AA), styrene (St)-acrylic acid (AA), were grafted onto polypropylene nonwoven fabrics (PP) using thermal polymerization, and the resulted fabrics were further sulfonated using sodium sulfite and sulfuric acid, respectively. The microstructure of the modified fabrics was characterized by infrared spectroscopy and scanning electron microscopy. The ion exchange property was verified by copper (II) removal from aqueous solution, and its reutilization was carried out in electrochemical desorption process. The results show that hydrophilic and active monomer AA speeds grafting and sulfonation, but overload of AA will deteriorate copolymerization of GMA, and switch copolymerization chain component due to acylation with benzene ring. Although interfacial compatilizer promotes dual grafting, its overdosing may intensify microphase segregation of the grafting polymers owing to emulsification. The resultant granular polymers will be drained off during functionalization and reutilization processes. The ion exchange fabrics can be applied for treatment of metal ion wastewaters with unique electrochemical desorption feature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48300.     

Immobilization of glucose oxidase on nonwoven fabrics with bombyx mori silk fibroin gel

The enzyme glucose oxidase (GOD) was immobilized on the nonwoven fabrics, which have excellent properties in diffusivity of substrates, mechanical strength, and handling, with Bombyx mori silk fibroin gel. The nonwoven fabrics of silk fibroin, viscose rayon, poly-ethyleneterephthalate, 6-nylon, and polypropylene with activated surface by fluoline treatment were used. The stabilities of GOD to heat or pH changes were much improved by the immobilization as well as the case of the GOD immobilized in the silk fibroin membrane. Among nonwoven fabrics, silk fibroin was the most excellent support material for the immobilization of GOD although all nonwoven fabrics used here are able to be used as the support materials. The increase of the sensitivity was observed when the glucose sensor was made with the GOD immobilized on nonwoven silk fabrics as four times compared with the case of the GOD immobilized in the silk fibroin membrane.