Neuere Erkenntnisse und Anwendungen bei der elektrischen Abscheidung von Stäuben und Nebeltröpfchen

New insights and applications in the electrostatic precipitation of dusts and mists. The introduction deals with the basic design, the mode of operation, and the fields of application of dry and wet type electrostatic precipitators. A few important parameters which influence the migration velocity are discussed. Contrary to what the classical theory states, greater passage widths lead to higher migration velocities of the particles and thus to a higher specific efficiency. The methods for conditioning flue gases of power stations are considered, as are the experimental results obtained in an industrial-scale SO₃ conditioning plant. A new field of application is seen in the steel industry through the use of a dry type electrostatic precipitator of special design. New plastic precipitator developments for the chemical industry are discussed, and the articles closes with an account of the efforts invested in developing hot gas precipitators for higher temperatures and pressures in connection with the introduction of new power station concepts.     

Formation of alkali and alkaline earth sulfates and magnesium fluoride when magnesite is roasted in rotary furnaces,and their deposition in the electrostatic precipitators

Conclusions It is found that the caustic dust released to the atmosphere or trapped from the flue gases of a rotary furnace for magnesite roasting contains sulfur trioxide, alkalies, and fluorine, which form simple and complex sulfates of the alkali and alkaline earth metals and magnesium fluoride. The highly disperse caustic dust which is returned to the roasting furnace, and which is formed by dissociation of magnesium carbonate, is an active adsorbent, which simultaneously absorbs sulfur trioxide, alkali vapor, and fluorine, and which effectively removes these components from the outgoing flue gases.In the caustic dust found in the cyclones and electrostatic precipitators or emitted to the atmosphere, the authors have found magnesium and calcium sulfates, (K, Na)₂SO₄, vanthoffite, langbeinite, and magnesium fluoride, forming solid solutions and low-melting eutectics, and promoting the formation of strong dust deposits on the walls of the gas conduit and the exterior surfaces of the waste-heat boiler tubes. The most highly disperse caustic dust released to the atmosphere or trapped by the electrostatic precipitators contains more alkali and alkaline earth sulfates and magnesium fluoride, which form low-melting compounds, than the dust trapped in the cyclones.It is necessary to develop a technology for obtaining magnesite powder based on caustic dust from the electrostatic precipitators. This would permit the elimination of deposits from the walls of the gas conduit and the external surfaces of the waste-heat boiler tubes.Translated from Ogneupory, No. 4, pp. 22–27, April, 1979.     

A dust trapping system for rotary magnesite kilns

Conclusions By reducing the gas velocity to 0.5–0.7 m/sec and thus increasing the time spent by the gas in the electrostatic precipitator to 14–20 sec, despite the formation of intense reverse corona we can obtain 99% purification of gas in the electrostatic precipitator, given optimum agitation of the precipitation electrodes and optimum electric supply, and provided that the kiln is firing a mixture containing not more than 50% caustic dust.Changing the kiln to firing of only dust trapped in the gas purification apparatus reduces the degree of purification in the electrostatic precipitator to 97–98%.By using rational electrode agitation we can reduce the dust entrainment by a factor of 3.4 in comparison with the existing operational conditions.If the electrostatic precipitator is supplied from an AUF-400 unit, the optimum type of voltage regulation is extremal. Units of the ATF type should be used at about 100 sparks per minute.With these regimes of operation of the kiln and the rational regime of operation of the electrostatic precipitators, the total degree of purification of the gas in the dust trapping system is 99.5–99.9%.Translated from Ogneupory, No. 7, pp. 23–28, July, 1980.     

Performance evaluation of a hybrid dust collector for removing particles during subway train operation

A hybrid dust collector attached to a subway train bottom was developed for the effective removal of subway particulate matter (PM), by considering the fluctuating speed of a subway train between stations. It combines an electrostatic precipitator, which has good collection efficiency when the flow velocity is low, and an inertial dust separator, which has good collection efficiency when the flow velocity is high. The electrostatic precipitator and inertial dust separator guarantee a high collection efficiency regardless of the subway train operating speed by compensating for the other’s shortcomings. Wind tunnel test and numerical simulation were conducted to verify the performance of the hybrid dust collector. The experiment and simulation results were compared to verify the prediction accuracy of the simulation method. The collection efficiencies of the electrostatic precipitator and inertial dust separator were then simulated for various operating speeds of the subway train to predict the overall collection efficiency of the hybrid dust collector. As a result, when airflow velocity at the hybrid dust collector inlet varied from 2 to 8?m/s, subway PM₁₀ or PM_2.5 collection rate of a single hybrid dust collector was predicted to be in the range 88?～?123?μg/s or 30?～?35?μg/s, respectively. The use of multiple such hybrid dust collectors attached to the subway train bottom is expected to be effective in reducing fine dust concentration in subway tunnels.

Copyright © 2019 American Association for Aerosol Research     

浅谈静电除尘在炭素焙烧烟气净化中的应用

在电解铝用炭素阳极焙烧过程中产生含有大量沥青焦油、氟化物和粉尘等的有毒有害烟气,烟气的净化极为重要。本文就国内现主要采用的干法吸附和电捕处理焙烧烟气方法进行对比,重点对中国铝业公司青海分公司现有的电捕净化方式在实际运行中存在的问题进行探讨,从而找出改进的方法和措施。     

电收尘器的计算与选型

随着对环境保护的要求日益严格,应用一次性投资大、收尘效果好的电收尘器的单位迅速增加。收尘器的选型很关键。根据力河化肥厂磷石膏制酸联产水泥系统窑尾电收尘器的参数,详细计算电收尘器的基本型式、外型尺寸、主要参数。该厂窑尾电收尘器,入口含尘平均57g/m3,气量75065m3/h,收尘效率99.5%,与收尘效率75%的旋风除尘对比,因减少物料损失,年可增加收益95万余元。     

新排放标准下电除尘器的改造

随着环保要求越来越严格,特别是在烟尘的排放浓度上,早期投入使用的老电厂所采用的静电除尘器由于场地限制不能增加电场,已经不能满足新的排放标准要求,故对静电除尘器的改造势在必行。介绍了静电除尘器的3种改造方案：增加电场、电除尘器改造为电袋复合除尘器和电除尘器改造为袋式除尘器。通过这3种改造方案的比较及河北西柏坡发电有限责任公司4#炉由静电除尘器改为布袋除尘器的改造实例能够说明,袋式除尘器是一种高效、稳定的除尘器,它不受烟尘比电阻的影响。而且去除细颗粒能力比电除尘器好,现已成为一项成熟技术逐渐得到推广。     

电除尘设备对稀酸净化工序长周期稳定运行的保证

详细介绍了硫酸生产用电除尘器的设计、制造安装以及操作的要点。电除尘器的出口含尘量、气体温度,设备结构等设计条件要合理,电除尘器的零件、部件、整机都必须符合质量要求,制造安装质量过硬,精心操作和维护。只有电除尘器连续可靠运行才能保证稀酸净化工序长周期稳定运行。     

电收尘器在钼精矿焙烧烟气收尘净化中的应用

通过电除尘器在钼精矿焙烧烟气收尘净化中的应用,结合烟尘的物理化学性质、工艺环境和电除尘器的设备构造以及生产应用中出现的问题分析,对该工艺设备进行研究,实现了电除尘器的烟气收尘效率达99%,减少设备故障停车时间,稳定生产工艺,为后序的WSA制酸提供干净工艺气。     

The impact of fly ash resistivity and carbon content on electrostatic precipitator performance

Despite the wide use of electrostatic precipitators for particulate control in pulverised coal combustion, there are still some aspects surrounding the performance of these devices which are not fully understood, particularly with respect to high carbon ash. The introduction of low NO_x burners to meet more stringent emissions regulations has also resulted in an increase in the carbon present in fly ash. An investigation was carried to assess how the operating conditions of a pilot-scale single-stage electrostatic precipitator test facility (ESPTF) affected the collection efficiency of two high carbon fly ashes. Whilst our findings demonstrated the effectiveness of the ESPTF in collecting both fly ash and carbon particles, the performance of the high-resistivity fly ash was significantly better than expected, particularly at higher temperatures. It was concluded that ESP performance of any particular fly ash and the separation of the carbon fraction may not necessarily be predicted by its resistivity alone.     

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     

多级电场粉煤灰的质量评价及综合利用对策

本文以华能南京电厂为例，研究了燃煤电厂不同电场收捕的粉煤灰化学成分和物理性质的差异。从第一电场至第五电场，粉煤灰的平均粒径变小，常量化学成分也有一定的差别，而矿物相组成则基本相同；各种微量元素趋向在四、五电场的细粒径灰中富集。采用多个装置分别收集干灰，可促使粉煤灰资源的优化。还要尽可能降低细粒径灰逸入大气中的数量     

Rational use of caustic magnesite dust in the production of refractories

Conclusions Additionally conducted investigations showed the necessity of elimination of delivery to firing of fine dust from electrostatic precipitators contaminated with low-melting compounds of sulfur and fluorine and circulating in the kiln electrostatic precipitators closed cycle, which makes it possible to reduce the unproductive load on the dust removal equipment and discharge of dust into the atmosphere and to eliminate the crust on waste-heat boiler tube surfaces and corrosion of metal and reinforced concrete structures.The planned reconstruction of the electrostatic precipitators will make it possible to significantly increase the effectiveness of cleaning of the gases of this dust.A waste-free environmental protection method of processing of this dust into sintered clinker including removal from it and utilization of the sulfur compounds has been introduced and tested under semiproduction conditions.On the basis of the low-waste and waste-free methods developed a plan of rational composite processing of dust from cyclones into porous, dense, and fused clinkers taking into consideration solutions on preservation of the environment has been proposed. The areas of use of these clinkers for production of effective unformed and formed refractories for various purposes were determined.Translated from Ogneupory, No. 6, pp. 33–41, June, 1989.     

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     

国产化大型电除尘器的设计及在硫酸生产中的应用

总结了引进的大型电除尘器在硫铁矿制酸和冶炼烟气制酸装置中运行时存在问题的基础上,对单电场的有效长度、振打清灰效果等问题进行了改进,使我国自行设计、制造的硫酸生产用的大型电除尘器满足了长期稳定运行的要求,各项性能指标达到了设计要求,认为今后可以用国产化大型电除尘器代替引进设备。     

Vergleich von Verfahrenskonzepten zur Rauchgasreinigung bei der Rückstandsverbrennung

Comparison of process concepts for flue-gas clean-up in residue incineration. Depending on the residues being dealt with, industrial residue incinerators may produce flue gases having widely varying separation properties. This applies especially to particulate constituents. To determine unknown separation properties, to select suitable separation methods, and to predict the separating behaviour of the envisaged equipment, use can be made of pilot plants or very small test plants. Experiments have been carried out on two residue incinerators of different size using rotary-kiln technology in order to ascertain the suitability of various processes for separating particles from flue gases. For wet treatment a venturi scrubber and a scrubbing column were investigated, and for dry treatment the methods of electrostatic precipitation and cloth filtration. Various alternatives for dust separation have been derived from, and assessed on the basis of, the experimental results. Discussion of the experimental results shows that reliable prediction of the operating behaviour of industrial-scale units will require further basic investigations regarding dust separation and gas scrubbing. The task of enabling cleaned-gas values to be reliably predicted is beyond the development potential of individual manufacturers, individual operators, and individual university institutes. What is essential is the development of a joint concept under which the various tasks will be distributed and coordinated.     

Genesis of char and ash plerospheres

Plerospheres (char and ash cenospheres which have their cavities filled by finer particles of ash and other materials) occur in fly ash collected in electrostatic precipitators or other dust collecting equipment. On the basis of microscopic examination, it appears that at least some of the so-called plerospheres are formed after the major combustion stage during pulverized fuel-fired combustion. The most likely mechanism of formation is for fine ash particles to be entrained inside char and ash cenospheres either while they are suspended in the flue gas or during and after their collection in the dust collecting equipment. This hypothesis is much simpler than that proposed previously¹.     

生料收集器的研究开发

生料收集器是利用电收尘的原理将生料从烟气中分离出来，但由于烟气含灰量高，所以需从理论和实践中解决电晕闭塞问题，由于工艺流程的需要，收集器的结构设计尚须解决高负压、高温等问题。     

环境控制自动化--控制理论新的应用领域

从三废处理的典型过程出发，叙述废水生化处理过程、垃圾焚烧处理过程、废气电除尘过程的建模与控制。     

Evaluation of various particle charging models for simulating particle dynamics in electrostatic precipitators

Many numerical models have been developed to model the particle dynamics in the electrostatic precipitators in recent years. These models employ various particle charging models including field charging theory, diffusion charging theory and combined field-diffusion theory. These various charging models have different accuracy and require different amount of computational time. This work constructed a numerical model of the electrostatic precipitator and nine particle charging models were evaluated based on the existing experimental results. The results show that predictions of the constant charging models are higher than that of the non-constant models but differ little for the sub-micrometer particles. In the field-diffusion combining models, the one developed by Lawless (1996) should be the first choice relatively for numerical models of the particle dynamics in electrostatic precipitators.