ICESP X – Cairns, Queensland, Australia, 2006

• 22/05/2023

The International Conference on Electrostatic Precipitation (ICESP) is the official conference of the International Society for Electrostatic Precipitation (ISESP). The following is a list of papers from the X ICESP Conference under their respective topic. Click on the papers title to view the complete paper in PDF format.

Session 1A – Opening Session (Monday, June 26, 2006)

• 1A1 Atmospheric Pressure Nonthermal Plasma Decomposition of Gaseous Air Contaminants and that Diagnosis
  • Environmental application of atmospheric pressure Non-Thermal Plasma was developed by late Prof. Masuda as PPCP (Pulse-discharge induced plasma chemical process) or SPCP (surface discharge induced plasma chemical process). Application field-tests for DeNOx and odor improving were reviewed where some are applied for exhausting gas process in various factories. New technology for decomposing VOCs is also explained including dioxin decomposition. Other new application area of the non-thermal plasma are also introduced. The optical diagnosis of the nonthermal plasma is also described.

Session 2A – ESP Applications I (Monday, June 26, 2006)

• 2A1 The Influence of Flow Distribution on the Performance Improvement of Electrostatic Precipitator
  • Particulate matter emission is one of the major air pollution problems of coal fired power plants. Though fine particles constitute a smaller fraction by weight of the total suspended particle matter in typical particle emissions, they are considered potentially hazardous to health because of their high probability of deposition in deeper parts of the respiratory tract. Electrostatic precipitators (ESP) are the most common, effective and reliable particulate control devices which can handle large gas volumes with a wide range of inlet temperatures, pressures, dust volumes and acid gas conditions. Though the electrostatic precipitators are generally running at the collection efficiency as high as 99.95%, the anticipated regulations on particulate matters of 2.5 microns (PM2.5) have led the local power station to explore improvement options to further control the emissions of the fine particulate at a minimum cost even its current particulates emissions are well under the limits of its current environmental license. The performance of Electrostatic Precipitator (ESP) is significantly affected by its complex flow distribution. In this study the gas flow through the ESP at a local power station is modelled numerically using computational fluid dynamics (CFD) code Fluent to give insight to the flow behavior inside the ESP. The flow simulation was performed using the Realizable k-e model. The results of the simulation are discussed and compared with on-site measured data supplied by the power plant.
• 2A2 Model Experimental Research of Skewed Gas-Flow Technology
  • Aiming to the research project of renovation of electrostatic precipitators for large-scale Sinter of iron and steel plants, this paper has carried out model experiments through installing guide plates and baffler to adjust the airflow inside precipitator to the predestined skewed profile pattern and analyzed the impact of adjusting device on airflow distribution and finally ascertained the executive plan of skewed gas-flow technology (SGFT).
• 2A3 Secondary Flows and Turbulence for Staggered and Non-Staggered Electrode Emitters
  • Simulation models for sizing ElectroStatic Precipitators (ESPs) have been presented for the last 15 to 20 years. But still today the majority of the models are two-dimensional or semi-two-dimensional. Such restrictions exclude the possibility for investigating the influence of the physically important secondary flows (‘ion winds’) induced by the electric field. Secondary flows aid or oppose particle motion towards the collecting plates which along with turbulent diffusion play an important role in the resulting computed particle emission from a given ESP. But secondary flows are also found to determine the level of turbulence, which affects directly the coefficient of turbulent diffusion since this is often assumed to be proportional to the eddy diffusivity of momentum exemplified by the k,e- model.Experimental results obtained in a 0.2×0.2 m by 1.0 m long, seven-electrode laboratory scale model ESP at low particle load are used to first verify the reliability of the present CFD-model for staggered and non-staggered electrode emitters, in terms of current-voltage-characteristics, current density at collecting plate, turbulence level, and strength of secondary flows. Then parameter studies illustrate how the level of turbulence and the pattern and strength of secondary flow change, both along the ESP for fixed current and at the downstream station for increasing current. The distribution and magnitude of the turbulent diffusivity as well as computed efficiency are discussed.

Session 2B – ESP Fundamentals (Monday, June 26, 2006)

• 2B1 Experimental Test of Discharge Electrode for Collecting of Fly Ash of Different Physico-Chemical Properties
  • This paper describes experimental test results of selected discharge electrode configuration on ESP fly-ash collection derived from boilers fired with coal and biomass mixtures. According to the new Polish Energy Law energy sector should increase its renewable energy quota up to 5,75% by the end of 2010 year. A new specific type of the after-combustion product should be efficiently collected within the ESP. To estimate the new precipitation’s process parameters, series of test were carried out on a bench scale ESP model collecting fly ashes coming from utility boilers fired with lignite and lignite-biomass mixtures. The physical model had active field length of 2 x 1000 mm and 450 mm height with a gas duct spacing of 400 mm. The main goal of the experimental investigation was to assume the dependency of ESP collection efficiency on discharge electrode type, especially when collecting fly-ash generated in utility boilers fired with coal-biomass mixtures. The investigation takes into account the chemical and physical characteristic parameters of the fly ash as well as the mercury content in fly ash as a function of particle size distribution.The results has been presented in the form of tables and curves showing the influence of electrical energization, fly ash chemical and physical specific properties and discharge electrode configuration on the total collection efficiency of an ESP.
• 2B2 Influence of Re-entrainment and Charged Particles on Particle Deposition on Downstream Wall in an Electrostatic Precipitator
  • One application of an electrostatic precipitator (ESP) is decontaminating polluted gases in expressway tunnels to save drivers and environment around tunnels. High collection efficiency is well achieved by a conventional ESP. However, the walls downstream the ESP are polluted due to particle deposition. Although it was thought that the cause was the emission of charged particles from the ESP, authors thought that one of the causes was also particle re-entrainment on the ESP. In this paper, the experiments were carried out to investigate the effect of neutralization on preventing particle deposition. The collection efficiency as a function of particle diameter and the amount of deposited particles on the wall were studied on three types of the ESP, which were the universal ESP under DC operating mode (DCESP), the ESP under AC operating mode (ACESP) and the ACESP with neutralization. The ACESP is new type that is developed to prevent the particle re-entrainment by authors. The results showed that the collection efficiency of a large particle decreased on the DCESP because of the particle re-entrainment. Although the amount of deposited particles on the DCESP was the greatest, that on the ACESP was low due to preventing particle re-entrainment. The ACESP with neutralizer was most effective to decrease the amount of deposited particles of three types of the ESP, because of the preventing particle re-entrainment and the decreasing the charge amount of gases downstream the ACESP with the neutralization.
• 2B3 Experimental Study on Agglomeration of Smole Particle in Electric Field
  • The agglomeration phenomenon of the charged smoke particle has been investigated by the electric- fluid mechanics and transport theory of external force field and depending on several simplifying assumptions the theoretical expression for the agglomeration rate of the smoke particles has been developed. In a model of electrostatic precipitator the agglomeration mechanism of charged particles has been studied further. It is shown that the agglomeration of the charged smoke particles are affected by charge distribution on the surface of particles, particle size and charge polar of particle, particle charges and so on. No matter single polar corona or bipolar corona the agglomeration of smoke particles will take place but the agglomeration occurring between particles with negative charges and particle with positive charges will be limited within a certain scope.

Session 2C – Cold Plasma and Multi Pollution Control I (Monday, June 26, 2006)

• 2C1 Pilot-Scale NOX and SOX Removal from Boiler Emission using Radical Injection and Chemical Hybrid Process
  • The pilot-scale NOx and SOx simultaneous removal from boiler emission was performed using radical injection and chemical hybrid process. The radical injection is often called as indirect plasma (or remote plasma) and air radicals are produced at room temperature with less than 1/10 of the flue gas flow rate. The flue gas from the boiler was in the range of 450~1,470 Nm3/hr, the gas temperature of 280oC, and NOx concentration of 30 ppm for city gas, and 70 ppm of NOx and 35 ppm of SOx for heavy oil, respectively. The radical injection was demonstrated to be extremely effective for NO oxidation especially when the flue gas temperature is in the range of 300oC where NOx is rather generated at this temperature range. The produced NO2 was further reduced to N2, and nontoxic and water soluble Na2SO4 by Na2SO3 solution in the chemical scrubber. For the case of oil firing boiler SO2 was simultaneously adsorbed by NaOH solution. The NOx removal efficiency for gas firing exceeds 90% but NOx removal efficiency for oil firing was in the range of 60% due to the lack of radicals and ozone concentration with the pulse power supply used. The removal efficiency of SO2 was in the range of 85~90%. The NOx removal efficiency was evaluated by the ratio of the radical flow rate by the indirect plasma to the primary flue gas flow rate, specific energy density, and Na2SO3 concentration and chemical flow rate. Scrubbing solution was chemically analyzed and it is confirmed that the waste solution can be disposed outside of the plant.
• 2C2 Electrocore Technology Development for Multi-Pollutant Control
  • United Technologies Corporation is developing the ElectroCore technology for multipollutant control on coal fired power plants and other applications. This development combines physics-based modeling with pilot testing and has been carried out in conjunction with Southern Company, Alabama Power and EPRI. Two independent physics-based models for the ElectroCore precharger and separator were developed at the United Technologies Research Center (UTRC) in collaboration with the Russian Academy of Sciences. The precharger model calculates the electrical charge on a particle passing through the precharger and the separator model calculates mass separation efficiency. The modeling has successfully predicted pilot separation efficiency trends and the 98–99% particulate separation efficiency achieved in the latest pilot tests. UTC plans to continue the ElectroCore technology development through continued modeling and pilot testing, a full scale, industrial demonstration project and the investigation of alternate applications in coal gasification, industrial processes and indoor air quality.
• 2C3 NOX Removal using DBD with Urea Solution and Plasma Treated TiO2 Photo Catalyst
  • Two kinds of experiments for NOx removal have been carried out. One is the experiment using dielectric barrier discharge (DBD) with the aid of adding urea solution. The other is the experiment with plasma treated TiO2 photo catalyst. For adding urea solution the energy efficiency of NOx removal by DBD is better than without the adding by more than 10 times at Vac ~7.2kV. The adding water only also shows good result. So the improvement in NOx removal by DBD with urea solution is not only due to urea but also water. TiO2 films are developed on the one side of a quartz tube at 500oC by use of the sol-gel method. Then the TiO2 films have been processed in hydrogen or nitrogen plasma. The difference of NOx removal rate between the plasma treated films and no treated films has been measured, in which measurements a chemical lamp, black light and fluorescent lamp were used. The results show that the hydrogen plasma treated film is the most efficient as photo catalyst for NOx removal.

Session 3A – ESP Applications II (Monday, June 26, 2006)

• 3A1 Electrostatic Precipitator Performance in Indian Pulverized Coal based Thermal Power Stations – Problems and Solutions
  • Coal used in Indian thermal power stations is of inferior grade having low heat value and high ash content due to drift origin. However, Indian power coal ash is specially known by its refractory in nature and low sulphur (below 0.5%) and alkalis (less than 1.5%) contents. Due to presence of low sulphur and alkalis and consequently having very high ash resistivity (1012 – 1014 O cm) it is difficult to achieve good E.S.P. performance. Majority of Indian thermal power stations have E.S.P. for ash collection.In the present paper various attempts have been made to analyze the causes of problems in terms of the chemical constituents of ash, resistivity, conductivity, etc. A special emphasis was given to correlate the different forms of sulphur (organic, pyretic and sulphate sulphur) on E.S.P. performance. The total sulphur can not predict the E.S.P. performance; it is the forms of sulphur that decides the performance. Organic sulphur in coal mainly improves the ash resistivity through SO3 adsorption from flue gas whereas pyretic sulphur is responsible for slag and clinker formation in the boiler and evacuated through bottom hoper as bottom ash in dry bottom furnace.In addition, the paper deals with the concept of predicting ash resistivity based on conductivity measurement of ash – extract which may help to take necessary action for improvements of E.S.P. performance in thermal power stations. The paper also discusses the remedial measures to be taken in terms of use of additive (sodium / sulphur based) or biomass like horticultural waste having high alkalis (4 – 6 %) for blending in appropriate proportion with coal depending on characteristics.
• 3A2 Electrostatic Precipitator Performance with Chinese Coals
  • The electrostatic precipitator (ESP) performance is sensitive to fly ash properties. The ESP size and design for a new installation has to be carefully selected based on coal and coal ash data together with operating conditions. Experiences from similar installations are utilized as base for new ESP sizes and for upgrading of existing ESP’s.Chinese coals are now often seen in specifications for new plants together with other export coals from e.g. Australia, South Africa and Indonesia. In China new ESP’s are built and existing ESP’s are upgraded to encounter an increased power demand and comply with more stringent emission requirements. Knowledge about the properties of fly ashes from Chinese coals is necessary to provide a good basis for ESP performance predictions. Mineral analyses and laboratory combustion studies were made for selected Chinese coals to provide deeper knowledge about ash properties, which are of importance for the ESP operation.Some Chinese coals are characterized by high aluminum contents in the ash compared to other commonly used coals. These coals often generate back-corona conditions in the ESP. A high content of aluminum in comparison with silica indicates high contents of minerals like kaolinite and aluminosilicate, which often have fine mineral size distributions in the coals. Sodium and iron are generally known to be beneficial for the ESP operation. In some Chinese coals more sodium and iron are associated with aluminosilicates than for non-Chinese coals. The influence of sodium and iron on ESP performance is certainly dependent on in which form sodium and iron occur in the coal.
• 3A3 Industrial Demonstrations of a Three-Phase T/R Power Source with Coal Fired Power Plants
  • This paper describes a new three-phase T/R power source together with its automatic voltage controller. Since May 2005, the power sources have been applied in two Chinese 125 MW coal fired power plants. Six months industrial demonstrations indicated that in contrast to conventional single phase T/R, the three-phase T/R can significantly increase the corona current. The voltage ripple is around 3-5% only. Meanwhile, its power factor is around 0.9. By using the new AVC, upto 60% of electricity consumption can be saved.

Session 3B – ESP Fundamentals II (Monday, June 26, 2006)

• 3B1 Complex Analysis of Ionic Wind in ESP Modeling
  • Several experimental and theoretical works pointed out that ionic wind that produces secondary flow inside the ESP channel distorts the carrier gas velocity distribution and particle trajectories and hence influences on the precipitation process.For valid description of the effect of the ionic wind a complex model is necessary that takes into consideration the interaction between the gas flow and the corona discharge. However, traditional ESP models approach this problem usually in a simplified way. One group of the models determines the gas velocity distribution in the ESP channel first and considers it as being constant during the further calculations. Another group of the models is focusing only on the corona induced secondary flow itself, ignoring the operational conditions including the effect of the turbulent gas flow and particle space charges.To handle the difficulty of the interaction between the gas flow and the ionic wind caused by the corona discharge, a new development of our ESP model has been carried out. With help of the new model complex analysis of ionic wind became possible for different operational conditions. Further development of the present state is needed for examination of parameters that are influenced by the ionic wind induced secondary flow. Coupled electric field, fluid dynamic and also particle transport simulation is under continuous development with the aim of determining the role of the ionic wind in particle transport modelling. Based on the calculated preliminary results already valuable conclusions can be drawn on the effect of the ionic wind in ESP modelling for the single wire sectional model.
• 3B2 The Newest Research Results for Collection of High Specific Resistivity Dusts with Electrostatic Precipitators
  • In this paper the newest results in industrial ESPs for collecting high resistivity dusts are summed up as follows:(1) The negative resistance zone in the V-A characteristics when back corona occurs is not a inevitable result due to back corona, but due to the characteristics of the energization to the ESP. With modern techniques is able to stop the appearance of the negative resistance zone by accurate recognition of back corona signals, tracking and controlling them.(2) Three joint hazards due to electrostatic attractions, electrostatic repulsions and back corona discharges may exist when ESPs are used to collect high resistivity dusts, leading to a far lower precipitation efficiency than that for common dusts.(3) For collection of high resistivity dusts with ESPs. If accurate recognition of back coronas, tracking and controlling them to increase effective voltage and corona current as a means to increase dust partic le charging can be realized then the structure design of the ESPs and the mode of the energisation would not obey the formula jpd=Es. On the contrary if ESPs with narrow gaps, strong corona cathode wires and the electric field strength same as that in wide gaps ESPs are adopted collection of high resistivity dust can be remarkably increased.
• 3B3 Back-Corona Model for Prediction
  • The back-corona discharge is formed by a series of micro-discharges in the air spaces between the partcles of the dust layer deposited on the collecting plates. It starts when the particle resistivity is quite high: it changes the voltage-current characteristics of the electrostatic precipitator and significantly lowers its efficiency.In the present work, the variation of the voltage-current characteristics, depending on resistivity and particle layer thickness, has been successfully reproduced by a simple electrical circuit model of the dust layer, including a back-corona current generator and the voltage drop across the particle layer.The model also includes an estimation of the variation of the captation efficiency: as backcorona lowers the ion space charge, the computation of the back-corona current allows to evaluate the variation of the particle charging rate and therefore of their migration velocity.

Session 3C – ESP Fundamentals II (Monday, June 26, 2006)

• 3C1 Reduction of Ozone Generation in Electrostatic Precipitator
  • The influence of electrode shape on ozone generation in electrostatic precipitator (ESP) has been experimentally investigated. It experimented by using the two-stage-type ESP composed of a precharger and collecting section. In the precharger section, three types of high voltage electrode of a wire, a thin plate, and a saw-tooth were used to experiment. Each ground electrode used a plate. The collecting section had a parallel-plates configuration. The gases exhausted from the diesel engine were diluted with air and introduced into ESP. The electrical characteristics in a corona discharge on each electrode are summarized. The corona discharge luminescence was observed by each electrode type. In the positive corona discharge, the thin plate type electrode has shown low ozone generation compared with the wire type. In the negative corona discharge, the saw-tooth type electrode has also shown low ozone generation compared with the wire type. All current characteristics of the collection efficiency of the wire and the thin plate were almost the same. Those of the wire and the saw-tooth in negative polarity were also almost the same. These results have great practical importance for improving the performance of the two-stage type electrostatic precipitator as it allows the collecting efficiency of the unit to be increased without exceeding the ozone generation.
• 3C2 The Effect of the Third Electrode on the Ozone Generation of a Wire-Plate Type Non thermal Plasma Reactor with a Slit Barrier
  • The effect of the third electrode on the ozone generation of a wire-plate type nonthermal plasma reactor, with a slit barrier, has been investigated experimentally. When a third electrode is installed on the slit of the slit dielectric barrier, where the surface corona discharges occurred, it is found that a significantly increased ozone generation could be obtained for negative corona discharge. This, however, indicates that the third electrode can control the discharges, not only the corona-wire discharge but also the slit discharge on the barrier in the plasma reactor. As a result, a naked wire, which is used as a third electrode, significantly influences the fields of the corona wire and the surface charges. An insulator-wrapped wire also has a strong effect on the discharges. As a result, a high amount of the output ozone can be obtained with the third electrode of a naked wire of the open terminal case and an insulator-wrapped wire of a 20-Mohm-resistance, respectively
• 3C3 Relationship between Ozone Formation and Toluene Decomposition Efficiency in a Zeolite-Hybrid Plasma Reactor
  • A zeolite-hybrid plasma reactor showed the excellent performance for the toluene decomposition by the cyclic operations such as long time toluene adsorption followed by short time plasma discharge. In particular, the decomposition efficiency of toluene was enhanced by placing the zeolite in the downward position of the plasma region rather than placing that in the upward position. On the other hand, it was found that the fast electron could not reach in the internal area of the zeolite, which was effective for VOCs plasma decomposition in gas phase. Then, we investigated the reaction mechanism rela ted to active oxygen species by tracing the behavior of ozone formed in the reactor. Actually, the formation of ozone was suppressed in the zeolite- filled region, although the concentration of ozone formed in the plasma region gradually increased in the gas flow direction. That is, the toluene adsorbed on the zeolite was scarcely decomposed in the upward position, while it was readily decomposed in the downward position. These results can be well explained the positioning effect of zeolites, and lead to the conclusion that the synergistic effect of plasma and zeolite was substantially ascribed to the following mechanism; active oxygen species formed by the plasma diffused easily into the micropore, and then promoted the decomposition of C6H5CH3 adsorbed in the internal area.

Session 4A – ESP Applications III (Monday, June 26, 2006)

• 4A1 Sizing and Design Experiences of the Electrostatic Precipitators for Two 600 Mw Power Generating Units
  • Hequ Power Plant has two 600MW units burning Hequ coal with its mine very near Zhungeer coal mine. Both coals are low sulfur of 0.44%~0.48%. It is well known that Zhungeer coal is the most difficult coal for ESP applications in China. As a result, ESPs burning Zhungeer coal with large SCA’s of 140m2.s/m3 and huge actual specific power consumptions of 1740w/1000m3/h (corresponding a calculating current density of 0.838mA/m2 collecting area) have still operated with dust emissions of 110mg/m3. The selection of a suitable SCA and current density for the Hequ coal ESP was made only after a very careful analysis of the difference between coals. As a result, a much smaller design SCA value of 97.64m2.s/m3 and 0.2~0.3mA/m2 current density were selected; actual operation has proved the design was successful. The number of T/R sets also reduced to one half that used on the Zhungeer coal ESPs.In addition, the use of a new design method for combining the US top rapped support system with Europe type collecting plates, and the use of special rapping acceleration tests and optimized structural designs resulted in the Hequ ESP achieving a very light specific weight of 26.8kg-steel/per square meter collecting area (2521 ton for one 600MW unit). Comparing this to the average value of Chinese ESPs, about 23% percent less steel was used and more than 1/4 of the cost was saved.In October of 2004 and February of 2005, these two 600MW ESPs have been put into operation respectively. Satisfactory operation and anticipated emissions were achieved.
• 4A2 Removal of Marine Diesel Particulate Matter by Electrostatic Precipitator
  • Diesel particulate matter exhausted from marine diesel engine during the combustion process cause a various human health and environment impacts. Many methods were applied to control mass concentration of particulate matter from diesel exhaust gas. This research has been developed applying an electrostatic precipitator (ESP) to reduce marine diesel particulate matter. The objective is to investigate experimentally ESP’s performance on reducing diesel particulate with variation of exhaust gas temperature. Using a single stage and wire-plate type of ESP, the diesel particulate characteristics, such as mass concentration, composition (SOF and DS), size distribution and mean diameter of the aggregate particulates, under different engine operating conditions, are analyzed. Effects of exhaust gas flow on ESP’s performance and operating duration of ESP are also discussed. The results show that applied ESP can reduce particulate mass concentration. The particulate mass concentration that reduced depends on gas temperature and initial particulate mass concentration. ESP could reduce the Soluble Organic Fraction (SOF) greater than Dry Soot (DS), and the mean diameter of aggregate particulates decreases.

Session 4B – ESP Fundamentals III (Monday, June 26, 2006)

• 4B1 A Friendly Tool to Assist Plant Operators and Design Engineers to Control Fly Ash Emissions: ORCHIDEE
  • Either in the Operation Control Room, the Handling/Logistics Department, the Maintenance Department…or even in the Environmental Section, the operating personnel can contribute to control the dust emission of a power plant unit.To satisfy current regulations, the efficiency of the electrostatic precipitator must always be mantained greater than 99.5%. These high performances require continuous control of the impact of possible malfunctions on the emission level, by adjusting the process conditions from the coal yard to the stack, including the electrostatic-precipitator itself.To evaluate quickly the impact of coal characteristics, combustion parameters and electrical malfunctions on dust emission the operator can use a user-friendly software based on physical modelling of the dust collection process: ORCHIDEE. Without using experimental databases or manufacturer’s empirical data, the operator becomes able to get a better real time understanding of the problems, and to react efficiently.Version 2 of ORCHIDEE software offers additional functions, based on the non-linear coupling of different effects (ash layer chatacteristics, particles resistivity, current and voltage rapping processes, etc.)By proper introduction of all input data, ORCHIDEE 2 makes possible:
    – to evaluate the impact of combustion parameters on dust emission (excessive airleakages, flue gas temperature at precipitator inlet).
    – to test blending hypotheses of various types of coal to avoid back-corona.
    – to evaluate the impact of rapping sequences or SO3 injection on dust emission.
    – to simulate electrical malfunctions: field or section out of service, wire and plate fouling, electrode misalignment, etc.
    – to evaluate the impact of back-corona on precipitator efficiency and voltage-current characteristics.Validated with industrial precipitators data, ORCHIDEE is a very helpful tool to assist operation and maintenance of electrostatic filters. It is unique for its high scientific content and its user-friendly interface, and it has already shown to fulfil the expectations of industrial users.
• 4B2 The Study on Simulation of Optimize Control System for Electrostatic Precipitator
  • The thesis hammered at the study on simulation of Economize on Energy & Optimize control system for Electrostatic Precipitator (ESP). To get the highest efficiency, namely the lowest dust discharging concentration, the software can automatically select different controlling style and electric-field characteristics according to different working stations. Based on simulation of distributed control system of ESP and a series of established mathematic models, the software can finally find best controlling style after a series of analyses. In the light of optimize control theory, this simulation software of Economize on Energy & Optimize control system for ESP was developed. The software can run independently on distributed control system of ESP. A large number of simulation experiments manifested what is followed: the simulation software have a good man-machine interface and simple operation; the expected goal of optimize control was achieved, at the same time energy was economized. It can make great importance and reference on development of ESP-control software and improvement of ESP power supply control.

Session 4C – Cold Plasma and Multi Pollution Control III (Monday, June 26, 2006)

• 4C1 Enhanced Mercury Collection Using the Indigo Agglomerator
  • Recent regulations in the US require Mercury emission control on coal fired power stations. Mercury is considered a major health hazard because it concentrates in the food chain and, in particular, may result in very high concentrations in some fish. The Indigo Agglomerator enhances Mercury collection by increasing the interaction between the Mercury, in the form of elemental or ionic molecules contained in the gas stream, and the adsorbent, either injected Activated Carbon or using the LOI from the combustion process. Initial tests have shown a factor of four enhancement of the Mercury removal when an Indigo Agglomerator is installed in front of an electrostatic precipitator. This is in compliance with the long term EPA requirements in the US.
• 4C2 Advanced Particulate and Mercury Removal Technology
  • Historically, coal-fired boilers have utilized electrostatic precipitators for particulate removal. As environmental regulations become more stringent and enforcement becomes more consistent, electrostatic precipitators are challenged to provide continuous compliance.As a result, many coal-fired boiler operators are considering pulse jet fabric filters to provide continuous particulate compliance. However, there can be operational penalties experienced when this switch is made.Traditional pulse jet fabric filters introduce increased pressure loss to the system. This loss is in the range of 150 to 250 mm of water. In addition, compressed air used to pulse the filters can account for a major operating expense. The requirement to replace filter bags every three to four years is a major expense.Based on the need to increase particulate removal efficiency while minimizing the impact on plant operating costs, an alternative to a conventional pulse fabric filter is required.

Session 5A – ESP Applications IV (Tuesday, June 27, 2006)

• 5A1 Sonic Horns have Fully Replaced the Tumbling Hammer Rapping in an ESP for the Sieving System of Iron Ore Sinter Machine
  • In China, firstly using sonic horn fully instead of tumbling hammer to rapping down the dusts from the ESP electrodes of a sinter band sieving system in Jiuquan Iron and Steel Company was carried out in May 2004.This one chamber three fields ESP have a flowing cross section area of 60 m2 with a design collection efficiency of 90%. Its tumbling hammer rapping devices encountered a lot of troubles, so that it must be fixed through about every one month with a spare parts expense of 70~80 thousands Yuan RMB for one year. After the first overhaul in August 2002, the dust emission has been 120 mg/Nm3.Therefore, it was tried to use the sonic horn solely instead of the original tumbling hammers for rapping down the dust from both of the corona and collecting electrodes. The horns were put into operation since May 2004. Till now, the once year smooth operation shown that satisfying result given a emission of 80 mg/Nm3 have been reached. Because of the non-contact rapping does not injure any ESP inner parts, the spare parts expense and the repair fee were saved.The principle of sonic rapping and the design features are also explained shortly.
• 5A2 Sizing and Design of Electrostatic Precipitators for Iron Ore Sinter Band
  • As the development of sintering process and growing strict regulation on particulates emission, the requirement on sinter waste gas electrostatic precipitator (hereinafter referred to as ESP) becomes more and more stringent. However, processes such as high degree of alkali sintering process and operating under high negative pressure have significantly effected on process ESP. In this paper, several issues are fully discussed which should be taken into account when sizing ESPs based on the features of gas and particulates to be treated by process ESP for a sinter in order to meet the requirement of process dedusting for a sinter, to reach the aim of gas purification.

Session 5B – ESP Fundamentals IV (Tuesday, June 27, 2006)

• 5B1 Spark and its Effect on Electrostatic Precipitator
  • The role of components in an Electrostatic Precipitator (EP) for a spark and both the phenomenon and mechanism of a spark are elaborated and then the type of spark is classified by the condition of shortage between the discharge and collecting ele ctrodes. The secondary voltage and current waveforms of a spark are discussed in order to address the severe effect of the secondary and primary current spikes while a spark occurs. The fundamental difference between a spark and its detection algorithm in a wet EP and a dry one is explained so as to clarify why the spark detection for a wet EP cannot work for a dry one. The problem of frequent sparking in a dry EP is addressed together with the explanation on the disadvantage of the spark detection and control algorithm adopted in most AVC in service today. The effectiveness and significance of the damage caused by sparks on both primary and secondary sides of the electrical circuit of an EP are elaborated with two field cases as respective demonstrations. The investigations’ results and solutions developed thereby in these two field cases are given together with the observations after implementing the solutions. Further, an enhanced algorithm of spark control is proposed in order to overcome the problem of frequent sparking in a dry EP.
• 5B2 Universal Relationship between Collection Efficiency and the Corona Power of the Electrostatic Precipitator
  • The basic principles of aerosol and particle collection using the electrostatic precipitation process are well understood as the result of extensive laboratory and field testing carried out over almost a century. Thanks to these tests the phenomena of ionization by corona discharge, particle charging and collection, the influence of gas velocity distribution and gas flow turbulence, and so on, are now reasonably clear. The numerical prediction of the main design parameters of the ESP is less advanced due to the very complex flow phenomena which are the result of the interaction between a high-strength electric field, a turbulent gas flow field, and the motion of particulates. Therefore, to date the widely used ESP design approach is based on the systematic accumulation of performance data from existing devices. On the basis of these performance data one can evaluate the collection efficiency, electrical power and main design parameters of new ESP installations. Designs based on existing devices require experience, talent and engineering intuition. The importance of these qualities cannot be denied, nevertheless the design of an effective and optimal industrial ESP has to be based on basic principles and fundamental universal relationships that are still missing.In this paper we will discuss one of such theoretically derived approaches which describes the relationship between collection efficiency and the corona power of the Electrostatic Precipitator.

Session 5C – ESP Fundamentals IV (Tuesday, June 27, 2006)

• 5C1 Short Gap Non-Thermal Plasma Performance to Decompose Dilute Trichloroethylene
  • In order to improve the energy efficiency in decomposing dilute trichloroethylene (TCE) by the nonthermal plasma, a new plasma reactor is examined with different discharge gaps (0.4 mm, 2.4 mm, 3.4 mm, and 5.4 mm) and a short gap plasma reactor is the best among them. New manganese oxide-supported alumina spheres are used as the ozone decomposer to enhance the TCE decomposition efficiency by the products (maybe oxygen radicals) of the ozone decomposition. Those new MnO2-supported alumina works very well to decompose TCE. 99.5 % of 250 ppm TCE in the air is decomposed when the specific discharge energy density (SED) is only 15 J/L by the Direct Method with MnO2. That SED value is very compatible to other commercialized catalyst. Close to 100 % carbon mass balance is also realized at SED of 90 J/L where that SED value for a similar level carbon mass balance was more than 400 J/L in the former data.
• 5C2 Application of Non-Thermal Plasmas to Gas Cleaning and Enhancing Combustion for Pollution Reduction
  • For more than two decades, interest in gas-phase pollution control has greatly increased, arising from more attention to the health and economic effects of pollution, a greater respect for the environment, and a larger body of laws and regulations. Non-thermal plasma (NTP) technology shows promise for removing pollutants from gas streams and cleaning contaminated surfaces, using plasma-generated reactive species (e.g., free radicals). Such plasmas, where electrons are energetic (~ few eV) and the gas temperature is near ambient (~ 300 K), can generate both oxidative and reductive radicals – showing promise for treating a variety of pollutants, sometimes simultaneously decomposing multiple species. NTPs can also be used to ‘activate or ‘crack’ hydrocarbon fuels, which promotes the combustion of the fuels (reducing unburned hydrocarbons and allowing fuel burning in regimes where the emissions of CO and NOx are expected to be reduced; e.g., ultra-lean-burn conditions). In this paper, we will review selected experiments and field tests related to the cleaning of VOCs (volatile organic compounds) and NOx from gas streams, using NTPs and discuss a particular NTP source for surface decontamination (radionuclides and chemical/biological warfare agents). The remainder of the paper will focus on experiments devoted to non-thermal plasma-assisted combustion, using model gaseous fuels (like methane, propane, and butane) and alluding to the possibility of applying the process to liquid fuels (like iso-octane, a gasoline surrogate). We will present experimental results demonstrating that NTPs can affect flame stability and, in this way potentially reduce the emission of pollutants.

Session 6A – ESP Applications V (Tuesday, June 27, 2006)

• 6A1 Enlargement of Mist Particles for Wet Type Electrostatic Precipitator
  • Gaseous SO3 (H2SO4) condenses into a nucleus and becomes sulfuric acid mist in a cooling process such as the wet flue gas desulfurization system (WFGD). The relation between the temperature condition of this cooling process and particle size of mist was examined by condensation theory and experiment s. In addition, the collecting efficiency and electric current density of a wet electrostatic precipitator (WESP) were examined with the mist generated by the cooling process.Particle sizes of mist were measured at 30 ppm of SO3 under various cooling conditions, and were measured in the case where fine particles of ammonium sulfate were supplied by spray-drying.The particle size of the nucleus into which mist condenses depended on the speed at which the gas is cooled. At a slower cooling speed, mist did not condense into small particles. This indicates that the particle size of mist grows in the range where the gas temperature around the SO3 condensation temperature is lowered slowly. The electric current density of THE model ESP increased when the particle size of mist was larger, and the collecting efficiency was improved, too. This indicates that the specific collecting area of the ESP is influenced by the cooling condition.
• 6A2 Enhanced Fine Particle Collection Using the Indigo Agglomerator
  • Fine particles are a major health issue as they remain suspended in the atmosphere for extended periods, are able to penetrate deep into the human lung and contain significant concentrations of heavy metals, such as Arsenic. They are also a significant component of the smog that limits the visibility in many cities and even in some national parks plus scientists believe they have an effect on global weather patterns. The Indigo Agglomerator enhances fine particle collection by attaching the fine particles to the larger particles. These large agglomerated particles are easily collected in existing control devices, such as electrostatic precipitator, fabric filters, scrubbers and cyclones. This paper concentrated on PM2.5 particles, that is particles less than 2.5um in diameter, including data that was collected on particles down to 50nm in diameter. It was found that the reduction in fine particle emission from an electrostatic precipitator provided by installing an Indigo Agglomerator increases with reducing particle size from a factor of 5 at 2um to a factor of 10 at 100nm. Reductions of this magnitude will have a significant effect on the impact of fine particles on both visibility and health. It will also result in a reduction in heavy metal emissions.
• 6A3 Reduction of Fine Particulate Emmissions from ESPs
  • World wide the focus on the health impact of fine particles in the atmosphere is increasing and regulatory restrictions on size dependent emission are expected soon to add to the ever descending total mass limits of all countries.The content of hazardous particles may be reduced either by means of sophisticated devices targeting the fine fraction directly or simply aim at reducing the total mass emission to “zero”. The latter may be done by fabric filters or by means of high efficient ESPs and is expected to comply with the demands.Barrier filters are characterized by having eliminated many of the non-ideal boundary conditions that maintain the ESP on higher emission levels – either due to constant contributions (re-entrainment, sneakage) or intermittent contributions (rapping loss). Many of these effects may be eliminated or minimised in ESPs e.g. by means of an efficient baffling system, electrode optimisation, etc.This paper describes a series of case stories where dust emission is reduced to the 1-10 mg/Nm3 range and has a low content of fine particles (PM2.5) as well. This shows that in many cases dry ESPs as well as fabric filters are valid alternatives as “best available technology” (BAT) in fine particulate removal.
• 6A4 Sub-Micron Particle Removal Efficiency of Electrically Enhanced Wet Scrubber
  • Wet scrubbers are mainly used to remove undesirable gaseous components from flue gases. Normally most scrubbers have low removal efficiency for fine particles. One way to increase the fine particle removal efficiency is to use pre-charging. Particles can be charged by corona discharge like in an electrostatic precipitator.Charged fine particles are removed by the combined effect of
    i. Inertial impaction of particles and droplets
    ii. Diffusion of particles to droplets and scrubber walls
    iii. Space charge force
    iv. Bipolar attraction between particles and droplets
    v. Image force attraction between particles and droplets / scrubber walls. Particles are also agglomerated in the charger in a precipitation / re-entrance process. Resulting large particles are removed in the scrubber by inertial impaction.Results from laboratory tests, several pilot installations and a full scale (biomass combustion) electrically enhanced scrubber are presented. For fine particles the removal efficiency was observed to be up to 92% for pilot installations and 86% for full scale installation. For pilot installations the removal efficiency depended strongly on particle properties and varied between 65 – 92%.

Session 6B – ESP Fundamentals V (Tuesday, June 27, 2006)

• 6B1 The Technology Development of the COEBP
  • COEBP stands for Compact Electrostatic Baghouse Precipitator. This document tells about the principle of the COEBP and technology development in its application in power industry. This new dedusting method combines the dust-collecting advantages of traditional dedusting – electrostatic and baghouse dedusting. A large quantity of mill dust is first collected by pre-electrostatic field, and then fine mill dust is collected via backstage baghouse dedusting, and hence, realizing the conception of organic combination of electrostatic and baghouse dedusting. It is important originality and a technology development in dedusting principle and method.
• 6B2 Discovery of The Power-saving Principle of Electrostatic Dust Precipitation Using DC Supply
  • This article proves that electrostatic precipitators using DC power supply can save much more electrical energy than those using rectified AC power supply. The discovery of the mechanism of this energy-saving phenomenon lays a theoretical foundation for the use of DC power supply in electrostatic precipitation and greatly promotes a large-scale energy-saving movement in this field.
• 6B3 Novel ESP Model for Impulse Energisation
  • Recently more and more electrostatic precipitator has been upgraded, replacing the traditional DC power supply with impulse energisation. Different types of supply voltage were applied to obtain current impulses for reducing back corona, earning energy saving and better efficiency of precipitation.For the evaluation of the effect of impulse energisation, several numerical models were made using different computational methods. A large number of models calculate ion space charge density distribution assuming continuous ionic current between high voltage and grounded electrodes. This assumption can lead to incorrect result when the “travelling time” of the ions and the time period of the supply voltage (duration of the current impulses and “current free” periods) are in the same range.Our new model for the ion space charge density calculation takes into consideration the rapid, time dependent processes providing more reliable results for the evaluation of the precipitation process. By the help of the new model a detailed analysis of different supply modes can be carried out, to obtain the best possible operation of a given electrostatic precipitator.
• 6B4 The Rectangular Controlling Principle and Method of Automatic Following Control on Dust Density and Wang Meiju in Electrostatic Dust Precipitation
  • This article describes the principle and method of automatic following control on dust density in electrostatic dust precipitation (ESP) that is based on the changing law of dust density in ESP electric field and uses automatic adjustment of output voltage. Rectangular load characteristics for high- voltage power supply source is formed on which the work point located in the vertical line. When dust density changes the work point will timely rises or falls along the vertical line. Experience shows that this method is very simple, efficient and energy saving though there is no special on- line monitoring and control measures used on dust density.

Session 6C – Fabric Filtration I (Tuesday, June 27, 2006)

• 6C1 Fabric Filters For Coal Fired Power Stations
  • Over the last 30 years there has been a significant increase in the use of textiles in coal fired power stations in Australia, Republic of South Africa, China and United States of America. When coal is burnt in a power station approximately 30% of the weight of coal evolves as fly ash particulate emission which must be prevented from passing to the atmosphere.The paper discusses the use of different fibre polymers and yarn types used in filtration media for filter bags. Woven and needled punched fabric structures have developed to achieve low emissions, high air flows and extended life.The paper also discusses the current technology and a perspective on the new emerging trends in fabric filter bags in coal fired power stations.
• 6C2 Experiences in Baghouse Applications after Coal Fired Boilers
  • BWF Envirotec is the world-wide technology leader in industrial dedusting with textile filter materials based on synthetic fibers and scrims. The delivery program comprises a wide range of ready-made filter media, accessories for dust collectors as well as on-site installing and replacements.BWF Envirotec also offers services, such as filter media recommendations, laboratory analysis of filter media and dusts and the simulation of complex dust removal processes. BWF Envirotec filter bags have successfully been applied in numerous power plants. In recent years, there has been an increasing demand because more and more electrostatic precipitators at power plants are replaced by bag houses. Reasons for this are stricter emission laws and the high effectiveness of these systems but also – especially in Europe – because of the necessity to install desulphurization systems in order to control the output on SO2.This means that bag filters in power plants are used to separate dust and where applicable to neutralize harmful acid gases. Here, combustion residue and any harmful substances contained in the additives are separated on the surface of the filter bag, so the filter material is exposed to heavy mechanical, chemical and thermal stress. Consequently, the choice of the appropriate filter medium is of major importance in these applications.In the last decade, BWF Envirotec installed more than 1 Mio m² of filter media for the dedusting of power plants. Our comprehensive experiences in filtration with textile filter bags, as well as some case histories will be presented to the auditors of this conference.
• 6C3 Application of Fabric Filter to Coke Oven
  • To prevent atmospheric diffusion of smoke and dust contained in flue gases, a fabric filter is generally installed in coke ovens in Japan. However, since such dust has a very small particle diameter and consequently is difficult to remove, the pressure loss of the fabric filter increases. This study examined how to decrease the pressure loss of a fabric filter using actual flue gases from a coke oven. The relation between the pressure within the filter cloth and the acceleration during pulse was also reviewed along with the effect of an agent on the pressure loss to find an optimum pulse method. As a result, the specifications of the optimum pulse system at the pulse pressure of 0.6 MPa were clarified together with the effect of an agent. The optimum system was then introduced to an actual system, which is currently operated with the pressure loss kept within the permissible range.
• 6C4 Reverse Gas Baghouse Modelling and Complete Off-Gas System Simulation
  • This paper describes the approach followed by Beier Albany for the design of a negative pressure reverse-gas bag house associated with a Silicon / Ferro Manganese furnace. Each relevant component of the bag house and the gas exhaust system was modeled and used for the compilation of the static model of the entire process. The static model became the baseline for the simulation of the “real time” or transient system operation. These modeling tools are critical for the design of bag houses, assessment of flow, temperature and pressure distribution and optimization of the control philosophy for off-gas systems.

Session 7A – ESP Applications VI (Tuesday, June 27, 2006)

• 7A1 High Frequency Switch Mode Power Supplies For Electrostatic Precipitators Operational And Installation Advantages
  • For over 40 years the most commonly used device to power electrostatic precipitators were standard 50/60 Hz SCR Controller and Transformer/Rectifier sets. However, in the last 6 -7 years a new Power Supply has been introduced to the ESP industry. This Power supply is based on High Frequency Switch mode technology. The new Switch mode Power Supplies are capable of dramatically different performance than the older, 50/60-hertz linear transformer/rectifier sets. As applied to the ESP application, these new power supplies will have a major impact on many aspects of precipitator design, construction, operation, and maintenance.This paper provides an overview of the operational and installation advantages of the PowerPlus; NWL’s switch mode power supply for ESP (electro static precipitator) applications.Recent comparative tests of the two technologies were performed at several Power Companies in the USA. These results will be shared in this paper
• 7A2 Economical Aspects Of Energising Electrostatic Precipitators With High-frequency Switched Power Supplies
  • There is a slow but clear trend to change from conventional mains-frequency operated HVsupply packages for Electrostatic Precipitators to HV-supplies that are high-frequency switched. The main driver for this trend is the easy installation, smooth HVDC and the resulting improved ESP collection efficiency. With more than 1200 high-frequency switched HV supplies in operation today, ALSTOM has gathered a sizeable experience in the use of such equipment.In another paper presented at this conference, Lena Lillieblad et al discuss and compare different ESP upgrade methods to reduce the emission – and mention the high-frequency switched HV-supplies as a “favourite” especially from the cost/achieved result point of view.This paper focuses on the economy in using the high-frequency switched HV-supplies and states that it is always profitable for the end user to use this type of equipment even though the component cost at first sight would seem higher.
• 7A3 Modular Switched Mode Power Supplies – A Way To Solve The Challenges Of Reliability, Output Properties And Cost, Compared To Conventional T/r’s In Esp Applications.
  • One of the conclusions following the ICESP IX was that switched mode power supplies gradually would gain the dominating position as power sources for industrial ESP’s. However, reliability issues, limitation in voltage/power rating and cost competitiveness compared to conventional T/R’s have limited the acceptance of this technology in the industry. As a solution to these obstacles, this paper describes a new and innovative design approach by presenting a modular switched mode power supply concept, the APP ModuPowerTM.Development of the ModuPowerTM concept is based on more than 8 years of experience in development and delivery of switched mode power supplies to industrial plasma applications. It is a true modular concept where output voltage is decided by connecting the high voltage modules in series to the desired level, while output current capacity is decided by connecting modules in parallel. The modular concept is made possible by implementing a novel, patented high voltage transformer design, allowing serial connection of transformers without serious power/efficiency loss. In addition, low parasitics in the transformer, allows simplified switching techniques resulting in simple building blocks for the modular concept.The modular approach decomposes the challenge of high voltages and high power ratings into manageable entities, while offering output voltages up to 120 kV and in principle, unlimited output power ratings. Furthermore, the modular concept is well suited for implementing redundancy inside the power supply, resulting in a fault tolerant system, and thereby increased reliability. Simple and efficient building blocks in a modular configuration, result in a small and cost competitive power solution compared to conventional power sources.Through the development of ModuPowerTM, APP aim at solving the major objections towards using switched mode power supplies in ESP applications, which hopefully moves us closer to the long announced paradigm shift in this industry.

Session 7B – ESP Fundamentals VI (Tuesday, June 27, 2006)

• 7B1 Application of Modern ESP Models to Low Sulphur, High-Ash Power Station Conditions
  • Modern electro-hydrodynamic models of electrostatic precipitator behaviour are now publicly available and have been widely used in the U.S.A., Europe and the NIS. The best known of the new models is ESPVI, developed by the US EPA, which simulates the precipitator on an element basis to give an extensive amount of operating information. The performance of this model with Southern Hemisphere coal ashes has not previously been reported, but is of interest throughout the world due to the large quantity of traded steaming coal from this region.A complete electrical, mechanical and performance study of a precipitator collecting ash from a utility burning Central Queensland coal was used to test the ability of the ESPVI model to predict actual operating conditions. The study was undertaken before and after a major overhaul, enabling both new and deteriorated conditions to be modeled.Further studies of other regional precipitators were undertaken to compare the results amongst installations with widely varying ash content and elemental analysis. The results of these studies are presented to allow users to apply the models to their own installations for performance prediction when considering remedial or upgrade work.
• 7B2 Development of an Industrial Model of Rapping – Effect on the Collecting Efficiency
  • The rapping process is not yet well understood for two main reasons : on the one hand the objectives of the research have been focused for many years on a empirical optimisation of rapping, the knowledge of generation and evolution of the layer was considering as less significant, on the other hand the evolution of the dust layer is difficult to reproduce in a laboratory physical model. The experimental study of the mass balance in an industrial esp pilot provided precious data and made the development of the model possible. It has been compared with good agreement with an industrial esp test in a 500MW power plant. The model of rapping plates has been developed and integrated in the new version of the EDF-IRS software ORCHIDEE to help the plant staff to optimise their rapping sequences. ORCHIDEE is a user friendly software and we succeed to integrate the rapping model with only geometrical and operational data like the different times of rapping operation, the variation of these times influences the layer thickness on the plate and finally the collecting efficiency.
• 7B3 A Numerical Model of a Wire-Plate Electrostatic Precipitator under Electrohydrodynamic Flow Conditions
  • A new numerical model for the electric field and gas flow in a wire-plate electrostatic precipitator with a single corona wire is presented. The electrical conditions in the precipitator channel are simulated by solving a full two-dimensional single-species model of the electric corona discharge. The electric field and space charge density are predicted by simultaneously solving the electric field and charge transport equations using a hybrid Finite Element – Method of Characteristics numerical algorithm. The electric Coulomb force generates the secondary electrohydrodynamic flow of air, which modifies the main gas flow. This part is simulated by solving the Navier-Stokes equation, using the FLUENT – commercial CFD computer software. The numerical results for the electric field distribution, ion density, and flow pattern are shown for different values of non-dimensional numbers characterizing the process. The flow pattern generated by the EHD effect is asymmetric with respect of the transverse axis of ESP and generation of the forward wake can be observed, if the non-dimensional Ehd number is larger than 1710.

Session 7C – Fabric Filtration II (Tuesday, June 27, 2006)

• 7C1 Cost Comparisons between Electrostatic Precipitators and Pulse Jet Fabric Filters and Inherent Challenges of both Technologies at ESKOM’S 6 X 600 MW Duvha Power Station
  • 3 600 Mw Duvha Power Station situated near Witbank in Mphumalanga Province presents a unique opportunity to make a direct comparison of operating and maintenance costs between electrostatic precipitators (ESP’s) and retrofitted pulse jet fabric filters (PJFF’s). Units 1 to 3 have the ABB Flakt design PJFF’s and Units 4 to 6 have the originally installed Lurgi design ESP’s with 5 field 141 m2/m3/s specific collecting area (SCA). These ESP’s have subsequently been retrofitted with sulphur trioxide flue gas conditioning (SO3 FGC). This comparison is particularly interesting when viewed in the context of the Legislation which compels either a load reduction or an outage in order to avoid contravening particulate emission Limits and this at a time when there is little reserve margin on the total Eskom System. The trade-off between operational costs and the ability to generate MW’s can be complex.This paper will briefly review some of the early problems experienced with the PJFF’s and measures taken to increase bag life, ultimately resulting in a change to a more expensive fabric type. It also reviews some of the day by day operational demands of the ESP’s.
• 7C2 Colorado Springs Utilities Improves Fabric Filter Performance by Installing Expanded PTFE Membrane Filter Bags
  • Actual operating results have been used to empirically determine the relationship between fabric filter (baghouse) differential pressure and stack gas flow in a reverse gas cleaned fabric filter. Assumptions are made that the tubesheet pressure drop is the sum of the pressure loss across the filter media and the dust cake. The dust cake is comprised of a component that remains on the bag after cleaning and a removable component that accumulates between cleaning cycles. The component that accumulates between cleaning is proportionate to the inlet dust concentration, the filter velocity and the time between cleaning. This relationship was examined with conventional fiberglass filter bags and with filter bags that have an ePTFE membrane laminated to the woven fiberglass. On average, the results show a 41% decrease in fabric filter drag that allowed actual stack gas flow to increase by 5% and baghouse pressure differential to decrease by 39%. Results suggest the lower drag is attributable to improved ash removal from the bag during cleaning and not due to lower resistance through the filter media itself. Maximum electric power generation increased by 2.8% during the peak summer demand period due to the higher gas flow achieved with the ePTFE membrane bags.

Session 8A – ESP Applications VII (Tuesday, June 27, 2006)

• 8A1 Performance Improvement of Electrostatic Precipitator: Some Experimental Studies
  • Emissions standards are becoming more stringer, as a result new retrofit/technique are being applied in the existing power plant in India. Electrostatic Precipitators (ESP) are used to control fly ash emitting from the boilers of the power plants. The coal burned in power plants in India to generate the power are characterized by low calorific value (3500-4500) Kcal/Kg., and high ash content (35-45) %. Thus compared to U.S. and European coals, Indian coal generate about 6 to 7 times more ash for collection for similar electricity generation. Besides, low sulfur content (<0.5), results in the resistivity of fly ash being 100-1000 times higher than that generated elsewhere. Thus ESPs in India, despite being much larger, have lower collection efficiencies than the ESPs in U.S/Europe. In this paper we discuss some methods which are being applied in different power plants in India to improve the collection efficiencies of ESP.The methods, which have met with success, are (a) Pulse charging of ESP unit, (b) Flue gas conditioning by water fogging and ammonia, and (c) coal ash conditioning with sodium salt before feeding to boiler. In some case additional ESP was put in series with the existing one thereby, increasing the total collection area. The paper describes the experiments and analyses the results obtained.
• 8A2 Upgrade Technologies for Electrostatic Precipitators
  • Electrostatic precipitators (ESP’s) are commonly used for collection of particles in power plants and industrial applications. There are many ESP’s around the world not meeting today’s requirements due to aging, process changes and more stringent regulations for emission limits. Before ESP performance improvements can be considered, measures must be taken to ensure that the equipment is mechanically sound. Once this is accomplished there are various upgrade technologies available to improve the ESP performance. In order to choose the most appropriate upgrading technology it is necessary to have a good knowledge about the site-specific conditions. Measures can be taken to:
    · Avoid or reduce the effect of high resistivity dust
    · Reduce re-entrainment of dust caused by rapping or high gas velocity
    · Change the mechanical ESP design by replacing internals and/ or rapping system
    · Upgrade the ESP energy supply and control systems
    · Optimize gas distribution and reduce sneakage
    · Increase the ESP size
    · Change the particle size distribution with agglomeration technologiesIn this paper different upgrading techniques are described and compared both from a technical and economical point of view. A modern ESP control system is often a cost-effective method with a significant potential to reduce both emissions and power consumption especially at high resistivity dust conditions.Exchange of old transformer/ rectifiers (T/R’s) to high-frequency power converters have been successful in reducing the effect of corona quenching and allowing a higher T/R power input when severe space charge conditions prevails at high dust loads. Significant reductions in emissions have been observed.

Session 8B – ESP Fundamentals VII (Tuesday, June 27, 2006)

• 8B1 Investigations on Fly Ash Resistivity: Development of Empirical Relations Based on Experimental Measurement
  • Fly ash resistivity is a single parameter which has got significant impact over sizing and performance of Electrostatic Precipitator (ESP) in coal based thermal power plants. A fly ash resistivity measurement facility has been set up at IIT Delhi with the support of National Energy Technology Laboratory (NETL), USA and USAID-India. The fly ash samples from different power plant are being collected by CenPEEP, NTPC and supplied to IIT Delhi for measurements. The experiments were conducted for the measurements of electrical resistivity over a wide range of temperatures (90-455) 0C as per IEEE standards. Around 250 samples obtained from different power plants in India, have been tested. Empirical relations developed by Bickelhaupt, which are based on the chemical composition of fly ash for calculating the electrical resistivity are used to calculate as theoretical value for given experimental conditions. Comparisons between fly ash resistivity obtained from experiments and theoretical values show significant differences between the two values especially at low temperatures (90-160 0C), where surface conduction is important. This is due to the different chemical compositions of ash/fly ash obtained from the coals used in power plants in India and USA. New empirical relations based on chemical compositions, generated in typical Indian power plants have been developed to calculate electrical resistivity at the temperature and moisture corresponding to actual conditions to ESP. These relations provide better agreements with experimental values.
• 8B2 Experimental and Calculated Values of Migration Velocity as a Parameter of Precipitation Process in Electrostatic Precipitators
  • This paper presents results of experimental studies of fly-ash particles migration velocity obtained in a horizontal electrostatic precipitator (ESP) physical model.The particle migration velocities were recorded and measured by means of photo camera visualization of particle movement trajectories and the ESP model performance effectiveness. Tests were carried out with different parameters of electrical field, different kinds of fly ash and particle size distribution, and for many types of discharge electrode shapes. Substantial influences of discharge electrode shape on the measured migration velocities were found.The test results shown as graphs and tables, confirm the possibility to utilize the physical ESP model results in the ESP design processes as well as for selection of precipitation process adequate discharge electrodes.

Session 8C – Fabric Filtration III (Tuesday, June 27, 2006)

• 8C1 Managing Bag Shrinkage in Low Temperature Fabric Filter Plants
  • Low temperature fabric filter plants normally utilize bags manufactured from Polyacrylonitrile (PAN). Although these bags are cheaper than high temperature bags, manufactured from Polyphenylenesulphide (PPS), they are prone to shrinkage.Shrinkage in a fabric filter plant is problematic in the sense that it not only affects the performance of the bags, but indeed, of the whole gas cleaning system. Some of the areas affected are permeability, cleanability and strength.The shrinkage can be chemical of nature. This is related to the cyclisation of the PAN fibers due to heat or chemical attack. The shrinkage could also be physical of nature, which means the shrinkage is caused by the elastic memory of the fibers and stresses induced in the felt during manufacturing.

    Heat setting of the fabric is very important and differences of parameters during the heat setting process are responsible for differences in the shrinkage behaviour of adjacent bags in the same bag house, constructed of the same fibre and in the same needling loom.

    This paper deals with the reasons for bag shrinkage and how it could be managed.

• 8C2 Selection Criteria of PPS and PPS/PI Blends for Use in Power Station Applications
  • The use of PPS in CFBs is not new, in fact the since the introduction of the original fibre Ryton ® introduced by Phillips Co many thousands of filter bags have been installed and operated satisfactorily.Today’s challenges are however substantially more demanding than they were 20 or even 10 years ago. Power Station Managers are not happy with bag lifetimes of two or three years as was the case on many of the earlier installations, the quest today is for lifetimes to meet with Power Station GO’s. This can mean bag lifetimes of > 48000hrs. This for a textile can be a huge demand, it is achievable but in turn Power Station Managers must also understand the factors which can affect the fabrics lifetime. These factors take three basic forms, chemical, thermal and physical.The PPS fibre performance is the first issue and this is examined relative to the flue gas analysis and the operating temperatures inside the bag filter. Once established that the PPS fibre can withstand the chemical/thermal conditions then the construction of the needlefelt is taken into consideration. To achieve long lifetimes it is necessary to design a high efficiency needlefelt which would require less cleaning cycles than a normal PPS felt offers. These designs can take two basic forms. Firstly by applying a PTFE coating and secondly by blending PI fibres into the surface structure of the needlefelt.

    Today we have the possibility to compare the standard PPS filter bag with the more sophisticated designs using a filter test rig according to VDI/DIN 3926. The rig allows us to compare the filtration performance of different fabrics under defined conditions.

    The conclusion of the testing allows us to have more confidence in the selection of the correct filter media. We must however combine the gas data and the ash data to be able to make the correct selection. Laboratory tests can of course only be used as indicators the experience gathered in from actual applications is and always will be the most effective criteria for fabric selection. Our experience in the field is extensive and from a wide reference list we highlight two interesting installations.

    Gutsche introduced the first PTFE coated fabrics and the first blended fabrics in the mid 80s, the PTFE coated PPS has been successfully installed in many earlier stations such as Rooiwal and Kelvin Power Stations in South Africa, the first blends also being installed at Arnot Power Station in South Africa and Hohot Power Station in China.

Session 9A – ESP Applications VIII (Wednesday, June 27, 2006)

• 9A1 Improvement of Reliability for Moving Electrode type Electrostatic Precipitator
  • A moving electrode type electrostatic precipitator, which is equipped with brushes to remove dust from the moving collecting plate surface, is effective in collecting high resistivity dust. The collecting plate of the moving electrode type electrostatic precipitator is divided into strips, coupled with chains and moved by driving wheels. In Japan, 51 units of the moving electrode type electrostatic precipitator have been manufactured since 1979.For the moving electrode type electrostatic precipitator, an important factor is to improve the reliability of the moving component parts such as the movable collecting plate element, the rotating brush, the chain and so on. These parts are refined and the life spans of these parts are evaluated by actual operation results.There is an upper limit of inlet dust density for the moving electrode type electrostatic precipitator. Fixed electrode sections are commonly combined as a pre-collector to reduce dust density at a moving electrode section. A collection performance equation has been studied using the combination of fixed electrode sections and a moving electrode section.
• 9A2 The Application of Magnetically Enhanced Corona Pre-charging Technology for the Electrostatic Enhanced Filter
  • In this paper, experimental investigations on discharge characteristics of magnetically enhanced corona discharges for the purpose of capturing fine aerosol particles are presented. The discharge mechanism during such a process is analyzed. The effects of magnetic enhancement under different magnet flux densities and in positive or negative corona discharges were experimentally compared. The magnetically enhanced effects in different inter-electrode regions were studied. Experimental results demonstrated that magnetic field can efficiently increase the concentrations of both the negative ions and the free electrons under negative corona discharging. The dominant mechanism of magnetic enhancement in corona discharges is that the Larmor precessions of free electrons enhance the ionizations of the gas molecules near the discharge electrode. A reasonable configuration of magnetic enhancement for enhancing corona discharge was formed by permanent magnets with a local strong magnetic field near the discharge electrode. A magnetically enhanced negative corona (MNC) pre-charger was assembled in front of an electrostatic enhancement filter. The influence of the MNC pre-charger on the efficiencies of an electrostatic enhancement filter was measured and compared with that of a conventional corona pre-charger. The free electron charging mechanism of the MNC pre-charger was preliminarily analyzed. The new pre-charging technique is promising for capturing fine aerosol particles in electrostatic enhancement filters or electrostatic precipitators.
• 9A3 Laboratory Research on Collection of Particles Reentrained from Corona Electrode
  • At the exit of electrostatic precipitator, among the escaped particles there have not only neutralized particles, but also particles that remaining negative and positive charges. Sometimes positively charged particles can account for 30%~50% of the total particles escaped. They are formed probably from the reentrainment by corona electrode rapping or from back corona effects. In view of this phenomena, for strengthen the corona electrode capability of capturing positively charged particles; new types of corona electrodes were investigated. It has multi-function of corona discharge, reducing back corona, prevent reentrainment and collect the positively charged particles.Different types and geometries of corona electrodes were proposed; all of them were featured to add a channel shaped wind buffer, which has the same voltage with the corona wire and located between subsequent corona wires. These buffers can reduce gas flow scouring reentrainments, collect positively charged particles and restrain back corona by electrostatic shielding effect. Bench scale laboratory tests were made to explore their discharging characteristics, current density distributions, etc. Two- dimension flow mathematics models were set up and boundary conditions were confirmed. Using k-eequation, the pure air turbulent flow fields of corona electrodes with and without wind buffers were studied.Tests shown the shielding benefits of both reducing the gas flow scouring and back corona were more remarkable when the distance between buffer and corona wire became closer. But if too small, the over reducing of corona discharge and breakdown voltage will give reverse effects. By optimizing this distance, a steady, high performance operation can be gotten. Laboratory experiments give the recommended distance was 150mm and the recommended buffer width was 60mm.Pilot and industrial tests of likely shielded corona systems also revealed the same beneficial effects.

Session 9B – ESP Fundamentals VIII (Wednesday, June 27, 2006)

• 9B1 Assessing the Significance of the Indigo Aerodynamic Agglomeration Technology Using MIE/LIF Laser Diagnostics
  • A detailed laser diagnostic study has been performed to determine whether aerodynamic mechanisms may be exploited to promote significant agglomeration of fine particles to larger ones, with a view to enhancing the capture of fine and ultra-fine particles in conventional particle collection devices, such as Electrostatic Precipitators. This study was prompted by a series of findings from full-scale trials of a aerodynamic mixing device by Indigo Technologies, which led them to patent technology based on the aerodynamic agglomeration processes. The study assessed the extent to which the patented Indigo Agglomerator technology achieved an increase in the number collisions between PM2.5 droplets and PM10-50 droplets and, in turn, in the capture of the small by the large droplets using aerodynamic processes.The studies were conducted in the potential core region of a large unconfined jet produced by a wind tunnel contraction. The small water droplets were generated with a TSI atomiser and marked with concentrated Rhodamine 6G dye to allow them to be discriminated from the large droplets. The large droplets were generated by a commercial fine-spray nozzle and were not dyed. Two cameras were used, one to image the fluorescent signal from the fine droplets only, and the other to image the Mie scattered signal from both droplets. The measurements were performed for arrangements with and without the aerodynamic mixing device in place, and with one or both of the droplet streams introduced into the flow. The fluorescent signal from the small droplets is found to decrease significantly, but only for the case where both the large and small droplets are present in the flow along with the aerodynamic device. This clearly shows that the aerodynamic device used in the Indigo Agglomerator technology greatly increases the number of collisions between large and small particles, providing an explanation for the increased capture efficiency found in the industrial-scale Indigo Agglomerator technology.
• 9B2 Properties, Charging Processes and Depositions of Particles in Electrostatic Filtration Systems
  • Due to a growing environmental awareness the application of high voltages in environmental technology, in particular of high d.c. voltages, is becoming more and more important. The application this paper deals with is the process of electrostatic air filtration.Electrostatic filters share one common feature: particles are charged and attracted by electrical forces; they are led to a collecting electrode. This separation of charged particles in electrostatic fields represents a simple and very efficient possibility of filtering the air. The field of application of electrostatic filters comprises medical engineering, tunnel exhaust cleaning, gas cleaning in industrial plants and room air cleaning. A new interesting field is the particle filtering of diesel exhaust fumes, where different methods and technologies are applied. Therefore this paper deals with basics of particle qualities and the qualities of bioaerosols. Viruses and fungus cultures are presented as well. A further field this paper deals with is the charging process and deposition of particles in electrostatic filtration systems, referring to the size, and electrical agility and health risk of particles.
• 9B3 Experimental Study on Electrostatic Precipitation with Spraying Corona Discharges
  • A simulative device was employed. The corona onset saturation, the V-I characteristics and the precipitation efficiency were researched and compared between spraying negative corona discharges and dry negative corona discharges. The experiments shown the precipitation efficiency of spraying negative corona discharges reached to 28% higher than that of dry corona discharge (from 78.2% to 84.2%), under the conditions of the same high voltage and gas flow rate. The new discharge characteristics and precipitation principle were analyzed and discussed. The comparing between spraying negative corona discharges and dry negative ones shown that spraying negative corona discharge is more suitable for removal of particle contamination. The spreading corona plasma of spraying positive corona discharges plays a more important role for purifying the spraying circulating water.

Session 9C – ESP Applications IX (Wednesday, June 27, 2006)

• 9C1 Fabric Filter Retrofits an Electrostatic Precipitator Upgrade Technology
  • Increasingly more stringent emission limits have required many electricity-generating Utilities to upgrade existing electrostatic precipitators (ESP’s). Design efficiencies of 2 and 3 field ESP’s built in the 1960‘s and 1970’s ranged from 96% to 98% and were adequate then. One of their primary functions was to reduce ash erosion of the induced draught fans.Retrofitting pulse jet fabric filters into these small casings have provided a cost effective solution to Eskom. These fabric filters require a small “footprint” and emissions of less than 50 mg/Sm3 are sustainable and not as dependant on coal quality and up-stream conditions as is the case with ESP’s. This is an important consideration for Eskom because legislation requires load losses or unit shutdown prior to contravening emission limits. A total of 7 700 MW of Eskom’s plant have been or are presently being converted to fabric filters at 5 power stations on 31 boilers.This paper provides an overview of one of these projects presently in progress at Camden power station on 6 x 200MW boilers. These fabric filters have a unique 4 cell design allowing for on- load maintenance, bag changes and operating flexibility. Lessons learnt from previous projects and improvement in fabric material and construction through research will ensure that these advanced fabric filters are successful.
• 9C2 Retrofitting Fabric Filter Plants into Small Electrostatic Precipitator Casings
  • Electrostatic precipitators (ESP) built in the 20th century were suitable for the emission requirements of the time, but as environmental legislation and awareness increased, the performance of these precipitators were sometimes no longer compliant with increasingly stringent legislative requirements. Often these precipitators were two or three-field devices and it is difficult to improve the performance of such small-footprint plants to current requirements.A viable option for improving the efficiency of these emission control devices is to retrofit pulse jet fabric filters into the old and small ESP casings. Such a project has recently been completed at Hendrina power station, South Africa.The plant was originally equipped with ESP’s for gas cleaning, but these were recently replaced with fabric filter plants (FFP), retrofitted into the two and three field ESP casings. The project was executed in three phases, starting in 1994. It was completed in 2004.

    This paper will describe the original performance of the ESP’s, the performance of the FFP’s, the factors influencing the decision to improve the plant, and what criteria the new / refurbished plant had to meet.

• 9C3 Selection Criteria Of Pps And Pps/pi Blends For Use In Power Station Applications
  • The use of PPS in CFBs is not new, in fact the since the introduction of the original fibre Ryton ® introduced by Phillips Co many thousands of filter bags have been installed and operated satisfactorily.Today’s challenges are however substantially more demanding than they were 20 or even 10 years ago. Power Station Managers are not happy with bag lifetimes of two or three years as was the case on many of the earlier installations, the quest today is for lifetimes to meet with Power Station GO’s. This can mean bag lifetimes of > 48000hrs. This for a textile can be a huge demand, it is achievable but in turn Power Station Managers must also understand the factors which can affect the fabrics lifetime. These factors take three basic forms, chemical, thermal and physical.The PPS fibre performance is the first issue and this is examined relative to the flue gas analysis and the operating temperatures inside the bag filter. Once established that the PPS fibre can withstand the chemical/thermal conditions then the construction of the needlefelt is taken into consideration. To achieve long lifetimes it is necessary to design a high efficiency needlefelt which would require less cleaning cycles than a normal PPS felt offers. These designs can take two basic forms. Firstly by applying a PTFE coating and secondly by blending PI fibres into the surface structure of the needlefelt.

    Today we have the possibility to compare the standard PPS filter bag with the more sophisticated designs using a filter test rig according to VDI/DIN 3926. The rig allows us to compare the filtration performance of different fabrics under defined conditions.

    The conclusion of the testing allows us to have more confidence in the selection of the correct filter media. We must however combine the gas data and the ash data to be able to make the correct selection. Laboratory tests can of course only be used as indicators the experience gathered in from actual applications is and always will be the most effective criteria for fabric selection. Our experience in the field is extensive and from a wide reference list we highlight two interesting installations.

    Gutsche introduced the first PTFE coated fabrics and the first blended fabrics in the mid 80s, the PTFE coated PPS has been successfully installed in many earlier stations such as Rooiwal and Kelvin Power Stations in South Africa, the first blends also being installed at Arnot Power Station in South Africa and Hohot Power Station in China.

Session 10A – ESP Applications X (Wednesday, June 27, 2006)

• 10A1 SO3 Flow Biasing, an Engineered Approach
  • One of the major problems that have been encountered in the attempts to perform SO3 conditioning of multiple ESP (electrostatic precipitator) path units is the distribution of SO3 gas to the path where it is needed in the correct quantities. In cases where a Lungstrum type rotating air heater is used, where environmental conditions such as ambient air temperature are affecting duct temperature or when uneven distribution of ash causes an imbalance in loading, how can you deliver the correct amount of SO3 to the paths in need of additional conditioning without over conditioning the others? Several approaches have been tried such as valves, remote converters or even orifice plates in the SO3 lines. All of these methods have short comings when trying to adjust flow to the various ESP paths.
• 10A2 A New Type Field Test Instrument for Specific Resistivity of Fly Ash
  • The probe of this instrument can be inserted into the flue directly for testing the specific resistivity of fly ash. It adopts the ceramic filtration catcher and iso-speed sampling based on static pressure balance technique with parallel short-tube. The collection efficiency of ceramic filtration catcher (h) can reach even exceed 99.9%, and the error of sampling in different velocities is less than or equal to 5%. All these make the sameness between samples and the actual fly ash in many facets, including size distribution, carbon content, element compositions, etc. The coefficient of optimizing ringed electrode for concentric cirques k is 14.6, which can adapt all kinds of fly ash whose specific resistivity is in the range from 104 to 1013W× cm. In addition, the ceramic filtration catcher made of white corundum powder can endure high temperature, high voltage, and acid cauterization. So this test instrument can work well under the conditions in which the flue temperature is from room temperature to 300oC and in the caustic gas. Ceramic filtration catcher also has many excellences, such as avoiding disassembly, cleaning ash easily, repeating use for long time. This instrument has obtained the invention patent in China and applied widely in the domestic range.

Session 10B – New ESP Technologies I (Wednesday, June 27, 2006)

• 10B1 Development of Electrostatic Precipitator for Road Tunnel
  • Since Japan has a geographical feature with a lot of mountains, many long tunnels such as exceeding 2 km have been constructed. In the case of long tunnel, problem of insufficient visibility is sometimes caused by large vehicles of diesel engine. To keep driver’s visibility, electrostatic precipitator (ESP) has been installed in by-pass tunnel of the main tunnel. Furthermore, not only in mountainous area but also in metropolitan and suburb areas, many tunnels have been constructed to avoid traffic congestion in recent years and ESP has been installed in ventilation tower in order to reduce external emissions as well. ESP installed in ventilation tower is required small installation space and large volume air flow rate.Based on many experiences and technologies on ESP for industrial applications, we have developed the technology of new (spiked) plate type ESP for road tunnel requirement instead of wire type ESP which is often adopted in earlier ESP for road tunnel or in air purifier installed in air conditioner.

    This paper describes the introduction of new (spiked) plate type ESP and its application for road tunnel in Japan. Furthermore, ozone (O3) reduction method using the intermittent energization of high frequency power supply is introduced as well.

• 10B2 High Velocity Electrostatic Precipitator for Road Tunnel
  • Electrostatic Precipitator (ESP) is applied for road tunnel. ESP can remove SPM (Suspended Particulate Matter) in the air using Corona Discharge Plasma. ESP for road tunnel is used to deliver visibility inside the road tunnel and to preserve environment around opening from the road tunnel.The tunnel owner wants to reduce the tunnel auxiliary space like ESP because the civil cost of road tunnel is very expensive. So that ESP is required to treat very high air velocity and large air volume in this limited space. In Japan, the first standard ESP is determined to treat air volume is 3.75 m3/s, 7m/s air flow velocity inside the ESP. The latest one is determined to treat 5 m3/s, 9m/s.

    In recent years, the requirement of the environmental preservation around opening from the road tunnel is so strong that ESP is applied to some aged tunnel ventilation stations.

    To apply ESP in aged tunnel ventilation, the space for ESP is extremely limited that it has to treat larger air volume and higher air velocity are required. We developed innovative ESP which is used saw edge electrode with zigzag edges and it realizes 7.2 m3/s, 13m/s. This ESP is installed to some road tunnels and now, actually operating.

    In this paper, we describe the characteristic of the Corona Discharge Plasma using this saw edge electrode with zigzag and show the actual applied ESP in road tunnel.

Session 11A – ESP Applications X (Wednesday, June 27, 2006)

• 11A1 SO3 The Bi-Corona® – ESP – A New Development to Enhance
  • In the search for the best way to improve the efficiency of electrostatic precipitators (ESP’s) and especially to increase the rate of fine particle removal, conflicts between some influencing physical parameters are encountered over and over again. Obviously, the optimal solution should take into account the conflict between the physical effects on particle charging and those on the particle collection at the plate electrodes: Efficient charging of the particles requires a strong gas ionization (corona) and a high current flow. In contrast, a strong electrical field is necessary for the collection of the particles. A high current flow is not required here. These different requirements for the control of the charging and collecting effects are what we call the “ESP conflict”. The technical solution developed by Balcke-Duerr to solve this conflict is the “Bi-Corona Technology (BCT)”. This technology is based on a patent which was first filed during the authors earlier professional time with Walther&Cie in Cologne, Germany and which was first introduced on the ICESP VII in 1998 in Kyongju, Korea (1). The special design of the discharge electrodes and the matched construction of the collecting electrodes make it possible to meet the different requirements of highly effective particle charging and collecting. The principle is to divide each electrical field of the ESP into several different ionization and collection zones (Bi-Corona Principle). The Balcke-Duerr Bi- Corona System was developed for new ESP’s and for retrofitting existing ESP’s. The presentation will show some details of the patented design, results and measurement data of converted ESP’s in comparison to conventional units, as well as preliminary laboratory tests.
• 11A2 Investigation of an ESP Based on ERDEC Design after an Oil Fired Boiler
  • The by far most commonly used type of electrostatic precipitator for both power and industrial applications is the conventional parallel plate duct type ESP. In the early 1990’s a novel variant of ESP electrode systems, resulting in a completely different layout of the internals, was developed in Japan. This so called ERDEC design has alternating collecting and discharge electrodes in the gas direction with the discharge electrodes having a multitude of extremely sharp corona points while the collecting plates are short and densely spaced. A number of these ESP’s have previously been installed in Japan for some smaller industrial applications and have shown satisfactory performances. These units have worked at smaller volumes and lower treatment times of the gas than is usually the case for conventional ESP’s, hence implying a cost efficient design.

    This paper describes the installation and testing of a two-field ESP based on ERDEC design after a 12 MWth oil fired auxiliary boiler at Karlshamn Kraft AB in Sweden. The oil has a sulphur content of 2.1 % and gives a very low inlet particulate loading with a large fine fraction. The corresponding outlet particulate emissions after the ESP have been measured at 1-2 mg/Nm3. Also low sulphur oil, which gave much higher inlet dust concentrations of mainly unburnt content, was investigated. The emission for the low sulphur dust was dominated by dust re-entrainment during rapping. Rapping losses are known to be a major problem for ESP’s dealing with large unburnt particles from oil firing. The main findings are that the ERDEC design performs well from a precipitator point of view, and that the reduced footprint and casing volume that could be achieved deserves further attention.

Session 11B – New ESP Technologies II (Wednesday, June 27, 2006)

• 11B1 Efficiency Improvements on Large Industrial Electrostatic Precipitators with IGBT Inverter Technology
  • By increasing the precipitator efficiency the stack emissions and operating costs can be reduced. During the operation of a precipitator different load and dust conditions need to be handled. In many applications fuel needs to be switched to lower sulfur contents leading to lower electrical conductivity of the dust. Often, precipitators are to be operated outside their design data. Due to the high cost of a mechanical precipitator extension, the preferred solution is upgrading the high voltage power supply to achieve the regulating authority’s required stack emission limit. Large industrial precipitators with multiple fields can be operated with different types of high voltage supplies for optimum precipitator performance and operation. IGBT inverter based high voltage supplies used in the inlet fields can increase the average corona power significantly. Additionally, the fast flashover reaction helps to increase the average voltage even with high flashover rates. Thus the particle charging and the flashover frequency can be optimized, and particle collecting will be improved even in the following fields. Fine particles can be treated by short pulses generated by IGBT based technology in the outlet fields. Due to the networking features of the different types of high voltage power supplies the total performance and power consumption of a precipitator can be continuously optimized depending on the operation conditions.

    IGBT inverters can be designed in resonant and hard-switching modes. The details of both types will be discussed and the higher flexibility of the hard-switching will be shown.

    Furthermore, the power consumption of large precipitator needs to be considered, particularly, in large IGBT inverter installations. With power management huge power savings are possible while the stack emissions are kept low. Therefore, the precipitator efficiency could be significantly improved by achieving both, lower emissions and lower power consumption.

• 11B2 Development of High-Power, High-Frequency and High-Voltage Power Supply System for Electrostatic Precipitator
  • In this document, the design principle is analyzed for the new type of high-power, highfrequency and high-voltage power supply system for ESP which is developed independently by Longking; the advantages of using the technical solution of series resonance soft switching are explained; the experience in developing power supply for ESP for many years is applied to resolve various key technical issues; all kinds of functions to improve the dust collection efficiency are designed completely. On-site application conditions are discussed preliminarily in this document.

Session 12A – ESP Applications X (Wednesday, June 27, 2006)

• 12A1 Indigo Particle Agglomerators Reduce Emissions and Opacity on Coal-Fired Boilers in The US: A Proven Technology
  • The Indigo Agglomerator has been installed at five power stations worldwide, providing a significant improvement in electrostatic precipitator performance that has proven consistent over time and a wide range of coals. The five power stations utilize a range of plant designs including European and American design electrostatic precipitators and various boiler combustion arrangements. The coals burned include a range of Australian, Columbian, and United States coals. By providing a reduction in mass emissions of 30% to 60% and a reduction in Opacity of 50% to over 80% across this range of operating conditions and over a period in excess of three years, the Indigo Agglomerator can now be considered as a proven technology for reducing emissions from electrostatic precipitators and the corresponding stack Opacity.

    There are three full scale Indigo Agglomerators in operation on coal fired boilers in the US. This paper focuses on the reductio n of total particulate matter (PM), PM 2.5 (PM less than 2.5 um in diameter), and visible emissions (Opacity) on the three US installations.

• 12A2 Development of Smoke Eliminator Adapting Electrostatic Technology
  • In case of fire, maintaining visibility is very important for people to find the refuge at the first fire stage. Especially, fire at underground levels causes smoke flowing to the same direction as the passage to the refuge, so that the countermeasures to maintain visibility, such as ventilation system, should be equipped. However, many old buildings may not allow additional duct space for providing enough ventilation.

    In such cases, a fire smoke eliminator can assist the safety refuge even if ventilation may not be enough provided. For this purpose, a new concept of smoke eliminator using electrostatic technology is proposed, and an experimental model test has been performed.

    Since the smoke eliminator is operated only under the emergency condition, the size of the eliminator is required to be compact. However, in case of fire, the eliminator should treat huge amount of smoke gas having dense and fine particulates.

    For satisfying with the above function and effectively eliminating smoke, a new technology using ionic wind accompanied with corona discharge is applied.

    The test result of compact sized model shows very high performance for both cases, white smoke mainly consisting of mist and black smoke of unburned carbon. For white smoke with 0.5 micro meters of particulate mean-diameter, the collecting efficiency exceeds 98% when the retention time is less than 0.5 seconds.

• 12A3 Technical and Economical Comparisons between Different Kinds of Materials and Different Geometries for Electrostatic Precipitator Insulators
  • Accompanying the fast development of power, cement and iron/steel industries recently, China have produced huge quantity of precipitators and its insulators. Different kinds of material were used for insulators, such as common electrical porcelain, high strength electrical porcelain, quartz (silicon glass), high polymer and high alumina porcelain, etc. A lot of successful and non-successful experiences were encountered. Of course there have different suitable material and geometrical choices for different industrial processes, yet it seemed for the same process there may have some different material requirements between European type and American type precipitators mainly because of their different type of electrode rapping.

    This paper summarized the Chinese experiences and comparisons of material selection and insulator geometries for different processes and precipitators both technically and economically.

Session 12B – 12B New ESP Technologies III (Wednesday, June 27, 2006)

• 12B1 Sieving Electrostatic Precipitator
  • The paper describes so-called Sieving Electrostatic Precipitator (SEP) suitable for efficient and cost-effective cleaning of polluted gases of both large and ultra fine particulates in a very broad temperature range. Some of the laboratory-pilot-test results are discussed. The paper also describes the ongoing research project jointly funded by the Ohio Coal Development Office (OCDO), American Electric Power (AEP), Electric Power Research Institute (EPRI), Ohio University (OU) and PECO Inc. related to design, building and testing of a large-size pilot SEP to be built as a part of slipstream at the AEP’s Conesville, Ohio power plant.

    In the SEP the particulate-laden gas is passed through a set of closely packed and charged fine wire screens. Depending on the application, the screens can have the same or alternating polarity– the former configuration being a more compact and cost-effective solution.

    In the last three years, a large number of fly ash collection-efficiency experiments have been conducted, first on a bench-size SEP with about 100 6-by-6-inche screens, at room temperature, high temperature (300-350 0F), and a few tests at 1500 0F.

    Most recently, the SEP has been demonstrated in a laboratory pilot-scale setting with 6-by-2- foot screens, at room temperature. All the results confirm that this technology deserves further studies. Its high efficiency is primarily attributed to good charging of particles, to particulate agglomeration, and to the beneficial combination of different charging and particulate-capturing mechanisms, all in the laminar flow conditions.

    Utilization of this technology could result in drastic reduction of the precipitator size and cost.

• 12B2 Multi-Stage Collector (MSC™) Proof-of-Concept Pilot Design and Evaluation
  • The new MSC™ technology provides an optimum combination of single- and two-stage electrostatic precipitation augmented by barrier filtration. This arrangement ensures that essentially all dust is retained within the collector.

    The operation of the MSC™ is virtually independent of the collected material’s electrical resistivity. Hence, its application will be especially beneficial when the electrical resistivity of the collected material either exceeds 1011 or is less than 104 Ohm-cm levels.

    This paper will present details of the Proof-of-Concept (POC) MSC™ pilot unit design. The initial pilot results have shown collection efficiencies of 99.99% at face velocities (FV) of about 8 ft/min. Up-to-date results of the MSC™ POC pilot evaluation and future development work will be discussed.

• 12B3 The Development and Application of Mechanical and Electronic Multiplex Double Fields ESP
  • This paper demonstrates the technical and structure characteristics of the new type Multiplex Double Fields ESP of our company. This ESP not only separates the charging and dust collecting completely, but also optimizes the electric operation of each section and make the best of the Double Fields advantage so that it can enhance the collecting of the high resistance and low resistance dust, which improves the dust cleaning efficiency. LongKing has gained national patent on this technique.