Analysis of Some Solutions that Improve Performances of Plate-Type Electrostatic Precipitators

Transcription

1 Analysis of Some Solutions that Improve Performances of Plate-Type Electrostatic Precipitators GABRIEL NICOLAE POPA IOAN ŞORA VICTOR VAIDA 3 IOSIF POPA SORIN DEACONU Department of Electrical Engineering an Inustrial Informatics Department of Electrical Engineering Politechnica University Timişoara Str. Revoluţiei, no.5, Huneoara 3 Thermal Power Plant, Mintia-Deva ROMANIA gabriel.popa@fih.upt.ro Abstract: - The plate-type electrostatic precipitators are use in burning inustry applications an can treat large gas flows. The paper presents the maximum ionization istance, analytic an graphic, near ischarge wires epening on the voltage supply frequency an the ischarge wires raius. A problem of this type of precipitator is ifficulty to collection high resistivity fly ash. In the inlet section the fly ash resistivity is moerate an is necessary to charge ust particles as many is possible. It is useful to use traitional c energization. For the mile section an especially for outlet section, where the fly ash resistivity is high, it is necessary another supply solution for section because the charging particle ecrease when is use traitional c energization. The paper presents analysis of ifferent types supplies of ESP sections. The intermitent energization of sections can be a cheap solution to mile an outlet section (without change the power supply structure, it is necessary the change of the automatic voltage control unit). It is important to know the current-voltage characteristics to obtain the optimal control of the amplitue, the voltage shape, the input power an the collection efficiency. With comparative analyze of the measure an compute characteristics, with ifferent mathematical moel of current-voltage characteristics, it can be foun which moels estimate the current-voltage characteristics for plate-type electrostatic precipitators. Key-Wors: plate-type electrostatic precipitators, c energization, intermitent energization, current-voltage characteristics, mathematical moels Introuction In the most burning applications its use the plate-type electrostatic precipitators (ESP) because have following avantages: can be size for large gas flow, can operate in a wie range of temperatures an the collection efficiency is high. In ESP, the gas particles from the burning process, are passe through electric fiel where it is generating electrical charges (through Corona effect) attaching to gas particles. The ischarge wires are connecte to negative (-) polarity of power supply, an electric charge of gas particles is negative. Thus, the gas particles are eflecte by the electric fiel from the ischarge wires to collecting plates that are connecte to earth. The gas particles are remove to collecting plates into receiving hoppers by mechanical shocks. The ESPs are mae from a number by 3 4 of series sections, each of them is energize by its own transformer rectifier set an has its own hoppers [,]. Corona is the ionization of gas molecules by high energy electrons in the region of a strong electric fiel [,3,4]. The electrical current is forme by gas ions from space between electroes. The velocity of the gas ions is proportional with electrical fiel applie an the constant calle electrical mobility of gas ions []. The onset corona ischarge occurs over a wie range of voltage. For traitional c energize ESP sections (most use metho), the corona currents are relatively small (ma) for high applie voltage (tens of kv). The current increase nearly proportional with applie voltage until breakown occurs [4,5]. The electric fiel strength between the electroes (the ischarge wires an the collecting plates) epens on two factors: the surface charges on the electroes (ue the applie voltage) an the space charge component (ue the ions from electroe spacing) [,6]. A number of numerical methos have been propose to solve problems for complex ischarge wire electroe geometries using finite ifference, ISSN: Issue 8, Volume 7, August 8

2 finite elements or charge simulations software [6,7,8]. It has been evelope finite ifference metho to compute the steay state corona current istribution in the ESP sections to compute maximum corona current which can be carrie in ifferent geometric configuration of electroes section [7]. Traitional c energization of ESP sections are characterise by low current corona an the ionization processes is very small near the ischarge wires [,5,9]. The efficiency of ESP may be improves by electrical or mechanical means. Because a mechanical upgrae of ESP sections is too expensive, a solution to improve collection efficiency is to moify electrical equipment an/or control unit. The most ESPs are supply by single phase thyristors high voltage power supplies that represent consierably lower investments cost for ESP supplies [,]. The collection of ust particles in ESP sections is etermine by migration velocity w (particle velocity perpenicular to the collecting plates). The supply voltage an the ischarge wires geometry have an important effect on the migration velocity. Irregular ischarge wires (e.g. barbe plate, barbe wire an spike ban) are useful to corona electroes []. The main goal of the control unit is to maintain the voltage from ESP sections near Corona voltage. For this reason the voltage must be rise until occur ischarges in ESPs. After a ischarge, is come the perio of recover voltage that must be shorter after the ischarge. To create an optimal control algorithm, it is important to know the currentvoltage characteristics for ESPs [,6,3]. The energization of ESP section is limite by the following conitions [,4,5]: - sparking that limit the peak voltage an is affecte by other parameters. The electrical energy increase an the ust collection reuce an the power must be turne off to quench this arc; - back corona when the ust emission increase ue the prouction of opposite polarity ions an the energy consumption increase; - equipment capacity that epens on peak voltage an average voltage; - SO 3 conitioning through injection SO 3 into the gas (before ESP) will reuce the ust resistivity an prevent back corona; - moisten of ust will act to reuce the ust resisitivity an minimize back coron Ionization istance from ischarge wires An important problem is the etermination of spatial charge istance. Let be consier a ion which has the mobility k i an it is place in alternating fiel with frequency f, by electric fiel strength E, the fiel is mae by a ischarge wires with raius r e, that is connecte at high potential that etermine Corona ischarge [,]: v = ki E. () The ion spee may be also compute epening on the istance by ischarge wire r an the time t: r v =. () t The electric fiel strength E it is not constant an epens by ischarge wire raius r e, the istance r until place where is calculate the electric fiel strength E an by the electric fiel strength at the ischarge wire surface E e : re E = Ee. (3) r From (), () an (3) results: re r ki Ee =. (4) r t After integration (4) became: T r ki Ee re t r max =, (5) re f =. (6) T From (5) an (6) can be compute r max : ki Ee re rmax = re +. (7) f To compute the maximum ionization istance r max let be consier the following example from inustry [,5]: k i = [cm /(V s)], E e = 4 [kv/cm], r e (.-.) [cm], an f (.5-5) [khz]. With these ata an with MatLab 5.3 software, are mae two graphics: r max epens on ischarge wire raius r e an electric fiel frequency f, on frequency omains. In fig..a is the frequency omain 5-5 [Hz] an in fig..b is the frequency omain.5-5 [khz]. To prouce large numbers of charge carriers on surface of ischarge wires a critical fiel strength has to be overcame when fee with negative supply. Because of natural raioactivity some molecules become ionize an recombine immeiately. The electrons will be accelerate an etermine new ionizations through collision of gas molecules. If electrons i not attach by gas molecules, then electrons etermine exciting molecules that encourage an easy ionization at a future collisions. At a bigger ISSN: Issue 8, Volume 7, August 8

3 istance by ischarge wire, the electrons have not a high spee an these will be attach by ust particles that are lay own on collecting plate (that are connecte to earth). The positive ions that appear in the collision time move to ischarge wire an etermine new electron emissions. If the ischarge wire is positive, the electrons from space between electroes will be accelerate, an will be collision with gas molecules an occur positive ions that are move through collecting plate that are connecte to earth. r max [cm] 35 r max [cm] 3 5 f [Hz] f [khz] r e [cm] r e [cm] Fig.. Maximum istance ionization epening on frequency an ischarge wire raius The gap between electroes (ischarge wires an collecting plates) epens on voltage frequency when the ESP section is supply with alternating voltage. If the istance between electroes is small enough an the ions arrive to opposite polarity electroe into half perio, then the Corona ischarge is the same with negative or positive supply of ischarge wires. If the istance between electroes is bigger, the spatial charge carriers keep the polarity with the voltage ecrease. The ions guie to electroes until the ischarge wire potential change the polarity. Thus, appear an oscillation trajectory of ions [,6,9]. 3 DC an intermitent energization of ESP sections The signals use by the control unit are presente in fig.. L 38 V c. 5 Hz L Phase control thyristors primary current current transformer primary voltage Automatic voltage control unit High voltage oil tank Linear inuctor HV transformer voltage transformer current shunt + ma signal seconary current seconary voltage HV rectifier Fig.. Power supply of ESP section ivier kv signal ESP section The traitional c energization is obtaine with power supply presente in fig.. To obtain c energization can be also use high voltage boost conevertors [,6]. The line voltage is controlle by a thyristor controller, an then it is applie to the primary of high voltage transformer. The high voltage it is rectifie by high voltage rectifier brige, an the rectifie seconary voltage is applie to the ischarge wires from precipitator section. The rectifie seconary voltage is connecte (- to ischarge wires an collecting plates are earthe) to generate negative corona in the precipitator section. An inuctor is connecte in series with thyristors to increase the short-circuit impeance uring the events from ESP sections (sparking, arcing, or shortcircuit). The high voltage can be also measure with another type of ivier [7]. The firing angle of the thyristors must be controlle automatically because most of processes in ESP sections are subject to both slow an fast changes in the operating conitions. Some parameters like gas temperature an humiity, ash resistivity an fuel characteristics are change frequently [8,9]. The control units are base on microprocessors (or microcontrollers) an peripheral circuits which offer powerful performance. The control corona currents from precipitator sections are mae through using primary an seconary values (voltages an currents). Sometimes, the installation of opacitymeter in the stack is use to monitoring the ust emission an has two functions [,]: ISSN: Issue 8, Volume 7, August 8

4 - to optimizing the operation of ESP sections; - to save the energy uner easy conitions. The rms an the mean current through ESP section are: T I rms = i ( t ) t, (8) T T I mean = i ( t ) t. (9) T Another important quantity are, the peak factor k P an the form factor k F of the precipitator section: I peak k P =, () Imean Irms k F =. () Imean Ientically, can be etermine these quantities for precipitator section voltage. TR Set Limit 84. kv V peak = 6.6 kv V avg = 58.5 kv V min = 4.9 kv Peak/Average =.4 Fig.3. Voltage shape in ESP section for traitional c energization Intermitent energization is a metho to saving energy an improving the collection efficiency for high resisitivity ust. It is use the same electrical equipment employe in traitional c energization. The control unit suppres a number of even halfcycle of primary current. The egree of intermittence (D) is efine as a number of current pulses in one energization uty cycle ivee by the number of half cycles inclue the energization cycle. The current for intermitent energization (I IE ) epening on current for traitional c energization (I DC ), a parameter k (.5), an egree of intermittence D []: I DC I IE = k. () D D>3 (o, up to 5), that emonstrate low current for intermitent energization an power consumption of ESP is reuce. Through ust resisitivity measure, the energization controller automatically etects the high resisitivity ash an provies the optimum ESP performance uner ifferent ust resistivity conitions [5]. TR Set Limit 84. kv V peak = 6.7 kv V avg = 56.5 kv V min = 46.4 kv Peak/Average =.9 Fig.4. Voltage shape in ESP section for intermitent energization (D=:3) If it is note with q i [g/m 3 ] the inlet electrostatic precipitators ust concentration an with q o [g/m 3 ] the outlet electrostatic precipitators ust concentration, the ESP collection efficiency η[-] is: qi q o q o η = =, (3) qi qi S α = c, (4) Q α [m /m 3 /s] is specific collecting area, S c [m ] is electrostatic precipitator collecting plates area, an Q[m 3 /s] is the gas volume flow. The Deutsch equation for electrostatic precipitator collection efficiency is [,,]: w α η = e, (5) w[m/s] is migration velocity of ust particles towars collecting plates. 4 Analysis of ifferent types supplies for ESP sections The power consumption of inustrial ESP are be in the range of hunre of kw [9]. At the inlet section (first section), the istribution of particles is very inhomogeneous an the concentration is very high. The ust resistivity is low to moerate (< [Ω cm]) an is necessary to charge particles as many is possible through high corona currents. The back corona rarely occurs in the inlet section. In the mile section the istribution of particles becomes homogeneous an the concentration of ust ISSN: Issue 8, Volume 7, August 8

5 particles is lower. The ust resisitivity increase an the back corona occurs more frequent an it is necessary other time of energization (intermitent or pulse energization). The average iameter of ust particles is less than in the first section. In the outlet section (last section) the concentration of ust particles is low, but the ust particles is smaller an the ust resisitivity is high (> [Ω cm]). Back corona often happens in the outlet section. For high resisitivity is necessary intermitent or pulse energization. The ESPVI 4..a software is an ESP performance preiction moel, is sponsore by the Unite States Environmental Agency. This software has a lot of parameters of ESP []: the general electrostatic precipitator parameters; the electrical parameters for every section; c. the gas parameters;. the ust parameters. It is mentione that this software automatic executes aapting of parameters for respect of the connection among parameters. For each parameter are physic limitations. Table The general parameters of the ust an the gas Resistivity [Ω cm] Gas flow [m 3 /s] Velocity of gas [m/s] Temperature [ C] Pressure [atm] Section The inlet ust concentration [mg/m 3 ] Dynamic viscousity [kg/(m/s)] Table The electrical parameters of the plate-type electrostatic precipitators Voltage [kv] Current ensity [na/cm ] Peak voltages [kv] Section Peak Type of energization currents [A].8 traitional c energization.8 traitional c energization 3.8 traitional c energization 4.8 traitional c energization The simulations are mae for ESPs from a thermal power plant, that have the maximum gas flow Q=65 [m 3 /h], the apparent power S=66 [kva]. The ESPs have four ientical sections. The main constructive ata for one section are: plate area S platearea = [m ]; the istance between the collecting plates an the ischarge wires s =.75 [m]; length L = 4.3 [m]; height h = [m]; with l = 6. [m] [,,3]. The ischarge wires are isposing in ucts an are equiistances. First ischarge wire is place at 9 [cm] from the uct inlet, an the istance among the ischarge wires is by 4 [cm]. [%] Particles iameter [μm] Fig.5. Gas particles masses istributions epening on gas particles average iameter From fig.5 it is observe that in volume unity of resiual gas, the gas particles with iameter between [μm] an 6 [μm] have bigger masses. Although the gas particles masses with iameter uner [μm] have less value that the other particles masses, its number is bigger. The ESP collect more ifficult the particles with iameter uner [μm] [8]. The collection efficiencies of ESP from a thermal power plant were measure [] an simulate for ten technological situations, for two ESP note with ESPA an ESPB, are ifferent each other through inlet ust concentrations, that are note in table 4 from I to V. The relative errors of collection efficiency are very small that emonstrate the performance of the ESPVI 4..a software on conitions that are using the real technological (from inustry) an electrical parameters. The migration velocity an collection efficiency are small for ust particles with mean iameters uner 5[μm], an are big for ust particles with mean iameters over [μm]. Thus, at traitional energization, the collecting of ust particles with iameter very small (uner 5[μm]) is lower. ISSN: Issue 8, Volume 7, August 8

6 Migration velocity [cm/s] Particles iameter [μm] other geometrical imensions are the same (it was moify only the number of ischarge wires from sections). Table 3 The types of energizations use in measurements an simulations of electrostatic precipitators sections Section Case a Case b traitional c energization traitional c energization traitional c energization traitional c energization 3 traitional c energization intermitent :3 4 traitional c energization intermitent : Collection efficiency[%] Particles iameter [μm] Fig.6. Migration velocity (a) an collection efficiency (b) epening on particles average iameter for traitional c energization for all ESP section It was simulate the collection efficiency (fig.6) for ESP epening on ischarge wires, when the Fig.7. Collection efficiency epening on ischarge wires in the uct It was simulate the collection efficiency (fig.7) for ESP epening on istance between the collecting plates an the ischarge wires, when the other geometrical imensions are the same (it was moify only the istance between the ischarge wires an collecting plates). Table 4 The collection efficiency for the types of energizations presente in table 3 Inlet ust Outlet ust Collection efficiency Relative error Cases concentration concentration Simulate η s [%] η q i [g/m 3 ] q o [g/m 3 s ηm [%] ] η m [%] (6) Case a Case b ηm (table 3) (table 3) ESP A case I ESP B case II ESP A case III ESP B case IV ESP A case V ESP B case VI ESP A case VII ESP B case VIII ESP A case IX ESP B case X Collection efficiency[%] Number of the ischarge wires ISSN: Issue 8, Volume 7, August 8

7 Collection efficiency[%] Distance between the electroes s Fig.8. Collection efficiency epening on istance between electroes (ischarge wires an collecting plates) Increasing the istance between electroes resulte in ecrease collection are Through increasing sectionalization, the inlet section is use for low resisitivity fly ash an the mile an the outlet section are use for high resisitivity fly ash. It is possible to aition a precharge fiel provies significant improvments in collection (especially for submicron ust particles) [8]. Wie plate spacing between electroes, without an increase in overall ESP size an voltage supplies, will not increase the collection efficiency. When high resisitivity fly ash is processe a wie plate spacing is necessary (usually,. [m]). The back corona is limite by increasing electroe spacing []. Then, it was simulate the collection efficiency (fig.8) for ESP epening on types of sections energizations for ESP with four sections. In fig.8 was note wih DC energize of sections with continuous voltage (ieal); : energize with traitional c energization; : energize with monowave rectifing voltage (with only one ioe); :3 intermitent energization with orer 3 (D=3), so on. Collection efficiency[%] DC Supply type Fig.9. Collection efficiency epening on types of sections energizations The growing up of ischarge wires number from electrostatic precipitator sections ucts has a positive effect on electrostatic precipitator performances, however involves a supplementary price. A bigger value of istance between the ischarge wires an collecting plate causes increase of collecting efficiency, but involves more performance electrical isolations an power supplies with bigger voltages. Increasing of intermitence of electrostatic precipitator sections power supplies causes increasing of collection efficiency (especially for high resistivity fly ash). 5 Mathematical moels for currentvoltage characteristics The current-voltage characteristics are very important to estimate the collection efficiency, the control an the sections power of the ESPs. The analytic current-voltage characteristics mae with electric fiel strength E, particle charge ensity ρ s, current ensity j, ion mobility k i, with ifferential equations [4,6,7]: ρ E = s, (6) ε j =, (7) E = V, (8) j = ρs ki E. (9) The mathematical moels have, in general, the following equation for current-voltage characteristics [3]: I = ki G U ( U U ), () I[A/m] is the specific current, U [V] is the voltage between the electroes, U [V] is the initial Corona voltage an G[s/(m 3 Ω)] is a coefficient that epens by use metho. Metho (Deutsch - the istance [m] between the ischarge wires will be neglect) 8 π ε G =, () 4 s 4 s ln π π re s[m] is the istance between the ischarge wire an the collecting plate, r e [m] is the equivalent raius for the ischarge wire. (Deutsch - the istance [m] between the ischarge wires is not be neglect) 3 ε r G = π A + B. () ISSN: Issue 8, Volume 7, August 8

8 .7 If.8 s/.3 then A =. 7 ; B =. 75, s.585 an if.5 s/<.8 then A = ; B = s Metho 3 (Cooperman) 4 π ε G =, (3) s Z ln r π s e Z = e π. (4) In a ESP, each section supplies separate: Itot = ltot ki G U ( U U ), (5) I tot is total current through ESP section, l tot is the total length of the ischarge wire from a ESP section. The initial Corona voltage for a section of ESP may be compute with [,6]: m U = E re ln, (6) re E is a initial electric fiel strength (7). If s/<.3 4 then m = s, if.3 s/< then π s.96 m =.8 e, if s/ then m = π e π. Peek propose a semiempirical relation to fin the initial electric fiel strength E [,3]: δ E = A δ + B, (7) re p T δ =, (8) p T δ[-] is the relative ensity of gas, A[V/m] is a constant that epens of gas an B[V/m.5 ] is a constant that epens the Corona polarity, p = 5 [N/m ] is the pressure at temperature T =73 [K], an p [N/m ] is the pressure at temperature T. For the ESP, when it is negative Corona, the constants have the value: A=3. 6 [V/m] an B=9 4 [V/m.5 ]. s At power plant, a generating set (with maximum MW) has two ESPs (note with A an B). Were measurate the currents an the voltages, for each sections of an ESP, for a minimum loa (electrical power of generating set 45-5 MW, t gas = 4.5 C) an for a maximum loa (electrical power of generating set 75-9 MW, t gas = 5 C) [,4,5]. The measure an compute current-voltage characteristics are present in fig.-7 for a minimum an maximum loa, for every section Metho Fig.. Current-voltage characteristics for ESP A at minimum (a) an maximum (b) loa: section Metho 6 Comparative analyze of the measurement an compute characteristics For an ESP with four section from a thermal power plant where mae graphics currents epening on voltages measurate [] an compute with three methos (methos,,3) using equations ()-(5). Each of the ESP section has the following characteristics: s=.75[m], =.4[m] (s/=.5), r e =.75[mm], l tot =88[m]. ISSN: Issue 8, Volume 7, August 8

9 Metho Fig.. Current-voltage characteristics for ESP A at minimum (a) an maximum (b) loa: section U [ kv] Fig.. Current-voltage characteristics for ESP A at minimum (a) an maximum (b) loa: section 3 Metho Metho Metho Fig. 3. Current-voltage characteristics for ESP A at minimum (a) an maximum (b) loa: section Fig. 4. Current-voltage characteristics for ESP B at minimum (a) an maximum (b) loa: section Metho Metho Metho J [μa/m ] Metho ISSN: Issue 8, Volume 7, August 8

10 Fig. 5. Current-voltage characteristics for ESP B at minimum (a) an maximum (b) loa: section Fig. 6. Current-voltage characteristics for ESP B at minimum (a) an maximum (b) loa: section 3 m ] μa/ J [ Metho Metho Metho J [ μ A/m ] Metho Fig. 7. Current-voltage characteristics for ESP B at minimum (a) an maximum (b) loa: section 4 After the stuy of current-voltage characteristics from fig.-7 for minimum an maximum loa, the best compute current-voltage characteristics are for sections an 3. It can not be specify that methos ( or or 3) are better. For minimum an maximum loa, for a specify metho, the results of compute characteristics are close. The on set Corona voltages have big values at the input sections an have smaller values at the output sections of ESP. At the same time with gas cleaning, the onset Corona voltage in a clean gas (towars output sections) has small values. The ischarge voltages in the ESP sections are bigger in the input sections comparative with output sections. For the same sections, the breakown voltages, in general increase with ust concentration (at section an ). The smaller values of breakown voltages from sections (3 an 4) are present because fault control of voltages from section or unproper alignment of ischarge wires Metho Metho ISSN: Issue 8, Volume 7, August 8

11 7 Conclusion It was etermine the maximum istance until the ions are move, with (7). If alternating fiel frequency ecrease, the maximum istance increase (fig.). The ESP supply is not efficient only with alternative voltage because occurs an oscillation trajectory of electric charge ust particles. If overtakes a limit of voltage frequency, the oscillation amplitue of charge ust particles is lower than the istance between electroes. Were analysis ten cases for inustrial ESP operating in a thermal power station, the relative errors of collection efficiency, compare with real measurements, are very small (table 4). These errors show the moel performances use by ESPVI 4..a software. The migration velocity an the collection efficiency (fig.6) have small values for particles with iameter uner 5 [μm] an have big values for particles with iameter over [μm], when the supplies of ESPs sections were mae with traitional energization. To improve the collecting performances of ESP, from the analysis solutions (table 4), a useful metho is to use special evices to achives an intermitent power supplies (intermitent energization) for mile an outlet section where is high resistivity fly ash. With this metho the collection efficiency increase an the electric energy consumption ecrease. This solution is vali when is collecting ust with high resistivity (> [Ω cm]). The growing up of ischarge wires number from the sections ucts (fig.7) etermines a little increase of collection efficiency, but the cost, mount an maintenance prices increase. The increasing of istance between the ischarge wires an the collecting plates (fig.8), causes a light increasing of collection efficiency, but must upgrae ESP sections, replace the electrical isolations an power supplies (to obtain a higher voltage). Through ifferent types of ESP power supplies sections can consierably improve the collection efficiency of ESPs. Depening on the ust an gas properties for each ESP section, by choosing the right combination of power supplies an process control the ESP efficiency can be improve. For an ESP from inustry (a thermal power plant) for a minimum an a maximum loa (for two power of no. generating set) was mae comparision between measure an compute (with ()-(5)) current-voltage characteristics. The best moelling of current-voltage characteristics are for sections,3 (mile section) for ESP A an ESP B. For sections,4 (inlet an outlet section) the mathematical moeling of characteristics is unsatisfactory because the ESP works in inustrial conitions (unproper alignment of ischarge wires, the absence of some ischarge wires from sections, some semisections are not supplies, fault control of Corona power at ischarge wires) an some parameters use in moels were approximate (E, U, k i, r e ). It is important to preict the current-voltage characteristics for ESP sections because can be use to control corona power, to optimization the spark rate, to optimization the rapping sequences an to control the energy management system. To compute realistic current-voltage characteristics is necessary to estimate the corona current injecte in ionization region as a function of applie amplitue an shape voltage an epening on configuration of ischarge wires. Also, it is necessary to use a comprehensive negative corona moel that involve various phenomena like: glow corona, Trichel pulses, sparking, breakown streamers, etc. References: [] K.R. Parker, Applie Electrostatic Precipitation, Chapman an Hall, Lonon, U.K., 997. [] G.N. Popa, Contributions to Improving Performances of Plate-Type Electrostatic Precipitators for Bi-Phase Systems Gases-Soli Particles, PhD Thesis, Politechnica University Timişoara, Romania, 4, (in Romanian). [3] E. Rothery, Atmospheric Emissions Control Techniques for Inustrial Applications, the st International Conference on Environmental Management an Technologies, Cairo, Egypt, 997, pp.-. [4] E. Lami, F. Mattachini, R. Sala, H. Vigl, A Mathematical Moel of Electrostatic Fiel in Wires-Plate Electrostatic Precipitators, Journal of Electrostatics, no.39, 997, pp.-. [5] E. Kuffel, W.S. Zaengl, J. Kuffel, High Voltage Engineering. Funamentals, Linacre House, Joran Hill, Oxfor, U.K.,. [6] A. Melin, Electrohyroynamic Moelling of Fine Particle Collection in Electrostatic Precipitators, PhD Thesis, School of Physics, University of New South Wales, Australia, 998. [7] E. Lami, F. Mattachini, I. Gallimberti, R. Turri, U. Tromboni, A Numerical Proceure for Computing the Voltage-Current Characteristics in Electrostatic Precipitator Configurations, Journal of Electrostatics, vol.34, pp , 995. [8] M.R. Talaie, M. Taheri, J. Fathikaljahi, A New Metho to Evaluate the Voltage-Current ISSN: Issue 8, Volume 7, August 8

12 Characteristics Applicable for a Single-Stage Electrostatic Precipitator, Journal of Electrostatics, no.53,, pp.-33. [9] H.J. Schmi, E. Schmi, Investigations in to the Local Mass Flux of Dust to be Precipitate at the Collecting Electroe, the 6 th International Conference on Electrostatic Precipitators, Buapest, Hungary, 996. [] N. Grass, Application of Different Types of High-Voltage Supplies on Inustrial Electrostatic Precipitators, IEEE Transactions on Inustry Applications, vol.4, no.6, november/ecember, 4, pp [] N.Y.A. Shammas, S. Eio, D. Chamun, Semiconuctor Devices an Their Use in Power Electronic Applications, WSEAS Transactions on Power Systems, Issue 4, Volume 3, April 8, pp [] M. Jęrusik, J.B. Gajewski, A.J. Świerczok, Effect of the Particle Diameter an Corona Electroe Geometry on the Particle Migration Velocity in Electrostatic Precipitators, Journal of Electrostatics, no.5-5,, pp [3] S.M. Digă, Contribution on Electrostatic Precipitators Improving Performances, PhD Thesis, Politechnica University Bucureşti, Romania, 998, (in Romanian). [4] R.T. Truce, W. Reibelt, New Technology Improves Electrostatic Precipitator Performance, the 7 th International Conference on Electrostatic Precipitators, Kyongju, South Koreea, 998. [5] M. Jerusik, J. Jerusik, Exploitation Experience of the Cooperation of an Electrostatic Precipitator an a Desulphrisation Installation, the 6 th International Conference on Electrostatic Precipitators, Buapest, Hungary, 996. [6] Z. Yanlei, Research an Implementation of a Novel DC High Voltage Power Supply, WSEAS Transactions on Circuits an Systems, Issue, Volume 7, February 8, pp [7] H. Tatizawa, G.F. Burani, P.F. Obase, Application of Computer Simulation for the Design of a New High Voltage Transucer, Aiming to High Voltage Measurements at Fiel, for DC Measurements an Power Quality Stuies, WSEAS Transactions on Systems, Issue 5, Volume 7, May 8, pp [8] N. Plaks, Improving Collection of Toxic Fine Particles in ESPs, the 6 th International Conference on Electrostatic Precipitators, Buapest, Hungary, 996. [9] N. Grass, Fuzzy Logic-Base Power Control System for Multi Fiel Electrostatic Precipitators, IEEE Transactions on Inustry Applications, vol.38, no.5, september/october,, pp [] B. Navarrete, L. Cañaas, V. Cortés, L. Salvaor, J. Galino, Influence of Plate Spacing an Ash resistivity on the Efficiency of Electrostatic Precipitators, Journal of Electrostatics, no.39, 997, pp [] ***, ESPVI 4.. Performance Preiction Moel, National Technical Information Service, U.S.A., 996. [] ***, Operation Optimization of ESP no. with 4 sections, Thermal Power Plant Mintia Deva, contract no.785-/998, S.C. ICPET S.A., Bucharest, Romania, 998. [3] V. Vaia, I. Şora, G.N. Popa, The Improving of Plate-Type Electrostatic Precipitators Performances, National Conference on Power Energy, Neptun, Romania, 4. [4] ***, Operation Optimization of ESP no. with 4 sections, Thermal Power Plant Mintia Deva, contract no.785-/998, S.C. ICPET S.A., Bucharest, Romania, 998. [5] I. Şora, G.N. Popa, I. Popa, The Stuy of Current-Voltage Characteristics for Plate-Type Electrostatic Precipitators, the 7th International Conference on Applie an Theoretical Electricity, Băile Herculane, Romania, 4. ISSN: Issue 8, Volume 7, August 8