Electrostatic precipitators have been used widely in industry, and play an important role in environmental protection. An electrostatic precipitator (ESP) can be operated with a high collection efficiency and a low pressure drop. Recently, an ESP also has been used for cleaning indoor air. In this review, principles of electrostatic precipitation, such as particle charging, migration velocity of charged particles and collection efficiency, are described. The performance of the ESP deteriorates by abnormal phenomena, including back corona for treating high resistivity dust, abnormal re-entrainment for low resistivity dust, and corona quenching for fine dusts. To cope with these phenomena, new technologies have been developed. Pulsed energization is a technique which copes with high resistivity dusts, and this results in lower power consumption. Using pulsed energization, non-thermal plasma can be generated and chemical reactions can be promoted for treating gaseous pollutants such as NO and volatile organic compounds. Wet ESP can also remove dusts and gaseous pollutants simultaneously. These new advancements will widen the field of application of electrostatic precipitation. Some novel applications of ESP, such as removal of dioxin from incinerators, are also included in this review.

Electrostatic precipitation

Air pollution caused by gas emission of pollutants produced from a wide range of sources including coal, oil and gas burning power plants, diesel engines, paper mills, steel and chemical production plants must be reduced drastically and urgently, as mandated by recent worldwide national legislation which recently are being reinforced increasingly by international agreements. Non-thermal plasmas in which the mean energy of the electrons is substantially higher than that of the gas offer advantages in reducing the energy required to remove the pollutants. The electrical energy supplied into the discharge is used preferentially to create energetic electrons which are then used to produce radicals by dissociation and ionization of the carrier gas in which the pollutants are present. These radicals are used to decompose the pollutants. There are two technologically promising techniques for generating non-thermal plasmas in atmospheric gas pressure containing the pollutants, namely electron beam irradiation and electrical discharge techniques. Both techniques are undergoing intensive and continuous development worldwide. This is done to reduce the energy requirement for pollutant removal, and therefore the associated cost, as well as to obtain a better understanding of the physical and chemical processes involved in reducing the pollutants. In the present paper only electrical discharge techniques are reviewed and emphasis is given to the more recent published work. The paper summarizes the chemical reactions responsible for the removal of the major polluting constituents of NO, NO/sub 2/ and SO/sub 2/ encountered in flue gases and exhaust emissions. The constructional features of the various types of electrical discharge reactors commonly employed in the removal of gas pollutants as well as pilot systems used in industrial plants are described briefly The results on the removal efficiency of the various pollutants including hydrocarbons and volatile compounds and their dependency on the type of discharge reactor, the type and the magnitude of the applied voltage (dc, ac and pulsed), the polarity of the voltage (de and pulsed), the effect of the pulse width, the initial concentration of the pollutants, the addition of ammonia, argon and other hydrocarbons, the gas flow rate, the residence time of the pollutants in the discharge reactor, the gas temperature and on the type of the gas constituents will be reviewed. The removal of pollutants using arc plasmas will be discussed. The specific energy density which is supplied in various forms of electrical discharges to reduce the pollutants is discussed. The energy required to remove the pollutants is expected to be one of the main considerations in selecting the technology to be used to remove the pollutants and therefore it is of prime importance.

Air pollution control by electrical discharges

Pulsed power has been used to remove nitric oxide (NO) in a mixture of nitrogen, oxygen, and water vapor simulating the flue gases from a power station stack. The effect of the pulsewidth at a fixed applied voltage on NO removal concentration was studied. The dependence of the energy efficiency of the removal of NO at a fixed applied voltage on the pulsewidth, on the removal ratio of NO and on the discharge current was investigated. This removal energy efficiency increases with decreasing pulsewidth and decreasing removal ratio of NO.

Improvement of NO/sub X/ removal efficiency using short-width pulsed power

Non-thermal plasma (NTP) has been introduced over the past several years as a promising method for nitrogen oxide (NOx) removal. The intent, when using NTP, is to selectively transfer input electrical energy to the electrons, and to not expend this in heating the entire gas stream, which generates free radicals through collisions, and promotes the desired chemical changes in the exhaust gases. The generated active species react with the pollutant molecules and decompose them. This paper reviews and summarizes relevant literature regarding various aspects of the application of NTP technology on NOx removal from exhaust gases. A comprehensive description of available scientific literature on NOx removal using NTP technology is presented, including various types of NTP, e.g. dielectric barrier discharge, corona discharge and electron beam. Furthermore, the combination of NTP with catalyst and adsorbent for better NOx removal efficiency is presented in detail. The removal of NOx from both simulated gases and real diesel engines is also considered in this review paper. As NTP is a new technique and is not yet commercialized, there is a need for more studies to be performed in this field.

/pdf/the-role-of-non-thermal-plasma-technique-in-nox-treatment-a-4qq33uln0h.pdf

The role of non-thermal plasma technique in NOx treatment: A review

Pulsed power accelerators compress electrical energy in space and time to provide versatile experimental platforms for high energy density and inertial confinement fusion science. The 80-TW “Z” pulsed power facility at Sandia National Laboratories is the largest pulsed power device in the world today. Z discharges up to 22 MJ of energy stored in its capacitor banks into a current pulse that rises in 100 ns and peaks at a current as high as 30 MA in low-inductance cylindrical targets. Considerable progress has been made over the past 15 years in the use of pulsed power as a precision scientific tool. This paper reviews developments at Sandia in inertial confinement fusion, dynamic materials science, x-ray radiation science, and pulsed power engineering, with an emphasis on progress since a previous review of research on Z in Physics of Plasmas in 2005.

/pdf/review-of-pulsed-power-driven-high-energy-density-physics-35pt9lyqe1.pdf

Review of pulsed power-driven high energy density physics research on Z at Sandia

Dry scrubbing of flue gas to reduce emission of acid rain orming gaseous NO, and SO2 has been studied at moderate scales t various laboratories using pulsed corona and electron beam (eeam) irradiation. For these technologies to become economically iable inlarge coal-fired power plants, very high process efficiencies nd system reliability must be demonstrated. In this paper, we :view the two processes, pulsed corona and e-beam irradiation, dative to theirpulsepowerrequirements. Approaches forprocess nprovement through application of pulse power techniques will e presented.

Flue gas irradiation using pulsed corona and pulsed electron beam technology

The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators To increase the lifetime of these insulators, they have developed a coating called Dendresist This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators They describe its development, and compare its electrical and mechanical strength to that of other candidate coatings and materials used for vacuum insulators They discuss the mechanism for discharges through the bulk of the insulator ("worm-holes"), and how to eliminate these failures using thicker insulating rings

Vacuum insulator coating development

P. Sincemy, S. Ashby, K. Childers, C. Deeney, D. Drury, J. Goyer, D. Kortbawi, I. Roth, C. Stallings Physics International Company 2700 Merced Street San Leandro, CA 94577 L. Schlitt Leland Schlitt Consulting Services 2725 Briarwood Drive Livermore, CA 94550 DECADE is a very high peak power generator designed to drive both large area bremsstrahlung diode arrays and imploding plasma loads. For a one square meter array of bremsstrahlung diodes, the machine will deliver up to 2.5 MJ of electrical energy at a peak voltage of 1.8 MV. DECADE will drive up to 25 MA into a plasma radiation source load. The DECADE generator consists of sixteen independent pulsed power modules. Each module consists of a 500 kJ Marx that pulse charges a water transfer capacitor. The transfer capacitor discharges into a water output line through an array of triggered gas switches. The water output line then pulse charges the final inductive storelopening switch pulse compression stage. When the opening switch opens, the inductive store discharges into either an independent diode load or into a vacuum convolute that connects all sixteen modules to single imploding plasma load. Extensive testing has been completed on a half energy prototype module. The first of sixteen full power modules has been constructed and initial testing is in progress. The full DECADE facility will begin testing in mid 1995. *Work supported by the Defense Nuclear Agency DECADE Specifications DECADE is designed to produce x-rays from both bremsstrahlung and plasma radiation sources. The bremsstrahlung radiation will be produced in both a large-area and a high-dose configuration. In the large-area configuration, the average dose will be 20 kRad (in silicon), delivered over an area of 1 square meter. The maximum endpoint voltage for this case will be 1.5 MV, and the radiation pulse-width (FWMH) will be 40 ns. The high-dose configuration will deliver 80 kRad into 1500 cm2. For this case, the end-point voltage is 1.8 MV; the radiation pulse width is also 40 ns. The dose will be reproducible, so that 9 of 10 shots are within 10% of the average. The plasma radiation will be produced from aluminum wire arrays and argon gas puffs. For aluminum k-line x-rays (1.6 keV), the total yield will be 400 kJ. The argon k-line x-rays at 3.2 keV will have a total yield of 200 kJ. In both cases, the radiation pulse width will be less than 30 ns. To produce the bremstrahlung radiation, DECADE will deliver 2.5 MJ to the load in 140 ns, with a peak voltage of 1.8 MV, a diode current of 22 MA, and a diode power of 35 TW. This corresponds to performance on a single module of 160 kJ coupled into a bremsstrahlung diode. The plasma radiation will require a peak current into a short circuit of 25 MA. DECADE will operate at a rate of 3 shots per day, 12 shots per week, and will be available for users 60% of the year. It will be command fired to within f 30 ns, with a delay time between 10 ps and 10 minutes.

https://ieeexplore.ieee.org/iel2/3859/11276/00514063.pdf

The decade high power generator

DECADE is a very high pulsed power generator that will be built at Arnold Engineering Development Center in Tullahoma, Tennessee, USA, by the Defense Nuclear Agency. The full facility consists of 16 modules. A full power module (DM1) has been built and tested to verify the DECADE design at Physics International. The module consists of a 570 kJ Marx generator that pulse charges a water transfer capacitor. The transfer capacitor discharges into a water output line through an array of 6 parallel-triggered gas switches. The water output line then pulse charges the inductive store/opening switch pulse compression stage. When the opening switch opens, the inductive store discharges into an electron beam bremsstrahlung diode load. The initial testing of the DM1 module has been completed. The electrical design of the module is presented, including circuit modeling results. The test data from the module are compared to the modeling results. The concept for combining 16 modules that are similar to DM1 into the DECADE generator are presented. Test data from DM1, such as the modular timing jitter, that supports the DECADE system design are also presented.

Performance of DECADE module 1 (DM1) and the status of the DECADE machine

The development of plasma loads with implosion times approaching 250 ns allows consideration of simpler pulsed power circuits. This paper reviews various Marx generator based technologies for driving imploding plasma loads at very high current (I>20 MA) and presents conceptual sketches of three concepts. The concepts presented require development of a low inductance Marx generator which would use adaptations of existing component technology to achieve high speed. These Marx driven circuits will deliver 3 MJ of kinetic energy to the imploding plasma load.

https://ieeexplore.ieee.org/iel5/6660/17797/00825515.pdf

L. Schlitt

Papers

Flue gas irradiation using pulsed corona and pulsed electron beam technology

Vacuum insulator coating development

The decade high power generator

Performance of DECADE module 1 (DM1) and the status of the DECADE machine

Concepts for an affordable high current imploding plasma generator