Abstract: A system for separating a gaseous constituent from a gaseous mixture includes an ionization chamber, suction plenums separated from the chamber by an anode or a cathode, suction pumps for drawing gas from the plenums, and a throttle valve for controlling the entry of gas into the ionization chamber so as to maintain the chamber at a pressure less than atmospheric. The ionization chamber is bounded by an anode and a cathode, which are separated by a volume for containing the gaseous mixture. When the electrodes are oppositely charged, ions of a gaseous constituent are drawn towards the electrode of opposite polarity to the ions, and away from the other electrode. As ions approach the electrodes, they are collected and sucked though exhaust ports by the pumps.

Abstract: A device for cleaning a gas, which combines together in a single unit an Inertial Separator and an Electrostatic Precipitator, so as to reduce or eliminate the shortcomings of the latter two types of devices when they are used separately, and to synergistically enhance the efficiency and effectiveness compared to when they are operated separately in series.

Abstract: A filtration media is formed from at least one structured polymeric layer, wherein a structured surface is defined within the layer. Layers may be configured as a stack that has the structured surfaces defining a plurality of ordered inlets open through a face of the stack and corresponding ordered fluid pathways, thereby forming an ordered, porous volume. The ordered fluid pathways may be defined by a plurality of flow channels formed within the structured surfaces of the structured layers, or may be defined by a plurality of protuberances formed in an ordered pattern within the structured surfaces of the structured layers.

Abstract: A multi-stage particulate matter collector of the type used to collect particles from waste industrial gas. The collector can contain multiple narrow and wide zones formed by a plurality of parallel corrugated plates. Contained in the narrow zones are elongated electrodes with sharp leading and/or trailing edges. These electrodes provide a non-uniform electric field near their sharp edges leading to corona discharge. The corona discharge causes particulate matter in the gas flow to become charged. The region in narrow zones away from the sharp edges of the electrodes resembles a parallel plate capacitor with relatively uniform electric field. In this region, particles can be collected on the plates and on the electrode. Wide regions can contain barrier filters (bag filters) with conductive surfaces. The electric field is also relatively uniform in this region causing electrostatic collection on the plates and filter surface.

Abstract: The present invention relates to a pleated filter made of a multi-layer filter medium, including at least one filter paper layer having area weights of 30-100 g/m2, a microfiber nonwoven fabric layer having area weights 5-120 g/m2 and a support nonwoven fabric layer made of synthetic, polymeric fibers having area weights of 10-120 g/m2. The layers of the pleated filter contain fused polymer areas by which the fabric layers are bonded to the paper layer, and by which the fabric layers are made firmer within themselves. When subject to a fractional efficiency test at an initial pressure difference of at most 180 Pa, at a boundary speed of approximately 2.62 m/s and a flow speed through the filter medium of approximately 0.13 m/s, the pleated filter is able to separate at least 90% of particles greater than 0.3 &mgr;m, at least 92% of particles greater than 0.

Abstract: This invention relates to an apparatus and method to electrostatically charge or neutralize particles conveyed in a pneumatic stream. More particularly the invention is drawn to an apparatus that has at least two longitudinal chambers separated from each other with a plate electrode. Within each chamber is at least one corona charging electrode with multiple discharge points and at least one power level zone. The apparatus divides a single gas stream into a multiple streams where corona discharge polarizes or neutralizes particles with a similar or dissimilar polarity causing coalescing or separation of the particles as they exit the charging chambers.

Abstract: An electrofiltration process is provided having at least one electrostatically charged polymeric film layer having surface structures. The film layers may be configured as a collection cell that has the structured film layer defining a plurality of ordered inlet openings through a face of the collection cell and corresponding air pathways, thereby forming an open, porous volume. The air pathways are defined by a plurality of flow channels formed by the structured film layers. The electrofiltration process is coupled with an ionizer which actively induces charges onto the particles to be removed by the collection cell.

Abstract: An economical air purification system and process that greatly reduces concentrations of dust and noxious gases to provide for a cleaner and healthier enviroment for people, plants, poultry and other animals. Desirably, the special air purification system and process has a set of modules arranged for emitting overlapping flow patterns of ions. The modules can include parallel arrays of ionizers which are preferably arranged in a matrix or grid pattern. For even better results, the ionizers can comprise self-cleaning ionizers. One or more fans can be spaced from the modules to circulate the ions and air as well as draw influent air through the intake ports and exhaust purified air through the outlet ports. Heaters can also be provided to heat the circulating air.

Abstract: A device for the treatment of a flowing gas, such as an exhaust gas, includes at least one pair of smooth electrodes that are arranged opposite each other so that they form between them a discharge space through which a gas flows. For each pair of electrodes, at least one electrode is coated with a dielectric material on a side facing the discharge space. At least one electrode has one or more thickened areas facing the discharge space. The one or more thickened area has at least one opening through which the gas can flow. A device may be used in the cleaning of exhaust gases from internal combustion engines of motor vehicles as well as the cleaning of waste gases of power plants or waste incinerating plants.

Abstract: An electrofiltration apparatus is provided having at least one electrostatically charged polymeric film layer having surface structures. The film layers may be configured as a collection cell that has the structured film layer defining a plurality of ordered inlet openings through a face of the collection cell and corresponding air pathways, thereby forming an open, porous volume. The air pathways are defined by a plurality of flow channels formed by the structured film layers. The electrofiltration apparatus is coupled with an ionizer which actively induces charges onto the particles to be removed by the collection cell.

Abstract: A method of separating a low density fly ash fraction from an overall group of fly ash entrained in a gas stream including the steps of passing the gas through a duct having a first area; passing the gas stream from the duct through an expansion nozzle; passing the gas stream through the expansion nozzle and into a hollow body having a second area, whereby the second area is larger than the first area; decelerating the gas stream as it enters the expansion nozzle to separate out low density ash particles; and collecting the low density ash particles from a hopper positioned adjacent the expansion nozzle.

Abstract: An electret is described that includes a surface modified polymeric article having surface fluorination produced by fluorinating the polymeric article.

Abstract: A method for protecting an exposed surface in an enclosed space, such as a building, medical room, manufacturing space or consultation room, from harmful airborne agents. Airborne agents are charged by exposure to an electrostatically-charged cloud and an electrostatically-charged field is created for electrostatically manipulating the harmful airborne agent away from or toward the exposed surface for protecting the exposed surface from the harmful airborne agent. The harmful airborne agent may be collected on a charged surface, and destroyed by ultraviolet light.

Abstract: A method is provided for reducing the number of particles within a chamber of a fabrication tool located within a gray area of a clean room. A portable clean room station is provided that is capable of producing a white environment having fewer particles than the gray environment. The portable clean room station is positioned so that the chamber is exposed to the white environment of the portable clean room station rather than to the gray environment when the chamber is opened within the gray area. The white environment, which has fewer particles than the gray environment, is produced by employing the portable clean room station, and the chamber is then opened. Thereafter maintenance is performed on the opened chamber. Preferably the white environment is selected so as to have at least two orders of magnitude fewer particles per cubic foot than the gray environment.

Abstract: A dual- or multi-layer filter medium for air filtration, having at least one meltblown layer (2, 2a and 5) at least one meltblown layer (2 and 2a) is placed on the inlet side of the filter medium. The meltblown layer has a pore size larger than that of the next following layer or layers.

Abstract: An electrostatic air cleaner for installation in an air-circulating system, including a flow sensor for sensing the flow of air across the electrostatic air cleaner, and a switch, responsive to the flow sensor, for operating the electrostatic air cleaner only when the flow of air exceeds a predetermined threshold. More particularly, the electrostatic air cleaner includes an electrostatic air cleaner cover unit adapted to be secured over the opening in a frame in the air circulating system which frame contains at least one removable electrostatic air cleaning cell. The cover unit has a baffle for substantially blocking the air flow between the electrostatic air cleaning cell and the cover unit. The baffle has an opening therein, and a bypass tube is aligned with the opening in the baffle. An air flow sensor is disposed in the tube for sensing the air flow through the tube. The air flow sensor preferably includes a self-heating thermistor for sensing the flow in the bypass tube.

Abstract: A method and an apparatus for separating solid or drop-like particles from an air flow is provided. The air flows through a separator chamber between an electrode, ion generating means or like particle charging device disposed in the separator chamber, and a grounded collector surface, so that the particles are charged by the charging device and accumulate on the collector surface. The air flows along a substantially spiral path around the charging device in at least a part of the separator chamber so that due to the action of centrifugal force at least a portion of the particles pass toward the grounded collector surface at the periphery of the chamber. A small flow of purified air flows downwardly in a central part of the separator chamber so that it washes the charging device in the separator chamber.

Abstract: A fan assembly includes a tubular housing and electrodes which ionize air and cause the air to be filtered and to move through the tubular housing without use of moving parts, such as an impeller, thereby providing air filtration and ventilation without generation of vibrations and acoustic disturbances. An electric potential is applied between a longitudinally-oriented needle electrode and a planar or curved transversely-oriented net electrode disposed within the housing downstream of the needle electrode, thereby forming a longitudinally asymmetric electric field that ionizes and accelerates air molecules toward the net electrode, carrying the air molecules past the net electrode and through the air outlet. The assembly further includes a tubular duct electrode disposed within the housing on the outlet side ofthe net electrode, which collects ionized particles precipitated from the air.

Abstract: A vacuum filter bag is constructed of layers which include a high air permeability multipurpose layer positioned upstream in the direction of air flow of a second filtration layer. The second filtration layer can be a wet-laid filter paper, a dry-laid filter paper or a spunbond nonwoven. The multipurpose layer can be made of high bulk meltblown nonwoven, dry-laid or wet-laid high dust holding capacity paper spunblown modular or microdenier spunbond. The high dust capacity papers are characterized by greater thickness and higher air permeability than is normally used in traditional filter layers of vacuum cleaner bag structures. These characteristics allow the high capacity papers to filter large dirt particles and to capture within their pores large amounts of dust particles. This protects the downstream second filtration layer from shock loading and enables the composite structure to pass air at high rate at low pressure differential for much longer than conventional vacuum cleaner bags.

Abstract: A disposable vacuum cleaner filter bag is constructed of layers which include a filtration grade meltblown fleece layer having a basis weight of about 10-50 g/m2 and air permeability of about 100-1000 L/(m2×s) and a coarse filter layer in which the coarse filter layer is placed upstream of the filtration grade meltblown fleece layer. The coarse filter layer can include either wet-laid high dust capacity paper, dry-laid high dust capacity paper, high bulk meltblown nonwoven, Spunblown (Modular) nonwoven or microdenier spunbond nonwoven. Juxtaposition of the layers causes the coarse filter layer to capture large dirt particles and permits the filtration grade meltblown fleece layer to capture much of the remaining dust particles. The novel bag exhibits high air permeability and low pressure drop at high dust loading. A method of filtering gas through such a filter is also disclosed.

Abstract: Gas scrubbing apparatus and method, employing highly charged liquid droplets for removal of both particulates and pollutant gases from the gas to be cleaned, allowing scrubbing of uncharged particulates by means of monopole--dipole attractive forces between the charged liquid droplets and the electric dipoles induced in the uncharged particulates by the charged droplets; employing electrode geometry at the site of droplet production and charging, having spreading liquid sheet electrodes emitting the droplets from the edges of the liquid sheets, interspersed with electrically conductive induction electrodes, with electrostatic potential of no more than about 20 kv existing between the induction electrode array and the array of liquid sheets, and with spacing such that adequately high electric field strength can be maintained at the edges of the liquid sheets to allow adequate charging of the droplets emitted from the liquid sheets, without the occurrence of corona discharges which could deplete droplet charges

Abstract: An air conditioning apparatus with an air cleaning function. In the apparatus, an electric dust collector is provided in the air passage on the rear side of a heat exchanger. A heater for self-cleaning is combined with a dust collector electrode of the electric dust collector. A heat shield plate is combined with the heater. Air flow resistance is not increased although the dust collector electrode is plane in shape. An increase of air flow resistance caused by the use of the heat shield plate is also suppressed.

Abstract: A vacuum cleaner having a reduced velocity chamber with a high velocity air inlet, an electric motor, a rotary mechanism driven by the motor for creating a vacuum in the chamber, an outlet for exhausting air from the chamber, which air flows in a selected path from the air inlet, through the chamber and out the air exhaust outlet and a disposable porous sheet filter layer in the chamber for removing large solid particles from the air. The vacuum cleaner also has an improved filter, wherein the improved filter includes a layer of material to remove very fine air particles and a layer of material to remove odors from the air.

Abstract: A method of separating liquid drops from a gas stream includes the step of introducing the gas stream having a temperature greater than 600.degree. C. into shaped elements having very narrow channels through which the gas stream flows, wherein the shaped elements are of a material that becomes conductive at high temperatures and further includes the step of selecting the width of the narrow channels based on the gas stream velocity such that turbulence is generated along the flow path causing the liquid drops to strike the channel walls and deposit thereon. The apparatus for separating liquid drops from a gas stream includes a plurality of shaped elements having very narrow channels through which the gas stream having a temperature greater than 600.degree. C.

Abstract: Collection of particles from a gas stream and the separation of dissimilar particles from a gas stream by a field effect auxiliary gas cyclone (FEAGC) is enhanced by providing an inductive field that attracts or repels particles and an auxiliary gas system that complements the field effect by providing an additional independent internal control for particle velocity, particle concentration, and system delta p. The FEAGC has three adjustable operating variables: (1) an auxiliary high pressure air input orifice located in the cyclone input which is used to increase the product velocity while reducing the solids to gas ratio; (2) an electric field between the cone and the vortex that subjects charged particles to either an attractive or repelling field; and (3) an auxiliary air venturi located in the inlet of the vortex to control the delta p and to control the operating temperature of the vortex and insulating materials.

Abstract: An apparatus (10) to carry out a process for the in situ generation of agglomerate structures and the controlled influencing of the resulting agglomerates contains a closed flow duct (12) through which is directed an aerosol containing particles (14). For the purpose of the bipolar charging of the aerosol, at least one electrode pair (20, 22) is arranged in the flow duct (12), the electrode (20) being wired, so as to be ungrounded, to the negative pole of a current source, the strength of which is sufficient to produce a corona discharge between the electrodes (20 and 22). The electrodes (20 and 22) of each electrode pair are designed to be needle-shaped and are arranged to be insulated with respect to the flow duct walls, such that their tips (26) are disposed opposite each other.

Abstract: A two-stage electrostatic separator for separating particles from a particle laden gas stream includes a pre-charging section and spaced-apart gas-permeable grounded and discharge electrodes charged at opposite polarities and defining a separating section between them, the grounded electrode being positioned upstream from the discharge electrode. The particles in the particle laden gas stream are pre-charged to a certain charge in the pre-charging section and penetrate through the grounded electrode into the separating section, where the particles are separated from the particle laden gas stream. As a result, a clean gas stream exits from the separating section through the discharge electrode, and the particles separated from the particle laden gas stream are partially collected on the grounded electrode, and partially are removed with a bleed flow which is recirculated. The electrodes may be of linear or cylindrical shape, and linear electrodes may be arranged in a "zig-zag" order.

Abstract: A process for the scrubbing of undesirable substances from an exhaust gas stream which comprises passing the stream through a hollow cathode.

Abstract: Method and apparatus for purification of a discharge gas, wherein the discharge gas is selected from a group of noble gases, and most preferably is helium or argon. The purification of the discharge gas is achieved by attraction and removal of at least one ionized contaminant in the discharge gas, wherein the contaminant exhibits an ionization potential that is less than the excitation potential of the discharge gas. A discharge gas purification system may be constructed to include a discharge chamber, an inlet for supplying a pressurized flow of discharge gas into the discharge chamber, a discharge device for effecting a discharge in the discharge chamber to effect ionization of a contaminant in the discharge gas, and a bleed flow device located with respect to the discharge and to the discharge cathode for electrically attracting and removing a bleed flow of the discharge gas in the discharge chamber. A disproportionate amount of the ionized contaminants thus created are captured in the bleed flow.

Abstract: A triboelectrostatic separation apparatus includes a mixing chamber having opposed first and second charging ports, a separator having a separation chamber, first and second electrodes, and a variable voltage source for applying respective positive and negative voltage potentials to the electrodes. First and second particle streams are delivered through the first and second charging ports resulting in the impingement of the particle streams upon each other within the mixing chamber, thus enhancing the electrostatic charging of the particles contained within the particle streams. The apparatus may also include a pre-separator having a pre-separation chamber, a charged particle collection chamber and a plurality of feed passageways providing fluid communication between the pre-separation and the charged particle collection chambers.

Abstract: A device and method for controlling particulate air pollutants of the present invention combines filtration and electrostatic collection devices. The invention includes a chamber housing a plurality of rows of filter elements. Between each row of filter elements is a grounded plate. Between the grounded plates and the filter elements are electrode grids for creating electrostatic precipitation zones between each row of filter elements. In this way, when the filter elements are cleaned by pulsing air in a reverse direction, the dust removed from the bags will collect in the electrostatic precipitation zones rather than on adjacent filter elements.

Abstract: The present invention is an apparatus and method for combining ions with a neutral gas and flowing the mixture with a radial flow component through a magnetic field so that the weakly ionized gas is confined by the neutral gas. When the weakly ionized gas is present in sufficient density, a weakly ionized non-neutral plasma is formed that may be trapped in accordance with the present invention. Applications for a weakly ionized non-neutral plasma exploit the trap's ability to store and manipulate ionic species in the presence of neutral gas. The trap may be connected to a mass spectrometer thereby permitting species identification after a fixed period of time. Delicate and/or heavy particles such as clusters may be held and studied in a "gentle" environment. In addition, the trap can provide a relatively intense, low-energy source of a particular ion species for surface implantation or molecular chemistry. Finally, a long trap may permit spectroscopy of unprecedented accuracy to be performed on ionic species.

Abstract: An apparatus for sampling a gas stream and concentrating selected constituents found therein. The apparatus includes a collection chamber into which a gas stream is drawn and a nozzle which sprays charged droplets of a collection fluid countercurrent to the gas stream. The charged droplets, now containing the selected constituents, are propelled to the wall under the influence of an electrostatic force and collected in a collection well at the bottom of the collection chamber. The apparatus can include a cyclonic flow inducer which imparts a circumferential component to the gas stream velocity, thereby enhancing collection efficiency by increasing the residency time of the gas stream within the collection chamber.

Abstract: The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting a composition containing an adhesive with the gas stream; collecting the undesired particles and adhesive on a collection surface to form an aggregate comprising the adhesive and undesired particles on the collection surface; and removing the agglomerate from the collection zone. The composition may then be atomized and injected into the gas stream. The composition may include a liquid that vaporizes in the gas stream. After the liquid vaporizes, adhesive particles are entrained in the gas stream. The process may be applied to electrostatic precipitators and filtration systems to improve undesired particle collection efficiency.

Abstract: An apparatus for reducing electrostatic charge of particles in a waste container. In one embodiment the waste container is coated with a liquid having a viscosity sufficient to prevent tribocharging between the waste container and the waster toner particles, and to collect toner particles deposited from the cyclone separator into the waste container. Another embodiment describes the use of a flange extending into the waste container to prevent tribocharging that can cause explosions in the waste toner bottle.

Abstract: An apparatus and method for reducing the amount of unburned carbon in raw flyash, wherein raw flyash containing unburned carbon is introduced into the tribocharger, the tribocharger producing positive and negative surface charges on the respective particles of carbon and flyash, introducing the charged particles into an electrical field containing positively and negatively charged plates, the positively and negatively charged particles being collected on the negatively and positively charged plates, and selectively vibrating the plates to selectively recover the unburned carbon and flyash.

Abstract: The present invention relates to a method and an apparatus for electrostatically precipitating suspended matter from a gas flow, wherein a precipitation electrode which is flown through by the gas flow is provided in the form of a perforated plate behind an ionization source in the direction of flow. The perforated plate has openings which are tapered on their edges in the manner of cutting edges towards the opening.

Abstract: An apparatus (10) to carry out a process, in particular for the electrically induced agglomeration of gas-borne particles, contains a closed flow duct (12) through which is directed an aerosol containing particles (14). For the purpose of the bipolar charging of the aerosol, at least one electrode pair (20, 22) is arranged in the flow duct (12), the electrode (20) being wired, so as to be ungrounded, to the negative pole of a current source, the strength of which is sufficient to produce a corona discharge between the electrodes (20 and 22). The electrodes (20 and 22) of each electrode pair are designed to be needle-shaped and are arranged to be insulated with respect to the flow duct walls, such that their tips (26) are disposed opposite each other.

Abstract: A ceiling fan for cleaning air in a room wherein each blade of the ceiling fan has a cavity open to the top and bottom surfaces of each fan blade and a filter unit in each of the cavities but within the confines of the fan blade such that, when the ceiling fan is operated, the airflow created by the ceiling fan will be forced through the filter unit from the bottom surface through to the top surface, wherein the filter units can collect airborne particles.

Abstract: An attractive portable air cleaner effectively purifies air in a room or office for added comfort and a healthier environment. Instead of using expensive custom-made filters, the air cleaner uses regular toilet paper or paper towels for customer convenience and lower customer costs. A quiet blower system circulates air through the air cleaner. Ion emitters are positioned near the intake and collector plates support and charge the paper media.

Abstract: A corona discharge reactor (10) and method for chemically activating various constituents of a gas stream by use of corona discharge is provided. The corona discharge reactor (10) includes within a conduit a discharge plate (30a,b) having a plurality of through openings (33) and a plurality of projecting corona discharge electrodes (31,31',35,35'), and an electrode plate (40a,b,c) having a plurality of through openings (43) displaced from and opposing the tips (32) of the corona discharge electrodes (31,31',35,35'). A pulsed energization scheme is employed to intermittently generate a uniformly distributed corona discharge cloud (1000) between the plurality of corona discharge electrode tips (32) and the electrode plate (40a,b,c) during passage of the gas stream through the conduit.

Abstract: A humidifier for adding liquid from a mist source to a gas flow improves the evaporation of the liquid by reducing the quantity of larger water droplets from the mist introduced to the gas flow by slowing a diverted portion of the gas flow, routing the gas flow through a partitioned chamber and deflecting the gas flow from direct impact on the mist while catching splattered liquid droplets within the humidifier.

Abstract: A clog-resistant filter and method for extracting fine particulate contaminants, such as smoke, from a gaseous fluid stream, such as air, uses an induced voltage electrode to efficiently capture the contaminant particles in a filter material whose pores are many times larger than the diameter of the particles to be captured. The filter material is physically so configured to further enhance that interaction and is disposed between at least a pair of electrodes of opposite polarity.

Abstract: A personal dust sampler hangs from a ribbon (10) attached to the user's clothing and requires no pump or power source. Dust in the air is captured by a charged PVC sheet (2) exposed at (2a) but framed by a metal foil (25) and surmounted by a metal conductor plate (6) parallel to the charged PVC sheet (2). The plate (6) is supported by conductive gridwork (3) removably attached by a flange (3) to a metal base (21). The dust captured is determined in a method by weighing or by measuring the charge loss of the PVC sheet (2).

Abstract: A high efficiency air filtration method and apparatus utilizes a fibrous filter medium that is polarized by a high potential difference which exists between two electrodes. The electrodes include an insulated electrode and an uninsulated electrode. A corona precharger is positioned upstream of the electrodes and filter. The corona precharger creates charged particles that have an opposite charge (e.g., a positive of negative charge) determined with respect to a polarization dipole proximal to the insulated electrode. These particles cancel a trapped charge that tends to accumulate on the filter surfaces proximal to the insulated electrode.

Abstract: An electrostatically enhanced separator (EES) provides mechanical and electrostatic separation of particles from gas stream to yield a compact and highly efficient separation system. The EES (10) may be incorporated in a collection system as well using a conventional collection device such as a cyclone collector (32), bag filter (37) or electrostatic precipitator (38). The EES (10) includes a cylindrical-walled separation chamber (12) with an inlet passage (13), a clean flow outlet (21), and a particle outlet passage (15). The inlet passage (13) and particle outlet passage (15) are both thin elongated slits which open tangentially to the cylindrical wall of the chamber for providing a substantially flush incoming flow path dispersed lengthwise along the wall.

Abstract: A corona-assisted electrostatic filtration apparatus which includes a cathode, an anode filter element, and a means of establishing a nonalternating potential difference between the cathode and the anode which is sufficient to maintain a corona field of ionized gas between the cathode and the anode filter element. The anode filter element includes a porous fibrous sheet material having pores in a range of from about 0.1 to about 100 micrometers, with at least a portion of the fibers thereof being uniformly coated with a metal. Also provided is a method of utilizing such apparatus to remove particulate matter from a gaseous medium.

Abstract: The particle collection efficiency of a fibrous filter is significantly increased by imposing a high voltage potential on electrodes placed on either side of the filter. This creates a strong electrostatic field across the filter which electrically enhances the fiber's particle collection ability. The electrostatic field strength, and particle collection efficiency, increase with the voltage employed to establish the electrostatic field. An insulated electrode as the front electrode in combination with a conductive electrode as the rear electrode enables a very high electrical potential to be imposed on the electrodes without resulting in arcing between electrodes. Pre-charging of dust particulates with the same polarity as the insulated electrodes further increase collection efficiency without resulting in a charge buildup in front of the electrodes or a blocking of airflow by particles collecting on the electrodes.

Abstract: A method for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes: catalytically converting a portion of the sulfur dioxide contained within the flue gas to sulfur trioxide, by passing a portion of such flue gas through at least one catalyst containing converter module which is positioned within such a flue gas stream; and selectively varying the quantity of flue gas passing through such module by providing an aspirating force to cause flue gas to be drawn through such a converter module.

Abstract: The present invention relates to an improved spacer assembly for use in an electrostatic precipitator. The electrostatic precipitator collects solid particles carried by a flue gas from a source of combustion. The precipitator includes a plurality of spaced parallel plates for collecting the above mentioned particles by electrostatic attraction of the particles to the plates. Each of the plates has a plurality of stiffeners extending outward from the respective plate. Each stiffener is opposite a like stiffener on the opposed plate. A plurality of spacer assemblies is positioned between opposed plates to hold the plates in a flat attitude and to maintain adjacent surfaces of opposed plates equidistantly spaced from one another. Each of the spacer assemblies includes a spacer having opposite ends abutting a pair of opposed parallel plates adjacent to the respective stiffeners of the plates. An upright is connected to the spacer.