Abstract: A discharge unit (30) and a heat exchanger (20) are disposed in an air passageway (15). In the discharge unit (30), a rod-like discharge electrode (31) and a plate-like counter electrode (32) are disposed perpendicular to the flow of air, and lie along the heat exchanger (20). Upon application of voltage to both the electrodes (31, 32), streamer discharge is performed between the electrodes (31, 32), whereby an active species capable of decomposition of a component to be processed is produced.

Abstract: The present invention relates to a device and method for separating particulate material from a gas flow, comprising a substantially elongate housing provided with a peripheral wall and an inlet opening for admitting the gas flow with particulate material into the housing; a number of electrodes extending in the housing up to a predetermined radial distance from the peripheral wall; and an outlet opening arranged downstream in the housing for discharging the gas flow, wherein the outlet opening extends from the axial centre line of the housing to a point some radial distance from a peripheral wall of the housing, and wherein the particulate material is guided into an intermediate space between the outlet opening and the peripheral wall.

Abstract: A charged multilayer filter includes a hydrocharged filtration layer containing a plurality of intertwined nanofibers that have a finite length of about 12 to about 300 mm, atop a porous roll-to-roll processable support layer.

Abstract: A method of operating a filtration system that filters flue gas, which includes particulate matter and a gaseous pollutant. The filtration system may include a fabric filter, which is cleaned with periodic pulse cleanings, a discharge electrode upstream of the fabric filter, which imparts an electric charge to at least some of the particulate matter before the particulate matter collects on the fabric filter, a sorbent, which is injected into the flue gas upstream of the fabric filter and absorbs at least some of the gaseous pollutant, and a fan, which draws the flue gas through the fabric filter. The filtration system may have a pulse cleaning interval setting that may be manipulated by an operator of the filtration system. The pulse cleaning interval setting may be the time between the pulse cleanings.

Abstract: An air conditioning apparatus includes a cabinet having air inlet and outlet openings and an intense field dielectric air filtration system disposed in the cabinet between the inlet and outlet openings. The filtration system includes a field charging unit and a filter unit. The filter unit may be mounted for removal from the cabinet on spaced apart support brackets connected to the cabinet or to a frame of the field charging unit. Electrical contact elements may be supported by the support brackets for engagement with corresponding contact elements on the filter unit and charging unit for establishing electrical communication between a power supply and the charging unit and filter unit, respectively. A shorting bar is aligned with the contact members on the filter unit for discharging high voltage potential upon removal of the filter unit from the cabinet.

Abstract: A multi-stage collector for multi-pollutant control that contains alternating narrow and wide sections with glow discharge electrodes in some narrow sections, a uniform electric field in wide sections for collecting particles charged by the glow discharge and streamer discharge electrodes in wide or narrow sections that convert and destroy harmful gaseous pollutants such as SO2, NOx and volatile organic compounds as well as convert heavy metals such as mercury into a particulate form. Steady state streamer discharge is supported by non-pulsed power supply. The streaming discharge can convert the polluting gases into nitric and sulfuric acid which can be removed by combining it with ammonia to form solid salts.

Abstract: The air clarifying apparatus includes a negative ion generator and an indoor air circulator. It further includes an ozone generator having a capability of maintaining the average concentration value of ozone in an indoor atmosphere at 0.02 to 0.05 ppm, while the average concentration value of negative ions in the vicinity of the blowout port of the negative ion generator is maintained at 200,000 to 1,000,000 pieces/cc. With this configuration, the negative ions coexist with ozone having a low concentration.

Abstract: A device for purification of a gas flow containing condensable vapors including a shell (7) defining a sealed volume, a cooler to quench the gas flow, a rotating assembly (42) having a rotor (44) and a cylindrical separation and filtration skirt (54) composed of serrated circular rings (56) mounted on the rotor and rotating with it; a support tube (48) mounted on the rotor (44) and carrying a turbulator-scraper device (50) a cylindrical electrode (94) surrounding the separation and filtration skirt (54) and a central counter-electrode (78) to create an electrostatic field in the shell (7), a purified gas outlet tube, a condensates outlet pipe (40) and impact separation plates (64) fixed on the rings of the skirt.

Abstract: In an air purifier including a streamer discharge part (40) generating plasma by streamer discharge, a catalytic part (34) promoting the treatment of air using active species contained in the plasma and a dust collecting part (33) collecting dust in the air, the streamer discharge part (40), the dust collecting part (33) and the catalytic part (34) are arranged in sequence from the upstream side of the air flow to allow the entire face of the catalytic part (34) to effectively work and also permit the elimination of fungi and the inactivation of allergens in a dust collecting part (33).

Abstract: The present invention provides an air filtration cartridge suitable for use in the treatment of air in a forced airflow air supply system. The cartridge comprises an inner casing having an upstream stage defining a chamber having an inlet for receiving a forced airflow. The chamber has an outlet which leads into a downstream stage comprising a filter holder and mounting a high airflow electrostatic filter. Inside the chamber is a low power coronal discharge ozone generator device.

Abstract: An air purifier includes an outer case having an air purifying cavity, an ionizer module, and an ozone reduction module. The ionizer module includes a power unit and an ionizing electrode. The ozone reduction module is electrically connected to the power unit for generating heat within the air purifying cavity, wherein when a temperature within the air purifying cavity reaches a preset temperature, a level of ozone generated by the ionizing electrode unit is substantially minimized and controlled for preventing excess generation of ozone.

Abstract: Systems for and methods of providing air purification and cleaning in combination with odor elimination in a single unit, such as a tabletop unit for home or office use, are disclosed. The air cleaning device includes a housing, an air intake port, an air movement mechanism, a pre-ionizer, a filter, a post-ionizer, an air exhaust port, and a flow chamber for holding a compound such as an odor elimination supply. An air movement mechanism, ozone removal mechanism, and/or filter/odor elimination assembly may also be present.

Abstract: An air purifier includes an outer case having an air purifying cavity, an ionizer module, and an ozone reduction module. The ionizer module includes a power unit and an ionizing electrode. The ozone reduction module is electrically connected to the power unit for generating heat within the air purifying cavity, wherein when a temperature within the air purifying cavity reaches a preset temperature, a level of ozone generated by the ionizing electrode unit is substantially minimized and controlled for preventing excess generation of ozone.

Abstract: A pollution abatement apparatus comprises an electrified filter bed preceded by a cyclonic mix chamber to remove wood fines and fly ash in a flue gas stream from a wood chip dryer heated by hot gas from an energy system that includes a wood waste combustor. The cyclonic mix chamber has dual inlets, one supplied with flue gas from the dryer and the other supplied with hot gas from the energy system.

Abstract: A system for separating oxygen from air operates at a pressure less than atmospheric. The oxygen separation system includes an entry port for ambient air, and at least two separate exhaust ports through which separate exhaust streams are drawn by separate suction sources. The oxygen separation system further includes a low-energy ionization portion that favors creation of molecular oxygen ions, and a higher-energy portion disposed between the ionization portion and one of the exhaust ports. A plurality of gas-permeable electrodes are charged to different voltages to provide the different portions inside the separator. An exhaust stream taken from the anode side of the separator is enriched in oxygen relative to ambient air.

Abstract: An indoor air quality system for a structure is provided. The indoor air quality system includes a ventilation system and a corona discharge apparatus. The ventilation system directs air through the structure. The corona discharge apparatus is positioned within the ventilation system and is operable to filter the air and to move the air through the ventilation system.

Abstract: An apparatus for removing particulate matter from a biomass combustion gas stream, the apparatus having a mist-producing element that mixes a gas stream entering the apparatus with liquid droplets; a Wet Electrostatic Precipitator (WESP) section that includes ionizing electrodes that electrically charge the particulate matter and the intermixed liquid droplets and collecting surfaces under the influence of an electrical field which attract and remove electrically-charged particulate matter and intermixed liquid droplets from the gas stream; and a scrubbing section that provides for additional scrubbing of the gas.

Abstract: A plate heat exchanger for exchanging heat between a first air stream and a second air stream includes a plurality of plates limiting first and second exchange chambers which are serially arranged in a transversal direction with respect to the plates. A first air stream of outside air passes through the first exchange chambers, a second air stream originating from ventilated rooms passes through the second exchange chambers. The heat exchanger further includes an ionization device for ionizing particles entrained in the first air stream so that the particles deposit at conductive plates of the first exchange spaces, a water distribution system for periodically discharging water into the first exchange spaces for cleaning the plates of the heat exchanger from deposited particles, and a water collection device for discharging collected water.

Abstract: Disclosed is an air purifier with a small size, having an excellent air purifying capacity, capable of preventing a large amount of ozone from being generated, the ozone harmful to a human body. The air purifier includes a case, a pair of discharge electrodes provided at upper and lower parts of the case, a ground electrode provided between the pair of discharge electrodes, a pair of insulating dielectric layers provided on upper and lower surfaces of the ground electrode, and a power source coupled respectively to the ground electrode and the discharge electrode so as to supply voltage thereto.

Abstract: A ventilation system for a building is provided. The ventilation system includes a pair of passages between the interior and exterior of the building and at least one corona discharge apparatus for drawing fluid through the passages. The ventilation system may also include an energy recovery ventilator for transferring energy, humidity or the combination of energy and humidity between the fluid flowing through the two passages. Variable flow rates through the passages are provided by varying the voltage to the corona discharge apparatus. In addition, the corona discharge apparatuses may filter the air flowing through the passages.

Abstract: An air conditioning device for heating and/or an environment is provided. The air conditioning device includes a heat exchanging apparatus, a passage, and a corona discharge apparatus. The passage is in thermal communication with the heat exchanging apparatus and extends between an inlet and an outlet. The corona discharge apparatus is disposed within the passage to draw a fluid from the environment into the passage through the inlet, move the fluid through the passage to permit the heat exchanger to remove or heat the fluid, and expel the fluid through the outlet into the environment. As such, the environment is cooled or heated. Embodiments of the present invention include package terminal air conditioners (PTACs), room air conditioners (RACs), and mini-split heating and cooling systems.

Abstract: An air filter device for an air exhauster includes at least one static electricity dust-collecting module, at least one water-cleaning module and a casing. The static electricity dust-collecting module is operated to generate static electricity for electrically attracting greasy dirt and dust filled in exhaust air. The water-cleaning module mechanically connects to at least one side of the static electricity dust-collecting module, and includes a plurality of guiding members each forming a longitudinal groove for guiding water in wetting and washing greasy dirt and dust filled in exhaust air.

Abstract: Manganese is added to a combustion fuel, combustion air, or the resulting combustion exhaust gas in order to improve the efficiency of an electrostatic precipitator in collecting the resulting fly ash. Further, manganese or other flame suppressant is added to a fuel, and/or combustion air, or combustion exhaust gas stream in order to reduce back-corona discharge that could otherwise occur in an electrostatic precipitator.

Abstract: A method of removing mercury from a coal fired power plant exhaust gas includes passing the exhaust gas through a bulk particle filter to remove coarse particles, introducing powdered activated carbon into the exhaust gas downstream of the bulk particle filter, introducing mercury laden powdered activated carbon containing exhaust gas into a fine particle filter to separate the mercury containing powdered activated carbon from the exhaust gas, separating the powdered activated carbon from the mercury at an elevated temperature in an inert gas environment and recirculating the separating powdered activated carbon into the exhaust gas upstream from the fine particle filter. The desorption is preferably effected at a temperature of about 300 to 500° C. for about 5 to 60 minutes. The method is adapted to remove mercury which may be on the order of about 1 to 1000 ppm to 1 to 10 micrograms/cubic meter of exhaust gas. Corresponding apparatus is provided.

Abstract: A method and apparatus for preventing contamination of a substrate or a substrate surface, and particularly relates to prevention of contamination of raw materials, semi-finished products, base materials of products and substrate surface in a high-tech industry such as an in the production of semiconductors and liquid crystals. A gas coming into contact with a base material or substrate is purified by dust removing apparatus and adsorption and/or absorption apparatus so that the concentration of fine particles in the gas is below class 1,000 and a non-methane hydrocarbon concentration is below 0.2 ppm. Thereafter, the base material or the substrate surface is exposed to this gas.

Abstract: The present invention provides a combination filter for filtering fluids comprising a flow channel particulate filtration media having a first face and a second face and a gas adsorbing filtration media. The flow channel particulate filtration media comprises a plurality of flow channels directed in flow direction and defined by inner surfaces. The flow channels having inlet openings through the first face and outlet openings through the second face of the flow channel particulate filtration media. The inner surfaces of said flow channels at least in part are provided with structures protruding therefrom and forming or extending into the flow channels or an electrical charge or a combination of both. The said gas adsorbing filtration media comprises a pad having a first face and a second face and width and length dimensions orthogonal with respect to each other and each individually to the flow direction and having a thickness dimension in flow direction.

Abstract: Pollutants in a flue gas stream from a dryer of products, such as wood chips, are removed by a pollution abatement system that includes an electrified filter bed unit for removing solid particulates. To prevent deteriorated operation of the electrified filter bed unit due to condensation of volatile organic compounds, the flue gas stream is heated, prior to admission to the electrified filter bed unit, to a temperature sufficient to convert condensable liquid aerosols to a gaseous state. The electrified filter bed unit then removes solid particulate selectively without collecting condensable organics. After the flue gas stream has passed through the electrified filter bed unit, gaseous pollutants can be removed by an oxidation process, for example.

Abstract: A wall is formed by adding a predetermined amount of binding agent and water to volcanic ash sediment, which is comprised of mineral silicate including at least silicic acid and aluminum oxide, kneading them, and applying to an arbitrary plane. Through a natural reaction of positive ions included within mineral silicate and moisture included within the atmospheric air, thereby exchanging ions, minus ions are generated on an application plane. The amount of minus ions generated is, in a unit volume, between three and six times as many as that of the minus ions generally included in the atmospheric air. The combination of this application plane and humidity control apparatus is used as a minus ion generation system through adjustment of amount of moisture included within the atmospheric air so as to control the ion exchanging rate. In the case where said volcanic ash sediment includes titanium oxide, it reacts with hydrogen or oxygen generating active oxygen species or oxygen free radical.

Abstract: The invention relates to a gas supply for an electrostatic filter and an electrostatic filter arrangement which has an electrostatic filter and a gas supply. Here, the gas supply has an incoming flow channel of constant cross-sectional area, a gas inlet hood with cross-sectional area expanding in the direction of the electrostatic filter, and an admixture arrangement for a conditioning means, wherein at least one flow distributor is arranged in the expanded cross-sectional region of the gas inlet hood. Characterizing features include a first vortex arrangement generating a leading-edge vortex arranged in the incoming flow channel, a second vortex arrangement generating a leading-edge vortex arranged in the gas inlet hood before the flow divider in the gas flow direction, and the admixture arrangement arranged in the region of one of the two vortex arrangements.

Abstract: The present invention provides a method and apparatus for removing trace contaminants from a gas stream or flue gas. In one embodiment, the present invention an apparatus for removing a trace contaminant from a gas stream, comprising a gas duct configured to receive a gas stream comprising a trace contaminant; a plurality of substrates disposed within the gas duct; a trace contaminant sorbent disposed on at least a portion of each of the substrates; an isolation device for separating the portion of each of the substrates from the gas stream; and a regenerator for regenerating the trace contaminant sorbent. In another embodiment, the present invention provides a method for removing a trace contaminant from a gas stream.

Abstract: In an apparatus for the purification of a gas which apparatus includes a three section conduit with an ionization and cleaning section in which particles contained in water-saturated air are ionized and then conducted through a chamber with grounded walls so that part of the particles are deposited on these walls, an additional cleaning section which includes grounded tubes past which the gas is conducted to remove additional charged particles and a filter section in which dry remaining fine particles are removed from the gas stream, the deposited particles are flushed from all three sections and the flushing water including the particles is cleaned and recycled.

Abstract: An air cleaning apparatus is disclosed which, in one embodiment, has: an inlet for ambient air; an outlet for purified air; a mechanism for the uptake of a scrubbing liquor and for the removal of impurities dissolved or dispersed in the ambient air by contact with said scrubbing liquor; an inlet for feeding a scrubbing liquor from a scrubbing liquor feeding tank; an outlet for discharging used scrubbing liquor; and a blower for drawing ambient air into the apparatus, flowing the air through the apparatus and discharging the purified air from the apparatus. A kit including an apparatus as described above and a refill of scrubbing liquor ingredients, or of a scrubbing liquor concentrate or of a ready-to-use scrubbing liquor is also disclosed.

Abstract: A method for efficiently removing vapor-phase contaminants from gas streams is described. A powdered adsorbent such as activated carbon is ground into a fine powder by wet grinding to form a slurry. Chemicals are added to the slurry to impregnate the sorbent to enhance sorbent effectiveness. The slurry chemical mixture is sprayed into the gas stream in the form of small droplets which evaporate to produce an aerosol of fine adsorbent particles. Vapor-phase contaminants in the gas stream adsorb onto the fine adsorbent particle surfaces and the adsorbent particles are removed from the gas stream by a conventional particle collection method.

Abstract: The present invention discloses a process for removing undesired particles from a gas stream including the steps of contacting an additive containing nitrate and/or nitrite anions with the gas stream; collecting the undesired particles and additive on a collection surface to form an aggregate on the collection surface comprising the additive and undesired particles; and removing the agglomerate from the collection zone. The anions can be compounded with one or more of potassium, sodium, calcium, and aluminum. In a preferred composition, the anion(s) is/are compounded with potassium. The process may be applied to electrostatic precipitators to improve undesired particle collection efficiency.

Abstract: The present invention includes a filtered mask enclosure having an exterior portion and interior regions within the exterior portion such that the interior regions have a filtering region and a purging region connected to the filtering region. The present invention further includes a method of removing a first contaminant in a gas phase, a second contaminant in a solid phase, and a third contaminant having an electrical charge from a purge gas and flowing the purge gas through a vicinity of a mask while exposing a wafer with light through the mask.

Abstract: There is provided a process for trapping particulate matter in a gas stream exiting a combustion equipment comprising providing a combustion equipment with one or more exits for exhaust gases, each exit connected to one or more ducts, and placing at least one particulate trap in each duct, wherein the particulate trap is removable and/or replaceable while the combustion equipment is online.

Abstract: It is disclosed a combined system for the elimination of pollutants from gaseous effluents of the type that comprises means for carrying out at least one electronic bombardment operation and means for carrying out at least one electrostatic interaction operation, in which a heat diffusion and molecular destabilization operation is performed as a previous treatment in order to restrict the flow of gases in such a way that it causes the gas molecules and suspended particles to tend to split up and electronically destabilize at the time that the temperature of the same gases is reduced; and/or a magnetic molecular rearrangement operation is carried out prior to each electrostatic interaction operation, consisting of subjecting the gases to a magnetic field having such a force that achieve a rearrangement of the sub-particles and heavier molecules thus achieving a selective separation that prepares the gaseous stream for the electrostatic interaction operation.

Abstract: A method for cleaning air utilizing an air cleaner which is smaller than conventional air cleaners, wherein a filter is formed on the peripheral portion of a disk and the filter is bent into a wave-shape such that irregularities of the wave are formed in the radial direction of the disk, so that air existing on the inside area of the disk is discharged to the outside of the disk through the filter.

Abstract: The present invention includes a filtered mask enclosure having an exterior portion and interior regions within the exterior portion such that the interior regions have a filtering region and a purging region connected to the filtering region. The present invention further includes a method of removing a first contaminant in a gas phase, a second contaminant in a solid phase, and a third contaminant having an electrical charge from a purge gas and flowing the purge gas through a vicinity of a mask while exposing a wafer with light through the mask.

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: An apparatus for removing particles from a gas in a high purity flowing gas system is provided which includes a flow tube inserted inline in the flowing gas system having an inlet and an outlet, a pressure sealed, electrically insulated feed-through integral to the flow tube, an emitter inserted through the feed-through into the flow tube to create a plasma in the gas to charge particles in the gas, and a collector surface in proximity to the emitter; whereby an electric field between the emitter and the collector surface draws the particles in the gas to the collector surface.

Abstract: A ceramic membrane structure and method for separating oxygen from an oxygen containing feed at temperatures above about 600° C. The membrane is provided with a dense layer and one or more active porous layers. The dense layer contains at least a mixed conducting material and the active porous layer is formed of a mixture having an ion conducting phase capable of predominantly conducting oxygen ions and a mixed conducting phase capable of conducting both said oxygen ions and electrons. The ion conducting phase is present within the mixture in an amount greater than a percolation threshold and the mixed conducting material and phase have a greater electronic conductivity than ionic conductivity.

Abstract: A condensing wet electrostatic precipitator for cleaning hot gases is constructed of collection electrode modules which establish longitudinally extending collection electrodes and a cooling jacket, each collection electrode module having a configuration including at least one part-tubular section and a cooling fluid chamber integral with the part-tubular section for containing cooling medium for cooling the part-tubular section. In some arrangements, the collection electrode modules are spaced apart laterally to enable the passage of the hot gases through the collection electrodes in a direction transverse to the longitudinal direction in which the collecting electrodes extend.

Abstract: The method and apparatus of the present invention are directed to conditioning particulate-containing gas streams using novel additives. The additive is an organometallic salt, preferably of a carboxylic acid, that decomposes in the gas stream to produce mobile metal compounds that significantly reduce the resistivity of the particles. The additive is particularly effective under hot-side conditions when used to condition particles to be collected by an electrostatic precipitator.

Abstract: This invention relates to a method and a device for agglomerating particles in a gaseous flow through an acoustical agglomeration chamber (3). According to the invention a portion of the flow at the outlet of the chamber is selectively extracted by preferring larger particles, and is re-injected into the inlet of the chamber.

Abstract: An electrical apparatus includes a reaction chamber. A stream of contaminated gasses flows through the chamber. An elongated coronating electrode is positioned in the reaction chamber for producing a corona discharge within the chamber. A multi-stage Fitch generator connected to the electrode produces a high level, rapidly pulsating voltage in the electrode. Controlled amounts of an inert gas or inert gas-air mixture are combined with the contaminated gases to provide a high concentration of inert gas in the reaction chamber. In the inert gas-enriched atmosphere, the pulsating corona discharge produces a high concentration of metastable intermediates that greatly increase the rate of chemical conversion of the contaminants. Switching circuitry allows the pulsating voltage output of the Fitch generator to be superimposed on a constant direct current voltage in the electrode, setting up an electrostatic field in the reaction chamber for removing conversion byproducts from the gas stream.

Abstract: A condensing wet electrostatic precipitator is constructed of collection electrode modules which establishing collection electrodes and a cooling jacket, each collection electrode module having a configuration including at least one part-tubular section and a cooling fluid chamber integral with the part-tubular section for containing cooling medium for cooling the part-tubular section, the configuration of each collection electrode module being such that upon assembly of the collection electrode modules into an assembly of juxtaposed collection electrode modules the part-tubular sections are juxtaposed to establish at least one corresponding generally tubular collection electrode comprised of the juxtaposed part-tubular sections and the discrete cooling fluid chambers are juxtaposed to establish a corresponding cooling jacket comprised of the juxtaposed discrete cooling fluid chambers.

Abstract: An electrostatic bag filter unit is formed of a plurality of sections arranged in series. One section is a bag filter section containing a plurality of parallel elongated filter fabric bag elements extending across and traverse to a gas flow path therethrough and a plurality of grounded, electrically-conductive support frames, each support frame being internal to and supporting one of the filter fabric bag elements. Optionally, the bag filter section may further include a plurality of non-discharging electrodes disposed parallel to and interspersed among the filter fabric bag elements. A filter precharger section is located immediately upstream of and contiguous with the bag filter section and is formed of a linear array of alternating corona discharge electrodes and grounded electrodes arranged perpendicular to the gas flow path.

Abstract: The dust concentration of the flue gas leaving an electrostatic precipitator and introduced into an absorption tower of a desulfurizer is adjusted to a level of 100 to 500 mg/Nm.sup.3. At the same time, a dust slurry having a higher dust concentration is separated and withdrawn from the slurry within the aforesaid absorption tower, and then subjected to a solid-liquid separation treatment. Thus, solid matter containing dust at a high concentration is extracted and discharged out of the system of the desulfurizer.

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.