Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
  • B03C3/02—Plant or installations having external electricity supply
  • B03C3/04—Plant or installations having external electricity supply dry type
  • B03C3/12—Plant or installations having external electricity supply dry type characterised by separation of ionising and collecting stations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
  • B03C3/34—Constructional details or accessories or operation thereof
  • B03C3/38—Particle charging or ionising stations, e.g. using electric discharge, radioactive radiation or flames
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
  • B03C3/34—Constructional details or accessories or operation thereof
  • B03C3/38—Particle charging or ionising stations, e.g. using electric discharge, radioactive radiation or flames
  • B03C3/383—Particle charging or ionising stations, e.g. using electric discharge, radioactive radiation or flames using radiation

Definitions

• the present invention relates to an air cleaning apparatus, especially an apparatus for cleaning of air in habitable rooms, offices or working spaces, but also for cleaning of air in other applications, e.g. the discharge air from a vacuum cleaner, the intake air to passenger compartments of cars as well as duct filters in ventilating systems etc. More specifically the invention relates to an air cleaning apparatus that includes a ionizing device for generating iones, said device being provided in a chamber, and an electrostatic dust separator, i.e. a precipitator, and possibly also complementary electrical equipment, e.g. a high voltage unit, an air transporting device etc.
• a ionizing device for generating iones
• an electrostatic dust separator i.e. a precipitator
• complementary electrical equipment e.g. a high voltage unit, an air transporting device etc.
• Known air cleaning devices could be in the shape of two step electro filters having the ionizing device in the shape of a corona discharge electrode that is located in a ionization chamber upstream of the precipitator.
• the walls of the ionization chamber define a well-defined space and inside said space a charge of the particles in the air takes place before the air enters the precipitator part.
• a device for air cleaning in a defined larger air volume is described, e.g. a room.
• a device includes an efficient electrostatic precipitator, i.e. a separator for charged aerosol particles, and an ionizer arranged in such a way that the charge of aerosols takes place in the space, e.g. a room, where the device is located to clean the air.
• an ionizer sufficient charge of the aerosol particles is achieved in order to make the aerosol particles to adhere on the precipitant surfaces of the precipitator when the air passes through said precipitator.
• the present invention has the aim to create an air cleaning device where the charging process corresponds to the charge of aerosols with the aid of an ionizer.
• the aerosols in the air in the space where the device is located are not charged and the electrostatic field in the space is not made stronger.
• the air cleaning device according to the characterizing features of the claims includes a ionizing source arranged in such a way that the generated ions to an essential degree terminate their migration within the device.
• the ionizing source is located in a space, below called ion chamber, that is arranged in such a way that ions generated at the ionizing source almost freely can diffuse away from the source and fill up the entire ion chamber.
• a surprising finding for the device is that there is no need for an ordinary ionization chamber, i.e. a chamber where the charging of aerosols takes place with the aid of a relatively high corona current that is generated between the corona electrode and one or several target electrodes, or a large ionization chamber, i.e. a defined space, e.g. a room where a very low corona current in combination with a long dwell time give the aerosols a certain charge.
• the path of migration of the ions is not only controlled by the electrostatic field but also, as is the case when using an ionizer, by the repelling forces between the ions and also by the movement of the air through the chamber.
• a corona current of a split of a ⁇ A is sufficient to effectively charge the particles in a device for about 400 m 3 air per hour.
• Such a low demand of corona current is close to 1000 times lower than in corresponding traditional two step electro filters and several tens times lower than in the device disclosed in SE-A-9200515- 6.
• the ion migration between the electrodes is controlled mostly by the field strength between the electrodes, thus the migration path of the ions is close to equal with the distance between the electrodes.
• the electrostatic field in the ion chamber is very weak and in certain embodiments fully negligible compared to the repelling forces in the ion cloud generated by the ionizing source, and the influence of the field strength upon the migration of the ions could also be small compared to the influence generated by the displacement of the air volume through the device.
• the migration path of the ions in a device according to the invention is considerably longer than the distance between the ionizing source and the closest precipitant electrode(s) or exitation electrode(s) . Further, their migration velocity through the chamber become essentially lower than in devices with strong electrostatic fields in the ionization chamber. Both these conditions, the longer migration path and the lower velocity, results in a substantially longer dwelling time for the ions in the ionization chamber. Thereby, the likelihood increases for the wanted collisions with the aerosols of the air, this being a circumstance that explains the excellent properties of the device.
• the ionizing source can be designed as a point, short wire, loop or in other previously known ways.
• There are also possibilities to use other known ways to generate ions e.g. via use of UV-light in the ionization chamber, thus also achieving an deodorizing and bacteria-destroying effect.
• This way of generating ions often also generates ozone in a proportional amount. Therefore it is important to use the ions generated in the ion chamberas efficient as possible.
• the device according to the invention will be described below with reference to Figs.1 and 2.
• the ionization chamber 10 is arranged upstream of the precipitator 12, seen in the direction of air through the device.
• the ion chamber 10 defines a well- defined space and should preferably be designed with almost symmetrical cross-section, e.g. round or square.
• a ionizing source 14 is in the disclosed embodiment located closest to the entrance of the ion chamber 10 and is constituted of a point electrode that is suspended by a holder 16, the electrode having its free end pointing in the direction of the air flow, see the arrow 17. Via a very high-ohmic electric circuit (passive resistance elements) the ionizing source 14 is connected to one terminal of a high-voltage source 18.
• a ring-shaped exitation electrode or target electrode 20 is provided, said electrode being electrically connected to the other terminal of the high-voltage source 18 and preferably electrically earthed.
• the exitation electrode 20 is only one way to provide necessary field concentration around the ionizing source.
• the exitation electrode 20 can be designed in several different ways. Common for all these designs is that the exitation electrode 20 should be located in the same plane as or upstream of the ionizing source 14, seen in the air flow direction.
• Another way to exitate the ionizing source 14 is to design the walls 22' of the ion chamber of conductive, semi-conductive or antistatic material 23' and preferably connect these to earth, see Fig.2.
• the entrance portion of the precipitator can contribute to the necessary exitation of the ionizing source.
• the ion chamber 10;10' with accompanying ionizing source 14;14' in a device according to the invention. Common for these are that strong electrostatic fields in the ion chamber 10;10' should be avoided and if possible guarantee free diffusion of the ion cloud in said chamber 10;10' . It is not necessary that the ionizing source 14;14' is arranged at the entrance of the ion chamber 10;10' but it is possible to locate said ionizing source 14;14' closest to the precipitator 12;12', i.e. at the outlet from the ion chamber 10;10'.
• the ionizing source 14;14' can also be electrically and mechanically connected to the precipitator 12;12', e.g. be designed as a point arranged upon someone or some of the voltage-applied electrodes in the precipitator 12;12' , the free end of the point being directed towards the entrance of the ion chamber 10;10'. In most useful embodiments it is recommendable to use only one ionizing source and this source should preferably be located on the axis of symmetry of the ion chamber 10;10'.
• the length of the ion chamber 10;10' i.e. the distance between the entrance and the precipitator 12;12', should not be less than the distance between the ionizing source 14;14' and the closest wall 22;22' in the ion chamber 10;10' but preferably 1-3 times said distance or more. Since the charging of the aerosols in the passing air volume normally is low it is preferable and almost necessary that the precipitator 12;12' is of a design that allows efficient separation. Therefore, it is especially recommendable to use precipitators of the type described in SE- A-9303894-1 and especially SE-A-9403116-8.
• Such precipitators 12 are characterized by a stabilized voltage between adjacent electrode elements since there is a continous discharge between the electrodes of the precipitator. However, this discharge is limited to splits of a ⁇ A per electrode element since the electrodes of the precipitator are of high-resistive materials that often are unexpensive and environment friendly, e.g. based upon cellulose.
• SE-A-9403116-8 where the repelling electrode elements are coated with an insulating layer in order to further increase the voltage between the electrode elements and also make them moisture-proof and enable the introduction of stabilizing distance elements between the electrode elements.
• the entrance of the device is provided in the shape of a grate 24 of electrically insulating material, said grate 24 allowing the air flow to bypass.
• the ionizing source is located closest to the precipitator of the device it can be a benefit if the entrance grate 24 is made of an ion leaking material, e.g. earthed sheet metal where the migration of the ions are terminated.
• the exitation electrode can also be provided upstream of the grate 24, seen from the ionizing source 14, said exitation electrode preferably being made out of perforated sheet metal.
• the entrance of the ion chamber 10' could also be designed in such a way that a plate 25' or disc, with the ionizing source 14' located in its middle, is arranged transverse to the direction of the air flow at a distance from the ends of the walls 22' of the ion chamber 10'.
• the air enters the ion chamber 10' via the opening 11' between the top plate 25' and the ends of the walls 22' of the ion chamber (Fig.2).
• a precipitator according to SE-A-9403116-8 makes it possible to design a duct filter as a disposable electrostatic precipitator.
• Traditional electrostatic precipitators where the electrode elements are made out of aluminum plates have been found to be impractical to handle in ventilating ducts, e.g.
• the necessary charging of aerosols can take place in a ion chamber with relatively small extension in_ direction of the duct, an efficient two step air filter can be created that accomodates in spaces adapted for traditional mechanical filter cassettes in ventilating systems.
• the separation part can preferably be designed out of simple, environment friendly materials. It is of course also preferable to manufacture the ion chamber of the same type of material as the separation part of the device, e.g. of cellulose based materials.
• the walls of the ion chamber can also be a part of the casing of the separator. Thereby, after contamination the whole interior of the device can be exchanged.
• the ionizing source partly due to the low demand of corona current, has a very simple design low-quality isolation materials, e.g. cellulose plastic, can be used for the securing of the ionizing source. Since it also is simple to electrically connect the ionizing source to the high-voltage source, the entire device (i.e. precipitator, ion chamber and ionizing device) can be designed as a disposable product, i.e after contamination the cleaning part of the device (except the high-voltage source) is replaced by a new one and the consumed part is burnt or recycled.

Landscapes

• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Electrostatic Separation (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=20395490

Family Applications (1)

Country Status (4)

Families Citing this family (9)

Family Cites Families (5)

• 1994
  • 1994-10-05 SE SE9403369A patent/SE9403369D0/sv unknown
• 1995
  • 1995-10-03 WO PCT/SE1995/001126 patent/WO1996011060A1/en not_active Application Discontinuation
  • 1995-10-03 EP EP95934379A patent/EP0784510A1/en not_active Withdrawn
  • 1995-10-03 AU AU36912/95A patent/AU3691295A/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events