EP0452387B1 - Filter zum abtrennen von teilchen aus gasen - Google Patents

Filter zum abtrennen von teilchen aus gasen Download PDF

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Publication number
EP0452387B1
EP0452387B1 EP90901699A EP90901699A EP0452387B1 EP 0452387 B1 EP0452387 B1 EP 0452387B1 EP 90901699 A EP90901699 A EP 90901699A EP 90901699 A EP90901699 A EP 90901699A EP 0452387 B1 EP0452387 B1 EP 0452387B1
Authority
EP
European Patent Office
Prior art keywords
filter
gases
members
dust
fibres
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90901699A
Other languages
English (en)
French (fr)
Other versions
EP0452387A1 (de
Inventor
Rolf Hunt
Peter Odenmo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Secretary of State for Defence
ABB Technology FLB AB
Original Assignee
UK Secretary of State for Defence
ABB Flaekt AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by UK Secretary of State for Defence, ABB Flaekt AB filed Critical UK Secretary of State for Defence
Priority to AT90901699T priority Critical patent/ATE103209T1/de
Publication of EP0452387A1 publication Critical patent/EP0452387A1/de
Application granted granted Critical
Publication of EP0452387B1 publication Critical patent/EP0452387B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B03C3/14—Plant or installations having external electricity supply dry type characterised by the additional use of mechanical effects, e.g. gravity
    • B03C3/155—Filtration

Definitions

  • the present invention relates to a filter for separating particles from gases by screening, comprising bag-shaped filter members made of textile filter material, each filter member having at least one opening for discharging the gases flowing through the filter material of said filter member, pervious stiffening means arranged inside said filter members, and electrically conductive means arranged inside and outside the filter members for charging said fibres, the electrically conductive means inside the filter members consisting of the said stiffing means, and the electrically conductive means outside the filter members consisting of electrodes.
  • a filter of this type is disclosed in US-A-3,910,779 and when such filters are used for cleaning dust-laden gases, for example flue gases from refuse incineration plants, the dust accumulated on the outsides of the filter members should form dust cakes as thick as possible. This is due to the fact that the cleaning effect of the filter increases with the thickness of the dust cake; the longer the distance the gases have to travel through the filter members, the greater the chance of collecting the dust contained in the gases.
  • these filters are provided with electrically conductive means that enhance the dust particles ability to form large dust particles the dust cakes formed by the dust particles will be porous. This means that the resistance and consequently the pressure drop across the dust cakes will be moderate even for thick dust cakes. Consequently, the thickness of the dust cakes will not be limited by the pressure drop but by the density of the dust cakes. If the density is too high the dust cakes have a tendency to fall off the filter members before they have become thick enough for producing a satisfactory efficiency.
  • the filter is used in a plant for cleaning flue gases from a refuse incineration plant, it is especially difficult to maintain thick dust cakes on the filter members, since gaseous hydrogen chloride and, if the refuse is humid, considerable amounts of water vapour are formed.
  • lime is supplied upstream of the filter in a contact reactor, the hydrogen chloride will react with the lime and form calcium chloride which is hygroscopic.
  • the presence of calcium chloride causes the dust cakes to attract water vapour, making them compact, heavy and sticky.
  • the tendency of the dust cakes to fall off the filter members will be considerable so that the thickness of the dust cakes will not be sufficient for producing a satisfactory separation of the particulate and gaseous impurities of the flue gases, and the filter will be difficult to clean.
  • the filter operating temperature is in this case at a level too low for the remaining process.
  • a powdery catalyst material is applied to the outsides of the filter members, and ammonia is added to the gases ahead of the filter, the latter may be used for catalytic reduction of nitrogen oxides in the gases.
  • the catalyst material in many cases has such a high density that the catalyst material layers formed on the outsides of the filter members become so heavy that they fall off the filter members before they have become thick enough for a satisfactory nitrogen oxide reduction.
  • the object of the present invention is, therefore, to provide a gas cleaning filter which imparts to the dust cakes or the catalyst material layers a sufficient thickness to obtain a satisfactory separation of the particulate and gaseous impurities of the gases in all filter applications, i.e. also in a plant for cleaning flue gases from a refuse incineration plant.
  • a voltage of 0-50 kV, especially 20 kV, has been applied between the stiffening means and the electrodes.
  • the stiffening means may be earthed, and to the electrodes a voltage of 0-50 kV, preferably 20 kV, may be applied.
  • the electrodes may be earthed, and to the stiffening means a voltage of 0-50 kV, preferably 20 kV, may be applied.
  • the textile filter material preferably is of PTFE (TEFLON).
  • the fibres hanging loosely from the filter medium preferably consist of PTFE (TEFLON) and usually have a length of 10-50 mm, preferably 30 mm, and a thickness smaller than or equalling 0.2 mm, preferably 0.1 mm.
  • Fig. 1 is a longitudinal sectional view of a bag filter according to the invention.
  • Fig. 2 is an enlarged part sectional view of Fig. 1.
  • the bag filter 1 shown in Fig. 1 comprises a filter housing 2, an inlet 3 for the gases, e.g. flue gases from a refuse incineration plant, to be cleaned, and an outlet 4 for the cleaned gases.
  • a plate 5 divides the inside of the filter housing into a raw gas chamber 2a and a clean gas chamber 2b communicating with the inlet and the outlet, respectively.
  • the bag filter usually comprises 100-500, especially 300, filter bags 7 arranged in longitudinal and transverse rows. At their upper open end, these filter bags are detachably mounted in holes 6 in the plate 5 by means of a conventional attachment (not shown).
  • the length of the filter bags is 3-5 m, usually 5 m, and their diameter is 100-200 mm, usually 125-130 mm.
  • the longitudinal distance between two adjacent filter bags 7 is 300-500 mm, usually 400 mm.
  • the transverse spacing is 300-500 mm, usually 400 mm.
  • Electrodes 8 are arranged between the filter bags such that one electrode is positioned at each point of intersection between the diagonal lines of four longitudinally and transversely adjacent filter bags.
  • the electrodes have the same length, but are thinner than the filter bags and in the form of round rods. Their diameter is 20-40 mm, usually 30 mm.
  • the electrodes are inserted through holes (not shown) in the plate 5 and are kept in place by means of holders (not shown), such that they have no contact with the plate 5. A voltage of 20 kV has been applied to the electrodes via their holders.
  • Nozzle tubes 9 with nozzles 10 are transversely arranged over the filter bags 7, such that one nozzle is positioned over the upper open end of each filter bag. Consequently, each filter bag, when being cleaned, receives a direct injection of cleaning air supplied to the nozzles from a pressure tank (not shown) via the nozzle tubes. The cleaning air is supplied to one nozzle tube at a time, in the form of a short strong pulse of compressed air.
  • the nozzle tubes are detachably mounted in the clean gas chamber 2b for exchange of filter bags. For the same reason, the top of the filter housing 2 is provided with a number of doors 11 positioned over the nozzle tubes 9.
  • the bottom of the filter housing 2 is funnel-shaped to serve as a dust pocket for collecting the dust separated from the raw gas.
  • the dust is then fed to a dust container (not shown) by means of a screw conveyor (not shown).
  • the fitter bags 7 are mounted round stiffening means 12 in the form of cages which, in conventional manner, are shaped such that they do not interfere with the movement of the gas flow through the filter bags. Furthermore, these cages are earthed via the plate 5.
  • Fig. 2 It is also apparent from Fig. 2 that the outsides of the filter bags are provided with fibres 13 hanging loosely from the filter material of the filter bags. These fibres are usually made of the same textile material as the filter. Since such materials can withstand higher operating temperatures, when surrounded by thick dust cakes, the choice of the material is determined by the filter operating temperature and the thickness of the dust cake 14 forming round the fibres 13.
  • Acryl is a suitable material for operating temperatures of 60-130°C polyester for temperatures of 130-150°C RYTON for temperatures of 150-180°C, and TEFLON for temperatures of 180-240°C.
  • the length of the fibres is 10-50 mm, preferably 30 mm, and the thickness is smaller than or equalling 0.2 mm, preferably 0.1 mm.
  • the bag filter operates as follows.
  • the dust-laden gases to be cleaned in the bag filter are conducted, under a certain excess pressure, into the raw gas chamber 2a the filter housing 2 via the inlet 3. Since the inlet is positioned at the upper end of the filter bags, the gases will flow vertically downwards along the outsides thereof (see Fig. 1), i.e. leading of the gases co-acts with gravity. Consequently, the dust released by the cleaning of the filter bags 7 will not be recycled to the bags by the incoming gases.
  • the cleaned gases flow from the inside of the filter bags to the clean gas chamber 2b and, via the outlet 4, to a chimney (not shown) and are discharged into the atmosphere (see Fig. 1).
  • the fibres hanging loosely on the outsides of the filter bags will also have a reinforcing effect on the dust cakes of the filter bags, such that the heavy dust cakes usually formed on the outsides of the filter bags when the filter is used as an NO x -catalyst, will remain on the filter bags.
  • a different voltage than 20 kV may of course be applied between the electrodes and the cages, but it should preferably be 0-50 kV to make it possible to obtain maximum results.
  • the round rod electrodes may, of course, also be of square or spiral form.

Landscapes

  • Filtering Of Dispersed Particles In Gases (AREA)
  • Electrostatic Separation (AREA)

Claims (6)

  1. Filter zum Abscheiden von Teilchen aus Gasen durch Siebung, umfassend sackförmige Filterelemente (7) aus Filtermaterial aus Webstoff, wobei jedes Filterelement zumindest eine Öffnung zum Austragen der durch das Filtermaterial des genannten Filterelements strömenden Gase, durchlässige, innerhalb der Filterelemente angeordnete Versteifungsglieder (12) und elektrisch leitende Glieder (12, 8) aufweist, die innerhalb und ausserhalb der Filterelemente angeordnet sind, wobei die innerhalb der Filterelemente (7) angeordneten, elektrisch leitenden Glieder aus den genannten Versteifungsgliedern (12) bestehen und die ausserhalb der Filterelemente (7) angeordneten, elektrisch leitenden Glieder aus Elektroden (8) bestehen, dadurch gekennzeichnet, dass die Aussenseiten der Filterelemente (7) mit Fasern (13) versehen sind, die von dem Filtermaterial lose hängen, und dass die genannten Fasern von den elektrisch leitenden Gliedern (12, 8) geladen sind.
  2. Filter nach Anspruch 1, dadurch gekennzeichnet, dass eine Spannung von 0-50 kV, vorzugsweise 20 kV, zwischen den Versteifungsgliedern (12) und den Elektroden (8) angelegt ist.
  3. Filter nach Anspruch 2, dadurch gekennzeichnet, dass die Versteifungsglieder (12) geerdet sind, und dass eine Spannung von 0-50 kV, vorzugsweise 20 kV, an den Elektroden (8) angelegt ist.
  4. Filter nach Anspruch 2, dadurch gekennzeichnet, dass die Elektroden (8) geerdet sind, und dass eine Spannung von 0-50 kV, vorzugsweise 20 kV, an den Versteifungsgliedern (12) angelegt ist.
  5. Filter nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das Filtermaterial aus PTFE (TEFLON) besteht.
  6. Filter nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die vom Filter lose hängenden Fasern (13) aus PTFE (TEFLON) bestehen und eine Länge von 10-50 mm, vorzugsweise 30 mm, und eine Dicke haben, die kleiner ist als 0,2 mm, vorzugsweise 0,1 mm, oder 0,2 mm, vorzugsweise 0,1 mm gleich ist.
EP90901699A 1989-01-03 1990-01-02 Filter zum abtrennen von teilchen aus gasen Expired - Lifetime EP0452387B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT90901699T ATE103209T1 (de) 1989-01-03 1990-01-02 Filter zum abtrennen von teilchen aus gasen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8900017A SE462615B (sv) 1989-01-03 1989-01-03 Filter foer rening av gaser
SE8900017 1989-01-03

Publications (2)

Publication Number Publication Date
EP0452387A1 EP0452387A1 (de) 1991-10-23
EP0452387B1 true EP0452387B1 (de) 1994-03-23

Family

ID=20374672

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90901699A Expired - Lifetime EP0452387B1 (de) 1989-01-03 1990-01-02 Filter zum abtrennen von teilchen aus gasen

Country Status (7)

Country Link
EP (1) EP0452387B1 (de)
JP (1) JPH04502577A (de)
AU (1) AU4836290A (de)
CA (1) CA2045146A1 (de)
DE (1) DE69007611D1 (de)
SE (1) SE462615B (de)
WO (1) WO1990007382A1 (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19542859A1 (de) * 1995-11-17 1997-05-22 Hosokawa Mikropul Ges Fuer Mah Oberflächenfiltration- und -filter
US5938818A (en) * 1997-08-22 1999-08-17 Energy & Environmental Research Center Foundation Advanced hybrid particulate collector and method of operation
US20040065201A1 (en) * 2001-02-23 2004-04-08 Walter Eckert Electrostatic dust separator with integrated filter tubing
US6544317B2 (en) 2001-03-21 2003-04-08 Energy & Environmental Research Center Foundation Advanced hybrid particulate collector and method of operation
KR100453930B1 (ko) * 2002-08-29 2004-10-20 한국에너지기술연구원 조합형 집진장치
KR101181546B1 (ko) * 2005-11-02 2012-09-10 엘지전자 주식회사 정전식모 섬유를 포함하는 공기정화기
US7990650B2 (en) * 2006-07-14 2011-08-02 Hitachi Global Storage Technologies, Netherlands B.V. Reducing the obstruction of air flow through a bypass channel associated with a disk drive using an electrostatic pass-by filter

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3018845A (en) * 1957-12-12 1962-01-30 Milton A Powers Filters
NL256788A (de) * 1958-09-12
US3910779A (en) * 1973-07-23 1975-10-07 Gaylord W Penney Electrostatic dust filter
EP0142547B1 (de) * 1983-05-10 1987-04-29 Industriell Arbetshygien I Söderhamn Ab Filtervorrichtung für luft- und gasreinigung

Also Published As

Publication number Publication date
JPH04502577A (ja) 1992-05-14
WO1990007382A1 (en) 1990-07-12
SE8900017D0 (sv) 1989-01-03
AU4836290A (en) 1990-08-01
CA2045146A1 (en) 1990-07-04
SE462615B (sv) 1990-07-30
EP0452387A1 (de) 1991-10-23
DE69007611D1 (de) 1994-04-28

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