CA2045146A1 - Filter for separating particles from gases - Google Patents
Filter for separating particles from gasesInfo
- Publication number
- CA2045146A1 CA2045146A1 CA002045146A CA2045146A CA2045146A1 CA 2045146 A1 CA2045146 A1 CA 2045146A1 CA 002045146 A CA002045146 A CA 002045146A CA 2045146 A CA2045146 A CA 2045146A CA 2045146 A1 CA2045146 A1 CA 2045146A1
- Authority
- CA
- Canada
- Prior art keywords
- filter
- gases
- members
- electrodes
- 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.)
- Abandoned
Links
- 239000007789 gas Substances 0.000 title claims abstract description 35
- 239000002245 particle Substances 0.000 title claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 19
- 238000007599 discharging Methods 0.000 claims abstract description 3
- 238000012216 screening Methods 0.000 claims abstract description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 4
- 239000004753 textile Substances 0.000 claims description 3
- 239000000428 dust Substances 0.000 description 28
- 238000004140 cleaning Methods 0.000 description 9
- 239000012535 impurity Substances 0.000 description 7
- 241000196324 Embryophyta Species 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 239000004809 Teflon Substances 0.000 description 3
- 229920006362 Teflon® Polymers 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical compound FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 229940036051 sojourn Drugs 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- BHMLFPOTZYRDKA-IRXDYDNUSA-N (2s)-2-[(s)-(2-iodophenoxy)-phenylmethyl]morpholine Chemical compound IC1=CC=CC=C1O[C@@H](C=1C=CC=CC=1)[C@H]1OCCNC1 BHMLFPOTZYRDKA-IRXDYDNUSA-N 0.000 description 1
- -1 Acryl Chemical group 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229920013632 Ryton Polymers 0.000 description 1
- 239000004736 Ryton® Substances 0.000 description 1
- 240000006064 Urena lobata Species 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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
Landscapes
- Filtering Of Dispersed Particles In Gases (AREA)
- Electrostatic Separation (AREA)
Abstract
A filter (1) for separating particles from gases by screening, said filter comprising bag-shaped filter material (7) made of filter material, each filter member having at least one opening for discharging the gases flowing through the filter material of said filter member. Furthermore, the filter (1) has pervious stiffening means arranged inside said filter members. The outsides of the filter members (7) are provided with fibres (13) hanging loosely from the filter material, electrically conductive means (8) being arranged inside and/or outside the filter members for charging said fibres.
Description
W~ n/(~ C~ .q t~
FILTER FOR SEPARATING PARTICLES FROM GASES
The present invention relates to a filter for separating particles from gases by screening, comprising bag-shaped filter members made of filter material, each filter member having at least one opening for discharging the gases flowing through the filter medium of said filter member, and pervious stiffening means arranged inside said filter members.
When such filters are used for cleaning dust-laden gases, for example flue ~ases 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.
In flue gas cleaning plants where the filter is disposed downstream of a contact reactor, for separating the gaseous impurities, such as sulphur oxide compounds and hydrogen chloride etc., by supplying an absorbent reacting with these impurities, also reaction products and unreacted absorbent will be deposited in the dust cakes of the filter members. Consequently, the gaseous impurities not separated in the contact reactor can be separated in the filter, and ~he degree of separation is naturally due to.the sojourn time of the gases in the dust cakes.-The thicker the dust cakes, the.longer the sojourn time, and the higher the degree of separation.
~ .Asithe thickness of .the dust.cakes increases, the pressure drop - across the filter increases as we!l. Since the energy consumption by the - fans of the plant increases, and since the fans are not capable of pressing the gases through the filter at very hi~h pressure dropsj the cake thickness wi.ll thus be~limited by the pressure drop which in turn is 30 determined by the magnitude of the resistance which the.dust cakes exert .-~ on-the gas.flow.~
!i.,: :, When the f;lter-is.used.in a.plant for cleaning flue gases from a - refuse incineration plant,~it..is especially difficul~ to maintain thick dust~cakes on the filter members,-since gaseous:hydro~en chloride and,`if the refuse is humid, considerable amounts of:.water.:vapour are formed. If 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 stickyO As a result, the resistance and, consequently, the pressure drop across the dust cakes will be considerable so that the thickness of the dust cakes ~, at the maximum pressure drop allowed will not be sufficient for producing a satisfactory separat;on of the particulate and gaseous impurities of the flue gases, and the filter will be difficult to clean.
To improve the degree of separation for such filters, efforts have been made to lower the filter operating temperature to a level at which the gaseous impurities are precipitated as drops in the filter. These drops are naturally taken up more easily by the filter than are the gaseous impurities. Thus, a higher degree of separation is obtained.
Unfortunately, the dust cakes become humid and sticky, and conse-quently difficult to remove from the filter members. Furthermore, the filter operating temperature is in this case at a level too low for the remaining process. ~'' If 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. However, 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 ox'ide 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 applica-tions, i.e. also in a plant for cleaning flue gases from a refuse in-cineration-plant.~ ?~ ' ' 3 ~ 3;~
This object is achieved according to the invention by'~ filter of ; the type~described by`way of`introduction and characterised in that the outsides of the filter-members are provided w;th fibres hanging lbosely 35 -from the f;lter,~and that'electrically'conductivè means are arranged inside and/or~outside the filter members,for charging sàid fibres.
i Preferably, the!electrically'-conductive-means inside ~he filter members consist of the said stiffening means, while'the electrically -, :
:
wn ~n/n7~?
~ ~ A ~ F~Jnn~n~
J _ .
conductive mcans outside the filter members consist of electrodes.
' It is preferred that a voltage of 0-50 kV, especially 20 kV, nas 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.
It is preferred that the filter medium consists of textile material which, 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.
The invention will be described in more detail hereinbelow, with re-ference to the accompanying drawing.
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-SOO,'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); Thé 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 a`djacent filter bags 7 is 30D-500 mm,-;usually 400 mm. The transverse spacing~is 300-500 mm, usually 400 mm.' ~
,;o~ ,- Electrodes 8 are arranged between`the'`filtèr;b.ags such~that"one electrode is pO5i tioned at each point of intersèctionibetween'ltheidiagonal lines of,four~longitudinally and transYersely~adjacent f;lter bags.
~As is apparent from F;g.!1, the electrodes have the same lèn`gth,''`but are thinner than the filter bags and ;n the form of round rods. Their diameter is 20-40 mm, usually 30 mm. The electrodes are inserted through , - . - ' ` , `~'Ui YGiû733~
~J~ti~]~JoU.7 holes ~not shown) in the plate 5 and are kept in place by means of hol-ders (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 fi~ter bags 7, such that one nozzle is positioned over the upper open end of each filter bag. Consequently, each filter bag, when being cleaned, re-ceives 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 com-pressed air. The nozzle tubes are detachably mounted in the clean gas cham-ber 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.
As is also apparent from Fig. 1, the bottom of the filter housing 2 is fuqnel-shaped to serve as a dust pocket for collecting the ~ust separated from the raw gas. The dust is then fed to a dust cont~iner (not shown) by means of a screw conveyor (not shown).
-As is apparent from Fig. 2, the filter 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, thése cages are earthed via the plate 5.
- 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 filterO 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 60-130C polyester for temperatures of,130-15Q~C RYTON for temperatures of 150-180C, and TEFLON
,forjitemperatures of-180-240C.~n ~ - ? ) ~ ; " J -' ~ ,5 The length of the fibres ,is 10~50 mm, preferably 30 mm, and the - i~35 ;thickness is smaller than or equalling 0.2 mm, preferably 0.1 mm.
`~ ~
.
qn/n7~.~?
rd ' ~
r The bag filter operates as fo110ws. The dust-laden gases to be cleaned in the bag filter are conducted, under a certain excess pressure, into the raw gas chamber 2b of 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-act with the gravity. Consequently, the dust released by the cleaning of the filter bags 7 will not be re-cycled to the bags by the incoming gases.
Since a voltage of 20 kV has been applied to the electrodes, and the filter bags have been earthed, eiectric fields will form inside the raw gas chamber and charge the fibres 13 of the filter bags which will stand out from the outsides of the filter bags in the direction of the field lines (see Fig. 2).
When the gases pass through these fields, their dust particles will be charged with a charge opposite to the charge of the fibres. Thus, the particles will be attracted to the fibres 13 when the gases flow through the filter bags 7 and the cages 12 towards the inside of the filter bags.
When the particles come into contact with the charged fibres, they will be neutralised and no longer repel each other, but instead agglomerate on the outsides of the filter bags. Since comparatively large particles will accumulate on the outsides of the filter bags, the resulting dust cakes 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 bag filter accor~ing to the invention has the same pressure drop as a conventional bag filter, although it has ~ar thicker dust cakes than the conventional filter. The present bag filter thus ob-tains a higher degree of separation than a conventional bag fil$er at the same pressure drop.
Then, 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 d;scharged ;nto the atmosphere (see F;g. 1).
The fibres hanging loosely on the outsides of the f;lter 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 a N0x-catalyst, will remain on the filter bags.
-w~ Qn/n7~
~ Y-~iUU~U2 . ,, : ..
r~
Naturally, the invention is not restricted to the embodiment de-scribed above, and it can be modified in several different ways with-in the scope of the accompanying claims.
Instead of applying a voltage of 20 kV to the electrodes and ,.
earthing the cages, one may natura11y do it the other way round, i.e.
earth the electrodes and apply a voltage of 20 kV to the cages.
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.
It would, for example, be possible to replace the electrodes arranged between the filter bags by cylindrical; gas-pervious electrodes round each filter bag.
The round rod electrodes may, of course, also be of square or spiral form.
~ .
., . ! i , . ' ^ - . , ? ~ ? i ii ,
FILTER FOR SEPARATING PARTICLES FROM GASES
The present invention relates to a filter for separating particles from gases by screening, comprising bag-shaped filter members made of filter material, each filter member having at least one opening for discharging the gases flowing through the filter medium of said filter member, and pervious stiffening means arranged inside said filter members.
When such filters are used for cleaning dust-laden gases, for example flue ~ases 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.
In flue gas cleaning plants where the filter is disposed downstream of a contact reactor, for separating the gaseous impurities, such as sulphur oxide compounds and hydrogen chloride etc., by supplying an absorbent reacting with these impurities, also reaction products and unreacted absorbent will be deposited in the dust cakes of the filter members. Consequently, the gaseous impurities not separated in the contact reactor can be separated in the filter, and ~he degree of separation is naturally due to.the sojourn time of the gases in the dust cakes.-The thicker the dust cakes, the.longer the sojourn time, and the higher the degree of separation.
~ .Asithe thickness of .the dust.cakes increases, the pressure drop - across the filter increases as we!l. Since the energy consumption by the - fans of the plant increases, and since the fans are not capable of pressing the gases through the filter at very hi~h pressure dropsj the cake thickness wi.ll thus be~limited by the pressure drop which in turn is 30 determined by the magnitude of the resistance which the.dust cakes exert .-~ on-the gas.flow.~
!i.,: :, When the f;lter-is.used.in a.plant for cleaning flue gases from a - refuse incineration plant,~it..is especially difficul~ to maintain thick dust~cakes on the filter members,-since gaseous:hydro~en chloride and,`if the refuse is humid, considerable amounts of:.water.:vapour are formed. If 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 stickyO As a result, the resistance and, consequently, the pressure drop across the dust cakes will be considerable so that the thickness of the dust cakes ~, at the maximum pressure drop allowed will not be sufficient for producing a satisfactory separat;on of the particulate and gaseous impurities of the flue gases, and the filter will be difficult to clean.
To improve the degree of separation for such filters, efforts have been made to lower the filter operating temperature to a level at which the gaseous impurities are precipitated as drops in the filter. These drops are naturally taken up more easily by the filter than are the gaseous impurities. Thus, a higher degree of separation is obtained.
Unfortunately, the dust cakes become humid and sticky, and conse-quently difficult to remove from the filter members. Furthermore, the filter operating temperature is in this case at a level too low for the remaining process. ~'' If 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. However, 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 ox'ide 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 applica-tions, i.e. also in a plant for cleaning flue gases from a refuse in-cineration-plant.~ ?~ ' ' 3 ~ 3;~
This object is achieved according to the invention by'~ filter of ; the type~described by`way of`introduction and characterised in that the outsides of the filter-members are provided w;th fibres hanging lbosely 35 -from the f;lter,~and that'electrically'conductivè means are arranged inside and/or~outside the filter members,for charging sàid fibres.
i Preferably, the!electrically'-conductive-means inside ~he filter members consist of the said stiffening means, while'the electrically -, :
:
wn ~n/n7~?
~ ~ A ~ F~Jnn~n~
J _ .
conductive mcans outside the filter members consist of electrodes.
' It is preferred that a voltage of 0-50 kV, especially 20 kV, nas 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.
It is preferred that the filter medium consists of textile material which, 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.
The invention will be described in more detail hereinbelow, with re-ference to the accompanying drawing.
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-SOO,'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); Thé 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 a`djacent filter bags 7 is 30D-500 mm,-;usually 400 mm. The transverse spacing~is 300-500 mm, usually 400 mm.' ~
,;o~ ,- Electrodes 8 are arranged between`the'`filtèr;b.ags such~that"one electrode is pO5i tioned at each point of intersèctionibetween'ltheidiagonal lines of,four~longitudinally and transYersely~adjacent f;lter bags.
~As is apparent from F;g.!1, the electrodes have the same lèn`gth,''`but are thinner than the filter bags and ;n the form of round rods. Their diameter is 20-40 mm, usually 30 mm. The electrodes are inserted through , - . - ' ` , `~'Ui YGiû733~
~J~ti~]~JoU.7 holes ~not shown) in the plate 5 and are kept in place by means of hol-ders (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 fi~ter bags 7, such that one nozzle is positioned over the upper open end of each filter bag. Consequently, each filter bag, when being cleaned, re-ceives 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 com-pressed air. The nozzle tubes are detachably mounted in the clean gas cham-ber 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.
As is also apparent from Fig. 1, the bottom of the filter housing 2 is fuqnel-shaped to serve as a dust pocket for collecting the ~ust separated from the raw gas. The dust is then fed to a dust cont~iner (not shown) by means of a screw conveyor (not shown).
-As is apparent from Fig. 2, the filter 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, thése cages are earthed via the plate 5.
- 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 filterO 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 60-130C polyester for temperatures of,130-15Q~C RYTON for temperatures of 150-180C, and TEFLON
,forjitemperatures of-180-240C.~n ~ - ? ) ~ ; " J -' ~ ,5 The length of the fibres ,is 10~50 mm, preferably 30 mm, and the - i~35 ;thickness is smaller than or equalling 0.2 mm, preferably 0.1 mm.
`~ ~
.
qn/n7~.~?
rd ' ~
r The bag filter operates as fo110ws. The dust-laden gases to be cleaned in the bag filter are conducted, under a certain excess pressure, into the raw gas chamber 2b of 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-act with the gravity. Consequently, the dust released by the cleaning of the filter bags 7 will not be re-cycled to the bags by the incoming gases.
Since a voltage of 20 kV has been applied to the electrodes, and the filter bags have been earthed, eiectric fields will form inside the raw gas chamber and charge the fibres 13 of the filter bags which will stand out from the outsides of the filter bags in the direction of the field lines (see Fig. 2).
When the gases pass through these fields, their dust particles will be charged with a charge opposite to the charge of the fibres. Thus, the particles will be attracted to the fibres 13 when the gases flow through the filter bags 7 and the cages 12 towards the inside of the filter bags.
When the particles come into contact with the charged fibres, they will be neutralised and no longer repel each other, but instead agglomerate on the outsides of the filter bags. Since comparatively large particles will accumulate on the outsides of the filter bags, the resulting dust cakes 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 bag filter accor~ing to the invention has the same pressure drop as a conventional bag filter, although it has ~ar thicker dust cakes than the conventional filter. The present bag filter thus ob-tains a higher degree of separation than a conventional bag fil$er at the same pressure drop.
Then, 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 d;scharged ;nto the atmosphere (see F;g. 1).
The fibres hanging loosely on the outsides of the f;lter 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 a N0x-catalyst, will remain on the filter bags.
-w~ Qn/n7~
~ Y-~iUU~U2 . ,, : ..
r~
Naturally, the invention is not restricted to the embodiment de-scribed above, and it can be modified in several different ways with-in the scope of the accompanying claims.
Instead of applying a voltage of 20 kV to the electrodes and ,.
earthing the cages, one may natura11y do it the other way round, i.e.
earth the electrodes and apply a voltage of 20 kV to the cages.
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.
It would, for example, be possible to replace the electrodes arranged between the filter bags by cylindrical; gas-pervious electrodes round each filter bag.
The round rod electrodes may, of course, also be of square or spiral form.
~ .
., . ! i , . ' ^ - . , ? ~ ? i ii ,
Claims (9)
1. A filter for separating particles from gases by screening, compris-ing bag-shaped filter members (7) made of filter medium, each filter member having at least one opening for discharging the gases flowing through the filter material of said filter member, and pervious stiffen-ing means (12) arranged inside said filter members, c h a r a c t e r -i s e d in that the outsides of the filter members (7) are provided with fibres (13) hanging loosely from the filter material, and that electrically conductive means (12, 8) are arranged inside and/or outside the filter members for charging said fibres .
2. A filter as claimed in claim 1, c h a r a c t e r i s e d in that the electrically conductive means arranged inside the filter members (7) consist of said stiffening means (12).
3. A filter as claimed in claim 1 or 2, c h a r a c t e r i s e d in that the electrically conductive means arranged outside the filter members (7) consists of electrodes (8).
4. A filter as claimed in claims 2 and 3, c h a r a c t e r i s e d in that a voltage of 0-50 kV, preferably 20 kV, has been applied between the stiffening means (12) and the electrodes (8).
5. A filter as claimed in claim 4, c h a r a c t e r i s e d in that the stiffening means (12) are earthed, and that a voltage of 0-50 kV, preferably 20 kV, has been applied to the electrodes (8).
6. A filter as claimed in claim 4, c h a r a c t e r i s e d in that the electrodes (8) are earthed, and that a voltage of 0-50 kV, preferably 20 kV, has been applied to the stiffening means (12).
7. A filter as claimed in any one of the preceding claims, c h a r a c -t e r i s e d in that the filter material consists of textile.
8. A filter as claimed in claim 7, c h a r a c t e r i s e d in that the filter material consists of PTFE (TEFLON).
9. A filter as claimed in any one of the preceding claims, c h a r a c -t e r i s e d in that the fibres (13) hanging loosely from the filter con-sist of PTFE (TEFLON) and have a length of 10-50 mm, preferably 30 mm, and a thickness smaller than or equalling 0.2 mm, preferably 0.1 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8900017-8 | 1989-01-03 | ||
| SE8900017A SE462615B (en) | 1989-01-03 | 1989-01-03 | FILTER FOR GAS CLEANING |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2045146A1 true CA2045146A1 (en) | 1990-07-04 |
Family
ID=20374672
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002045146A Abandoned CA2045146A1 (en) | 1989-01-03 | 1990-01-02 | Filter for separating particles from gases |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0452387B1 (en) |
| JP (1) | JPH04502577A (en) |
| AU (1) | AU4836290A (en) |
| CA (1) | CA2045146A1 (en) |
| DE (1) | DE69007611D1 (en) |
| SE (1) | SE462615B (en) |
| WO (1) | WO1990007382A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19542859A1 (en) * | 1995-11-17 | 1997-05-22 | Hosokawa Mikropul Ges Fuer Mah | Surface filtration and 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 (en) * | 2002-08-29 | 2004-10-20 | 한국에너지기술연구원 | Hybrid type dust collector |
| KR101181546B1 (en) * | 2005-11-02 | 2012-09-10 | 엘지전자 주식회사 | Air cleaner with electrostatic flocked pile |
| 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)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3018845A (en) * | 1957-12-12 | 1962-01-30 | Milton A Powers | Filters |
| NL256788A (en) * | 1958-09-12 | |||
| US3910779A (en) * | 1973-07-23 | 1975-10-07 | Gaylord W Penney | Electrostatic dust filter |
| US4610702A (en) * | 1983-05-10 | 1986-09-09 | Industriell Arbetshygien I Soderhamn Ab | Filter apparatus for air or gas purification |
-
1989
- 1989-01-03 SE SE8900017A patent/SE462615B/en not_active IP Right Cessation
-
1990
- 1990-01-02 EP EP90901699A patent/EP0452387B1/en not_active Expired - Lifetime
- 1990-01-02 JP JP2501820A patent/JPH04502577A/en active Pending
- 1990-01-02 DE DE90901699T patent/DE69007611D1/en not_active Expired - Lifetime
- 1990-01-02 WO PCT/SE1990/000002 patent/WO1990007382A1/en active IP Right Grant
- 1990-01-02 AU AU48362/90A patent/AU4836290A/en not_active Abandoned
- 1990-01-02 CA CA002045146A patent/CA2045146A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990007382A1 (en) | 1990-07-12 |
| DE69007611D1 (en) | 1994-04-28 |
| AU4836290A (en) | 1990-08-01 |
| SE462615B (en) | 1990-07-30 |
| SE8900017D0 (en) | 1989-01-03 |
| EP0452387A1 (en) | 1991-10-23 |
| EP0452387B1 (en) | 1994-03-23 |
| JPH04502577A (en) | 1992-05-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |