CA2147210A1 - Method and apparatus for cleaning the filter medium in a suction dryer - Google Patents

Method and apparatus for cleaning the filter medium in a suction dryer

Info

Publication number
CA2147210A1
CA2147210A1 CA002147210A CA2147210A CA2147210A1 CA 2147210 A1 CA2147210 A1 CA 2147210A1 CA 002147210 A CA002147210 A CA 002147210A CA 2147210 A CA2147210 A CA 2147210A CA 2147210 A1 CA2147210 A1 CA 2147210A1
Authority
CA
Canada
Prior art keywords
filter
ultrasonic
filter medium
focusing
oscillating
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
Application number
CA002147210A
Other languages
French (fr)
Inventor
Bjarne Ekberg
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.)
Outotec Finland Oy
Original Assignee
Individual
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 Individual filed Critical Individual
Publication of CA2147210A1 publication Critical patent/CA2147210A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00Drying solid materials or objects by processes not involving the application of heat
    • F26B5/02Drying solid materials or objects by processes not involving the application of heat by using ultrasonic vibrations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D33/00Filters with filtering elements which move during the filtering operation
    • B01D33/15Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces
    • B01D33/21Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with hollow filtering discs transversely mounted on a hollow rotary shaft
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D33/00Filters with filtering elements which move during the filtering operation
    • B01D33/44Regenerating the filter material in the filter
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D33/00Filters with filtering elements which move during the filtering operation
    • B01D33/44Regenerating the filter material in the filter
    • B01D33/46Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element
    • B01D33/466Regenerating the filter material in the filter by scrapers, brushes nozzles or the like acting on the cake-side of the filtering element scrapers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D33/00Filters with filtering elements which move during the filtering operation
    • B01D33/44Regenerating the filter material in the filter
    • B01D33/52Regenerating the filter material in the filter by forces created by movement of the filter element
    • B01D33/54Regenerating the filter material in the filter by forces created by movement of the filter element involving vibrations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B3/00Cleaning by methods involving the use or presence of liquid or steam
    • B08B3/04Cleaning involving contact with liquid
    • B08B3/10Cleaning involving contact with liquid with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
    • B08B3/12Cleaning involving contact with liquid with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration by sonic or ultrasonic vibrations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2201/00Details relating to filtering apparatus
    • B01D2201/28Position of the filtering element
    • B01D2201/282Filtering elements with a horizontal rotation or symmetry axis

Abstract

(57) ABSTRACT

The invention relates to a method and apparatus for cleaning the filtermedium in a suction dryer by means of ultrasound in an essentially continuous operation. According to the invention, the ultrasonic beams emitted from at least one ultrasonic oscillator (1, 12, 22, 36) are focused essentially near to the filter surface (4, 14, 25) of the filter medium, advantageously on the filter surface (4, 14, 25) of the filter medium, in order to create at least one ultrasound focusing zone.

Description

2~721f~ `

METHOD AND APPARATUS FOR CLEANING THE FILTER MEDIUM IN A
SUCTION DRYER

The present invention relates to a method and apparatus for cleaning the filter 5 medium of a suction dryer by means of ultrasound in an essentially continuous operation.

The Fl patent 61,739 introduces a drying method and apparatus for drying web-like, pulverous, solid or porous material, in which method the material to 10 be dried is put, by intermediation of a fine porous liquid suction surface, into hydraulic contact with a liquid maintained at an underpressure in relation to the material to be dried. The apparatus used in the said method comprises a fine porous liquid suction surface, where the radii of the fine pores are mainly within the range 0.5 - 2 microrneters.

The fine porous liquid suction surface forms the filter surface for the filter medium of the suction dryer, which filter surface is set into contact with the material to be dried, such as slurry. When the filter surface is for instance plane-like, and when there is created underpressure at the surface opposite to 20 the fiiter surface of the filter medium, on the filter surface there is created, due to the suction, a cake filtered of the material to be dried, which cake is then scraped off the filter surface. However, the filter surface is susceptible to cho~
king, because the pore structure of the filter surface of the filter medium, andthus also that of the filter medium itself, is gradually filled with finely divided 25 material to be dried.

It is known in the prior art to use ultrasound in the cleaning of the filter surface of the filter medium of a suction dryer, as is described in the Fl patent 76,705.
In the method of this Fl patent 76,705, the use of ultrasound requires that for 30 the duration of ultrasonically boosted cleaning, the filter surface is set into contact with a connecting and cleaning liquid, such as water. In that case, when the filter surface is surrounded by water, the required ultrasound power . ., is not very high, and the risk for corrosion owing to the cavitation is eliminated.
However, the changing of the material surrounding the filter medium reduces the capacity available in the suction dryer, and thus increases the installationand running costs of the suction dryer.

From the Fl patent 82,388, there is known a cleaning method for the filter medium of a suction dryer, in which method the cleaning with an ultrasonic oscillator takes place essentially immediately after scraping the filter medium.In this method of the Fl patent 82,388, the ultrasonic oscillator is located in the 10 basin of the slurry to be filtered, underneath the liquid surface, in order to carry out the cleaning of the filter medium in continuous operation. ~Ith a high solidcontent of the surrounding slurry, the required ultrasonic power rises high, tooLikewise, the surrounding slurry corrodes the shell of the ultrasonic oscillatordue to intensive cavitation. An increase in the ultrasonic power and the 15 changing of the oscillator shells increase the running costs of the suction dryer.
.::

It is an object of the present invention to eliminate some of the drawbacks of the prior art and to achieve an improved cleaning method for the filter medium 20 of a suction dryer, in which method the filter medium is cleaned by means of ultrasound in an apparatus which focuses the ultrasonic sound field to be narrow. The essential novel features of the invention are enlisted in the appended patent claims.

25 According to the invention, the cleaning of the filter medium of a suction dryer is carried out by means of an ultrasonic device which focuses the ultrasonic sound field to be so narrow that the ultrasonic field advantageously falls on the filter surface of the filter medium for an essentially short time, which is 10 - 150 milliseconds, advantageously 60 - 90 milliseconds. Now the energy frequency 30 on the surface of the ultrasonic oscillator is low, and the ultrasonic oscillator can also be installed underneath the liquid surface of the slurry located in thebasin of the structure and surrounding the ultrasonic oscillator. Owing to the . . .

low energy frequency on the surface of the ultrasonic oscillator, also the danger of corrosion in the oscillator shell is low. However, on the filter surface of the filter medium, the ultrasonic power is high owing to the focusing according to the invention, and the cleaning is carried out effectively. The invention can advantageously be applied both to a filter medium composed of filter elements and to a uniform filter medium covering essentially the whole filter surface of the suction dryer.
:"
The focusing of ultrasound according to the invention to essentially near to the10 filter surface of the filter medium, advantageously on the filter surface of the filter medium, can be carried out by using one or several ultrasonic oscillators.
When employing one ultrasonic oscillator in the method of the invention, the -~
oscillating surface of the oscillator is essentially concave or convex. When theoscillating surface is concave, the oscillating surface itself advantageously 15 serves as a reflector by focusing the ultrasound on a narrow area on the filter surface of the filter medium. When the oscillating surface is convex, ultrasoundis conducted, via a concave reflector surface onto the filter surface of the filter medium.

20 When using at least two ultrasonic oscillators, the oscillators are advantageously arranged, with respect to each other, in a position where the beams coming from the ultrasonic oscillators intersect on the filter surface of the filter medium, or essentially near to the filter surface of the filter medium, so that the ultrasound emitted from the oscillators is focused on a small area 2~ on the filter surface of the filter medium. Now at least part of the ultrasonic oscillators have an advantageously planar oscillating surface. Furthermore, when using two or more ultrasonic oscillators, the oscillators can be installed at diflerent lengths from the filter surface of the filter medium.

30 According to the invention, the focusing of ultrasonic beams created by two or more ultrasonic oscillators to essentially near to the filter surface of the filter medium, advantageously on the filter surface of the filter medium, can also be carried out so that for one an~ the same filter medium, there are created two or more separate narrow ultrasound focusing zones by employing two or more ultrasonic oscillators. The size of the ultrasound focusing zones is within the -~
range 1 - 30 mm, advantageously 10-15 mm.

In the apparatus of the invention, in the vicinity of the filter surface of the filter medium, there are created, by means of at least one ultrasonic oscillator, an oscillating surface that focuses the ultrasonic beams onto the filter surface. The employed oscillating surface according to the invention can advantageously be convex or concave. The oscillating surface can also be composed of several essentially planar oscillating surfaces, which are advantageously installed tangentially with respect to the circumference of the same circle. When using a convex oscillating surface, the osciliator itself is advantageously rod-like in shape, but in this case the shape of the oscillator can also contain, in addition to a convex oscillating surface, planar elements on the same cross-sectional level.

The invention is described in further detail below, with reference to the appended drawings, wherein -.` :~
figure 1 is a schematic top-view illustration of a preferred embodiment of the - ;
invention, ` -figure 2 is a schematic top-view illustration of another preferred embodiment of ~ . ... ..
the invention, figure 3 is a schematic top-view illustration of a third preferred embodiment of -. -the invention, and figure 4 is a schematic cross-section of the location of the ultrasonic oscillator of the invention in a suction dryer.

According to figure 1, the oscillating surface 2 of the ultrasonic oscillator 1 is essentially concave in shape. With respect to the filter element 3 of the suction ;
dryer, the oscillating surface 2 is installed in a position where the beams '. '",'~; ~'';', 2147210 :

emitted from the oscillating surface 2 are directed to the filter surface 4 of the filter medium 3 so that the radiating effect of the beams is focused only on a limited area of the filter surface 4. According to figure 1, two separate ultrasound focusing zones are created on the filter surface 4.
In figure 2, in the ultrasonic cleaning of the filter medium 11 of a suction dryer there is used an ultrasonic oscillator 12, the oscillating surface 13 whereof isessentially convex in shape and which oscillator is located on the opposite sidewith respect to the filter element 11. In order to conduct ultrasonic beams onto10 the filter surface 14 of the filter medium 11, there is installed an essentially concave reflector surface 15 in the vicinity of the ultrasonic oscillator 12, but on the opposite side with respect to the filter element 11. The ultrasonic beams emitted from the oscillating surface 13 are reflected from the reflector surface15 so that the ultrasonic beams are focused on an essentially narrow area of 15 the filter surface 14 of the filter medium.

In figure 3, in the vicinity of the filter medium 21 a the suction dryer, there are installed ultrasonic oscillators 22 so that the oscillating surfaces 23 of the ultrasonic oscillators at least tangentially touch the circumference 24 of one 20 and the same circle. Even in shape, the oscillating surface 23 can be essentially similar to the circumference 24 of a circle. Now the ultrasonic beams emitted from the ultrasonic oscillators 22 advantageously intersect on the filter surface 25 of the filter medium 21, or essentially in the immediate vicinity of the filter surface 25. Thus the ultrasonic power coming from the 25 ultrasonic oscillators 22 can be focused on an essentially small area.

According to figure 4, the suction dryer 31 comprises a slurry tank 32, a disc 34 rotatable around the axis 33, to which disc the filter elements 35 of the filter medium are attached, and a scraper 36 for removing the filter cake formed on 30 the filter surface 37 of the filter element. The ultrasonic oscillator or oscillators 3~ for focusing the ultrasonic beams to the filter element 35 are according to the invention located underneath the slurry surface 39.

.
.

Claims (10)

1. A method for cleaning the filter medium of a suction dryer in an essentially continuous operation by means of ultrasound, characterized in that the ultrasonic beams emitted from at least one ultrasonic oscillator (1, 12, 22, 36)are focused essentially near to the filter surface (4, 14, 25) of the filter medium, advantageously on the filter surface (4, 14, 25) of the filter medium, in order to form at least one ultrasound focusing zone.
2. A method according to claim 1, characterized in that the focusing of ultrasonic beams onto the filter surface (14) of the filter medium is carried out by means of a concave oscillating surface (2) formed in the ultrasonic oscillator (1).
3. A method according to claim 1, characterized in that the focusing of ultrasonic beams onto the filter surface (14) of the filter medium is carried out by means of a concave reflector surface (15) provided separately from the ultrasonic oscillator (12).
4. A method according to claim 3, characterized in that the focusing of ultrasonic beams onto the filter surface (14) of the filter medium is carried out by means of a convex oscillating surface (13) formed in the ultrasonic oscillator (12) and by means of a concave reflector surface (15) provided separately from the ultrasonic oscillator (12).
5. A method according to claim 1, characterized in that the focusing of ultrasonic beams onto the filter surface (14) of the filter medium is carried out by means of ultrasonic oscillators (22) located on different distances fro the filter surface (14).
6. A method according to claim 1, characterized in that the focusing of ultrasonic beams onto the filter surface (14) of the filter medium is carried out by means of ultrasonic oscillators (22) located essentially tangentially on the circumference (24) of the same circle as for their oscillating surfaces.
7. An apparatus for realizing the method of claim 1, characterized in that in the vicinity of the filter surface (4, 14, 25) of the filter medium, there is formed , by means of at least one ultrasonic oscillator (1, 12, 22, 36), a surface (2, 15, 23) which focuses the ultrasonic beams onto the filter surface (4, 14, 25).
8. An apparatus according to claim 7, characterized in that the focusing surface (2) is a concave oscillating surface of an ultrasonic oscillator.
9. An apparatus according to claim 7, characterized in that the focusing surface (15) is a concave reflector surface.
10. An apparatus according to claim 7, characterized in that the focusing oscillating surface comprises several oscillating surfaces (23) which are at least tangentially located on the circumference (24) of one and the same circle.
CA002147210A 1994-04-19 1995-04-18 Method and apparatus for cleaning the filter medium in a suction dryer Abandoned CA2147210A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI941796A FI95781C (en) 1994-04-19 1994-04-19 Method and apparatus for cleaning the filter medium in a suction dryer
FI941796 1994-04-19

Publications (1)

Publication Number Publication Date
CA2147210A1 true CA2147210A1 (en) 1995-10-20

Family

ID=8540547

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002147210A Abandoned CA2147210A1 (en) 1994-04-19 1995-04-18 Method and apparatus for cleaning the filter medium in a suction dryer

Country Status (11)

Country Link
US (1) US5653816A (en)
EP (1) EP0682970B1 (en)
JP (1) JPH0847607A (en)
KR (1) KR100338863B1 (en)
AT (1) ATE169512T1 (en)
AU (1) AU683988B2 (en)
BR (1) BR9501730A (en)
CA (1) CA2147210A1 (en)
DE (1) DE69503964T2 (en)
FI (1) FI95781C (en)
RU (1) RU2142318C1 (en)

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FI104412B (en) 1996-10-17 2000-01-31 Outokumpu Oy Method and apparatus for cleaning a filter surface
US6221255B1 (en) 1998-01-26 2001-04-24 Achyut R. Vadoothker Ultrasound-assisted filtration system
US6948843B2 (en) * 1998-10-28 2005-09-27 Covaris, Inc. Method and apparatus for acoustically controlling liquid solutions in microfluidic devices
US7687039B2 (en) * 1998-10-28 2010-03-30 Covaris, Inc. Methods and systems for modulating acoustic energy delivery
US6311702B1 (en) * 1998-11-11 2001-11-06 Applied Materials, Inc. Megasonic cleaner
DE10058281C2 (en) * 2000-11-24 2002-10-31 Ingo Stark Process for the quality production of flocked workpieces with a solid basic structure
US6843914B2 (en) * 2001-12-13 2005-01-18 Julius James Jablonsky Filtration apparatus and process
FI118253B (en) * 2003-10-13 2007-09-14 Larox Oyj Method and apparatus for cleaning the filter plate
US7694376B2 (en) * 2005-09-09 2010-04-13 Chunghwa Picture Tubes, Ltd. Cleansing module for fluid-supply apparatus
EP1925359A1 (en) 2006-11-22 2008-05-28 Covaris, Inc. Methods and apparatus for treating samples with acoustic energy to form particles and particulates
DE102008031287B4 (en) * 2008-07-02 2016-07-28 Schaeffler Technologies AG & Co. KG Sealing device for a machine element, in particular for a rolling or sliding bearing
CN103203338A (en) * 2013-03-18 2013-07-17 无锡南方声学工程有限公司 Ultrasound cleaning device of filter element in polyester industry
US11000791B2 (en) * 2019-03-06 2021-05-11 Veolia Water Solutions & Technologies Support Rotary disc filter having backwash guides

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US4260928A (en) * 1978-11-09 1981-04-07 General Electric Company Electro-acoustic transducer with horn and reflector
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Also Published As

Publication number Publication date
US5653816A (en) 1997-08-05
FI941796A0 (en) 1994-04-19
FI941796A (en) 1995-10-20
KR950033384A (en) 1995-12-26
FI95781C (en) 1996-03-25
RU95105894A (en) 1996-12-27
RU2142318C1 (en) 1999-12-10
DE69503964T2 (en) 1999-03-11
BR9501730A (en) 1995-11-14
EP0682970A2 (en) 1995-11-22
EP0682970B1 (en) 1998-08-12
JPH0847607A (en) 1996-02-20
FI95781B (en) 1995-12-15
KR100338863B1 (en) 2002-10-31
AU1647695A (en) 1995-10-26
AU683988B2 (en) 1997-11-27
ATE169512T1 (en) 1998-08-15
EP0682970A3 (en) 1996-07-17
DE69503964D1 (en) 1998-09-17

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Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued