DE9103149U1 - Nozzle backwash filter - Google Patents

Description

Nozzle backwash filter

The invention relates to a nozzle backwash filter according to the preamble of patent claim 1.

Known nozzle backwash filters have a largely cylindrical filter insert arranged concentrically in a cylindrical filter housing, through which the liquid to be filtered flows from the inside to the outside. In the process, impurities are deposited on the inside of the filter insert. These impurities are removed from the filter using a concentrically mounted, rotating nozzle that has a closable drain line to the outside. An interval control

Patent Attorneys ■ European Patent Attorneys ■ Authorized Representatives before the European Patent Office

Attorney: admitted to the Hamburg courts

Deutsche Bank AG Hamburg, No. 05/28497 (bank code 200 700 00) ■ Postgiro Hamburg 28 42-206
Dresdner Ban;k AG Hamburg, No. 933 60 35 (bank code 200 800 00)

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or a differential pressure switch triggers the cleaning of the filter insert. The nozzle is rotated and the drain line is opened at the same time. The flushing head with the flushing gap is guided along the inner wall of the filter insert. The internal pressure in the filter creates a flow of liquid from the filtrate side through the filter insert into the flushing gap and from there through the opened drain line to the outside.

This liquid flow tears the contaminants out of the filter insert and flushes them out, e.g. into a sludge container. The filter medium in the filter insert is primarily metal mesh or, in the case of very fine filtration, multi-layer sintered fabric. However, textile fabrics, sintered metals or porous plastics can also be used as filter media.

Such nozzle backwash filters are known, for example, from DE-PS 34 43 752 and from DE-PS 34 31 396.

In the case of contamination with a strong adhesive force to the filter medium or in the case of very fine-meshed filter media, e.g. mesh size of less than 2OyULm, the force of the liquid flow in the known nozzle backwash filters is often not sufficient to safely remove the dirt from the filter medium.

Then it is necessary to open the filter, remove the filter insert and clean it mechanically or chemically/mechanically.

It is also known to use ultrasound to clean objects. Ultrasonic cleaning systems usually consist of a tank with a cleaning liquid, ultrasonic emitters or ultrasonic vibration elements and a high-frequency generator. Known high-frequency converters emit concentrated radiation into the cleaning liquid.

Cleaning devices for filters have a concentric structure with a centrally arranged ultrasonic cleaning tool, which is located in the immediate vicinity of the filter to be cleaned. Such devices are described in DE-PS 34 25 552, DE-OS 38 10 137 and DE-OS 36 27 932.

The disadvantage of these known devices is that the filter inserts to be cleaned must be removed from the filter and reinserted into the filter after cleaning in an external ultrasonic cleaning system.

The invention is therefore based on the object of providing a nozzle

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To create a backwash filter in which the solids or contaminants are removed from the filter medium without any problems, even in the case of strongly adhering contamination and/or very fine fabrics, so that the contaminants are removed with the backwash flow, thus avoiding periodic removal and external cleaning of the filter insert.

This problem is solved by the features of the characterizing part of claim I.

In the nozzle backwash filter according to the invention, ultrasonic oscillator elements are provided in the filter, which are excited by an ultrasonic generator. The ultrasonic oscillator elements are arranged adjacent to the filter insert, which has a filter medium, so that when the ultrasonic oscillator elements are excited during the backwash process, a high ultrasonic power density is generated directly on the filter medium, which loosens the adhering solids and thus makes them backwashable for the liquid flowing to the backwash nozzle. The ultrasonic oscillator elements can be attached in or to the filter housing. The gap between the filter housing and the filter medium is kept as small as possible.

The arrangement of ultrasonic oscillating elements in the filter and the ultrasonic power density generated thereby means that even strongly adhering contaminants are removed from the filter medium. Furthermore, very fine-meshed filter media are also safely cleaned, so that external cleaning of the filter insert is not necessary, unlike with known jet backwash filters. In addition to cost savings by avoiding the need to remove and install the filter insert, a significant advantage is that a longer interruption in operation is safely avoided with the jet backwash filter according to the invention.

According to one embodiment of the invention, the backwash nozzle is rotatable around the axis of the filter insert and is arranged inside the filter insert. The liquid to be filtered flows from an inlet area inside the filter insert through the filter insert to the outside and into an outlet area. The solids or contaminants are deposited on the inside of the filter insert. The ultrasonic oscillator elements are arranged in the wall of the filter housing and concentrically surround the filter insert. The gap between the concentrically arranged filter insert and the concentrically arranged ultrasonic oscillator elements is kept as small as possible.

but still just large enough to ensure proper drainage of the filtrate. Due to the small and uniform distance between the ultrasonic oscillator elements and the filter insert, a high and uniform ultrasonic power density is generated on the filter medium to be cleaned during the backwash process.

It can also be provided that the backwash nozzle is fixed in the filter housing and the filter insert is arranged so that it can rotate around the backwash nozzle. The relative movement between the nozzle and the filter insert remains the same as in the previously described embodiment. Thus, the backwash intensity also remains the same. The ultrasonic oscillator elements can be arranged in a row parallel to the longitudinal axis of the filter insert. During cleaning, the filter medium is then moved through a zone of high ultrasonic power density, so that every part of the fabric is exposed to high ultrasonic energy.

The row of ultrasonic vibrating elements can be arranged opposite the backwash nozzle to ensure that the solids are removed through the backwash nozzle immediately after they have been detached from the filter medium.

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Depending on the physical properties of the media to be filtered, the inertia of the removal of the solids detached by ultrasound can be taken into account by arranging the row of ultrasonic oscillating elements and thus the zone of high ultrasonic power density with respect to the direction of rotation of the filter insert at a certain distance in front of the backwash nozzle.

In order to be able to adjust the nozzle backwash filter according to the invention to different types of liquids, the row of ultrasonic oscillating elements is installed permanently in the housing wall, but the backwash nozzle is detachably attached to the filter housing so that it can be adjusted at a certain angle to the ultrasonic oscillating elements.

Depending on the type of filter medium, the distance between the ultrasonic oscillator elements and the filter medium is important. This can be taken into account by installing the ultrasonic oscillator elements in a strip that is arranged in the housing wall of the filter so that it can be moved radially.

In the case of particularly stubborn solids adhering to the filter medium,

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materials, the ultrasonic intensity can be increased by arranging two or more rows of ultrasonic oscillating elements one behind the other in the housing wall.

The ultrasonic power density can also be increased by installing two or more rows of ultrasonic oscillating elements in the filter housing so that their axes of action overlap in the filter medium to be cleaned. This arrangement can be made so that the axes of action overlap immediately in front of the backwash nozzle or at a certain distance from the backwash nozzle in relation to the direction of rotation of the filter insert.

According to a further embodiment of the invention, the backwash nozzle is arranged between the filter insert and the filter housing. A stationary or a rotating nozzle can be provided. This arrangement of the backwash nozzle is advantageous when the liquid to be filtered flows through the filter insert from the outside to the inside. The contaminants are deposited on the outside of the filter insert. If a stationary backwash nozzle is used in this embodiment of the invention, the filter insert is mounted so that it can rotate. The flushing gap of the backwash nozzle

As with the previously described embodiments of the invention, the nozzle is also arranged in the immediate vicinity of the filter insert. The backwash nozzle has a closable drain line to the outside via the filter housing. When cleaning, the rotating filter insert is guided along the fixed nozzle head. When the drain line is open, a strong flow of liquid is created from the filtrate side (inside) through the insert into the nozzle and from there through the open drain line to the outside. Ultrasonic oscillator elements can be arranged concentrically in the housing wall or in one or more rows parallel to the longitudinal axis of the filter insert. Furthermore, according to a further embodiment of the invention, the ultrasonic oscillator elements can be arranged within the filter insert in the immediate vicinity of the filter medium.

In order to maintain the operating pressure required for the filtrate process, a pressure-maintaining valve can be arranged in the outlet line of the filtrate according to the embodiments of the invention described above. However, the operating pressure can also be maintained by resistances in the subsequent pipes or filtrate consumers, such as nozzles, heat exchangers, etc.

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According to a further embodiment of the invention, in contrast to the backwash nozzle that is firmly fixed in the filter housing and arranged inside the rotatable filter insert, another nozzle is installed outside the filter insert in the housing wall, to which an inlet line is connected. Ultrasonic oscillating elements are provided in the housing wall according to one of the described arrangements. Preferably, a row of ultrasonic oscillating elements is arranged at a certain distance from the nozzles with respect to the direction of rotation of the filter insert.

This embodiment of the invention is advantageously used when, for technical reasons, sufficient pressure cannot be maintained at the outlet line of the filter and the filtrate pressure is not sufficient for direct backwashing. This is the case, for example, when the filtrate flows into a filtrate container almost without pressure.

To set the pressure required for the backwash process, a backwash liquid is fed under pressure through the inlet line of the outer nozzle, which passes through the filter insert into the inner backwash nozzle, whereby the contaminants dissolved by ultrasound are

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the inner backwash nozzle is flushed and transported away via the flushing line. The backwash liquid can be filtrate, which is brought to the necessary flushing pressure by a pump, or a pressurized external liquid.

Embodiments of the invention are explained in more detail below with reference to drawings.

Fig. 1 shows an axial section through a nozzle backwash filter according to the invention.

Fig. 2 shows a cross-section through a nozzle backwash filter according to Fig. 1.

Fig. 3 shows an axial sectional view of another embodiment of the nozzle backwash filter according to the invention.

Fig. 4 shows a cross-section through a nozzle backwash filter according to Fig. 3.

Fig. 5 to 10 show cross sections of further embodiments of the nozzle backwash filter according to the invention.

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In Fig. 1, a nozzle backwash filter is shown with an essentially cylindrical filter housing 10, which has front housing walls 11, 12 and a peripheral wall 13. A filter insert 14 with a filter medium 15 is arranged in the filter housing 10. On the inside of the filter insert 14, adjacent to the filter medium 15, passages 16 are provided in the wall of the filter insert.

The filter insert separates an inlet area 17 located inside the filter insert from an outlet area 18 located outside the filter insert. Close to the inside of the filter insert, a flushing gap 20 is provided, which is designed as the mouth of a backwash nozzle 21 and extends essentially over the entire axial length of the filter insert. According to Fig. 2, the flushing gap 20 has a relatively narrow circumferential width, so that only a narrow axial section of the filter insert is covered by the flushing gap on the inside.

The backwash nozzle 21 is arranged to rotate around an axis 22 of the filter insert 14. The nozzle 21 is seated on a shaft 23 coaxial with the axis 22, which is rotatably and sealed in pivot bearings 24, 25 of the front housing walls 11, 12. The direction of rotation of the backwash nozzle is indicated by the arrow 26 in Fig. 2. A drive 27

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for the backwash nozzle 21, only partially shown in Fig. 1, is mounted below the backwash filter.

The shaft 23 has a cavity which is connected to the flushing gap 20 via the interior of the backwash nozzle 21 and to a chamber 28 via the lower end of the shaft, to which a flushing line 29 is connected. The flushing line 29 can be closed or opened by a flushing valve (not shown).

The inlet area 17 is connected to an inlet line 30, through which liquid to be filtered is supplied. An outlet line 31 is connected to the outlet section 18, through which the filtered liquid flows out. A pressure-maintaining valve (not shown) is assigned to the outlet line 31 to maintain an operating pressure during the filtration process.

Ultrasonic oscillator elements 40 are installed in the peripheral wall 13 of the filter housing 10 and are excited by an ultrasonic generator (not shown) during the backwashing process. The ultrasonic oscillator elements 40 are arranged concentrically around the filter insert 14 and extend in height essentially in accordance with the axial length of the filter insert. The inner side

te 41 of the peripheral wall 13 of the filter housing 10 is designed such that the sound waves emanating from the ultrasonic oscillating elements propagate via the output region 18 and subject the filter medium 15 in the filter insert 14 to ultrasound.

The operation of the described filter is as follows:
The liquid to be cleaned is introduced under pressure through the inlet line 30 into the nozzle backwash filter and flows via the inlet area 17 inside the filter insert 14 through the filter medium 15 into the outlet area 18. Contaminants are retained on the inside of the filter insert 14. The filtrate exits the filter via the outlet line 31. During the filtration process, the flushing line 29 is closed.

If the filter is to be backwashed, the flushing line 29 is opened, the backwash nozzle 21 is rotated and the ultrasonic oscillator elements 40 are excited by the ultrasonic generator. The pressure inside the backwash nozzle 21 drops and the filtered liquid, which is under a higher operating pressure, flows back through the filter insert into the flushing gap 20 and from there through the nozzle into the open flushing line 29.

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the dirt adhering to the inside of the filter insert 14 is washed away. Since the filter insert is evenly exposed to a high ultrasonic power density by the ultrasonic oscillating elements, even strongly adhering solids are released from the filter medium, whereby this is guaranteed even with very fine fabrics.

According to Fig. 2, the ultrasonic oscillating elements are arranged concentrically at the same distance around the filter insert, whereby the width of the output area 18 is selected so that a high ultrasonic power density is applied to the filter insert, but on the other hand the filtrate can drain off properly during the filtration process. The concentric arrangement of the ultrasonic oscillating elements and the rotation of the backwash nozzle ensure that the entire inner peripheral area of the filter insert is cleaned.

In the nozzle backwash filter shown in Fig. 3, a backwash nozzle 121 is fixed in a filter housing 100 and the filter insert 114 surrounding the nozzle is arranged so that it can rotate, so that during the backwash process the filter insert rotates around the stationary flushing gap 120 of the backwash nozzle 121. An output line 131 is arranged above an input line 130 on the same side of the filter.

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net. A flushing line 129 is connected to the lower end of the backwash nozzle 121. A drive 127 for the filter insert 114 is provided above the filter.

In this embodiment, ultrasonic oscillator elements 140a are arranged parallel to the longitudinal axis of the filter insert in a row opposite the lines 130, 131 in the filter housing 100 of the filter.

In the embodiment according to Fig. 3, the relative movement between the backwash nozzle and the filter insert is the same as in the embodiment according to Fig. 1. Thus, the backwash intensities are also identical. In the nozzle backwash filter according to Fig. 3, the filter insert is moved through a zone of high ultrasonic power density during the backwash process, so that every part of the filter fabric is exposed to high ultrasonic energy.

According to Fig. 3 and 4, a series of ultrasonic oscillating elements 140a is arranged opposite the flushing gap 120 of the nozzle 121, so that when the filter insert is rotated, shown by the arrow 126, the entire peripheral area of the filter insert is exposed to ultrasound. The contaminants thus detached are carried away by the backwash flow from the

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- 17 backwash nozzle removed.

In the embodiment according to Fig. 5, a row of ultrasonic vibrating elements 140b is arranged at a certain distance from the rinsing gap 120 of the nozzle 121 with respect to the direction of rotation 126 of the filter insert.

In the embodiment according to Fig. 6, ultrasonic oscillator elements 140c are installed in a bar 142, which is radially displaceable in the housing wall 100. With this arrangement, the distance of the ultrasonic oscillator elements to the filter medium can be changed.

In the embodiments of the nozzle backwash filter according to Figures 7 to 9, two rows of ultrasonic oscillating elements are provided to increase the ultrasonic intensity, which are installed in a housing wall 200 parallel to the longitudinal axis of the filter insert 214. The filter insert 214 is arranged so as to be rotatable around a stationary backwash nozzle 221 with a flushing gap 220. The direction of rotation of the filter insert is shown by the arrow 226.

According to Fig. 7, a series of ultrasonic vibrating elements 240a is provided opposite the rinsing gap 220, while

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while a second row of vibrating elements 241a is arranged at a certain distance in front of the flushing gap.

In the embodiments according to Figs. 8 and 9, two rows of ultrasonic oscillator elements are installed in the housing wall 200 in such a way that the ultrasonic axes of action overlap in the filter insert 214 to be cleaned. This results in a further increase in the ultrasonic power density. The arrangement of the oscillator elements is such that the axes of action of the two rows of ultrasonic oscillator elements 240b, 241b intersect in the filter insert and immediately in front of the rinsing gap 220, while according to Fig. 9, the axes of action of the oscillator elements 240c, 241c overlap at a certain distance in front of the rinsing gap 220 in relation to the direction of rotation 226 of the filter insert.

In the embodiment according to Fig. 10, a backwash nozzle 321 is fixed in a filter housing and a filter insert 314 surrounding the backwash nozzle is arranged so as to be rotatable. Opposite the fixed, inner backwash nozzle 321, a nozzle 351 is installed outside the filter insert 314 in a housing wall 300, to which an inlet line 352 is connected. The outer nozzle 351 has a flushing gap 350 which is directly opposite the

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Flushing gap 320 of the inner backwash nozzle 321. A row of ultrasonic oscillating elements 340 is arranged at a certain distance from the nozzle gaps 320, 350 with respect to the direction of rotation 326 of the filter insert 314.

A backwash liquid is supplied under pressure through the inlet line 352 of the outer nozzle 351, which passes through the flushing gap 350 through the filter insert 314 and the flushing gap 320 into the inner backwash nozzle 321. The contaminants dissolved by ultrasound are flushed from the rotating filter insert 314 into the inner nozzle 321 and transported away via an open flushing line.

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Claims (13)

- 20 claims 1. Nozzle backwash filter with a filter housing, a filter insert arranged in the filter housing with a filter medium for filtration and a backwash nozzle for removing contaminants adhering to the filter insert, characterized in that the filter has ultrasonic vibrating elements (40, 140a-c, 240a-c, 241a-c, 340) which are arranged adjacent to the filter insert (14, 114, 214, 314) and which are excited by an ultrasonic generator. 2. Nozzle backwash filter according to claim 1, characterized in that the ultrasonic oscillating elements surround the filter insert from the outside. 3. Nozzle backwash filter according to claim 1 or 2, characterized in that the backwash nozzle (21) is arranged rotatably within the filter insert or rotatably between the filter insert and the filter housing (10, 100, 200). 4. Nozzle backwash filter according to claim 1 or 2, characterized in that the inside of the filter insert or between the filter insert and the filter housing arranged backwash nozzle (121, 221, 321) is attached to the filter housing (100, 200, 300) and the filter insert (114, 214, 314) is rotatably arranged in the filter housing. 5. Nozzle backwash filter according to claim 4, characterized in that a nozzle (351) is attached to the filter housing (300) opposite the backwash nozzle (321) arranged inside the filter insert (314) and an inlet line (352) is connected to the outer nozzle (351). 6. Nozzle backwash filter according to claim 4, characterized in that a row of ultrasonic oscillator elements (140a) is arranged opposite the backwash nozzle (121). 7. Nozzle backwash filter according to one of claims 1 to 5, characterized in that at least one row of ultrasonic oscillating elements (140b-c, 240a-c, 241a-c, 340) is provided parallel to the longitudinal axis of the filter insert. 8. Nozzle backwash filter according to claim 7, characterized in that in the direction of rotation (126, 326) of the filter .../22 insert (114, 314) a series of ultrasonic oscillating elements (140b, 340) is arranged at a certain distance from the backwash nozzle (121, 321). 9. Nozzle backwash filter according to claim 7, characterized in that at least two rows of ultrasonic oscillating elements (24 0b, c; 241b, c) are arranged relative to one another in such a way that the axes of action of the oscillating elements overlap in the filter medium to be cleaned. 10. Nozzle backwash filter according to claim 9, characterized in that the intersection of the axes of action takes place immediately in front of the backwash nozzle (221). 11. Nozzle backwash filter according to claim 9, characterized in that in the direction of rotation (226) of the filter insert (214) the intersection of the axes of action takes place at a certain distance from the backwash nozzle (221). 12. Nozzle backwash filter according to one of claims 4 to 11, characterized in that the backwash nozzle (121, 221, 321) is detachably attached to the filter housing. .../23 13. Nozzle backwash filter according to one of claims 1 to 12, characterized in that the ultrasonic oscillator elements (140c) are arranged to be displaceable in the direction of the filter insert (114).