Title of Invention	FILTER ARRANGEMENT FOR CLEANING PROCESS GASES CONTAMINATED WITH PARTICLES, AND PROCESS FOR CLEANING FILTER UNITS OF SUCH A FILTER ARRANGEMENT
Abstract	In order to improve a cleaning of filter units of a filter arrangement of a process container provided for the treatment of a product at the site of the filter units without disassembly of the same (cleaning in place - CIP), the invention provides a filter arrangement for cleaning gases contaminated with particles, having at least one filter unit comprising an exterior and an interior filter (3.1, 3.2), wherein the exterior and interior filters can be moved relative to each other, thereby exposing an opening (3.4) in the bottom regions thereof. A method for cleaning according to the invention is further characterized in that the region of the filter unit on the clean gas side is cleaned by cleaning fluid sprayed by means of a cleaning lance protruding into the clean gas region while exposing a gap (3.4) in the bottom region of the exterior and interior filters.

Title of Invention

FILTER ARRANGEMENT FOR CLEANING PROCESS GASES CONTAMINATED WITH PARTICLES, AND PROCESS FOR CLEANING FILTER UNITS OF SUCH A FILTER ARRANGEMENT

Abstract

In order to improve a cleaning of filter units of a filter arrangement of a process container provided for the treatment of a product at the site of the filter units without disassembly of the same (cleaning in place - CIP), the invention provides a filter arrangement for cleaning gases contaminated with particles, having at least one filter unit comprising an exterior and an interior filter (3.1, 3.2), wherein the exterior and interior filters can be moved relative to each other, thereby exposing an opening (3.4) in the bottom regions thereof. A method for cleaning according to the invention is further characterized in that the region of the filter unit on the clean gas side is cleaned by cleaning fluid sprayed by means of a cleaning lance protruding into the clean gas region while exposing a gap (3.4) in the bottom region of the exterior and interior filters.

Full Text	Filter Arrangement for Cleaning Process Gases Contaminated with Particles and Process for Cleaning Filter Units of Such a Filter Arrangement The present invention pertains to a filter arrangement for cleaning gases contaminated with particles, with at least one filter unit with an exterior filter and an interior filter as well as to a process for cleaning at least one filter unit with an exterior filter and an interior filter of a filter arrangement, which said interior filter is arranged in said exterior filter. The present invention pertains to a filter arrangement, which is arranged above and on a process container, in which particulate product is treated, e.g., by mixing, drying, granulation, pelletizing and/or coating the product. The process may consist of agglomerating or granulating product particles having the fineness of dust in the process container into larger particles or of providing particulate starting product with a coat by means of coating. A bottom, which is permeable to air and has passages, especially in the form of slots, is usually provided for this in the lower region of the process container. A filter unit, comprising a cylindrical exterior filter and an interior filter tapering conically from bottom to top, is known from DE 40 29 994 C2. Air contaminated with particles, such as dusty air, is delivered in the product-treating process operation from the outside through the exterior filter and from the inside through the interior filter into an intermediate space between the exterior filter and the interior filter of the filter unit and via an opened valve to a gas outlet. To blow off dust collected on the outside of the exterior filter and on the inside of the interior filter, the valve is closed and an air path from a gas inlet for clean gas to the intermediate space between the interior filter and the exterior filter is opened via another valve, so that blowing off of particles adhering to the outside of the exterior filter and to the inside of the interior filter can take place in counterflow. Complete cleaning is not always possible hereby on the side of the filters facing the dusty air, and removal of filter dust having penetrated into the clean air region can be performed with difficulty only. For complete cleaning, the filter unit must be removed and disassembled and the individual filters must then be cleaned one by one. Consequently, cleaning in place (CIP) is not possible in the state of the art without removal of the filter cartridges. The basic object of the present invention is therefore to provide a filter arrangement of the type mentioned in the introduction, which and especially the filter units of which can be cleaned completely and comprehensively in place, and to propose a process for carrying out such cleaning. Said object is accomplished according to the present invention in a filter arrangement of the type mentioned in the introduction by the exterior filter and the interior filter being able to be moved in relation to be another, thereby exposing a gap in their lower regions. For cleaning, the present invention provides for a process of the above-mentioned type, in which provisions are fundamentally made for the region of the filter unit on the clean gas side to be cleaned [by means of- word(s) missing in German original - Tr.Ed.] cleaning fluid sprayed while exposing a gap in the lower regions of the exterior filter and interior filter. This can be carried out especially by means of a cleaning lance protruding into the clean gas region. Due to the fact that the two individual filters of the filter unit of the filter arrangement according to the present invention, namely, the interior filter and the exterior filter, are not connected rigidly to one another but a gap or slot can be exposed at the site in the lower regions thereof by a relative motion, it is possible, on the one hand, to carry out cleaning, as it is provided for according to the above fundamental process step, by means of (CIP) fluid sprayed into the clean space region between the interior filter and the exterior filter and for the contaminants entrained by said fluid to leave the filter unit through the gap, after which they can be further removed via the process arrangement. Furthermore, it is possible to perform ultrasonic cleaning if the filter unit is equipped with metal filters, for which a liquid coupling medium is necessary between the interior filter and the exterior filter, ["which" - word missing in German original - Tr.Ed.] can be filled into the intermediate space such that more fluid is fed than can be discharged through the filters themselves, wherein an ultrasound transducer protrudes into the coupling medium to generate the ultrasound in said coupling medium and the coupling fluid can finally flow off again together with contaminants removed from the filters through the gap by opening said gap after the cleaning. Finally, it is possible to carry out a drying of the filters on the inside and outside with the gap opened by drying air flowing in from the slotted disk of the process arrangement. In a variant, the present invention provides for the exterior filter and the interior filter to be able to be moved relative to one another while exposing an annular gap, wherein especially the interior filter can be lifted off relative to the exterior filter or the interior filter can be lowered relative to the exterior filter. The drive for generating the relative motion between the interior filter and the exterior filter is brought about by a drive means outside the filter unit, for example, via an actuating rod. To fully utilize the possibility of cleaning created by the embodiment of the filter arrangement according to the present invention, the present invention provides, in a variant, for a means for blowing fluid, especially gas, into the region of the filter unit on the clean gas side and for a means for closing off the region of the filter unit on the clean space side against an outlet and by [sic - Tr.Ed.] a lance protruding in the region of the filter unit on the clean space side for spraying cleaning liquid into this region of the filter unit as well as by [sic - Tr.Ed.] a cleaning lance protruding into the exterior space of the at least one filter unit, which said exterior space faces away from the clean side, especially into a filter dome surrounding this [filter unit] for cleaning the sides of the filter unit exposed to the gas contaminated with particles by means of a liquid. Provisions are made in a variant of the process according to the present invention for the gap in the lower region between the exterior filter and the interior filter of the at least one filter unit to be opened by lowering or raising the interior filter in relation to the exterior filter and to be closed by an opposite motion. Cleaning steps can be provided within the framework of the process according to the present invention such that cleaning gas is blown into the filter unit preferably in advance, while a gas outlet is closed, from the region of the filter unit on the clean space side and through the filters of said filter unit against the direction of flow during the cleaning operation of said filter unit; that regions of the filter facing away from the clean gas space are cleaned by means of a cleaning liquid ejected from a cleaning lance, and that, as was already stated, drying of the at least one filter unit is performed while opening the gap between the exterior filter and the interior filter. For cleaning by mans of ultrasound, the present invention makes provisions, prior to the drying, for metal filters of the filter unit to be cleaned by introducing a coupling liquid into the intermediate space between the exterior filter and the interior filter with the gap between the two filters closed by means of an ultrasound source protruding into the intermediate space. Other advantages and features of the present invention appear from the claims and from the following description, in which exemplary embodiments of the present invention are explained in detail with reference to the drawings. Specifically, Figure 1 shows a schematic vertical longitudinal section through a filter arrangement according to the present invention on a process container; Figure 2 shows a longitudinal section through the top side of a filter dome with two filter units, of which the one on the right-hand side filters process air, while the one on the left-hand side is switched for cleaning the filters; Figure 3 shows a longitudinal section through the filter arrangement according to the present invention with view of the clean gas side cleaning of the filters by means of cleaning liquid; Figure 4 shows a filter arrangement, which is additionally provided with an ultrasound source for ultrasonic cleaning in case of metal filters; Figure 5 shows a view of the filter arrangement according to the present invention to illustrate the drying operation of the filters; Figure 6 shows alternative embodiments of the relative mobility of the interior and exterior filters of the filter units; and Figure 7 shows alternative embodiments of the relative mobility of the interior and exterior filters of the filter units with a lowerable intermediate bottom. Figure 1 shows the filter arrangement 1 according to the present invention arranged on a process container 2 tapering conically from top to bottom. For example, particulate matter is treated in such a process container 2, e.g., by mixing, drying, granulating, pelletizing and/or coating the product. Thus, product particles having the fineness of dust can be agglomerated and thus granulated in the process container ["in den" in line 31, p. 6 is a typo for "in dem" or "im" - Tr.Ed.] into larger particles, or else particulate starting product can be provided with a coat by coating. A bottom 2.1, which is permeable to air and has passages, especially in the form of slots, is usually provided for this in the lower region of the process container 2. Nozzles, which make it possible to spray on a coating medium, may be arranged integrated in said bottom or in the cylindrical wall. The filter arrangement 1 according to the present invention has a plurality of, usually three to six, filter units 3 in a housing-like filter dome 1.1. Such a filter unit 3 has an exterior filter filter [sic - Tr.Ed.] 3.1 and an interior filter 3.2, wherein said exterior filter 3.1 is usually cylindrical and is cylindrical in the exemplary embodiment being shown, whereas said interior filter 3.2 is usually conical and is conical, namely, tapering from top to bottom, in the exemplary embodiment being shown. In the process operation, i.e., when the filter units 3 clean or remove dust from air contaminated with dust or from a gas contaminated with dust, which air is present in the process container 2 and in the filter dome 1.1, the lower edges of the exterior filter 3.1 and interior filter 3.2 are aligned with one another and are connected to one another via a closed annular area 3.4, as this corresponds to the state of the art. The top side of the interior filter 3.2 ends below the top end of the exterior filter 3.1. The filter area is markedly enlarged, nearly doubled, by the filter unit 3 designed in such a way as a double filter with an exterior filter 3.1 and an interior filter 3.2 compared to a, for example, cylindrical single filter. The ring jacket-like intermediate space 3.5 between the exterior filter and interior filter 3.1, 3.2, into which the clean air flows through the filters, is in connection with an outlet region 3.6 for the clean air above the interior filter 3.2, which [region] is in turn in fluid connection with a exhaust air tube 3.8 via a flap 3.7, which is to be opened. The interior filter 3.2 is connected via an actuating rod 3.3.1 to a drive 3.3.2, by which the interior filter 3.1 [sic - Tr.Ed.] can be lowered in the exemplary embodiment shown in Figure 1 or - in the exemplary embodiment to the left in Figures 6 and 7 - also raised, as a result of which an annular gap 3.9 is opened to the intermediate space 3.5 between the exterior and interior filters 3.1, 3.2 between the lower regions of the exterior and interior filters 3.1, 3.2. The drive may be, for example, a hydraulic or pneumatic drive with a piston-and-cylinder arrangement or also an electric drive, be it an electric motor drive or an electromagnetic drive. Furthermore, a cleaning device 4 is provided, which has a fluid feed line 4.1 and a lance 4.2, which protrudes into the outlet region 3.6 and cylindrically surrounds the drive rod 3.3.1 in the exemplary embodiment being shown and has a discharge opening at its top end, at a vertically spaced location from the top side of the interior filter 3.2.The clean air side of the filters can be cleaned hereby as this will be described below. A cleaning lance 5.1 with an outlet 5.2 for a cleaning fluid protrudes into the exhaust air space 3.6 for the process gas. Finally, a straight-jet nozzle cleaner 6 with a liquid feed 6.1, with a lance 6.2 protruding approximately centrally into the filter dome 1.1 and with a discharge nozzle 6.3 arranged at the end of lance 6.2 is located in the lower region of the filter dome 1.1. As will be described below, cleaning of the outside of the filters 3.2, 3.3 can be carried out hereby. The filters are metal filters in the embodiment according to Figure 4, i.e., they are screen-covered. The present invention provides for an ultrasound transducer 7 protruding into the intermediate space of each filter unit 3 between the exterior and interior filters 3.1, 3.2 for additional cleaning in this case. A liquid, such as a CIP liquid 8, is filled in as a coupling medium between the ultrasound transducer 7 and the filters 3.1, 3.2. Figure 5 shows that dry air is blown in the space between the interior of the filter dome 1.1 through the air-permeable bottom 2.1 to dry the filters 3.1, 3.2, especially if they are fabric filters, but also in case of metal filters with the process space emptied. The process for cleaning the filter unit equipped in this manner according to the present invention takes place as follows: During the operation process, during which particulate product is being treated in the process container 2 in the above-described manner by blowing in air or gas through the air-permeable bottom 2.1, this gas enters the interior of the filter unit 3, as this can be seen especially in the filter unit 3 on the right-hand side in Figure 2, from the outside through the exterior filter 3.1 and from the inside through the interior filter 3.2 and is cleaned in the process by the filters 3.1, 3.2. It flows through the outlet region 3.6 and escapes via the exhaust air tube 3.8 of the filter arrangement 1 with the flap 3.7 open, after which it can be returned via bottom 2.1. If the filters 3.1, 3.2 are to be cleaned in place (CIP = cleaning in place), flap 3.7 in the exhaust gas duct 3.8 is closed for a first cleaning step and cleaning fluid, such as air or an inert gas is subsequently blown into the interior of filter unit 3 and hence through the filters 3.1, 3.2 from the clean gas side via the fluid feed line 4.1 and lance 4.2, as this is shown in Figure 1 and on the left- hand side of Figure 2, so that material adhering on the process side of these filters, such as granulating material, coating material or the like, is blown off from the filters. The interior and exterior filters 3.1, 3.2 are now in a relative position, in which the annular gap 3.9 on their undersides is closed. In a next step - in the embodiment according to Figure 3 - the interior filter 3.2 is raised by drive 3.3.2 by means of the actuating rod 3.3.1 in relation to the exterior filter 3.2 (Figure 3), so that the annular gap 3.9 is opened. Cleaning liquid, so-called CIP liquid, is subsequently sprayed into the interior space of the exterior filter 3.1 and into the intermediate space between this and the interior filter 3.2 via the cleaning lance 5.1, so that material that may adhere on the inside of the exterior filter 3.1 and/or on the radially outer side of the interior filter 3.2 can be flushed out via the annular gap 3.9. As was stated, an ultrasound transducer protruding into the intermediate space between the exterior and interior filters 3.1, 3.2 may be provided for further cleaning if the filters 3.1, 3.2 are metal filters. Liquid continues to be sprayed in this case into the interior space of the filter unit with the annular gap 3.9 closed, the quantity of such liquid sprayed exceeding the quantity that can flow off through the filters, as a result of which liquid 8 will collect in the interior space, and this liquid will act as a coupling medium for the ultrasound. The ultrasound transducer 7 is activated and effective removal of material adhering to the inside of the exterior filter 3.1 and to the outside of the interior filter 3.2, such as coating material or the like, takes place, and such material migrates into the liquid 8. This [liquid] can then be drained off by raising - in the embodiment according to Figure 3 - the interior filter 3.2 relative to the exterior filter 3.1 by means of drive 3.3.2 and by mediation by the actuating rod 3.3.1. In a next step, which is shown in Figure 1, the outside of the exterior filter 3.1 and the inside of the interior filter 3.2 are cleaned by means of the straight-jet nozzle cleaner 6 by means of liquid (CIP liquid) fed via the liquid feed 6.1 thereof via said lance 6.2 thereof and said discharge nozzle 6.3. Finally, drying of the entire interior space of the filter arrangement 1 and especially of the filter units 3 is carried out (Figure 5) by dry air or dry gas fed via the slotted bottom 2.1. Figure 6 shows on the right-hand side an alternative embodiment of a filter unit according to the present invention for comparison with the filter unit that is embodied in the embodiment on the left- hand side of Figures 1 through 5 and is described in detail there. Filter unit 3' on the right-hand side of Figure 6 has fundamentally the same design as the filter unit 3 and has the same elements, which are provided with the same reference numbers. Only the interior filter 3.2 can be lowered rather than raised in relation to the exterior filter to generate the slot-like gap 3.9. With the two alternatives of the interior filter 3.2 that can be raised or lifted off, Figure 7 shows another alternative embodiment, in which a lowerable intermediate bottom is provided in the filter dome 1.1 above the filters 3 or exterior filters 3.1. List of Reference Numbers 1 Filter arrangement 1.1 Filter dome 2 Process container 2.1 Bottom 2.2 Cone 3, 3' Filter units 3.1 Exterior filter 3.2 Interior filter 3.3.1 Actuating rod, drive rod 3.3.2 Drive 3.4 Annular region 3.5 Intermediate space 3.6 Outlet region, exhaust air space 3.7 Flap 3.8 Exhaust gas duct 3.9 Annular gap 4 Cleaning device 4.1 Fluid feed line 4.2 Lance 5.1 Cleaning lance 5.2 Outlet 6 Straight-jet nozzle cleaner 6.1 Liquid feed 6.2 Lance 6.3 Discharge nozzle 7 Ultrasound transducer 8 (CIP) liquid WE CLAIM 1. Filter arrangement for cleaning gases contaminated with particles, with at least one filter unit (3) with an exterior filter and an interior filter (3.1, 3.2), characterized in that the exterior and interior filters (3.1, 3.2) can be moved relative to one another while exposing a gap in the lower region thereof. 2. Arrangement in accordance with claim 1, characterized in that the exterior and interior filters (3.1, 3.2) can be moved relative to one another while exposing an annular gap (3.9). 3. Arrangement in accordance with claim 1 or 2, characterized in that the interior filter (3.2) can be raised relative to the exterior filter (3.1). 4. Arrangement in accordance with claim 1 or 2, characterized in that the interior filter (3.2) can be lowered relative to the exterior filter (3.1). 5. Arrangement in accordance with one of the claims 1 through 4, characterized in that a drive is provided outside the filter unit (3) for the relative motion between the exterior and interior filters (3.1, 3.2). 6. Arrangement in accordance with one of the above claims, characterized by a means (4, 4.1, 4.2) for blowing in fluid, especially gas, into the region (3.5, 3.6) of the filter unit (3) on the clean gas side and by a means (3.7) for closing the region (3.5, 3.6) of the filter unit (3) on the clean space side against an outlet (3.8). 7. Arrangement in accordance with one of the above claims, characterized by a liquid line leading into the region (3.5, 3.6) of the filter unit (3) on the clean space side. 8. Arrangement in accordance with claim 7, characterized by a lance or spray head (5.1, 5.2) protruding into the region (3.5, 3.6) of the filter unit on the clean space side for spraying cleaning liquid into said region of the filter unit (3). 9. Arrangement in accordance with one of the above claims, characterized by an ultrasound transducer (7) protruding into an intermediate space between the exterior and interior filters (3.1, 3.2) for the ultrasonic cleaning of the filters (3.1, 3.2). 10. Arrangement in accordance with one of the above claims, characterized by a cleaning lance (5.2) protruding into the exterior space of the at least one filter unit (3), which said exterior space faces away from the clean gas side (3.5, 3.6), especially into a filter dome (1.1) surrounding same [said filter unit (3)], for cleaning the sides of the filter unit (3) exposed to the gas contaminated with particles by means of a liquid. 11. Process for cleaning at least one filter unit (3) with an exterior filter (3.1) and with an interior filter (3.2) of a filter arrangement, which said interior filter is located in said exterior filter, characterized in that the region (3.5, 3.6) of the filter unit (3) on the clean gas side is cleaned [by means of] a cleaning fluid sprayed while a gap is exposed in the lower region of the exterior and interior filters (3.1, 3.2). 12. Process in accordance with claim 11, characterized in that cleaning gas is blown into the filter unit (3.5 [sic - Tr.Ed.]) and against the direction of flow preferably in advance, while closing a gas outlet (3.8) from the region (3.5, 3.6) of the filter unit (3) on the clean space side during the cleaning operation of said filter unit through the filters (3.1, 3.2) of said filter unit. 13. Process in accordance with claim 11 or 12, characterized in that metal filters of the filter unit (3) are cleaned by means of an ultrasound lance protruding into the intermediate space while introducing a coupling liquid into the intermediate space between the exterior and interior filters (3.1, 3.2) with the gap (3.9) between the two filters (3.1, 3.2) closed. 14. Process in accordance with one of the claims 11 through 13, characterized in that regions of the filter facing away from the clean gas space (3.5, 3.6) are cleaned by means of a cleaning liquid ejected from a cleaning lance. 15. Process in accordance with one of the claims 11 through 14, characterized in that drying of the at least one filter unit (3) is carried out while opening the gap between the exterior and interior filters (3.1, 3.2). 16. Process in accordance with one of the claims 11 through 15, characterized in that the gap in the lower region between the external and internal filters (3.1, 3.2) of the at least one filter unit (3) is opened by lowering or raising the interior filter (3.2) in relation to the exterior filter (3.1) and closed by an opposite motion. In order to improve a cleaning of filter units of a filter arrangement of a process container provided for the treatment of a product at the site of the filter units without disassembly of the same (cleaning in place - CIP), the invention provides a filter arrangement for cleaning gases contaminated with particles, having at least one filter unit comprising an exterior and an interior filter (3.1, 3.2), wherein the exterior and interior filters can be moved relative to each other, thereby exposing an opening (3.4) in the bottom regions thereof. A method for cleaning according to the invention is further characterized in that the region of the filter unit on the clean gas side is cleaned by cleaning fluid sprayed by means of a cleaning lance protruding into the clean gas region while exposing a gap (3.4) in the bottom region of the exterior and interior filters.

Full Text

Filter Arrangement for Cleaning Process Gases Contaminated with Particles
and Process for Cleaning Filter Units of Such a Filter Arrangement
The present invention pertains to a filter arrangement for cleaning gases contaminated with
particles, with at least one filter unit with an exterior filter and an interior filter as well as to a
process for cleaning at least one filter unit with an exterior filter and an interior filter of a filter
arrangement, which said interior filter is arranged in said exterior filter.
The present invention pertains to a filter arrangement, which is arranged above and on a process
container, in which particulate product is treated, e.g., by mixing, drying, granulation, pelletizing
and/or coating the product. The process may consist of agglomerating or granulating product
particles having the fineness of dust in the process container into larger particles or of providing
particulate starting product with a coat by means of coating. A bottom, which is permeable to air
and has passages, especially in the form of slots, is usually provided for this in the lower region of
the process container.
A filter unit, comprising a cylindrical exterior filter and an interior filter tapering conically from
bottom to top, is known from DE 40 29 994 C2.
Air contaminated with particles, such as dusty air, is delivered in the product-treating process
operation from the outside through the exterior filter and from the inside through the interior filter

into an intermediate space between the exterior filter and the interior filter of the filter unit and via
an opened valve to a gas outlet.
To blow off dust collected on the outside of the exterior filter and on the inside of the interior filter,
the valve is closed and an air path from a gas inlet for clean gas to the intermediate space between
the interior filter and the exterior filter is opened via another valve, so that blowing off of particles
adhering to the outside of the exterior filter and to the inside of the interior filter can take place in
counterflow. Complete cleaning is not always possible hereby on the side of the filters facing the
dusty air, and removal of filter dust having penetrated into the clean air region can be performed
with difficulty only. For complete cleaning, the filter unit must be removed and disassembled and
the individual filters must then be cleaned one by one. Consequently, cleaning in place (CIP) is not
possible in the state of the art without removal of the filter cartridges.
The basic object of the present invention is therefore to provide a filter arrangement of the type
mentioned in the introduction, which and especially the filter units of which can be cleaned
completely and comprehensively in place, and to propose a process for carrying out such cleaning.
Said object is accomplished according to the present invention in a filter arrangement of the type
mentioned in the introduction by the exterior filter and the interior filter being able to be moved in
relation to be another, thereby exposing a gap in their lower regions.
For cleaning, the present invention provides for a process of the above-mentioned type, in which
provisions are fundamentally made for the region of the filter unit on the clean gas side to be
cleaned [by means of- word(s) missing in German original - Tr.Ed.] cleaning fluid sprayed while
exposing a gap in the lower regions of the exterior filter and interior filter. This can be carried out
especially by means of a cleaning lance protruding into the clean gas region.

Due to the fact that the two individual filters of the filter unit of the filter arrangement according to
the present invention, namely, the interior filter and the exterior filter, are not connected rigidly to
one another but a gap or slot can be exposed at the site in the lower regions thereof by a relative
motion, it is possible, on the one hand, to carry out cleaning, as it is provided for according to the
above fundamental process step, by means of (CIP) fluid sprayed into the clean space region
between the interior filter and the exterior filter and for the contaminants entrained by said fluid to
leave the filter unit through the gap, after which they can be further removed via the process
arrangement. Furthermore, it is possible to perform ultrasonic cleaning if the filter unit is equipped
with metal filters, for which a liquid coupling medium is necessary between the interior filter and
the exterior filter, ["which" - word missing in German original - Tr.Ed.] can be filled into the
intermediate space such that more fluid is fed than can be discharged through the filters themselves,
wherein an ultrasound transducer protrudes into the coupling medium to generate the ultrasound in
said coupling medium and the coupling fluid can finally flow off again together with contaminants
removed from the filters through the gap by opening said gap after the cleaning. Finally, it is
possible to carry out a drying of the filters on the inside and outside with the gap opened by drying
air flowing in from the slotted disk of the process arrangement.
In a variant, the present invention provides for the exterior filter and the interior filter to be able to
be moved relative to one another while exposing an annular gap, wherein especially the interior
filter can be lifted off relative to the exterior filter or the interior filter can be lowered relative to the
exterior filter. The drive for generating the relative motion between the interior filter and the
exterior filter is brought about by a drive means outside the filter unit, for example, via an actuating
rod. To fully utilize the possibility of cleaning created by the embodiment of the filter arrangement
according to the present invention, the present invention provides, in a variant, for a means for
blowing fluid, especially gas, into the region of the filter unit on the clean gas side and for a means
for closing off the region of the filter unit on the clean space side against an outlet and by [sic -

Tr.Ed.] a lance protruding in the region of the filter unit on the clean space side for spraying
cleaning liquid into this region of the filter unit as well as by [sic - Tr.Ed.] a cleaning lance
protruding into the exterior space of the at least one filter unit, which said exterior space faces away
from the clean side, especially into a filter dome surrounding this [filter unit] for cleaning the sides
of the filter unit exposed to the gas contaminated with particles by means of a liquid.
Provisions are made in a variant of the process according to the present invention for the gap in the
lower region between the exterior filter and the interior filter of the at least one filter unit to be
opened by lowering or raising the interior filter in relation to the exterior filter and to be closed by
an opposite motion. Cleaning steps can be provided within the framework of the process according
to the present invention such that cleaning gas is blown into the filter unit preferably in advance,
while a gas outlet is closed, from the region of the filter unit on the clean space side and through the
filters of said filter unit against the direction of flow during the cleaning operation of said filter unit;
that regions of the filter facing away from the clean gas space are cleaned by means of a cleaning
liquid ejected from a cleaning lance, and that, as was already stated, drying of the at least one filter
unit is performed while opening the gap between the exterior filter and the interior filter. For
cleaning by mans of ultrasound, the present invention makes provisions, prior to the drying, for
metal filters of the filter unit to be cleaned by introducing a coupling liquid into the intermediate
space between the exterior filter and the interior filter with the gap between the two filters closed by
means of an ultrasound source protruding into the intermediate space.
Other advantages and features of the present invention appear from the claims and from the
following description, in which exemplary embodiments of the present invention are explained in
detail with reference to the drawings. Specifically,

Figure 1 shows a schematic vertical longitudinal section through a filter arrangement
according to the present invention on a process container;
Figure 2 shows a longitudinal section through the top side of a filter dome with two filter
units, of which the one on the right-hand side filters process air, while the one on the
left-hand side is switched for cleaning the filters;
Figure 3 shows a longitudinal section through the filter arrangement according to the present
invention with view of the clean gas side cleaning of the filters by means of cleaning
liquid;
Figure 4 shows a filter arrangement, which is additionally provided with an ultrasound source
for ultrasonic cleaning in case of metal filters;
Figure 5 shows a view of the filter arrangement according to the present invention to illustrate
the drying operation of the filters;
Figure 6 shows alternative embodiments of the relative mobility of the interior and exterior
filters of the filter units; and
Figure 7 shows alternative embodiments of the relative mobility of the interior and exterior
filters of the filter units with a lowerable intermediate bottom.
Figure 1 shows the filter arrangement 1 according to the present invention arranged on a process
container 2 tapering conically from top to bottom. For example, particulate matter is treated in such
a process container 2, e.g., by mixing, drying, granulating, pelletizing and/or coating the product.

Thus, product particles having the fineness of dust can be agglomerated and thus granulated in the
process container ["in den" in line 31, p. 6 is a typo for "in dem" or "im" - Tr.Ed.] into larger
particles, or else particulate starting product can be provided with a coat by coating. A bottom 2.1,
which is permeable to air and has passages, especially in the form of slots, is usually provided for
this in the lower region of the process container 2. Nozzles, which make it possible to spray on a
coating medium, may be arranged integrated in said bottom or in the cylindrical wall.
The filter arrangement 1 according to the present invention has a plurality of, usually three to six,
filter units 3 in a housing-like filter dome 1.1. Such a filter unit 3 has an exterior filter filter [sic -
Tr.Ed.] 3.1 and an interior filter 3.2, wherein said exterior filter 3.1 is usually cylindrical and is
cylindrical in the exemplary embodiment being shown, whereas said interior filter 3.2 is usually
conical and is conical, namely, tapering from top to bottom, in the exemplary embodiment being
shown.
In the process operation, i.e., when the filter units 3 clean or remove dust from air contaminated
with dust or from a gas contaminated with dust, which air is present in the process container 2 and
in the filter dome 1.1, the lower edges of the exterior filter 3.1 and interior filter 3.2 are aligned with
one another and are connected to one another via a closed annular area 3.4, as this corresponds to
the state of the art. The top side of the interior filter 3.2 ends below the top end of the exterior filter
3.1. The filter area is markedly enlarged, nearly doubled, by the filter unit 3 designed in such a way
as a double filter with an exterior filter 3.1 and an interior filter 3.2 compared to a, for example,
cylindrical single filter.
The ring jacket-like intermediate space 3.5 between the exterior filter and interior filter 3.1, 3.2, into
which the clean air flows through the filters, is in connection with an outlet region 3.6 for the clean

air above the interior filter 3.2, which [region] is in turn in fluid connection with a exhaust air tube
3.8 via a flap 3.7, which is to be opened.
The interior filter 3.2 is connected via an actuating rod 3.3.1 to a drive 3.3.2, by which the interior
filter 3.1 [sic - Tr.Ed.] can be lowered in the exemplary embodiment shown in Figure 1 or - in the
exemplary embodiment to the left in Figures 6 and 7 - also raised, as a result of which an annular
gap 3.9 is opened to the intermediate space 3.5 between the exterior and interior filters 3.1, 3.2
between the lower regions of the exterior and interior filters 3.1, 3.2. The drive may be, for
example, a hydraulic or pneumatic drive with a piston-and-cylinder arrangement or also an electric
drive, be it an electric motor drive or an electromagnetic drive.
Furthermore, a cleaning device 4 is provided, which has a fluid feed line 4.1 and a lance 4.2, which
protrudes into the outlet region 3.6 and cylindrically surrounds the drive rod 3.3.1 in the exemplary
embodiment being shown and has a discharge opening at its top end, at a vertically spaced location
from the top side of the interior filter 3.2.The clean air side of the filters can be cleaned hereby as
this will be described below.
A cleaning lance 5.1 with an outlet 5.2 for a cleaning fluid protrudes into the exhaust air space 3.6
for the process gas.
Finally, a straight-jet nozzle cleaner 6 with a liquid feed 6.1, with a lance 6.2 protruding
approximately centrally into the filter dome 1.1 and with a discharge nozzle 6.3 arranged at the end
of lance 6.2 is located in the lower region of the filter dome 1.1. As will be described below,
cleaning of the outside of the filters 3.2, 3.3 can be carried out hereby.

The filters are metal filters in the embodiment according to Figure 4, i.e., they are screen-covered.
The present invention provides for an ultrasound transducer 7 protruding into the intermediate
space of each filter unit 3 between the exterior and interior filters 3.1, 3.2 for additional cleaning in
this case. A liquid, such as a CIP liquid 8, is filled in as a coupling medium between the ultrasound
transducer 7 and the filters 3.1, 3.2.
Figure 5 shows that dry air is blown in the space between the interior of the filter dome 1.1 through
the air-permeable bottom 2.1 to dry the filters 3.1, 3.2, especially if they are fabric filters, but also
in case of metal filters with the process space emptied.
The process for cleaning the filter unit equipped in this manner according to the present invention
takes place as follows:
During the operation process, during which particulate product is being treated in the process
container 2 in the above-described manner by blowing in air or gas through the air-permeable
bottom 2.1, this gas enters the interior of the filter unit 3, as this can be seen especially in the filter
unit 3 on the right-hand side in Figure 2, from the outside through the exterior filter 3.1 and from
the inside through the interior filter 3.2 and is cleaned in the process by the filters 3.1, 3.2. It flows
through the outlet region 3.6 and escapes via the exhaust air tube 3.8 of the filter arrangement 1
with the flap 3.7 open, after which it can be returned via bottom 2.1.
If the filters 3.1, 3.2 are to be cleaned in place (CIP = cleaning in place), flap 3.7 in the exhaust gas
duct 3.8 is closed for a first cleaning step and cleaning fluid, such as air or an inert gas is
subsequently blown into the interior of filter unit 3 and hence through the filters 3.1, 3.2 from the
clean gas side via the fluid feed line 4.1 and lance 4.2, as this is shown in Figure 1 and on the left-

hand side of Figure 2, so that material adhering on the process side of these filters, such as
granulating material, coating material or the like, is blown off from the filters.
The interior and exterior filters 3.1, 3.2 are now in a relative position, in which the annular gap 3.9
on their undersides is closed.
In a next step - in the embodiment according to Figure 3 - the interior filter 3.2 is raised by drive
3.3.2 by means of the actuating rod 3.3.1 in relation to the exterior filter 3.2 (Figure 3), so that the
annular gap 3.9 is opened. Cleaning liquid, so-called CIP liquid, is subsequently sprayed into the
interior space of the exterior filter 3.1 and into the intermediate space between this and the interior
filter 3.2 via the cleaning lance 5.1, so that material that may adhere on the inside of the exterior
filter 3.1 and/or on the radially outer side of the interior filter 3.2 can be flushed out via the annular
gap 3.9.
As was stated, an ultrasound transducer protruding into the intermediate space between the exterior
and interior filters 3.1, 3.2 may be provided for further cleaning if the filters 3.1, 3.2 are metal
filters. Liquid continues to be sprayed in this case into the interior space of the filter unit with the
annular gap 3.9 closed, the quantity of such liquid sprayed exceeding the quantity that can flow off
through the filters, as a result of which liquid 8 will collect in the interior space, and this liquid will
act as a coupling medium for the ultrasound. The ultrasound transducer 7 is activated and effective
removal of material adhering to the inside of the exterior filter 3.1 and to the outside of the interior
filter 3.2, such as coating material or the like, takes place, and such material migrates into the liquid
8.
This [liquid] can then be drained off by raising - in the embodiment according to Figure 3 - the
interior filter 3.2 relative to the exterior filter 3.1 by means of drive 3.3.2 and by mediation by the
actuating rod 3.3.1.

In a next step, which is shown in Figure 1, the outside of the exterior filter 3.1 and the inside of the
interior filter 3.2 are cleaned by means of the straight-jet nozzle cleaner 6 by means of liquid (CIP
liquid) fed via the liquid feed 6.1 thereof via said lance 6.2 thereof and said discharge nozzle 6.3.
Finally, drying of the entire interior space of the filter arrangement 1 and especially of the filter
units 3 is carried out (Figure 5) by dry air or dry gas fed via the slotted bottom 2.1.
Figure 6 shows on the right-hand side an alternative embodiment of a filter unit according to the
present invention for comparison with the filter unit that is embodied in the embodiment on the left-
hand side of Figures 1 through 5 and is described in detail there.
Filter unit 3' on the right-hand side of Figure 6 has fundamentally the same design as the filter unit
3 and has the same elements, which are provided with the same reference numbers. Only the
interior filter 3.2 can be lowered rather than raised in relation to the exterior filter to generate the
slot-like gap 3.9.
With the two alternatives of the interior filter 3.2 that can be raised or lifted off, Figure 7 shows
another alternative embodiment, in which a lowerable intermediate bottom is provided in the filter
dome 1.1 above the filters 3 or exterior filters 3.1.

List of Reference Numbers
1 Filter arrangement
1.1 Filter dome
2 Process container
2.1 Bottom
2.2 Cone
3, 3' Filter units
3.1 Exterior filter
3.2 Interior filter

3.3.1 Actuating rod, drive rod
3.3.2 Drive

3.4 Annular region
3.5 Intermediate space
3.6 Outlet region, exhaust air space
3.7 Flap
3.8 Exhaust gas duct
3.9 Annular gap
4 Cleaning device
4.1 Fluid feed line
4.2 Lance

5.1 Cleaning lance
5.2 Outlet
6 Straight-jet nozzle cleaner
6.1 Liquid feed
6.2 Lance

6.3 Discharge nozzle
7 Ultrasound transducer
8 (CIP) liquid

WE CLAIM

1. Filter arrangement for cleaning gases contaminated with particles, with at least one filter
unit (3) with an exterior filter and an interior filter (3.1, 3.2), characterized in that the
exterior and interior filters (3.1, 3.2) can be moved relative to one another while exposing a
gap in the lower region thereof.
2. Arrangement in accordance with claim 1, characterized in that the exterior and interior
filters (3.1, 3.2) can be moved relative to one another while exposing an annular gap (3.9).
3. Arrangement in accordance with claim 1 or 2, characterized in that the interior filter (3.2)
can be raised relative to the exterior filter (3.1).
4. Arrangement in accordance with claim 1 or 2, characterized in that the interior filter (3.2)
can be lowered relative to the exterior filter (3.1).
5. Arrangement in accordance with one of the claims 1 through 4, characterized in that a drive
is provided outside the filter unit (3) for the relative motion between the exterior and interior
filters (3.1, 3.2).
6. Arrangement in accordance with one of the above claims, characterized by a means (4, 4.1,
4.2) for blowing in fluid, especially gas, into the region (3.5, 3.6) of the filter unit (3) on the
clean gas side and by a means (3.7) for closing the region (3.5, 3.6) of the filter unit (3) on
the clean space side against an outlet (3.8).

7. Arrangement in accordance with one of the above claims, characterized by a liquid line
leading into the region (3.5, 3.6) of the filter unit (3) on the clean space side.
8. Arrangement in accordance with claim 7, characterized by a lance or spray head (5.1, 5.2)
protruding into the region (3.5, 3.6) of the filter unit on the clean space side for spraying
cleaning liquid into said region of the filter unit (3).
9. Arrangement in accordance with one of the above claims, characterized by an ultrasound
transducer (7) protruding into an intermediate space between the exterior and interior filters
(3.1, 3.2) for the ultrasonic cleaning of the filters (3.1, 3.2).
10. Arrangement in accordance with one of the above claims, characterized by a cleaning lance
(5.2) protruding into the exterior space of the at least one filter unit (3), which said exterior
space faces away from the clean gas side (3.5, 3.6), especially into a filter dome (1.1)
surrounding same [said filter unit (3)], for cleaning the sides of the filter unit (3) exposed to
the gas contaminated with particles by means of a liquid.
11. Process for cleaning at least one filter unit (3) with an exterior filter (3.1) and with an
interior filter (3.2) of a filter arrangement, which said interior filter is located in said exterior
filter, characterized in that the region (3.5, 3.6) of the filter unit (3) on the clean gas side is
cleaned [by means of] a cleaning fluid sprayed while a gap is exposed in the lower region of
the exterior and interior filters (3.1, 3.2).
12. Process in accordance with claim 11, characterized in that cleaning gas is blown into the
filter unit (3.5 [sic - Tr.Ed.]) and against the direction of flow preferably in advance, while
closing a gas outlet (3.8) from the region (3.5, 3.6) of the filter unit (3) on the clean space

side during the cleaning operation of said filter unit through the filters (3.1, 3.2) of said filter
unit.
13. Process in accordance with claim 11 or 12, characterized in that metal filters of the filter
unit (3) are cleaned by means of an ultrasound lance protruding into the intermediate space
while introducing a coupling liquid into the intermediate space between the exterior and
interior filters (3.1, 3.2) with the gap (3.9) between the two filters (3.1, 3.2) closed.
14. Process in accordance with one of the claims 11 through 13, characterized in that regions of
the filter facing away from the clean gas space (3.5, 3.6) are cleaned by means of a cleaning
liquid ejected from a cleaning lance.
15. Process in accordance with one of the claims 11 through 14, characterized in that drying of
the at least one filter unit (3) is carried out while opening the gap between the exterior and
interior filters (3.1, 3.2).
16. Process in accordance with one of the claims 11 through 15, characterized in that the gap in
the lower region between the external and internal filters (3.1, 3.2) of the at least one filter
unit (3) is opened by lowering or raising the interior filter (3.2) in relation to the exterior
filter (3.1) and closed by an opposite motion.

In order to improve a cleaning of filter units of a
filter arrangement of a process container provided for
the treatment of a product at the site of the filter
units without disassembly of the same (cleaning in
place - CIP), the invention provides a filter
arrangement for cleaning gases contaminated with
particles, having at least one filter unit comprising
an exterior and an interior filter (3.1, 3.2), wherein
the exterior and interior filters can be moved relative
to each other, thereby exposing an opening (3.4) in the
bottom regions thereof. A method for cleaning according
to the invention is further characterized in that the
region of the filter unit on the clean gas side is
cleaned by cleaning fluid sprayed by means of a
cleaning lance protruding into the clean gas region
while exposing a gap (3.4) in the bottom region of the
exterior and interior filters.

Documents:

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Patent Number

279336

Indian Patent Application Number

832/KOLNP/2010

PG Journal Number

03/2017

Publication Date

20-Jan-2017

Grant Date

18-Jan-2017

Date of Filing

04-Mar-2010

Name of Patentee

HÜTTLIN GMBH

Applicant Address

HOHE-FLUM-STRASSE 42 79650 SCHOPFHEIM GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	GROSS, MARTIN	IN DER HAAGMATT 7, 79585 STEINEN GERMANY
2	KNÖLL, MARCUS	RAIFFEISENSTRASSE 3, 79539 LÖRREACH GERMANY
3	SCHMIDT, UWE	HEGNESTRASSE 2E, 79650 SCHOPFHEIM GERMANY
4	MACHO, CHRISTOPH	FRÖBELWEG 15, 79585 STEINEN GERMANY

PCT International Classification Number

B01D 46/00

PCT International Application Number

PCT/EP2008/007170

PCT International Filing date

2008-09-03

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2007 041733.2	2007-09-04	Germany