DE29613098U1 - Filter device - Google Patents

Description

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The present invention relates to a filter device with at least one gas-permeable filter unit through which a raw gas to be cleaned can flow in order to filter out particles, and with a cleaning device which comprises at least one supply line for cleaning gas leading into a clean gas chamber arranged downstream of the filter unit and an associated control unit for temporarily generating a cleaning gas flow through the filter unit that is opposite to the raw gas flow.

Such a filter device is used, for example, to separate dust from the exhaust gases of a crematorium oven. The filter units used must be very heat-resistant, as process temperatures of 1000 ^° C can be reached. Depending on the load of the exhaust gases with dust-like particles that are separated by the filter units, cleaning by generating opposing cleaning flows in the filter units is necessary.

A filter device with the features mentioned above is known from the catalog "NGK CERALLEC SYSTEM (cleaning apparatus for hot gases)" from the company NGK INSULATORS, LTD., Nagoya, Japan. In this device, several prism-shaped filter elements with a vertical longitudinal axis are arranged in a common housing. The raw gas to be cleaned flows through the filter elements from bottom to top. A cleaning device arranged above the filter elements comprises, for example, two horizontally running pipes with gas outlet openings arranged on the underside, through which pressurized cleaning gas can be fed to the filter elements on the clean gas side from above in order to generate an opposite gas flow in the filter elements to clean separated dust particles, which are then discharged downwards into a collecting container.

The disadvantage of the known filter device is that only relatively uneven cleaning can be achieved in the many flow channels running parallel within a filter element. A further disadvantage is that a relatively large amount of cleaning gas is required for each cleaning.

Gesthuysen & von Rohr

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The present invention is based on the object of developing a filter device with the features mentioned at the outset in such a way that particularly efficient cleaning is made possible and that, preferably during cleaning, further filtration of raw gas can be carried out.

A filter device according to the invention with the features mentioned at the outset is characterized in that the cleaning device in the clean gas chamber comprises guide elements connected to the filter unit for increasing and/or equalizing the cleaning gas pressure acting on the filter unit during cleaning.

This significantly increases the efficiency of the cleaning process, so that significantly improved cleaning can be achieved with the same amount of cleaning gas.

In particular, it is provided that the guide elements essentially peripherally surround a front side of the filter unit facing the clean gas chamber and extend away from it. This measure ensures that a cleaning gas jet directed at the front side of the filter unit is optimally guided to the filter unit, whereby a largely uniform pressure profile is established over the entire front surface of the filter unit running transversely to the flow direction, so that the filter unit is cleaned evenly across the entire cross section.

A further development is characterized by the fact that the guide elements largely separate a space directly adjacent to the filter unit from the clean gas space. This means that, especially with several filter units arranged next to one another, they can be cleaned individually with appropriately designed supply lines, whereby the other filter units are largely prevented from influencing the flow of raw gas. Furthermore, the small, demarcated space compared to the clean gas space means that relatively small amounts of cleaning gas have to be supplied in order to achieve a high pressure in the demarcated space and thus effective cleaning, so that very efficient cleaning is achieved.

Gesthuysen & von Rohr

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In a preferred embodiment, the guide elements for delimiting the spatial area comprise side elements directly adjacent to the filter unit and a head surface element preferably arranged parallel to the filter element and at a distance. This design is structurally very simple, since the side elements can, for example, separate the spatial areas of adjacent filter units from one another and the head surface elements for several adjacent spatial areas can be formed by a common plate.

In this case, the guide elements are provided with a passage from the room area into the clean gas space, with the passage preferably being formed in the head surface element. This means that the raw gas flowing through the filter unit during normal operation is relatively little obstructed by the guide elements.

A further embodiment now provides that cleaning gas can be supplied to the room area via the supply line, with at least one outlet of the supply line for cleaning gas opening out close to or in the room area. This enables particularly high cleaning efficiency with minimal influence on the filtration in neighboring filter units.

A particularly preferred variant of the design provides that the passage concentrically surrounds the supply line and that the supply line and its outlet essentially end in the plane of the passage, whereby the passage preferably has an edge that is drawn in towards the area of the space. This design ensures that the annular gap between the supply line and the edge of the passage through which the cleaned raw gas flows during normal operation is practically blocked off during cleaning by the cleaning gas emerging from the outlet and expanding in the process, so that an outflow of cleaning gas into the clean gas space during cleaning is largely prevented.

An alternative embodiment is characterized in that the passage a Laval-like flow tube and the supply line comprises an inner line section and a coaxial outer line section surrounding the inner line section, the line sections forming two concentric, axially offset outlets of the supply line, the inner line section with radial

Gesthuysen & von Rohr

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Distance through the flow pipe into the room area and the outer line section ends in the area of the end of the flow pipe facing away from the room area. When the supply of cleaning gas is switched off, the cleaned raw gas that has flowed through the filter unit from the adjacent room area can flow almost unhindered into the clean gas room through the annular space formed between the line sections of the supply line and the flow pipe of the passage. During cleaning, the cleaning gas is supplied at a relatively high pressure. A relatively small amount of gas emerging from the outer outlet is then sufficient to generate a blocking flow in the flow pipe tapered in a middle area, which interrupts the gas connection between the room area and the clean gas room in the annular space between the inner line section and the flow pipe, so that the cleaning gas supplied to the room area can build up a high pressure there very quickly and leads to effective cleaning of the filter unit.

In order to achieve a highly uniform cleaning of all flow channels, which are usually evenly distributed over the cross-section of the filter unit, it is preferably provided that a distribution element for expanding the cleaning gas flow is arranged downstream of an outlet of the supply line.

In an embodiment that is relatively easy to manufacture, the distribution element is designed in the form of a perforated plate that extends essentially transversely to the outflow direction.

In an alternative embodiment, the distribution element is essentially designed as a shell of a pyramid or a cone with many openings, with the tip pointing in or against the outflow direction of the cleaning gas. Here, too, the distribution element serves to achieve a pressure profile that is as uniform as possible across the front surface of the filter unit, especially in the case of short-term pressure gas surges.

A further embodiment provides that the distribution element is a spherical, outlet head connected to the supply line with a plurality of openings preferably distributed on the hemisphere facing the filter unit

Gesthuysen & von Rohr

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Depending on the distribution of the openings, a uniform outflow and direction of cleaning gas flows onto the filter unit can be achieved.

In order to completely exclude any influence on neighboring filter units when cleaning a filter unit and to achieve optimal efficiency during cleaning, a particularly preferred embodiment provides that the cleaning device includes a valve for closing the passage during cleaning.

In a first variant, the valve is designed so that it closes automatically above a certain relative pressure between the room area and the clean gas area. This results in a very simple construction if, for example, the valve closes the passage arranged in the head surface element during cleaning due to the resulting pressure in the room area separated from the clean gas area, which is significantly higher than during normal operation, while cleaning gas is fed into the room under relatively high pressure through the supply line, which is led laterally or through the head surface element, for example.

In another alternative, the valve is designed so that it can be operated by the control unit. For example, this can be achieved by the valve being pneumatically or electrically controlled by the control device and automatically closed during each cleaning process.

A further alternative is characterized by the fact that the valve is designed and coupled to a supply line or an additional line for cleaning gas in such a way that it is closed when cleaning gas is supplied. In a first variant, this is achieved in that the valve is formed by a nozzle of the line that can be moved longitudinally against spring force due to the cleaning gas pressure, so that when cleaning gas is present, the passage can be closed in a substantially gas-tight manner, the nozzle preferably having a substantially conical end piece at the free end and the passage having a pipe section adapted to the end piece. A second variant provides that the passage concentrically surrounds the supply line and the valve has a concentrically surrounding the supply line.

Gesthuysen & von Rohr

The valve plate is guided axially by the supply line and can be moved to close the passage by cleaning gas flows hitting the valve plate on the side facing away from the passage. In any case, the passage is automatically closed by the valve without any additional control effort when cleaning gas is supplied. The task of the control unit is therefore limited to supplying cleaning gas through the appropriate supply lines when required.

The structure of a filter unit has not yet been discussed in detail. This comprises at least part of an individual filter element, whereby the filter element is preferably essentially prism-shaped with several longitudinal channels, which are alternately closed on one side at their front sides and separated from each other at least by gas-permeable longitudinal walls. Such a filter element is very compact, so that a relatively large filter surface is provided with little space required, thus enabling a high throughput of raw gas to be filtered.

The filter element is preferably made of a ceramic material. This allows excellent heat resistance with relatively good porosity, i.e. relatively low flow resistance, to be achieved.

Preferably, the filter element is installed in the filter device with its longitudinal axis running essentially horizontally, although an oblique or vertical orientation is also possible.

In a particularly preferred embodiment, a filter unit comprises several filter elements of the aforementioned type arranged next to one another and is designed as a replaceable unit. By combining several filter elements into one filter unit, the structural effort for the cleaning device is relatively low and, if necessary, the filter elements can be changed very quickly.

Gesthuysen & von Rohr

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In order to ensure an optimal effect of the guide elements during cleaning, the filter elements preferably end in a common front surface plane, at least on the clean gas side.

The object mentioned at the beginning is also achieved, in particular taking into account the embodiments described above, by a filter device with several gas-permeable filter units arranged next to one another, through which a raw gas to be cleaned can flow in order to filter out particles, and with a cleaning device which comprises several supply lines for cleaning gas leading into a common clean gas chamber arranged downstream of the filter units and an associated control unit for temporarily generating a cleaning flow through the filter units that is opposite to the raw gas flow, whereby the cleaning device is designed in such a way that cleaning gas can be supplied to individual filter units independently of other ones for cleaning. Sequential cleaning or cleaning of only one filter unit can thus take place, so that, in particular, when the embodiments described above are implemented, an adverse effect on the other filter units filtering the raw gas is excluded.

The control unit is preferably designed in such a way that all filter units can be cleaned automatically one after the other after a specified operating time. This reliably prevents excessive clogging of the dust particles from the filter surface separating the raw gas.

Alternatively or additionally, it can be provided that pressure sensors connected to the control unit are arranged before and after the filter units, so that the filter units can be cleaned automatically one after the other depending on the pressure difference between the raw gas side and the clean gas chamber. In this way, especially in the case of heavily dust-laden raw gas, clogging of the filter unit by separated dust can be detected due to the increasing pressure difference and prevented by timely cleaning.

Another variant is characterized by the fact that each filter unit is followed by a separate room area from the clean gas room and in each room area a

Gesthuysen & von Rohr . - 8 -

Sensor for detecting the flow rate, volume or mass flow is provided and the control unit is designed so that the filter elements can be cleaned depending on the sensor values. These sensors allow the individual detection of the contamination levels of the filter units, so that only the filter units that are actually dirty need to be cleaned. For example, to detect the degree of contamination of individual filter units, the deviation of the individual sensor values from an average of all sensor values can be determined. Of course, a combination with differential pressure-dependent and time-controlled cleaning is also possible.

The invention is explained in more detail below using the drawings of several embodiments, whereby the same reference numerals are generally used for identical or similar parts. They show:

Fig. 1 is a sectional view of a proposed filter device with

several filter units and a cleaning device according to a first embodiment,

Fig. 2 a sectional view of a filter unit with cleaning device

according to Fig. 1 when filtering a raw gas to be cleaned,

Fig. 3 a partial sectional view of the filter unit with cleaning device according to Fig. 2, but during cleaning,

Fig. 4 is a sectional view of a filter unit corresponding to Fig. 3 with a

Cleaning device according to a second embodiment,

Fig. 5 is a sectional view of a filter unit corresponding to Fig. 3 with a

Cleaning device according to a third embodiment,

Fig. 6 is a sectional view of a filter unit corresponding to Fig. 3 with a

Cleaning device according to a fourth embodiment,

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Gesthuysen & von Rohr . - 9 -

Fig. 7 is a sectional view of a filter unit corresponding to Fig. 3 with a

Cleaning device according to a fifth embodiment,

Fig. 8 is a sectional view corresponding to Fig. 3 of a filter unit with a

Cleaning device according to a sixth embodiment,

Fig. 9 is a sectional view of a cleaning device according to a seventh embodiment,

Fig. 10 is a sectional view corresponding to Fig. 3 of a filter unit with a cleaning device according to an eighth embodiment, and

Fig. 11 is a sectional view of a cleaning device according to a ninth embodiment.

The filter device 10 shown in Fig. 1 has a housing 12 into which, for example, twelve filter units 14, of which three can be seen in the sectional view, are installed. In the embodiment shown, the filter units 14 are arranged next to one another and one above the other with horizontally running longitudinal axes.

The housing 12 here has an inlet 16 arranged on the top, through which raw gas to be cleaned, for example the exhaust gas from a crematorium oven, can be fed to the filter device 12. The inlet 16 is followed by a raw gas chamber 18 formed in the housing 12, which serves to supply the filter units 14 with raw gas to be cleaned. In the example shown, guide plates 20 are arranged in the raw gas chamber 18 in order to divert the raw gas flow, which in this embodiment flows essentially in a vertical direction from top to bottom through the inlet 16, to the filter units 14 ending in a common vertical surface in the raw gas chamber 18 and, if necessary, to separate larger particles from the raw gas flow. Of course, if required, a different raw gas supply with, for example, an essentially horizontal raw gas flow can be provided.

Gesthuysen & von Rohr

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The raw gas chamber 18 tapers at its lower side to form an empty container 22 for receiving particles filtered out of the raw gas, such as dust.

In the example shown in Fig. 1, the raw gas flows through the filter units 14 essentially from right to left. The structure of the filter units 14 will be discussed in more detail later.

Downstream of the filter units 14, a cleaning device 24 is connected, which has supply lines 28 for supplying a cleaning gas and a control unit 30 associated with it into a clean gas chamber 26 formed by the housing 12 and receiving the cleaned raw gas emerging from the filter units 14. The clean gas collected from the clean gas chamber 26, i.e. filtered raw gas, is discharged via an outlet opening 32 connected to the clean gas chamber 26, for example, into a chimney or other cleaning stages, such as catalytic filters. The arrows not shown in Fig. 1 and 2 illustrate the flow of raw gas through the filter device 10.

The cleaning device 24 has guide elements 34 arranged in the clean gas chamber 26, which are connected to the filter units 14. From the enlarged illustration of a filter unit 14 with a cleaning device 24 connected thereto, according to Fig. 2, it can be seen that the guide elements 34 are directly connected to an end face 36 of the respective filter unit 14 facing the clean gas chamber 26, the guide elements 34 preferably enclosing the end face 36 of each filter unit 40 on all sides and essentially separating a space area 38 from the clean gas chamber 26.

In the preferred and illustrated embodiment, the front side 36 of each filter unit 14 facing the clean gas chamber 26 is essentially square, so that each front side 36 is surrounded by four side elements 40 of the guide elements 34 that are directly adjacent to the filter unit 14, and the corresponding space area 38 is delimited by a head surface element 42 as a further guide element 34, which is arranged at a distance from the front side 36 and is preferably carried by the side elements 34.

Gesthuysen & von Rohr

So that the cleaned raw gas can exit from the demarcated space 38 into the clean gas space 26, the guide elements 34 have at least one passage 44 to the clean gas space 26 for each space 38. In the example shown, the passage 44 is formed in the head surface element 42 in the form of a through opening arranged centrally, i.e. in the middle with respect to the front side 36 of the associated filter unit 14. The raw gas can therefore flow through the filter unit 14 and the adjoining space 38 according to the unmarked arrows in Fig. 2 and then flow through the passage 44 into the clean gas space 26.

Fig. 1 shows that in the example shown, cleaning gas can be supplied to each room area 38 by means of a supply line 28 from the control unit 30. The supply lines 28 with their outlets 46 preferably end in the associated room area 38 or in its vicinity.

The sectional view according to Fig. 3 illustrates the design of the cleaning device 24 according to the first embodiment. Here, each supply line 28 ends with its outlet 46 essentially in the plane of the passage 44, whereby the passage 44 concentrically surrounds the supply line 28 or the outlet 46. In particular, the edge 48 of the head surface element 42 delimiting the passage 44 is drawn in towards the spatial area 38, so that the cross-sectional area of the passage 44 tapers from the side of the head surface element 42 facing away from the spatial area 38 to the free edge of the edge 48. Furthermore, the supply line 28 ends with its outlet 46 approximately in the plane of the head surface element 42. This achieves a nozzle effect such that cleaning gas supplied under high pressure through the supply line 28 expands when it exits the outlet 46 and blocks the passage 44 due to the flow directed essentially towards the front side 36 of the filter unit 14. In this way, in the space area 38, which has a much smaller volume than the clean gas space 26, a high cleaning gas pressure and accordingly a relatively strong cleaning gas flow in the filter unit 14 that is opposite to the raw gas flow are generated very quickly. Furthermore, this blocking effect means that even with a very short, pulse-like supply of cleaning gas into the space area 38, no pressure wave is generated that is opposite to the raw gas flow in the other filter units, so the parallel filtering of raw gas is not hindered.

Gesthuysen & von Rohr

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The supply of cleaning gas through the supply line 28 into the clean gas chamber 38 thus causes a cleaning gas flow in the associated filter unit 14 that is directed against the flow of the raw gas, which leads to the discharge of the particles separated during the filtering of raw gas in the filter unit 14, such as dust, into the raw gas chamber 18, where these particles then sink between the guide plates 20 into the container 22 and are collected there. This container 22 is emptied depending on the fill level, possibly automatically.

In order to achieve the most uniform possible pressure profile of the cleaning gas across the cross section of the filter unit .14, i.e. across the front side 36 in the spatial area 38, a distribution element, in particular according to one of the embodiments described below with reference to Figures 4 to 7, can be arranged downstream of the outlet 46.

In the second embodiment of the cleaning device 24 according to Fig. 4, an essentially flat perforated plate 50 is arranged downstream of the outlet 46 of the supply line 28 as a distribution element, which is aligned at a distance essentially parallel to the front side 36 of the filter unit 14, i.e. here runs essentially transversely to the outflow direction of the cleaning gas flowing out of the outlet 46. In the example shown, the perforated plate 50 is held by holding sections 52 which adjoin the edge 48 of the head surface element 42 and extend towards the front side 36. The arrows not designated indicate the flow path during cleaning, i.e. the supply of cleaning gas.

In the third embodiment of the cleaning device 24 shown in Fig. 5, corresponding to the embodiment shown in Fig. 4, a distribution element arranged downstream of the outlet 46 is held by the holding sections 52. This is essentially designed as a jacket 56 with many openings 54 of a cone or a four-sided pyramid, in particular in accordance with the shape of the front side 36. In the third embodiment, the jacket 56 points with its tip 58 towards the outlet 46 of the supply line 28. Preferably, the opening angle is chosen to be relatively large and is, for example, 90°.

Gesthuysen & von Rohr " . - 13

or more depending on the ratio of the cross-sectional area of the outlet 46 to the front face 36 and the distance between the two latter.

The fourth embodiment shown in Fig. 6 differs from the third embodiment shown in Fig. 5 only in that the tip 58 of the casing 56 is directed in the outflow direction of the cleaning gas, i.e. towards the filter unit 14 or the front side 36.

Fig. 7 shows a fifth embodiment of the cleaning device 24, in which the distribution element is formed by an outflow head 60 connected to the supply line 28 or its outlet 46. In particular, the supply line 28 carrying the outflow head 60 extends into the spatial area 38 in this embodiment. The hollow outflow head 60 is preferably spherical and has a large number of openings (not specified in more detail) on its hemispherical side facing the front side 36 or the filter unit 14, through which the cleaning gas supplied can flow out into the spatial area 38, depending on the density and size of the openings, directed towards the front side 36.

Fig. 8 shows a sixth embodiment of the cleaning device 24, whereby the supply of cleaning gas does not take place through the top surface element 42 or the passage 44 formed in the top surface element 42, but from the side. For this purpose, the supply line 28 passes through a side element 40 of the guide elements 34 in order to end with its outlet 46 directly in the clean gas chamber 38. Even with this outflow direction of the cleaning gas from the outlet 46, which runs essentially parallel to the front side 36 of the filter unit 14, a relatively uniform pressure profile of the cleaning gas across the front side 36 is achieved during cleaning. Advantageously, the passage 44 in this embodiment could also be closed by a valve (not shown here) in order to hermetically seal the space area 38 from the adjoining clean gas chamber 26 during cleaning, i.e. when cleaning gas is supplied through the supply line 28. The valve can be operated pneumatically or electrically, for example, by the control unit 30 that controls the cleaning. Alternatively, the valve can also be designed so that it automatically closes above a certain flow rate or above a pressure drop occurring at the valve.

Gesthuysen & von Rohr ** -*14-

closes so that the valve closes automatically when cleaning gas is supplied. A further advantage of this automatically closing valve design is that even if a filter unit 14 fails, i.e. if it breaks, a significantly increasing flow of raw gas would lead to the valve closing and thus the flow of uncleaned raw gas would be prevented.

A seventh embodiment of the cleaning device 24 is shown in detail in Fig. 9. In this case, the supply line 28 is essentially modified in the area of its outlet 46 compared to the first embodiment according to Figures 1 to 3 in such a way that a type of Laval nozzle is formed. For this purpose, the passage 44 formed in the head surface element 42 is delimited by a flow tube 62 carried by the head surface element 42, which is designed in the shape of a lavai, which means that the flow tube 62 tapers steadily in its clear cross section from its two ends towards the middle.

The supply line 28 extends into the aforementioned flow tube 62 with an inner line section 64 and an outer line section 66 surrounding it. The respective tubular line sections 64 and 66 are arranged coaxially to one another, with the outer line section 66 ending in the first axial half of the flow tube 62 and the inner line section 64 extending further into at least the second half of the flow tube 62 or even through it into the space area 38 and ending there in an outlet 68. The annular gap between the inner line section 64 and the end of the outer line section 66 forms a second, outer outlet 70 of the supply line 28.

In normal operation, i.e. when filtering raw gas, the cleaned raw gas leaves the space area 38 through the annular space of the passage 44, which is defined due to the radial distance of the flow pipe 62 to the line sections 64, 66, in order to reach the clean gas space 26.

During cleaning, cleaning gas is supplied through the supply line 28, which exits both at the outlet 68 and at the outlet 70. The gas exiting at the outer outlet 70

Gesthuysen & von Rohr ** "-15

The cleaning gas that enters the chamber 38 generates a relatively strong flow in the flow cross-section between the inner line section 64 and the flow pipe 62, which narrows towards the middle of the flow pipe 62, which prevents gas from escaping from the chamber 38 through this annular space into the clean gas chamber 26. This blocking effect means that even with a relatively small amount of cleaning gas in the chamber 38, a high pressure can be generated during cleaning, with the result that the subsequent filter unit 14 is effectively cleaned in a short time.

A further advantage of the embodiment shown in Fig. 9 is that the gas jet emerging from the outer outlet 70 is fanned out during cleaning by the end of the flow tube 62 facing the spatial area 38 and widening in cross-section, so that together with the gas jet emerging from the outlet 68 a very uniform pressure distribution of the cleaning gas during cleaning over the front side 36 of the associated filter unit 14 and thus a uniform cleaning of the filter unit 14 is achieved.

A further advantage of the above-mentioned arrangement is that the gas flow emerging from the outer outlet 70 during cleaning can entrain gas from the clean gas chamber 26 and convey it into the chamber area 38, so that an optimal cleaning of the subsequent filter unit 14 can be achieved with relatively small amounts of cleaning gas to be supplied.

An eighth embodiment of the cleaning device 24 is explained in more detail below with reference to Fig. 10, whereby again for reasons of simplification only one supply line 28 with an associated filter unit 14 is shown. This embodiment largely corresponds to the embodiment shown in Fig. 5. In addition, a valve 72 is provided which is closed during the cleaning, i.e. during the supply of cleaning gas through the supply line 28, in order to prevent cleaning gas from escaping from the space area 38 into the space area 26 with a view to efficient cleaning.

Gesthuysen & von Rohr ". " -*16-

The valve 72 is formed here by a valve plate 74 which concentrically surrounds the supply line 28, which is guided axially displaceably on the supply line 28 and is designed in such a way that it can close or cover the passage 44 or the annular space formed between the supply line 28 and the head surface element 42. To actuate the valve plate 74, the supply line 28 has secondary branches 76 which are designed and arranged in such a way that when cleaning gas is supplied through the supply line 28, a small part of the cleaning gas flow is directed directly onto the valve plate, namely on the side facing away from the passage 44. The cleaning gas flows emerging from the secondary branches 76 during cleaning cause the valve disk 74 to be displaced towards the passage 44 and closes it, so that the cleaning gas flowing out of the outlet 46 of the supply line 28 effects efficient cleaning of the downstream filter unit 14.

After cleaning is complete, the valve disk 74 is moved away from the passage 44 again by the gas pressure building up in the space area 38, whereby the passage 44 is released again.

Of course, the valve arrangement described above can also be used in combination with another embodiment described above.

The ninth embodiment of the cleaning device 24 shown in Fig. 11 also includes a valve 72 or a valve-like arrangement in order to at least largely interrupt the passage 44 from the space area 38 to the clean gas space 26 during cleaning. For the sake of simplicity, in Fig. 11, analogous to Fig. 9, only part of a head surface element 42 is shown, but two supply lines 28 lead through the head surface element 42 directly into the space area 38 and end there with their outlets 46.

In this embodiment, an additional line 88, which can be supplied with cleaning gas from the control unit 30, is guided near the passage 44, which has a tubular nozzle 78 on its free end that can be moved longitudinally. This nozzle 78 has a free end, which is connected to the head surface element 42 or

Gesthuysen & von Rohr " -17-

whose end facing the passage 44 has an end piece 80 which, in the example shown, is hollow conical, with the tip 82 of the end piece 80 pointing towards the passage 44. The nozzle 78 can be displaced towards the passage 44 against the force of a spring 84 which here surrounds the line 88 and is preferably spiral-shaped, due to the cleaning gas pressure acting on the end piece 80 during cleaning.

The passage 44 provided in the head surface element 42 is designed in such a way that the nozzle 78, which is displaced to the passage 44 during cleaning, creates a largely gas-tight seal of the passage 44. For this purpose, in the example shown, the passage 44 is delimited by a pipe section 86 carried by the head surface element 42, which is adapted to the end piece 80 of the displaceable nozzle 78 and points towards it with its longitudinal axis.

The nozzle 78, which can be moved longitudinally during cleaning by the cleaning gas, with its end piece 80 and the pipe section 86 form the valve 72 in this embodiment. During normal filtering of raw gas, the nozzle 78 with its end piece 80 is moved away from the pipe section 86 due to the force of the spring 84, so that filtered raw gas can escape unhindered from the space area 38 through the pipe section 86 past the end piece 80 into the clean gas space 26. During cleaning, the nozzle 78 is displaced against the spring force towards the pipe section 86 due to the cleaning gas pressure acting on the inside of the end piece 80 in such a way that the end piece 80, which then at least partially protrudes into the facing end of the pipe section 86, causes the passage 44 to be sealed at least largely gas-tight, so that the nozzle 78 is in the position shown in dashed lines in Fig. 11. The passage 44 is thus closed for gas flowing from the space area 38 into the clean gas space 26 during cleaning.

In the embodiment shown in Fig. 11, the cleaning device 24 comprises an additional line 88 per filter unit 14, which can branch off from the supply lines 28 or be led directly to the control unit 30.

Gesthuysen & von Rohr * -18-

By using two supply lines 28 per filter unit 14, a particularly even distribution of the cleaning gas in the spatial area 38 over the front surface 36 and, in particular, a particularly good exposure of the edge areas of the filter unit 14 with cleaning gas is achieved.

Of course, the multiple supply lines 28 per filter unit 14 explained in connection with Fig. 11 can also be combined with the other aforementioned embodiments of the cleaning device 24.

The filter units 14 are each preferably composed of several filter elements, as are known, for example, from the catalog mentioned at the beginning. These filter elements are preferably prism-shaped with an essentially square base. Each filter element has a large number of flow channels running parallel to one another in its longitudinal direction, which are alternately closed at one end. Raw gas entering an open flow channel on one end of the filter element must diffuse through the side wall delimiting the flow channel into an adjacent flow channel in order to then pass through a channel open at the other end to the other end of the filter element and exit there into the clean gas chamber 26 or the adjoining space area 38. When the gas flows through the side walls, particles carried by the raw gas are largely separated. These separated particles clog the side wall over time, so that the flow resistance for the raw gas flowing through the filter element increases with the operating time. The cleaning gas flow through the filter element caused by the cleaning device 24, which is opposite to the raw gas flow, causes the separated dust particles to be released from the side wall again and discharged into the raw gas chamber 18, where they can be collected in the container 22 of the filter device 10 and disposed of.

It has now proven to be particularly advantageous to combine several of these filter elements into a filter unit 14. For example, four filter elements, i.e. two next to each other and two on top of each other, are held as a filter unit 14 by a common frame, preferably a metal frame. In order to compensate for thermal expansion and to prevent damage to the filter elements

Gesthuysen & von Rohr **** *" V -19-

In order to avoid this, they are preferably covered with heat-resistant fabric stockings and padded with inflatable mats or similar in relation to each other and to the metal frame.

Such a filter unit 14 then forms a structural unit that can be separately installed and removed from the housing 12 of the filter device 10. This enables the filter elements in the filter device 10 to be replaced very quickly if necessary.

Another important aspect of the proposed filter device 10 is that several filter units 14 are arranged next to one another in a common housing, i.e. the raw gas stream to be cleaned can flow through them in parallel, and that the cleaning device 24 is designed in such a way that the filter units 14 can each be cleaned independently of one another. In this way, individual filter units 14 can be cleaned without interrupting the filtering of raw gas. This avoids, for example, a backflow in an oven connected to the inlet 16 of the filter device 10 during cleaning. It is precisely by providing a space area 38 downstream of each filter unit 14, which is at least largely sealed off from the common clean gas collection space 26, that it is also ensured that when a filter unit 14 is cleaned, for example with strong pressure surges, any influence on the filtering of raw gas taking place simultaneously in the other filter units 14 is largely excluded.

The cleaning is controlled automatically by the control unit 30. For this purpose, the control unit 30 is designed in such a way that the filter units 14 are automatically cleaned one after the other at predeterminable time intervals. For this purpose, the control unit 30 supplies compressed air to the filter units 14 one after the other through the supply lines 28, for example using a compressor (not shown). The length of time during which cleaning gas, such as compressed air, is supplied to the individual filter unit 14 can preferably be preset on the control unit 30 or another control system and is, for example, 0.1 to approximately 2 seconds.

Gesthuysen & von Rohr "** " ** * " -20-

Instead of cleaning the filter units 14 in quick succession after a specifiable time interval, the filter units 14 can also be cleaned evenly over the time interval. In this way, more uniform flow conditions are achieved in the filter device 10 over the time interval.

Furthermore, alternatively or in addition to the aforementioned time-controlled cleaning, differential pressure-dependent cleaning can also be carried out. For this purpose, a pressure sensor 90 is arranged in the raw gas chamber 18 and in the clean gas chamber 26. The measured values of these pressure sensors 90 are evaluated by the control unit 30, and depending on the pressure difference between the raw gas side and the clean gas side, a sequential cleaning of the filter units 14 is effected by the control unit 30, since this differential pressure is a measure of the contamination or clogging of the filter units 14 with the dust particles or other deposits to be filtered out. With this cleaning, which takes place depending on the pressure drop, the response behavior of the control unit 30 can be determined by specifying a pressure value and, if this pressure value is exceeded, a cleaning is triggered by the differential pressure.

In a further alternative, individual cleaning of the individual filter units 14 can be achieved depending on the degree of contamination by arranging a sensor (not shown in the drawings) in the space 38 downstream of each filter unit 14, which sensor delivers a measurement signal that is proportional to the flow of raw gas flowing through the respective filter unit 14, such as the flow rate, the volume flow or the mass flow. Using these sensor values, the control unit 30 can then detect excessive contamination of a filter unit 14 and can remedy this by cleaning it. This design of the cleaning device 24 is particularly suitable when filter devices 10 with a large number of filter units 14 are provided, whereby different separation can occur in the individual filter units 14 due to different flow conditions.

In a further embodiment, the cleaning device 24 comprises a preheating device (not shown) to preheat the cleaning gas to be supplied before it hits the filter elements. This can prevent excessively high temperatures.

Gesthuysen & von Rohr - 21

Temperature differences between the raw gas to be cleaned and the cleaning gas supplied during cleaning, which can lead to the destruction of the filter elements, are avoided. In order to keep the thermal load on the filter elements as low as possible when changing between cleaning and cleaning, a temperature sensor can be provided on the raw gas side and/or the clean gas side to measure the temperature of the raw gas to be cleaned or the already cleaned raw gas. Depending on this raw gas temperature, the control unit 30 can then control the aforementioned preheating device so that the compressed air to be supplied as cleaning gas, for example, is preheated to the measured raw gas temperature. In order to reliably rule out damage to the filter elements due to excessive temperature differences between the gases alternately supplied to the filter elements, a further variant provides that the preheating device can be activated automatically by the control unit 30 when a preset temperature difference between the raw gas temperature and the cleaning gas temperature is exceeded.

Gesthuysen & von Rohr

-22

List of reference symbols:

10 Filter device

12 Housing

14 Filter element

16 Inlet

18 Raw gas room

20 Baffle

22 Container

24 Cleaning device

26 Clean gas room

28 Supply line

3 0 Control unit

32 Outlet opening

34 Guide element

3 6 Front side

3 8 Room area

40 Page Element

42 Head surface element

44 Passage

46 Outlet

48 Edge

50 hole plate

52 Holding section 54 Opening 56 Sheath

58 lace

60 outlet head 62 flow pipe 64 inner pipe section 66 outer pipe section 68 inner outlet 70 outer outlet 72 valve

74 Valve disc 76 Secondary branch 78 Nozzle 80 End piece 82 Tip

84 Spring

86 Pipe section 88 Line 90 Pressure sensor

Claims (1)

Gesthuysen & von Rohr . - 23 - Protection claims : 1. Filter device with at least one gas-permeable filter unit (14) through which a raw gas to be cleaned can flow to filter out particles, and with a cleaning device (24) which comprises at least one supply line (28) for cleaning gas leading into a clean gas chamber (26) downstream of the filter unit (14) and an associated control unit (30) for temporarily generating a cleaning gas flow through the filter unit (14) that is opposite to the raw gas flow, characterized, that the cleaning device (24) in the clean gas chamber (26) comprises guide elements (34) connected to the filter unit (14) for increasing and/or equalizing the cleaning gas pressure acting on the filter unit (14) during cleaning. 2. Filter device according to claim 1, characterized in that the guide elements (34) essentially peripherally delimit an end face (36) of the filter unit (14) facing the clean gas chamber (28) and extend away from it. 3. Filter device according to claim 1 or 2, characterized in that the guide elements (34) at least largely delimit a spatial region (38) directly adjoining the filter unit (14) from the clean gas space (26). 4. Filter device according to claim 3, characterized in that the guide elements (34) for delimiting the spatial area (38) comprise side elements (40) directly adjoining the filter unit (14) and a head surface element (42) arranged essentially parallel to the filter element and at a distance therefrom. 5. Filter device according to claim 3 or 4, characterized in that the guide elements (34) have a passage (44) from the space area (38) into the clean gas space (26). 6. Filter device according to claims 4 and 5, characterized in that the passage (44) is formed in the head surface element (42). Gesthuysen & von Rohr . ■ -2A I. Filter device according to one of claims 3 to 6, characterized in that cleaning gas can be supplied to the space region (38) via the supply line (28). 8. Filter device according to claim 7, characterized in that at least one outlet (46) of the supply line (28) for cleaning gas opens out close to or in the space area (38). 9. Filter device according to claims 5 and 8, characterized in that the passage (44) concentrically surrounds the supply line (28) and that the supply line (28) ends with its outlet (46) essentially in the plane of the passage (44). 10. Filter device according to claim 9, characterized in that the passage (44) has an edge (48) which is drawn in towards the spatial region (38). II. Filter device according to one of claims 5 to 10, characterized in that the passage (44) comprises a Laval-like flow tube (62) and the supply line (28) comprises an inner line section (64) and a coaxial outer line section (66) surrounding the inner line, the line sections (64, 66) forming two concentric, axially offset outlets (68, 70) of the supply line (28), the inner line section (64) extending at a radial distance through the flow tube (62) into the spatial region (38) and the outer line section (66) ending in the region of the end of the flow tube (62) facing away from the spatial region (38). 12. Filter device according to one of the preceding claims, characterized in that a distribution element for expanding the cleaning gas flow is arranged downstream of an outlet (46) of the supply line (28). 13. Filter device according to claim 12, characterized in that the distribution element is a perforated plate (50) extending substantially transversely to the front side (36) of the filter unit (14). 14. Filter device according to claim 12, characterized in that the distribution element is essentially designed as a casing provided with many openings (54) Gesthuysen & von Rohr - 25 - (56) of a pyramid or a cone, wherein the tip (58) points in or against the outflow direction. 15. Filter device according to claim 12, characterized in that the distribution element is a spherical outflow head (60) adjoining the supply line (28) with a plurality of openings preferably distributed on the hemisphere facing the filter unit (14). 16. Filter device according to one of claims 5 to 15, characterized in that the cleaning device (24) comprises a valve (72) for closing the passage (44) during cleaning. 17. Filter device according to claim 16, characterized in that the valve (72) is designed such that it closes automatically when a certain pressure in the space area (38) relative to the clean gas space (26) is exceeded. 18. Filter device according to claim 16, characterized in that the valve (72) is designed such that it can be actuated by the control unit (30). 19. Filter device according to claim 16, characterized in that the valve (72) is designed and coupled to a line (88) for cleaning gas in such a way that it is closed during the supply of cleaning gas. 20. Filter device according to claim 19, characterized in that the valve (72) is formed by a nozzle (78) of the line (88) which can be moved longitudinally against spring force, so that when cleaning gas is present the passage (44) is closed off in a substantially gas-tight manner. 21. Filter device according to claim 20, characterized in that the nozzle (78) has a substantially conical end piece (80) at the free end and the passage (44) has a pipe section (86) adapted to the end piece (80). 22. Filter device according to claim 19, characterized in that the passage (44) concentrically surrounds the supply line (28) and the valve (72) has a supply line Gesthuysen & von Rohr . · - 26 - (28) concentrically surrounding valve plate (74), wherein the valve plate (74) is guided axially displaceably by the supply line (28) and can be displaced by impinging cleaning gas flows to close the passage (44). 23. Filter device according to one of the preceding claims, characterized in that the filter unit (14) comprises at least part of an individual filter element. 24. Filter device according to claim 23, characterized in that the filter element is essentially prism-shaped with several longitudinally extending channels, which are alternately closed on one side at their end faces and are separated from one another at least by gas-permeable longitudinal walls. 25. Filter device according to claim 23 or 24, characterized in that the filter element is made of a ceramic material. 26. Filter device according to one of claims 23 to 25, characterized in that the filter element is installed with its longitudinal axis running essentially horizontally. 27. Filter device according to one of the preceding claims, characterized in that the filter unit (14) comprises several filter elements arranged next to one another. 28. Filter device according to claim 27, characterized in that the filter unit (14) is designed as a replaceable unit. 29. Filter device according to claim 27 or 28, characterized in that the filter elements end in a common end face plane at least on the clean gas side. 30. Filter device with several gas-permeable filter units (14) arranged next to one another, through which a raw gas to be cleaned can flow in order to filter out particles, and with a cleaning device (24) which has several Gesthuysen & von Rohr **** ** " " - 27 a common clean gas chamber (26) downstream of the filter units (14) and having supply lines (28) for cleaning gas and an associated control unit (30) for temporarily generating a cleaning gas flow through the filter units (14) opposite to the raw gas flow, in particular according to one of the preceding claims,
characterized, that the cleaning device (24) is designed such that individual filter units (14) can be supplied with cleaning gas for cleaning independently of other cleaning gases. 31. Filter device according to claim 30, characterized in that the control unit (30) is designed such that all filter units (14) can be automatically cleaned one after the other after a predeterminable operating time. 32. Filter device according to claim 30 or 31, characterized in that pressure sensors (90) connected to the control unit (30) are arranged before and after the filter units (14), so that the filter units (14) can be automatically cleaned one after the other depending on the pressure difference between the raw gas side and the clean gas chamber (26). 33. Filter device according to claim 3 and one of claims 30 to 32, characterized in that a sensor for detecting the flow velocity, the volume or mass flow is provided in each spatial area (38) and the control unit (30) is designed such that the filter elements (14) can be cleaned individually depending on the sensor values.