A filtration device and a filter cassette for such a device

Abstract

The invention concerns a filtration device (1) for removing e.g. oil-based particles from a gas flow, the filtration device (1) comprises: a device housing (2); a plurality of filter units (3, 4, 5, 6) arranged on top of each other inside the device housing (2); a gas flow inlet (7); a gas flow outlet (8), wherein the plurality of filter units (3, 4, 5, 6) comprises a first filter unit (5) provided with a filter element (51) configured to separate e.g. oil-based particles from a gas that flows through the filter element (51), wherein the first filter unit (5) comprises a module frame (52) arranged to be inserted into and removed from the filtration device (1) in a substantially horizontal direction, wherein the module frame (52) is arranged to hold the filter element (51) in an inclined position in relation to a horizontal plane when installed in the filtration device (1) so that oil-based or other liquid trapped in the filter element (51) flows not only downwards but also sideways towards a lower edge (53) of the inclined filter element (51).

Description

[0001] P480653PC00

[0002] 1

[0003] A filtration device and a filter cassette for such a device

[0004] TECHNICAL FIELD

[0005] This invention relates to a filtration device for removing e.g. oil-based particles from a gas flow, such as an exhaust flow from CNC machines. The invention also relates to a filter cassette for such a device.

[0006] BACKGROUND OF THE INVENTION

[0007] Operation of CNC (Computer Numerical Control) machines, such as metal milling cutters, lathes, drills, etc., typically leads to generation of “oil smoke” containing oil-based particles and other substances. Such oil smoke poses a health hazard if inhaled and also causes slippery floors etc. if released uncleaned in a workshop or factory. CNC machines, as well as other machines and processes generating similar smoke, are generally provided with an exhaust system and a filtration device for cleaning the exhaust gas flow.

[0008] WO2021 / 185477 discloses an example of a filtration device for cleaning of oil smoke, oil mist and similar where the device includes a filter adapted to separate oil particles from a flow of gas passing through the filter. The filter is made up of a filter medium that is folded into a layered structure with spacers arranged between adjacent folds / layers.

[0009] A filtration device according to WO2021 / 185477 works well in principle but there is a general demand for improvements.

[0010] SUMMARY OF THE INVENTION

[0011] The invention concerns a filtration device for cleaning of a gas flow, such as for removing e.g. oil-based particles from a gas flow exhausted from a CNC machine, wherein the filtration device comprises: a device housing; a plurality of filter units arranged on top of each other inside the device housing; an inlet for an incoming gas flow arranged in a lower portion of the device housing;and an outlet for an outgoing gas flow arranged in an upper portion of the device housing, wherein the filtration device is configured so that, during operation of the filtration device, the gas to be filtered flows from the inlet upwards through the device housing, and thereby sequentially through the plurality of filter units and further to the outlet.

[0012] The plurality of filter units comprises a first filter unit provided with a filter element configured to separate particles, such as oil-based particles, from a gas that flows through the filter element. The first filter unit comprises a module frame arranged to be inserted into and removed from the filtration device in a substantially horizontal direction and to be oriented in a corresponding substantially horizontal position when installed in the filtration device.

[0013] The first filter unit may be an oil filter unit specially adapted to separate oilbased particles. The plurality of filter units may, for instance, comprise a coarse filter unit at the bottom, a fine filter unit at the top, and an additional (second) oil filter unit arranged below or above the first oil filter unit. However, the first filter unit is not necessarily of oil-type and the plurality of filter units may comprise various combinations of filter elements.

[0014] The term “first” filter unit is not related to e.g. flow order but simply used to distinguish a certain filter unit in the plurality of filter units.

[0015] The module frame is arranged to hold the filter element in an inclined position in relation to a horizontal plane when installed in the filtration device so that at least a lower side of the filter element is inclined in relation to the horizontal plane allowing oil-based or other liquid originating from particles trapped in the filter element to flow not only downwards but also sideways along the inclined lower side towards a lower edge of the inclined filter element.An advantage of a filtration device of the above type is that the oil-based or other (e.g. water-based or mixed) liquid separated from the gas flow has a reduced negative effect on the filter (or other component) located below the first filter unit. With an ordinary, horizontally oriented filter element, the oil or other liquid present in the filter element will, due to the action of gravity, simply flow straight downwards over the entire filter element area and drop down onto, typically, the entire filter area of another filter (or other component or area) located below and thus fully cover that lower filter with oil or other liquid.

[0016] Due to the inclination of the lower side of the filter element, most of the trapped liquid will flow sideways along the inclined underside of the filter element (due to adhesive forces) towards the lower edge thereof and will not drop down onto a filter below until it reaches a region located close to the lower edge, i.e. a region that typically is located close to the edge of a filter located below. The negative contamination effect on the filter below is thus reduced since only a small area of that filter will be subject to dripping liquid (and the negative effect can be reduced further by arranging a drain system below and along the lower edge). This typically extends the time of operation of the device until a filter needs to be exchanged. Even if no filter is arranged below the inclined lower side, it is often an advantage to reduce the area subject to dripping liquid. Also, the amount of oil or other liquid remaining in the filter element of the first filter unit after turning off the device will be less than if the lower side of the filter element is oriented horizontally. This reduces the pressure drop when restarting the device.

[0017] Conventional filter elements of the type of interest here are often box-shaped with flat and parallel upper and lower sides, which means that the lower side of the filter element will be inclined if the entire filter element is arranged in an inclined position. However, if the upper and lower sides are not parallel, the upper side might be horizontally oriented while the lower side is inclined inrelation to the horizontal plane. The lower side of the filter element does not necessarily have to be flat.

[0018] A further advantage of arranging e.g. an oil filter element in an inclined position (or at least so that the lower side thereof is inclined) in a module frame that is to be oriented horizontally is that it becomes possible to combine the advantages of using an inclined oil filter with the advantages of letting the filtration device as a whole extend in a generally vertical direction. In principle, inclined filters may be arranged by inclining the entire housing of a conventional filtration device where the filter units are arranged on top of each other. However, if a straight and relatively high filtration device is inclined it requires a considerably larger floor area because the downwardly projected area increases (and also because a supporting arrangement for preventing the device from falling over may require additional space), and in many workshops and factories the available floor area is limited. In addition, in cases where a fan is arranged in the filtration device, for instance as a fan module at the top of the housing, it is generally an advantage that the filtration device extends vertically to reduce load and asymmetrical forces acting on a drive shaft of the fan.

[0019] Exactly how the oil or other liquid flows sideways along the filter element and exactly how much the lower side of the filter element should be inclined depends for instance on the type and structure of the filter element used. Liquid present on an underside of the filter element typically stick to some degree to the underside due to adhesive forces (within the droplet as well as between the droplet and the surface it is located at). Because of the inclination, that liquid can flow sideways towards the lower edge of the filter element. An additional component may be provided at the underside of the filter element to prevent downwards dripping and enhance sideways flow, such as a relatively wide-meshed net (that does not prevent through-flow of the gas flow).The filter element or the lower side thereof may be inclined at an angle of 5-45°, or 10-30°, or 15-25° in relation to the horizontal plane. The filter element may have the shape of a rectangular cuboid so that the inclination becomes the same for the upper and lower sides thereof. Folded filter elements of the type described in WO2021 / 185477 may be used, but other types are also possible, such as HEPA filters or carbon filters. If the filter element is arranged in a filter frame, such as a wall structure with a flange at the lower side that holds the filter element in place, the filter frame may be arranged in the inclined position in the module frame. The filter element may be oriented in different ways in the horizontal plane so that the lower edge thereof faces a rear wall or front wall (access door) of the housing or any of the side walls.

[0020] If desired, a drain passage may be arranged at the lower edge of the filter element so as to lead the oil or other liquid away from e.g. a filter located below.

[0021] The module frame may be arranged to support an additional filter element, inclined or not, located above or below the inclined filter element described above.

[0022] In a typical application the filtration device is a modular structure comprising a plurality of filter module units arranged on top of each other and where each filter module includes at least one filter element and a module housing that is connected to other module housings so as to together form the device housing. Such a filtration device may contain a combination of one or more oil filter units with inclined (oil) filter elements as well as one or more conventional filter units with non-inclined filter elements, such as a coarse filter located closest to the gas flow inlet and a HEPA filter or other type of fine filter as the last filter in the flow order. Alternatively, a filter unit with an inclined filter element may be arranged e.g. closest to the gas flow inlet, and the inclined filter element may be e.g. a HEPA filter. The gas flow inlet maybe arranged in a bottom module and a fan for generating the gas flow may be arranged in a top module together with the gas flow outlet.

[0023] The device housing is provided with one or more doors to provide an access opening for allowing the module frame to be inserted into and removed from the filtration device and thus to allow exchange of filters (a module frame with a used filter is removed and replaced by a another module frame provided with a fresh filter). A filter device with modular structure typically has one door for each module.

[0024] The filtration device may comprise two filter towers extending vertically side by side within a common device housing, where each filter tower comprises a plurality of filter units arranged on top of each other as described above. In such a case, one single module frame may serve both filter towers and may be provided with an inner and an outer filter element so as to allow for exchanging filter elements in both filter towers by exchanging the single module frame. Separate module frames may, however, be preferred since the filter elements may be heavy and somewhat difficult to handle.

[0025] In an embodiment, the filter element comprises a filter medium folded into a layered structure so as to form a plurality of substantially vertically extending filter medium layers arranged side by side. As noted above, other types of filter medium may be used.

[0026] In an embodiment, the filter element is oriented so that the lower edge of the inclined filter element extends in a direction perpendicular to the filter medium layers. Liquid may then flow along the filter medium layers, between the layers and along the folded edges of the layers, towards the lower edge of the inclined filter element.

[0027] In an embodiment, spacers are arranged between the filter medium layers.In an embodiment, the filter element has the shape of a rectangular cuboid. For instance, a filter medium may be folded into a box-like shape.

[0028] In an embodiment, the filter element is arranged in a filter frame.

[0029] In an embodiment, the filter element is directly or indirectly fastened to the module frame so as to form a filter cassette comprising the module frame and the filter element, and wherein the module frame is removable from the filtration device so as to allow for exchange of the filter element by exchanging the filter cassette.

[0030] In an embodiment, the module frame is provided with a flange that extends circumferentially around the module frame at an upper part thereof. The flange is useful for providing a seal between the module frame and a component in the device housing so as to force the gas to flow the intended way through the filter units. A sealing member may be placed between the flange of the module frame and e.g. another flange arranged in the upper part of the corresponding filter unit, and by pressing the two flanges towards each other, with the sealing member arranged there between, a seal is provided. The filtration device may be provided with a pressing / clamping arrangement for pressing and clamping the module frame in place in a sealed manner. For instance, after having placed the module frame in a proper horizontal position inside the device housing, such a pressing / clamping arrangement can be used to slightly lift the module frame so as to press it upwards and lock / clamp it in place. Such pressing / clamping arrangements for filtration devices are known as such.

[0031] In an embodiment, a sealing member is arranged on an upper side of the flange. Alternatively, the sealing member may be arranged inside the device housing.

[0032] In an embodiment, the flange extends in a horizontal plane.In an embodiment, the module frame has two opposite side walls, a rear wall and an upper front portion that connects the two opposite side walls. Such a module frame is adapted to carry a box-like filter element or filter frame that has its lower edge facing the rear side of the module frame, i.e. the lower edge of the filter element will be facing inwards the device housing when the module frame is installed in the filtration device.

[0033] In an embodiment, the module frame is provided with support members that holds the filter frame in place in an inclined position between the side walls of the module frame.

[0034] In an embodiment, the filtration device comprises one or more additional filter units arranged below and / or above the first filter unit. The one or more additional filter units may comprise one or more of the following:

[0035] - a lower filter unit located below the first filter unit and being provided with a coarse filter element;

[0036] - a second filter unit located below or above the first filter unit wherein the second filter unit is arranged in the same way as the first filter unit; and / or - an upper filter unit located above the first filter unit and being provided with a fine filter element.

[0037] In an embodiment, the plurality of filter units forms modular filter units, each having a module housing that is connectable to another module housing so as to form the device housing when connected.

[0038] The invention also concerns a filter cassette for a filtration device, wherein the filter cassette comprises: a filter element configured to separate particles, such as oil-based particles, from a gas that flows through the filter element; and a module frame arranged to be oriented in a substantially horizontal position when installed in the filtration device, wherein the module frame is arranged to hold the filter element in an inclined position in relation to ahorizontal plane when installed in the filtration device so that at least a lower side of the filter element is inclined in relation to the horizontal plane allowing oil-based or other liquid originating from particles trapped in the filter element to flow not only downwards but also sideways along the inclined lower side towards a lower edge of the inclined filter element.

[0039] In an embodiment, the filter element comprises a filter medium folded into a layered structure so as to form a plurality of filter medium layers arranged side by side, wherein the filter element is arranged so that the filter medium layers extend substantially vertically when the module frame is oriented in the substantially horizontal position.

[0040] In an embodiment, the filter element is oriented so that the lower edge of the inclined filter element extends in a direction perpendicular to the filter medium layers.

[0041] In an embodiment, spacers are arranged between the filter medium layers.

[0042] In an embodiment, the filter element has the shape of a rectangular cuboid, and wherein the first filter element is arranged in a filter frame.

[0043] In an embodiment, the module frame is provided with a flange that extends circumferentially around the module frame at an upper part thereof, wherein the flange extends in a horizontal plane when the module frame is oriented in the substantially horizontal position.

[0044] In an embodiment, a sealing member is arranged on an upper side of the flange.

[0045] In an embodiment, the module frame has two opposite side walls, a rear wall and an upper front portion that is connected to the two opposite side walls.In an embodiment, the module frame is provided with support members that holds the filter frame in place in an inclined position between the side walls with a rear side of the filter frame in contact with the rear wall of the module frame.

[0046] In an embodiment, a lower portion of each of the side walls forms a support surface that extends in a horizontal plane when the module frame is oriented in the substantially horizontal position.

[0047] BRIEF DESCRIPTION OF DRAWINGS

[0048] In the description of the invention given below reference is made to the following figure, in which:

[0049] Figure 1 shows an example of a filtration device according to the present disclosure.

[0050] Figure 2 shows a sectional view of the filtration device of figure 1.

[0051] Figure 3 shows a sectional side view of the filtration device of figure 1.

[0052] Figure 4 shows the filtration device of figure 1 with an access door of a first filter unit removed.

[0053] Figure 5 shows the filtration device of figure 4 with a filter pressing / clamping arrangement released.

[0054] Figure 6 shows the filtration device of figure 4 with a module frame removed. Figures 7a-7d show an example of a filter cassette according to this disclosure and how such a filter cassette may be assembled and dissembled. Figure 8 shows a sectional view of the filter cassette of figure 7a.

[0055] Figures 9a-9c show the structure of an example of a filter element and filter frame.

[0056] DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0057] Figures 1-6 show an example of a filtration device 1 that in this case is adapted for removing e.g. oil-based particles from a gas flow. The filtration device 1 comprises: a generally vertically extending device housing 2; a plurality of, in this case four, filter units 3, 4, 5, 6 arranged on top of eachother inside the device housing 2; an inlet 7 for an incoming gas flow arranged in a lower portion of the device housing 2; and an outlet 8 for an outgoing gas flow arranged in an upper portion of the device housing 2. A fan unit / module 10 with a fan 71 is arranged on top of the filtration device.

[0058] When operating the fan 71, the gas to be filtered, which may be an exhaust gas from a CMC-machine, flows from the inlet 7 upwards through the device housing 2, and thereby sequentially through the plurality of filter units 3, 4, 5, 6 and further to the outlet 8. The outlet 8 is here simply indicated as an upper side of the fan module 10. A connection to an exhaust conduit may be arranged on top of the fan module 10.

[0059] The plurality of filter units comprises a first (upper) oil filter unit 5 provided with a filter element 51 configured to separate oil-based particles from a gas that flows through the filter element 51. In this example the filtration device comprises also a second (lower) oil filter unit 4 located below the first oil filter unit 5. The first and second oil filters 4, 5 are in this case identical and the terms “first” and “second” are used simply to distinguish between these two filter units. Either of these oil filters can be considered to be the “first” oil filter unit. A single oil filter may be sufficient depending on the application.

[0060] Additional filter units in the filtration device of figures 1-6 are a lower filter unit 3 provided with a coarse filter element 31 and located below both oil filter units 4, 5 and an upper filter unit 6 provided with a fine filter element 61 and located above both oil filter units 4, 5.

[0061] All filter units 3, 4, 5, 6, and also the fan unit / module 10, form in this case modular filter units, each having a module housing that is connectable to another module housing so as to form the device housing 2 when connected to each other.As shown in figures 6-8, and partly also in figures 4-5, a filter cassette 100 is provided that is to be arranged in the first oil filter unit 5 (as well as in the second oil filter unit 4, but the figures and the description below focuses on the first oil filter unit 5). The filter cassette 100 comprises a filter element 51 configured to separate oil-based particles from a gas that flows through the filter element 51 and a module frame 52 arranged to be oriented in a substantially horizontal position when installed in the filtration device 1.

[0062] As shown in e.g. figures 2-3, the module frame 52 is arranged to hold the filter element 51 in an inclined position in relation to a horizontal plane when installed in the filtration device 1 so that also the lower side of the filter element 51 is inclined and so that oil-based liquid originating from oil-based particles trapped in the first filter element 51 flows not only downwards but also sideways towards a lower edge 53 of the inclined filter element 51 , see figure 8. The lower edge 53 is thus located at the rear of the device housing 2 when the filter cassette 100 is properly installed in the filtration device 1. As described further above, the trapped oil-based liquid will then not simply drop down over the entire filter located below but instead accumulate at and flow down along the rear wall of the device housing 2, which extends the service life of the filter located below. A drainage system may be arranged at the rear wall of the device housing 2 to take care of the accumulated oil.

[0063] Each module / unit has a module door that may be opened to allow access to the inside and allow for exchange of filter. Figures 4-6 show the filtration device 1 with the module door of the first oil filter unit 5 removed.

[0064] Figure 4 shows the filter cassette 100 properly installed in the filtration device 1 by means of a pressing / clamping arrangement 9 that, when activated, presses the filter cassette 100 upwards to provide a seal (see also below) and locks / clamps the filter cassette 100 in the intended operational position.Figure 5 shows the situation when the pressing / clamping arrangement 9 has been released and the filter cassette 100 can be slided out horizontally from the filtration device 1. Figure 6 shows the filter cassette 100 when removed from the filtration device 1. Installation of the filter cassette 100 follows a reverse order, i.e. sliding the filter cassette 100 in place horizontally in the first filter unit 5 and activate the pressing / clamping arrangement 9 (by turning left and right handles upwards). When the first filter element 51 is used and needs to be replaced, the entire filter cassette 100 is typically exchanged. A used filter element 51 is typically sent for destruction while the module frame 52 may be disassembled and reused.

[0065] Figures 9a-9c show that the oil filter element 51 in this example comprises a filter medium folded into a layered structure so as to form a plurality of substantially vertically extending filter medium layers 51a arranged side by side with spacers 51b arranged between the filter medium layers 51a. The filter element 51 is oriented so that the lower edge 53 of the inclined filter element 51 extends in a direction perpendicular to the filter medium layers 51a. The oil-based liquid can thus flow along the layer edges downwards toward the lower edge 53. The layered structure, i.e. the filter element 51, has the shape of a rectangular cuboid (a “box”) and it is arranged in a filter frame 54 having a corresponding shape, see figures 7-9.

[0066] As shown in figure 7-8, the filter frame 54, and thereby the filter element 51, is fastened to the module frame 52 so as to form the integrated filter cassette 100. Exchange of the filter element 51 can thus be done by exchanging the filter cassette 100. The module frame 52 has in this case two opposite side walls 57A, 57B, a rear wall 58A and an upper front portion 58B that connects the two opposite side walls 57A, 57B. Further, the module frame 52 is provided with support members 59 that holds the filter frame 54 in place in an inclined position between the side walls 57A, 57B of the module frame 52 with a rear side of the filter frame 54 in contact with the rear wall 58A of the module frame 52.The side walls 57a, 57b, or rather the undersides thereof, forms left and right (horizontal) support surfaces 25a, 25b (see figure 7d) for the filter cassette 100 for use when installing it in the filtration device 1 , for instance, they form support surfaces for (horizontal) parts / bars of the pressing / clamping arrangement 9 that presses the filter cassette 100 upwards when mounting the filter cassette 100.

[0067] As shown in figures 7a, 7b and 8, the module frame 52 is provided with a flange 55 that extends circumferentially in a horizontal plane around the module frame 52 at an upper part thereof, and a sealing member 56 is arranged on an upper side of the flange 55. This sealing member 56 provides a seal against a corresponding flange in the device housing 2 when the filter cassette 100 is installed.

[0068] The invention is not limited by the embodiments described above but can be modified in various ways within the scope of the claims. For instance, the inclined filter element may instead be e.g. a carbon filter or a HEPA filter and it is in principle sufficient that the lower side of the filter element is inclined, so if the lower and upper sides are not parallel, the upper side may be e.g. horizontal. Further, the liquid trapped in the inclined filter element does not have to be oil-based but could be water-based, or a mix of oil- and waterbased liquid. The inclined (lower side of) the filter element is useful also when e.g. removing water or water-based liquid from a gas flow. Further, the filtration device may comprise various filter unit configurations; for instance, the filter unit provided with the inclined filter element may form the unit closest to the inlet and / or closest to the outlet of the device (instead of being positioned between horizontally oriented filter elements as exemplified above), and various filter types may be used in different inclined filter elements, etc. Moreover, the module frame may be structured in other ways.Figure references

[0069] 1 - filtration device

[0070] 2 - device housing

[0071] 3 - lower filter unit

[0072] 31 - coarse filter element

[0073] 4 - second oil filter unit

[0074] 41 - inclined filter element of second oil filter element 4

[0075] 5 - first oil filter unit

[0076] 51 - inclined filter element of first oil filter unit 5

[0077] 51a - vertically extending filter medium layers

[0078] 51b - spacers between filter medium layers 51a

[0079] 52 - module frame of first oil filter unit 5

[0080] 53 - lower edge of inclined filter element 51

[0081] 54 - filter frame for filter element 51

[0082] 55 - upper flange of module frame 52

[0083] 56 - sealing member on flange 55

[0084] 57a, 57b - side walls of module frame 52

[0085] 58a - rear wall of module frame 52

[0086] 58b - upper front portion of module frame 52

[0087] 59 - support members

[0088] 6 - upper filter unit

[0089] 61 - fine filter element

[0090] 7 - inlet

[0091] 71 - fan

[0092] 8 - outlet

[0093] 9 - pressing / clamping arrangement

[0094] 10 - fan unit / module

[0095] 25a, 25b - support surfaces at lower portion of side walls 57a, 57b 100 - filter cassette comprising filter element 51 and module frame 52

Claims

CLAIMS1. A filtration device (1) for cleaning of a gas flow, such as for removing e.g. oil-based particles from a gas flow exhausted from a CNC machine, wherein the filtration device (1) comprises:- a device housing (2);- a plurality of filter units (3, 4, 5, 6) arranged on top of each other inside the device housing (2);- an inlet (7) for an incoming gas flow arranged in a lower portion of the device housing (2);- an outlet (8) for an outgoing gas flow arranged in an upper portion of the device housing (2),wherein the filtration device (2) is configured so that, during operation of the filtration device, the gas to be filtered flows from the inlet (7) upwards through the device housing (2), and thereby sequentially through the plurality of filter units (3, 4, 5, 6) and further to the outlet (8),wherein the plurality of filter units (3, 4, 5, 6) comprises a first filter unit (5) provided with a filter element (51) configured to separate particles, such as oil-based particles, from a gas that flows through the filter element (51), wherein the first filter unit (5) comprises a module frame (52) arranged to be inserted into and removed from the filtration device (1) in a substantially horizontal direction and to be oriented in a corresponding substantially horizontal position when installed in the filtration device (1),wherein the module frame (52) is arranged to hold the filter element (51) in an inclined position in relation to a horizontal plane when installed in the filtration device (1) so that at least a lower side of the filter element (51) is inclined in relation to the horizontal plane allowing oil-based or other liquid originating from particles trapped in the filter element (51) to flow not only downwards but also sideways along the inclined lower side towards a lower edge (53) of the inclined filter element (51 ).

2. The filtration device (1 ) according to claim 1 , wherein the filter element (51 ) comprises a filter medium folded into a layered structure so as to form a plurality of substantially vertically extending filter medium layers (51a) arranged side by side.

3. The filtration device (1) according to claim 2, wherein the filter element (51) is oriented so that the lower edge (53) of the inclined filter element (51) extends in a direction perpendicular to the filter medium layers (51a).

4. The filtration device (1) according to claim 2 or 3, wherein spacers (51b) are arranged between the filter medium layers (51a).

5. The filtration device (1) according to any of the above claims, wherein the filter element (51 ) has the shape of a rectangular cuboid.

6. The filtration device (1) according to any of the above claims, wherein the filter element (51 ) is arranged in a filter frame (54).

7. The filtration device (1) according to any of the above claims, wherein the filter element (51) is directly or indirectly fastened to the module frame (52) so as to form a filter cassette (100) comprising the module frame (52) and the filter element (51), and wherein the module frame (52) is removable from the filtration device (1) so as to allow for exchange of the filter element (51) by exchanging the filter cassette (100).

8. The filtration device (1) according to any of the above claims, wherein the module frame (52) is provided with a flange (55) that extends circumferentially around the module frame (52) at an upper part thereof.

9. The filtration device (1) according to claim 8, wherein a sealing member (56) is arranged on an upper side of the flange (55).1810. The filtration device (1) according to claim 8 or 9, wherein the flange (55) extends in a horizontal plane.

11. The filtration device (1 ) according to any of the above claims, wherein the module frame (52) has two opposite side walls (57A, 57B), a rear wall (58A) and an upper front portion (58B) that connects the two opposite side walls (57A, 57B).

12. The filtration device (1 ) according to claims 6 and 11 , wherein the module frame (52) is provided with support members (59) that holds the filter frame (54) in place in an inclined position between the side walls (57A, 57B) of the module frame (52).

13. The filtration device (1) according to any of the above claims, wherein the filtration device (1) comprises one or more additional filter units (3, 4, 6) arranged below and / or above the first filter unit (5).

14. The filtration device (1) according to claim 13, wherein the one or more additional filter units comprises one or more of the following:- a lower filter unit (3) located below the first filter unit (5) and being provided with a coarse filter element (31 );- a second filter unit (4) located below or above the first filter unit (5), wherein the second filter unit (4) is arranged in the same way as the first filter unit (5); and / or- an upper filter unit (6) located above the first filter unit (5) and being provided with a fine filter element (61 ).

15. The filtration device (1) according to any of the above claims, wherein the plurality of filter units (3, 4, 5, 6) forms modular filter units, each having a module housing that is connectable to another module housing so as to form the device housing (2) when connected.1916. A filter cassette (100) for a filtration device (1 ), wherein the filter cassette (100) comprises:- a filter element (51) configured to separate particles, such as oil-based particles, from a gas that flows through the filter element (51 ); and- a module frame (52) arranged to be oriented in a substantially horizontal position when installed in the filtration device (1),wherein the module frame (52) is arranged to hold the filter element (51) in an inclined position in relation to a horizontal plane when installed in the filtration device (1) so that at least a lower side of the filter element (51) is inclined in relation to the horizontal plane allowing oil-based or other liquid originating from particles trapped in the filter element (51) to flow not only downwards but also sideways along the inclined lower side towards a lower edge (53) of the inclined filter element (51 ).

17. The filter cassette (100) according to claim 16, wherein the filter element (51) comprises a filter medium folded into a layered structure so as to form a plurality of filter medium layers (51a) arranged side by side, wherein the filter element (51) is arranged so that the filter medium layers (51a) extend vertically when the module frame (52) is oriented in the substantially horizontal position.

18. The filter cassette (100) according to claim 17, wherein the filter element (51) is oriented so that the lower edge (53) of the inclined filter element (51) extends in a direction perpendicular to the filter medium layers (51a).

19. The filter cassette (100) according to claim 17 or 18, wherein spacers (51b) are arranged between the filter medium layers (51a).

20. The filter cassette (100) according to any of claims 16-19, wherein the filter element (51) has the shape of a rectangular cuboid, and wherein the first filter element (51 ) is arranged in a filter frame (54).2021. The filter cassette (100) according to any of claims 16-20, wherein the module frame (52) is provided with a flange (55) that extends circumferentially around the module frame (52) at an upper part thereof, wherein the flange (55) extends in a horizontal plane when the module frame (52) is oriented in the substantially horizontal position.

22. The filter cassette (100) according to claim 21 , wherein a sealing member (56) is arranged on an upper side of the flange (55).

23. The filter cassette (100) according to any of claims 16-22, wherein the module frame (52) has two opposite side walls (57A, 57B), a rear wall (58A) and an upper front portion (58B) that is connected to the two opposite side walls (57A, 57B).

24. The filter cassette (100) according to claims 20 and 23, wherein the module frame (52) is provided with support members (59) that holds the filter frame (54) in place in an inclined position between the side walls (57A, 57B) with a rear side of the filter frame (54) in contact with the rear wall (58A) of the module frame (52).

25. The filter cassette (100) according to claim 23 or 24, wherein a lower portion of each of the side walls (57A, 57B) forms a support surface (25A, 25B) that extends in a horizontal plane when the module frame (52) is oriented in the substantially horizontal position.

Images