HK1166748B - Filter cassette, filter arrangement, and gas turbine with such filter cassette - Google Patents

Description

Filter cassette, filter arrangement and gas turbine having such a filter cassette

Technical Field

The present invention relates to a filter cassette for removing particles from an air stream, and in particular to a filter arrangement comprising a partition having an opening in which the filter cassette is mounted. The invention also relates in particular to the use of a filter cassette for removing particles from a gas stream entering a gas turbine and to such a gas turbine as a specific application. However, the invention is also likely to be used in various other applications, such as emergency power generators, gas compressors, HVAC systems, gas mining operations to extract gas from brine aquifers, and the like.

Background

Common to the aforementioned applications is that they require the filtration of large volumes of air with high particulate filtration efficiency. When the individual filter cartridges have a filtration performance of more than 1,000m per hour³When it is used, it is usually made in a filter size of 592 mm. times.592 mm. times.300 mm or 610 mm. times.610 mm. times.300 mm, and it filters about 2,500 to 5,000m per hour³A large number of filter cassettes are used in parallel to filter more than 10,000m per hour³Or even more than 150,000m per hour³Sometimes even far above. The filter cassette or cassette bank is mounted on a partition separating an upstream volume, commonly referred to as the "dirty air section", from a downstream volume, commonly referred to as the "clean air section". The partition may be in the form of a wall with an opening in which the filter cassette is mounted, or in the form of a bracket defining a plurality of openings in which the filter cassette is mounted, thereby to form a substantially air impermeable partition between the dirty air and clean air sections. In some applications, a large number of filter cartridges are provided in a filter chamber that is large enough to enable an operator to walk in and remove and replace individual clogged or defective filter cartridges.

US6,368,386 relates to an air filtration system in the air intake flow of a gas turbine. Particulate material is filtered from the intake air in the first stage air cleaner and directed to the second stage air cleaner to remove moisture and, in particular, salt from the intake air. The second stage air purifier typically includes the aforementioned filter cartridge. A filter material that can be advantageously used as a filter medium in a second stage air cleaner is described, for example, in EP 1674144 a 1. The construction of filter cassettes in general is described, for example, in WO2007/103408, EP 0560012B 1 and EP 0723800B 1. Accordingly, the filter cassette typically comprises a plurality of filter panels arranged such that each pair of panel filters forms a V-shaped pocket extending from an upstream end of the filter cassette to a downstream end of the filter cassette. Each filter panel is comprised of a plurality of pleats of filter media extending generally parallel to the overall filter passage, thereby allowing filtered air or gas to pass through the pleats in a generally direct manner. The filter panels are mounted in the housing and fit air-tightly over the mounting frame at the upstream end of the filter cassette or, in a small number of applications, at the downstream end of the filter cassette. The mounting frame provides a mounting face for mounting the filter cassette to a corresponding mounting face on the partition such that the filter cassette extends into and through the partition opening into the clean air section. The operator can then easily remove and replace the filter cassette from the dirty air section side.

The object of the present invention is to improve existing filter cassettes and filter arrangements, in particular in terms of filtration efficiency, service life and pressure drop.

Disclosure of Invention

Accordingly, the filter cassette of the present invention has an upstream end and a downstream end and comprises a mounting frame for cooperating with the filter media, and the mounting frame has a mounting face adapted for mounting the filter cassette to the opening of the partition, as described earlier in relation to the prior art. According to the invention, the mounting surface is located between the upstream end and the downstream end of the filter cassette, at a first distance from said upstream end and at a second distance from said downstream end. The first distance and the second distance account for more than 10% of the total length of the filter cassette. In particular, the first and second distances are at least 40mm, more preferably 100mm or more. Such an arrangement reduces the torque induced on the partition by the filter cassette which can result in poor sealing pressure and air bypassing the frame gasket. It is also possible to prevent the torque from exceeding the structural integrity of the diaphragm.

In a preferred embodiment, the distance from the mounting faces of the upstream and downstream ends of the filter cassette is more than 15%, preferably more than 20%, more preferably more than 25% of the total length of the filter cassette. The absolute values of these distances are preferably 100mm or more. Most preferably, the mounting surface is located on a line of gravity of the filter cassette relative to the upstream and downstream ends. Thus, the mounting face is advantageously located centrally of the upstream and downstream ends, assuming that the filter cassette has a symmetrical configuration.

Another advantage of the proposed construction is that by the filter cassette protruding into the air clearance section, the surface area of the filter medium can be increased without having to increase the length. That is, the filter cassette of the present invention instead extends partially into the dirty air section. Thus, existing filter cassettes can be replaced with filter cassettes of the present invention having a greater filtration surface area without the need to accommodate the partition or chamber in which the filter cassette is to be installed. As a result of the increased filter surface area, filter life may be increased due to less air passing over each portion of the filter surface and a lower rate of air passing through the filter media.

The arrangement proposed by the present invention for placing the mounting face of the mounting frame between the upstream and downstream ends of the filter cassette provides even further advantages when not only the mounting face but also the entire mounting frame is placed somewhere between the upstream and downstream ends of the filter cassette. That is, placing the mounting frame at the upstream (or downstream) end of the filter cassette and having a length in the upstream to downstream direction such that the mounting face of the mounting frame is located, for example, on the center of gravity line of the filter cassette, substantially achieves the aforementioned advantages. However, it is particularly advantageous to arrange the mounting frame in the region of the filter cassette that mounts the filter cassette to the partition via the mounting face and to seal the mounting frame in this region in a gas-tight manner to the filter panels. The weight of the mounting frame and thus the weight of the filter cassette is correspondingly reduced. Furthermore, the torque generated by the filter panels on the filter frame is similarly reduced. Further, the side walls provided on the mounting frame between the filter panels can be distributed between the upstream surface sides of adjacent filter panels. Thereby further reducing the overall weight of the filter cassette and, more importantly, the pressure drop caused by the filter cassette is also greatly reduced. When placed in an air stream, the differential pressure caused by the filter cassette is always one of the most important characteristic values for the filter cassette. A pressure drop of 1,000Pa may be equivalent to a power loss of the turbine of 1 to 3%. Since the upstream mounting frame side wall is only provided between the downstream surface sides of adjacent filter panels and not between the upstream surface sides, the area of air entry into the filter cassette is increased compared to the open area of the prior art filter cassette where it does not protrude into the dirty air section. Thus, the air to be filtered enters the filter cassette at a reduced rate. Overall, this will result in a reduced pressure drop across the filter cassette and thereby improve the performance of the steam turbine.

Similarly, the flow resistance of the air can be further reduced by providing the downstream side wall of the mounting frame only between the upstream surface sides of adjacent filter panels, thereby enabling a further improvement in the pressure drop through the cartridge. Most preferably, both measures are combined, i.e. the mounting frame side wall is arranged upstream only between the downstream surface sides of adjacent filter panels, and the mounting frame side wall is arranged downstream only on the upstream surface sides of adjacent filter panels.

Although it has been mentioned that the side walls between the filter plates can be partly diverging, it is further advantageous to form the walls of the top and bottom of the filter cassette from the filter plates. Generally, the walls of the filter cassette may be made of a strong material, such as a metal or a hard polymeric material, to enhance the overall structure of the filter cassette. However, when these walls are constituted by the outermost two filter plates, a filtering function is provided. This allows the air to pass not only from the front end through the V-shaped pockets and the by-pass where the side walls are partially dispersed, but also directly through the two outermost filter panels, i.e. through the walls of the top and bottom of the filter cassette, when passing through the filter media of the filter cassette. Thereby enabling the efficiency, life and pressure drop of the filter cassette to be further improved compared to prior art filter cassettes.

The use of such a filter cassette with a filter medium can provide a filtration efficiency of at least the filtration class H10, preferably H12 (according to EN1822), at an air flow of 3,400cm per hour³A pressure drop below 200Pa can be achieved. Depending on whether the side wall is dispersed inEven better values of 180Pa, 160Pa, 140Pa, 120Pa, and even below 100Pa can be obtained on the upstream side, on the downstream side or both, and depending on whether one or both of the two outermost filter panels provide a filtering function such that air passes through the filter media from the top to the bottom of the filter cassette.

Of course, the pressure drop is largely dependent on the material used as the filter medium. Materials as described in EP 1674144 are particularly preferred for use as filter media in filter cassettes. Other materials are mentioned in the following detailed description of preferred embodiments.

Thus, a filter cassette according to a preferred embodiment of the invention has an upstream end and a downstream end and comprises a mounting frame for cooperating with a filter medium, and the mounting frame has a mounting face adapted to mount the filter cassette to an opening in a partition, wherein the mounting face is located between the upstream end and the downstream end of the filter cassette at a first distance from said upstream end and at a second distance from said downstream end. Each of the first distance and the second distance comprises more than 10% of the total length of the filter cassette, wherein the first and second distances are at least 40 mm.

A filter cassette according to another preferred embodiment of the invention has an upstream end and a downstream end and includes a mounting frame for mating with a filter media and having a mounting face adapted to mount the filter cassette to an opening in a partition, wherein the mounting face is located between the upstream end and the downstream end of the filter cassette at a first distance from the upstream end and at a second distance from the downstream end. Each of the first and second distances accounts for more than 25% of the total length of the filter cassette.

A filter cassette according to a still further preferred embodiment of the invention has an upstream end and a downstream end and comprises a mounting frame for cooperating with the filter media, and the mounting frame has a mounting face adapted for mounting the filter cassette to an opening in the partition, wherein the mounting face is located between the upstream end and the downstream end of the filter cassette at a first distance from said upstream end and at a second distance from said downstream end. Each of the first and second distances comprises more than 10% of the total length of the filter cassette, wherein the filter media comprises a plurality of filter panels extending in an upstream to downstream direction, wherein the filter panels are connected in an alternating manner at their upstream and downstream ends and the side walls connect adjacent filter panels, thereby forcing fluid flowing through the filter cassette to pass through the filter panels.

Filter cassettes of the above type can be advantageously used for removing particles from the gas stream entering a high performance gas turbine. The individual filter cassettes can have a height of 500 to 6,000m per hour³While a plurality of filter cartridges used in parallel achieve a filtration of 1,000m per hour³Or 4,000m per hour³Or even more than 10,000m per hour³。

Brief Description of Drawings

Fig. 1 is a side perspective view of a filter cassette according to the present invention.

Fig. 2 is a schematic cross-sectional view of a filter cassette similar to the first embodiment shown in fig. 1.

Fig. 3 is a schematic cross-sectional view of a filter cassette similar to the second embodiment shown in fig. 1.

Fig. 4 is a schematic cross-sectional view of a filter cassette similar to the third embodiment shown in fig. 1.

Fig. 5 is a diagram of a filter arrangement of a filter cassette of the prior art.

Detailed description of the drawings

Figure 5 shows a prior art filter arrangement in which a prior art filter cassette is mounted in an opening in a partition 6. The partition 6 is shown here in the shape of a wall to separate a dirty air section at the upstream end 14 of the filter cassette from a clean air section at the downstream end 16 of the filter cassette 1. The filter cassette 1 is made up of a plurality of filter panels 2 arranged in a V-bank row, extending in an upstream to downstream direction. The filter plates are connected in an alternating manner at their upstream and downstream ends. The connection at the upstream end 14 is in the form of a mounting frame 8. The mounting frame 8 projects laterally so as to form a mounting surface 5 on its downstream side. The mounting face 5 surrounds the filter panel assembly so that the filter cassette 1 can be mounted to the partition 6 in a substantially airtight manner by means of a mounting frame 8, wherein the mounting face 5 has a sealing function. When the air to be cleaned passes through the filter cassette 1, it enters the filter cassette 1 through an opening in the mounting frame 8, passes through the filter media 4 on the filter panels 2 from its upstream surface side 17 to its downstream surface side 18 and exits the filter cassette 1 from its downstream end 16. Typical filter cassettes of the prior art have a length of about 300mm and are designed to fit over an opening of about 560 x 560mm or 580 x 580 mm.

The side walls 10 provide the necessary strength to maintain the required V-bank of filter panels 2 and to force the air to be cleaned through the filter panels 2.

The filter cassette according to the invention described herein relates to embodiments which differ from the prior art constructions outlined above only in terms of the mounting frame and mounting surface. Thus, the same reference numerals are used hereinafter to describe specific embodiments of the present invention.

Fig. 1 shows that in a first embodiment, the filter cassette 1 is mounted in the opening 15 of the partition 6. As in the prior art, two adjacent filter panels 2 form a V-bank. The filter plate of each V-bank is hermetically connected at the downstream end 16 of the filter cassette, for example by a suitable potting material. Similarly, the filter plates 2 of two adjacent V-banks are air-tightly connected at the upstream end 14 of the filter cassette, for example also by a suitable potting material. The mounting frame 8 is connected to the filter plate assembly so as to enable mounting of the filter cassette 1 by its mounting face 5 to a corresponding mounting face 13 on the partition 6, which is centrally located between the upstream and downstream ends 14,16 of the filter cassette 1, substantially on the centre line of gravity of the filter cassette. Thus, as in the prior art, the air to be filtered on the dirty-air section side of the filter cassette 1 passes through the upstream surface side 17 of the filter media 4 of the filter plates 2 and out through the downstream surface side 18 of the filter media 4 of the filter plates 2 into the clean-air section.

The mounting frame 8 not only stabilizes the filter panels 2, but also seals the filter panels 2 and their filter media 4 in a leak-free, i.e. airtight manner. The filter plate 2 is further stabilized by top and bottom walls 19 of a strong material, such as a metal or a hard polymer material. Since the position of the mounting surface 5 is approximately on the center of gravity line of the entire filter cassette 1, the torque generated by the filter cassette 1 on the partition 6 is minimized. Furthermore, the length of the filter plates 2 from upstream to downstream may be multiplied by a total length of about 300mm of the filter cassette to a total length of about 600mm of the filter cassette, thereby correspondingly increasing the filter area. This will improve the service life of the filter cassette.

It is most preferred to locate the mounting face 5 centrally between the upstream and downstream ends 14,16 of the filter cassette, at a distance D from the upstream end 14_{On the upper part}And a distance D from the downstream end 16_{Lower part}Equal or substantially equal, the mounting surface is located substantially on the center of gravity line of the filter cassette. However, the aforementioned positive effects have been partly achieved when the mounting face 5 is only slightly towards the centre of the filter cassette, as compared to the prior art filter cassette where the mounting frame 8 with the mounting face 5 is arranged at the upstream (or downstream) end of the filter cassette. It should also be mentioned here that, unlike the embodiment of fig. 1, the mounting face 5 can be arranged on the upstream side of the mounting frame 8 or vice versa when the filter cassette is mounted from the free air section side into the opening 15 of the partition 6. Alternatively, when the mounting frame 8 is accurately fitted to the opening 15, the mounting surface 5 may be constituted by a surrounding side surface of the mounting frame. In both cases, the mounting surface 5 has a sealing function and may comprise a gasket.

It should be further noted that, although preferred, the mounting frame 8 need not be disposed completely around the opening 15 of the filter plate structure or partition. For example, if there is a tight fit between the filter panel arrangement and the opening 15 of the partition, the mounting frame 8 may be provided only in certain parts, such as those on the top or bottom side of the filter cassette where a major torque is expected.

As can further be seen from fig. 1, the side walls 10 are partially distributed both on the clean air section side of the filter cassette and on the dirty air section side of the filter cassette. The side walls 10 are only provided in the areas where air flow must be blocked between adjacent plates. More particularly, in the dirty-air section, i.e. upstream of the mounting frame 8, the side walls 10 are only arranged between the downstream surface sides 18 of adjacent filter panels 2, whereas in the clean-air section, i.e. downstream of the mounting frame 8, the side walls 10 are only arranged between the upstream surface sides 17 of adjacent filter panels 2. The total area of air entering the filter cassette is thereby increased, so that the speed of air entry and the corresponding flow resistance are significantly reduced. This has a beneficial effect on the pressure drop caused by the filter cassette in the air stream. Thus, under a convergence of two effects: increasing the length of the filter panels and thereby the effective filter area of the filter panels, the speed of air passing through the filter panels is significantly reduced, and the air flow rate is also reduced by the partial absence of the side walls to increase the cross-sectional area of air entering the filter cassette.

As shown generally in fig. 1 and 6, the filter media 4 of the filter panels 2 is pleated in an upstream to downstream direction. In this embodiment, the pleats themselves are oriented from the upstream end 14 to the downstream end 16 of the filter cartridge. In other embodiments, the pleats may extend from one side of the filter plate 2 to the opposite side. The filter medium 4 may comprise cellulose or glass fibers or synthetic materials such as polyester nonwovens or polypropylene nonwovens. It is particularly preferred to use a composite filter medium having at least two superposed filter layers, one of which is preferably a membrane filter layer and the other a depth filter layer. The depth filtration layer may comprise nanofibers or glass fibers, nonwoven fibrous polymer webs, such as spunbond, nonwoven, fiberglass, microfiber glass, cellulose, or polytetrafluoroethylene. The depth filtration layer is preferably a meltblown web. The meltblown polymer web or laminate may be formed from a variety of polymeric materials including polypropylene, polyester, polyamide, polyvinyl chloride, polymethyl methacrylate and polyethylene, with polypropylene being most preferred. Typically, the polymeric fibers forming the web have a diameter in the range of about 0.05 μm to about 10 μm, preferably about 1 μm to about 5 μm.

Preferably, at least one depth filter media is formed as an electret filter media comprising a high efficiency layer having an electrostatic charge. Electrical charge is imparted to meltblown fibers to improve their filtration properties by various known technical means (see, e.g., U.S. Pat. No. 5,401,446). A membrane filtration layer is disposed downstream of the depth filtration layer or filter stack of the composite filter media to capture particles that pass through the depth filtration layer. A variety of microporous polymeric membranes may be used as the membrane filtration layer depending on the requirements of the application. The membrane filtration layer may be constructed using the following exemplary materials: nitrocellulose, triacetyl cellulose, polyamide, polycarbonate, polyethylene, polypropylene, polytetrafluoroethylene, polysulfone, polyvinylidene fluoride, acrylate copolymers. The membrane filtration layer is preferably constructed of a hydrophobic material that is capable of preventing liquid from passing through. This is further illustrated in EP 1674144 a1 and US7,501,003B. Preferably, the membrane filtration layer is a microporous fluoropolymer, such as expanded ptfe (eptfe), Fluorinated Ethylene Propylene (FEP), perfluoroalkoxy Polymer (PFA), polypropylene (PP), Polyethylene (PE) or ultra high molecular weight polyethylene (PE-UHMW). Particularly suitable ePTFE membranes are described in US5,814,405. Further information on suitable materials, their properties and corresponding test methods are referred to EP 1674144 a 1.

The overall dimensions of the filter cassette shown in figure 1 are typically 592mm by 592mm or 610mm by 610mm frame dimensions and an overall length L of about 600 mm. The thickness of the filter frame is about 20 mm. Typically, three V-bank filter panels 2 are arranged in the filter cassette. The surface area of the pleated filter media 4 in the filter cassette 1 can exceed 40m²。

The filter cassette 1 is preferably used and can be at 4,250m³A filter material providing a particle filtration efficiency (according to EN1822) of class H12 in an air stream of H or less. The air distribution ratio is less than 3cm/s, and the service life is more than 1 year in the ambient air. Other characteristic values obtained with the filter cartridge of the above dimensions are: the wet burst pressure exceeds 6,200Pa and is at 4,250m³The initial pressure drop in the air stream of/h is less than 300 Pa.At 3,400m³In the air flow/h, the initial pressure drop is less than 200Pa, and when the side wall 10 is partially or substantially distributed and depending on the overall length of the filter cassette, it can be further reduced to less than 180Pa, 160Pa, 140Pa, 120Pa and even less than 100 Pa.

Fig. 2 is a schematic cross-sectional view of the filter cassette of fig. 1, but with only two V-banks, i.e. with four filter plates 2. The filter material 4 of the filter plate 2 is pleated such that the pleats extend from one side (not shown) of the plate to the opposite plate side (not shown), whereby the filter material forms a zigzag-like configuration in said cross-sectional view. As can be seen, the mounting frame 8 is connected to the upper and lower mounting plates 19 and the filter panels 2 are connected at their upstream ends. In this embodiment, the mounting plate 19 does not have any filtering function.

Fig. 3 shows a different embodiment from a similar perspective as fig. 2. In this embodiment, the two upper and lower mounting plates 19 are eliminated and replaced by the filter plate 2. As can be seen by comparing the embodiments of fig. 2 and 3, the amount of filter panel material is the same in both embodiments, but provides more open area on the upstream side (dirty air section) for air to enter the filter cassette. That is, the air to be filtered can enter the filter cassette from either the upper or lower side, which in the first embodiment shown in fig. 1 and 2 is blocked by the mounting plate 19. Accordingly, the filter cassette according to the second embodiment of fig. 3 will cause a lower pressure drop than the filter cassette according to the first embodiment, all other things being equal.

Figure 4 shows an alternative to the mounting of the filter cassette of figures 1 and 2 to a partition wall 6 by use of its mounting face 5. Fig. 4 shows a typical arrangement corresponding to the view of fig. 1, with the filter panels 2 of the filter cassette 1 extending into the clean air section.

The following paragraphs describe preferred embodiments of the present invention

1. A filter cassette (1) for removing particles from an air stream, the filter cassette having an upstream end (14) and a downstream end (16), and comprising a mounting frame (8) for cooperating with a filter medium (4), the mounting frame (8) having a mounting face (5) adapted to mount the filter cassette to an opening in a partition (6), wherein the mounting face (5) is located between the upstream and downstream ends (14,16) of the filter cassette at a first distance (D) from the upstream end (14)_{On the upper part}) At a second distance (D) from said downstream end (16)_{Lower part}) Said first and second distances (D)_{On the upper part}，D_{Lower part}) Each of which accounts for more than 10% of the total length (L) of the filter cassette.

2. A filter cassette (1) as in paragraph 1 wherein said first and second distances (D)_{On the upper part}，D_{Lower part}) Is at least 40mm, more preferably 100mm or more.

3. A filter cassette (1) as in paragraph 1 or 2 wherein said first and second distances (D)_{On the upper part}，D_{Lower part}) Each of which accounts for more than 25%.

4. A filter cassette (1) as in paragraph 1 or 2 wherein said mounting face (5) is located centrally of said upstream and downstream ends (14,16) with respect to said overall length (L) of the filter cassette.

5. The filter cassette (1) of any of paragraphs 1 to 4, wherein the mounting surface (5) is located on a line of gravity of the filter cassette relative to the upstream and downstream ends (14, 16).

6. A filter cassette (1) according to any of paragraphs 1 to 5, wherein said filter medium (4) comprises a plurality of filter panels (2) extending in an upstream to downstream direction, wherein said filter panels (2) are connected in an alternating manner at their upstream and downstream ends (14,16) and the side walls (10) connect adjacent filter panels (2), thereby forcing fluid flowing through the filter cassette through said filter panels.

7. A filter cassette (1) as in paragraph 6 wherein the filter media (4) is pleated in an upstream to downstream direction.

8. A filter cassette (1) as in paragraph 6 or 7 wherein said mounting frame (8) is connected to said filter panels (2) in the region of the filter cassette (1) where the filter cassette is mounted to said partition (6) by said mounting face (5).

9. A filter cassette (1) as in paragraph 8 wherein the side walls (10) are provided only between downstream surface sides (18) of adjacent filter panels (2) upstream of the mounting frame (8).

10. A filter cassette (1) as in paragraph 8 or 9 wherein downstream of the mounting frame (8) the side walls (10) are provided only between upstream surface sides (17) of adjacent filter panels (2).

11. A filter cassette (1) as in paragraph 8, wherein the side walls (10) are provided upstream of the mounting frame (8) only between downstream surface sides (18) of adjacent filter panels (2) and the side walls (10) are provided downstream of the mounting frame (8) only between upstream surface sides (17) of adjacent filter panels (2).

12. A filter cassette (1) according to any of paragraphs 8 to 11, wherein two outermost filter panels extend from said upstream and/or downstream ends (14,16) to said mounting face (5) and have a filter function.

13. The filter cassette (1) according to any of paragraphs 1 to 12, wherein the total length of the filter cassette is equal to or greater than 250 mm.

14. A filter cassette (1) as in any of the paragraphs 1 to 13, wherein the mounting face (5) has a sealing function.

15. A filter cassette (1) according to any of paragraphs 1 to 14, wherein the filter medium (4) has a particle filtration efficiency according to EN1822 of at least filter grade H10, preferably filter grade H12, at 3,400 m/hour³Is less than 200 Pa.

16. A filter cassette (1) as in paragraph 15 wherein 3,400m per hour³Is less than 180Pa, preferably less than 160Pa, more preferably less than 140Pa, even more preferably less than 120Pa, most preferably less than100Pa。

17. A filter cassette (1) as in any of paragraphs 1 to 16 wherein the filter media (4) comprises one or more of the following filtration layers: glass fiber filter layers, such as synthetic fiber filter layers made of non-woven polyester or non-woven polypropylene; a cellulose filter layer.

18. A filter cassette (1) as in any of paragraphs 1 to 17, wherein the filter medium (4) is a composite material comprising a plurality of adjacent filter layers, preferably one or more of the following: at least one ePTFE membrane, at least one layer of nanofibers, at least one layer of glass fibers, and an electrostatically charged nonwoven layer.

19. A filter arrangement comprising a partition (6) having an opening (15) and a mounting face (13) surrounding the opening (15), wherein a filter cassette (1) as in any of paragraphs 1 to 18 is mounted to the partition mounting face (13) such that the filter media (4) of the filter cassette projects to either side of the partition mounting face (13).

20. A gas turbine comprising one or more filter cassettes (1) as claimed in any one of paragraphs 1 to 18 arranged for removing particles from a gas stream entering the gas turbine.

21. A gas turbine as in paragraph 20 having an airflow capability of at least 1,000m per hour³Preferably greater than 4,000m per hour³More preferably more than 10,000m per hour³。

22. A gas turbine as in paragraph 20 or 21, wherein the at least one filter cassette (1) has an air flow capacity of 500 and 6,000 m/hour³In the meantime.

23. Use of a filter cassette (1) as in any of paragraphs 1 to 18 for removing particles from a gas stream entering a gas turbine.

24. Use of a filter cassette (1) according to paragraph 23 in an air intake of a gas turbine having an air flow capacity of at least 1,000m per hour³Preferably greater than 4,000m per hour³More preferably more than 10,000m per hour³。

Claims (17)

1. A filter cassette (1) for removing particles from an air stream, the filter cassette having an upstream end (14) and a downstream end (16), and comprising a mounting frame (8) for air-tight sealing with a filter medium (4) and having a mounting face (5) adapted for mounting the filter cassette to an opening of a partition (6), wherein the mounting face (5) is located between the upstream and downstream ends (14,16) of the filter cassette at a first distance (D) from the upstream end (14)_{On the upper part}) At a second distance (D) from said downstream end (16)_{Lower part}) Said first and second distances (D)_{On the upper part},D_{Lower part}) Each of which isEach accounts for more than 10 percent of the total length (L) of the filter box; said filter medium (4) comprising a plurality of filter panels (2) extending in an upstream to downstream direction, wherein said filter panels (2) are connected in an alternating manner at their upstream and downstream ends (14,16) and the side walls (10) connect adjacent filter panels (2), thereby forcing fluid flowing through the filter cassette through said filter panels; characterized in that the mounting frame (8) is hermetically sealed to the filter plate (2) in the region of the filter cassette (1) where the filter cassette is mounted to the partition (6) via the mounting face (5).

2. Filter cassette (1) for removing particles from an air flow according to claim 1, characterised in that the first and second distance (D)_{On the upper part},D_{Lower part}) Is at least 40 mm.

3. Filter cassette (1) for removing particles from an air flow according to claim 1, characterised in that the first and second distance (D)_{On the upper part},D_{Lower part}) Each of which accounts for more than 25%.

4. A filter cassette (1) for removing particles from an air stream as claimed in claim 1, wherein the mounting face (5) is located centrally of the upstream and downstream ends (14,16) with respect to the total length (L) of the filter cassette.

5. A filter cassette (1) for removing particles from an air stream as claimed in claim 1, wherein the mounting surface (5) is located on a centre of gravity line of the filter cassette with respect to the upstream and downstream ends (14, 16).

6. A filter cassette (1) for removing particles from an air stream according to claim 1, characterised in that the side walls (10) are provided upstream of the mounting frame (8) only between the downstream surface sides (18) of adjacent filter panels (2).

7. A filter cassette (1) for removing particles from an air stream according to claim 1, characterised in that downstream of the mounting frame (8) the side walls (10) are provided only between the upstream surface sides (17) of adjacent filter panels (2).

8. A filter cassette (1) for removing particles from an air stream according to claim 1, wherein the side walls (10) are provided upstream of the mounting frame (8) only between downstream surface sides (18) of adjacent filter panels (2) and downstream of the mounting frame (8) the side walls (10) are provided only between upstream surface sides (17) of adjacent filter panels (2).

9. A filter cassette (1) for removing particles from an air stream according to claim 1, wherein two outermost filter panels extend from the upstream and/or downstream end (14,16) to the mounting surface (5) and have a filter function.

10. A filter cassette (1) for removing particles from an air stream according to any of claims 1 to 9, characterised in that the filter medium (4) has a particle filtration efficiency such that the filter cassette is at least filter grade H10, according to EN1822, at 3,400 m/hour³Is less than 200 Pa.

11. A filter cassette (1) for removing particles from an air stream as claimed in claim 10, characterized by 3,400m per hour³The pressure drop under the air flow of (a) is less than 180 Pa.

12. A filter arrangement comprising a partition (6) having an opening (15) and a partition mounting face (13) surrounding said opening (15), wherein a filter cassette (1) according to any of claims 1 to 11 is mounted to said partition mounting face (13) such that the filter media (4) of the filter cassette protrudes to both sides of said partition mounting face (13).

13. A gas turbine comprising one or more filter cassettes (1) as claimed in any one of claims 1 to 11 arranged for removing particles from a gas stream entering the gas turbine.

14. The gas turbine of claim 13, having an air flow capacity of at least 1,000m per hour³。

15. Gas turbine according to claim 13 or 14, wherein at least one filter cassette (1) has an air flow capacity of 500 and 6,000 m/hour³In the meantime.

16. Use of a filter cassette (1) according to any of claims 1 to 11 for removing particles from a gas stream entering a gas turbine.

17. Use of a filter cassette (1) for removing particles from an air stream entering a gas turbine according to claim 16, characterised in that the filter cassette (1) is used in an air intake of a gas turbine with an air flow capacity of at least 1,000 m/hour³。