Field of disclosure

[0001] The present invention relates to filters and mounts for filters.

Background

[0002] Filters have been used in many applications to remove particulate matter from a fluid flowing through the filter. When filtering physical matter, a filter comprises a porous material through which the fluid can flow. Filters can be used in a variety of technological areas, from swimming pool filters to vacuum cleaners, from internal combustion engines to gas turbines.

[0003] For example, in relation to gas turbines (or ‘combustion turbines’), filters come in various different forms and are used in many different applications; such as power stations, pumps (e.g. for gas pipelines), and powering vehicles (including marine vessels, locomotives, jet propulsion in, say, aircraft). The general operation of a gas turbine is well known and involves four theoretical stages: 1) isentropic compression, 2) isobaric combustion, 3) isentropic expansion, and 4) heat rejection. Those steps in combination are also called the Brayton Cycle or the Joule Cycle.

[0004] Examples where one or more filters can be used in a gas turbine include the air intake. In the gas turbine, air is taken in and compressed, and then mixed with fuel. The mixture is then ignited (burned) to create a hot gas. That hot gas can be channelled over blades of a turbine to create rotational motion of the blades about their axis and thereby rotate the drive shaft of those blades. The rotating drive shaft can cause rotation in other members (such as generators, compressors, pumps, propellers of a marine vessel or other machinery).

[0005] Filtering the air that enters the gas turbine assists in preventing blade fouling, erosion, corrosion and asset integrity. Placing an air filter in the air intake of a gas turbine is therefore critical to the longevity, mechanical efficiency and cost efficiency of the gas turbine. [0006] While ensuring a clean air to the gas turbine is mandatory (particularly as newer gas turbines can be more sensitive to water/dust ingress), it comes at the cost of reducing the rate of flow of the fluid since the air filters provide a resistance measured as pressure drop. In a gas turbine, pressure drop through the air intake filters has a quantifiable cost, usually around 0.15% in output per lOOPa. Similar considerations apply to other uses of filters. For example, a filter is required in a swimming pool to extract debris from the water and to protect the pump.

[0007] US2019/0218970A1 discusses examples of v-shaped filters for filtering gases, including v-bank designs (e.g. Fig. 9 of US2019/0218970A1) and v-panel designs (e.g. Fig. 12 ofUS2019/0218970Al). The filters can extend to both sides of a filter wall. V- bank filter arrangements include filter cartridges that include more than one v-shaped filter element on a single flange (or header), and allow for more filter material in a given area of filter wall. Such filter cartridges can be attached to a filter wall by the flange portion of a filter frame, wherein the flange portion extends beyond the filter material to allow a point of attachment to the filter wall. The flanges to attach the filter cartridges to the filter wall therefore create areas of dead space where the gases cannot flow, thereby reducing filtering efficiency. US2019/0218970A1 further discusses the use of pins through a v-panel filter (see, e.g., Figs. 27-29 of US2019/0218970A1).

[0008] An example of a conventional v-shaped filter 1’ for a gas turbine is shown in Figs.

1 to 3. Fig. 1 shows a side view of a conventional filter 1’ mounted on a support structure 2’ that includes pins 21’ to hold the filter 1’ against a filter wall 3 of a fluid passage. Fig.

2 shows a top-down view of the filter 1’ through line A’ -A’ of Fig. 1. Fig. 3 shows a view of the conventional filter 1’ as seen from the open end 12’. Such a filter 1’ has a cavity 13’ defined by a first face 14’, a second face 15’ an end plate 16’ at a closed end

11’ of the filter and an opening at an open end 12’ of the filter 1’. The first face 14’ and the second face 15’ of the filter 1’ are closer at the closed end 11’ than at the open end 12’. Fluid passing through the opening enters the cavity 13’ and is then filtered through filter material at the first face 14’ and the second face 15’.

[0009] To connect the filter 1’ to the filter mount 3 (such as the wall of a filter chamber), a conventional arrangement includes a support structure 2’ attached to the filter mount 3. The support structure 2’ includes a mounting plate, having a hole through the middle to allow gas to pass, and two pins (also called fingers) that are attached to the wall mounting plate and that extend away from the filter mount 3. At an end opposed from the wall, the pins extend through the filter 1’ (i.e. the pins extend through the cavity 13’ to the dirty side of the filter 1’). At installation, a replacement filter 1’ has to be placed over the pins, which must then be lined up on the holes at the apex of the v-shaped filter 1 ’ through which the pins extend. A nut is then attached to the end of the rod, such that tightening the nut forces the filter 1’ along the rod and toward the filter wall 3. The installation of such a filter’ is therefore time consuming and, as the pins protrude into the fluid passage, there is a chance that engineers working in the fluid passage (to install or replace filters) could injure themselves on the pins or that the pins may catch on protective clothing. While v-shaped filters have been discussed above, similar considerations apply to cone and cylinder shaped filters that are mounted with one or more pins.

[0010] There is a need for a more efficient filter that can be quickly and accurately installed.

Means for solving the problem

[0011] The inventors have devised novel and inventive filters and mounts. A broad description will be given of specific aspects of the invention. Preferred features of the specific aspects are set out in the dependent claims.

[0012] In accordance with a preferred embodiment, a filter comprises a flange having a gas path therethrough, wherein the flange includes a first part of a detachable hook coupling operable to detachably couple to a second part of the detachable hook coupling.

[0013] According to embodiments of the present invention, the first part of the detachable hook coupling is rigid and static with respect to the flange. In some embodiments, the first part of the detachable hook coupling is an arm having a base and a hooking portion, the hooking portion being for catching on a lip of the second part of the detachable hook coupling. It is preferred that the arm includes a guide inclined between the base and a tip of the hooking portion.

[0014] In some embodiments, the first part of the detachable hook coupling is a slotted plate, the slotted plate being a plate with a slot therein. The slot has a lip with which a hooking portion of the second part of the detachable hook coupling can engage. It is preferred that the lip is tapered to a portion that will contact an arm that comprises the second part when the first part is coupled to the second part.

[0015] In certain embodiments, a filter comprises a first structure of a releasable fastening operable to connect to a second structure of the releasable fastening on the mount to bias the filter toward the mount when the first structure of the releasable fastening is connected to the second structure of the releasable fastening. In some embodiments, the first structure of the releasable fastening comprises an anchor connected to a lever by a first hinge, and a bar attached to the lever by a second hinge positioned further from the anchor along the lever than the first hinge, wherein the bar includes a catch operable to link with a catch plate of the second structure of the releasable fastening. In some embodiments, the first structure comprises a catch plate connectable to a catch of a bar of the second structure of the releasable fastening.

[0016] In some embodiments, the filter is suitable for use with a gas turbine.

[0017] In accordance with a preferred embodiment, a mount for connecting to a filter includes a second part of a detachable hook coupling operable to detachably couple to a first part of the detachable hook coupling on the filter.

[0018] According to embodiments of the present invention, the second part of the detachable hook coupling is rigid and static with respect to the mount. In some embodiments, the second part of the detachable hook coupling is an arm having a base and a hooking portion, the hooking portion being for catching on a lip of the first part of the detachable hook coupling. It is preferred that the arm includes a guide inclined between the base and a tip of the hooking portion.

[0019] In some embodiments, the second part of the detachable hook coupling is a slotted plate, the slotted plate being a plate with a slot therein wherein the slot has a lip with which a hooking portion of the first part of the detachable hook coupling can engage. It is preferred that lip is tapered to a portion that will contact an arm that comprises the first part when the second part is coupled to the first part. [0020] In certain embodiments, a mount comprises a second structure of a releasable fastening operable to connect to a first structure of the releasable fastening on the filter to bias the filter toward the mount when the second structure of the releasable fastening is connected to the first structure of the releasable fastening. In some embodiments, the second structure of the releasable fastening comprises an anchor connected to a lever by a first hinge, and a bar attached to the lever by a second hinge positioned further from the anchor along the lever than the first hinge, wherein the bar includes a catch operable to link with a catch plate of the first structure of the releasable fastening. In some embodiments, the second structure comprises a catch plate connectable to a catch of a bar of the first structure of the releasable fastening.

[0021] Embodiments of the present invention include a mount wall of an air intake for a gas turbine comprising a plurality of mounts.

[0022] Embodiments of the present invention include a system comprising a filter and a mount.

[0023] Various embodiments and aspects of the present invention are described without limitation below, with reference to the accompanying figures.

Brief description of the drawings

[0024] Fig. l is a top-down view of a conventional v-shaped filter.

[0025] Fig. 2 is a side view of a conventional v-shaped filter.

[0026] Fig. 3 is a view of a conventional v-shaped filter from the open end of that filter.

[0027] Fig. 4 is a top-down view of a plurality of filters connected to a filter wall in a gas passage.

[0028] Fig. 5a shows an end view, through an open end, of a filter according to embodiments of the present invention.

[0029] Fig. 5b shows a mount according to embodiments of the present invention.

[0030] Fig. 6a shows an end view, through an open end, of a filter according to embodiments of the present invention. [0031] Fig. 6b shows a mount according to embodiments of the present invention.

[0032] Fig. 7(a) shows a detachable hook coupling according to embodiments of the present invention in a decoupled arrangement. Fig. 7(b) shows a detachable hook coupling according to embodiments of the present invention in a coupled arrangement.

[0033] Fig. 8(a) shows a detachable hook coupling according to embodiments of the present invention in a decoupled arrangement. Fig. 8(b) shows a detachable hook coupling according to embodiments of the present invention in a coupled arrangement.

[0034] Figs. 9(a)-(c) show slotted panels of a detachable hook coupling according to embodiments of the present invention.

[0035] Figs. 10(a)-(d) show arms of a detachable hook coupling according to embodiments of the present invention.

[0036] Fig. 11 shows a releasable fastening according to embodiments of the present invention.

[0037] Figs. 12(a) and (b) show a filter connected to a mount on a mount wall according to embodiments of the present invention.

Detailed description of a preferred embodiment

[0038] The following description relates to arrangements for mounting a filter on a filter wall. A filter having a flange (also called a header herein) can be connected to a mount of a filter wall using a detachable hook coupling.

[0039] In the present specification, reference to the ‘dirty side’ of a filter 1 or filter system relates to the upstream side of the filter 1 or filter system (the side generally facing the direction from which the fluid is arriving at the filter 1) and reference to the ‘clean side’ of a filter 1 relates to the downstream side of the filter 1 (the side generally facing the direction in which the fluid leaves the filter 1).

[0040] A filter system as discussed herein comprises one or more filters 1 connected to one or more corresponding mounts 2. In the example shown in Fig. 4, eight filters 1 are shown, with corresponding mounts 2, in a gas passage. More or fewer filters 1 and corresponding mounts 2 can be provided as the situation demands. The filters 1 shown in Fig. 4 are v-shaped filters with corresponding filter mounts 2 of a filter wall 3. In Fig. 4, the mounts 4 are imbedded in the filter wall 3. In other arrangements, a plurality of mounts 2 can be connected together to create a filter wall 3. The apex of the filters 1 extends toward the opposite wall of the gas passage. The arrangement shown in Fig. 4 can be used as an air intake passage of a gas turbine, such that air passing from the intake air passage toward the gas turbine must pass through the filters 1 attached to the filter wall 3. In some arrangements, a plurality of mounts 2 can be connected together to create a filter wall 3.

[0041] The filters 1 can be detachably coupled to the corresponding mount 2 such that the filter can be quickly replaced during a maintenance procedure or quickly attached during an installation procedure. In preferred embodiments, a detachable hook coupling 5 supports the weight of the filter 1 without any movable components that bias the filter 1 toward the mount 2 (see, e.g., Figs. 4 and 12). The filter 1 for the air intake of a gas filter may weigh between 10kg and 20kg, and more typically 15kg.

[0042] A preferred filter 1 includes a flange (also termed a header) 17 with a hole 71 therethrough. The filters 1 in figures (e.g. Figs. 4, 5a-b, 6a-b and 12) are shown as v- shaped filters. It will be apparent that the present invention also applies to other types and or shapes of filter, such as pocket filters (https://www.filsonfilters.com/pocket-filters), Vbank filters, panel filters (https://www.filsonfilters.com/panel-filter), cylinders and cones cartridges, etc. that have a flange (or header). It is preferred that the flange 17 does not extend from the hole 71 further than the filter material, when present, of the filter 1. More particularly, the hole 71 of the flange 17 has a plane that passes through the flange 17 and the hole 71. The flange 17 does not extend further from the hole 71 in a direction parallel to that plane than the filter material when the filter material is mounted in the filter 1. In some preferred embodiments, the filter 1 includes a verge that extends away from the open end of the filter 1 toward the closed end to more securely hold the filter material. In such arrangements, the flange 17 does not extend away from the hole 71 (in a direction perpendicular to the plane of the hole) further than the verge.

[0043] Figs. 5a and 5b relate to a preferred embodiment in which a filter 1 can be attached to a mount 2 of a filter wall 3 using four detachable hook couplings 5 and four releasable fastenings 6. Fig. 5a shows a view through the hole 71 of a flange 17 of a filter 1. The flange 17 includes a first part 51 of one or more detachable hook couplings 5 that are operable to detachably couple to a corresponding second part 52 on a mount 2. The flange 17 further includes a first structure 61 of one or more releasable connections 6 that are operable to releasably connect to a corresponding second structure 62 of the releasable connection 6 on a mount 2. Fig. 5b shows a mount 2 that includes a second part 52 of one or more detachable hook couplings 5 that are operable to detachably couple to a corresponding first part 51 of the detachable hook coupling 5 on a filter 1. The mount 2 further includes a second structure 62 of one or more releasable connections 6 that are operable to releasably connect to a corresponding first structure 61 of the releasable connection 6 on a filter 1.

[0044] Figs. 6a and 6b relate to a preferred embodiment in which a filter 1 can be attached to a mount 2 of a filter wall using four detachable hook couplings 5 and two releasable fastenings 6. The flange 17 of the filter 1 as shown in Fig. 6a includes the first part 51 of four detachable hook couplings 5 and the first structure 61 of two releasable fastenings 6. The mount 2 as shown in Fig. 6b includes the corresponding second part 52 of the four detachable hook couplings 5 and the corresponding second structure 62 of the two releasable fastenings 6.

[0045] In some arrangements, the first part 51 may comprise an arm 53 with a hooking portion 55 and the second part 52 comprises a slotted panel 54, and in other arrangements, the first part 51 comprises a slotted panel 54 and the second part 52 comprises an arm 53 with a hooking portion 55 (see, e.g., Figs. 7-10). In some arrangements, the first structure 61 is a static structure 6a, in which no parts move relative to a base (or catch plate) 69, and the second structure 62 is an adjustable structure 6b in which at least one part is movable relative to an anchor 63 (see, e.g., Fig. 11), and in other arrangements the first structure 61 is an adjustable structure 6b and the second structure 62 is a static structure 6b.

[0046] When coupled to the mount 2, the flange 17 is the closest part of the filter 1 to the mount 2. The flange 17 has an opening 71 therethrough to allow fluid to pass through the flange 17. When the filter 1 is attached to the mount 2, the hole 71 in the flange 17 aligns with a hole 72 in the mount 2. A gas path therefore passes through both the hole 72 in the mount 2 and the hole71 in the flange 17 of the corresponding filter 1.

[0047] As discussed above, in the preferred arrangement, a filter 1 includes a first part 51 of a detachable hook coupling 5, where the first part 51 is operable to couple to a second part 52 on a mount 2. The filter 1 may contain the first part 51 of a plurality of detachable hook couplings 5, each operable to couple to a corresponding second part of the detachable hook coupling 5 associated with the corresponding mount 2. The first part 51 of the detachable hook coupling 5 is preferably part of the flange 17 of the filter 1. The first part 51 is preferably on a portion of the flange 17 that faces the mount 2 and the second part 52 is preferably on a portion of the mount that faces the flange 17. The detachable hook coupling 5 does not require additional space on the filter wall, and filters 1 can be positioned closer together, thereby increasing the amount of filter material associated with the filter wall as a whole.

[0048] The detachable hook couplings 5 are able to support the weight of the associated filter 1 to hold the filter against the mount 2. In the preferred embodiment, the first part 51 and the second part 52 of a detachable hook coupling 5 are rigid. For example, the first part 51 and the second part 52 do not include hinges or flexible portions. Similarly, the first part 51 is static in relation to the flange 17 (i.e. there is no relative movement between the first part 51 and the flange 17) and the second part 51 is static in relation to the mount 2 (i.e. there is no relative movement between the second part 52 and the mount 2). The rigid and static nature of the first part 51 and second part 52 allows for a robust detachable hook coupling 5, and allows the filter 1 to be coupled to the mount 2 in a more reliable and predictable manner, thereby allowing a filter 1 to be quickly installed over a gas opening associated with the mount 2.

[0049] A side view of a detachable hook coupling 5 according to preferred embodiments can be seen in the arrangements shown in Figs. 7 and 8. The detachable hook coupling 5 is uncoupled in Figs. 7(a) and 8(a), and coupled in Figs. 7(b) and 8(b). The first part 51 of the detachable hook coupling 5 comprises an arm 53 and the second part 52 of the detachable hook coupling 5 comprises a slotted panel 54. In other arrangements, the first part 51 comprises the slotted panel and the second part 52 comprises the arm. [0050] The arm 53 has a base 56 that is affixed to the filter 1 or the mount 2. The slotted panel 54 is associated with the other of the filter the mount (i.e. if the arm 53 is attached to the filter 1, the slotted panel 54 will be associated with the mount and if the arm 53 is attached to the mount the slotted panel 54 will be associated with the filter). The arm 53 has a hooking portion 55 at a point remote from the base 56. In Figs. 7(a) and 7(b), the hooking portion 55 extends upwards, in Figs. 8(a) and 8(b) the hooking portion 55 extends downward. The arrangement of Figs. 7(a) and 7(b) is more suitable for situations in which the arm 53 is attached to the filter 1 and the slotted panel 54 is on or part of the mount 2. The arrangement of Figs. 8(a) and 8(b) is more suitable for situations in which the arm 53 is attached to the mount 2 and the slotted panel 54 is on or part of the filter 1. Examples of a slotted panel 54 are shown in Figs. 9(a)-(c).

[0051] When attached to the slotted panel 54, as in Figs. 7(b) and 8(b), the hooking portion 55 of the arm 53 will engage with a lip 59 of the slot 58 of the slotted panel 54 to limit movement of the flange 17 away from the mount 2. When the detachable hook coupling 5 couples a filter 1 to a mount 2, the weight of the filter 1 presses the arm 53 against the lip 59 of the slot 58 in the slotted panel 54, such that the hooking portion 55 is on one side of the panel 54 and the base 56 is on the other side of the panel 54, with the arm 53 in contact with the lip 58 of the slot 58. The hooking portion 55 opposes a movement of the filter 1 away from the mount 2. In Figs. 7(b) and 8(b), the hooking portion 55 prevents the element to which the arm 53 is attached from moving laterally away from the slotted panel 54 (i.e. the horizontal movement in Figs. 7(b) and 8(b) is opposed).

[0052] By using one or more detachable hook couplings 5 to couple a filter 1 to a mount 2, the filter 1 may be installed quickly and easily, thereby reducing the downtime for the system (such as a gas turbine system) to which the filter 1 is connected. Further, using a detachable hook coupling between the flange 17 of a filter 1 and the associated mount 2 allows the side of the filter 1 opposed to the flange 17 to extend further away from the mount 2. The increase in size of the filter 1 in turn allows for additional filter material to be included with the filter 1, thereby increasing overall filter efficiency for a filter system as a whole. For example, filters 1 can be mounted to a filter wall 3 in the air intake passage of a gas turbine. In such an air intake passage, a wall 4 opposite the filter wall 3 can hinder installation and replacement of the filter 1 as the filter 1 needs initially to be placed over the pins of the support frame where the pins have to be long enough to extend through the filter 1 for connection. With the flange 17 of the filter 1 including first part of a detachable hook coupling 5 that is operable to detachably connect to a second part 52 of the detachable hook coupling on the mount 2, there is no need for pins that are long enough to extend through the filter 1. The filter 1 therefore does not require as much additional space past the ends of the pins for installation, and that additional space can be used to increase the size of the filter 1, and thereby to add additional filter material.

[0053] In addition, as the pins are not needed, the sheets of filter material of the filter 1 can be brought closer together, thereby improving the efficiency of the filter 1. In a conventional v-shaped filter 1’, as shown in Figs. 1-3, the first face 14’ and the second face 15’ are closest at the end panel 16’. As can be seen in Fig. 3, the size of the end panel 16’ of the conventional filter 1’, in a direction between the first face 14’ and the second face 15’, is limited by the diameter of the pins (also called ‘fingers’) of the support frame to which the conventional filter 1’ is to be attached. Sheets of filter material mounted in the conventional filter 1 ’ are therefore spaced at least by the diameter of the fingers.

[0054] As the pins are not present, the spacing between the sheets of filter material is not constrained by the diameter of the pins and so the sheets of filter material can be brought close together at the closed end 11 of the filter, as can be seen in Figs. 12(a) and (b). In an example where fluid flow passes through the filter material before entering the cavity 13 (i.e. the cavity is downstream of the filter material), an area of high pressure will be generated at the end plate 16 (and any connection plate) as fluid cannot flow therethrough and will be forced to change direction before flowing along the first or second face of the filter 1. The fluid that has changed direction before flowing along the first face 14 or second face 15 will mix with the fluid that is directly incident on the first face 14 or second face 14, and will lower the velocity thereby increasing the distance from the first face 14 or second face 15 to an area of laminar flow of the fluid. As a larger end panel causes a larger area of high pressure, the volume of fluid changing direction will be greater, the laminar flow will be more remote from the first or second face 14, 15 and the force of the fluid on the sheets of filter material will be reduced and the rate of fluid passing through the sheets of filter material will be reduced. The larger the gap between the sheets of filter material 141, 151 at the apex of the filter, therefore, the greater the pressure drop. As there are no pins extending through the filter 1, the filter media can be closer together at the narrow end 11 of the filter 1, thereby mitigating the pressure drop. Such a filter 1 arrangement therefore reduces emissions, and lowers gas consumption. When mounted to the air inlet of a gas turbine, this leads to an improvement in gas turbine output by reducing the inefficiency caused by the inlet pressure drop.

[0055] One or more detachable hook couplings 5 can also be applied to V-bank filter arrangements. Instead of a flange of a filter cartridge extending beyond the filter material to provide a point of attachment as in US2019/0218970A1, the first part 51 of one or more detachable coupling 5 can be included on a face of the header that will face the mount when the filter cartridge is coupled to the mount. The corresponding second part 52 of the detachable coupling 5 is included with the mount. The flange therefore doesn’t need to extend beyond the filter material (i.e. beyond a line drawn around the open end of the filter elements of the filter cartridge) to provide a point of attachment, and so the amount of dead space is reduced. In some arrangements, the flange includes a verge that extends away from the open end of the filter elements toward the closed end to more securely hold the filter material. In such arrangements, the flange does not extend further than the verge.

[0056] Figs. 9 (a)-(c) show a view of three different slot 58 shapes. In each of Figs. 9(a)- (c), the hooking portion 55 of the arm 53 can extend through the slot (or hole) 58 of the slotted plate (or slotted panel) 54. For example, when installing the filter 1, the filter 1 may be aligned with the mount 2 such that the hooking portions 55 can pass through the corresponding slots 58. When the hooking portion 55 has extended through the slot 58, the weight of the filter 1 brings the arm 53 into contact with the lip 59 of the slot 58. The hooking portion 55 of the arm 53 therefore engages with the lip 59 of the slot 58, and movement of the slotted panel 54 away from the panel to which the arm 53 is attached is countered (e.g. in in Figs. 7(b) and 8(b), the lateral movement of the panels as prevented). In the arrangement shown in Fig. 9 (a), the slot 58 is uniform and is therefore simple to manufacture. A slotted plate 54 having a slot 58 as shown in Fig., 9(a) can be used as the first part 51, associated with a flange 17 of a filter 1, or the second part 52, associated with a mount 2, of a detachable hook coupling 5. The arm 53 will contact the lip 59 at the top or at the bottom of the slot 58 depending on whether the slotted plate 54 is associated with the mount 2 or the flange 17. The slots 58 in Figs. 9(b) and (c) taper from a wide section, where the hooking portion 55 will pass through, to a narrow section where the arm 53 will rest against the lip 59 when the first part 51 and the second part 52 of the detachable hook coupling 5 are coupled together. Tapering the slot 58 allows the arm 53 to be more predictably located in relation to the slot 58 as the weight of the filter 1 causes the arm 53 to move, relative to the slot 58, from the wide section to the narrow section. A filter 1 can therefore be quickly and accurately coupled to the mount 2. The slot arrangement of Fig. 9(b) is most preferably used when the slotted plate 54 is associated with the mount 2. The weight of the filter 1 will cause the arm 53 to contact the lip 59 at the bottom of the slot 58 after the hooking portion 55 has been pushed through the slot 58. The slot arrangement of Fig. 9(c) is most preferably used when the slotted plate 54 is associated with the flange 17. The weight of the filter 1 will cause the arm 53 to contact the lip 59 at the top of the slot 58 after the hooking portion 55 has been pushed through the slot 58.

[0057] The arm 53 can be different shapes, as shown in Fig. 10. In the arrangements of Figs. 10 (a)-(c), the arm 53 includes a guide 53a between the tip 55a of the hooking point 55 and an apex that will rest against the lip 59 of the slot 58 when the arm 53 is coupled to the slotted plate 54. Preferably, the apex is at the base 56 of the arm 53 to ensure a tight seal. The guide 53a assists in accurately positioning the filter 1 against the mount 2 when coupling the detachable hook coupling 5. The guide 53a in Figs. 10(a)-(c) is slanted (or angled) relative to the largest extension of the arm 53. In an example when the arm 53 is attached to the filter 1, the guide 53a will extend downwards from the apex and away from the filter 1 towards the tip 55a of the hooking portion 55. The tip 55a of the hooking portion 55 will therefore be lower than the apex when the filter 1 is coupled to the mount 2. The arm shapes shown in Figs. 10(a)-(c) correspond to the arm 3 arrangement as shown in Fig. 7. It will be apparent that equivalent shapes can be applied to the arm arrangement as shown in Fig. 8. In an example when the arm 53 is attached to the mount 2, the guide 53a will extend upwards from the apex and towards the tip 55a of the hooking portion 55. The tip 55a of the hooking portion 55 will therefore be lower than the apex when the filter 1 is coupled to the mount 2. The weight of the filter 1 therefore biases the filter 1 toward the mount 2, thereby improving the seal between the filter 1 and the mount 2.

[0058] Fig. 10(d) shows an arm structure in which the hooking portion 53 extends upwards and downwards. The hooking portion 55 has two tips 55a, both of which will be on a different side of the slotted panel 54 than the base 56 when the detachable hook coupling 5 is coupled. Such an arrangement can simplify manufacturing in scenarios where it is not known in advance if the arm 53 will be attached to the filter 1 or the mount 2.

[0059] It will be appreciated that the hooking portion 55 may include a section broader than the guide 53a. For example, the edge of the arm 53 furthest away from the base 56 can be broader than the guide 53a but smaller than the breadth of the slot 58 of the detachable hook coupling 5. When the slot 59 tapers, such as in the arrangements of Figs. 9(b) and (c), as the edge remote from the base 56 is broader, the arm 53 and the slotted panel 54 can be coupled more securely.

[0060] To further improve the seal, one or more releasable fastenings 6 may be included to bias the filter 1 toward the mount 2. For example, one or more detachable couplings 5 support the weight of the filter 1, and one or more releasable fastenings can pull the filter 1 toward the mount 2 to create a better seal between the filter 1 and the mount 2. In some arrangements, one or more of the releasable fastenings 6 is a toggle clamp. As shown in Fig. 5a, the first structure 61 of a releasable fastening 6 is associated with the flange 2 and, as shown in Fig. 5b, the second structure 62 of the releasable fastening 6 is associated with the mount 2. The first structure 61 of a releasable fastening 6 is connectable to a second structure 62 of the releasable fastening 6 included with the mount 2. The first structure 61 is on a portion of the flange 17 that forms an edge of the hole through the flange 17. The portion of the flange 17 on which the first structure 61 is located therefore faces another portion of the flange 17. The first structure 61 and the second structure 61 of the releasable fastening 6 meet and can be releasably connected when the one or more detachable hook couplings 5 associated with the filter 1 and the mount 2 are coupled. [0061] An example of a releasable fastening 6 is shown in Fig. 11. The releasable fastening 6 comprises an anchor 63 connected to a lever 64 by a first hinge 65. A bar 66 is attached to the lever 64 by a second hinge 67 positioned further from the anchor 62 along the lever 64 than the first hinge 65. The bar 66 includes a catch 68 (such as a loop or a claw) that can link with (or catch on) the catch plate 69. When the lever 64 is in a first position, the bar 66 can reach further away from the anchor 63 than when the lever 64 is in a second position. In operation, the lever 64 is placed in the first position, and the catch 69 catches the catch plate 69. The lever 64 is then moved to the second position. The action of moving the lever 64 to the second position draws the catch plate 69 closer to the anchor 63. For example, in the arrangement of Fig. 11, the catch plate 69 includes a protrusion such that the catch 68 can link with the catch plate 69 by at least part of the catch 68 being located on a side of the protrusion remote from the anchor 63. When the lever 64 is moved to the second position, the part of the catch 68 on the side of the protrusion remote from the anchor 64 pulls against the protrusion, thereby biasing the catch plate 69 closer to the anchor 63. When the anchor 63 and the catch plate 69 are attached to a flange 17 of a filter 1 and a corresponding mount 2, moving the lever 64 to the second position biases the flange 17 toward the mount 2.

[0062] The releasable fastening 6 is operable from the cavity side of the v-shaped filter 1. Typically, this is the downstream (or ‘clean’) side of the filter 1. When the filter 1 is used in the air intake of a gas turbine, the releasable fastening 6 can be accessed through a hole through an adjacent mount 2 that is yet to have a filter 1 attached. The releasable fastening could also be accessed via maintenance access panels to the clean side of the filter wall 3 of which the mounts 2 are a part.

[0063] By providing a releasable fastening 6 accessible from the clean side of the filter 1, installation and replacement of a filter 1 is more efficient. For example, filters 1 can be mounted to a filter wall 3 in the air intake passage of a gas turbine. In such an air intake passage, the wall opposite the filter wall 3 can hinder installation and replacement of a conventional filter (e.g. Figs. 1-3), which needs initially to be placed over the pins of the support frame. The combination of the dimensions of the air intake passage and the pins of the support frame therefore limits the size of the filter as the filter 1 must be small enough to fit over the pins during installation. [0064] In arrangements with the releasable fastenings 6, the weight of the filter is borne mainly by the detachable hook couplings 5 with the releasable fastenings pulling the filter 1 toward the mount for a more effective seal. Different numbers and locations of detachable hook couplings 5 and releasable fastenings 6 can be included depending on circumstance as long as a first part 51 of each detachable hook coupling 5 on a filter corresponds to a second part 52 of a detachable hook coupling 5 on a mount 2 and a first structure 61 of a releasable fastening 6 corresponds to a second structure 62 of a releasable fastening 6 on the mount 2. In some embodiments, the mount 2 includes the second part 52 of two detachable hook couplings 5 at the top of the mount 2 (i.e. near the highest part of the mount 2 or touching the highest edge of the mount 2). A corresponding filter 1 can have the corresponding first parts 51 of the detachable hook couplings 5. When the filter 1 is connected to the mount 2, the detachable hook couplings 5 support the weight of the filter 1 toward the top of the filter 1. The lower end of the flange 17 of the filter 1 can then be secured to the lower end of the mount 2 using a releasable fastening 6. The number of releasable fastenings 6 is thereby minimised and the time to install or replace a filter 1 is reduced. In addition, even though the releasable fastenings 6 have less of an impact on the gas flow in the cavity than the pins (or fingers) of conventional arrangements, minimising the number of releasable fastenings 6 reduces the impact on gas flow through the filter 1.

[0065] In another example, a releasable fastening 6 can comprise a strap fixed to an anchor 63, with a bar attached to a plate 69. When the anchor 63 is affixed to the filter 1, the plate 69 is affixed to the mount 2. When the anchor 63 is fixed to the mount 2, the plate 69 is affixed to the filter 1. The two parts of the releasable fastening 6 can be coupled by passing the strap around the bar and pulling the strap tight, before securing the strap in place.

[0066] In some arrangements, the releasable fastening 6 includes a ratchet to pull the filter 1 against the mount 2. If materials used to form the mount 2 or filter 1 distort or soften over time, the ratchet can compensate by allowing the seal between the filter 1 and the mount 2 to be tighter. Similarly, if a gasket is provided between the filter 1 and the mount 2, the gasket may compress during a first use such that a replacement filter 1 (i.e. after the first filter is removed and replaced) must be pulled further toward the mount 2 if the same gasket is to be reused.

[0067] A gasket can be provided between the filter 1 and the mount 2 to provide a better seal. For example, through use, a mount 2 may become slightly distorted. A filter 1 attached to the mount 2 during the distortion may also distort in the same manner, thereby maintaining an adequate seal. When a replacement filter 1 is installed, however, a slight distortion to the mount 2 may be detrimental to forming an adequate seal with the replacement filter 1. A gasket accounts for those slight distortions. The gasket can be constructed of compressed fibres, plastic (such as polytetrafluoroethylene, PTFE, or polychlorotrifluoroethylene), or metal (such as copper).

[0068] It is preferred that the one or more filters 1 are v-shaped filters, as shown in Figs. 12(a) and 12(b). Fig. 12(a) shows an arrangement in which a first part 51 of the detachable hook coupling 5 (such as an arm 53 shown in Fig. 10) extends into the second part 52 of the detachable hook coupling 5 (such as a slotted panel shown in Fig. 9). Fig. 12(b) shows an arrangement in which a second part 52 of the detachable hook coupling 5 (such as an arm 53 shown in Fig. 10) extends into the first part 51 of the detachable hook coupling 5 (such as a slotted panel shown in Fig. 9). It will be apparent that the present invention is applicable to other types of filters. For example, cone filters and cylindrical filters can conventionally be connected to a filter wall by one or more pins similarly to the v-shaped filter shown in Figs. 1-3. Detachable hook couplings as described herein can be used instead of the pins to allow for faster and safer installation and replacement of the filters. As well, releasable fastenings as described herein can be used to improve the seal between the filter and a mount to which the filter is attached.

[0069] A v-shaped filter 1 comprises a first face 14 and a second face 15. Each of the first face 14 and second face 15 has an associated sheet of filter material. The sheets of filter material are preferably pleated to increase the surface area of the sheet of filter material such as a pleat pack. The first face 14 and the second face 15are closer at the closed end 11 than at the open end 12 such that the first face 14 and the second face 15, and hence the associated sheets of filter material, form a V-shape when viewed from the top, as shown in Figs. 12(a) and 12(b). The distance between the first face 14 and the second face 15 increases as it moves away from the closed end 11 toward the open end 12, thereby creating a cavity 13 in the filter 1.

[0070] The first face 14 and the second face 15 are preferably both quadrilaterals, and more preferably are generally rectangular in shape (wherein rectangular comprises four sided quadrilaterals with right-angle corners). In Figs. 12(a) and 12(b), the first face 14 and the second face 15 contact each other at the closed end 11 of the filter 1. A flange 17 is provided at the open end 12 of the filter 1. The flange 17 has an opening therethrough to allow fluid to pass through the flange 17 and into the cavity 13, or for fluid to pass out of the cavity 13 through the flange 17 depending on the direction of fluid flow. Other filter shapes with a flange to allow fluid to pass through the filter 1 are possible.. For example, a filter 1 can be a box filter where the sides that extend away from the flange are parallel.

[0071] In a preferred arrangement, the flange 17 includes the first part 51 of four detachable hook couplings 5 spaced around the flange 17. A corresponding mount 2 has corresponding second parts 52. In the arrangement shown in Figs. 5 and 6, the first parts

51 are provided near four corners of a quadrilateral shaped flange 17 and the second parts

52 are provided near four corners of a quadrilateral shaped mount 2. Other positions of the first parts 51 of the detachable hook couplings 5 on the flange 17 are possible and other positions of the second parts 52 of the detachable hook couplings 5 on the mount 2 are possible. It will also be apparent that more or fewer detachable hook couplings 5 can be used to detachably couple the filter 1 to the mount 2.

[0072] In the arrangement shown in Fig. 5a, the flange 17 includes the first structure 61 of four releasable fastenings 6. The arrangement of Fig. 5b shows a corresponding mount 2 with the second part 62 of the four releasable fastenings 6. In other arrangements, more or fewer releasable fastenings 6 are provided to bias the filter 1 toward the mount 2. For example, in some arrangements, the flange 17 has the first part 61 of two releasable fastenings 6. In such arrangements, the first part 61 of one releasable fastening 6 can be at the top of the flange 17 and the first part 61 of the other releasable fastening 6 can be at the bottom of the flange 17. Similarly, in corresponding arrangements, the second part 62 of one releasable fastening 6 can be at the top of the mount 2 and the second part 62 of the other releasable fastening 6 can be at the bottom of the mount 2. Having fewer releasable fastenings 6 reduces the amount of time required to replace and/or install a filter 1.

[0073] In some arrangements, the releasable fastenings 6 and the detachable hook couplings 5 can be positioned to compliment each other. For example, in the arrangement shown in Fig. 5a, the first parts 61 of the four releasable fastenings 6 are positioned to draw the corners of the flange 17 toward the mount 2. Other arrangements include two detachable hook couplings 5 and one releasable fastening 6. For example, a flange 17 may include the first part 51 of two detachable hook couplings 5 located at a top of the flange 17 and a first structure 61 of a releasable fastening 6 at the bottom of the flange 17. The filter 1 will be supported by the detachable hook couplings 5 at the top of the flange 17. The detachable hook couplings 5 bias the top of the flange 17 toward the mount 2. The releasable fastening 6 will bias the bottom of the flange 17 toward the mount 2. Such an arrangement allows for quick replacement/installation of the filter 1 while allowing an adequate seal between the filter 1 and the mount 2.

[0074] Many other variants and embodiments will be apparent to the skilled reader, all of which are intended to fall within the scope of the invention whether or not covered by the claims as filed. Protection is sought for any and all novel subject matter and combinations thereof disclosed herein.