Filter apparatus

Abstract

A filter apparatus (1) for separating dust particles from a gas mixture, comprising – a filter housing (2) and - at least one support tube (3) rotatably mounted in the filter housing (2) and - at least one cylindrical filter element (4) that can be rotated with the support tube (3) and - at least one drive (5) for rotating the support tube (3) and the filter element (4), wherein the filter element (4) can be cleaned off just by means of the centrifugal forces generated by rotation of the filter element (4) with the support tube (3).

Description

[0001]

[0002] filter device

[0003] The present invention relates to a filter device for separating dust particles from a gas mixture, comprising a filter housing, and at least one support tube rotatably mounted in the filter housing, and at least one cylindrical filter element rotatable with the support tube, and at least one drive for rotating the support tube and the filter element.

[0004] Furthermore, the invention relates to a method for operating a filter device of the type mentioned.

[0005] Such filter devices can be called fabric filters, dry filters, or bag filters. They are used to purify a gas or gas mixture, hereinafter generally referred to as a gas mixture, whereby dust particles are separated or captured from the gas mixture by means of a filter element. Such a gas mixture can, for example, be a combustible product gas produced by gasification, e.g., from biomass or a mixture of biomass and plastic.

[0006] In practice, a filter system for separating dust particles from a gas mixture usually consists of two or more filter devices connected in parallel, i.e. arranged next to one another.

[0007] The cleaning of the gas mixture by means of such a filter device takes place in that the gas mixture flows through at least one filter element, whereby the dust particles contained in the gas mixture adhere to an inflow side of the filter element and are thus separated from the gas mixture.

[0008] This also means that the gas mixture flows as so-called raw gas to one surface of the filter element and further through the filter element, and leaves the filter element as clean gas at a second surface.

[0009] The dust particles accumulate on the surface of the filter element and generate a layer of dust particles, the so-called filter cake. The filter cake grows over time and increasingly clogs the filter element, causing its functionality to decrease over time. In other words, this means that the filter element has a limited service life.

[0010] In order to maintain the filter function of the filter device and to extend the service life of a filter element, it is common practice to clean the filter element from time to time.

[0011] For example, cleaning methods using scrapers for scraping the filter element are known from the prior art. For example, EP 3 492 161 A1 shows a filter device with two scrapers arranged next to two cylindrical filter elements. In a cleaning state of this filter device, the two filter elements rotate about their longitudinal axis, rubbing their outer surfaces along the two scrapers, whereby dust accumulated on the filter elements is scraped off and falls to the ground.

[0012] While this cleaning method can extend the service life of the filter elements, it also exposes them to significant mechanical stress due to the wiping process. This mechanical stress, or regular abrasion, has a significant adverse effect on the service life of the filter elements.

[0013] The object of the present invention is therefore to provide a filter device of the type mentioned at the outset which is improved compared to the prior art.

[0014] This problem is solved by the features of patent claim 1.

[0015] It is therefore provided in filter devices according to the invention that the at least one filter element can be cleaned exclusively by means of the centrifugal forces generated by rotation of the filter element with the support tube.

[0016] The major advantage of this filter device is that at least one filter element is not subjected to any mechanical stress or abrasion caused by a scraper. This can significantly increase the service life of the filter element.

[0017] This means that the filter element can be cleaned and reused as needed with a very high, advantageously almost unlimited, number of cleaning processes. It should be noted that the cleaning processes advantageously take place during a cleaning state of the filter device, whereby the cleaning state is different from the filtering state.

[0018] When the filter device is in filtering mode, the support tube and the filter element are preferably in a stationary or nearly stationary state. Therefore, in the filtering mode, no centrifugal forces act on the filter element.

[0019] In the cleaning state, the drive rotates the support tube to which the filter element, which can rotate with the support tube, is attached, so that centrifugal forces are created on the filter element, by which dust particles adhering to the filter element are loosened, so that the filter element is cleaned.

[0020] The at least one filter element is advantageously cylindrical and / or tubular.

[0021] During filtration, the gas mixture flows as raw gas from the outer surface to the inner surface of the filter element, with the dust particles being separated at the filter element. From the inner surface of the filter element, it then flows further as clean gas. The dust particles collect on the outer surface of the filter element.

[0022] During cleaning, the centrifugal forces generated by rotation can reverse the flow direction of the gas mixture, causing the clean gas to flow from the inner surface to the outer surface of the filter element. Preferably, the longitudinal axis of the support tube is a vertical axis when the filter device is in operation, so that when the support tube rotates about its longitudinal axis, the dust particles released from the filter element can fall unhindered along the outer surface of the filter element, i.e., in the space between the filter element and the filter housing, to the bottom of the filter housing.

[0023] The support tube can also be called a support shaft.

[0024] The filter element can also be called a filter hose.

[0025] Further advantageous embodiments of the invention are defined in the dependent claims.

[0026] It is particularly preferred that the filter element is rotatable by the drive at a minimum tangential speed on an outer surface of the filter element of 20 m / s for cleaning the filter element.

[0027] The drive can be conveniently controlled or regulated using a control or regulating unit.

[0028] It is particularly preferred that the filter device comprises two circular, gas-impermeable support discs, which are aligned orthogonally to the longitudinal direction of the support tube and secured to the support tube at a distance from one another, and are rotatable with the support tube by the drive, to which the filter element is attached, preferably by means of clamps. The preferably fabric-like filter element is advantageously stretched onto the gas-impermeable support discs.

[0029] In addition to clamps, other fastening means are also possible for fastening and / or clamping the filter element to the gas-tight support discs.

[0030] Preferably, the fastening of the filter element to the gas-impermeable support discs is designed to be flow-tight, so that no fluid flow or gas mixture and / or clean gas flow takes place in the connection area between the filter element and the gas-impermeable support discs.

[0031] This means that the gas mixture preferably flows exclusively through the filter element.

[0032] The support tube or the support shaft, the two gas-impermeable support discs and the filter element advantageously form together a so-called filter drum, which can be rotated in its entirety by the drive.

[0033] It is also possible that several rotatably mounted filter drums that can be rotated by at least one drive are arranged within a filter housing.

[0034] In the filtering state of the filter device, the gas mixture preferably flows from the space between the outer surface of the at least one filter drum and the filter housing into the interior of the at least one filter drum and then toward the at least one support tube. It is particularly preferred that the at least one support tube has a plurality of gas inlet openings on its outer surface in the region between the gas-impermeable support discs and at least one gas outlet opening at one end of the support tube for discharging the clean gas, i.e., the purified gas mixture.

[0035] In the area of ​​the gas outlet opening of the support tube, a rotary union can be arranged, which directs the clean gas flowing from the gas outlet opening into a clean gas outlet opening, where it leaves the filter device.

[0036] It is particularly preferred that the filter housing has at least one gas supply opening which is designed to supply the gas mixture to be filtered into the filter housing.

[0037] Particularly preferably, at least one, preferably channel-shaped, dust collection housing is arranged under the filter housing, which has at least one raw gas supply opening for supplying the gas mixture to be filtered into the dust collection housing, and at least one raw gas overflow opening which is congruent with the gas supply opening of the filter housing for supplying the gas mixture to be filtered from the dust collection housing into the filter housing, wherein the raw gas overflow opening is at the same time a dust removal opening for removing the dust separated by the filter element from the filter housing into the dust collection housing.

[0038] Advantageously, the raw gas overflow opening is arranged at a distance from the raw gas supply opening. This measure ensures that larger dust particles can fall to the bottom of the dust collection housing before entering the filter housing through the gas supply opening, leaving only smaller, lighter dust particles to pass into the filter housing with the gas mixture to be filtered out by the filter element. In this context, it is advantageous if the distance between the raw gas overflow opening and the raw gas supply opening is at least as large as the diameter, in particular the largest diameter, of the raw gas supply opening. It is also advantageous in this context if an opening plane of the raw gas supply opening is angled, preferably orthogonal, to an opening plane of the raw gas overflow opening.

[0039] It is preferably provided that the dust collection housing has at least one dust lock for discharging the separated dust from the dust collection housing, and / or at least one transport screw rotatable by means of a transport screw drive for transporting the separated dust within the dust collection housing.

[0040] The dust lock is advantageously designed to be flow-tight so that no fluid flow through the dust lock takes place at least when the separated dust is not being discharged.

[0041] The transport of the separated dust, preferably by means of the transport screw, is advantageously carried out in the direction of at least one dust lock.

[0042] The separated dust can also be transported by means of an alternative transport means, such as by means of at least one scraper, pusher, conveyor belt or the like.

[0043] It is preferably provided that the filter device for stiffening and / or suspending the filter element has at least one circular gas-permeable support disc fastened to the support tube and to the filter element, for example by means of clamps, brackets, screws or other fastening means, and arranged at a distance between the gas-impermeable support discs and aligned orthogonally to the longitudinal direction of the support tube.

[0044] The gas-permeable support discs are primarily used to maintain the cylindrical shape or to stiffen the filter element.

[0045] Protection is also sought for a method for operating a filter device according to the invention, wherein the filter element of the filter device with the support tube is rotated to clean the dust from the filter element exclusively by means of centrifugal forces, preferably with a minimum tangential speed on an outer surface of the filter element of 20 m / s.

[0046] The method for operating a filter device according to the invention relates in particular to the cleaning state of the filter device.

[0047] Further advantages and details of the invention will become apparent from the accompanying figures and descriptions. These show:

[0048] Fig. 1 shows a first embodiment of a filter device according to the invention, Fig. 2 shows a second embodiment of a filter device according to the invention, Figs. 3 and 4 show two horizontal sections through the filter device of the first and / or second embodiment, and

[0049] Fig. 5 shows a third embodiment of a filter device according to the invention.

[0050] Fig. 1 shows a schematic vertical section of a first embodiment of a filter device 1 according to the invention for separating dust particles from a gas mixture.

[0051] The filter device 1 comprises a filter housing 2, at least one support tube 3 rotatably mounted in the filter housing 2, at least one cylindrical filter element 4 rotatable with the support tube 3, and at least one drive 5 for rotating the support tube 3 and the filter element 4, wherein the filter element 4 can be cleaned exclusively by means of the centrifugal forces generated by rotation of the filter element 4 with the support tube 3, preferably with a minimum tangential speed on an outer surface of the filter element 4 of 20 m / s.

[0052] The exemplary embodiment of a filter device 1 according to the invention shown in Fig. 1 comprises two circular, gas-impermeable support disks 6 which are aligned orthogonally to the longitudinal direction of the support tube 3 and fastened to the support tube 3 at a distance from one another and can be rotated with the support tube 3 by the drive 5, to which support disks the filter element 4 is fastened, preferably by means of clamps, preferably tensioned. In this exemplary embodiment, two gas inlet openings 7 are shown along the outer surface of the support tube 6 in the area between the gas-impermeable support disks 6, and at one end of the support tube there is a gas outlet opening 8 for the removal of gas mixture purified by the filter element 4, or in other words clean gas.

[0053] The filter device 1 can generally have any number of gas inlet openings 7 and / or gas outlet openings 8.

[0054] In this embodiment, the filter housing 2 has at least two gas supply openings 9 which are designed to supply the gas mixture to be filtered into the filter housing 2.

[0055] In this embodiment, a preferably channel-shaped dust collection housing 10 is arranged below the filter housing 2, which has at least one raw gas supply opening 11 for supplying the gas mixture to be filtered into the dust collection housing 10.

[0056] Furthermore, the dust collection housing 10 has two raw gas overflow openings 12 which are congruent with the gas supply opening 9 of the filter housing 2 for supplying the gas mixture to be filtered from the dust collection housing 10 into the filter housing 2, wherein the two raw gas overflow openings 12 are simultaneously two dust discharge openings for discharging the dust separated by the filter element 4 from the filter housing 2 into the dust collection housing 10.

[0057] In this first embodiment, it can be seen that the left raw gas overflow opening 12 is also arranged at a distance from the raw gas supply opening 11, so that larger, heavier dust particles fall into the dust collection housing 10 before the gas mixture enters the filter housing 2.

[0058] Therefore, a gas mixture which at least predominantly contains only smaller, lighter dust particles is advantageously supplied to the filter element 4.

[0059] It is also possible for the filter device 1 to have exactly one or more than two gas supply openings 9 and / or raw gas overflow openings 12.

[0060] In this embodiment, the dust collection housing 10 has at least one dust lock 13 for discharging the separated dust from the dust collection housing 10 and / or at least one transport screw 15 which can be rotated by means of a transport screw drive 14, i.e. a drive of any design, for transporting the separated dust within the dust collection housing 10.

[0061] In Fig. 1, the direction of movement of the gas mixture 17 and the direction of movement of larger dust particles 18, particularly within the dust collection housing 10, are indicated by arrows. It can be seen that the gas mixture with smaller, lighter dust particles initially flows essentially from bottom to top, or rises from the dust collection housing 10 into the filter housing 2, and that larger, heavier dust particles and / or the separated filter cake fall from top to bottom into the dust collection housing 10 due to gravity.

[0062] The first embodiment shown in Fig. 1 has, for stiffening and / or suspending the filter element 4, a circular gas-permeable support disc 16 which is fastened to the support tube 3 and to the filter element 4, preferably by means of clamps, and arranged at a distance between the gas-impermeable support discs 6 and oriented orthogonally to the longitudinal direction of the support tube 3.

[0063] The filter device 1 can also have several gas-permeable support discs 16 for stiffening and / or suspending the filter element 4.

[0064] The embodiment of the filter device 1 shown in Fig. 1 has a bearing 21, preferably at least one ball bearing, and a seal 22, preferably a mechanical seal, between the support tube 3 and the filter housing 2.

[0065] Furthermore, a rotary feedthrough 19 for discharging the clean gas from the gas outlet opening 8 into a clean gas outlet opening 20 is also shown, which also has a seal 22, preferably a mechanical seal, towards the support tube 3.

[0066] In the filtering state of the filter device 1, the gas mixture to be filtered advantageously flows from the raw gas supply opening 17 into the dust collection housing 10, through the gas supply opening 9 or raw gas overflow opening 12 into the filter housing 2, through the filter element 4, through the gas inlet openings 7 into the support tube 3, out of the support tube 3 through the gas outlet opening 8, into the rotary feedthrough 19 and through the clean gas outlet opening 20, whereby it leaves the filter device 1.

[0067] In the cleaning state of the filter device 1, the filter element 4 or the filter drum 23 rotates so that centrifugal forces act on the dust particles deposited on the filter element 4, whereby the dust particles collected there are released from the filter element 4 and fall to the ground in the direction of the dust collection housing 10.

[0068] Due to the rotation of the filter element 4, preferably at a high speed of up to approximately 3000 revolutions per minute, a pressure opposite to the flow direction 17 of the filtering state can arise within the filter drum 23 due to the rotating clean gas in the cleaning state, which can lead to a reversal of the flow direction of the gas mixture or clean gas through the filter element 4 and thus further assists the cleaning process.

[0069] In order to avoid repetition, the following descriptions of the embodiments shown in Figs. 2 and 5 primarily focus on the differences from the first embodiment. Otherwise, the above description of the first embodiment also applies, where applicable, to the embodiments described below.

[0070] The second embodiment of a filter device 1 according to the invention shown in Fig. 2, also as a vertical section, differs from the first embodiment shown in Fig. 1 in that the filter device 1 has two gas-permeable support disks 16 for stiffening and / or suspending the filter element 4.

[0071] Figures 3 and 4 show horizontal sections through a filter device 1 according to the invention, wherein Figure 3 shows a plan view of a gas-impermeable support disc 6 and Figure 4 shows a plan view of a gas-permeable support disc 16.

[0072] The horizontal sections of Figs. 3 and 4 relate to the first two embodiments shown in Figs. 1 and 2, in each of which exactly one filter element 4 is arranged within a cylindrical filter housing 2.

[0073] In general, however, several filter elements 4 or filter drums 23 can also be arranged within a filter housing 2.

[0074] Fig. 5 shows an embodiment of a filter device 1 according to the invention, in which three filter elements 4 or filter drums 23 are arranged within a filter housing 2.

[0075] In this example, each filter element 4 or each filter drum 23 can be rotated by means of a drive 5.

[0076] However, it is also conceivable that the filter elements 4 or filter drums 23 can be rotated by means of a shared drive 5.

[0077] The filter housing 2 can have a cylindrical, rectangular or other shape.

[0078] In the embodiment of Fig. 5, a dust collection housing 10 is located below the filter housing 2, in which the dust separated by all three filter elements 4 is collected.

[0079] In this embodiment, the

[0080] Dust collection housing 10 has a transport screw 15 for transporting the separated dust in the direction of the dust lock 13.

[0081] When using a conveyor screw 15 as a dust transport means within the dust collection housing 10, it is advantageous that the dust collection housing 10 is channel-shaped, i.e. essentially form-fitting with the outer contour of the conveyor screw 15, so that the dust can be transported efficiently.

[0082] Other dust transport means, such as conveyor belts, scrapers or the like, can also be used, wherein a shape of the dust collection housing 10 adapted to the dust transport means is advantageous.

[0083] Even in a design with several filter elements 4 or filter drums 23 within a filter housing 2, the advantage is achieved that the centrifugal forces generated by the rotation of several filter elements 4 can reverse the flow direction, which can improve the cleaning of the filter elements 4.

[0084] The reversal of the flow direction is to be understood as meaning that the gas mixture flowing from the outside to the inside through the respective filter element 4 in the filtered state changes its flow direction so that the clean gas flows from the inside to the outside through the respective filter element 4. Key to the reference numbers:

[0085] filter device

[0086] filter housing

[0087] Support tube

[0088] filter element

[0089] Drive gas-tight support discs

[0090] Gas inlet openings

[0091] Gas outlet opening

[0092] Gas supply opening

[0093] Dust collection housing

[0094] Raw gas supply opening

[0095] Raw gas overflow opening

[0096] Dust lock

[0097] Conveyor screw drive

[0098] Conveyor screw gas-permeable support disc

[0099] Direction of movement of the gas mixture

[0100] Direction of movement of larger dust particles

[0101] rotary union

[0102] Re Ingas from the opening

[0103] storage

[0104] seal

[0105] Filter drum

Claims

Patent claims Filter device (1) for separating dust particles from a gas mixture, comprising a filter housing (2), at least one support tube (3) rotatably mounted in the filter housing (2), at least one cylindrical filter element (4) rotatable with the support tube (3), and at least one drive (5) for rotating the support tube (3) and the filter element (4), characterized in that the filter element (4) can be cleaned exclusively by means of the centrifugal forces generated by rotation of the filter element (4) with the support tube (3). Filter device (1) according to claim 1, characterized in that the filter element (4) can be rotated by the drive (5) at a minimum tangential speed on an outer surface of the filter element (4) of 20 m / s for cleaning the filter element (4).Filter device (1) according to claim 1 or 2, characterized in that the filter device (1) has two on the support tube (3) aligned orthogonally to the longitudinal direction of the support tube (3) and spaced from each other on. The filter element (4) is fastened to the support tube (3) and rotatable with the support tube (3) by the drive (5), to which support discs (6) the filter element (4) is fastened, preferably by means of clamps. Filter device (1) according to claim 3, characterized in that the support tube (3) has a plurality of gas inlet openings (7) on the outer surface in the region between the gas-impermeable support discs (6) and at least one gas outlet opening (8) at one end of the support tube for discharging clean gas purified by the filter element (4). Filter device (1) according to one of claims 1 to 4, characterized in that the filter housing (2) has at least one gas supply opening (9) which is designed to supply the gas mixture to be filtered into the filter housing (2).Filter device (1) according to claim 5, characterized in that at least one, preferably channel-shaped, dust collection housing (10) is arranged below the filter housing (2), which has at least one raw gas supply opening (11) for supplying the gas mixture to be filtered into the dust collection housing (10), and at least one raw gas overflow opening (12) which is congruent with the gas supply opening (9) of the filter housing (2) for supplying the gas mixture to be filtered from the dust collection housing (10) into the filter housing (2), wherein the raw gas overflow opening (12) simultaneously has a dust removal opening for removing the dust from the filter element. (4) separated dust from the filter housing (2) into the dust collection housing (10). Filter device (1) according to claim 6, characterized in that the raw gas overflow opening (12) is arranged at a distance from the raw gas supply opening (11). Filter device (1) according to claim 6 or 7, characterized in that the dust collection housing (10) has at least one dust lock (13) for discharging the separated dust from the dust collection housing (10), and / or at least one transport screw (15) rotatable by means of a transport screw drive (14) for transporting the separated dust within the dust collection housing (10).Filter device (1) according to one of claims 3 to 8, characterized in that the filter device (1) has at least one circular, gas-permeable support disc (16) for stiffening and / or suspending the filter element (4), which is fastened to the support tube (3) and to the filter element (4), preferably by means of clamps, and arranged at a distance between the gas-impermeable support discs (6) and oriented orthogonally to the longitudinal direction of the support tube (3). Method for operating a filter device (1) according to one of claims 1 to 9, wherein the filter element (4) of the filter device (1) is connected to the support tube (3) for cleaning the dust from the filter element (4). is rotated exclusively by means of centrifugal forces, preferably with a minimum tangential speed on an outer surface of the filter element (4) of 20 m / s.

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