Oil mist separator

Abstract

The invention relates to a filter system (1) for separating liquid impurities that are present in droplet or mist form from a gaseous substance stream, the filter system comprising a housing (2) in which a filter insert (5) is arranged, wherein the housing (2) has an inlet (11) and an outlet (12) for the substance stream, wherein the filter insert (5) has multiple filter layers (7) arranged substantially parallel to one another, wherein the filter layers (7) are arranged in the housing (2) such that a substance stream entering through the inlet (11) enters the filter layers (7) at an end face, wherein the housing (1) (a) has a front portion (21) in which the inlet (11) is arranged; (b) has a rear portion (23) in which the outlet (12) is arranged, and (c) has a middle portion (22) which is situated between the front portion (21) and the rear portion (23) and in which the filter layers (7) of the filter insert (5) are arranged substantially vertically.

Description

[0001] OIL MIST FROM SEPARATOR

[0002] The invention relates to a filter system for separating liquid accompanying substances in droplet or mist form from a gaseous material stream, comprising a housing in which a filter insert is arranged, wherein the housing has an inlet and an outlet for the material stream.

[0003] Background of the invention

[0004] Oil mist separators treat gaseous streams to remove liquid fractions in the form of droplets or mist. Current technology uses various filter systems based on different physical principles. Centrifugal separators are often used, in which droplets with a higher mass than the gas stream itself are separated by centrifugal action.

[0005] Generic filter systems feature filter media in which the droplets are trapped and then collect in the housing as a liquid fraction. The advantage of filtering separators is the consistently high, defined separation efficiency, depending on the filter media used. However, the installation space required in such filter systems to keep pressure loss low is considerable. Therefore, the use of such filter systems is currently limited to non-mobile applications such as stationary gas engines or stationary diesel engines.

[0006] A first approach to improving such filter systems is described in US 9,272,236 B2, in which the filter system comprises several filter layers arranged in a housing such that the material flow enters the filter layers at the front and flows through the filter insert. This design not only demonstrates higher separation efficiency with less space required, but also a longer service life compared to filter systems in which the filter layers are stacked and the material flow hits the filter layers head-on and flows through the filter layers layer by layer. In US 9,272,236 B2, the filter layers are installed such that they lie horizontally in the housing. This arrangement has a positive effect on the material flow, which can flow optimally through the filter medium, thus reducing the pressure drop through the filter medium. It also promotes the downward drainage of the separated liquid.Although the filter system according to US 9,272,236 B2 offers a long service life with high filter performance and a low installation height compared to other filter systems, there is still a need for filter systems with an even longer service life. This is particularly important in applications where replacing the filter media is labor-intensive and / or where the downtime of the filter system leads to production downtime.

[0007] Brief description of the invention

[0008] The object of the present invention is therefore to improve a filter system of the type mentioned at the outset in such a way that the service life is improved. This object is achieved by a filter system for separating liquid accompanying substances in droplet or mist form from a gaseous material flow, comprising a housing in which a filter insert is arranged, wherein the housing has an inlet and an outlet for the material flow, wherein the filter insert has a plurality of filter layers which are arranged substantially parallel to one another, wherein the filter layers are arranged in the housing in such a way that a material flow entering through the inlet enters the filter layers at the front, characterized in that the housing

[0009] (a) has a front portion in which the inlet is arranged;

[0010] (b) has a rear portion in which the outlet is arranged and

[0011] (c) has a central section between the front and rear sections in which the filter layers are arranged substantially vertically.

[0012] It has been shown that the filter system according to the invention, with a vertical arrangement of the filter layers in the housing, enables improved separation efficiency with a longer service life. Above all, such a filter system has the advantage over US Pat. No. 9,272,236 B2 that the separation efficiency is greater over longer operating times.

[0013] To ensure that the material flow can enter the filter layers optimally, the front section can be provided with an empty space, whereby the empty space extends essentially over the entire height of the filter layers. The inlet is located in the front section in the area of ​​the empty space. The front empty space allows the material flow to be distributed homogeneously over the entire height of the filter layers and then enter the individual filter layers evenly. The rear section can also have an empty space, whereby the empty space extends essentially over the entire height of the filter layers. This leads to a lower pressure loss in the filter system. The outlet is located in the rear section in the area of ​​the empty space.

[0014] The inlet is connected to a source for the gaseous stream, which contains accompanying liquid substances in the form of droplets or mist. The inlet is located in the front section, in the area of ​​the empty space. The front empty space allows the stream to be distributed evenly across the entire height of the filter layers and then enter the individual filter layers evenly.

[0015] The rear section can also have a void, with the void extending essentially the entire height of the filter layers. This results in a lower pressure drop in the filter system. The outlet is located in the rear section in the area of ​​the void.

[0016] Preferably, the inlet is arranged in the housing at a first height and the outlet is arranged in the housing at a second height, wherein the first height is below the second height.

[0017] The height of the housing is preferably at least twice the width of the housing.

[0018] In one embodiment, at least one retaining element for the filter layers is provided between the front section and the middle section, and / or at least one retaining element for the filter layers is provided between the rear section and the middle section. This embodiment ensures that the filter layers remain in the middle section and are not pushed into the front or rear section. The retaining elements are arranged to prevent the filter layers from slipping sideways.

[0019] In one embodiment, for example, the respective retaining element may be selected from the group consisting of a strut, mesh plate, perforated plate, or combinations thereof. The simplest and most cost-effective variant is at least one strut (e.g., as a transverse strut or longitudinal strut), which also has the advantage of minimizing the pressure loss caused by the surface area of ​​the retaining elements. A mesh plate or perforated plate is also suitable for holding the filter layers in the central section while still allowing the material flow to enter the filter layers.

[0020] Preferably, the filter insert forms at least one stack of individual filter layers, preferably packed essentially without any gaps, with the flow direction of the material stream being essentially parallel to the interfaces of the filter layers. This maximizes the separation efficiency because the material stream can penetrate the filter layers more effectively. Typically, at least five essentially parallel, adjacent filter layers are provided. In a preferred embodiment, the filter insert comprises two stacks of filter layers.

[0021] When using two stacks of filter layers, one stack acts as a pre-filter and one stack as a fine filter. The pre-filter primarily serves to catch splash oil, i.e. liquid droplets of oil, whereas the fine filter actually filters out oil in mist form. The materials used for the two stacks can be different, but they don't have to be. A glass fiber fabric, which has a lower filtering effect than the fine filter, has proven advantageous as a pre-filter. This results in lower pressure loss. There should be a spatial separation or interruption between the two stacks. This prevents the oil that has already penetrated the pre-filter stack from completely penetrating and subsequently being forced into the filing filter.

[0022] The filter layers are preferably made of mineral fibers and are several centimeters thick. The mineral fibers have a long-filament structure.

[0023] Furthermore, the adjacent filter layers can be arranged offset. The offset arrangement of the filter layers can increase the inlet and outlet areas for the material flow. This can also reduce the inlet pressure resistance and promote the outflow of the aggregated liquid at the outlet area. The filter layers can be arranged offset from one another by a certain distance on the inlet and outlet sides for the material flow. The distances can also be different on the inlet and outlet sides, or an offset can be provided only at the inlet or only at the outlet. The filter layers can also be arranged alternately offset to create a toothed profile. The filter layers can also be at least partially offset. The offset is preferably between 50 and 150% of the thickness of the respective filter layer.

[0024] Particularly preferably, the filter layers are compressible, with the filter layers being inserted into the housing with prestress. Prestressing describes a permanently acting compression force that is applied along the thickness of the filter layers and serves, among other things, to arrange the filter fibers partially parallel to the direction of the gas flow. It is also necessary that a prestress on the filter layers is permanently maintained after the filter layers have been inserted into the housing.

[0025] Compressible filter layers are those which, when relaxed, have a first volume, whereby the filter layers can assume a second volume through compression, which is smaller than the first volume. In this context, "pre-stressed" means that the filter layers are compressed in the housing, with an external force acting on the filter layers. The external force reduces the volume to a second volume, and the respective filter layer exhibits internal stress. When the external force is removed, the internal stress causes the filter layer to expand again. Such pre-stressed filter layers have a high separation efficiency and ensure a small installation space.

[0026] In one embodiment, the housing comprises an upper cover and a lower cover, with the upper cover covering the filter layers on the upper side and the lower cover covering the filter layers on the lower side. The filter layers are glued to the upper cover and the lower cover. This reduces the flow of the material past the edge of the housing.

[0027] The filter system preferably has an oil outlet in the rear section, wherein the oil outlet is connected to an oil reservoir, with the highest point of the oil reservoir being below the oil outlet. The height difference must be selected accordingly to prevent oil from being sucked back into the oil outlet. This ensures that oil separated in the filter medium is separated and drained from the filter system. To prevent a backflow of oil or the suction of gas from the oil reservoir, a siphon can be arranged between the oil outlet and the oil reservoir. This siphon can be constructed as a pipe-in-pipe siphon or in the classic form of a horizontal S-shaped pipe or hose run. The distance or the height difference of the siphon to the filter base must be selected such that it cannot be sucked dry by the prevailing suction pressure in the filter system.A siphon is only relevant if there is a non-continuous drainage hose return below the oil level in the oil reservoir.

[0028] Such filter systems are suitable, for example, for internal combustion engines, especially gas engines or diesel engines, but also for other areas where liquid, droplet, or mist-like accompanying substances need to be filtered from a gaseous stream. Examples include ventilation systems in kitchens. Therefore, the invention also relates to:

[0029] • an internal combustion engine, preferably a gas engine or diesel engine, comprising a filter system of the aforementioned type;

[0030] • a ventilation system for a kitchen, comprising a filter system of the aforementioned type; or

[0031] • a pump comprising a filter system of the aforementioned type.

[0032] Detailed description of the invention

[0033] Fig. 1 shows a filter system according to the state of the art

[0034] Fig. 2 shows an embodiment of the filter system according to the invention in oblique view (Fig.

[0035] 2a) and in side view (Fig. 2b)

[0036] Fig. 3 shows an oblique view of the filter system according to the invention from Fig. 2 in the open state

[0037] Fig. 4 shows a holding element for the filter layers for the filter system of Fig. 2 and 3

[0038] Fig. 5 shows the lower cover of the filter system of Fig. 2 and 3

[0039] Fig. 6 shows a filter system in the open state including the filter insert for the invention in section (Fig. 6a) and in oblique view (Fig. 6b).

[0040] Fig. 7 shows a filter system with a siphon. Fig. 1 shows a filter system 1 according to the prior art according to US Pat. No. 9,272,236 B2. The prior art filter system 1 comprises a housing 2 in which a filter insert 5 is arranged. The housing 2 has an inlet 11 and an outlet 12 for the material flow, the filter insert 5 having a plurality of filter layers 7 arranged essentially parallel to one another. The filter layers 7 are arranged horizontally in the housing 2. A material flow entering through the inlet 11 can enter the filter layers 7 at the end.

[0041] 2a and 2b show two views of a filter system 1 according to the invention for separating liquid accompanying substances in droplet or mist form from a gaseous material stream. The filter system 1 comprises a housing 2 in which a filter insert 5 (see Figs. 6a and 6b) is arranged. The housing 2 also has an inlet 11 and an outlet 12 for the material stream. The flow direction of the material stream is indicated by arrows. The inlet 11 is arranged in the housing 2 at a first height, and the outlet 12 is arranged in the housing 2 at a second height, wherein the first height is below the second height. In simple terms, the inlet 11 is therefore arranged below the outlet 12.

[0042] The height of housing 2 is more than twice as large as its width—in the illustrated example, approximately three times as large. This design further increases the separation efficiency.

[0043] The housing 2 comprises an upper cover 14 and a lower cover 15, wherein the upper cover 14 and the lower cover 15 cover the filter layers 7 when closed. The filter layers 7 are glued to the upper cover 14 and the lower cover 15 (not shown). For this purpose, it is advantageous if the inner surface of the respective cover is roughened (see Fig. 5, which shows the inside, i.e., the inner surface of the lower cover 15).

[0044] In the rear section 23 of the housing 2, an oil outlet 19 is arranged through which collected liquid can be discharged.

[0045] Fig. 6 shows a variant of the filter insert 5 in the housing 2 in section (Fig. 6a) and in oblique view (Fig. 6b), whereby the filter insert 5 in this variant has two stacks with several filter layers 7. The filter layers 7 are arranged essentially parallel to one another in each stack. The housing 2 forms the housing for the filter insert 5. As indicated by the four transverse arrows in Fig. 6a, a prestress acts on the filter layers 7 on both sides along their thickness. The filter layers 7 are compressible, so that the filter layers 7 are compressed in the housing 2 due to the prestress, since the prestress applies a permanently acting compression force along the thickness of the filter layers 7. As a result, the filter fibers are arranged partially parallel to the direction of the gas flow. The housing 2, which forms a housing for the filter insert 5, thus permanently prestresses the filter layers 7.Such pre-stressed filter layers 7 have a high separation efficiency and ensure a small installation space.

[0046] The filter layers 7 are arranged in the housing 2 such that a material flow entering through the inlet 11 enters the filter layers 7 at the end face. The filter insert 5 is designed as at least one stack of individual filter layers 7, preferably packed essentially without any gaps, wherein the filter insert 5 is arranged such that the flow direction of the material flow is essentially parallel to the interfaces 8 of the filter layers 7. With two stacks of filter layers 7 - as shown in Figs. 6a and 6b - the material flow first enters the first stack and then the second stack. In the exemplary embodiment shown, several essentially parallel, adjacent filter layers 7 are provided in two stacks, wherein the adjacent filter layers 7 are arranged offset in each of the stacks. The offset arrangement of the filter layers 7 allows the inlet and outlet areas for the material flow to be increased.This also reduces the inlet pressure resistance and promotes the outflow of the aggregated liquid at the outlet surface. In the embodiment shown in Figs. 6a and 6b, the filter layers 7 are arranged alternately offset in each stack, resulting in a toothed profile for each stack. The filter layers 7 can also be arranged at least partially offset. The offset is preferably between 50 and 150% of the thickness of the respective filter layer 7.

[0047] Fig. 3 shows the opened housing 2, which has a front section 21 in which the inlet 11 is arranged. In addition, a rear section 23 is provided, in which the outlet 12 is arranged. The middle section 22 is between the front section 21 and the rear section 23, in which the filter layers 7 of the filter insert 5 are arranged essentially vertically. The front section 21 has an empty space, wherein the empty space extends essentially over the entire height H of the filter layers 7. Between the front section 21 and the middle section 22, a holding element 25 for the filter layers 7 is shown in simplified form in Fig. 3, which prevents any lateral displacement of the filter layers 7.

[0048] A holding element 26 for the filter layers 7 is also provided between the rear section 23 and the middle section 22. The holding elements 25, 26 can be designed, for example, as a perforated sheet, as shown in Fig. 4. In Fig. 3, the holding elements 25, 26 are shown in a simplified form as a surface. However, struts could also be provided instead of a perforated sheet.

[0049] As shown in Fig. 7, the oil outlet 19, which can be connected to an oil reservoir, with the highest point of the oil reservoir located below the oil outlet 19, can be followed by a siphon 20. The siphon 20 is arranged between the oil outlet 19 and the oil reservoir to prevent backflow from the oil reservoir or a bypass of unfiltered gas flow into the housing 2. All components of the oil drainage system, and thus also the oil reservoir, are preferably sealed against the environment. This prevents the intake of external air.

Claims

Claims 1. Filter system (1) for separating liquid accompanying substances in droplet or mist form from a gaseous material flow, comprising a housing (2) in which a filter insert (5) is arranged, wherein the housing (2) has an inlet (11) and an outlet (12) for the material flow, wherein the filter insert (5) has a plurality of filter layers (7) which are arranged substantially parallel to one another, wherein the filter layers (7) are arranged in the housing (2) in such a way that a material flow entering through the inlet (11) enters the front side of the filter layers (7), characterized in that the housing (1) (a) has a front portion (21) in which the inlet (11) is arranged; (b) has a rear portion (23) in which the outlet (12) is arranged and (c) has a central section (22) between the front section (21) and the rear section (23), in which the filter layers (7) of the filter insert (5) are arranged substantially vertically.

2. Filter system according to claim 1, characterized in that the front section (21) has an empty space, wherein the empty space extends substantially over the entire height (H) of the filter layers (7).

3. Filter system according to claim 1 or claim 2, characterized in that holding elements (25) for the filter layers (7) are provided between the front section (21) and the middle section (22) and / or that holding elements (26) for the filter layers (7) are provided between the rear section (23) and the middle section (22).

4. Filter system according to claim 3, characterized in that the holding elements (25, 26) are selected from the group consisting of cross strut, grid plate, perforated plate or combinations thereof.

5. Filter system according to one of claims 1 to 4, characterized in that the filter insert (5) forms at least one stack of individual filter layers (7) which are preferably packed essentially without any gaps, wherein the filter insert (5) is arranged such that the flow direction of the material flow is essentially parallel to the boundary surfaces (8) of the filter layers (7). RECTIFIED SHEET (RULE 91) ISA / EP 6. Filter system according to one of claims 1 to 5, characterized by at least five substantially parallel, adjacent filter layers (7).

7. Filter system according to one of claims 1 to 6, characterized in that the filter layers (7) comprise compressible material, wherein the filter layers (7) are introduced into the housing (2) with prestress.

8. Filter system according to one of claims 1 to 7, characterized in that the housing (2) has an upper cover (14) and a lower cover (15), wherein the upper cover (14) and the lower cover (15) cover the filter layers, wherein the filter layers are glued to the upper cover (14) and to the lower cover (15).

9. Filter system according to one of claims 1 to 8, characterized in that an oil outlet (19) is arranged in the rear section (23), wherein the oil outlet (19) is connected to an oil reservoir, wherein the highest point of the oil reservoir is below the oil outlet (19).

10. Filter system according to claim 9, characterized in that a siphon is arranged between the oil outlet (19) and the oil reservoir.

11. Combustion engine, preferably gas engine or diesel engine, or ventilation systems for a kitchen or pump, comprising a filter system according to one of claims 1 to 10. RECTIFIED SHEET (RULE 91) ISA / EP

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