Biofilter for Biological Purification of a Waste Gas Stream Containing Impurities

Abstract

The invention relates to a biofilter for biologically cleaning a waste gas stream containing contaminants, having at least one filter module through which the waste gas stream is to flow. The filter module has at least one filter layer containing an organic filter material, and the at least one filter layer being supported by at least one grating structure which is in particular oriented at least substantially horizontally. According to the invention, so that the biofilter can be operated cost-effectively, with low effort and with a high filtering efficiency over the longest possible period, the at least one grating structure formed by elongate grating elements which are arranged at least substantially crosswise and are in particular oriented at least substantially horizontally.

Claims

1-18. (canceled)

19. A biofilter for biological purification of an exhaust gas stream containing impurities, having at least one filter module through which the exhaust gas stream is to flow, the filter module having at least one filter layer comprising an organic filter material, and the at least one filter layer being supported by at least one, in particular at least substantially horizontally oriented, grid structure, wherein the at least one grid structure is formed by at least substantially rectangular crosswise and arranged on top of each other elongated, at least substantially horizontally aligned, grid elements in the form of wooden slats.

20. The biofilter according to claim 19, wherein the grid elements of the at least one grid structure are each lath-shaped, beam-shaped and/or rod-shaped and/or in that the grid elements of the at least one grid structure are at least substantially unconnected to one another and/or are connected to one another releasably, in particular positively and/or non-positively, and/or in that the grid elements of the at least one grid structure are formed from wood and/or a wood material.

21. The biofilter according to claim 19, wherein the at least one grid structure is formed from at least two, preferably at least three, in particular at least four, in particular arranged on top of each other and/or horizontally aligned grid layers, and in that, preferably, the grid layers are each formed by crosswise arranged elongated grid elements.

22. The biofilter according to claim 19, wherein the grid elements of the at least one grid structure and/or of the grid layers cross one another at least substantially at right angles, and/or in that grid openings of a width and/or length of at least 10 cm, preferably at least 15 cm, in particular at least 20 cm, and/or at most 120 cm, preferably at most 80 cm, in particular at most 60 cm, are provided within the at least one grid structure and/or the grid layers, as seen in the vertical direction (RV).

23. The biofilter according to claim 19, wherein the grid elements occupy at least 20% by volume, preferably at least 30% by volume-%, in particular at least 35% by volume, and/or at most 70% by volume, preferably at most 60% by volume, in particular at most 55% by volume, of the volume of the at least one grid structure.

24. The biofilter according to claim 19, wherein the grid elements of the at least one grid structure each have a length of at least 80 cm, preferably at least 120 cm, in particular at least 160 cm, and/or at most 10 m, preferably at most 8 m, in particular at most 6 m, and/or a thickness (DGE) of at least 1 cm, preferably at least 2 cm, in particular at least 3 cm, and/or at most 15 cm, preferably at most 10 cm, in particular at most 5 cm, and/or a width (BGE) of at least 5 cm, preferably at least 10 cm, in particular at least 15 cm, and/or at most 80 cm, preferably at most 60 cm, in particular at most 40 cm.

25. The biofilter according to claim 19, wherein the at least one filter layer is designed as a bulk layer and/or that the filter material of the at least one filter layer comprises wood chips, in particular coniferous wood chips, bark mulch, fibrous peat, coconut fibers, torn root wood, biowaste compost, heather, wood wool and/or wood pellets.

26. Biofilter according to claim 19, wherein between the at least one filter layer and the at least one grid structure, a supporting layer having a plurality of passage openings is provided for supporting the filter layer above the grid structure, and in that, preferably, the supporting layer is formed at least substantially from metal or plastic, in particular polyethylene or polypropylene, and/or by at least one grid, perforated grid, mesh and/or fabric.

27. The biofilter according to claim 19, wherein the at least one grid structure has a layer thickness (DGS) of at least 20 cm, preferably at least 30 cm, in particular at least 40 cm, and/or at most 100 cm, preferably at most 80 cm, in particular at most 60 cm, and/or in that the at least one filter layer has a layer thickness (DFS) of at least 30 cm, preferably at least 40 cm, in particular at least 50 cm, and/or at most 150 cm, preferably at most 125 cm, in particular at most 100 cm, and/or in that the at least one support layer has a layer thickness (DSS) of at most 5 cm, preferably at most 3 cm, in particular at most 1 CM.

28. The biofilter according to claim 19, wherein an inflow chamber for the exhaust gas flow is provided below the at least one grid structure, and in that, preferably, the at least one inflow chamber has a height (HA) of at least 20 cm, preferably at least 30 cm, in particular at least 40 cm, and/or at most 120 cm, preferably at most 100 cm, in particular at most 80 cm.

29. The biofilter according to claim 19, wherein the at least one filter module has at least two, preferably at least three, filter layers each supported by a grid structure, and in that, preferably, a support layer is provided between the filter layers and the grid structures in each case and/or an inflow chamber is provided under each grid structure.

30. The biofilter according to claim 19, wherein a supporting framework is provided for supporting the at least one grid structure, in particular at least in sections in the at least one inflow chamber, and in that, preferably, the supporting framework supports at least substantially the entire weight force of the at least one grid structure and the at least one filter layer on the bottom of the filter module and/or the supporting framework supports at least one lower grid structure and one upper grid structure and extends through the filter layer supported by the lower grid structure and at least substantially through the inflow chamber arranged below the upper grid structure.

31. The biofilter according to claim 30, wherein the supporting framework is formed at least substantially from a steel material, in particular a galvanized steel material, a stainless steel material and/or a plastic-coated steel material, a plastic, in particular polyethylene and/or polypropylene, from wood or a wood material, preferably from coniferous wood, and/or in that the supporting frame is designed as a tubular frame.

32. The biofilter according to claim 19, wherein at least one moistening device for moistening the filter layer is associated with the at least one filter layer, and in that, preferably, the at least one moistening device has at least one nozzle for applying a water-containing moistening fluid to the filter layer.

33. The biofilter of claim 32, wherein the filter module has at least one lower filter layer and at least one upper filter layer, and in that at least one supply line of the moistening device assigned to the lower filter layer extends at least partially, in particular at least essentially in the vertical direction (RV), through the upper filter layer, and in that, preferably, the at least one nozzle assigned to the lower filter layer is held on the at least one supply line, in particular suspended, and/or in the inflow chamber of the upper filter layer.

34. The biofilter of claim 33, wherein the at least one supply line is arranged in sections in at least one line duct extending at least substantially through the upper filter layer, in particular formed by a pipe and/or a hose, and in that, preferably, the at least one nozzle associated with the lower filter layer is passed through the at least one line shaft.

35. The biofilter according to claim 33, wherein a control device is provided for controlling the at least one moistening device, in particular as a function of at least one measured moisture value measured by at least one moisture sensor, and in that, preferably, the at least one moisture sensor is designed for measuring the filter material moisture of the at least one filter layer.

36. The biofilter according to claim 19, wherein the at least one filter module is open at the top, in particular at least substantially over the entire horizontal extent of the at least one filter layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention is explained in more detail below by means of a drawing which merely illustrates an example of an embodiment. The drawing shows

[0051] FIG. 1 a schematic vertical sectional view of a biofilter according to the invention,

[0052] FIG. 2 a detail of the biofilter from FIG. 1 in a schematic vertical sectional view and

[0053] FIG. 3 detail of the biofilter of FIG. 1 in a schematic horizontal sectional view from above.

DESCRIPTION OF THE INVENTION

[0054] In FIG. 1, a biofilter 1 is shown in a schematic vertical sectional view. The biofilter 1 is used for biological purification of an exhaust gas stream containing biodegradable contaminants, such as odors and/or pollutants. In the illustrated and in this respect preferred embodiment example, the biofilter 1 has a filter module 2. The contaminated exhaust gas stream is fed to the filter module 2 via an inflow opening 3, which then flows upwards through the filter module 2 at least substantially in the vertical direction RV and is finally discharged as a cleaned exhaust gas stream from the filter module 2, which is open at the top, into the environment 4. Alternatively, the filter module 2 could also be designed such that the exhaust gas stream flows through the filter module 2 from top to bottom. However, this is not preferred.

[0055] The filter module 2 has a lower filter layer 5 and an upper filter layer 6 through which the exhaust gas stream flows in succession. The filter layers 5,6 are designed as bulk layers. As filter material, the filter layers 5,6 presently have wood chips of a coniferous wood. The filter layers 5,6 are each supported by a grid structure 7,8 extending at least substantially in the horizontal direction RH. The grid structures 7,8 are each formed by elongated grid elements 9,10 arranged crosswise, which in the present case rest loosely on one another. In the illustrated and thus preferred embodiment, the lowermost grid elements 9 of the two grid structures 7,8 are designed as wooden beams and the remaining grid elements 10 arranged above them as wooden slats. Between the lower grid structure 7 and the lower filter layer 5, and between the upper grid structure 8 and the upper filter layer 6, a supporting layer 11 in the form of a plastic mesh is arranged in each case. Via the support layers 11, the filter layers 5,6 are each supported on the grid structure 7,8 carrying the respective filter layer 5,6. In alternative biofilters, three or four filter layers, each supported by a grid structure, can also be provided one above the other in this way.

[0056] The grid structures 7,8 are supported by a supporting frame 12. The supporting framework 12 is designed as a tubular frame consisting essentially of horizontal and vertical support tubes 13,14, which are made of a galvanized steel material. The lowest grid elements 9 of the two grid structures 7,8 rest loosely on the horizontal support tubes 13 of the supporting framework 12. The horizontal support tubes 13 are in turn supported on the vertical support tubes 14 of the supporting framework 12. In this case, the vertical support tubes 14 supporting the upper grid structure 8 extend through the lower filter layer 5 and the lower grid structure 7. In this way, the supporting framework 12 supports substantially the entire weight force of both grid structures 7,8 and both filter layers 5,6 on the bottom 15 of the filter module 2.

[0057] An inflow chamber 16,17 is arranged below each of the grid structures 7,8. The lower inflow chamber 16 is essentially bounded in the vertical downward direction RV by the bottom 15 of the filter module 2 and in the vertical upward direction RV by the lower grid structure 7. The upper inflow chamber 17 is bounded at the bottom by the lower filter layer 5 and at the top by the upper grid structure 8. To the sides, both inflow chambers 16,17 are essentially bounded by the side walls 18 of the filter module 2. The lower inflow chamber 16 has a height HA of 70 cm and the upper inflow chamber 17 has a height HA of 50 cm.

[0058] For moistening the filter material of the filter layers 5,6, the biofilter 1 has a lower and an upper moistening device 19,20, the lower moistening device 19 being assigned to the lower filter layer 5 and the upper moistening device 20 being assigned to the upper filter layer 6. In this connection, the moistening devices 19,20 each have a plurality of nozzles 21 with which a moistening fluid can be applied to the filter layers 5,6. The nozzles 21 of the upper moistening device 20 are held by holding elements 22, each of which is inserted into the upper filter layer 6. The nozzles 21 of the lower moistening device 19, on the other hand, are held suspended from supply lines 23 of the lower moistening device 19, which in the present case are designed as flexible hoses. The supply lines 23 of the lower moistening device 19 extend in the vertical direction RV through the upper grid structure 8 and the upper filter layer 6. In the vicinity of the surface of the upper filter layer 6, the supply lines 23 of the lower moistening device 19 are connected to the supply lines 24 of the nozzles 21 of the upper moistening device 20, which in the illustrated embodiment example, however, by no means necessarily run just below the surface of the upper filter layer 6.

[0059] The sections of the supply lines 23 of the lower moistening device 19, which extend through the upper filter layer 6 and the upper grid structure 8, are arranged in line duct 25, which in the present case also extend through both the upper filter layer 6 and the upper grid structure 8. In this connection, the line duct 25 are formed in a simple manner as at least substantially rigid tubes which are attached in a manner not shown to at least one of the grid elements 9,10 of the upper grid structure 8. For representational reasons, the nozzles 21 of the lower moistening device 19 are shown in FIG. 1 to be larger than the diameters of the tubes forming the line duct 25. In fact, however, the nozzles 21 of the lower moistening devices 19 are made smaller than the cross-sections of the line duct 25, so that the nozzles 21 can be inserted into the upper inflow chamber 17 from above through the line duct 25 in a simple manner and can also be withdrawn again.

[0060] The nozzles 21 of the moistening devices 19,20 are controlled by a control device 26 of the biofilter 1. Thereby, the control device 26 is connected to several moisture sensors 27, which are arranged in the filter layers 5,6. The moisture sensors 27 measure the moisture of the filter material in the filter layers 5,6. Thus, the control device 26 can control the nozzles 21 depending on the measured moisture values measured by the moisture sensors 27. In this way, the moistening of the filter material by the moistening devices 19,20 can be adapted not only to changing process parameters, but also to intermittent rainfall that hits the filter module 2, which is open at the top, and thus contributes to the humidification of the filter material. In this context, a drain 28 arranged at the bottom 15 of the filter module 2 ensures that no excess water accumulates in the area of the bottom 15, which can occur in the event of over-wetting of the filter material, for example due to heavy rainfall.

[0061] In FIG. 2, a detail of the biofilter 1 according to the section II shown in FIG. 1 is shown in a schematic vertical sectional view. The grid elements 9,10 of the lower grid structure 7 lie crosswise on top of each other and are otherwise unconnected to each other. The lowest grid elements 9 are formed as beams, while the remaining grid elements 10 are formed as battens, boards or planks. The lowermost grid elements 9 would therefore not have to be regarded as part of the grid structures 7,8, but could also be understood as part of the supporting framework 12. In any case, in the illustrated embodiment example of a biofilter 1, several, more precisely three, grid layers 29 consisting of grid elements 9,10 provided crosswise are provided. Both the grid layers and the grid structures and the grid elements extend at least substantially in a horizontal direction.

[0062] In the biofilter 1 shown, which is preferred in this respect, the lower filter layer 5 has a layer thickness DFS of approx. 70 cm and the lower grid structure 7 has a layer thickness DGS of approx. 80 cm. The support layer 11 arranged between the lower grid structure 7 and the lower filter layer 5 has a layer thickness DSS of less than 1 cm. The lowest grid elements 9 of the lower grid structure 7, which are in the form of beams, have a thickness DGE of 8 cm and a width BGE of 15 cm. The remaining grid elements 10 of the lower grid structure 7, which are in the form of battens, have a thickness DGE of 3 cm and a width BGE of 18 cm.

[0063] In FIG. 3, a detail of the biofilter 1 is shown in a schematic horizontal sectional view along the sectional plane III-III shown in FIG. 1, wherein in sections the lower filter layer 5, the lower support layer 11 and/or grid elements 9,10 of the lower grid structure 7 are not shown. The meshes forming the support layers 11 arranged between the filter layers 5,6 and the grid structures 7,8 each have a plurality of passage openings 30. In this case, the passage openings 30 are designed in such a way that fine components of the filter material of the filter layers 5,6, for example decomposed by the microorganisms present in the filter module 2, can fall through the passage openings 30, but larger, unrotted components of the filter material cannot. Against this background, the nets forming the supporting layers 11 have a mesh size of approx. 3 cm in the illustrated and thus preferred embodiment example.

[0064] The grid elements 9,10 of the grid structures 7,8 are arranged in the illustrated and in this respect preferred embodiment example in such a way that they cross at least substantially at right angles. Thereby, a plurality of grid openings 31 are provided within the grid structures 7,8 as seen in vertical direction RV, which in the depicted and in this respect preferred biofilter 1 are each delimited by two intersecting pairs of parallel grid elements 9,10 and are arranged at least substantially congruent to each of the three grid layers 29 provided one above the other.

List of reference signs

[0065] 1 Biofilter [0066] 2 Filter module [0067] 3 Inlet opening [0068] 4 Surroundings [0069] 5,6 Filter layer [0070] 7,8 Grid structure [0071] 9,10 Grid element [0072] 11 Support layer [0073] 12 Supporting framework [0074] 13,14 Support tube [0075] 15 Floor [0076] 16,17 Inflow chamber [0077] 18 Sidewall [0078] 19,20 Moistening device [0079] 21 Nozzle [0080] 22 Holding element [0081] 23,24 supply line [0082] 25 Line duct [0083] 26 Control device [0084] 27 Moisture sensor [0085] 28 Drain [0086] 29 Grid layer [0087] 30 Opening [0088] 31 Grid opening [0089] BGE Width of the grid element [0090] DFS Thickness of the filter layer [0091] DGE Thickness of the grid element [0092] DGS Layer thickness of the grid structure DSSupport layer thickness [0093] HA Height of the inflow chamber [0094] RH Horizontal direction [0095] RV Vertical direction