Liquid substrate tank for a biogas plant

Abstract

A liquid substrate tank for a biogas plant includes an interior fillable with a liquid substrate and a bottom wall defining the interior on the bottom and being particularly at least regionally flat. A trough-shaped recess extending over a partial region of the bottom wall is formed in the bottom wall, to which and/or into which recess an extraction line of an extraction device is guided. The extraction device has an open-loop and/or closed-loop control device actuating the extraction device for extracting a substrate/sand mixture accumulating in the recess during operation from the recess and thus from the interior through the extraction line. The extraction device has an accommodation and/or sedimentation tank, or separator, connected to the extraction line relative to flow for accommodating or separating the substrate/sand mixture extracted through the extraction line into substrate and sand phases.

Claims

1. A liquid substrate tank for a biogas plant, the liquid substrate tank comprising: a tank base wall disposed at a tank base for delimiting an tank interior space to be filled with a liquid substrate; at least one trough-shaped depression formed in a predefined subregion of and extending over said tank base wall; a cylindrical inner tank contour; an extraction device having at least one extraction line being guided to or into said at least one trough-shaped depression; said extraction device having a control or regulation device configured to actuate said extraction device for extracting a substrate-sand mixture collecting in said at least one trough-shaped depression during operation from said at least one trough-shaped depression and from said tank interior space through said at least one extraction line; said extraction device having at least one receiving or sedimentation tank being connected to said at least one extraction line for receiving a flow of the substrate-sand mixture extracted through said at least one extraction line; said at least one trough-shaped depression forming at least one elongate extraction channel formed in said tank base wall, said at least one elongate extraction channel formed in said tank base wall lying in a flow path of the liquid substrate flowing over said tank base wall, and said at least one elongate extraction channel having a longitudinal side oriented and disposed perpendicular to a substrate flow direction in said tank interior space; and at least one flow-generating device or agitator being actuable for causing a liquid substrate accommodated in the liquid substrate tank to flow in at least one of a predefined substrate flow direction or at a predefined substrate flow speed at least one of above or along said tank base wall; said at least one flow-generating device or agitator being disposed in the liquid substrate tank and configured to impart a rotating flow or a rotating flow about a vertical tank axis to the liquid substrate upon said at least one flow-generating device or agitator being actuated.

2. The liquid substrate tank according to claim 1, wherein said tank base wall is at least regionally planar, and said at least one receiving or sedimentation tank is a separator for separating the substrate-sand mixture into a substrate phase and a sand phase.

3. The liquid substrate tank according to claim 2, which further comprises: a collecting line leading from said at least one extraction line to said receiving or sedimentation tank or separator; and a shut-off element being controlled by said control or regulating device for opening and closing said collecting line.

4. The liquid substrate tank according to claim 1, wherein said extraction device is a suction-extraction device, and said at least one extraction line is a suction-extraction line of said suction-extraction device.

5. The liquid substrate tank according to claim 4, wherein said suction-extraction device is a vacuum or negative-pressure suction-extraction device having at least one of: a vacuum or negative-pressure pump for extracting the pumpable substrate-sand mixture by suction from said at least one trough-shaped depression through said at least one suction-extraction line, or a vacuum or negative-pressure tank acting as separator, in which the substrate-sand mixture is received with a pressure lower than atmospheric pressure.

6. The liquid substrate tank according to claim 1, wherein said at least one extraction channel includes multiple extraction channels being spaced apart from one another in a substrate flow direction, being disposed in said tank interior space and lying in a flow path of the liquid substrate flowing over said tank base wall.

7. The liquid substrate tank according to claim 1, wherein said at least one extraction channel includes multiple elongate extraction channels being spaced apart from one another in a substrate flow direction and each having a longitudinal side disposed perpendicular to a substrate flow direction in said tank interior space.

8. The liquid substrate tank according to claim 1, wherein said at least one extraction channel is a single extraction channel or at least two extraction channels being spaced apart from one another and one behind the other in a longitudinal direction and extending as a diametrically running extraction channel between diametrically oppositely disposed base wall regions of the liquid substrate tank.

9. The liquid substrate tank according to claim 8, wherein the liquid substrate tank has a vertical tank central axis about which the liquid substrate rotates when said at least one flow-generating device or agitator is actuated, and said diametrically running extraction channel extends to two sides of said vertical tank axis.

10. The liquid substrate tank according to claim 9, wherein said at least one flow-generating device or agitator causes a substrate part of the liquid substrate rotating about said vertical tank axis to pass twice over said diametrically running extraction channel during one 360 revolution about said vertical tank axis.

11. The liquid substrate tank according to claim 1, wherein: the liquid substrate tank has a cylindrical inner contour and a vertical tank central axis about which the liquid substrate rotates when said at least one flow-generating device or agitator is actuated; and said at least one extraction channel includes multiple extraction channels being spaced apart from one another in a flow direction and extending outward in radial or stellate fashion from said vertical tank axis.

12. The liquid substrate tank according to claim 1, wherein said at least one extraction channel has a V-shaped or funnel-shaped cross section.

13. The liquid substrate tank according to claim 1, wherein said at least one extraction line is at least one horizontal extraction line running, relative to a tank vertical axis, in a horizontal plane at a level of said at least one extraction channel, and said at least one horizontal extraction line opens laterally or in an extraction channel side wall region into said at least one extraction channel.

14. The liquid substrate tank according to claim 1, wherein said at least one extraction line includes multiple extraction lines being spaced apart from one another in an extraction channel longitudinal direction and opening into said at least one extraction channel, and each of said extraction lines opens into an oppositely situated channel end region in an extraction channel longitudinal direction.

15. The liquid substrate tank according to claim 1, wherein said at least one extraction line includes multiple extraction lines being spaced apart from one another in an extraction channel longitudinal direction and opening into said at least one extraction channel, each of said extraction lines opens into an oppositely situated channel end region in an extraction channel longitudinal direction, and at least one extraction line opens into a channel intermediate region disposed between two channel end regions.

16. The liquid substrate tank according to claim 1, wherein: said at least one extraction line includes at least some extraction lines associated with different extraction channels; and a shut-off element is separately actuable by said regulating or control device for opening and shutting off at least said extraction lines associated with different extraction channels or for opening and shutting off each of said extraction lines.

17. The liquid substrate tank according to claim 1, which further comprises a tank wall, said at least one extraction line being formed by at least one extraction probe being inserted in a gas-tight manner through said tank wall into said tank interior space and being led in said tank interior space as far as into a vicinity of said at least one extraction channel.

18. The liquid substrate tank according to claim 1, which further comprises a tank roof and a tank side wall, said at least one extraction line being formed by at least one extraction probe and being inserted, relative to a tank vertical axis, in a gas-tight manner from above through said tank roof or from a side through said tank side wall, into said tank interior space and being led in said tank interior space as far as into a vicinity of said at least one extraction channel.

19. The liquid substrate tank according to claim 18, which further comprises a skirt disposed on said tank roof and dipping into the liquid substrate when the liquid substrate tank has been filled with the liquid substrate, said at least one extraction probe being adjustable in height and being led in a gas-tight and height-adjustable manner through said skirt into said tank interior space.

20. The liquid substrate tank according to claim 1, which further comprises: a shut-off element being separately actuable by said regulating or control device; said at least one extraction line being formed by at least one extraction probe being inserted into said tank interior space and being led in said tank interior space as far as into a vicinity of said at least one extraction channel; said at least one extraction probe including extraction probes associated with different extraction channels; and said extraction probes associated with different extraction channels or each of said extraction probes being opened and shut off by said shut-off element.

21. The liquid substrate tank according to claim 1, wherein said receiving or sedimentation tank is a separator, and at least one recirculation line is led from said separator to the liquid substrate tank.

Description

(1) In the drawing:

(2) FIG. 1a schematically shows a plan view of a liquid substrate tank of a biogas plant according to a first embodiment, with two extraction channels extending diametrically over a tank base wall,

(3) FIG. 1b shows the construction as per FIG. 1a with extraction lines leading to the extraction channels,

(4) FIG. 1c schematically shows a sectional view along the line A-A in FIG. 1b,

(5) FIG. 1d schematically shows a sectional view along the line B-B in FIG. 1a,

(6) FIG. 2a schematically shows a plan view of a second embodiment of a liquid substrate tank according to the invention, with a single diametrically running extraction channel,

(7) FIG. 2b schematically shows a sectional view along the line C-C in FIG. 2a,

(8) FIG. 2c schematically shows a sectional view along the line D-D in FIG. 2a,

(9) FIG. 2d schematically shows an illustration corresponding to FIG. 2a with an extraction channel illustrated in detail,

(10) FIG. 3a shows a schematic plan view of a third embodiment of a liquid substrate tank according to the invention, with an extraction probe opening into the substrate tank from above,

(11) FIG. 3b schematically shows a cross-sectional view of the construction as per FIG. 3a,

(12) FIG. 4a schematically shows a side view of a substrate tank according to a fourth embodiment,

(13) FIG. 4b schematically shows a sectional view along the line E-E in FIG. 4a,

(14) FIG. 4c schematically shows a sectional view along the line F-F in FIG. 4a,

(15) FIG. 4d schematically shows a sectional view along the line G-G in FIG. 4e,

(16) FIG. 4e schematically shows a plan view of the tank base wall illustrated in FIG. 4d with trough-like depressions at the edge, and

(17) FIG. 5 schematically shows an exemplary embodiment of a separator in the form of a receiving and/or sedimentation tank.

DESCRIPTION OF THE INVENTION

(18) FIG. 1a shows, schematically and by way of example, a plan view of a first embodiment of a liquid substrate tank 1 according to the invention for a biogas plant, which liquid substrate tank has a tank interior space 2 which can be filled with liquid substrate, a tank base wall 3 which delimits the tank interior space 2 at a base side and which in this case is of planar form, and, as can be seen in particular from FIG. 1c, a tank side wall 4 which circumferentially delimits the tank interior space 2. The tank interior space 2 is in this case covered by way of example, as per FIG. 1c, by a foil roof 5 such as is known per se.

(19) To generate a flow of the liquid substrate (not shown in detail here) which rotates about the vertical tank central axis 7 (corresponding to the arrows 8), multiple agitators 9a to 9e are provided so as to be circumferentially spaced apart from one another, which agitators are shown here merely by way of example and schematically. Whereas the agitators 9a, 9b and 9c are in this case merely by way of example and schematically arranged spaced apart from one another on the circular cylindrical tank side wall 4, the agitators 9d and 9e (see FIG. 1c) are held in height-adjustable and/or pivotable fashion on a vertical guide mast 10, wherein the guide mast 10 is mounted or held by way of its upper end in a service shaft 6, via which it is possible for installation and servicing equipment to access the agitators 9d and 9e, and via which the agitators 9d, 9e can be lifted out of the container interior space 2. The service shafts 6 themselves are supported and held, for example in conjunction with a pedestal plate 11, on the tank side wall 4, as can be seen in particular from FIG. 1a.

(20) As can also be seen when viewing FIGS. 1a to 1d together, it is the case here, by way of example, that two elongate and substantially rectilinearly running extraction channels are formed in the tank base wall 3, which extraction channels extend in each case outwardly proceeding from the tank central axis 7 to the tank side wall 4 and thus form a substantially diametrically running extraction channel between diametrically oppositely situated tank base wall regions or tank side wall regions of the liquid substrate tank 1.

(21) As can also be seen in particular from FIG. 1a, the extraction channels are in this case, with regard to their longitudinal side, oriented and arranged substantially perpendicular to the rotating substrate flow direction in the tank interior space 2, such that a substrate part, rotating about the vertical tank central axis 7, of the liquid substrate passes twice over the two extraction channels 12, which form one diametrically running extraction channel, during one 360 revolution about the vertical tank central axis 7, specifically, in relation to the extraction channels 12, at 0 and 180.

(22) As is illustrated merely schematically and by way of dashed lines in FIG. 1a, it would however also be possible for multiple extraction channels 12 to be provided and formed in the tank base wall 3, which extraction channels then altogether extend outward in radial or stellate fashion from the vertical tank central axis 7.

(23) As can be seen from FIG. 1d, which shows a section along the line B-B in FIG. 1a, the extraction channels have a preferred V-shaped or funnel-shaped cross section, such that the inner walls of the longitudinal sides 13 of the extraction channel 12 slope obliquely downward toward the base center. It is likewise possible, as can be seen in particular from FIG. 1a, for the oppositely situated transverse sides 14 to have obliquely inwardly downward-sloping inner walls.

(24) As can be seen in particular when viewing FIGS. 1b and 1c together, it is the case here that multiple extraction lines 15 spaced apart from one another in an extraction channel longitudinal direction open into each of the extraction channels 12, which extraction lines run in a horizontal plane relative to the tank vertical axis and, in this case, open in each case into the obliquely inwardly downward-sloping extraction channel side wall regions. As can be seen in particular from FIG. 1b, in each case one extraction line 15 opens into the oppositely situated channel end regions as viewed in the extraction channel longitudinal direction, whereas one extraction line 15 opens into the channel intermediate region 12a situated between said channel end regions.

(25) As can also be seen from FIG. 1b, it is the case here by way of example that each of the extraction lines 15 can be opened or shut off by way of a shut-off element 16 which is separately actuable by the regulating and/or control device 47, which shut-off element may for example be a slide or a valve, wherein it is furthermore provided here that all of the extraction lines 16 open into a collecting line 17, which collecting line in this case can likewise be closed and opened by way of a shut-off element 16 in a manner controlled by way of the control and/or regulating device, and which collecting line is led to a separator 18 shown in FIG. 5.

(26) With a liquid substrate tank 1 constructed in this way, the liquid substrate can have imparted to it the rotating flow (arrow 8) schematically shown in FIGS. 1a and 1b, whereby the individual substrate subregions pass over the individual extraction channels 12 multiple times during the course of several revolutions. The solids situated in the liquid substrate in this case sink down to the tank base wall 3 and can then, owing to the rotating flow and the extraction channels 12, be deposited as a substrate-sand mixture in the extraction channels 12, from where they can be extracted via the extraction lines 15 in a manner controlled by way of the control and/or regulating device, and supplied via the collecting line 17 to the separator 18. The shut-off elements 16 can in this case be individually actuated by way of the control and/or regulating device, and thus individual extraction, by suction, of the substrate-sand mixture from the extraction channels 12 can be realized.

(27) FIGS. 2a to 2d show an embodiment alternative to that in FIGS. 1a to 1d, wherein the liquid substrate tank 1 has for example a smaller diameter than that of the embodiment as per FIG. 1d. Furthermore, in this case, only a single extraction channel 12 extends diametrically between oppositely situated edge regions of the tank base wall 3 or between oppositely situated side wall regions of the tank side wall 4.

(28) In this case, too, extraction lines 15 which run horizontally into the extraction channel 12 in relation to the tank vertical axis direction open, spaced apart from one another, into the elongate extraction channel 12, specifically, in principle, analogously to the embodiment of FIGS. 1a to 1d, wherein, again merely by way of example, two further mutually spaced-apart extraction lines 15 open into the channel intermediate region between the two extraction lines 15 which open into the oppositely situated channel end regions.

(29) As a further difference in relation to the embodiment as per 1a to 1d, the tank interior space 2 in this case does not have a dome-like foil roof, but rather a planar roof-side cover 19, on which in this case, merely highly schematically and by way of example, two service shafts 6 with associated guide masts 10 and agitators 9d and 9e are arranged.

(30) Otherwise, the construction is identical to that of FIGS. 1a to 1d, such that, with regard to the operational extraction, by suction, of the substrate-sand mixture that accumulates in the extraction channel 12 in conjunction with a rotating flow of the liquid substrate, reference is made to the statements above.

(31) FIGS. 3a and 3b show a further alternative embodiment of a liquid substrate tank 1 according to the invention, which is designed substantially analogously to the embodiment as per FIGS. 2a to 2d, but with the difference that, here, instead of the horizontally running extraction lines on the base, an extraction probe 20 is provided as extraction line, which extraction probe, in relation to the tank vertical axis, is in this case merely by way of example introduced into the tank interior space 2 from above through the tank roof or the roof wall 19, and is led in the tank interior space 2 as far as into the region of the, by way of example, single extraction channel 12 in this case. The, by way of example, only one single extraction probe 20 in this case is furthermore preferably mounted so as to be adjustable in height, specifically preferably such that, when said tank has been filled with liquid substrate 22, a skirt 21 arranged on the tank roof dips into said liquid substrate, and the extraction probe 20 is led in gas-tight and height-adjustable fashion through the skirt 21 into the tank interior space. It is thus possible for the extraction probe 20 to be mounted and adjusted in the vertical axis direction correspondingly to the arrow 23 in FIG. 3b, which is advantageous in particular if a relatively large amount of substrate-sand mixture 24, which is to be extracted by suction, accumulates in an in particular relatively small-volume liquid substrate tank 1, especially also in the region above the extraction channel 12, as is illustrated merely highly schematically in FIG. 3b.

(32) In this case, too, it is again possible for the extraction probe to be actuated by way of the regulating and/or control device in order to control the extraction, by suction, of the substrate-sand mixture from the extraction channel 12. Then, a corresponding recirculation line 25 leads from the extraction probe 20 to the separator 18, as illustrated by way of example in FIG. 5.

(33) Finally, FIGS. 4a to 4d show a further alternative, fourth embodiment of a liquid substrate tank 1 according to the invention, in the case of which the tank base wall 3 has, in the transition region 3a to the tank side wall 4, multiple mutually spaced-apart, trough-like depressions 26 at the edge, which depressions are in this case for example and preferably uniformly spaced apart from one another and of substantially identical form.

(34) The trough-like depressions 26 are in this case formed in each case by recesses at the edge in the base wall, which recesses have, inwardly toward the tank center, a ramp-shaped bevel 27, which in turn transitions into a base wall region which is adjacent in the direction of the tank center and which is in this case, by way of example, planar. Furthermore, the trough-like depressions 26 are delimited toward the tank outer side by a tank side wall region.

(35) The trough-like depressions 26 are assigned in each case a single extraction line 28, which opens out in a planar trough base region 29 of the respective trough-like depression 26.

(36) In this case, too, the individual extraction lines 28 can be opened and shut off in each case by way of a shut-off element which is separately actuable by the regulating and/or control device.

(37) Furthermore, in this case, all of the extraction lines 28 open into a collecting line 30 which runs as a ring-shaped line in ring-shaped fashion around the liquid substrate tank 1 and which is led to the separator 18 and which can be closed and opened by way of a shut-off element in a manner controlled by way of the control and/or regulating device.

(38) Furthermore, here, the tank base wall 3 has an elevated diverting element 32 in a diverting base wall region 31 which is situated between the trough-like depressions 26, which diverting element narrows inwardly in the direction of the center proceeding from the edge region at the base wall and, here, is furthermore of saddle-roof-shaped or gable-roof-shaped form with a crown edge 33, and has side surfaces 34 which slope downward in each case toward the adjacent trough-like depressions 26.

(39) As can also be seen from FIGS. 4a to 4d, the diverting elements 32, which in this case are preferably of identical form, extend inwardly in the direction of the tank center in each case beyond the trough-like depressions 26, which are formed only in the base wall region at the edge, wherein the liquid substrate tank 1, which has a cylindrical inner contour, and which in this case merely by way of example has a horizontal tank roof 19, has a vertical tank central axis which is formed by a central agitator 35 and toward which the inner ends of the diverting elements 32 are oriented.

(40) The diverting elements 32 may for example be produced from sheet metal, and may for example, as separate components, be fixedly connected to the tank base wall, in particular by way of screw connection.

(41) The central agitator 35 is preferably designed such that, when said central agitator is actuated, the liquid substrate can have imparted to it a cylindrical flow with at least one flow cylinder 36 which moves, in relation to the tank vertical axis, from top to bottom about a horizontal tank axis (see FIG. 4c), with an upward flow 37 at the side of the tank side wall.

(42) With such a construction, it is ensured that the solids contained in the liquid substrate preferentially collect at the edge and then sink downward, wherein the diverting elements 32 advantageously have the effect that the sediments are diverted or conducted in the direction of the trough-like depressions 26, from where they can then be extracted as a substrate-sand mixture via the extraction lines 28 and supplied to the separator 18.

(43) Finally, FIG. 5 shows an exemplary schematic sketch of a separator 18, to which, via the supply line 38, which may for example be connected in terms of flow to the collecting line 17, to the recirculation line 25 or to the collecting line 30 of the different embodiments described above, in order to conduct the substrate-sand mixture, which is extracted from the liquid substrate tank 1 via the respective extraction lines 15 or the extraction probe 20, which likewise forms an extraction line, into the interior space of the separator 18 (arrow 39). Here, the extraction lines are in each case a constituent part of a suction-extraction device which is preferably in the form of a vacuum and/or negative-pressure suction-extraction device, which has a vacuum and/or negative-pressure pump 40 by way of which the pumpable substrate can be extracted, by suction, from the respective extraction channel 12 or from the respective trough-like depression 26 via the respectively opened extraction lines.

(44) The separator 18 may itself furthermore be in the form of a vacuum and/or negative-pressure tank, in which the substrate-sand mixture is received with a pressure lower than atmospheric pressure. In the separator 18, the substrate-sand mixture is separated into a sand phase 41 and a substrate phase 42, wherein the sand phase 41 then accumulates at the base in the separator 18, and there, can be extracted for example in targeted fashion in a manner controlled by opening of a shut-off element 43, which is actuated by the control and/or regulating device. It is likewise possible for the substrate phase 42 to be recirculated as a liquid phase via a recirculation line 44 into the liquid substrate tank 1, which may be realized for example by way of a pump 45 as delivery device. If post-fermentation occurs in the separator 18 and gas forms, said gas can likewise be extracted by way of an extraction line 46 and supplied for a further use.

LIST OF REFERENCE DESIGNATIONS

(45) 1 Liquid substrate tank 2 Tank interior space 3 Tank base wall 4 Tank side wall 5 Foil roof 6 Service shafts 7 Tank central axis 8 Arrows 9a to 9e Agitators 10 Guide mast 11 Pedestal plate 12 Extraction channel 13 Longitudinal sides 14 Transverse sides 15 Extraction lines 16 Shut-off element 17 Collecting line 18 Separator 19 Roof wall 20 Extraction probe 21 Skirt 22 Liquid substrate 23 Arrow 24 Substrate-sand mixture 25 Recirculation line 26 Trough-like depressions 27 Bevel 28 Extraction line 29 Planar trough base region 30 Collecting line 31 Diverting base wall region 32 Diverting element 33 Crown edge 34 Downward-sloping side surfaces 35 Central agitator 36 Flow cylinder 37 Upward flow 38 Supply line 39 Arrow 40 Vacuum and/or negative-pressure pump 41 Sand phase 42 Substrate phase 43 Shut-off element 44 Recirculation line 45 Pump 46 Gas extraction