Biogas plant fermentation tank, service device for attaching to a biogas plant fermentation tank, method for operating a biogas plant fermentation tank

Abstract

To provide a biogas plant fermenter that can achieve high biogas yield while reducing energy consumption despite the presence of a floating layer; and to provide an appropriate service device for the fermenter.SOLUTION: A biogas plant fermenter 1 comprises an essentially liquid substrate 6 contained within a tank interior 5, and at least one stirring device 8 arranged within the tank interior 5. According to the invention, an injection device 9 is provided having at least one delivery pump 10 for pumping the injection fluid 12 and at least one injection nozzle element 11 which is fluidically connected to the at least one delivery pump 10. The injection liquid 12 is injected into the fermenter 1 by means of the injection device 9 in such a way that the injection liquid 12 is injected as a liquid jet 13 from above onto the surface of a floating layer 7 of the substrate 6 and wets the floating layer 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fermentation tank of a biogas plant described in the preamble of claim 1, a service device for attaching to the tank wall of a fermentation tank of a biogas plant described in the preamble of claim 23, a method for operating a fermentation tank of a biogas plant described in the preamble of claim 34, and a biogas plant described in claim 35.

Background Art

[0002] From European Patent Application Publication No. 2497822, a biogas plant fermentation tank equipped with a service device is known. This has a service opening on the cover side that can be hermetically closed by a cover device, a maintenance mast that is height-adjustably guided by a guide mast, and an underwater motor mixer for service work, which essentially pass through the above opening in a sealed state, and these can be taken out of the fermentation tank and returned to the fermentation tank. The ceiling service opening that can be hermetically closed by a cover device is part of a pedestal plate arranged on the ceiling and on which one can walk, and the tank wall of the fermentation tank and a thin roof are connected to the service opening.

[0003] The problem with the fermentation tank of a biogas plant is that, generally depending on the consistency of the type of substrate introduced into the tank, a floating layer or a cover layer that may interfere with the separation or extraction of biogas may be formed. Therefore, it is already known that these floating cover layers are essentially completely destroyed and removed by a stirring device arranged inside the tank at a relatively high energy consumption, and then they are mixed into the substrate. Another drawback in stirring the floating layer by a stirring device arranged inside the tank in addition to the relatively high energy consumption is that the stirring device has to be guided to a very high position where the surface of the substrate exists. This results in a decrease in efficiency with respect to achieving complete mixing, especially when the substrate has a large capacity and is filled to a high position.

[0004] Furthermore, for example, from German Patent No. 102008038262, it is also known to completely omit the use of a stirring device and apply the liquid substrate taken from the bottom of the fermentation tank to the substrate surface via an injection nozzle, and thus to the floating layer and / or the cover layer. This is aimed at keeping the surface of the floating layer, i.e., the uppermost layer, in a wet state. However, this has the drawback that there is no complete mixing of the substrate, and thus the contents of the fermentation tank are not substantially homogenized, so that the fermentation process takes place in an undesirable way in different vertical zones within the fermentation tank.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In contrast, the object of the present invention is to create a biogas plant fermentation tank or a method for operating a biogas plant fermentation tank. Thereby, a high biogas yield can be achieved while suppressing energy consumption despite the presence of a floating layer. Another object of the present invention is to provide a suitable service device for a biogas plant fermentation tank.

Means for Solving the Problems

[0006] This object is achieved by the features of the independent claims. Advantageous improvements are the subject matter of the dependent claims that refer to them.

[0007] According to claim 1, there is proposed a biogas plant fermentation tank, in particular a biogas fermentation tank of a biogas plant having one or more fermentation tanks, in which a substantially liquid substrate is accommodated inside the tank. Further, the biogas plant fermentation tank has at least one stirring device arranged inside the tank. According to the present invention, in addition to at least one stirring device, an injection device having at least one supply pump is provided. Thereby, preferably, the substrate of the fermentation tank or the injection liquid from another fermentation tank of the biogas plant can be drawn in or sucked out. Further, the injection device has at least one injection nozzle element fluidly connected to the supply pump, whereby the injection liquid drawn in or sucked out by the at least one supply pump can be injected into the fermentation tank as a liquid jet. This injection liquid strikes and wets the surface of the floating layer of the substrate from above with respect to the vertical axis direction of the fermentation tank. According to the present invention, at least one stirring device, preferably a plurality of stirring devices spaced apart from each other (e.g., along the circumferential direction of the fermentation tank), can completely homogenize and / or mix the substrate in the region below the floating layer without substantially stirring the floating layer into the substrate.

[0008] In the solution according to the present invention, substantially complete homogenization or mixing of the substrate is carried out in the fermentation tank by the stirring device. This is particularly advantageous for the fermentation process in the substrate and thus for a high biogas yield. These stirring devices preferably comprise mechanical stirrers such as impellers or propellers. These can be driven electrically or hydraulically or pneumatically and do not need to stir within the floating layer. For this reason, these stirring devices can be operated with significantly less energy compared to the case where the floating layer is further broken up by them and mixed into the substrate.

[0009] In the solution according to the present invention, as a result of the fact that the surface of the floating layer is exposed to a liquid jet, and that liquid is aspirated or extracted from the substrate of the fermentation tank or, alternatively or additionally, from another fermentation tank of the associated biogas plant, these floating layers will participate in the fermentation process even without being stirred into the substrate. Due to the jagged surface structure in the floating layer, bacteria in the liquid jet also find a sufficient target surface for an effective fermentation process that increases biogas yield. In the following, even if the present invention is always associated with the aspiration of substrate from the same fermentation tank, i.e., from the fermentation tank in which at least one injection nozzle element is arranged, since this is a preferred embodiment, at this point, in relation to a biogas plant having several fermentation tanks, for example at least one pre-fermentation tank and / or at least one main fermentation tank and / or at least one post-fermentation tank, alternatively or additionally, the injection liquid can be aspirated or recovered from one or more of these further fermentation tanks of the biogas plant. This aspect should clearly be included within the scope of protection of the present invention.

[0010] In the solution according to the present invention, conventional preferably mechanical agitation is combined with an injection device, whereby homogenization or complete mixing of the substrate can advantageously be achieved in the region below the floating layer by means of at least one agitation device, and as a result, a relatively high biogas yield can be obtained with low energy consumption. Furthermore, by wetting the surface of the floating layer and including these floating layers in the fermentation, a further high yield of biogas is achieved.

[0011] As already mentioned above, the at least one agitation device is preferably a mechanical agitation device equipped with, for example, an agitator or an agitation propeller. It is particularly advantageous if a plurality of agitation devices arranged at intervals along the circumferential direction of the fermentation tank are installed or arranged in the fermentation tank in order to essentially completely homogenize or mix the substrate.

[0012] Furthermore, the term "nozzle" in this specification should be interpreted broadly and includes any outlet opening or the shape of the outlet opening. That is, in particular, it should be noted that it includes not only the shape of the outlet opening that is narrowed in the sense of a classical nozzle, but also the shape of a straight or wide outlet opening.

[0013] Furthermore, at least one stirring device is constituted by a stirring device, in particular an underwater motor mixer and / or in particular a stirrer or a propeller, which is arranged in the fermenter and guided by a guide mast for the stirrer arranged in the vertical direction of the tank, and along this guide mast, an embodiment in which the vertical position inside the tank can be adjusted is particularly preferred. By such a stirrer arranged so that its height can be adjusted vertically inside the tank along the guide mast for the stirrer arranged in the fermenter, the substrate arranged in the fermenter is particularly advantageously mixed. This applies, for example, in the case of a large fermenter with a diameter of 10 to 50 m, where several guide masts for stirrers are provided at intervals (for example, in the circumferential direction of the tank), and each stirrer is height-adjustable and is arranged inside the tank in an aligned state in the vertical direction of the tank.

[0014] In a particularly preferred structure, at least one injection nozzle element preferably projects into the tank in an airtight manner with an injection nozzle at the front end, while the rear connection side end of the injection nozzle element is located inside the tank or is arranged outside the tank. Therefore, a particularly simple connection of the supply pump to the injection nozzle element (for example, by a pressure line) is possible, and this connection is also easily accessible for maintenance. Alternatively, at least one injection nozzle element, and thus also its connection side end, can be completely arranged inside the container. This solution is particularly advantageous in relation to a supply pump arranged inside the tank because lines such as the pressure line of the supply pump do not need to be led from outside the fermenter through the wall into the tank.

[0015] According to a particularly preferred specific embodiment, a roof is provided to cover or for covering the tank opening. Although a concrete ceiling can also be used as the roof of the fermentation tank or the opening of the tank, the roof is preferably formed as a thin roof. Further, a service platform is provided which is arranged in the area of the roof and / or forms part of the roof, and this service platform is walkable and is composed of other elements. The service platform is, for example, a walk-on platform plate and / or a horizontal platform plate and is, for example, made of metal (for example, steel, especially stainless steel). This service platform is preferably removably and airtightly connected, preferably to the container wall, especially to the container side wall, by means of at least one connecting element. And the service platform has a roof connection area where the roof is preferably removably and airtightly connected. Further, this service device has at least one injection device. Thus, with such a configuration according to the present invention, the injection device advantageously forms part of the service device having the service platform, thereby forming the service module which can be installed simply and quickly, can be safely installed on site, and can be disassembled for maintenance.

[0016] Particularly advantageous functional integration solutions are obtained when at least one injection nozzle element is arranged and / or held directly on the service platform, preferably in the area of the mounting wall of the service platform. The service platform can furthermore have a mounting wall which preferably projects at an angle from the service platform, for example integrally with the service platform or as a separate element which can be permanently connected or connected to the service platform. The injection nozzle element is preferably arranged and / or held on the mounting wall. In the case of an injection nozzle element which is located inside the tank or arranged outside the tank, at the rear connection-side end, the injection nozzle element can alternatively or additionally have an injection nozzle at its end and can be easily guided through the mounting wall into the tank while being held on the mounting wall. In the case of an injection nozzle element which is provided completely inside, the above is not necessary and simple fixing or folding, for example on the side of the mounting wall facing inside the tank, in the area of the mounting wall on the service platform is sufficient.

[0017] The service platform and / or the mounting wall are preferably made of metal, in particular steel, and here most preferably of stainless steel. Depending on the size and area of the service platform or the mounting wall, the wall thickness can be up to a few centimeters in order to form a stable and accessible service platform or mounting wall.

[0018] The mounting wall projects upward in the direction of the vertical axis of the tank from the service platform, preferably from a substantially horizontal mounting wall connection area of the service platform, and the upper edge area of the mounting wall is located in a roof connection area above the injection nozzle element along the vertical direction of the tank, preferably in at least a partial area of the thin roof connection area. Such an embodiment is particularly preferred. Such a structure of the service platform provides a particularly advantageous possibility of mounting the injection nozzle element on a mounting wall projecting upward from the service platform. This is also characterized in that it is particularly easily accessible to the operator. Furthermore, this upwardly projecting mounting wall is also suitable for a particularly simple and advantageous mounting of an adjacent roof, especially a thin roof. In this case, at the same time, since the injection nozzle element is located under the roof, it is guaranteed to be present inside the tank. Furthermore, this type of upwardly projecting mounting wall makes the possibility of mounting the injection nozzle element relatively high. Thereby, the surface of the floating layer can be easily exposed to the jet of liquid coming from above. This means that a wide range can be achieved in a simple way.

[0019] According to an even more preferred embodiment, the service platform, preferably formed by a walk-on platform plate and / or a flat platform plate, is designed in the form of a trapezoid, preferably an isosceles trapezoid. The first base side of the trapezoid is adjacent to the container wall, particularly the side wall of the container, preferably as the longer base side, and the second base side of the trapezoid is on the opposite side of the first base side, preferably as the shorter base side. The two base sides are connected by inclined leg sides. Thereby, the mounting wall reaches at least partially over the second base side to the two leg sides, and in particular the mounting wall is inclined from the second base side towards the first base side. However, it is preferably inclined downward. Such a geometric structure of the trapezoidal service platform provides a large-area service platform with a mounting wall relatively inside the fermentation tank with respect to the mounting position and can be well integrated into the roof structure, especially a thin roof, and the service platform can also be supported on a wide area in the tank, particularly on the tank side wall.

[0020] For the above reasons, it is particularly advantageous if the injection nozzle element is held on the mounting wall in the region of the second base side, for example, when it is held on the mounting wall and passes through this mounting wall. However, in principle, it is also possible, for example, for at least one injection nozzle element to be arranged with the tank wall, in particular the tank side wall, as the mounting wall instead of the service platform itself. This can occur, for example, when the service platform should not be installed.

[0021] The end of the injection nozzle element having the injection nozzle is preferably coupled to an adjusting device that can operate from the outside of the fermentation tank, whereby the position of the injection nozzle inside the tank can be adjusted, in particular changed. In this way, the position, angle, and impact point of the liquid jet can be advantageously set or changed.

[0022] Specifically, the injection nozzle can be attached to the injection nozzle element by an elastic sleeve-shaped or tubular intermediate member and connected to the guide rod of the adjusting device. In that case, it is preferable that the guide rod is firmly attached above the injection nozzle along the direction of the vertical axis. Next, the guide rod itself is guided outside the fermentation tank through the region of the mounting wall in a play-free and airtight state. The guide rod is attached there in a setting where it can be shifted in the direction of the vertical axis and / or in a lateral direction with respect to the vertical axis and / or in the longitudinal direction of the guide rod. This provides great flexibility with respect to the specific arrangement of the injection nozzle. The elastic tubular intermediate part enables, for example, an injection nozzle having a nozzle opening with a diameter between 30 mm and 90 mm to be displaced relative to the stationary region of the injection nozzle element.

[0023] According to certain embodiments, the pressure line leading away from the supply pump can be connected to the connection-side end of an injection nozzle element located outside or inside the fermentation tank. This enables the supply pump to be placed at a desired location away from the injection nozzle element. The supply pump, of course, has a suction side, by which it can suck out or suck in the essentially liquid substrate received in the fermentation tank.

[0024] Regarding the supply pump, in particular in relation to the arrangement of the connection-side end of the injection nozzle element outside the fermentation tank, there are different arrangement options, which will be described in more detail below.

[0025] According to a particularly preferred first embodiment, the pressure line can lead from the connection-side end of the injection nozzle element, through a pressure line duct, preferably through the pressure line duct of the service platform, to an internal supply pump arranged inside the tank. Such an arrangement of the supply pump inside enables the supply pump to be easily placed at the exact location where it can suck in the desired substrate. In this case, it is even more advantageous if the pressure line is formed by a rigid pressure pipe guided inside the fermentation tank. In that case, it is further preferred that the pressure pipe is supported on the tank wall side, in particular on the tank bottom side, in the pressure line duct and / or in the area inside the tank. This results in an overall stable structure, so that the internal supply pump is connected and / or held to the rigid pressure pipe in a functionally reliable state. Such a structure with a rigid pressure pipe is, of course, also suitable for connection to the rear connection-side end of the injection nozzle element arranged in the layer.

[0026] As an alternative to this, at least one sub - area of the pressure line, preferably a pressure line located inside the tank, can be designed as a pressure line with a variable shape and / or length, in particular as a flexible or extensible pressure line. This is particularly advantageous when the internal supply pump is arranged inside the fermentation tank and guided in a height - adjustable manner along a supply - pump guide mast aligned in the direction of the vertical axis of the tank. Such a structure with a height - adjustable supply pump advantageously allows the supply pump to be arranged at different heights. Furthermore, due to the height adjustment, the substrate can be easily accessed, facilitating the maintenance of the supply pump. The supply - pump guide mast can be supported, for example, on a service platform and / or can be supported, and at the same time, can also be supported inside the tank, for example, on the tank wall side, such as the tank bottom side. Such a structure is, of course, suitable for both the connection to the rear - connecting - side end of the injection - nozzle element arranged inside or outside the tank.

[0027] An embodiment is particularly preferred in which the part of the service platform adjacent to the pressure - line duct of the service platform has a service opening for the supply pump for access to the internal supply pump, which can be hermetically closed by a cover member.

[0028] According to a further alternative embodiment, the pressure line can be led from the connecting side end of the injection nozzle element to an external supply pump arranged outside the fermentation tank, and the suction side of the supply pump is led to a suction connection of the tank wall, in particular of the tank side wall, or is guided through the tank wall, in particular through the tank side wall, into the interior of the fermentation tank and has at least one suction line. The advantage of such an external supply pump arranged outside the fermentation tank is in particular the easy accessibility. However, in this case, it is necessary to connect to the interior of the fermentation tank. For this purpose, according to a further particularly preferred embodiment, several suction connections are provided at different heights, in particular essentially in a row and spaced apart in the direction of the vertical axis of the fermentation tank, as seen in the direction of the vertical axis of the fermentation tank. These suction connections are arranged on the tank side wall and are preferably connected to the suction side of the external supply pump in a valve-controlled state. Thereby, it is possible to draw out the substrate from different heights or to connect, for example, a plurality of suction lines for different injection nozzle elements simultaneously.

[0029] In this regard, an external supply pump and an internal supply pump can be provided in parallel. These supply pumps can also be connected to, for example, a plurality of injection nozzle elements or one injection nozzle element, in which case it is necessary to provide corresponding switching valves.

[0030] According to a further particularly preferred embodiment, the service platform has, in addition to the service opening of the supply pump in particular, a service opening of the stirrer which can preferably be closed airtight by a cover member, through which service opening an adjustable-height stirring device in the stirrer guide mast is accessible for maintenance and service work, and / or the stirring device can preferably be removed from the fermentation tank and returned into the fermentation tank in an essentially airtight state. This also represents a great advantage in that maintenance and service work on the stirring device can be easily carried out, and the stirring device can be easily moved into the region of the service opening and preferably also outside the fermentation tank.

[0031] The cover member that airtightly closes each service opening can be formed by at least one cover and / or by a mast housing that protrudes upward from the service opening to form a receiving space at the upper part of the mast of each guide mast. For example, according to a particularly preferred deployment, the guide mast, i.e., the guide mast for the supply pump and / or the guide mast for the stirring device, is taken out upward from the fermentation tank through the service opening with respect to the vertical axis direction of the tank equipped with the mast top. The service opening is airtightly covered by a cover and an adjacent mast housing that protrudes beyond the plane of the cover. The mast housing has at least one side wall and is open at the bottom towards the fermentation tank. Preferably, for example, together with the upper wall of the box-shaped mast housing, it constitutes a bearing for the mast top. The side wall or at least one side wall of the mast housing is designed as an openable maintenance wall. Here, in the openable lower region of the maintenance wall, since a cover that can also be opened is adjacent, the maintenance wall and the cover can be opened. As a result, the stirring device, or alternatively the supply pump, can be lifted from the fermentation tank above the height of each service opening.

[0032] Furthermore, a sealing element is preferably arranged around the service opening. When in the sealed position, this sealing element protrudes like a shaft into the interior of the fermentation tank, particularly during maintenance work and service work contained in the fermentation tank. This sealing element immerses in the liquid substrate to be fermented and airtightly separates a gas phase region surrounded by a ring by the sealing element that is above the substrate under the openable service opening from the remaining gas phase region inside the fermentation tank. Such a structure enables the maintenance work and service work of the supply pump brought into the area of the service opening or the stirring device brought into the area of the service opening to be carried out in a particularly reliable manner. This is because no undesired large amount of gas leaks from the service opening.

[0033] Particularly preferably, in relation to such a structure, the sealing element is provided in relation to a structure in which the sealing element is formed by a rigid, non-displaceable and non-flexible pipe socket-shaped collar that permanently protrudes from the service opening towards the inside of the fermentation tank vessel.

[0034] Using such a sealing element creates a more functional integration for individually installable components in relation to the service platform, can be used flexibly as a service module, and can itself be easily replaced or removed.

[0035] Furthermore, this service platform can have at least one edge region that is in airtight contact connection with the tank side wall and is firmly attached to the tank side wall. For example, the edge region can here be firmly attached to the tank side wall by a screw connection. The screw connection ensures a removable connection. This allows, for example, the service platform to be easily disassembled again in relation to replacement work or maintenance work on the service platform.

[0036] As already described above, it is also particularly advantageous to support the service platform, especially a large-area service platform, from below by a support device. This support device can be constituted, for example, by a support that is mechanically coupled to the lower side of the service platform and is guided by the tank side wall and / or the tank bottom wall, for example, to support the service side wall.

[0037] If the roof is to be a thin roof, it is preferable that this thin roof, especially the edge region of the thin roof, is airtight, especially clogged, by a clamping connection between a clamping region, especially an edge flange of the service platform, and a clamping strip that can be removably connected to the clamping region.

[0038] Furthermore, according to the present invention, a service device or service module for attachment to the tank wall of a biogas plant fermenter is claimed. This service device or service module has a service platform that can be arranged in the area of the fermenter roof, especially the area of a thin roof. This service platform is preferably removably and airtight-fixable, especially by at least one connecting element on the tank wall, especially by the side wall of the fermenter, and the service platform has a roof connection area that can connect to the roof, preferably a foil roof. The service platform, preferably formed by a walk-on platform plate and / or a flat platform plate, has a service opening for the agitator that can be closed by a cover member that is preferably airtight, and through this service opening, access to the agitator can be obtained for maintenance work and service work. The agitator can be removed from the fermenter through this opening and then reinserted into the fermenter. The agitator and / or the agitator guide mast associated with the agitator also form part of the service device according to a particularly preferred embodiment. According to the present invention, at least one injection nozzle element in the injection device is preferably also arranged on the area of the attachment wall of the service platform and / or supported on the service platform. The injection device preferably further has at least one supply pump, which is part of the service device. By this supply pump, an injection liquid, preferably an injection liquid from the substrate of the fermenter or an injection liquid from another fermenter in another biogas plant, can be suctioned or discharged and conveyed to at least one injection nozzle element.

[0039] At least one assembled injection nozzle element preferably protrudes into the tank interior in an airtight state, and an injection nozzle is provided at the tip of the injection nozzle element to inject the injection liquid into the interior of the fermenter, and the rear connection side end of the injection nozzle element is arranged outside the tank interior.

Advantages of the Invention

[0040] Therefore, according to the present invention, such a service device forms a service module and an assembly module, and these modules also have at least one functional part of the injection device in addition to at least one functional part in the stirring device. As a result, a flexible and highly integrated service device including a plurality of functional parts is obtained, thereby enabling simple and functionally reliable maintenance for each functional part.

[0041] Furthermore, there is a high degree of flexibility regarding possible applications, for example, in relation to retrofit solutions. Furthermore, there is a high degree of flexibility regarding possible applications, for example, in relation to retrofit solutions. The same also applies to the dependent claims regarding the service device, which refer to the service device according to the present invention in a form that includes preferred embodiments. Here too, refer to the above description regarding the advantages brought about thereby.

[0042] Regarding the service device, the indication "in the vertical axis direction" means a reference to the installation state of the service device or the service platform. That is, it means the arrangement in the vertical axis direction of the tank.

[0043] Furthermore, a method is also claimed. The advantages obtained in relation to the method according to the present invention are the same as the advantages of the biogas plant fermenter as already explained above. In this regard, to avoid repetition, refer to the description made for the biogas plant fermenter.

[0044] A biogas plant including at least one biogas plant fermenter is also claimed.

Brief Description of the Drawings

[0045]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0046] In FIG. 1, a schematic view is schematically shown as an example, in which the structure and operation mode of a biogas plant fermentation tank according to the present invention are illustrated in more detail by way of example.

[0047] In FIG. 1, a biogas plant fermentation tank 1 of a biogas plant not shown is shown. This has, in addition to the biogas plant fermentation tank 1, optionally at least one further fermentation tank, that is, the biogas plant fermentation tank 1 comprises a pre, main, or post-fermentation tank of the biogas plant. This fermentation tank 1 has a tank bottom wall 2 and preferably a cylindrical tank side wall 3, and its upper side, and thus the ceiling side, is covered here by a thin roof 4 shown only schematically and in principle. In this regard, the fermentation tank 1 has a conventional structure.

[0048] The substantially liquid substrate 6 to be fermented is accommodated in the tank interior 5. The substrate 6 is formed by a liquid such as, for example, fertilizer, in which there are solids such as straw that have a relatively strong tendency to float. As a result, on the surface of the substrate 6, there is a floating layer or cover layer 7, which is only schematically shown here and has a surface structure with regular unevenness. In the tank interior 5, for example, two mechanical stirrers with stirring blades, which form the stirring device 8, are arranged. These stirring devices 8 (of course, only a single stirring device 8 can also be provided) are designed and arranged in the tank interior 5 such that the substrate 6 is present essentially or preferably only in the region below the floating layer and the floating layer is stirred without being taken into the substrate and is completely homogenized and / or mixed.

[0049] Furthermore, an injection device 9 is provided here. This injection device 9 has, here by way of example, two supply pumps 10 (it is also possible to provide only a single supply pump 10), whereby a certain amount of the substrate is sucked out of the fermentation tank 1 as the injection liquid. However, alternatively or additionally, the substrate can also be sucked out from other fermentation tanks of the associated biogas plant in a way not shown here. In this case, at least one supply pump is arranged in or above the other fermentation tank so that it can suck the substrate of the other fermentation tank.

[0050] The injection device 9 also has injection nozzle elements 11 fluidly connected to the respective supply pumps 10, by means of which injection nozzle elements 11, the injection liquid 12 sucked out by at least one supply pump can be injected into the fermentation tank 1 or into the interior 5 of the tank. At that time, the injection liquid 12 impinges as a liquid jet 13 on the surface of the floating layer 7 of the substrate 6 from above with respect to the vertical axis direction of the tank, wetting the floating layer 7. As already explained in connection with the supply pump 10, the arrangement of a total of two injection nozzle elements 11 is to be understood here merely as an example. Of course, it is also possible to provide only a single injection nozzle element 11. It is likewise possible to provide only one supply pump 10 supplying several injection nozzle elements 11. In principle, it is possible to provide only a single injection nozzle element 11 fluidly connected to several supply pumps 10. The supply pump 10 can potentially suck in the substrate from different regions or different heights when viewing the tank in plan view and / or from different fermentation tanks in the biogas plant.

[0051] By wetting the floating layer 7 with the substrate from the fermentation tank 1, it is advantageously achieved that the floating layer 7 itself is also included in the fermentation process and thus in the biogas production. Thereby, it is no longer necessary to destroy and stir the floating layer 7 as before. By additionally arranging at least one stirring device 8, substantially complete mixing and thus homogenization of the substrate below the floating layer 7 is simultaneously achieved, as schematically indicated by the arrow 14, which also helps to achieve a high biogas yield. A particular advantage of operating the stirring device 8 without the need to crush or stir the floating layer 7 is that substantially complete homogenization or mixing can be achieved with relatively little energy consumption with only the liquid substrate 6, i.e. without a floating layer. Thus, the energy consumption of the stirring device 8 operated according to the invention is significantly lower than the energy consumption of a stirring device in which the floating layer is destroyed and stirred.

[0052] The liquid jet 13 of the injection nozzle element 11 is set as a function of the delivery pressure applied via the nozzle opening and the supply pump 10, such that, in particular, the floating layer 7 is preferably not completely destroyed, and the surface of the floating layer 7 is wetted as desired. Particularly preferably, the surface of the floating layer 7 is merely acted upon such that it is more cracked in order to provide an enlarged attack surface for bacteria from the sprayed substrate.

[0053] As can be seen from FIG. 1, there are different options for arranging the injection device 9 and the stirring device 8. As schematically and only in principle shown in FIG. 2, depending on the size of the fermenter 1, preferably when viewed in the circumferential direction, a plurality of identical and / or different stirring devices 8 or injection nozzle elements 11 can be arranged at a distance. FIG. 2 also schematically shows that the individual stirring devices 8 can also have different sizes and thus different stirring forces can be achieved. The stirring device 8 can in principle be a separate stirrer, which is introduced into the tank interior 5 as a separate unit from the side or from above with respect to the vertical axis of the tank in each case. Alternatively, these stirring devices 8 can be part of the service device 15, as will be described in detail below in connection with a further exemplary embodiment.

[0054] As shown in connection with FIG. 2, the injection device 9 can also be at least partially a component of such a service device 15, or, as also shown in FIG. 1, it can be formed by a separate unit installed independently of such a service device 15. For example, the front end of the injection nozzle element 11 having the injection nozzle 16 is preferably installed on the tank side wall 3 so as to project into the tank interior 5 in an airtight manner. On the other hand, the rear connection side end 18 of the injection nozzle element 11 is located or arranged outside the tank interior 5, where it is prepared and easily accessible for connection to the pressure line 19 of the supply pump 10. This pressure line 19 can be designed as a flexible or rigid pressure line in the same way as the suction line 20 located upstream of the supply pump 10 is designed to have flexibility or rigidity. The suction line 20 can lead to the suction connection 21 on the tank side wall 3 or can also lead into the interior of the fermenter 1 through the tank side wall 3.

[0055] In the schematic principle diagram of FIG. 1, the supply pump 10 is shown, by way of example only, as an external supply pump 10 arranged outside the fermenter 1. As will be explained in more detail in the following figures, the supply pump 10 can also be arranged inside the tank interior 5.

[0056] FIGS. 3 and 4 show a particularly preferred embodiment or variant according to the invention, comprising a service device 15 having a service platform 22 that can be arranged in the region of the thin roof 4 shown in FIG. 3. This is also formed here only by way of example by a walk-on platform and a flat platform. This service platform 22 has an edge region 23. This edge region 23 is here, by way of example only, placed on an airtight contact connection on the tank side wall 3 and is removably or firmly connected to the airtight contact connection, for example by a screw connection. In particular, although very schematic, as can be seen from FIG. 4, the service platform 22 can also be supported from below by a support device formed by a support frame 24. The support frame 24 is, here by way of example only, supported inside the tank side wall 3.

[0057] The service platform 22 here is, for example, in the shape of a trapezoid, preferably an isosceles trapezoid, and the first base side forms the longer base side (the lower base of the trapezoid), forms the edge region 23, and is connected to the tank side wall 3. The second base side 26 facing the first, longer base side 25 forms the shorter base side (the upper base of the trapezoid). The two base sides 25, 26 are connected by the inclined leg sides 27, 28.

[0058] As can also be seen from FIGS. 3 and 4 which are schematic views, the service platform 22 has a mounting wall 29 that protrudes upward in the vertical axis direction of the tank. The protruding direction is, for example, at a right angle. This mounting wall 29 here extends across the entire second base side 26 as just an example and essentially completely extends across the two leg sides 27, 28. The height of the mounting wall slopes downward from the second base side 26 to the first base side 25. As very schematically shown by the dashed line in FIG. 3, the mounting wall with the upper end region 30 forms at least part or all of the thin roof connection region 31 on the service platform side, and on it, the thin roof 4 is preferably made airtight and is preferably fixed by a releasable clamp connection.

[0059] As can also be seen from FIGS. 3 and 4, here, the injection nozzle element 11 is held, for example, in the region of the mounting wall 29 on the second base side 26, and the front end having the injection nozzle 16 penetrates the mounting wall 29 so as to be preferably airtight. And the injection nozzle element 11 protrudes into the tank interior 5. In contrast, the rear connection side end portion 18 of the injection nozzle element 11 is outside the tank interior 5 above the service platform 22 and is thus very easily accessible for connecting the pressure line 19.

[0060] In the embodiment of FIGS. 3 and 4, the pressure line 19 is designed as a rigid pressure line that starts from the connection side rear end to the supply nozzle element 11, passes through the pressure line duct 32 of the service platform, and is led to the internal supply pump 10 arranged inside the tank.

[0061] The pressure line 19 formed by the rigid pressure pipe is supported here in the region of the pressure line duct 32 and further, for example, on the bottom side of the tank.

[0062] As can be seen particularly from FIG. 4, the internal supply pump 10 is directly connected to and supported by the rigid pressure pipe as the pressure line 19 here. Thereby, the supply pump 10 directly sucks the supply liquid through its suction side and conveys it to the supply nozzle element 11 through the pressure pipe as the pressure line 19.

[0063] The injection nozzle 16 is connected to the injection nozzle element here by an elastic tubular intermediate part 33 (FIGS. 3 and 4) 33 which is shown only very schematically here. This intermediate part 33 can be an elastomer hose and is connected to the guide rod 34 of the adjusting device 35. Here, the guide rod 34 is engaged or connected to the upper part of the injection nozzle 16 with respect to the vertical axis direction of the tank.

[0064] The guide rod 34, not shown in detail here, is guided out of the fermentation tank 1 in an airtight state through the mounting wall region via an elastomer sleeve in a play state and is supported there by the link 36 of the adjusting device 35. That is, displacement of the guide rod 34 in the vertical axis direction and / or in the direction transverse to the vertical axis and / or in the longitudinal direction of the guide rod is possible, and thus the front end 17 having the injection nozzle 16 can be arranged at different positions, for example, so as to change the injection angle.

[0065] As can be seen particularly from FIG. 3, the service platform 22 has a service opening 37 for the supply pump, particularly as an inspection opening, immediately adjacent to the pressure line duct 32 of this service platform 22. This is illustrated here only exemplarily by a cover 38 as a cover device and is closed airtight. When the cover 38 is removed, access to the internal supply pump 10 is possible via the service opening 37 for the supply pump.

[0066] As can be seen schematically from FIGS. 3 and 4, the service platform 22 also has a service opening 39 for the stirrer, which can be closed airtight by a cover device to be described in more detail below. Thereby, access is possible to the height-adjustable stirrer guided by the stirrer guide mast 40 as the stirring device 8, or it can enter and exit the fermentation tank 1 in an essentially airtight state. The stirring device 8 is designed here, for example, as an underwater mixer with stirring blades. In this regard, all stirring devices can be operated electrically, pneumatically or hydraulically in a known manner. The same applies to the supply pump 10.

[0067] In connection with the height-adjustable underwater mixer, the height adjustment can be carried out in a manner known per se, for example using a cable winch or the like. In FIG. 4, a pull rope 41 acting on the underwater mixer can only be seen by way of example.

[0068] As can also be seen from FIGS. 3 and 4, the agitator guide mast 40 is guided in the upper mast part in the vertical axis direction of the tank, upward from the fermentation tank 1 through the agitator service opening 39. The agitator service opening 39 is hermetically covered by a cover 42 and an adjacent mast housing 43 protruding above the surface of the cover 42. Here, the mast housing 43 has several side walls, is open at the bottom towards the inside 5 of the tank, and forms a bearing 45 for the upper mast part at the ceiling wall 44. The side wall 46 of the mast housing 43 is designed as an openable maintenance wall, is adjacent to the cover 42 in the lower region, and the cover 42 can also be opened. Thereby, the openable side wall (maintenance wall) 46 and the cover 42 can be opened, and the stirring device 8 can be lifted upward from the inside 5 of the tank beyond the level of the agitator service opening 39.

[0069] As can be seen particularly from FIG. 4, a sealing element is arranged as a gas apron 47 around the agitator service opening 39, which, in the closed position, protrudes into the inside 5 of the fermentation tank like a shaft. This is immersed in the liquid substrate to be fermented accommodated in the fermentation tank 1, at least during maintenance and service operations, in a way not shown here. And the gas phase region annularly surrounded by the gas apron above the substrate under the openable agitator service opening 39 is hermetically separated from the remaining gas phase region in the inside 5 of the tank. Here, the gas apron 47 is formed, for example, by a rigid, displacement-inhibiting and non-flexible pipe socket-shaped collar that permanently protrudes from the agitator service opening 39 in the direction of the inside 5 of the fermentation tank.

[0070] In connection with the supply pump service opening 37 and the agitator service opening 39, different possibilities for the configuration of the cover device for each service opening have been described in detail here by way of example. Needless to say, as described in connection with the supply pump service opening 37, the agitator service opening 39 can be hermetically closed only by a cover.

[0071] On the one hand, as described in more detail in connection with the service opening 39 for the agitator, instead of the cover 38 of the service opening 37 for the supply pump, a cover 42 and a mast housing 43 can also be provided. This is particularly advantageous when the internal supply pump 10 is designed as a functional part guided in a height-adjustable manner in the direction of the vertical axis of the tank by the supply pump guide mast 48, as shown only very schematically in FIG. 5. This is because the supply pump 10 can also be lifted above the level of the service opening 37 for the supply pump. In this case, the pressure line 19 located inside the tank 5 or at least a part of this pressure line 19 is designed as a pressure line with variable shape and / or length, in particular as a flexible or telescopic pressure line. The height adjustment of the supply pump 10 along the supply pump guide mast 48 can be carried out, for example, via a pull rope that can be wound around or unwound from a cable winch, similar to the height adjustment of the underwater mixer by the agitator guide mast 40.

[0072] However, in FIG. 5, a variant regarding the displaceability of the internal supply pump 10 is shown in connection with the cover 38 as a cover device, as described in more detail above in connection with FIGS. 3 and 4.

[0073] In FIG. 5, on the one hand, the support frame 24 is shown only very schematically and in principle by a dashed line. Also, schematically and by a dashed line, the agitator guide mast 40 is shown together with the underwater mixer as the agitator device 8. However, in FIG. 5, for the sake of clarity, the mast housing 43 for this agitator guide mast 40 is not shown.

[0074] The above description shows that there are different options for designing the service platform 22 of the service device equipped with the cover device for the service opening. Thus, the corresponding desired variations are selected according to the application and purpose. Furthermore, here, it is of course also possible to provide a cover with a mast housing associated with the supply pump guide mast 48, especially in relation to the height-adjustable supply pump 10. Regarding the service opening 39 for the stirrer, it should also be mentioned that it is only the cover corresponding to the cover 38 in FIGS. 3 and 4.

[0075] Needless to say, the gas apron 47 can also be provided for the service opening 37 for the supply pump, especially in relation to the variant of the height-adjustable supply pump shown in FIG. 5, even if not explicitly shown.

[0076] Another alternative embodiment is shown in FIG. 6, where, for example, in the form of a flexible pressure line, which is preferably in the form of a variable shape and / or variable length pressure line, starting from the rear end 18 on the connection side of the injection nozzle element 11, a pressure line 19 is provided that extends to the outside of the fermentation tank 1 where the external supply pump is arranged (see also FIG. 1). The suction side of the pressure line 19 has a suction line 20 that leads to the suction connection 21 on the tank side wall 3. As can also be seen from FIG. 6, several suction connections 21, which are arranged at different heights in the vertical axis direction of the tank, can be provided on the tank side wall, especially in the form of suction connections 21 that are essentially stacked in a row and spaced apart in the vertical axis direction. Since these suction connections 21 can be connected to the suction line 20 of the external supply pump 10, the supply pump can be arranged at different heights with respect to the substrate. However, alternatively, for example, different suction lines of different supply pumps can also be connected to different suction connections 21, which leads to different injection nozzle elements 11. FIG. 6 also does not show the mast housing 43 for the stirrer guide mast 40 for clarity. Needless to say, alternatively, other embodiments without the mast housing 43 are of course possible, for example, as described in connection with the service opening 37 for the supply pump, the service opening 39 for the stirrer can be hermetically closed only with a cover.

[0077] FIG. 7 shows a further embodiment, which is an alternative to the embodiment of FIG. 5, but with the supply nozzle element 11 being completely arranged inside the tank 5. Here too, the injection nozzle element 11 is held on the service platform 22, preferably on the mounting wall 29, for example in the region of approximately the second base side 26. Access to the injection nozzle element can here be effected, for example, via the service opening 37 or, alternatively or additionally, via an inspection opening in the mounting wall 29 not shown here. The connecting side end 18 of the injection nozzle element 11 located inside the fermenter 1 is also connected to a pressure line 19 leading away from the internal supply pump 10. Such a completely internal arrangement is of course possible in connection with other configurations and arrangements for the pressure line and / or the supply pump, for example in connection with the non-height-adjustable internal supply pump 10 and / or in connection with the rigid pressure tube as the pressure line 19 shown in the embodiments of FIGS. 3 and 4. For the sake of clarity, the mast housing 43 for the agitator guide mast 40 is also not shown in FIG. 7. Needless to say, of course, other embodiments without the mast housing 43 are also possible here, for example, as described in connection with the service opening 37 for the supply pump, the service opening 39 for the agitator can be hermetically closed only with a cover.

Claims

1. A biogas plant fermentation tank (1), in which a substantially liquid substrate (6) is received inside the tank (5), comprising at least one stirring device (8) arranged inside the tank (5), an injection device (9) is provided, the injection device (9) has at least one supply pump (10), and is configured such that the supply pump (10) can suck the injection liquid (12), the injection device (9) has at least one injection nozzle element (11), and this injection nozzle element (11) is fluidly connected to the at least one supply pump (10), and can inject the injection liquid (12) sucked out by the at least one supply pump (10) into the fermentation tank (1), the opening of the tank is covered by a roof (4), a service device (15) having a service platform (22) is provided, the service platform (22) is arranged in the area of the roof (4) and / or is provided so as to form part of the roof (4), on which one can walk, is formed by separate parts, is connected to the tank wall by at least one connecting element, and has a roof connection area (31) to which the roof (4) is connected, the service device (15) further includes at least one of the injection devices (9), the injection device (9) is characterized in that at least one of the injection nozzle elements (11) is arranged and / or held on the service platform (22). A fermentation tank as claimed in claim 1.

2. The fermentation tank according to claim 1, wherein at least one stirring device (8) is constituted by a submerged motor stirring device, is arranged in the fermentation tank (1), and is arranged so as to be guided in a manner adjustable in height inside the tank (5) along a stirrer guide mast (40) arranged in the direction of the vertical axis of the tank.

3. At least one injection nozzle element (11) having a front end portion (17) with an injection nozzle projects into the tank interior (5), and the rear connection side end portion (18) of the injection nozzle element (11) is arranged outside the tank interior (5) or at least one injection nozzle element (11) is completely arranged within the tank interior (5). The fermenter according to claim 1, characterized in that.

4. The service platform (22) is removably and airtightly connected to the tank wall by at least one connecting element, The service platform (22) has a roof connection area (31) to which the roof (4) is removably and airtightly connected. The fermenter according to claim 1, characterized in that.

5. The service platform (22) has a mounting wall (29) projecting at an angle from the service platform (22). The fermenter according to claim 1, characterized in that.

6. The mounting wall (29) projects upward from a mounting wall connection area that extends substantially horizontally in the service platform (22) when viewed in the direction of the vertical axis of the tank, and The mounting wall (29) having an upper edge area (30) located above the injection nozzle element (11) along the vertical axis of the tank forms at least a part of the roof connection area (31). The fermenter according to claim 5, characterized in that.

7. The service platform (22) is formed by a walk-on platform plate and / or a flat platform plate and is designed in a trapezoidal form, The first base side (25) is adjacent to the tank wall, The second base side (26) is located on the opposite side of the first base side (25), The inclined leg sides (27, 28) connect the two base sides (25, 26), The mounting wall (29) extends along the second base side (26) and at least partially along the areas of the two leg sides (27, 28). The fermenter according to claim 1, characterized in that. Claim 8 The fermenter according to claim 7, characterized in that the injection nozzle element (11) is held in the region of the second base side (26) of the mounting wall (29). Claim 9 The fermenter according to claim 1, characterized in that the end (17) of the injection nozzle element (11) having the injection nozzle (16) is connected to an adjusting device, which can be operated from the outside of the fermenter (1) and by which the position of the injection nozzle (16) inside the tank can be adjusted. Claim 10 The fermenter according to claim 3, characterized in that the pressure line (19) leading away from the supply pump (10) is connected to the connecting side end (18) of the supply nozzle element (11) located outside or inside the fermenter (1). Claim 11 The fermenter according to claim 10, characterized in that the pressure line (19) leads from the connecting side end in the injection nozzle element (11) to an external supply pump (10) arranged outside the fermenter (1), and the suction side of this supply pump (10) has at least one suction line (20) leading to a suction connection (21) provided in the tank wall. Claim 12 The fermenter according to claim 1, characterized in that the service platform (22) has a service opening (39) for the stirrer, which can be closed by a cover member, and is accessible via the opening (39) to a height-adjustable stirrer guided by a stirrer guide mast (40) for maintenance and service work, and / or the stirrer is removable from the fermenter (1) and can be returned into the fermenter (1). Claim 13 Around the service opening (39), a sealing element (47) protruding downward into the tank interior (5) like a shaft is arranged in the sealing position. This sealing element (47) is immersed in the liquid substrate (6) for fermentation in the fermentation tank (1) at least during maintenance work and service work, and a gas phase region ringed by the sealing element (47) below the openable service opening (39) and above the substrate (6) is hermetically separated from the remaining gas phase region of the tank interior (5). The fermentation tank according to claim 12, characterized in that.

14. A method for operating a fermentation tank of a biogas plant, Substantially liquid substrate (6) is received into the tank interior (5), At least one stirring device (8) is arranged in the tank interior (5), The injection liquid (12) is sucked by an injection device (9) equipped with at least one supply pump (10), and the injection liquid (12) is conveyed to at least one injection nozzle element (11) of the injection device (9), By the injection nozzle element (11), the injection liquid (12) sucked by at least one feed pump (10) is injected into the fermentation tank (1), and this injection liquid (12) is made to collide from above with the surface of the floating layer (7) of the substrate (6) as a liquid jet (13) along the direction of the vertical axis of the tank to wet this floating layer (7), When covering the opening of the tank with the roof (4), A service device (15) having a service platform (22) is used. The service platform (22) is arranged in the region of the roof (4) and / or is provided so as to form a part of the roof (4), on which one can walk, is formed by separate parts, is connected to the tank wall by at least one connecting element, and has a roof connection region (31) to which the roof (4) is connected, As the service device (15), at least one injection device (9) in which at least one injection nozzle element (11) is arranged and / or held on the service platform (22) is further used, At this time, by means of at least one stirring device (8), the substrate (6) in the region below the floating layer (7) is substantially completely homogenized and / or mixed without stirring the floating layer (7) into the substrate (6), which is a method for operating a fermentation tank of a biogas plant.

Images