EP3956432A1

EP3956432A1 - Plug flow fermenter for a biogas plant

Info

Publication number: EP3956432A1
Application number: EP20715780.1A
Authority: EP
Inventors: Michael Niederbacher
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-04-16
Filing date: 2020-03-20
Publication date: 2022-02-23
Also published as: DE102019109999A1; US20220213419A1; WO2020212073A1

Abstract

The invention relates to a plug flow fermenter (1) for a biogas plant, comprising a reactor container (2) embodied as longitudinal straight tubes. A substrate that is to be fermented, preferably by dry fermentation, can be fermented in the form of a plug flow with production of biogas. inside the reactor container (9). The reactor container (2) has at least one container inlet (10), via which the substrate to be fermented can be fed to the inside of the reactor (9), and at least one container outlet (12) that is arranged at a distance from the container inlet (10) in the direction of flow (x) of the plug flow, via which container outlet the fermented substrate can be discharged from the inside the reactor (9). A plurality of mixing devices (19) that are can be exchanged separately, are arranged inside the reactor container (9) when seen in the longitudinal direction of extension and thus in the direction of flow of the plug flow.

Description

description

Plug flow fermenter for a Bioqasanlaqe

The invention relates to a plug flow - term enter for a biogas plant according to the preamble of claim 1, a biogas plant according to claim 25 and a method for generating biogas according to the preamble of claim 26.

There are basically two methods used in practice to generate biogas, namely wet fermentation and dry fermentation. The fundamental difference between wet fermentation and dry fermentation is that the dry matter content in the area of the fermenter inlet in wet fermentation is regularly between 9 and 14%, while that of dry fermentation is higher and is usually> 25%. The process temperatures for wet fermentation are mostly around 37 ° C (mesophilic), while they are mostly around 55 ° C (thermophilic) for dry fermentation.

The advantage of dry fermentation or dry fermentation is that with it comparatively dry, fibrous and contaminated biomass, such as biowaste, organic fractions from residual waste, manure and green waste, which are problematic to process in wet-fermenting biogas plants, can be processed to produce biogas to create. In dry fermentation, substrates that do not compete with food production can be used to generate biogas.

There are different process variants for dry fermentation, a basic distinction being made between the discontinuous or batch-wise processes and the continuous processes. In the discontinuous process a fermentation tank (a so-called garage fermenter) is filled with the substrate to be fermented, which is then fermented until the end of the predetermined residence time. A mechanical, hydraulic or pneumatic mixing of the fermenter contents is not necessary. The temperature control and inoculation with methane bacteria takes place here via the recirculation of the percolate that occurs during the process. As soon as the dry fermentation process is completed, the fermenter tanks are ventilated, whereby the resulting air-methane mixture is drawn off and cleaned via a biofilter. In such a discontinuous dry fermentation process, the substrate is only added at the beginning of the fermentation process and the material introduced is then completely fermented. Such biogas plants are usually modular and have several fermenter tanks in order to achieve a more or less uniform gas production.

In contrast to the discontinuous processes, in the continuous dry fermentation process, similar to the wet fermentation process, the substrate is introduced continuously or at intervals into the reactor or fermenter container. So-called plug flow fermenters are used for the continuous processing of substrates in the context of dry fermentation, in which the substrate is conveyed through the fermenter as a plug, preferably in conjunction with the use of hydraulic piston pumps. Such a plug flow fermenter is known from DE 44 16 521 A1. The fermenter is specifically designed here as a horizontal cylindrical fermenter with a reactor container designed as an elongated, straight tube. In the two opposite end walls of the reactor vessel, an axis of rotation of an agitator is mounted in the middle. On this axis of rotation agitator arms are arranged at regular, axial intervals. A similar structure is also known from EP 3 450 536 A1.

These known dry fermenters have the disadvantage that when maintenance work is carried out regularly on the agitator, the entire fermenter operation must always be stopped and the fermenter emptied in order to be able to maintain the agitator or to be able to remove and replace the agitator. This is also the case if only some of the stirring paddles are damaged. The maintenance effort in such fermenters is therefore considerable and thus uneconomical and expensive.

In contrast, it is the object of the present invention to provide a plug flow fermenter for a biogas plant with a reactor vessel designed as an elongated, straight tube, by means of which the maintenance and repair of stirring devices can be carried out in a technically simple manner and without disruptive and expensive interruptions in operation. Another object of the present invention is to provide a biogas plant with such a plug flow fermenter. And finally, it is a further object of the present invention to provide a method for producing biogas with such a plug flow fermenter.

This object is achieved with the features of the independent patent claims. Advantageous refinements are the subject of the dependent claims which refer back to them.

According to claim 1, a plug flow fermenter is provided for a biogas plant, which has a reactor container designed as an elongated, straight tube, in the reactor interior of which a substrate to be fermented, preferably by dry fermentation, can be fermented as a plug flow with biogas generation, the reactor container having a container inlet , via which the substrate to be fermented in the reactor interior can be fed, and has a container outlet spaced from the container inlet in the plug flow direction, via which the fermented substrate can be discharged from the reactor interior. In the interior of the reactor there are also a plurality of separate stirring devices spaced apart in the longitudinal direction of the reactor vessel and thus in the plug flow flow direction, by means of which the substrate can be locally circulated and / or by means of which the substrate can be conveyed in the plug flow direction. According to the invention, the agitating devices or at least one of the agitating devices is designed as an exchangeable agitating device which, in particular also when filled Reactor container and / or during operation of the plug flow fermenter, can be removed from the reactor interior and / or inserted into the reactor interior, preferably removed from the reactor interior from above and / or inserted into the reactor interior as viewed in the vertical axis direction is.

This means that the entire fermenter operation no longer has to be stopped during maintenance work on the "agitator" (formed by the several separate stirring devices) and the reactor vessel does not have to be emptied first in order to carry out maintenance work on the stirring devices. By dividing the stirring work into several independent or separate stirring devices, these can preferably be serviced or exchanged individually without the stirring work of the other stirring devices being impaired, so that the fermentation operation can be maintained. The separate stirring devices can thus easily be removed or inserted individually during ongoing operation, which means that biogas plants with plug flow fermenters according to the invention can be operated highly efficiently and economically.

As already mentioned above, the reactor vessel is designed as an elongated, straight, lying tube, that is to say advantageously and particularly preferably designed as a completely straight tube that runs in a straight direction and is not curved. The term tube means in particular that the reactor container is designed to be hollow on the inside in order to form the reactor interior, and can be formed, for example, by a round cylinder made of steel, for example. Particularly preferred, however, is a concrete, simple design of the reactor vessel that can be manufactured, for example from concrete, as a cuboid delimited by six rectangles forming the reactor vessel walls and thus has six side faces that are at right angles to one another, the ones in the longitudinal direction or linear direction opposite end walls are just as parallel as the side walls opposite each other in the transverse direction and the bottom and top wall opposite each other in the vertical axis direction. With the structure according to the invention, in which a plurality of interchangeable stirring devices spaced apart and exchangeable as seen in the plug flow direction are arranged in the reactor interior, a desired plug flow can also be implemented functionally reliably and without great effort.

In principle, especially in the case of very wide or large plug-flow fermenters, several stirring devices can also be arranged side by side in the transverse direction.

According to a preferred embodiment, the stirring devices can be designed at least in part essentially the same and thus form identical parts, which is also particularly advantageous with regard to maintenance and assembly.

Furthermore, the stirring devices can in principle have a different distance from one another in the plug flow direction of flow. However, a configuration in which the stirring devices are evenly spaced from one another is particularly preferred. Such a uniform spacing enables a plug flow to be achieved in a particularly functionally reliable manner.

The stirring devices are particularly preferably oriented approximately vertically with respect to the reactor vessel lying in a horizontal plane, although an arrangement inclined to the vertical, that is to say inclined or angled, is of course also possible in principle. However, the approximately vertical alignment of the stirring devices in relation to the reactor vessel lying in the horizontal plane enables particularly simple assembly and arrangement of the stirring devices, in particular with a further particularly preferred embodiment, according to which the reactor vessel has an upper ceiling wall viewed in the vertical axis direction, which is preferably accessible and / or preferably at least partially flat.

According to a particularly advantageous embodiment, the reactor vessel, preferably the top wall of the reactor vessel, can have an assembly opening have through which the stirring device can be introduced into the reactor interior and / or removed from the reactor interior with at least a partial area. The assembly opening ensures simple removal and simple insertion of the stirring device in a defined, predetermined manner. The assembly opening thus serves as a service opening through which the stirring device can be introduced into the interior of the reactor simply and functionally reliably from outside the reactor vessel and can also be removed from there again. In this context, it can then preferably be provided that the exchangeable stirring device extends through the assembly opening with a sub-area received in the installed state in the reactor interior in a substantially gas-tight manner and protrudes over a sub-area located outside the reactor vessel in the installed state. This then also provides easy access from the outside.

In particular in the case of relatively large assembly openings which are not completely filled and thus essentially sealed by the agitator device carried out, for example a agitator shaft of an agitator device, the assembly opening can also be made using a one-piece or multi-part and / or removable cover, preferably made of stainless steel , be essentially gas-tight closable. The cover can be formed by a separate component. However, an embodiment is particularly preferred in which the cover is part of the stirring device and closes the respectively associated assembly opening when the stirring device is inserted and installed. Furthermore, it can alternatively or additionally be provided that the replaceable stirring device in the assembled state extends through the cover with a partial area accommodated in the reactor interior in a substantially gas-tight manner and protrudes over a partial area located outside the reactor vessel in the mounted state.

The at least one exchangeable stirring device also preferably has a stirring shaft with at least one stirring blade, which is guided from outside the reactor vessel through the assembly opening into the interior of the reactor, it is preferably provided that the assembly opening is dimensioned so that the stirring shaft passes through it, preferably together at least one on the agitator shaft arranged agitator blade, can be inserted into the reactor interior and / or can be removed from the reactor interior. The assembly opening thus serves here specifically as a service opening through which the agitator shaft together with the agitator blades arranged there can be easily and functionally safely introduced into the reactor interior, for example from the ceiling wall, and also removed from there.

For a particularly advantageous gas-tight structure, the agitator shaft extends through the cover in a substantially gas-tight manner.

According to a further advantageous embodiment, it is proposed that the agitator shaft be assigned a preferably raised and / or funnel-shaped bearing receptacle, preferably made of steel, in particular stainless steel, on the bottom side in the reactor vessel, by means of which the free agitator shaft end is rotatably connected or in the assembled state which the free end of the agitator shaft is rotatably received. The connection is preferably designed as a plug-in rotary connection. This enables each agitator shaft to be supported and stored in a simple and precisely positioned manner in the reactor vessel.

In addition, according to a particularly advantageous embodiment, it is proposed that the agitator shaft can be driven by an actuating device, for example a drive motor, which is arranged outside the reactor vessel and preferably supported and / or held on the top wall. This results in a particularly compact, function-integrated structure of a stirring device together with an advantageous support for the same. An electric drive motor or a pneumatically or hydraulically operated drive motor is suitable as the drive motor.

A further embodiment is particularly advantageous in which, on the side of the assembly opening facing the reactor interior, an apron, preferably made of stainless steel, protrudes from the assembly opening in the direction of the reactor interior, surrounds the assembly opening in a ring and plunges into the substrate in the sealing position . This apron ensures that the interchangeable Stirring devices, for example a stirrer shaft together with the stirrer blades arranged thereon, can be brought in or out of the interior of the reactor essentially in a gas-tight manner or without an unnecessarily large loss of gas. This skirt can basically be formed integrally with the reactor vessel, but is preferably formed by a separate component and, for example, fixed from below on the opening edge area around the assembly opening. Alternatively, however, the apron can also be hooked into the assembly opening from above and supported or held in the opening edge area around the assembly opening. To fix the apron, it has a flange area, for example, which then rests against the opening edge area either from below or from above. The apron is also preferably fixed using detachable screw connections so that the apron can also be exchanged if necessary and replaced with a new apron. In the case of the presence of a flange area, the apron is then detachably fixed by means of the screw connection over this at the opening edge area.

According to a further particularly preferred embodiment, the assembly opening is designed in the form of a slot and preferably extends in the area between two reactor vessel wall areas lying opposite in the transverse direction

Reactor vessel side walls, which is particularly advantageous in connection with agitator blades extending away from the agitator shaft on opposite sides, because here the agitator shaft and agitator blades can be easily brought in and out without folding the agitator blades in or out.

The mounting openings and / or the covers are preferably designed essentially the same and / or, viewed in the direction of longitudinal extent of the reactor vessel, lie in a straight line or in a straight line spaced one behind the other and / or are aligned parallel to one another.

According to a particularly preferred specific embodiment, it is provided that the agitating device (s) each have a plurality of agitator blades extending away from the agitator shaft on opposite sides and lying in a vertical plane has or have. With such a structure, a particularly simple introduction and removal of the agitator shaft together with the agitator blades is possible without folding the agitator blades in or out. This is preferably done in such a way that, on a first side of the agitator shaft, several agitator blades, viewed in the vertical axis direction, protrude one above the other and at a distance from the agitator shaft, and that on an opposite, 180 ° spaced second side of the agitator shaft, several agitator blades, viewed in the vertical axis direction, also protrude one above the other and at a distance from one another protrude from the agitator shaft, it is preferably provided that the agitator blades on the second side are offset in the vertical axis direction with respect to the agitator blades on the first side.

According to a further particularly preferred embodiment according to the invention, a bottom-side collecting channel, in particular a sand collecting channel, is assigned to at least some of the stirring devices. The term “assigned” is to be interpreted in a broad sense and means that such a collecting channel can basically be located essentially on the bottom side below the respective agitator device or agitator shaft. However, this terminology is also intended to include configurations in which the collecting channel is arranged, for example in the middle, between two stirring devices spaced apart in the flow direction of the plug flow. In connection with the collecting channels on the bottom, it is only essential that material to be withdrawn from the interior of the reactor, in particular a substrate-sand mixture as material to be withdrawn, collects therein, in particular when an "assigned" stirring device is operated. The term drainage channel is also to be understood in a broad sense and is also intended to include large-scale drainage devices, for example a drainage shaft as a drainage channel. Furthermore, in connection with this embodiment, an extraction device is provided, by means of which the material that collects in the collecting channel can be withdrawn from the at least one collecting channel. Such a configuration ensures that the material to be withdrawn and deposited in the interior of the reactor collects in a defined manner in the collecting channels, from where it can be withdrawn in a functionally reliable manner. Furthermore, a separator can be provided to which the material withdrawn by means of the withdrawal device is fed and in which the withdrawn material, preferably the substrate-sand mixture already mentioned, can be separated into a substrate phase and a waste phase, in particular a sand phase. Particularly preferred in this context is a configuration in which a return device is also provided, by means of which the substrate phase separated in the separator can be fed to the reactor interior as percolate, namely preferably fed to the substrate from above as percolate viewed in the vertical axis direction. Such a return device is expressly only provided as an option, that is, in principle, only a separator can be provided, so that the percolate then has to be fed to the substrate in the interior of the reactor in a different manner, for example in order to inoculate the substrate. The term separator is expressly to be interpreted broadly here and is also expressly intended to include configurations such as a settling basin.

Furthermore, the discharge device preferably has a discharge line led to each collecting channel, the discharge lines opening into a collecting line which is led to the separator. A component of the extraction device is also at least one conveyor device, for example a extraction pump, by means of which the material to be separated can be withdrawn from the collecting channels and conveyed into the separator. In addition, locking elements, for example valves, can be provided by means of which the trigger is controlled at certain times. Analogously to this, the return device can be designed with a return line, at least one delivery device, such as a pump, and a blocking element, such as a valve, in order to control the return functionally reliable at certain times.

In particular as an alternative, but possibly also in addition to a collecting channel or collecting shaft solution as described above, it can also be provided that a plurality of discharge lines spaced apart in the longitudinal direction are provided on the reactor vessel, which form a discharge device and which, preferably through a lateral or outer wall of the reactor vessel through, in the bottom, lower area of the Reactor interior are guided so that a material to be withdrawn, in particular a substrate-sand mixture, can be withdrawn from the reactor vessel via this. Here, too, it can then be provided, for example, that the discharge lines open into a collecting line. Such an arrangement may help to avoid chutes and chutes. Here, too, the withdrawn material can then be fed to a separator or settling basin, analogous to the solution described above in connection with the collecting channels or collecting shafts, either directly from the individual exhaust lines or indirectly via a collecting line connecting the exhaust lines to a separator or settling basin, in which the withdrawn material, preferably the aforementioned substrate-sand mixture can be separated into a substrate phase and a waste phase, in particular a sand phase.

The at least one container inlet and the at least one container outlet are preferably arranged at end regions of the reactor container that are opposite in the flow direction, preferably end walls that are spaced apart from one another and aligned parallel to one another in the longitudinal direction of the reactor container.

The reactor vessel can in principle have any cross-sectional shape. However, an embodiment is particularly preferred in which the walls of the reactor vessel, viewed in cross section through the reactor vessel, form a frame surrounding the interior of the reactor. The walls of the reactor vessel preferably form a rectangular reactor interior, based on the cross section through the reactor vessel. Such a reactor vessel is easy to manufacture, for example from concrete or stainless steel.

The plug flow fermenter according to the invention also preferably has at least one gas extraction device by means of which the biogas formed in the interior of the reactor can be extracted from the reactor container. It is particularly preferred here that at least one gas discharge line of the gas discharge device is routed into the interior of the reactor in the region of the container outlet. This ensures that the biogas is safely discharged into the Area ensured in which the fermentation process and thus the biogas production is or are essentially complete. Here, too, it goes without saying that the gas extraction device can of course have an extraction line that is coupled to a delivery device, such as a pump, whereby controllable valves can again be provided as blocking elements, by means of which the biogas extraction is controlled according to the respective needs becomes.

Furthermore, a feed device, for example a feed screw, is preferably provided, by means of which the substrate to be fermented can be fed to the reactor interior via the at least one container inlet in a functionally reliable manner.

Furthermore, the plug-flow fermenter according to the invention can have a discharge device for a functionally reliable discharge of the fermented substrate from the reactor interior, by means of which the fermented substrate can be discharged via the container outlet. For example, such a discharge device can be formed by a discharge pump as a delivery device.

More preferably, the plug stream -Ferm enter has a control device by means of which the feed into and the discharge from the reactor vessel and thus the residence time of the substrate in the reactor vessel can be controlled or regulated. The control or regulation is preferably carried out in such a way that the residence time in the reactor vessel is between 25 and 50 days. Such a dwell time has proven to be particularly advantageous in order to achieve effective biogas generation with a high biogas yield in connection with a plug flow -erm enter according to the invention.

The substrate to be fermented, preferably by dry fermentation, particularly preferably has a dry matter content of 12 to 40% DM, preferably 19 to 30% DM, in the reactor vessel.

The advantages that can be achieved with the biogas plant according to the invention or with the process control according to the invention correspond to those of the plug flow Fermenter. In this respect, reference is made to the previous statements to avoid repetition.

The invention is explained in more detail below with reference to a drawing.

Show it:

1 schematically shows a perspective illustration of an exemplary

Embodiment of a plug flow fermenter according to the invention,

FIG. 2 shows a schematic, perspective exploded view with regard to the essential components of FIG. 1,

3 schematically shows a top view of the fermenter according to FIG. 1 with a partially omitted top wall,

FIG. 4 schematically shows a side view of a portion of the exemplary fermenter according to the invention according to FIG. 1 with the side wall omitted, and FIG

5 schematically shows a schematic diagram with two alternatives

Possibilities for fastening the apron, the left half of the picture showing a first design and the right half of the picture showing an alternative, second design.

In Fig. 1, a perspective representation of an exemplary embodiment of a plug flow fermenter 1 according to the invention is shown schematically, which is, for example, part of a biogas plant not shown here. As can be seen in particular from FIG. 2, which shows a schematic exploded view of the essential components of the plug flow fermenter 1 of FIG. 1, and from FIG. 3, the plug flow fermenter 1 has an elongated, straight tube Reactor vessel 2 on. This reactor vessel 2 is merely an example of the shape of a container or cuboid and has a first or front end wall 3 and a second or rear end wall 4 opposite in the longitudinal direction of extension x of the reactor vessel and thus in the plug flow direction. The reactor vessel 2 also has two side walls 5 and 6 opposite one another in the transverse direction y and a bottom wall 8.

As can also be seen from FIGS. 1 to 4, the reactor vessel 2 also has an upper, preferably flat, top wall 7 opposite the bottom wall 8 in the vertical axis direction z. The reactor vessel 2 is thus designed here, for example, as an elongated, straight parallelepiped which is delimited by six rectangles forming the reactor vessel walls 3, 4, 5, 6, 7 and 8 and thus has six side surfaces that are at right angles to one another, with the end walls 3, 4 opposite in the longitudinal direction x or linear direction are just as parallel as the side walls 5, 6 opposite each other in the transverse direction y and the top wall 7 and bottom wall 8 opposite each other in the vertical axis direction z. The walls 5, 6, 7 and 8 of the reactor vessel 2 here also form, based on the cross section (sectional plane yz) through the reactor vessel 2, a rectangular reactor interior 9, which is to be understood only as an example. Of course, the reactor vessel can also have other internal and also other external geometries, for example be at least partially rounded at the internal and / or external corners, in order to form a more circular or oval cross-section, for example. Semicircular cross-sections are also conceivable, to name just one further example.

The reactor vessel 2 is shown lying down, which also corresponds to its most common use, which is why such fermenters are also called horizontal fermenters. The walls of the fermenter can be made of any suitable material, for example concrete or stainless steel.

The reactor container 2 here has, for example, a container inlet 10 in the area of the first end wall 3, via which a substrate to be fermented is continuously or fed by means of a feed device, which is designed here as a feed screw 11, for example certain times can be supplied in intervals. By pressing in the substrate, preferably at the same time a feed force for the plug flow is generated in its flow direction, which corresponds to the longitudinal direction x of the reactor vessel 2.

Furthermore, a container outlet 12 is provided on the opposite second end wall 3 of the reactor container 2, via which the fermented substrate can be discharged from the reactor interior 9 by means of a discharge device designed as a discharge pump, for example.

In the interior of the reactor 9 there is also a plurality of stirrer devices 19 spaced apart as seen in plug flow direction x, by means of which the substrate to be fermented can be locally circulated and / or by means of which the substrate can be conveyed in plug flow direction x.

The stirring devices 19 are preferably designed essentially the same and, moreover, are preferably evenly spaced from one another.

The stirring devices 19 are also oriented vertically with respect to the lying reactor vessel 2, i.e. in the vertical axis direction z, and here, by way of example, each have a stirring shaft 20 guided from outside the reactor vessel 2 through the top wall 7 with several stirring blades 21 spaced apart in the longitudinal direction of the stirring shaft.

Specifically, the stirring device 19 here has, for example, several stirring blades 21 extending away from the stirring shaft 20 on opposite sides and lying in a vertical plane (see in particular FIGS. 2 and 4), with several stirring blades 21 one above the other on a first side of the stirring shaft 20 as seen in the vertical axis direction and protrude from the agitator shaft 20 at a distance from one another and, on an opposite, 180 ° spaced second side of the agitator shaft 20, a plurality of agitator blades 21 also protrude from the agitator shaft 20, viewed in the vertical axis direction, one above the other and at a distance from one another. As can also be seen here, the agitator blades 21 are the second side here, for example, offset in the vertical axis direction z with respect to the agitator blades 21 of the first side.

As can also be seen in particular from the figures, the stirring devices 19 also each have an actuating device, for example a drive motor 22, which is arranged outside of the reactor vessel 2 and is supported and held on the top wall 7 by means of a supporting device 15. The agitator shaft 20 can be driven in rotation by means of the drive motor 22. The support device 15 is formed here by way of example by a frame carrying the drive motor 22 with a plurality of support feet 14 which are arranged around the agitator shaft 20 and fan out towards the bottom.

As can be seen in particular from FIG. 1 in conjunction with FIGS. 2, 3 and 4, the top wall 7 has, in the area of the agitator shaft lead-through, a mounting opening 24 that can be closed in a gas-tight manner by means of a cover 23 preferably made of stainless steel, the agitator shaft 20 being the Cover 23 extends through each gas-tight. The assembly openings 24 are also dimensioned in such a way that the agitator shaft 20, together with the agitator blades 21, can both be brought into and out of the reactor interior 9 through them. For this reason, the mounting openings 24 extend here, for example, in the manner of a slot, essentially over the entire width of the top wall 7, that is in the transverse direction y between the side walls 5 and 6. The mounting openings 24 are also further in a straight line or in a, viewed in the longitudinal direction x rectilinear alignment spaced one behind the other and are preferably all of the same design and / or aligned parallel to one another. The same then also applies here to the covers 23 in their assembled state.

On the side of the assembly opening 24 facing the reactor interior 9 there is also an apron 25, which projects from the installation opening 24 in the direction of the reactor interior 9, surrounds the installation opening 24 in a ring and, in the sealing position, dips into the substrate 16, preferably a stainless steel apron, arranged (see in particular Figure 4). This apron 25 is preferably formed by a separate component and can, for example, as in FIG. 5, the left half of the picture shown, are fixed from below on the opening edge area around the mounting opening 24. Alternatively (right half of FIG. 5), however, the apron 25 can also be hooked into the assembly opening 24 from above and supported or held in the opening edge area around the assembly opening 24. To fix the apron 25, in both alternative embodiments it preferably has a flange area 25a which rests in the opening edge area (from below in the first alternative of the left half of the figure and from above in the second alternative of the right half of the figure). The fixing of the apron 25 via its flange area 25a takes place here by way of example and specifically preferably via releasable screw connections 13 so that the apron can also be exchanged and replaced with a new apron if necessary.

As is shown in FIG. 1 only by way of example and schematically and with dashed lines, at least some of the stirring devices 19 are assigned a bottom-side collecting channel 26 in which, in particular when the stirring devices 19 are actuated, material 17 to be withdrawn from the reactor interior 9 ( see Figure 4), in particular a substrate-sand mixture, accumulates. Merely by way of example, the collecting channels 26 are each arranged at a distance between two stirring devices 19, the collecting channels 26 extending here further, for example, in the transverse direction y between the side walls 5 and 6. The collecting channels 26 can be designed, for example, as trough-shaped depressions, into each of which a discharge line 27 opens, which in turn is part of a discharge device, by means of which the material 17 accumulating in the respective collecting channel 26 can be drawn off from the collecting channel 26.

The discharge lines 27 open here, for example, into a collecting line 28, via which the withdrawn material is fed to a separator 29 of the extraction device, in which the withdrawn material, preferably a substrate-sand mixture, is divided into a substrate phase and a waste phase, preferably a sand phase, is separated. A return line 30 of a return device then leads from the separator 29 back to the reactor container 2, so that the substrate phase separated in the separator 29 can be fed to the reactor interior as percolate, preferably fed to the substrate from above as percolate, viewed in the vertical axis direction z can. This is shown in FIG. 1 merely by way of example and schematically by means of a plurality of percolate lines 18 branching off from the return line 30. It goes without saying that only a single percolate line or a different number of percolate lines can also be provided.

As an alternative to this solution with the collecting channels just described, provision can also be made, if necessary, not to provide any collecting channels 26 and instead to provide only a plurality of discharge lines 27 spaced apart from one another along or around the reactor vessel 2. These discharge lines 27 then form a discharge device and are here, for example, led through the side wall 5 of the reactor vessel 2 into the bottom area of the reactor interior 9, so that a material 17 to be withdrawn, in particular a substrate-sand mixture, can be drawn off over them , withdrawn from the reactor vessel 2 and fed to the collecting line 28. Via this, the withdrawn material is fed to the separator 29 analogously to before, in which the withdrawn material, preferably a substrate-sand mixture, is separated into a substrate phase and a waste phase, preferably a sand phase. Possibly. The solution just described and the solution with collecting channels can also be implemented together, so that two types of drainage lines 27 are then provided, namely drainage lines 27 that are routed to the collecting channels 26 and drainage lines 27 that are not routed to the collecting channels 27. In the latter case, one A collecting line 28 can be provided for all of the drain lines 27 or two collecting lines 28 can be provided, that is to say one collecting line 28 for each of the different types of drain lines 27.

The dosing of the biomass, the discharge of the biomass, the actuation of the stirring devices, the removal of the material from the collecting channels 26 (if present) and the return of the substrate to the reactor container 2 take place here each controlled by means of a control device, not shown. By means of this control device, in particular the feed into and the discharge from the reactor container 2 and thus the residence time of the substrate in the reactor container 2 are controlled and regulated. The control or regulation is preferably carried out in such a way that the residence time in the reactor vessel 2 is between 25 to 50 days and / or that the substrate in the reactor vessel 2 has a dry matter content of 12 to 40% DM, preferably 19 to 30% DM.

Furthermore, a gas extraction device 31 is provided, by means of which the biogas (methane gas) produced can be extracted from the reactor container 2.

If a stirring device 19 or a plurality of stirring devices 19 are to be replaced while the plug flow fermenter 1 is in operation, i.e. when the reactor vessel 2 is full or full, this can be done in a simple manner with the present invention by Stirring device 19 provided for replacement, as shown schematically and by way of example in FIG. 4 from the right using the second stirring device 19, is simply lifted out through the assembly opening 24. In addition, as shown by way of example in FIG. 4, it is particularly advantageous (but not absolutely necessary) if the substrate 16 in the reactor interior 9 has such a filling height in the vertical axis direction z that the skirt 25 dips into the substrate 16, since then an essentially gas-tight state is established in the area of the assembly opening 24, which enables the cover 23 to be opened and the stirring device 19 to be lifted or removed without any significant gas escaping from the assembly opening 24 or from the reactor vessel 2. The same applies, of course, in an analogous manner to reinstalling the or a new stirring device 19.

As can also be seen from Figure 4, the lifted agitator 19 has been rotated here with respect to the agitator blades 21 spaced 180 ° so that the agitator blades 21 are aligned in the direction of the slot-shaped assembly opening 24 and thus the agitator shaft 20 together with the Agitator blades 21 can be introduced into the reactor interior 9 as well as brought out very easily.

The agitator shafts 20 are assigned on the bottom side in the reactor vessel 2, that is, on the inside of the bottom wall 8, a bearing mount 20a, preferably made of steel, in particular stainless steel, which is raised here by way of example and optionally also widens upwards in a funnel shape (not shown) the free agitator shaft end 20b is rotatably received in the assembled state, it is preferably provided that the connection is designed as a plug-in rotary connection.

The one-part or multi-part cover 23 can, as shown in the figures, be part of the agitator device 19 and, when the agitator device 19 is inserted and installed, can close the associated assembly opening 24, preferably in a gas-tight manner. As an alternative to this, the cover 23 can in principle also be formed by a separate component which can be handled independently of the stirring device 19. In this case, the cover is then, for example, made in several parts in order to be able to arrange it around the agitator shaft 20 in a simple and gas-tight manner.

In both variants just mentioned, the cover 23 can be arranged in the area of the assembly opening 24, for example resting on the edge area, so that the cover 23 can also be fixed to the surrounding reactor vessel wall area by means of releasable fastening means.

Claims

1. Plug flow fermenter (1) for a biogas plant, with a reactor vessel (2) designed as an elongated, straight tube, in the reactor interior (9) of which a substrate to be fermented, preferably by dry fermentation, can be fermented as a plug flow with biogas generation, wherein the reactor container (2) has at least one container inlet (10), via which the substrate to be fermented can be fed to the reactor interior (9), and at least one container outlet (12) spaced apart from the container inlet (10) in the plug flow direction (x), via which the fermented substrate can be discharged from the reactor interior (9), and wherein a plurality of separate stirring devices (19) are arranged in the reactor interior (9), which are spaced apart in the longitudinal direction of the reactor vessel and thus in the plug flow direction of flow which the substrate can be circulated locally and / or by means of which the substrate can be conveyed in the plug flow direction (x) t, characterized in that the agitator devices (19) or at least one of the agitator devices (19) is designed as an exchangeable agitator device which, especially when the reactor vessel (2) is full and / or when the plug-flow fermenter (1) is in operation, from the The reactor interior (9) can be removed and / or inserted into the reactor interior (9), preferably seen in the vertical axis direction from above from the reactor interior (9) and / or can be inserted into the reactor interior (9) .

2. Plug flow fermenter according to claim 1, characterized in that the agitating devices (19) are at least partially designed essentially the same and / or that the agitating devices (19) are at least partially evenly spaced from one another.

3. Plug flow fermenter according to claim 1 or 2, characterized in that the stirring devices (19), based on the reactor vessel (2) lying in a horizontal plane, are aligned approximately in the direction of the axis of the floch and thus approximately vertically or aligned inclined to the vertical are.

4. Plug flow fermenter according to one of the preceding claims, characterized in that the reactor vessel (2) has an upper, preferably accessible and / or preferably at least partially flat, ceiling wall (7), viewed in the direction of the vertical axis.

5. Plug flow fermenter according to one of the preceding claims, characterized in that the reactor vessel (2), preferably the top wall (7) of the reactor vessel (2), has an assembly opening (24) through which the stirring device (19) at least with a partial area can be introduced into the reactor interior (9) and / or removed from the reactor interior (9), whereby it is preferably provided that the exchangeable stirring device (19) has the mounting opening (24) with an in the assembled state in the reactor The sub-area accommodated in the interior (9) extends through essentially gas-tight and protrudes over with a sub-area lying outside the reactor vessel (2) in the assembled state.

6. plug flow fermenter according to claim 5, characterized in that the mounting opening (24) by means of a one-piece or multi-part and / or removable cover (23), preferably made of stainless steel, is essentially gas-tight, it is preferably provided that the cover (23) is part of the stirring device (19) and / or that the exchangeable stirring device (19) the cover (23) in the In the assembled state, a sub-area received in the reactor interior (9) extends through essentially gas-tight and protrudes over with a sub-area lying outside the reactor container (2) in the assembled state.

7. Plug flow fermenter according to claim 5 or 6, characterized in that the at least one exchangeable stirring device (19) has a stirring shaft (20) guided from outside the reactor container (2) through the assembly opening (24) into the reactor interior (9) with at least one agitator blade (21), it is preferably provided that the assembly opening (24) is dimensioned such that the agitator shaft (20) passes through it, preferably together with the at least one agitator blade (21) arranged on the agitator shaft (20) , can be inserted into the reactor interior (9) and / or removed from the reactor interior (9).

8. plug flow fermenter according to claim 6 and 7, characterized in that the agitator shaft (20) extends through the cover (23) essentially gas-tight.

9. plug flow fermenter according to claim 7 or 8, characterized in that the agitator shaft (20) on the bottom side in the reactor vessel (2) is assigned a preferably raised and / or funnel-shaped bearing receptacle (20a), by means of which the free agitator shaft end (20b) is rotatably connected in the assembled state or in which the free agitator shaft end (20b) is rotatably received in the assembled state, it is preferably provided that the connection is designed as a plug-in rotary connection.

10. Plug flow -Ferm enter according to one of claims 7 to 9, characterized in that the agitator shaft (20) is arranged outside of the reactor vessel (2), preferably on the top wall (7) supported and / or held, actuating device (22) , preferably an electrically or pneumatically or hydraulically operated drive motor, can be driven.

11. plug flow fermenter according to one of claims 5 to 10, characterized in that on the reactor interior (9) facing side of the assembly opening (24) from the assembly opening (24) in the direction of the reactor interior (9) protruding, The apron (25), preferably made of stainless steel, which surrounds the assembly opening (24) essentially in a ring shape and dips into the substrate in the sealing position, is arranged.

12. plug flow fermenter according to claim 11, characterized in that the skirt (25) is formed by a separate component and in

Floch axis direction (z) seen from below, preferably with a flange area (25a), on which the opening edge area around the assembly opening (24) is fixed, preferably by means of a detachable

Screw connection (13) is set on the opening edge area.

13. plug flow fermenter according to claim 11, characterized in that the skirt (25) is formed by a separate component and in

Viewed from above in the direction of the vertical axis (z), it is suspended in the assembly opening (24) and, preferably with a flange area (25a), is supported or held on the opening edge area around the assembly opening (24), preferably by means of a releasable screw connection (13) on the Opening edge area is set.

14. Plug flow fermenter according to one of claims 5 to 13, characterized in that the assembly opening (24), in particular in connection with agitator blades (21) extending away from the agitator shaft (20) on opposite sides, is slot-like and is located in the Area between two opposite reactor container wall areas in the transverse direction, preferably reactor container side walls, it is preferably provided that all assembly openings (24) are formed essentially the same and / or in a straight line when viewed in the longitudinal direction (x) of the reactor container (2) Line are spaced one behind the other and / or are aligned parallel to one another.

15. Plug flow fermenter according to one of claims 7 to 14, characterized in that the agitating device (19) has a plurality of agitator blades (21) extending away from the agitator shaft (20) on opposite sides and lying in a vertical plane, preferably such that on a first side of the agitator shaft (20) several agitator blades (21), viewed in the direction of the vertical axis, protrude one above the other and at a distance from the agitator shaft (20) and that on an opposite second side of the agitator shaft (20) which is 180 ° apart, also several agitator blades (21 ) protrude from the agitator shaft (20), viewed in the vertical axis direction, one above the other and at a distance from one another, whereby it is preferably provided that the agitator blades (21) on the second side are offset in the vertical axis direction from the agitator blades (21) on the first side.

16. Plug flow fermenter according to one of the preceding claims, characterized in that at least some of the stirring devices (19) are assigned a bottom-side collecting channel (26), in particular a sand collecting channel, in which, in particular when the stirring device ( 19), material to be withdrawn from the reactor interior (9), in particular a substrate-sand mixture, collects, and that a discharge device is provided by means of which the material that collects in the collecting channel (26) is removed from the at least one collecting channel (26 ) is removable.

17. Plug flow fermenter according to one of the preceding claims, characterized in that a plurality of discharge lines (27) spaced apart in the longitudinal direction are provided on the reactor vessel (2), which form a discharge device and which, preferably by a lateral or outer wall (3) of the reactor vessel (2) through, into the bottom, lower region of the reactor interior (9), so that a material to be withdrawn, in particular a substrate-sand mixture, can be withdrawn from the reactor container (2) via this, whereby it is preferably provided that the discharge lines (27) open into a collecting line (28).

18. Plug flow fermenter according to claim 16 or 17, characterized in that a separator (29) is provided to which the material withdrawn by means of the withdrawal device can be fed and in which the withdrawn material, preferably a substrate-sand mixture, is in a substrate phase and can be separated into a waste phase, preferably a sand phase, wherein a return device (30) is preferably provided, by means of which the substrate phase separated in the separator (29) can be fed to the reactor interior (9) as a percolate, preferably to the substrate viewed in the vertical axis direction can be supplied from above as a percolate.

19. Plug flow fermenter according to one of the preceding claims, characterized in that the at least one container inlet (10) and the at least one container outlet (12) at opposite end regions in the flow direction, preferably in

End walls (3, 4) of the reactor vessel (2), which are spaced apart from one another and aligned parallel to one another, in the longitudinal direction (x).

20. Plug flow fermenter according to one of the preceding claims, characterized in that the walls of the reactor vessel (2), seen in cross section through the reactor vessel (2), form a frame surrounding the reactor interior (9), preferably rectangular.

21. Plug flow fermenter according to one of the preceding claims, characterized in that at least one gas extraction device (31) is provided, by means of which the biogas formed in the reactor interior (9) can be extracted from the reactor container (2), it is preferably provided that at least one gas discharge line of the gas discharge device (31) is led into the reactor interior (9) in the region of the container outlet (12).

22. Plug flow fermenter according to one of the preceding claims, characterized in that a feed device (11), preferably a feed screw, is provided, by means of which the substrate to be fermented can be fed to the reactor interior (9) via the container inlet (10), and / or that a discharge device (13), preferably a discharge pump, is provided, by means of which the fermented substrate can be discharged from the reactor interior (9) via the container outlet (12).

23. Plug flow fermenter according to one of the preceding claims, characterized in that a control device is provided by means of which the feed into and the discharge from the reactor vessel (2) and thus the residence time of the substrate in the reactor vessel (2) can be controlled or regulated , is preferably controllable or regulatable in such a way that the residence time in the reactor vessel (2) is between 25 to 50 days.

24. Plug flow fermenter according to one of the preceding claims, characterized in that the substrate to be fermented, preferably by dry fermentation, has a dry matter content of 12 to 40% DM, preferably 19 to 30% DM.

25. Biogas plant with a plug flow fermenter according to one of the preceding claims.

26. A method for generating biogas with a plug flow fermenter according to one of claims 1 to 24 or with a biogas plant according to claim 25, with a reactor container (2) designed as an elongated, straight tube, in the reactor interior (9) of which, preferably by dry fermentation, the substrate to be fermented is fermented as a plug flow with biogas generation, the reactor container (2) having at least one container inlet (10) through which the substrate to be fermented is fed to the reactor interior (9), and at least one in the plug flow direction ( x) has a container outlet (12) which is spaced apart from the container inlet (10) and via which the fermented substrate is discharged from the reactor interior (9), and

wherein in the reactor interior (9) a plurality of in reactor container

In the direction of longitudinal extent and thus separate stirring devices (19) spaced apart as seen in the plug flow direction, by means of which the substrate is locally circulated and / or by means of which the substrate is conveyed in plug flow flow direction (x), characterized in that the stirring devices (19 ) or at least one of the stirring devices (19) is designed as an exchangeable stirring device which, especially when the reactor vessel (2) is full and / or when the plug flow is operating,

Fermenter (1), can be removed from the reactor interior (9) and / or can be inserted into the reactor interior (9), preferably seen in the vertical axis direction from above from the reactor interior (9) and / or into the reactor -Interior (9) can be used.