Device for crushing substrate

Abstract

Device (1) for comminuting substrate, in particular for fine comminuting of liquid biogas substrate, comprising a hollow-shaped mixing container (100) and a comminuting device (20) arranged inside therein, wherein the comminution device (20) comprises a shaft (21) rotatable about a rotary axis, which can be driven by a drive motor (16) and on which at least one comminution element (22) is mounted, the comminution device (22) is designed as an impact hammer (26) with at least one wing (27) extending radially towards the axis of rotation (L) and the wing (27) has at least one striking surface for comminuting the substrate, the device (1) has a housing cover (11), the mixing vessel (100) is designed in two parts with a lower housing vessel (5) with a flange (7) and an upper housing vessel (8) with a flange (9), the flanges (7, 9) being connected to each other by means of a flange connection, the upper housing vessel (8) being closable with the housing cover (11), the drive motor (16) and the shaft (21) are mounted on the housing cover (11) and the lower housing container (5) is provided with an inlet pipe connection (12) for the inlet of the supplied substrate and the upper housing container (8) is provided with a return pipe connection (15) for the outlet of the crushed substrate.

Description

[0001] The invention relates to a device for comminuting substrate, in particular for fine comminuting liquid biogas substrate, comprising a hollow mixing container and a comminution device arranged inside it, wherein the comminution device comprises a shaft which is rotatable about an axis of rotation, which is drivable by a drive motor and on which at least one comminution element is mounted.

[0002] Fermentation and biogas plants produce biogas from the fermentation of biomass. The raw material used to produce biogas is usually referred to as a substrate or feedstock. Theoretically, any type of biomass that can be broken down under anaerobic conditions (fermentation) is suitable. Depending on the chemical composition (carbohydrates, fats, proteins) of the biomass, different amounts of biogas with different methane contents are produced.

[0003] A distinguishing feature of biogas plants is their operation as wet or dry fermentation or digestion. In wet fermentation, the high water content in the fermentation substrate makes the mass stirrable and fluid, and it is thoroughly mixed during fermentation. Dry fermentation, or solid-state digestion, is carried out using stackable organic biomass. In contrast to wet fermentation, the digestate is neither liquefied nor is there constant mixing during fermentation. The choice of process depends primarily on the substrates.

[0004] However, structurally rich biomass often blocks the agitators in the fermentation tank required for wet fermentation. For wet fermentation, the solid biomass must be well crushed and kept pumpable with liquid. This is important because the solid components often combine, making it difficult to pump. Furthermore, a liquid layer forms on top of the tank, which then requires laborious removal. Furthermore, the pumps have to work harder with viscous material, which in turn leads to faster wear and higher energy consumption.

[0005] To reduce the solids in an aqueous substrate before filling it into the fermentation vessel, comminution devices are provided, which are preferably integrated into the existing feed line used to transport the viscous material into the vessel. In the usually hollow-cylindrical comminution device, the substrate is reduced by an internally arranged comminution device, such as a blade system. This reduces the size of the solids and plant fibers and makes the aqueous substrate more fluid. This makes the substrate easier to transport and reduces the risk of a liquid layer forming on top in the fermentation vessel, as improved mixing and thus homogenization of the substrate is achieved.In addition, the shredding process increases the surface area of ​​the solids, which has a positive effect on biogas formation because more gas-forming bacteria can now bond with the surface.

[0006] However, the device is subject to high stress and therefore significant wear. In particular, the shredding device can be damaged by foreign objects in the substrate, such as stones. The shredding device is therefore a wear part that often needs to be replaced after just a few days of use, which is both complex to maintain and costly. Furthermore, it is desirable to further increase the degree of shredding of the substrate and utilize cavitation effects for the treatment of persistent organic substances.

[0007] DE 196 35 500 A1 describes a device for the high-energy and / or ultra-fine grinding of solids, comprising a grinding container designed as a grinding chamber with a closed housing, which accommodates a charge of pourable grinding media and, to induce intensive grinding media movement, a rotor equipped with agitator elements that can be driven to rotate about a horizontal axis. The rotor shaft is hermetically sealed from the housing, which is stationary during the grinding process, by at least one shaft seal, wherein the container has a closable passage provided alternately as a filling or discharge opening. The improvement of the grinding device consists in the container having an inlet nozzle and a separate, spatially separated outlet nozzle for the material to be ground, and in that these are arranged tangentially relative to the outer rotational circle of the rotor.

[0008] From DE 20 2012 104 378 U1 a housing wall for a device for comminuting substrate, in particular for fine comminuting biogas substrate, is known, wherein the housing wall is of hollow cylindrical design and, in the comminution operating state of the device, radially surrounds comminution elements of the device which are arranged radially projecting from a shaft which can be arranged rotatably about the longitudinal axis of the housing wall, characterized in that on the inner side of the housing wall facing the comminution elements, at least in the region of the longitudinal extent of the housing wall in which the comminution elements are arranged in the comminution operating state, at least one helically designed guide profile is arranged.

[0009] DE 10 2011 089 615 A1 describes a comminution device having a comminution chamber with a bottom wall and a peripheral wall projecting upwards from the bottom wall, a drive shaft extending substantially orthogonally to the bottom wall and rotatably drivable about a rotation axis, and at least one comminution element arranged in the comminution chamber, wherein the comminution element is pivotally mounted with respect to the drive shaft exclusively in a plane extending orthogonally to the rotation axis, and wherein the radially outer end of the comminution element facing the peripheral wall has a radially outer surface extending at least partially parallel to the peripheral wall and / or the side of the comminution element leading upon rotation of the drive shaft is flattened.

[0010] DE 10 2017 102 281 A1 describes an impact reactor for comminuting composite material, comprising a cylindrical shell and a base which enclose an impact reactor chamber, wherein a rotor is provided in the impact reactor chamber and at least one filling opening for filling the composite material and a removal opening for discharging the comminuted composite material, wherein at least one gap is arranged between the cylindrical shell and the base.

[0011] From DE 830 604 B an impact mill is known, in particular for milling wheat and other grains, with a centrifugal wheel rotating around a vertical axis, which centrifugal wheel throws the material particles to be ground at high speed in a direction containing a radial and a tangential component against a plurality of impact surfaces, on which the particles are crushed by the impact effect of the impact, and which intersect the horizontal plane in a direction with a radial component, and which are simultaneously inclined to the vertical in such a way that the fragments rebounding against them acquire a downward movement component, wherein the horizontal angle between the plane of each impact surface and the movement direction of the impacting material particles to be crushed is greater than 90°, so that the velocity vector of the rebounding fragments is not only downward,but also in relation to the centrifugal wheel is directed more upwards than the velocity vector of the impacting material particles to be crushed.

[0012] DE 20 2005 021 946 U1 describes a device for comminuting heaped material, comprising a housing held by a frame with a vertical axis, which housing has at least one inlet opening for the heaped material at the upper end and an outlet at the lower end, a drive shaft arranged vertically centrally in the housing, which drive shaft is driven by a drive motor, and a rotor attached to the drive shaft with a plurality of rotor elements arranged offset in the circumferential direction and / or at an axial distance, which rotor elements extend, at least when the rotor rotates, close to the housing wall in order to process the falling heaped material, characterized in that the housing has two housing sections arranged vertically one above the other, of which the lower one has a larger diameter, at least in the upper area adjacent to the area above it, than the adjacent area of ​​the upper housing section.It is the object of the invention to provide a device for comminuting substrates which enables reliable and efficient comminution of solids in aqueous substrates and in which the material wear of the components of the comminution device is low.

[0013] This problem is solved by the subject matter of patent claim 1. Preferred developments can be found in the subclaims.

[0014] The invention relates to a device for comminuting substrate, in particular for fine comminution of liquid biogas substrate, comprising a hollow mixing container and a comminution device arranged on the inside therein, wherein the comminution device comprises a shaft which is rotatable about an axis of rotation, which can be driven by a drive motor and on which at least one comminution element is mounted, characterized in that the comminution element is designed as an impact hammer with at least one wing extending in the radial direction relative to the axis of rotation and the wing has at least one impact surface for comminuting the substrate.

[0015] It is therefore a key aspect of the invention that the comminution of the substrate is based on the principle of a hammer mill or impact mill, rather than on cutting the substrate. The comminution of the substrate is therefore essentially achieved through kinetic impact and impact comminution. Upon entering the impact circle of the impact hammer, the substrate strikes the impact surface of the rotating blade. The disruption of the substrate is essentially based on the impact of the impact surface on the substrate.

[0016] According to a preferred development of the invention, it is provided that the normal vectors at all points of the striking surface enclose an angle with the axis of rotation which is greater than 75°, more preferably greater than 85° and most preferably 90°.

[0017] Preferably, the wing has a thickness and the striking surface thus a width in the range of 5 to 15 mm, more preferably in the range of 8 to 12 mm and most preferably of 10 mm.

[0018] According to a preferred embodiment of the invention, the impact hammer is disk-shaped with two symmetrically arranged blades, each blade having a side surface that forms a striking surface. Preferably, the impact hammer has a circular disk in its interior, with the two blades adjoining its peripheral side.

[0019] Advantageously, the impact hammer is connected to a bearing that is non-rotatably connected to the shaft.

[0020] In a further embodiment, it is provided that a flow ring is arranged in the mixing container in the plane of rotation of the impact hammer.

[0021] In particular, the flow ring is provided with teeth that protrude into the interior of the mixing container.

[0022] According to the invention, the mixing container is constructed in two parts, comprising a lower housing container with a flange and an upper housing container with a flange, the flanges being connected to each other by means of a flange connection. The upper housing container can be closed with a housing cover, on which the drive motor and the shaft are mounted.

[0023] Advantageously, the flow ring is arranged between the two flanges and the distance between the orbiting surfaces of the impact hammer blades and the teeth of the flow ring is in the range of 1-2 mm.

[0024] According to the invention, it is also provided that the lower housing container is provided with an inlet pipe socket for the inlet of the supplied substrate and the upper housing container is provided with a return pipe socket for the outlet of the shredded substrate.

[0025] Advantageously, the lower housing container and the upper housing container are each provided with flow breakers.

[0026] In a further embodiment, the flow breakers are designed as webs which are arranged on the inside of the housing of the mixing container parallel to the axis of rotation and protrude into the interior of the mixing container.

[0027] Preferably, the device is operated so that the rotation speed of the impact hammer is in the range of 50-70 m / sec.

[0028] Advantageously, a lifting device is provided for lifting the housing cover with the shredding device arranged thereon.

[0029] The present invention thus ensures that the solids in the liquid substrate have the required degree of comminution. This enables the ultrafine comminution of liquid substrate / biomass for use in biogas plants. The substrate is fed into the mixing tank through the inlet nozzle and finely comminuted in the mixing tank by means of the rotating impact hammer. The impact hammer comminution in the mixing tank comminutes the fed substrate by rotation. The wing-shaped impact hammer is highly resistant to foreign bodies. It can lead to very good comminution results because the impact surfaces, with a speed of 50-70 m / sec, have the necessary penetrating comminution effect.

[0030] This velocity of 50-70 m / sec causes cavitation effects as the substrate enters the upper housing container, meaning that vapor bubbles form in the rapidly flowing substrate. This allows even persistent organic matter to be broken down, making it available for biogas production. This can reduce the material requirements for a biogas plant, as the input material can be used more efficiently. Furthermore, the fine grinding of the solids in the liquid substrate prevents the formation of a liquid layer in the fermentation vessel.

[0031] During the comminution process, the impact surfaces of the two blades rotate along the teeth of the flow disc at a rotational speed of 50-70 m / sec. The substrate can therefore only be conveyed further if it can pass through the gap between the teeth and the impact surface of the blades. Furthermore, the flow ring slows down the liquid substrate before it reaches the impact hammer, increasing the interaction time between the liquid substrate and the impact surfaces of the impact hammer, thereby increasing the comminution effect. Furthermore, the teeth of the flow ring act as a counter-blade, which increases comminution efficiency, particularly with fibrous substrates such as grass. The present invention thus ensures that all of the substrate fed into the mixing container is comminuted by the impact surfaces of the impact hammer.

[0032] The invention is explained in more detail below using a preferred embodiment with reference to the drawings.

[0033] The drawings show: Fig. 1 a side view of an embodiment of the device according to the invention for comminuting substrate; Fig. 2 a cross-sectional view of the Fig. 1 illustrated device; Fig. 3 a perspective top view of the mixing container of the device according to the invention; Fig. 4 a perspective upper view of the comminution member of the device according to the invention; Fig. 5 a cross-sectional view of the shredding device from Fig. 4; Fig. 6 a side view of the shredding device; Fig. 7 a perspective top view of the comminution device mounted on the mixing container lid; Fig. 8 a perspective bottom view of the comminution device mounted on the mixing container lid.

[0034] In the Fig. Figure 1 shows a schematic perspective view of an embodiment of the device 1 according to the invention for comminuting liquid substrates. The device 1 comprises a support plate 2 for setting up the device 1 at a desired location. An annular fastening element 3 is attached to the support plate 2. The fastening element is provided with a flange 4 designed for connection to a lower hollow housing container 5.

[0035] The housing container 5 has a first flange 6, which is connected to the flange 4 during assembly of the device 1. A second flange 7 is also provided, which is designed for connection to an upper hollow housing container 8. The outer wall of the housing containers 5 and 8 can each be cylindrical. However, it is also conceivable for the shape to be truncated conical or provided with curves.

[0036] The second housing container 8 also has a lower first flange 9, which is connected to the second flange 7 of the lower housing container 5 during assembly of the device 1. A second flange 10 is also provided, which is connected to a housing cover 11 during assembly. Hexagon screws are preferably provided for the fluid-tight connection of the flanges 4, 6 and 7, 9, as well as the flange 10 to the housing cover 11.

[0037] The lower housing container 5 is provided with a flanged pipe socket 12, which serves as the inlet for the liquid substrate or biomass. A lateral sampling port 13 is arranged on the pipe of the pipe socket 12 to allow samples of the supplied substrate to be taken during operation of the device 1. A further pipe socket 14 is provided to remove foreign matter from the supplied substrate. The upper housing container 8 is provided with a pipe socket 15 for the return flow of the comminuted substrate.

[0038] A drive motor 16 and a power supply 17 are mounted on the mixing container lid 11. The drive motor 16 is also mounted on a base frame 18, on which a lifting device 19 is arranged. This allows the drive motor 16, together with the mixing container lid 11, to be lifted to the upper housing container 11 after loosening the flange connection. The lifting device 19 is preferably equipped with a cable winch. However, other embodiments of the lifting device 19 can also be provided.

[0039] Fig. Figure 2 shows the internal structure of the device 1 according to the invention. The device 1 contains the comminution device 20, which is mounted for rotation about a rotation axis L. The comminution device 20 comprises a rotatable shaft 21, which is connected via a coupling to the drive shaft of the drive motor 16 and is driven by the latter. A comminution element 22 is arranged at the lower end of the shaft 21 and extends radially relative to the rotation axis L of the shaft 21.

[0040] In the assembled state of the device 1, the comminution element 22 is located in the plane between the two flanges 7 and 9. A flow disk 23 with teeth 24 projecting into the interior of the housing containers 5 and 8 is also arranged between the flanges 7 and 9. Furthermore, baffles 25 aligned vertically in the direction of the rotation axis L are arranged in both the lower housing container 5 and the upper housing container 8. The liquid, preferably aqueous, substrate is fed in via the pipe socket 12 and conveyed upward into the upper housing container 8 by the negative pressure generated by a pump (not shown here). The substrate and the solids it contains pass through the comminution element and are comminuted. The comminuted substrate then leaves the upper housing container 8 via the return pipe socket 15.

[0041] In Fig. Figure 3 shows a detailed view of the interior of the mixing tank 100, which consists of the upper housing tank 8 and the lower housing tank 5. The flow ring 23 with the teeth 24 projecting into the interior of the mixing tank 100 is arranged between the flanges 7 and 9. The teeth 24 can have pointed edges or be rounded. They can be uniformly formed or differ from one another in their structure. In the exemplary embodiment shown here, four flow breakers 25 are arranged in each of the lower housing tank 5 and the upper housing tank 8, each aligned vertically in the direction of the rotation axis L.

[0042] However, it is also conceivable to increase the number of baffles 25. The baffles 25 are preferably designed as webs projecting into the interior of the mixing container 100, with the baffles 25 in the lower housing container 5 and the baffles 25 in the upper housing container 8 being arranged one above the other. However, they can also be arranged offset from one another. The comminution element 22 is arranged in the plane spanned by the flow disk 23.

[0043] In the Fig.Figures 4 to 8 show the comminution device 22 in detail. The comminution device 22 is designed as a rotating impact hammer and consists of a disk-shaped impact hammer 26 with two symmetrically designed blades 27, which can be attached to the shaft 21 by means of a bearing 28. However, it is also conceivable to design the two blades 27 differently or to design the impact hammer 26 with only one blade 27 or with more than two blades 27. The side surfaces 29 of the blades 27 are conical and their circumferential surface 30 is circular. The side surface 29 of the impact hammer 26 forms the impact surfaces for comminuting the substrate. During the comminution process, the side surfaces 29 of the two blades 27 rotate along the teeth 24 of the flow disk 23 at a rotational speed of 50-70 m / sec.The substrate can thus only be conveyed further if it can pass through the gap between the teeth 24 and the side surface 29 of the vanes 27. In addition, the flow ring 23 slows down the liquid substrate in front of the impact hammer 26, so that the interaction time between the liquid substrate and the impact surfaces of the impact hammer 26 is increased, thereby increasing the crushing effect.

[0044] The baffles 25 further decelerate the substrate by engaging the substrate flow. Furthermore, the teeth 24 of the flow ring 23 act as a counter-blade. This ensures that the entire substrate fed into the mixing container 100 is captured and crushed by the impact surfaces of the impact hammer 26.

[0045] The present invention thus ensures that the solids in the liquid substrate have the required degree of comminution. This enables the ultrafine comminution of liquid substrate / biomass for use in biogas plants. The substrate is fed into the mixing tank 100 through the inlet nozzle 12 and finely comminuted in the mixing tank 100 by means of the rotating impact hammer 22. The impact hammer 22 comminutions the supplied substrate in the mixing tank 100 by rotation. The wing-shaped impact hammer 26 is highly resistant to foreign matter.

[0046] It produces very good comminution results because the impact surfaces, at a speed of 50-70 m / sec, provide the necessary penetrating comminution effect. This speed of 50-70 m / sec creates 8 cavitation effects when the substrate enters the upper housing container, i.e. vapor bubbles are formed in the fast-flowing substrate. This breaks down persistent organic substances so that they are then available for biogas production. This reduces the material required for a biogas plant because the material used can be used more efficiently. In addition, the fine comminution of the solids in the liquid substrate prevents the formation of a liquid layer in the fermentation tank of the biogas plant.

[0047] Furthermore, the impact hammer 26 is subject to less wear due to its aerodynamic design. A service life in the range of 2 to 5 months is achieved, depending on the substrate used and the operating time of the device 1 according to the invention. Since the impact hammer 26 is attached to the bearing 28 with only a few screws, the working time for replacing the impact hammer 26 is approximately 15-20 minutes. The impact hammer 26 is preferably made of steel, and the thickness of the steel plate is in the range of 10 mm. Due to the high rotational speed of the impact hammer mechanism 22, it can be assumed that with a substrate throughput of 20 t per hour, the substrate to be crushed will collide with the impact surface 30 of the impact hammer 26 approximately 20 times.

[0048] Since the impact hammer 26 is preferably designed symmetrically and is thus flow-neutral, the direction of rotation can be changed in either direction. Therefore, the direction of rotation can be adjusted either clockwise or counterclockwise.

[0049] In addition, the impact hammer rotating mechanism 22 can be operated at different speeds depending on the type and quality of the substrate fed in.

[0050] Since the bearing 28 and the impact hammer 26 can develop high temperatures during operation, a cooling unit (not shown here) is provided. This unit is started when the device 1 begins operating and continues to operate even after the device 1 is switched off until the desired non-operating temperature is reached. The cooling unit safely dissipates the generated heat and prevents overheating of the bearing 28 and the shaft 21. A special oil is preferably used as the cooling medium, since water is not suitable as a cooling medium due to the briefly occurring high temperatures, which can reach over 100°C.

[0051] Furthermore, it is possible to integrate the device 1 according to the invention into the automatic control device of a biogas plant, so that the device 1 can be operated via the control device of the biogas plant. List of reference symbols 1 device for crushing substrate 2 carrier plate 3 Fastening element 4 Flange 5 lower housing container 6 first flange 7 second flange 8 upper housing container 9 first flange 10 second flange 11 Housing cover 12 inlet pipe sockets 13 sampling nozzles 14 foreign body pipe sockets 15 return pipe sockets 16 Drive motor 17 Power supply 18 Base frame 19 Lifting device 20 Shredding device 21 Wave 22 Crushing organ 23 Flow disc 24 teeth 25 baffles 26 impact hammer 27 wings 28 warehouses 29 Side surfaces / faces 20 circulation areas 100 mixing containers

Claims

[1] Device (1) for comminuting substrate, in particular for fine comminuting liquid biogas substrate, comprising a hollow mixing container (100) and a comminuting device (20) arranged inside it, wherein the comminution device (20) comprises a shaft (21) which is rotatable about an axis of rotation and which can be driven by a drive motor (16) and on which at least one comminution element (22) is mounted, the comminution member (22) is designed as an impact hammer (26) with at least one wing (27) extending in the radial direction relative to the axis of rotation (L), and the wing (27) has at least one impact surface for comminuting the substrate, the device (1) has a housing cover (11), the mixing container (100) is designed in two parts with a lower housing container (5) with a flange (7) and an upper housing container (8) with a flange (9), which flanges (7, 9) are connected to one another by means of a flange connection, the upper housing container (8) can be closed with the housing cover (11), the drive motor (16) and the shaft (21) are mounted on the housing cover (11) and the lower housing container (5) is provided with an inlet pipe socket (12) for the inlet of the supplied substrate and the upper housing container (8) is provided with a return pipe socket (15) for the outlet of the shredded substrate. [2] Device (1) according to claim 1, wherein the impact hammer (26) is disc-shaped with two symmetrically arranged wings (27), wherein the wings (27) each have a side surface (29) which each form an impact surface. [3] Device (1) according to claim 2, wherein the impact hammer (26) is connected to a bearing (28) which is connected to the shaft (21) in a rotationally fixed manner. [4] Device (1) according to one of the preceding claims, wherein a flow ring (23) is arranged in the mixing container (100) in the plane of rotation of the impact hammer (26). [5] Device (1) according to claim 4, wherein the flow ring (23) is provided with teeth (24) which project into the interior of the mixing container (100). [6] Device (1) according to claim 5, wherein the flow ring (23) is arranged between the two flanges (7, 9) and the distance between the circumferential surfaces (30) of the wings (27) of the impact hammer (26) and the teeth (24) of the flow ring (23) is in the range of 1-2 mm. [7] Device according to one of claims 1 to 6, wherein the lower housing container (5) and the upper housing container (8) are each provided with flow breakers (25). [8] Device according to claim 7, wherein the flow breakers (25) are designed as webs which are arranged on the inside of the housing of the mixing container (100) parallel to the axis of rotation (L) and project into the interior of the mixing container (100). [9] Device (1) according to one of the preceding claims, wherein a lifting device (19) is provided for lifting the housing cover (11) with the comminution device arranged thereon. [10] Use of a device (1) according to one of the preceding claims, wherein the rotational speed of the impact hammer (26) is in the range of 50-70 m / sec.

Images