Methods for using manure and biogas plants to carry out the process

Abstract

Methods for the use of manure (17) comprising the following steps: • Separating manure (17) into solid (23) and liquid (18) before the manure (17) is fed into a biogas reactor (2), • Feeding the separated liquid (18) into a biogas reactor (2), and • Use of the separated solid (23) as a wood substitute for the production of fiber molded parts, • wherein a digestate (20) from the biogas reactor (2) is at least partially mixed with the manure (17) to be separated.

Description

[0001] The invention relates to a method for using liquid manure and a corresponding biogas plant for carrying out the method.

[0002] The state of the art includes various biogas plants. These typically have at least one biogas reactor in which manure and / or plant substrate are gasified. The resulting gas can be used in various ways, for example, in a combined heat and power plant.

[0003] Furthermore, the state of the art recognizes various manufacturing methods for molded fiber parts. In particular, wood fibers are pressed together with a binding agent into molded parts, such as boards. These molded parts are known, for example, as MDF boards. The wood fibers can be fully or partially replaced by other plant fibers obtained from digestate from biogas production.

[0004] DE 10 2016 004 570 B3 shows board materials, composite materials and composite materials based on wood and / or separated manure, containing geometrically regular and / or irregular, free and / or aggregated and / or agglomerated carbon nanoparticles, carbon microparticles and / or carbon macroparticles.

[0005] US 2012 / 0 145 627 A1 discloses a method and apparatus for the anaerobic digestion of organic waste, preferably for producing a useful biogas. One or more separation stages downstream of the digester separate active bacteria and undigested organisms from the digestate and return the separated substances to the digester.

[0006] CN 105 746 363 A shows a recirculation system for organic pig farming. The recirculation system comprises a pig feeding area, a biogas digester area, an organic fertilizer processing area, and a forage grass planting area. The pig feeding area includes a pig excrement separation device. Liquid excrement obtained by the solid-liquid separation of the pig excrement separation device enters the biogas digester area through a wastewater treatment line. The liquid excrement undergoes anaerobic fermentation in the biogas digester area. Solid excrement obtained by the solid-liquid separation of the pig excrement separation device enters the organic fertilizer processing area to produce organic fertilizer.

[0007] DE 10 2005 055 310 A1 shows a device with a complex system of a cycle for the treatment and utilization of the fermentation residues from biogas plants for the use of surplus water and energy for the cultivation of fish cultures.

[0008] DE 198 13 738 C1 concerns a building material based on cellulose-containing, small-structure fibers from the separation of cattle manure.

[0009] CN 1 03 342 586 A relates to the technical field of humic acid from biogas sludge and its production, in particular to biogas residue sludge and its production processes.

[0010] The object of the invention is to provide a method for using liquid manure that enables the most efficient use of the raw materials. Further tasks may arise from the methods and systems described here, as well as their advantages.

[0011] The problem is solved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the invention. First aspect:

[0012] A first aspect shows a method for operating a biogas plant. The process involves separating manure into solids and liquids. Preferably, manure from non-ruminant mammals, such as pigs, is used. However, other manures, such as those from cattle or poultry, can also be used.

[0013] The separated solids are significantly drier than the separated liquids. Separation takes place before the manure is fed into a biogas reactor. Thus, at least some of the manure to be separated is manure that has not yet been used for gas production. The term "manure" refers to animal excrement, possibly with plant additives such as bedding. The manure is preferably separated in a press screw separator.

[0014] The separated liquid is fed to the biogas reactor and used in the biogas reactor to produce biogas. The biogas reactor is, in particular, at least one fermenter and / or at least one secondary fermenter. Preferably, plant substrate is fed to the biogas reactor in addition to the separated liquid. In particular, at least a portion of the separated liquid is mixed with the plant substrate outside the biogas reactor, and the mixture is fed to the biogas reactor.

[0015] According to the invention, the separated solid is used to produce molded fiber parts. The lignocellulose-containing fibers in the solid are particularly suitable for this purpose. Thus, the solid separated from liquid manure serves as a wood substitute. The molded fiber parts are, in particular, fiberboards, such as MDF boards. However, non-board-shaped molded fiber parts can also be produced from the separated solid. The solid can also be mixed with other fibers, such as wood fibers, to produce the molded fiber parts. Furthermore, fuel pellets are also among the molded fiber parts, which can be produced entirely or partially from the separated solid.

[0016] Within the scope of the invention, it was recognized that the relatively large fibers in the separated solid are significantly better suited for the production of fiber molded parts if they do not pass through the biogas reactor and are damaged by the fermentation processes. During the separation of the manure, easily usable ingredients and the short fiber portions remain in the separated liquid and are available in the biogas reactor for biogas production. It was recognized that the separated solid with the relatively long fibers plays a subordinate role in the fermentation process, as these fibers are difficult to utilize in the biogas reactor. Nitrogen inhibition in the biogas reactor reduces the anaerobic process, so that often more than 50% of the dry matter, primarily the large fibers, remains in the digestate.Therefore, according to the invention, these large fibers are removed from the liquid manure before the fermentation process and can be used for the production of the fiber molded parts, bypassing the fermentation process.

[0017] Any required amount of lignocellulose-containing material in the biogas reactor can easily be achieved by adding the plant substrate.

[0018] Furthermore, it is preferred to mix at least part of the digestate with the manure to be separated. This portion of the digestate then undergoes the separation process step together with the fresh manure.

[0019] In particular, it is planned to feed at least part of the digestate to a fine filter. The fine filter filters out smaller fibers, in particular, than during separation. The filter concentrate produced in the fine filter is mixed with the manure to be separated, as described above. The clear effluent from the fine filter is preferably fed to a final storage facility of the biogas plant; it can pass through a secondary digester before the final storage facility, or it can be used for other purposes.

[0020] The fine filter is, in particular, a pressure filter in which the digestate is vibrated by a vibration drive, thereby pushing or moving it through a corresponding sieve. Patent DE 100 47 431 B4 shows a pressure filter with a vibration drive, which can preferably be used as a fine filter for the described process.

[0021] Preferably, a slurry collection tank is used, from which the slurry is conveyed via a supply line into the inlet of a separator. The outlet of the fine filter for the filter concentrate is preferably connected to both the slurry tank and the supply line or inlet. This allows the filter concentrate to be mixed with the slurry in the slurry collection tank or directly introduced into the slurry flowing into the separator. This makes it possible to regulate the moisture content of the slurry to be separated.

[0022] Preferably, a fine filter mesh size with the following specification is used in the fine filter: The mesh size is, in particular, the hole diameter of a fabric sieve stabilized by a support cage, or the gap width of a bar sieve. Preferably, the bar sieve is used in the fine filter, in particular designed as a pressure filter with a vibration drive. The upper limit of the mesh size used is preferably at most 0.3 mm, in particular at most 0.2 mm, particularly preferably at most 0.1 mm. The lower limit of the mesh size used is preferably at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.07 mm.

[0023] Preferably, a separation gap width with the following specification is used for separation, particularly in the press screw separator: A bar screen is preferably used for separation. The gap width for separation is preferably larger than the gap width or mesh size in the fine filter. The upper limit of the separation gap width used is preferably at most 1 mm, in particular at most 0.8 mm, particularly preferably at most 0.6 mm. The lower limit is preferably at least 0.1 mm, preferably at least 0.3 mm, particularly preferably at least 0.4 mm.

[0024] As already described, the separated solid is used at least in part to produce the molded fiber parts. In particular, it is intended that the separated solid be processed prior to the production of the molded fiber parts. During this processing, the solid is, in particular, dried and / or cleaned and / or sorted.

[0025] The process preferably comprises the step of producing the molded fiber parts. The separated solid, particularly in processed form, is pressed together with a binder to form the molded fiber part. The solid obtained from manure can be mixed with other fibers. Second aspect:

[0026] A second aspect comprises a method for operating a biogas plant comprising the following steps: First, the liquid manure and / or plant substrate are fed into the biogas reactor. The digestate from the biogas reactor is at least partially fed to the fine filter described above. The filter concentrate produced in the fine filter is at least partially fed back into the same biogas reactor as substrate. Thus, the fine filter downstream of the biogas reactor and the return of the filter concentrate can be used independently of the use of the large fibers as a wood substitute.

[0027] Preferably, the manure is separated before being fed into the biogas reactor, as described above. The filter concentrate is preferably mixed at least partially with the manure to be separated. The separated liquid is fed to the biogas reactor. The separated solids can also be partially fed to the biogas reactor or used for other purposes. The previously described separation gap width is preferably used for separation.

[0028] As already described, the fine filter is primarily a pressure filter in which the digestate is vibrated by a vibration drive, thereby pushing or moving it through a corresponding sieve. Preferably, the fine filter uses the previously described fine filter gap or mesh size.

[0029] Preferably, a slurry collection tank is used, from which the slurry is conveyed via a supply line into the inlet of a separator. The outlet of the fine filter for the filter concentrate is preferably connected to both the slurry tank and the supply line or inlet. This allows the filter concentrate to be mixed with the slurry in the slurry collection tank or to be introduced directly into the slurry flowing into the separator.

[0030] The invention preferably comprises a biogas plant designed to carry out one of the methods according to the first aspect or the second aspect. The biogas plant preferably comprises a press screw separator for separating the liquid manure and the described fine filter. Furthermore, the biogas plant preferably comprises at least one biogas reactor and the corresponding devices for moving the media. Third, inventive aspect:

[0031] According to a third aspect, the invention comprises a method for utilizing liquid manure, comprising the following steps: first, the manure is separated into solids and liquids without first being fed into a biogas reactor. As a result, the relatively large fibers contained in the manure are not damaged by the fermentation process. As described in the first aspect of the present invention, the separated solids are used, at least in part, as a wood substitute for the production of molded fiber parts.

[0032] In the third aspect, the separated liquid is used in a biogas reactor as described.

[0033] A digestate from the biogas reactor is at least partially mixed into the manure to be separated.

[0034] The separation of the manure is preferably carried out with the described separation gap width and in a press screw separator.

[0035] The features described in the context of the first aspect for producing the fiber molded parts and / or for processing the fibers from the separated solid find correspondingly advantageous applications in the context of the third aspect.

[0036] Further details, advantages, and features of the present invention will become apparent from the following description of an embodiment with reference to the drawing. It shows: Fig. 1 a biogas plant according to the invention for carrying out the process according to the invention.

[0037] Fig. 1 shows a biogas plant 1 and a stable system 7. Slurry 17 flows from the stable system 7 into a slurry collection tank 8 of the biogas plant 1.

[0038] The biogas plant 1 comprises a biogas reactor 2, in particular designed as a fermenter, and a downstream repository 3. Furthermore, the biogas plant 1 comprises a solids silo 4 for plant substrate 19. The plant substrate 19 can be conveyed into the biogas reactor 2 via a mixer 5 and a conveyor 6.

[0039] In the example shown, the biogas produced in biogas reactor 2 and the repository 3 is used in a combined heat and power plant 13. The waste heat from the combined heat and power plant 13 is used to heat the biomass in biogas reactor 2 via a heating system 14.

[0040] The biogas plant 1 comprises a separator 9, in particular designed as a press screw separator. The manure 17 is conveyed from the manure collection tank 8 via a feed line 91 into an inlet 92 of the separator 9. In the separator 9, the manure 17 is separated into a separated liquid 18 and solid 23.

[0041] The separated liquid 18 can be fed either directly to the biogas reactor 2 or to the mixer 5.

[0042] The digestate 20 from the biogas reactor 2 is fed to a fine filter 10. The clear effluent 22 from the fine filter 10 is fed to the final storage facility 3. The filter concentrate 21 from the fine filter 10 can be fed either into the slurry collection tank 8 or directly into the supply line 91 or the inlet 92.

[0043] In particular, the previously described gap width is used in the separator 9. The fine filter 10, as already described, is preferably designed as a pressure filter with a vibration drive. The described gap or mesh width is preferably used in the fine filter 10.

[0044] To pump the media, the biogas plant 1 comprises pumps 16; in the example shown, these are located in the slurry collection tank 8 and between the biogas reactor 2 and the fine filter 10. Furthermore, several agitators 15 are provided; for example, in the slurry collection tank 8, in the biogas reactor 2, and in the final storage facility 3.

[0045] The solid 23 from the separator 9 is cleaned and / or dried and / or sorted in a processing plant 11. This produces fibers from the solid 23, which are then pressed into fiber moldings in a fiber molding plant 12, optionally with the addition of additional fibers, together with a binder.

[0046] With the separator 9 shown, the processing plant 11 and the fiber molding plant 12, corresponding fibers can be separated from the liquid manure and used to produce fiber moldings, independently of the production of biogas.

[0047] Furthermore, with the system shown it is also possible, regardless of the use of the solid 23, to filter the digestate 20 in the fine filter 10 and to feed the filter concentrate 21 back to the biogas reactor 2, in particular via the separator 9.

[0048] In addition to the above written description of the invention, for its supplementary disclosure, reference is hereby explicitly made to the graphic representation of the invention in Fig. 1 referred to. List of reference symbols 1 biogas plant 2 Biogas reactor, especially fermenter 3 repositories 4 solids silo 5 mixers 6 sponsors 7 stables 8 slurry collection containers 9 Separator, especially press screw separator 91 supply line 92 inlet 10 fine filters 11 Treatment plant 12 Fiber molding plant 13 combined heat and power plants 14 Heating 15 agitator 16 Pump 17 Manure 18 separated liquid 19 plant substrate 20 digestate 21 Filter concentrate 22 Clear flow 23 Solid with fibers

Claims

[1] Method for the use of liquid manure (17) comprising the following steps: • Separating manure (17) into solids (23) and liquids (18) before the manure (17) is fed into a biogas reactor (2), • Feeding the separated liquid (18) into a biogas reactor (2), and • Using the separated solid (23) as a wood substitute for the production of fiber molded parts, • wherein a digestate (20) from the biogas reactor (2) is at least partially mixed into the liquid manure (17) to be separated. [2] Method according to claim 1, wherein the digestate (20) from the biogas reactor (2) is fed to a fine filter (10), wherein the filter concentrate (21) produced in the fine filter (10) is fed to the liquid manure (17) to be separated. [3] Method according to claim 2, wherein a liquid manure collection tank (8) is used, from which the liquid manure (17) is conveyed via a feed line into an inlet of a separator (9), wherein the filter concentrate (21) can be fed optionally to the liquid manure collection tank (8) or directly into the feed line (91) or the inlet (92). [4] Method according to one of claims 2 or 3, wherein in the fine filter (10) a fine filter gap or mesh width, in particular as the gap width of a bar screen, is used, of • at most 0.3 mm, preferably at most 0.2 mm, particularly preferably at most 0.1 mm and / or • at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.07 mm. [5] Method according to one of the preceding claims, wherein a gap width of a bar screen is used for separation, of • at most 1 mm, preferably at most 0.8 mm, particularly preferably at most 0.6 mm and / or • at least 0.1, preferably at least 0.3 mm, particularly preferably at least 0.4 mm. [6] Method according to one of the preceding claims, wherein the separated solid (23) is processed before the production of the fiber molded parts, preferably by drying and / or cleaning and / or sorting. [7] Method according to one of the preceding claims, comprising the step of producing the fiber molded parts, wherein the separated solid (23) is pressed together with a binder to form the fiber molded part. [8] Method according to one of the preceding claims, wherein in addition to the liquid manure (17) plant substrate (19) is fed to the biogas reactor (2). [9] Biogas plant (1) designed to carry out one of the methods according to one of the preceding claims.

Images