CN111936612A

CN111936612A - Reactor and apparatus for anaerobic digestion

Info

Publication number: CN111936612A
Application number: CN201980024285.3A
Authority: CN
Inventors: 安蒂·约翰内斯·梅尔里宁
Original assignee: DORANOVA Oy
Current assignee: DORANOVA Oy
Priority date: 2018-03-01
Filing date: 2019-03-01
Publication date: 2020-11-13
Also published as: FI20185197A1; WO2019166620A1; FI128217B; EP3759210A1

Abstract

A continuous stirred reactor (100) for anaerobic digestion of biodegradable organic substrates is provided, the reactor comprising a horizontally extending reactor tank (101) having an inflow port at an entry end and at least one outflow port at a discharge end opposite the entry end. The reactor (100) further comprises means for continuous stirring of the organic substrate inside the reactor tank (101) and a temperature regulation system, advantageously comprising a plurality of internal tubes configured to traverse through the lateral walls and/or the base of the reactor tank and to convey a temperature regulation fluid along the internal tubes.

Description

Reactor and apparatus for anaerobic digestion

Technical Field

The present invention generally relates to systems and methods for anaerobic biodegradation of organic substrates with biogas recovery. In particular, the present invention relates to a continuously stirred horizontal reactor for dry anaerobic digestion of organic substrates, and to a plant installation comprising said reactor (or reactors).

Background

Anaerobic Digestion (AD) is a complex process of decomposing organic matter by methanogens that has been reduced in use in various biorefinery technologies including agricultural and industrial waste treatment. In all cases, anaerobic digestion is also accompanied by the production of biogas, which is further upgraded to produce biofuels.

Two types of anaerobic digestion processes, referred to as "wet" (DM of 5 to 15 wt%) and "dry" (DM of 30 to 55 wt%), respectively, are usually distinguished in order to manage solid waste having different Dry Matter (DM) contents. With an average capacity of 2m³To 4000m³Has an average capacity of 950m³To 1000m³Can be upgraded to about 2000m³The dry digester of (a) is generally more compact. Generally, any anaerobic digester can be used for both wet and dry processes; however, in practice, the equipment is designed to meet specific requirements imposed by the selection and/or availability of feed materials, expected output, available locations, and the like. Other advantages of dry digestion when used for waste treatmentTo relatively impure waste, i.e. containing large amounts of non-biodegradable matter; thus, the costs of pre-treating and conditioning the feedstock prior to digestion can be minimized.

A conventional AD plant comprises a pre-treatment facility, one or more digester reactors and several post-treatment facilities, the post-treatment facilities comprising a solids separator and a sanitary tank for digested material, and a recirculation means to return a portion of the digested material as inoculum into the reaction space. A common reactor configuration includes a fixed dome-shaped tank with one or more wall-bonded mixers in most cases. Dry AD reactors operating on a continuous flow-through basis are generally referred to as plug flow reactors and are implemented as horizontally extending narrow tanks with an inlet and an outlet in which the feed is constantly decomposed while travelling along the length of the tank. Some plug flow solutions are supplemented with a mixer or mixing screw in the form of a bladed rod.

Dry anaerobic digestion, also known as dry fermentation, gains further advantages for the following reasons. First, the disposal of the waste portion becomes more challenging. Some waste management measures prohibit the landfill of organic waste; thus, the waste fraction intended for recycling becomes drier and more difficult to pulverize due to the presence of a large amount of impurities such as stones, sand and dirt. Incineration of organic waste is a popular solution, but it provides lower energy yields and results in severe flue gas emissions. On the other hand, while dry matter can be treated to some extent by wet anaerobic digestion methods, wet anaerobic digestion methods do not allow for the presence of large amounts of impurities in the feedstock.

However, dry anaerobic digester solutions operating on a continuous flow basis suffer from several common drawbacks. In most cases, biodegradable waste obtained from agricultural and municipal sources contains substantial amounts of non-digestible solids such as stones, sand, glass and various plastics, which result in floating layers and large amounts of sediment in the digester. For handling heavy deposits, us patent No.8241869 (buchner et al) discloses a dry anaerobic fermenter operating on a plug flow basis, provided in the form of an elongated tubular vessel with overlapping stirring blades configured to push the deposits towards the discharge end and a suction plug for removing solid deposits from the reactor via an additional outlet. However, this solution does not solve the problem of separation of light impurities; it would therefore be desirable to provide a filtration station to treat the plastic-rich waste stream.

In addition, the above-mentioned difficult substrates (sand, stones, etc.) cause friction, and therefore, the equipment requires a robust feeding system.

A further challenge relates to increasing the capacity of AD equipment without compromising its economic viability in terms of capital investment. Conventional solutions include: increasing the number of reaction tanks per plant, which is not always possible due to the limited area; and/or providing an actuator that supports the agitation of the material and the travel of the material through the very long reactor. Thus, the exemplary solution according to us patent No.7659108(Schmid) relates to an apparatus for detecting and compensating for the sagging of the beater bar inside a horizontal anaerobic fermentation tank, in particular a horizontal anaerobic fermentation tank having a length of more than 50 meters.

Furthermore, according to the existing requirements set by the standards and regulations of the state and european union for anaerobic digestion processes of biodegradable raw materials, including regulation (EU) of committee 142/2011 of regulation (EC) No. 539/2006 "finnish fertilizer product act" and No. 24/11 "finnish fertilizer product act", as well as regulation No. 1069/2009 (EC) applied to animal by-products and derived products for non-human consumption, the decomposition products produced by the AD process must first be purified and then reintroduced into the ecosystem in the form of fertilizers, compost or soil amendments. In conventional anaerobic digester plants, this purification is carried out in a separate facility, usually located downstream of the digester reactor.

Typically, the DM content in the feed loaded to the dry AD reactor is significantly higher than in the wet process. Higher DM content results in lower thermal conductivity; therefore, dry reactors must have more powerful heating systems. Wet processes have high energy consumption and bring high costs to the recovery process. We note here that although a higher DM content is not essential in a dry fermentation reactor, the benefits of dry fermentation will be lost if the reactor intended for dry treatment is loaded with feedstock material suitable for treatment in a (cheap) wet AD plant.

The AD reactor setup is usually associated with the production of (bio) gas. In order to maximize the gas production, efficient mixing is required in all types of digestion processes. This remains a challenge for dry AD (fermentation) reactors due to the higher solids content of the feedstock.

In this respect, in view of the challenges to apply AD technology as part of a solid waste management system, there is still a need for revisions to technology related to anaerobic digestion in horizontally and continuously stirred reactors suitable for biogas production, and in particular, related to non-ideal removal of contaminants, blockage of outflow paths, inefficient mixing of materials in the digester, and/or low biogas production.

Disclosure of Invention

An object of the present invention is to solve or at least alleviate each problem caused by the limitations and disadvantages of the related art. This object is achieved by various embodiments of a reactor arrangement for anaerobic digestion of biodegradable organic substrates and related uses thereof. Accordingly, in one aspect of the present invention, according to the definition in independent claim 1, a reactor arrangement for anaerobic digestion of biodegradable organic substrates is provided.

In a preferred embodiment, the reactor comprises: at least one reactor tank extending horizontally, the tank having an inflow port at an entry end and at least one outflow port at a discharge end opposite the entry end; at least two agitators extending longitudinally, the agitators being arranged side by side within the interior of the tank; and a temperature regulation system configured to regulate temperature in the reactor tank and comprising a plurality of internal tubes configured to traverse in a longitudinal direction through lateral walls and/or a base of the tank and to convey a temperature regulation fluid along the plurality of internal tubes.

In an embodiment, the reactor arrangement is configured to transport the biodegradable organic substrate along the length of the reactor tank towards the discharge end such that: digested organic matrix is discharged from the tank through the primary outflow port and indigestible residue is discharged through the at least one secondary outflow port.

In an embodiment, the lateral wall defining the interior of the tank in the longitudinal direction is inclined, such that one or more inclined elements are formed along the entire length of the tank at the intersection between the lateral wall and the bottom. In an embodiment, each of said lateral walls comprises one or more substantially flat panels having an inclined element provided as a separate module.

In some embodiments, each agitator includes a drive rod having a number of blades mounted thereto. In an embodiment, inside the drive rod of the stirrer there is arranged the following internal tube: the inner tube is configured to convey a temperature regulating fluid along the inner tube.

In some embodiments, the temperature conditions within the tubes arranged in the lateral walls of the tank and the temperature conditions within the tubes arranged in the base of the tank are independently adjustable.

In an embodiment, the reactor arrangement further comprises a pre-treatment facility having at least one feed supply means configured to adjust the temperature of the organic substrate entering the at least one reactor tank to coincide with the temperature maintained in said tank.

In some embodiments, the reactor further comprises a sanitation system for thermally decontaminating the digested substrate. In an embodiment, the sanitation system is provided in an aftertreatment facility arranged downstream of the at least one tank.

In an alternative embodiment, the sanitation system comprises at least one enclosed conduit configured to traverse in a longitudinal direction through the lateral wall and/or base of the tank and receive digested substrate discharged through the main discharge port.

In an embodiment, the reactor arrangement further comprises a heat recovery and recycling system configured to recover heat generated in the at least one tank during anaerobic digestion and to direct the heat thus recovered to the pretreatment facility.

In some embodiments, the heat recovery and circulation system is further configured to direct the recovered heat to a temperature regulation system and optionally to a sanitation system.

In an embodiment, the heat recovery and recycle system comprises at least one heat exchanger unit for mediating heat transfer between the at least one tank and the pre-treatment facility.

In some embodiments, the reactor arrangement comprises several tanks arranged next to each other.

In another aspect, there is provided a use of a reactor arrangement for anaerobic digestion of organic waste, as defined in independent claim 16.

In a further aspect, there is provided a use of a reactor arrangement for biogas production, according to the content defined in independent claim 17.

The utility of the present invention arises from various reasons according to each embodiment of the present invention. First of all, the invention provides a compact reactor solution, the length of which is reduced by at least two times compared to a conventional AD reactor of the same type, wherein the reduced length is compensated by providing at least two reaction sub-zones arranged side by side. The absence of a separation wall between the stirrer units allows for efficient mixing of the digested substrate. By reducing the length of the reactor, excessive loads on the agitator and/or drive motor are avoided, thereby increasing the stability and reliability of the reactor, improving mixing efficiency, reducing energy requirements, and allowing substantial maintenance and repair costs to be saved.

Furthermore, the system for efficient sorting and recovery of effluents/residues provided within the reactor allows to treat "dirty" raw materials, including organic substrates heavily contaminated by various deposits and/or light impurities, such as for example plastic packaging and wrappers. An efficient sediment recovery system further prevents the formation of a solid layer on the bottom of the reaction tank and creates prerequisites for continuous flow dynamics therein.

Due to its pre-prepared construction mode, the disclosed reactor solution can be assembled easily and quickly on site. In addition, in the case of prefabricated construction blocks, the prefabricated construction blocks for the reactor are designed to be suitable for transport by conventional motor vehicles or platforms, including transport under standard bridges (e.g. highway bridges) and via highway tunnels; thus, no special transport is required.

The reactor solution disclosed herein also allows preheating of the feedstock such that the temperature of the matrix material approaches the temperature required for microbial activity when the matrix material enters the reaction space.

Furthermore, the reactor employs an integrated heat recovery and recycling (recirculation) concept, whereby the heat obtained during AD treatment inside the reaction tank is recovered for further storage and/or recirculation towards various facilities upstream and downstream of the reaction space. In addition, the heat thus recovered can be further used to regulate the temperature inside the reactor tank in order to obtain conditions that are most favorable to the bacterial population present inside said tank. As a result, the present reactor can be operated in a cost-effective manner at thermophilic conditions (42 ℃ to 97 ℃, preferably 42 ℃ to 66 ℃, in some cases 43 ℃ to 55 ℃) during the winter season in northern european climates.

The provision of a sanitising system incorporated inside the walls and/or base of the reactor tank increases the compactness of the overall solution and naturally eliminates the need to build a separate purification facility. Similarly, the integrated system of hollow tubes for circulating a temperature-regulating fluid inside the walls and/or base of the reactor tank further allows fine-tuning of the reaction conditions within the system, creating the most favourable environment for the biodegradation of the microorganisms present in the tank. By adjusting the temperature inside the reactor, the population of mesophilic and thermophilic bacteria can be adjusted, thus changing the production of biogas accordingly.

Overall, the reactor disclosed herein meets the requirements necessary for efficient digestion of (organic) waste fractions under anaerobic conditions in a cost-effective manner, namely: maintaining constant temperature conditions throughout the reactor facility (including the feeders); uniform and efficient mixing throughout the length of the reactor tank; and uniformly supplies the raw material.

The expression "organic substrate" refers in the present disclosure to a substrate material of biological origin; whereas the term "biodegradable" refers to a (organic) matrix that is naturally decomposed and/or decomposed due to the biological activity of microorganisms. The term "anaerobic" in this disclosure refers to a biodegradation process that is carried out in the absence of oxygen.

The expression "a number of" is used in the context of this document to denote any positive integer starting from one (1). The expression "plurality" means here any positive integer starting from two (2), for example up to two, three or four.

Various embodiments of the present invention will become apparent by consideration of the detailed description and accompanying drawings.

Drawings

Fig. 1A, 1C and 1D schematically show a reactor arrangement 100 for anaerobic digestion according to an embodiment. Fig. 1B is a perspective view of a reactor arrangement 100 according to an embodiment. Fig. 1E shows a top assembly for the reactor arrangement 100 according to an embodiment.

Fig. 2A, 2B, and 3 illustrate exemplary configurations of the reactor arrangement 100.

Fig. 4A-4D schematically illustrate cross-sectional views of reactor tanks 101 for use in various configurations of reactor 100.

Fig. 5A is a longitudinal cross-sectional view of the reactor arrangement 100 in an exemplary configuration. Fig. 5B is a plan view of the anaerobic digestion arrangement 100, viewed from the top, according to an embodiment.

Fig. 6 shows the reactor tank 101 according to an embodiment, viewed from the side.

Fig. 7 schematically illustrates a heating and temperature regulation system within the reactor arrangement 100.

Detailed Description

Detailed embodiments of the present invention are disclosed herein with reference to the accompanying drawings. Like reference numerals are used to refer to like elements throughout. The following references are used for the following components:

100-reactor arrangement for anaerobic digestion,

101-a reactor tank, wherein the reactor tank is provided with a plurality of reaction chambers,

201-optionally a post-treatment facility with a mechanical part,

202-means for the discharge of the deposits,

203-means for discharging the digested substrate,

301-a feed tank with an (optional) lid 311,

302-a first feed supply means,

401-a pre-treatment facility-the pre-treatment facility,

402-second feed supply means (temperature adjustable),

501A-top for reactor support structure(s),

10. 10A, 10B-the interior of the reactor tank,

11. 11A, 11B-lateral (wall) profile,

12. 12A-the base element and the corresponding extension of the base element,

13-an outer insulation/gasket,

14-an external base element, which is,

15. 501-cover and top respectively above the reaction tank,

16. 17-an inlet end and a corresponding discharge end,

18-the inlet port of the flow-in pipe,

19. 20, 21-an outflow port,

22-stirrer

23-the transmission rod/shaft/axle/s,

24. 24A, 24B-mixing blades and mixing blade components,

25-a separation device for the liquid to be separated,

26-a recess for receiving the drive rod,

27-driving the bar-supporting element or elements,

30-a sanitary system for the sanitary system,

31. 32, 33-flow ducts, jackets and extraction apertures for sanitary systems according to embodiments,

40-a temperature regulation system for the temperature of the sample,

41. 42-tube(s) inside the walls and base of the reactor tank,

43-tube(s) inside the drive rod,

44-a heat recovery and recycle system,

50-the heat exchanger unit or units,

51-a central heat distribution and control unit,

fig. 1A-1C schematically illustrate, at 100 below, the concept of various embodiments of an anaerobic digestion reactor arrangement, hereinafter reactor, 100, according to aspects of the present invention. The arrangement 100 advantageously comprises at least one reactor tank or basin 101, a pre-treatment facility 401 and a post-treatment facility 201. The pre-treatment facility advantageously comprises

various feeders

302, 402, several storage vessels 301 for storing raw material, chemicals, buffers etc. and various mechanical solutions. The aftertreatment facility 201 advantageously includes a discharge vessel 202, a heat recovery and heat purification solution, and optionally a mechanical solution.

Fig. 1B shows an exemplary arrangement 100 configured as an anaerobic (bio) digestion plant, comprising two reactor tanks 101 (see top 501), the reactor tanks 101 having a common pre-treatment facility 401 and a common post-treatment facility 201 with a discharge facility. The various devices (e.g., 301, 302, 402) configured for pre-treating and feeding feedstock material into the tank(s) 101 may be located in a separate "treatment" hall (fig. 1B, left monument, fig. 5B) and/or in a pre-treatment section disposed upstream of the tank(s). The elements indicated by

reference numerals

301, 302, 401 and optionally 402 are device-specific (depending on the size of the device, the substrate, the climatic conditions, etc.) and may vary in various embodiments. Preferably, the feed supply device 402 configured for thermal treatment of organic feedstock is provided substantially unchanged in each of the embodiments described herein and/or understood by those of skill in the art based on the present disclosure.

The reactor arrangement 100 advantageously comprises: a temperature adjustment system configured to adjust a temperature in the reactor tank (or tanks); and a heat recovery and recycling system configured to recover heat generated in the tank(s) during anaerobic digestion and direct the heat recovered thereby to the pretreatment facility 401 and optionally to a temperature adjustment system. The mentioned system will be described in further detail below.

Thus, the reactor arrangement 100 comprises a horizontally elongated tank 101, the tank 101 constituting a reaction chamber (reaction space). Thus, in some preferred embodiments, the reactor tank 101 has the following dimensions as expressed in terms of length x width x height: 21m × 12m × 6m to 7 m.

The reactor tank 101 is defined by a horizontally extending quadrilateral vessel having an inlet end 16 for receiving the organic feedstock and a discharge end 17 for extracting digested slurry (digestate). For purposes of clarity, in the present disclosure, the terms "digestate" and "digested substrate" refer to any substantially solid by-product of anaerobic digestion other than biogas. Feedstock supplied from a feed tank (or feed tanks) 301 in a pretreatment facility 401 is received into the reactor tank 101 through a feed inlet port 18 (inflow port) provided at the entry end 16.

In a preferred embodiment, the reactor tank 101 is rectangular at the bottom of the reactor tank 101. In this case, the width of the canister is the same at the inlet end and the discharge end.

In some other embodiments, the reactor tank 101 may be configured as a quadrilateral body having a width at the discharge end 17 that is greater than a width at the entry end 16 (not shown). At the base of the quadrilateral body, this configuration forms an upside-down isosceles trapezoid (with the narrower base of the isosceles trapezoid at the entry end 16).

The reactor tank 101 has disposed within the interior 10 of the reactor tank 101 at least two agitators or mixers 22 positioned side-by-side and extending in a longitudinal direction through the entire length of the reactor tank, which in this disclosure is defined as the distance from the entry end 16 to the discharge end 17.

As mentioned above, the stirrer shaft should not be too long. On the other hand, the capacity of the AD reactor tank must be at least 800m³(ii) a Otherwise the stability of the reactor conditions is compromised. Both requirements are met by providing a tank with dual mixing shafts, i.e. two shafts positioned next to each other.

The agitators may be arranged strictly parallel (in the case of a "rectangular" tank 101), or the agitators are preferably no more than 45 degrees off the longitudinal axis of symmetry in each direction (in the case of a "trapezoidal" reactor tank 101).

Each stirrer 22 comprises a drive rod 23, which drive rod 23 is configured as a shaft with several mixing blades 24. The shaft is advantageously provided as a tubular body having a wall thickness in the range of from 30 to 70mm, preferably in the range of from 50 to 70mm, further preferably in the range of from about 60 to 65 mm. In some embodiments, the mixing blades 24 are configured as blade blades (vanes) that fit to the drive rod, respectively, to follow a generally radial pattern (fig. 2A, 2B) or a generally helical pattern (not shown). In some alternative embodiments (not shown), each mixing blade may be configured as an open impeller comprising a series of vanes attached to a central hub fitted to the drive rod 23. The agitator may also be configured as a helical ribbon impeller (not shown).

Fig. 1C shows an exemplary configuration of a reactor comprising mixing blades 24 configured as paddles made of

separate parts

24A, 24B. The innermost part 24A (dashed box) of each blade is provided as a pair of tubular elements which can be passed through the shaft 23 and secured, for example by welding, whereby the amount of mechanical stress caused to the blade is minimal and the entire shaft structure is given torsional rigidity. The innermost component 24A may be secured to shaft(s) 23 already located at the manufacturing facility. The attachment of the outermost component 24B to the innermost component 24A may be achieved, for example, via a bonded coupling, followed by welding.

To facilitate the transport of an approximately 20m long shaft(s), the outermost component 24B may be fastened to the innermost component 24A at the location where the reactor arrangement 100 is assembled. As can be seen in fig. 1C, other identical mixing blades 24 are mounted on shaft(s) 23 such that each successive blade is rotated 45 degrees relative to the preceding blade. These positions are fixed. For example, the outermost ends of the mixing blades 24, represented by Roman numerals (ii) and (iv) on FIG. 1C, point in four general directions, namely, north (N) -south (S) and east (E) -west (W), respectively; while the blades indicated by the numbers (i) and (iii) point in four intermediate directions, namely southwest-northeast and northwest-southeast, respectively. In the above example, compass directions are used.

In the case where the reactor tank 101 follows a trapezoidal shape, the series of vanes 24 are preferably configured to gradually increase in diameter in a direction toward the discharge end 17.

The lever 23 is preferably motor driven. At least one motor engine, preferably an electric motor (not shown), may be provided in the mechanical part provided in the aftertreatment facility 201 and/or the pretreatment facility 401. In some cases, at least one additional drive mechanism may be mounted on the exterior of the tank 101 adjacent the inlet "front" end 16 of the tank 101 to mate with a main motor engine disposed on the "rear" of the reactor within the mechanical section. By providing at least two motors at both ends of the reactor tank, overloading of the stirrer can be avoided. The mechanical portion may also include additional mechanisms such as various controllers, amplifiers, and the like.

It is also preferred that the gearbox and motor head are arranged in a region within the pre-treatment facility 401. By this arrangement, the sealing structure for the agitator can be replaced even when the reaction tank(s) is filled with the matrix material.

In order to provide the most efficient agitation of the reaction substrate within the reactor tank 101, the agitator 22 is set to rotate in the opposite direction (as indicated by the arrows on fig. 2A, 2B); the reaction substrate is thus directed from approximately the center of the tank 101 towards the sides of the tank and then back to the center. The preferred rotation pattern is also shown in fig. 4A (direction of arrows drawn) where the agitator on the right side of the reactor tank 101 (as viewed from the inlet end 16) is set to rotate clockwise and correspondingly, the agitator on the left side is set to rotate counterclockwise. In other configurations, the agitators 22 may be set to rotate toward each other (right-counterclockwise; left-clockwise); or alternatively, the agitators 22 may be set to rotate in the same direction.

The arrangement of blades 24 in a radial and spiral/serpentine pattern on drive rod 23 is preferably such that the spacing between each blade 24 at intake end 16 is greater than the spacing at discharge end 17. The increase in the density of the blades per unit distance along the drive rod 23 allows for an efficient treatment of the reaction substrate, i.e. mixing of the reaction substrate, which in turn decreases as the reaction substrate travels along the length of the tank 101 from the inlet end 16 towards the discharge end 17, since the organic substrate dissolves inside the reactor due to anaerobic digestion.

Reactor 100 is preferably configured as a horizontal Plug Flow Reactor (PFR) for continuous stirred anaerobic digestion treatment of organic substrates. In the present disclosure, the term "anaerobic digestion" refers to the process by which microorganisms degrade organic matter and concomitantly produce biogas under anoxic conditions over a wide temperature range. Based on the temperature range, two sub-processes can generally be determined: mesophilic digestion, carried out in the range of 10 ℃ to 48 ℃, preferably in the range of 30 ℃ to 42 ℃, and thermophilic digestion in the range of 42 ℃ to 97 ℃, preferably in the range of 42 ℃ to 66 ℃, and in some cases in the range of 43 ℃ to 55 ℃. Thus, microorganisms that are stable and active within the ranges indicated above are mesophilic and thermophilic microorganisms.

In fact, according to the Brock Biology of Microorgansims (Brooks microbiology) (12 th edition, Madigan, Martinko, Dunlap and Clark), thermophilic Microorganisms are subdivided into: thermophilic bacteria such as Geobacillus stearothermophilus (Geobacillus stearothermophilus) active in the range of 42 ℃ to 66 ℃, optimally at 60 ℃; hyperthermophiles 1(hyperthermophiles1) such as Thermococcus celer, which are active in the temperature range of 67 ℃ to 97 ℃, most preferably at 88 ℃; and hyperthermophiles 2, such as corydalis fumarii (Pyrolobus fumarii), which are active at temperatures above 100 ℃. For the purposes of the present invention, the thermophilic temperature range is defined as 42 ℃ to 97 ℃.

An exemplary representative of a mesophilic microorganism is E.coli having an optimum temperature of about 39 ℃.

Mesophilic microorganisms show the improvement of the efficiency and the yield of the biogas production; however, thermophilic microorganisms are also more sensitive to changes in temperature, pH level, redox potential, and the presence of inhibitory factors such as heavy metals, antibiotics, and detergents. To the extent that the above parameters are adjusted to suitable values, the reactor 100 provided herein can be configured to operate with mesophilic microorganisms, thermophilic microorganisms, or with both types of microorganisms present in the reactor tank at the same time. As the organic matrix material travels through the reactor 100, the organic matrix material gradually dissolves due to the activity of the microorganisms.

Thus, during bacteria-mediated anaerobic digestion, the biodegradable organic substrate is broken down to produce biogas and a substantially solid residue, commonly referred to as digestate. The digestate comprises fibrous material (cellulose and lignin), dead bacterial cells, and a sludge-like fraction containing solids and methanogenic liquid. These byproducts may further be used as fertilizer, compost, low-grade building materials such as fiber board, and/or as feedstock for ethanol production.

The feed input for the reactor 100 is mainly represented by organic wastes of plant or animal origin, such as field (plant) biomass and by-products (bagasse, bran, straw), kitchen and catering (biological) wastes, household and/or municipal wastes, by-products of the food industry, forestry, agriculture (farming, animal and poultry raising), and sewage slurries and waste water sludges.

Obviously, the above starting materials vary widely in terms of purity. In this regard, the field biomass and crop byproducts, for example, are substantially free of indigestible or non-digestible impurities, or the field biomass and crop byproducts contain negligible amounts of indigestible or non-digestible impurities in the form of gravel or sand. Household or agricultural biowaste, on the other hand, typically contains a large amount of contaminants represented by difficult to digest plastics and/or metals, as well as various non-digestible organic by-products such as, for example, industrial by-products of wood and/or wood processing.

In order to effectively treat these hard to digest parts present in the reaction substrate travelling through the reactor tank 101, in particular from the inlet end 16 towards the discharge end 17 along the length of the reactor tank, the reactor arrangement 100 further comprises the following means: the appliance is used to sort and separate the digested substrate from the hard-to-digest residue and extract the digest-containing portion and the residue-containing portion from the tanks 101 independently of each other.

With further reference to fig. 3, fig. 3 shows a reactor tank 101 (after-treatment facility 201 not shown) within the reactor arrangement 100. Thus, the reactor tank 101 includes a feedstock receiving inflow port 18 at the inlet end 16 and at least one outflow port at the discharge end 17 opposite the inlet end 16. In some configurations, the reactor includes

several effluent ports

19, 20, 21 at the discharge end 17. Biodegradable organic substrate containing feedstock (F) fed from a feed tank (not shown) via pretreatment facility 401 enters reactor tank 101 through the inflow port 18. As mentioned above, the feedstock (F) includes various solid, difficult to digest contaminants suspended in the feedstock.

The biodegradable organic matrix material contained in the feedstock undergoes a process of anaerobic digestion by means of mesophilic and/or thermophilic microorganisms, with the feedstock (F) travelling along the length of the reactor tank 101 while being continuously stirred by at least two stirrers 22. At the same time, heavy, non-buoyant, hard-to-digest sediment such as stones, gravel, sand, glass, metal particles, etc. are dragged down by their own weight to settle at the bottom of the tank 101, while light, buoyant, hard-to-digest residues, such as for example plastics, float to the surface of the organic matrix material and reside there. In conventional digesters having an inlet and an outlet, such hard to digest contaminants must be manually removed when the reactor(s) are emptied to avoid clogging the discharge path and/or to avoid the formation of a sediment layer on the bottom of the reactor tank. The formation of the sediment layer causes an increase in the base level, thereby altering the flow dynamics generated upon agitation.

The reactor arrangement 100 may be configured to allow for continuous and efficient removal of difficult to digest contaminants from the reaction space 101 during the digestion process. Thus, digested substrate (digestate), as indicated in fig. 3 with capital letter D, may be discharged from the reactor tank 101 via the primary outflow port 19, while non-buoyant, hard-to-digest residue R1 (sediment) may be discharged via the first auxiliary outflow port 20. The digested matrix D thus obtained is free of solid, poorly digestible material or contains insignificant or negligible amounts of poorly digestible impurities. In any case, the digested substrate D does not require further purification and/or refinement.

The reactor 100 may also include a second auxiliary outflow port 21, the second auxiliary outflow port 21 being configured to receive light, buoyant, indigestible residue R2 (buoyant material), such as various non-recyclable plastics (plastic wrap, foam, etc.). Accordingly, in some cases, the

auxiliary outflow ports

20 and 21 may be arranged directly below or above the main outflow port (see fig. 3, port 21). Alternatively, either of the auxiliary ports 20, 21 (see fig. 3, port 20) may be displaced laterally within a horizontal plane related to the position of the main port 19. In some other cases, the at least one

auxiliary outflow port

20, 21 may be arranged at the same level as the main outflow port 19.

The reactor arrangement 100 may further comprise several devices configured to: the separation and classification of solid, indigestible material suspended in anaerobically digested organic matrix material is mediated as the organic matrix material travels along the length of the reactor tank 101 towards the

effluent ports

19, 20 and/or 21.

In the next configuration, the reactor arrangement 100 comprises sediment discharge means 202 (fig. 1A, 2B) configured to convey the buoyancy-free indigestible residue R1 from the bottom of the tank 101 to outside the reaction space via the first auxiliary outflow port 20. The device 202 is arranged at the discharge end 17, optionally the device 202 is located within the aftertreatment installation 201, and the device 202 is configured as at least one conveyor, such as a screw-type conveyor designed to collect solid deposits, e.g. gravel and sand, that accumulate on the bottom of the tank 101 and slowly travel (due to agitator-mediated agitation) towards the discharge end 17. Thus, in the embodiment shown on fig. 2A and 2B, 101, the device 202 comprises: a conveying screw provided in the tank 101 and arranged in a substantially horizontal plane; and a second conveying screw 202, the second conveying screw 202 being disposed within the rising pipe so as to convey the deposited residue R1 upward before the deposited residue R1 is taken out of the reactor 100. After removal from reactor 100, the solid, non-buoyant sediment is collected for recovery. Alternative configurations include a single elevated or non-elevated conveyor, such as, for example, a screw-type conveyor. In any event, any other suitable implementation may be utilized. Also shown on fig. 5A is a device 202 disposed within the reactor arrangement 100.

In some configurations, reactor 100 further comprises additional residue discharge means (not shown) configured to convey buoyant, indigestible residue R2 present on the surface of organic substrate material travelling along the length of reactor tank 101 to outside the reaction space via second auxiliary outflow port 21. Possible configurations of this additional residue discharge means include a conveyor configured to convey the lightweight plastic residue R2 in a horizontal plane and/or downward for further collection and recycling.

Fig. 2B shows the following exemplary configuration: in this exemplary configuration, the reactor 100 also includes several separation devices 25 located within the reactor tank 101, the separation devices 25 serving to facilitate separation of the indigestible (both buoyant/floating and non-buoyant/sedimentary) material suspended in the organic matrix. The separating apparatus 25 may be configured as a vertical bar having a lower end fixed to the bottom of the tank 101, said bar being set to perform a vibrating or oscillating movement. The wand is preferably motor driven. Separation device 25 is preferably positioned adjacent discharge end 17 of tank 101 to facilitate separation of digested (biodegradable) organic products from the hard-to-digest solids and, correspondingly, to facilitate sorting of digested product D and residues R1 and/or R2 toward

suitable effluent ports

19, 20 and/or 21.

In some configurations, reactor tank 101 includes several, optionally identical,

effluent ports

19, 20, 21 for discharging (unseparated) digestate D. In this case, the separation of the indigestible residue takes place elsewhere. All outflow ports may be located at the same level or at different levels. It should be noted that more than three outflow ports may be provided per canister.

With further reference to fig. 4A-4D, fig. 4A-4D illustrate various embodiments of the reactor arrangement 100 in cross-section of a reactor tank 101. In this regard, the tank 101 is defined by lateral walls (side walls) in the longitudinal direction. In order to achieve a more efficient mixing of the reaction substrates in the reactor tank 101 and to avoid deposit accumulation at the corners formed at the intersection between the (lateral) wall profiles and the bottom, each lateral wall defining the interior 10 of said reactor tank 101 in the longitudinal direction is inclined (slanted). Thus, an inclined element, indicated by the capital letter S, is advantageously formed along the entire length of the reactor tank 101 at the corner or intersection where the lateral wall meets the bottom.

Fig. 4A shows the following exemplary configuration: in this exemplary configuration, each lateral wall is defined by several L-shaped profiles 11; whereby the tilting element S is incorporated into each L-shaped profile portion, respectively. The tilting element S is shown by a dashed line in fig. 4A.

In the configuration of fig. 4A, the L-shaped profiles 11 forming the lateral walls are advantageously positioned opposite each other and joined at the bottom by one or more base (central) elements 12, so that at least two

adjoining sub-sections

10A, 10B are formed within the interior 10 of the reactor tank 101, wherein each sub-section 10A, 10B is configured to receive a stirrer 22 (not shown; the direction of rotation is depicted by the arrows). The base element(s) 12 are thus provided in order to form a raised partition between the

sub-sections

10A, 10B. The height of the partition may optionally be increased by mounting an extension element(s) 12A on the partition. In some configurations (not shown), the central base element(s) 12 (as shown in fig. 4A) may be provided as a generally flat panel(s) having individual divider elements optionally mounted thereto.

The individual L-shaped profiles 11 are positioned opposite each other in pairs, in order to comply with the principle of mirror symmetry. The L-shaped profile 11 is configured such that externally defines the reactor tank 101 as a rectangular tank at the base of the tank, while the inner surface of the tank 101 is curved to accommodate at least two agitators 22 within at least two

adjoining sub-sections

10A, 10B, respectively.

Fig. 4B to 4D show preferred configurations of the reactor arrangement 100.

Thus, fig. 4B shows the following configuration: in this configuration, each lateral wall is formed by a substantially flat vertical panel 11A. For each lateral wall 11A, the tilting element (S) can be provided as a separate module 11B.

In some configurations, the lateral panels forming the side walls are provided about 450mm thick, while the panels forming the head end (front and rear)

walls

16 and 17 are correspondingly provided about 550mm thick. The mentioned panels are preferably manufactured by casting or moulding, such as e.g. continuous moulding. As shown in fig. 4C, a plurality of (here, two) holes or recesses 26 are formed in each of the

end plates

16, 17 to accommodate the shafts 23. Additional support for the shaft is further provided by providing support/stiffening legs 27 at each

end

16, 17 of the tank 101 (fig. 1C, 6). The legs 27 may be provided as concrete slabs of approximately 600mm thickness.

In a preferred embodiment, the arrangement 100 comprises at least two reactor tanks 101 placed next to each other (fig. 4D). In this case, two adjacent reactor tanks advantageously share a lateral wall 11, which lateral wall 11 may be provided as a partition wall between the two reactor tanks (see fig. 4D, 5B). Nevertheless, it does not seem to be necessarily feasible to provide more than four reactor tanks arranged side by side due to thermal expansion. In the case of more than four cans positioned side by side, a moving seal is required.

The inclined surface may be curved (fig. 4A) or flat (fig. 4B). The oblique (declined) angle (theta ) may vary from about 35 degrees to about 60 degrees; preferably, the inclination angle may be set to about 45 degrees. Fig. 4C and 4D show a reactor configuration including a single inclined element 11B having a slightly curved inclined surface.

In the configuration shown in fig. 4B-4D, the base element 12 is provided as a substantially flat panel (e.g. 600mm thick); thus, at least two agitators 22 are received in the unseparated interior 10. In a further configuration (not shown), the arrangement of the base element may be realized in the manner shown in fig. 4A. Thus, the reactor tank as shown in fig. 4B may further comprise a separate dividing element (not shown) to separate the interior 10 into at least two sub-sections. Each tilt module 11B is in turn provided as an elongated block or several consecutive blocks extending through the entire length of the tank 101.

To ensure efficient mixing of the materials within the reactor tank 101, the reactor tank 101 is configured with a substantially flat bottom, as shown in fig. 4B-4D.

The reactor 100 also advantageously comprises at least one layer of external padding and/or insulation 13 (fig. 4A, 4B). The reactor tank 101 is also placed onto the base element 14 and sealed from the top by a flexible or rigid cover 15 (fig. 1C, 1D, 4C, 4D).

Although biogas is the end product of the bacterial digestion of the organic raw material entering the reaction space, most biogas is produced during the digestion process, and therefore the reactor 100 is advantageously equipped with an inflatable cover and/or top for storing biogas. The flexible cover 15 is provided as an expandable layer or several layers which, when expanded, may be housed in a fixed, rigid dome-shaped roof structure 501 (fig. 1A-1E). In some cases, the cover 15 may be constructed as a rigid fixed structure (dome-shaped or flat), in which case the reactor is advantageously equipped with a biogas extraction system (not shown).

It is generally preferred that the top structure for the reactor arrangement 100 be constructed as a two-membrane structure comprising an inner membrane layer 15 and an outer membrane layer 501. The outer layer 501 is typically aerated with air and is configured to maintain the shape of the outer layer even in the absence of biogas production activity in the reactor tank(s) 101. The outer membrane 501 may be configured to cover several reactor tanks 101 at a time (each reactor tank being covered with the inner membrane 15), for example: one reactor tank at a time (fig. 1B, fig. 1C) or several reactor tanks at a time (fig. 1D, fig. 1E). The inner membrane 15 is typically formed by an inflatable gas tight membrane when biogas is produced inside the reactor tank. The double membrane may be removed from one or more tanks for repair and maintenance. This action requires the removal of both membranes for safety reasons (restoring an air/oxygen rich atmosphere in a typical anaerobic tank). While maintenance work is being performed in a single tank, the other tanks in the reactor arrangement may still be operating properly (although in some configurations the outer membrane 501 has been removed).

In some configurations, a roof 501A (fig. 1B, 1C) of a building or other support structure incorporating or housing a reactor tank(s) for anaerobic digestion is disposed at an angle. In the example shown in fig. 1B and 1C, the wall of the pre-treatment side 401 (feed side) is about 9m high, while the wall of the post-treatment side 201 (output side) is about 6m high. In this configuration, each reactor tank 101 is covered by a double membrane (layers 15 and 501). The reactor installation as shown in fig. 1B, 1C is particularly suitable for geographical locations with a substantially mild climate, which eliminates the risk of snow and rain accumulating between the roofs.

Fig. 1D and 1E show the following reactor arrangements: in this reactor arrangement, the reactor tanks 101-1, 101-2 are covered by a common top (outer membrane 501). This configuration is achieved without the inclined roof structure. The reactor installation shown in fig. 1D, 1E is particularly preferred in nordic climates, as it allows to avoid snow and rain to accumulate on the roof 501 (snow flows downwards from the roof 501).

The lateral profiles 11, 11A and/or 11B and the base (central) element 12 can be realized as precast blocks, preferably made of concrete (which are formed and hardened before being transported to the construction site). A typical concrete block or slab includes powdered portland cement, water, sand, and gravel. In some cases, the heavy sand and gravel in the concrete block may be replaced, for example, with light expanded clay or expanded clay aggregate. In some cases, pre-cast cinder blocks may be used in which the gravel and sand described above are replaced with coal and/or cinder.

The wall structure and the base structure are preferably made of concrete and moulded in situ (in the field where the reactor is assembled).

Additionally or alternatively, the aforementioned profile may be made of metal. Metal-based configurations include solutions consisting of a metal sheet and optionally a core. In some embodiments, the

lateral walls

11, 11A are concrete slabs and the tilting modules 11B are metal-based blocks. Complete metal-based configurations are not excluded.

In some embodiments (not shown), the reactor tank 101 may include several base (central) elements 12 positioned side-by-side to form at least two partitions extending in parallel in the longitudinal direction, thereby forming at least three contiguous sub-sections within the interior 10 of the tank 101. This configuration allows to position at least three stirrers 22 arranged in parallel inside the reaction space 10.

Preferably, the reactor arrangement 100 further comprises a sanitation system 30 (fig. 3, 4A, 4B, 5B) for thermally decontaminating the digested substrate. The sanitization system 30 is configured for post-treating the digested substrate D via inhibition and/or inactivation of microorganisms contained in the digested substrate (thus, reversible or irreversible loss of microbial activity); thereby eliminating or at least reducing epidemiological risks.

Thus, the sanitation system 30 is configured to transfer heat as a stream of thermal energy to the digested substrate; thus, the attenuation/elimination of microbial activity is heat-induced. For example, sanitization is carried out at a temperature of 70 ℃ for 1 hour; and sanitized at a temperature of 100 ℃ for 20 minutes; thus, the flow rate through the means forming the sanitary system has been adjusted accordingly.

In a preferred configuration, the sanitation system 30 is disposed in an aftertreatment facility 201 disposed downstream of the at least one tank 101. The sanitary system 30 can be combined with the following discharge devices 203: the discharge means 203 is configured to collect digested substrate D from the number of tanks 101 and transport said digested substrate out of the reactor arrangement 100 (fig. 5B). In some configurations, the device 203 may be configured as a conveyor, such as, for example, a flight conveyor, and the sanitation system 30 may be built around the conveyor to establish the heating jacket. Alternatively, the discharge means 203 may be configured as a heated conveyor or conduit for transporting digested substrate from several tanks 101 towards an outlet.

Regardless of whether the digested substrate requires post-treatment, i.e. sanitization, the device(s) 203 configured as, for example, a piping system, may be used for heat recovery via, for example, several heat exchanger units 50 (fig. 5B).

In some alternative configurations, the sanitation system 30 may be incorporated into a sloped element S (fig. 3, 4A, 4B) formed inside the reactor tank 101. In this case, the sanitary system comprises at least one catheter 31 enclosed in a sheath or sheath 32. Heat is transferred to the conduit(s) 31 via the jacket(s) 32. The one or more conduits 31 are configured to traverse in a longitudinal direction through the lateral walls and/or base of the tank 101 and receive digested substrate discharged through the main discharge port 19.

The conduit(s) 31 may be configured to traverse each lateral wall defined by several L-shaped profiles 11 (fig. 4A) through the reactor tank 101. Whether or not the L-profiles are formed by concrete slabs, in order to accommodate the sanitary system 30 in the L-profiles, each of said slabs comprises a prefabricated through opening which, when the reactor tank is assembled, forms a hollow tubular tube or channel. Alternatively, the conduit(s) 31 may be configured to traverse through the tilt module 11B (fig. 4B). Additionally or alternatively, the conduit(s) 31 may be incorporated into the base (central) element(s) 12.

The sanitation system 30, implemented as shown in fig. 3, 4A, 4B, is configured to receive digested substrate D discharged from the reactor tank 101 through the main exit port 19 to mediate the travel of said substrate D from the discharge end 17 along the at least one conduit 31 to the entry end 16, whereupon microorganisms present in said digested substrate are inhibited and/or inactivated and post-treated (sanitised) substrate D1 is extracted through the at least one aperture 33 arranged at the entry end of the reactor tank 101. The post-treated digested substrate D1 withdrawn from the entry end 16 of the reactor 100 is further transported elsewhere for storage or transport.

Fig. 3, 4A, 4B show a sanitary system 30 provided in the form of a single U-or Y-shaped conduit passing from the main outflow port 19 (at the discharge end 17) through both lateral walls, in particular through the inclined elements S of the lateral walls, towards an aperture 33 arranged at the inlet end 16. Alternatively, the conduit extending through each lateral wall 11 may be provided as a separate element. Thus, as the digested substrate D travels along the sanitary system 30 arranged to "penetrate" the enclosing ducts 31 of the lateral walls 11 in the longitudinal direction, the digested substrate is decontaminated by thermal post-treatment.

A heating jacket or other heating means (fig. 3, 5B) disposed within the sanitation system 30 advantageously comprises a heat transfer appliance in communication with the heat generating apparatus. Preferably, the heat required for purification is obtained from a heat recovery and recycle system 44 (FIG. 5B) described further below. Thus, heating may be achieved via liquid circulation. Additionally or alternatively, heat transfer may be mediated by means of an external heat exchanger or heat pump. Exemplary locations for the heat exchanger 50 are shown in fig. 3 and 5B.

The reactor arrangement 100 further includes a temperature adjustment system 40, the temperature adjustment system 40 configured to regulate the temperature in the one or more tanks 101. The system 40 comprises a plurality of internal pipes 41, 42 configured to cross in a longitudinal direction through the lateral walls 11 and/or the base 12 of the tank and to convey the temperature-regulating fluid along the internal pipes accordingly (fig. 4A to 4C). The temperature within the reactor tank 101 is maintained at a level suitable for the normal functioning of the bacterial population essential for anaerobic digestion by means of the temperature regulation system 40.

In order to house the temperature adjustment device 40 into the reactor tank 101, the

elements

11, 11A forming the lateral wall and/or the base element(s) 12 may be provided as concrete slabs having a preformed hollow core of a plurality of hollow tubular tubes 40. The diameter of the tube forming the device 40 is preferably smaller than the diameter of the tube forming the conduit 31. For the sake of clarity, reference numeral 41 further designates a tube arranged in the side wall 11, whereas reference numeral 42 designates a tube arranged in the base element 12. The pipes 41 and 42 are disposed within the temperature regulation system 40.

In some embodiments, the tubes 41, 42 further comprise the following (e.g., metal) tubing: the pipes are enclosed in the concrete slabs forming the

lateral walls

11, 11A and/or the base (central) element(s) 12 or the internal lining/coating to reduce the wear of the concrete slabs. A coating, such as for example a metal coating, is preferably applied before assembling the

blocks

11, 11A, 12.

The temperature regulating fluid is a glycol compound, such as ethylene glycol or propylene glycol, for example. Alternatively, the temperature adjusting liquid may be water. By circulating a heating fluid through the pipes 41, 42, the temperature within the reactor tank 101 is maintained high enough for either mesophilic digestion (10 ℃ to 8 ℃, preferably 30 ℃ to 42 ℃) or thermophilic digestion (42 ℃ to 97 ℃, preferably within 42 ℃ to 66 ℃, in some cases 43 ℃ to 55 ℃).

The tubes 41, 42 forming the temperature regulation system 40 may be arranged into a substantially closed loop recirculation path, wherein the temperature regulation fluid is recirculated between the tubes 41, 42 and a heat recovery and circulation system 44, described further below, and optionally at least one external heat source (not shown). To create a recirculation path, in some configurations, the wall element of the head end or the L-shaped profile of the head end may be provided with a pre-formed turn and/or pipe bend therein.

Referring to fig. 6, in several configurations, an inner tube 43 is disposed inside the drive rod 23 of each agitator, the inner tube 43 being configured to convey the temperature adjustment fluid along the inner tube 43. As mentioned above, the stirrer shaft(s) is/are provided as a tubular body which is hollow inside. A tube 43 formed inside each of the stirrer shafts is used to convey a temperature adjusting fluid, such as glycol or water, along the tube and provide additional heating to the substrate being stirred in the reactor tank 101.

A temperature regulating fluid (e.g., glycol) is fed into the tube 43 at the discharge side 17. The fluid circulates through the shaft 23 in the direction of the inlet end 16 (indicated by the arrows in fig. 6) and back. The shaft is preferably equipped with a rotational coupling at least at the discharge end 17 to allow the temperature regulating fluid to be directed into the tube 43 during rotation of the agitator shaft 22.

Providing a temperature regulating liquid inside the shaft allows to equalize the microbial activity over the entire length of the reactor tank.

It is further preferred that the temperature conditions within the tubes 41 arranged in the lateral walls of the tank 101 and within the tubes 42 arranged in the base of said tank can be adjusted independently via several local temperature control units (not shown) and/or via a central heat distribution and control unit 51 (fig. 7). Providing independent temperature control for each of the walls and bottom of the reactor tank 101 allows for proper distribution of thermal energy to locations within the tank where material deposits and deposits are most likely to occur, such as locations where the substrate is moving slowly or is otherwise impeded.

In a similar manner, the temperature conditions within tube(s) 43 inside the stirrer shaft(s) can be controlled independently of the temperature in tubes 41 and/or 42.

The temperature adjustment system 40 is preferably disposed in communication with a heat recovery and circulation system 44 that includes at least one heat exchanger 50 (fig. 3, 7). Excess thermal energy released via the temperature regulation system 40 and/or the sanitation system 30 may be further supplied to the pretreatment facility 401 and/or extracted for further utilization.

In some configurations, tubes 41, 42 and 43 establish a temperature regulation system 40 and provide (internal) temperature regulation fluid circulation within the reactor tank. The reactor 100 also comprises a so-called external fluid circulation system configured to circulate (recirculate) the fluid substantially outside the reactor tank, also referred to as system 44 for heat recovery and recycling (recirculation)/reuse.

The system 44 configured for efficient recovery and reuse of the heat generated during anaerobic digestion forms one of the core features of the reactor 100 (fig. 5B, fig. 7). The system 44 is preferably configured to transfer heat from the output side (facility 201) to the feedstock supply side (facility 401). In addition, the heat recovery and recycling (recirculation) system 44 is preferably configured to communicate with the "internal" temperature adjustment system 40 and direct heat recovered therefrom to the system 40 and optionally to the sanitation system 30.

Fig. 7 illustrates an exemplary configuration of the

systems

40, 44 within the reactor 100. The temperature adjustment system 40, including the pipes 41, 42, 43 and incorporating the reactor tanks 101-1, 101-2, is shown in dashed lines. The heat recovery and recycling (recirculation) system 44 is provided as a network of interconnected pipes or conduits configured to transfer heat obtained during anaerobic digestion (17, 201) towards the pretreatment facility 401 and the

various devices

301, 302, 401 in the pretreatment facility 401. As mentioned above, heat transfer occurs via liquid circulation.

We note here that the

systems

40 and 44 form an integrated ensemble for heat recovery, circulation and temperature control. In the present disclosure, the systems are indicated by different reference numerals to provide the reader with a better understanding of the heat recovery function of the reactor arrangement 100.

Each of the

systems

40, 44 advantageously comprises several local heat exchange units 50 and a temperature control unit, such as a thermostat (not shown), to detect and adjust temperature conditions in the reactor arrangement 100.

Integrated control of the

systems

40, 44 is achieved via a central heat distribution and control unit 51 (fig. 7). Preferably, at least one heat exchanger unit 50 is provided within the heat recovery and recycle system 44 to mediate heat transfer between the tank(s) 101 (digester discharge side) and the pretreatment facility 401 (fig. 5B). In fig. 5B, heat transfer from the output (facility 201) to the input (facility 401) is shown by arrows (T).

Thus, one or more heat exchanger units 50 within the system 44 are provided for transporting thermal energy obtained from the anaerobic digestion process in the at least one reactor tank 101 to the pretreatment facility 401. Via the heat exchanger unit(s) 50, heat transfer may be mediated between the post-treatment facility 201/sanitation system 30, the temperature conditioning device 40 and the pre-treatment facility 401 (in the indicated order). The heat extracted from the facility 401 may be stored, transferred for further use, and/or returned to the output side (facility 201).

In some cases, reactor 100 also includes a substrate recirculation means (not shown) for reintroducing a portion of the digested substrate into reactor tank 101. The portion (inoculum) is allowed to separate before the digested substrate enters the sanitation system 30. Preferably, at least one third of the digested substrate is poured back into the reactor 100 to maintain a stable bacterial population in the reactor tank. One or more conduits configured for transporting inoculum back into the reactor tank are not subjected to heat treatment.

The reactor 100 is configured for anaerobic digestion treatment of organic substrates, wherein the content of dry matter (solid matter) is 0 to 80 percent by weight (wt%), preferably 0 to 45 wt%. In most cases, the DM content of the organic substrate inside the reactor tank 101 is in the range of 10 wt% to 35 wt%; however, the above ranges may vary from case to case. In some embodiments, the preferred content of dry matter in the feedstock comprises about 35 wt%. The organic substrate entering the reactor tank 101 is kept in solid state, i.e. dry matter in the above-mentioned range of 30 wt% to 40 wt%. In special cases, where the dry matter content is equal to or exceeds 50% by weight, it is necessary to dilute the reaction substrate. The organic matrix with about 35 wt% DM dissolves while travelling along the length of the reactor tank 101, whereby the digested product D comprises about 25 wt% dry matter.

In some aspects of the invention, use of the reactor 100 for anaerobic digestion of organic waste is provided.

In another aspect, a use of the reactor 100 for the production of biogas is provided. As mentioned above, anaerobic digestion processes mediated by microbial activity result in the production of biogas. Biogas is mainly methane (50% to 70%) and carbon dioxide (30% to 40%) with traces of ammonia (NH)₃) And hydrogen sulfide (H)₂S) of a mixture. The biogas obtained from the reactor 100 is advantageously directed for further refining, for example for the production of biofuel.

Fig. 5A shows a cross-section of the anaerobic digestion reactor arrangement 100 along an (imaginary) longitudinal symmetry axis, while fig. 5B shows an exemplary layout of the arrangement 100 as seen from the top. Thus, the reactor arrangement comprises at least one reactor tank 101 (three tanks 101-1, 101-2 and 101-3 are shown on fig. 5B), a post-treatment facility 201 with heat transfer devices as discussed above, and a pre-treatment facility 401, the pre-treatment facility 401 comprising at least one feed tank 301 advantageously equipped with a lid 311 and several feed supply means 302, 402 configured to convey raw material in the direction of the tank 101.

The feed tank(s) 301 may be configured to receive either fully raw ("raw") feedstock or pre-pulverized feedstock. Where applicable, the pre-comminution is preferably carried out in a conventional mill or crusher prior to loading the raw material into the feed tank(s) 301. It is desirable that the size of discrete aggregates, such as feedstock pieces and/or solid residue/inorganic matter, entering the reaction space 101 does not exceed the size of two clenches (150mm to 200 mm). Whether or not the organic waste to be treated by the reactor 100 contains or is expected to contain larger aggregates and/or solid debris (e.g., stones, gravel or bovine bone), such waste should be pre-crushed in the manner described above.

On the other hand, in view of the above-described embodiments, reactor 100 may be loaded with impure substrates containing a necessary amount of difficult-to-digest residues, such as sand, stones and various plastic contaminants, regardless of whether the feedstock to be treated is substantially homogeneous and/or does not contain oversized aggregates.

The substantially impure feed is pre-treated in the first feed supply means 302 and the second feed supply means 402 before entering the reactor tank 101. The second means 402 for feeding the raw material into the reaction space 101 is preferably configured as a conveyor, e.g. a scraper conveyor, in the same way as the discharge means 203 discussed above. Preferably, the device 402 is configured to regulate the temperature of the organic substrates entering one or more reactor tanks 101 to coincide with the temperature maintained in the tank. The temperature-regulated feedstock delivered by the feed supply device 402 into the reactor tank(s) 101 is received into the reaction space through the inflow port 18 provided at the entry end 16.

In most cases, the feed supply means 402 is configured to thermally treat the organic feedstock by heating, since the temperature maintained inside the reactor tank 101 (especially the temperature maintained primarily by the temperature adjustment device 40) is typically higher compared to untreated feedstock. Accordingly, the need to adjust the temperature within the reactor tank 101 arises from the necessity to maintain important functions and activities of the microorganisms present. With some exceptions, the facility 401 may be configured to cool the incoming feedstock.

The means 302 configured to convey the raw material towards the storage (feed) tank 301 towards the heated conveyor 402 is preferably configured as a screw conveyor or a piston pump.

It is apparent to those skilled in the art that as technology advances, the basic idea of the invention is intended to cover various modifications included in the spirit and scope of the invention. The invention and its embodiments are thus not limited to the examples described above; on the contrary, the invention and its embodiments may generally vary within the scope of the attached claims.

Claims

1. A reactor arrangement (100) for anaerobic digestion of biodegradable organic substrates, the reactor arrangement comprising:

at least one reactor tank (101) extending horizontally, the tank (101) having an inflow port (18) at an inlet end (16) and at least one outflow port at a discharge end (17) opposite the inlet end (16),

at least two agitators (22) extending longitudinally, the agitators (22) being arranged side by side within the interior (10) of the tank (101), and

a temperature regulation system (40) configured to regulate the temperature in the at least one tank (101) and comprising a plurality of internal tubes (41, 42) configured to traverse in a longitudinal direction through lateral walls and/or a base of the at least one tank and to convey a temperature regulation fluid along the plurality of internal tubes.

2. The reactor arrangement (100) of claim 1, configured to transport biodegradable organic substrates along the length of the tank (101) towards the discharge end such that: digested organic matrix is discharged from the tank (101) through a main outflow port (19) and indigestible residue is discharged through at least one auxiliary outflow port (20, 21).

3. The reactor arrangement (100) according to any one of the preceding claims 1 or 2, wherein lateral walls defining the interior (10) of the tank (101) in a longitudinal direction are inclined, such that one or more inclined elements (S) are formed along the entire length of the tank at the intersection between the lateral walls and the bottom.

4. The reactor arrangement (100) according to any preceding claim, wherein each lateral wall comprises one or more substantially flat panels (11A) having the inclined elements (S) provided as separate modules (11B).

5. The reactor arrangement (100) according to any preceding claim, wherein each agitator (22) comprises a drive rod (23), the drive rod (23) having a number of blades (24) mounted to the drive rod (23).

6. The reactor arrangement (100) according to any preceding claim, wherein inside the drive rod (23) of the stirrer there is arranged the following inner tube (43): the inner tube (43) is configured to convey a temperature-adjusting fluid along the inner tube (43).

7. The reactor arrangement (100) according to any preceding claim, wherein the temperature conditions within the tubes (41) arranged in the lateral walls of the tank (101) and within the tubes (42) arranged in the base of the tank are independently adjustable.

8. The reactor arrangement (100) further comprising a pre-treatment facility (401) having at least one feed supply means (402), the feed supply means (402) being configured to adjust the temperature of the organic substrate entering the at least one reactor tank (101) to coincide with the temperature maintained in the tank (101).

9. The reactor arrangement (100) according to any preceding claim, further comprising a sanitation system (30) for thermally decontaminating digested substrate.

10. The reactor arrangement (100) according to any preceding claim, wherein the sanitation system (30) is provided in a post-treatment facility (201) arranged downstream of the at least one tank (101).

11. The reactor arrangement (100) according to any preceding claim 1 to 9, wherein the sanitation system (30) comprises at least one enclosed conduit (31) configured to traverse in a longitudinal direction through the lateral wall and/or the base of the tank (101) and to receive digested substrate discharged through the main outflow port (19).

12. The reactor arrangement (100) according to any preceding claim, further comprising a heat recovery and recycling system (44) configured to recover heat generated in the at least one tank (101) during anaerobic digestion and to direct the heat thus recovered to the pretreatment facility (401).

13. The reactor arrangement (100) according to any preceding claim, wherein the heat recovery and recycle system (44) is further configured to direct the recovered heat to the temperature regulation system (40) and optionally to the sanitation system (30).

14. The reactor arrangement (100) according to any preceding claim, wherein the heat recovery and recycle system (44) comprises at least one heat exchanger unit (50), the heat exchanger unit (50) for mediating heat transfer between the at least one tank (101) and the pretreatment facility (401).

15. The reactor arrangement (100) according to any one of the preceding claims, comprising several tanks (101) arranged next to each other.

16. Use of the reactor arrangement (100) according to claims 1 to 15 for anaerobic digestion of organic waste.

17. Use of a reactor arrangement (100) according to claims 1 to 15 for biogas production.