- forming a print support structure for suspending a print head for printing the frame,

- suspending the print head on the print support structure for using the print head to print the frame,

- printing the frame using the print head by moving the print head with transfer equipment,

- removing the print head after completion of the printing process .

The invention is also related to a corresponding reactor frame and an arrangement for printing the reactor frame. Publication US 2017/0016244 Al is known as prior art, proposing construction of a tower-like structure by using 3D printing. However, such a printing method is not suitable for manufacturing reactor frames, since a frame structure constructed according to the above-mentioned technique would not resist the internal pressure existing in the reactor without an external support.

Unlike the special solution of the above-mentioned publication, the print head of 3D printing generally requires a separate print support structure, which enables the print head to move according to a programme , as well as its supporting during the printing process . The print support structure is removed after the printing process. Forming this print support structure causes additional costs in 3D printing. Traditionally, reactor frames have been manufactured at factories from steel constructions by welding, as proposed in publication FI 125284 B, or they are manufactured at the construction site from steel by welding or from concrete by casting, utilising moulds . However, such a construction is heavy in weight as well as expensive to manufacture and transport to the place of use and requires a significant amount of work on site.

An object of the invention is to provide a method that is better and more advantageous than prior art methods for printing a reactor frame with a 3D printer in such a way that the frame complies with the strength requirements for the frame. The characteristic features of this invention are set forth in the appended claim 1. Another object of the invention is to provide an arrangement that is better and more advantageous than prior art arrangements for printing a reactor frame that complies with applicable strength requirements. The characteristic features of this invention are set forth in the appended claim 8. Still another object of the invention is to provide a reactor frame that is better and more advantageous than prior art reactor frames complying with applicable strength requirements. The characteristic features of this invention are set forth in the appended claim 21.

The object of the method according to the invention can be achieved with a method for manufacturing a reactor frame using 3D printing, the reactor frame being impermeable and arranged tocontaina liquid, wherein the frame is manufactured in the following steps, in which a print support structure is formed for suspending a print head for printing the frame, the print head is suspended on the print support structure for using the print head to print the frame and the frame is printed using the print head by moving the print head with transfer equipment. In the method, an external skeleton required by the frame and separate from the frame is produced as a mountable structure before printing the frame for supporting the part of the frame to be printed from the outside against the internal hydrostatic pressure existing in the frame. The skeleton is arranged to function as a print support structure for the print head and to form guides for moving the print head along the guides by means of transfer equipment. Furthermore, in the method, at least part of the frame is printed using the print head in such a way that the printed part of the frame leans to said skeleton and the frame-external skeleton remains as part of the frame after the removal of the print head. Finally, the print head is removed after completion of the printing process.

By printing at least part of the frame to connect to a frame-external skeleton, it is possible to form a reactor frame that resists to the internal hydrostatic pressure, advantageously using printable material, since the skeleton provides a force opposing to the internal pressure . At the same time, the skeleton, which is necessary in terms of frame resistance and which can be erected before printing the frame , functions as a print support structure . Thus , the printing process can be performed without a separate print support structure, which otherwise would need to be disassembled or removed after the printing process . By printing the frame on site, it is possible to avoid, among other things, manufacturing and transport costs related to a heavy steel or concrete construction. Advantageously, the frame walls are formed by printing . Thus, frame walls can be produced by 3D printing as the print head circulates, leaning to the skeleton, forming a wall against the skeleton.

The floor of the frame can also be produced by casting with or without the print head. Casting the floor is a simple operation and the mould required in it is notably simple.

Advantageously, the print head is guided along a circular path by the print support structure thus forming the frame walls as a continuous print, layer by layer. In this way, the construction, being essentially seamless, becomes particularly strong and resistant . Advantageously, the frame ceiling is formed by casting. Forces acting on the frame ceiling are notably lower than those acting on the frame walls , since the hydrostatic pressure inside the reactor frame only affects the walls and the floor. Thus, the ceiling can be implemented in a simple way by casting.

Advantageously, fibre-reinforced concrete is used for printing. Fibre included in fibre-reinforced concrete strengthens concrete being, however, printable. Thanks to fibres, sufficient strength is achieved with fibre-reinforced concrete for the printable part of the frame so that the printable part can be supported to the skeleton only for a part of its area. The printing material can also be a plastic compound, metal, recycled glass supplemented with necessary support materials. According to an embodiment, a sliding mould is used in the method in connection with the print head at least for the inner surface of the frame. With a sliding mould, the inner surface can be made smooth thus preventing biomass inside the reactor from sticking to grooves or irregularities or to both.

In the method, according to an embodiment, transverse beams are formed in the skeleton for supporting the frame to be printed and for supporting the print head. These transverse beams serve both as components that provide support for the printable frame of the skeleton and as guides of the transfer equipment for the print head .

Advantageously, an overhead crane is used in the method for suspending the print head and moving it on the transverse beams for carrying out the printing. These transverse beams contribute to the supporting of the frame walls from the outside . Furthermore, when using an overhead crane to move the print head, it is possible to use a practically prefabricated prior art overhead crane construction, which is economically realisable and extremely reliable .

In connection with the print head, it is possible to use a feed device for fitting an injection hose in the printable part of the frame. With the injection hose, resin can be injected into the printable part, into the lift joint of the print. Using such a procedure, adhesion and compactness of the layer to be printed can be ensured. Alternatively, a heating apparatus can be included associated with the print head for partly melting the layer of a previously printed frame part to improve adhesion of the new layer, if the material to be printed is plastic or metal, for example. The object of the arrangement according to the invention can be achieved with an arrangement for printing a reactor frame, the arrangement including a print head for printing the frame at least partly, a print support structure for supporting the print head in the vicinity of the frame to be printed, transfer equipment for moving the print head along the print support structure for printing the frame, and guides for supporting the print head. The guides are a part of a separate external skeleton belonging to the reactor frame and supporting the printable part from the outside . The guides and the skeleton form the print support structure. The arrangement according to the invention can be implemented without a separate print support structure that is generally used in 3D printing, which brings cost savings in terms of both material usage and work steps . In other words, when using an arrangement according to the invention, the external skeleton necessary for strengthening the reactor frame and which later remains as a part of the frame can be used as the print support structure. In this way, disassembly of a separate print support structure is avoided after printing the reactor frame.

Advantageously, the transfer equipment includes a first carriage comprising a frame and wheels arranged to be supported to the skeleton. With the first carriage, a good extension length is achieved for the print head over the entire frame to be printed.

The first carriage is advantageously an overhead crane to which said print head is connected, the overhead crane being arranged to be moveable on the guides for printing the frame. An overhead crane is well known prior art and thus an advantageous alternative for moving the print head during printing.

Advantageously, the transfer equipment includes a second carriage connected to the first carriage with wheels. The second carriage enables the use of a movement direction transverse to the movement direction of the first carriage for moving the print head.

The transfer equipment advantageously includes vertical printer guides pivoted by the end to the second carriage with a vertical joint and a third carriage arranged on the printer guides for moving the printer head in the vertical direction. While the first carriage and the second carriage enable the print head to be moved in the direction of the floor level, the third carriage enables a movement direction perpendicular to these directions, i.e., a vertical movement direction. Furthermore, pivoted guides enable the print head to be turned by 360 ⁰ for orienting the print head . Alternatively, the vertical movement of the print head can also be provided with chains, when the print head is moved with an overhead crane. The arrangement may include measuring equipment arranged in the vicinity of the print head for measuring printing properties. This measuring equipment can be optical, for example, advantageously a measuring device based on ultrasound technology, for measuring the printing height. The measuring equipment can consist of a measuring device based on laser technology for measuring the printing thickness . Thus, the measuring device can be used to verify the position of the outer and inner edges , i.e., width. The measuring equipment can also be arranged to measure tightness, density and reinforcement and to save the results in a 3D model, for example. Thus, for example, a scanner based on wave radar technology can be applied as measuring equipment for measuring and monitoring the density and texture of the print as well as layers. In this way, it is possible to monitor the printing properties advantageously in real time and make changes to the composition of the stock to be printed or printing parameters or to both during printing .

The print head can also include motion sensors and positioning equipment.

Advantageously, the arrangement includes a control unit for the print head. The control unit can be used to control print head movements by controlling the transfer equipment and material input by controlling the pump drive.

The arrangement advantageously includes a sliding mould arranged in the vicinity of the print head for spreading the material to be printed in layers with uniform sides. With a sliding mould, it is possible to make the inner surface of the reactor smooth.

According to an embodiment, the arrangement includes equipment placed in the vicinity of the print head for adding link elements to the material to be printed in order to improve print adhesion. For example, this equipment can consist of a roll, a guiding device and a motor, wherein a carpet containing link elements is uncoiled from the roll onto the previous layer during printing. Alternatively, the equipment for adding link elements may consist of a robotic crab, which installs separate link elements on the previous printing layer.

According to an embodiment, the arrangement includes coating equipment near the print head for coating the frame during printing . Thus, it is possible to install an insulation layer or similar, for example, on the surface of the part printed.

According to an embodiment, the arrangement includes a vibrator near the print head for compacting the material to be printed. The use of a vibrator is particularly advantageous, if the material to be printed is fibre-reinforced concrete, which can be efficiently compacted by vibrating.

Advantageously, the print head includes a separate nozzle for printing insulation material. In this way, for example, it is possible to fill the positions for the inlet and outlet openings on the walls with insulation material thus avoiding the need of cutting openings in the frame with expensive methods. An interim storage space may be included in the transfer equipment for the material to be printed. A certain amount of material employed in printing can be pumped to the interim storage space; therefore, a hose is not necessary between the main storage space and the print head during printing, which facilitates the movability of the print head during the printing process.

Advantageously, the arrangement according to the invention may include a container arranged in the vicinity of the transfer equipment serving as an interim storage space for the stock to be printed when pumping the stock to the print head from the main container located outside the reactor frame.

In the arrangement, the walls are advantageously made of fibre-reinforced concrete. Fibre-reinforced concrete is relatively inexpensive and yet a strong material, which can be 3D printed on site.

In the arrangement, the skeleton is advantageously arranged to be fastened to the bottom. This makes it possible to rigidly fasten the external skeleton so that the skeleton cannot move when the pressure inside the reactor frame presses the reactor frame outwards towards the skeleton. Advantageously, the arrangement additionally includes a container for the material to be 3D printed, i.e., rawmaterial, a feed channel connecting the container to the print head for supplying raw material from the container to the print head, and a pump arranged in the vicinity of the feed channel for supplying the material to be 3D printed from the container to the print head along the feed channel .

The object of the reactor frame according to the invention can be achieved with a reactor frame which includes a floor, walls and a ceiling arranged to form an impermeable construction for keeping the liquid pressure inside the reactor frame, wherein at least the walls have been manufactured by 3D printing. The frame includes a frame-external skeleton arranged outside the printed part of the frame for supporting the printed part from the outside, this support structure being a mountable structure and arranged to function as the print support structure for the print head of 3D printing and as guides for moving the print head during printing and to remain as part of the frame after the removal of the print head. In the reactor frame, at least the walls lean to the skeleton. Such a reactor frame can be manufactured at the place of use thus avoiding high transport costs. On the other hand, the frame can be manufactured using an inexpensive material, since the external skeleton included therein provides adequate strength for the frame, although the frame part to be printed is lower in strength compared to prior art constructions.

The external skeleton is advantageously a lattice beam construction. With a lattice beam construction, it is possible to achieve high constructional strength, and a lattice beam is easy to transport as ready-cut parts to the site of manufacture where it will only be assembled.

The walls are advantageously made of fibre-reinforced concrete. Fibre-reinforced concrete is notably less expensive for its unit price compared to steel and yet it provides sufficient strength together with an external skeleton. Fibre included in fibre-reinforced concrete makes it stronger than normal concrete and increases the breaking strength of the printed frame. With a method, arrangement and reactor frame according to the invention, large savings are achieved in terms of material and transport costs. Material savings may amount to as much as several tens of percentage points, since the material required for the frame to be printed can be purchased on site.

In the reactor frame, the skeleton includes transverse beams with a spacing of 0.5 m - 8.0 m, preferably 2.0 m - 4.0 m. Thus, the span between the transverse beams is sufficiently small for the frame to be printed to resist to the reactor-internal pressure applied to the span without breaking.

Advantageously, the width of the reactor frame is in the range of 2 m - 20 m, preferably 6 m - 15 m, the height is between 2 m and 20 m, preferably between 6 m and 15 m, and the length is between 10 m and 100 m, preferably between 20 m and 60 m. In a reactor of this size class, forces existing inside the frame, such as the outwards force caused by the hydrostatic pressure, are so large that it is necessary to support the frame part to be printed from the outside with a skeleton.

Alternatively, the reactor frame can also be placed vertically, in which case its width is in the range of 2 m - 20 m, preferably 6 m - 15 m, height 12 m - 50 m, preferably 20 m - 35 m, and length 2 m - 20 m, preferably 6 m - 15 m. Thus, the reactor frame only takes a small amount of the floor space at the plant where the reactor will be located. On the other hand, the significance of the skeleton is particularly emphasised in this kind of embodiment, since the hydrostatic pressure inside the reactor frame is high due to a high column.

Advantageously, the reactor frame according to the invention includes inserts arranged as part of the frame walls. The purpose of these inserts is to function as a support structure for the shafts of agitation equipment installed in the reactor enabling the placement of a blade agitator, for example, inside the reactor frame .

Advantageously, the reactor frame also includes inlet and outlet openings for supplying raw material into the reactor frame and removing solid matter from the reactor frame. In this way, the reactor frame according to the invention can be used in a reactor for anaerobic digestion of biomaterial to produce biogas and digestate. Advantageously, the reactor then includes agitation equipment with which biomaterial can be moved in the reactor for optimising anaerobic digestion.

According to an embodiment, instead of a square shape, the reactor frame can also be circular, elliptical or another equivalent axially symmetrical part. In this case, hydrostatic pressure acting on the walls, caused by the biomaterial inside the reactor frame is more uniformly distributed to the walls and, thus, the skeleton can have a lighter construction compared to square-shaped reactor frames .

The invention is described below in detail by making reference to the appended drawings that illustrate some of the embodiments of the invention, in which: are longitudinal cross-sectional views of the frame illustrating the steps of the method according to the invention during the manufacture of a reactor frame according to the invention,

are top views of the frame illustrating the steps of the method according to the invention during the manufacture of a reactor frame according to the invention,

is a partial cross-sectional view of an embodiment of the reactor frame according to the invention during operation in a reactor, provide a top view and a cross-sectional view in the longitudinal direction of the frame of another embodiment of the reactor frame according to the invention.

Figures la - li illustrate an embodiment of the method according to the invention during the manufacture of a reactor frame according to the invention. Figures la - li are cross-sectional views of the reactor frame construction along the cross-section A-A of Figure 2a. To avoid freight costs, it is desired in the method according to the invention to avoid manufacturing an expensive and heavy reactor frame at the factory, therefore carrying out the manufacture at least partly directly at the place of use using material less costly than steel. In the method according to the invention, the frame-external skeleton is formed before the actual printing process. Advantageously, the external skeleton is a lattice beam frame, which is formed at least partly on site. The lattice beam frame or at least part of it can be pre-welded in the factory, in which case the lattice beam frame is only assembled at the place of use. According to Figure la, the forming of the external skeleton is advantageously started by casting the bottom 12 of the reactor frame onto a basement 100. Advantageously, the shape of the bottom can be rectangular, when manufacturing plug flow reactors, for example. The bottom is advantageously made of steel-reinforced concrete, in which case it is capable of carrying the weight of the reactor formed on top of it. Next, the walls 42 of the skeleton 18 circulating around the edges of the bottom 12 are erected on the bottom 12 and fastened to the bottom 12 and to each other with bolted joints, for example. The figures also depict an inlet or outlet opening 52, which has been formed on the wall of the skeleton 18 for supplying biomass to or removing it from the reactor. The number of walls 42 of the skeleton may be four. Although the walls 42 of the skeleton 18 are illustrated with a continuous beam in Figures lb - 2d, it is obvious to those skilled in the art that, rather than a solid structure, the walls are advantageously a lattice-like structure for cutting down weight . It is also otherwise obvious that the dimensions shown in Figures la - 2d do not necessarily reflect reality and are indicative only. After erecting the walls 42 of the skeleton 18, it is possible to install an arrangement according to the invention on the inner surfaces of the walls 42 of the skeleton 18 and on the bottom 12 for printing the reactor frame. According to Figures Id - lh, the arrangement 11 includes, as part of the frame 10, guides 38 forming the print support structure 24 for the frame-external skeleton 18, a print head 22 and transfer equipment 36 for moving the print head 22 along the guides. Transverse beams 32 or other support structures serve as guides 38 included in the arrangement 11, and their purpose is to deliver force generated by the pressure acting inside the reactor part to be printed to the external skeleton 18. The top-most transverse beam 32 together with the walls 42 of the skeleton 18 forms the print support structure 24 of the arrangement 11 , whereto the transfer equipment supporting the print head 22 (shown in Figures le - lh) can be supported, preferably by gravity, as shown in Figure Id. Advantageously, the transfer equipment 36 consists of an overhead crane 35, which is supported on the guides 38 formed by the top-most transverse beams 32. An overhead crane 35 can be driven on the guides 38 self-propelled over the entire range of the skeleton 18. The driving force used by the arrangement is advantageously either generated by self-propulsion using an aggregate or the arrangement is preferably connected to the local power network. According to Figure le, the print head 22 can be connected to the transfer equipment 36 by means of printer guides 44. These printer guides 44 can consist of a rail, which in turn is connected to a second carriage 48 of the overhead crane 35, which preferably functions as a first carriage 34 included in the transfer equipment 36. In turn, the second carriage 48 moves leaning to the frame 34a of the first carriage 34. In other words, the frame 34a and the wheels 34b of the first carriage 34 together with the guides 38 enable the print head 22 to be moved in the longitudinal direction of the reactor frame 10, while the second carriage 48 and the second guides 48c arranged in the frame 34a of the first carriage 34 and the second wheels 48b of the second carriage 48 enable the print head 22 to be moved in the transverse direction relative to the reactor frame 10. Furthermore, the print head 22 is advantageously connected to the vertical printer guides 44 by means of a separate third carriage 50 included in the transfer equipment 36 enabling the vertical movement of the print head 22. In turn, the printer guides 44 included in the transfer equipment 36 are advantageously connected to the second carriage 48 of the overhead crane 34 by means of a vertical j oint 49 , enabling the printer guides and thereby the print head to turn at least 360° for forming the walls of the frame part to be printed on each side. In other words, the axis of rotation of the vertical joint is vertical. Alternatively, the print head may include a turning nozzle providing orientation of the nozzle towards the various walls.

Advantageously, the arrangement according to the invention includes a control unit for the print head. The control unit advantageously includes a memory for the control codes, dimensional drawings and programmable means related to the printing of the reactor frame, a computational unit for performing calculations for programmable means, and measuring equipment for determining the nozzle position and the properties of the part printed. Advantageously, the control codes and drawings related to the printing of the part to be printed are entered in the control unit, where they are converted to control commands for the printing unit by programmable means. Control commands are used to move the print head transfer equipment , i.e., preferably the overhead crane, the second carriage of the overhead crane, the print head on the printer guides by means of the third carriage, as well as to rotate the printer guides relative to the carriage of the overhead crane. In addition, control commands are used by the measuring equipment to more accurately determine the movements of the print head and the properties of the part printed. The control unit also calculates the necessary movement speed for the print head and controls the feed pump, preferably included in the arrangement, used for supplying material. Advantageously, the control unit can be , for example, unit S7 manufacturedby Siemens . The print head can be, for example, a construction similar to the one proposed in publication Nylund, J et al "IMPLEMENTATION OF A CONTOUR CRAFTING SYSTEM TO A 3-DIMENSIONAL CONCRETE PRINTER" (10th International DAAAM Baltic Conference 'Industrial engineering' 12-13 May 2015, Tallinn, Estonia) . On the other hand, the construction of the print head is also illustrated at https : / /www . eteknix . com/3d-printer-reportedly-can-build-house -day/

and the construction of another print head on the website of Chinese WinSun Ltd:

http : / /www . winsun3d . com/En/Product /pro_inner/ id/ 1.

Thus, the print head can be implemented as any of the constructions mentioned above.

According to Figure If, the printing of the walls 14 of the parts 20 to be printed for the frame 10 is advantageously performed by spraying from top to bottom. The print head 22 advantageously moves continuously and prints a layer with a thickness of 50 mm - 80 mm during each cycle. Advantageously, the transfer speed of the print head is adjusted suitable according to the printing speed of the print head, i.e., the printing speed of the material, in order to maximise the layer to be printed while taking into account drying and ensuring that the material stays in place. At the same time, when the print head prints the material, it is possible to add link elements on top of the printed layer using equipment arranged near the print head to improve adhesion of the following layer and strengthen the wall being created. Figures 2a - 2d illustrate the method by which the print head 22 is made to circulate by the transfer equipment 36 for printing the walls 14.

Advantageously, the material used for printing is fibre-reinforced concrete, which dries to a strength of approximately 70% in 24 hours. Thanks to fibre included in fibre-reinforced concrete, sufficient breaking strength is achieved for the frame part to be printed so that the printed structure achieves sufficient durability with the transverse beam interval applied. Walls to be printed can also be reinforced in advance, in which case printing takes place from the lateral direction with the printing stock surrounding the reinforcement. In this way, the wall strength can be increased and, at the same time, the thickness of a layer printed in a single cycle can also be increased as the reinforcement supports the material printed.

Although only the printing of frame walls with the print head is described in this context, it is obvious to those skilled in the art that a separate floor can also be printed onto the bottom.

In addition to the nozzle for supplying the main printing material, the print head may include additional nozzles for also supplying insulation material, for example. As insulation material, it is possible to use foam glass, urethane or low-density concrete, for example. In addition, the print head can also be equipped with a separate nozzle for printing a coating. For example, the coating can be paint or other equivalent material .

The walls 14 to be printed according to Figure lg lean to the transverse beams 32 by their outer surfaces and thereby to the skeleton 18 external to the frame 10. The skeleton 18 provides a counter-force for the force acting on the walls generated by the pressure inside the completed reactor frame and thus prevents the walls printed from bending or breaking under the pressure. In the printing process, it is also possible to simultaneously use a sliding mould, which can be, for instance, a mould connected to the print head only inside the frame walls, against which the material is supported. Alternatively, the mould can be a part connected to the print head disposed on both sides of the wall. The entire printing of the walls can be performed by moving the print head with the third carriage in the vertical direction with the walls gaining height without the need to move the transfer equipment from one transverse beam to another as the walls are being created.

Once the walls 14 of the frame 10 have achieved the height projected, it is possible to either print or mould cast a ceiling 16 for the frame 10 between the walls 14. If the ceiling 16 is formed by printing, the printer guides 44 can be removed from the second carriage 48 of the overhead crane 34 and the print head 22 can be fastened directly to the second carriage 48 , since vertical height adjustment is no longer necessary. After this, the ceiling 16 can be printed using the same print head 22. Links can be added to the ceiling 16 at the printing stage utilising them during the construction of the ceiling structure 46 for the skeleton 18 by forming connections by means of transverse beams 32 between the frame ceiling 16 and the ceiling structure 46 of the skeleton 18, as shown in Figure li .

Once the frame 10 is entirely printed, the print head 22 and the transfer equipment 36 including the second carriage 48 shown in Figure lh are removed from the frame-external skeleton 18 and the skeleton 18 can be completed with the ceiling structure 46 according to Figure li to bind the walls 42 of the skeleton 18 to each other, thereby increasing the strength of the skeleton 18. According to the idea of the invention, the frame-external skeleton used as the print support structure for printing remains as a part of the reactor frame, the reactor frame can be manufactured without a separate step of dismounting the print support structure, and it is not necessary to transport the print support structure away. In addition, this method can be used to print reactors of different sizes by making slight modifications to the auxiliary frame of the printer's print head.

Advantageously, the arrangement according to the invention can include a container 54 arranged in the vicinity of the transfer equipment. Advantageously, the container 54 is located on top of the frame beam forming the first carriage 48 of the overhead crane 34 according to Figures lc - lh and 2a - 2d. The container 54 functions as an interim storage space for the stock to be printed when pumping the stock from the main container 56 located outside the reactor frame 10 to the print head 22. According to Figure 2d, stock pumping from the main container 56 to the container 54 located on top of the overhead crane 34 can be performed by the feed pump 58 along a supply hose 60 in accordance with the normal concrete pumping technique. The apparatus necessary for pumping is in this case only shown in Figure 2d, although it is naturally included in all printing steps.

The height of the layer printed in one printing cycle can be in the range of 10 mm - 300 mm, preferably 40 mm - 80 mm, depending on the composition of the material printed and the printing speed. The thickness of the walls printed can be in the range of 200 mm - 800 mm, preferably 400 mm - 600 mm. The reactor frame according to the invention can advantageously be used in a reactor for producing biogas from biomass by anaerobic digestion, the reactor including a horizontal or vertical channel-like frame delimiting a reaction space for plug flow of biomass and the reactor including at least three successive blocks including their microbial strains. In addition, the reactor includes agitation equipment arranged within the reactor frame for agitating biomass and feeding microbes into biomass and for advancing biomass in the reaction space, the equipment comprising a reject collection and feed system for collecting reject and feeding it to at least three blocks as high consistency stock, and recovery equipment for recovering biogas produced while the microbes consume the organic material of biomass . The use of a reactor frame according to the invention is particularly advantageous in the context of this type of reactor since, as the result of anaerobic digestion, the moisture content of biomass increases to a very high level and hydrostatic pressure is present inside the reactor frame.

Figure 3 is a partial cross-sectional view of a reactor frame 10 similar to the one set out above. For the agitation equipment 62, the walls 14 of the reactor frame 10 may include inserts 72, which are installed during the printing of the walls. These inserts 72 comprise a bearing assembly 64 for the agitation shaft 68 of the agitation equipment, by which the agitation equipment 62 is supported to the reactor frame 12. The agitation shaft 68 is advantageously fitted with a gearing assembly 74, which can be supported to the external skeleton 18, more precisely, to the walls 42 of the skeleton. Inside the frame 10, the agitation shaft is fitted with agitation blades 70.

According to Figures 4a and 4b, instead of the square shape of Figures la - 2d, the reactor frame 10 can also be circular, elliptical or another equivalent axially symmetrical part. In this case, hydrostatic pressure acting on the walls 14, caused by the biomaterial inside the reactor frame 10 is more uniformly distributed to the walls and, thus, the skeleton 18 can have a lighter construction compared to square-shaped reactor frames. This is particularly emphasised in the case of high reactor frames.