Method for manufacturing a reactor for biogas production

Abstract

The invention relates to a method for manufacturing a reactor intended for biogas production. The biogas is produced by anaerobic digestion of biofeedstock. The reactor comprises a tubular reaction chamber (10) formed by a bottom (2), walls (W), and a roof (4), and an external supporting frame structure (20) for the reaction chamber (10) to stiffen and support the reaction chamber (10) from the outside against forces caused by the feedstock. A supporting frame structure (20) is formed, which is provided with several vertical posts (21) on both sides of the reactor (1), as well as several horizontal anchoring elements (22), to which the concrete reinforcements (25) of the wall (W) are attached. The outer wall formwork elements (3a) are detachably attached between the vertical posts (21), in connection with installation elements (23) belonging to the vertical posts. The inner wall formwork elements (3b) are detachably connected to each other at a distance from the outer wall formwork elements (3a), so as to form, together with the outer formwork elements (3a), a wall formwork structure (3) comprising the horizontal anchoring elements (22) and a filling space (S). Concrete is cast into the filling space (S) within the formwork structure (3), whereby the concrete, upon drying, forms the wall (W) of the reactor chamber (1). The outer and inner wall formwork elements (3a, 3b) are detached from their attachments.

Description

[0001] METHOD FOR MANUFACTURING A REACTOR FOR BIOGAS PRODUCTION

[0002] The invention relates to a method for manufacturing a reactor for producing biogas, the reactor comprising a tubular reaction chamber formed from a bottom, walls and a roof, for processing feedstock into end products, and which reactor further comprises an external reaction chamber support frame structure for stiffening and supporting the reaction chamber from the outside against forces caused by the feedstock.

[0003] From the prior art, publication WO / 075298 Al is known, which discloses a reactor for producing biogas from biowaste. The reaction chamber of the reactor is a tubular structure comprising walls, a floor, and a roof.

[0004] In small reactors, the hydrostatic pressure remains relatively low, and the reaction chamber can be constructed as a relatively thin steel structure, with the wall thickness ranging from 100 to 150 mm.

[0005] The problem with the structure according to the above-mentioned publication, however, is that as the size of the reactor increases, the height of the feedstock bed in the reaction chamber also increases, thereby elevating the hydrostatic pressure exerted on the walls of the reaction chamber. In order to ensure that the reaction chamber is sufficiently strong to withstand the resulting stresses, the wall thickness of the reaction chamber must be increased in proportion to the height of the reactor. Increasing the width of prior art reactors is not reasonable, as this would increase the floor area required in production plants, increasing the need for covered space in the production plant and thereby the investment costs. Increasing the thickness of the walls of the reaction chambers in turn increases feedstock costs, hampers the handling of the reaction chamber and incurs high costs when transporting the reaction chamber as a whole from the manufacturing site to the place of use. Similar problems exist in the solutions disclosed in reference publications W02019102074 Al and W02009002112 A2.

[0006] The object of the invention is to provide a reactor for producing biogas through anaerobic digestion of biofeedstock, which reactor is more cost-effective in terms of manufacturing and transportation costs compared with prior art reactors. The characteristic features of the invention are disclosed in the accompanying claim 1.

[0007] The casing structure, formed using removable formwork elements after the concrete has been cast, results in a structurally optimized, cost-effective, and easily transportable solution for delivery to the installation site. The external support frame structure can be integrated into the walls and optionally the roof of the reactor chamber, which, upon completion, are made entirely of reinforced concrete. The general structure of the external support frame structure as such is known from prior art, for example from reference publications WO 2019102074 Al and WO 2022162279 Al, and in that respect, this structure can be incorporated as part of the teachings of the present invention. Similarly, the mixing devices disclosed in these publications are also considered integral components of such reactors, whereby their teachings may likewise be incorporated as part of this application.

[0008] The wall thickness and, if necessary, also the roof thickness achieved by this method can be reduced to half or even less compared with solutions of the prior art. Previously, the wall thickness has been approximately 700 millimeters for reactors of corresponding size, and about 350 millimeters for reactors employing a support frame structure. In particular, positioning the outer, as well as the inner wall formwork elements in a new manner in connection with the support frame structure during reactor manufacturing enables their removal after the concrete casting. The wall formwork elements can thus be reused in connection with the manufacturing of the walls and possibly also the roof of a subsequent reactor. The resulting material savings are significant. Previously, the formwork elements had to be left in the structure due to their positioning. The cost of the formwork elements per reactor may account for one third to one fourth of the total manufacturing costs of the reactor, representing a direct cost saving when using the method according to the present invention. Reducing the thickness of the concrete wall also results in substantial material and cost savings.

[0009] After the installation of the wall formwork elements, the casing is filled with concrete, whereby the reaction chamber is capable of withstanding the internal hydrostatic pressure generated by the biowaste with high liquid content during the slow anaerobic digestion process. The external support frame structure, fitted to the wall of the reaction chamber, stiffens and supports the wall formwork structure of even a large reactor from the outside during installation and concreting, as well as against the forces exerted by the feedstock on the chamber walls during reactor operation. This structure thus provides, in a novel and inventive manner, the above- mentioned advantages, such as enabling the manufacturing of reaction chambers of different sizes using mantle elements and support frame elements having as uniform size as possible.

[0010] In addition, the external support frame structure can be constructed, for example, by assembling tubular beams, forming a highly rigid yet relatively lightweight structure that supports both the mantle elements during installation and concreting and the reaction chamber from the outside during operation. Installation of the reactor chamber according to the invention is started by assembling the external support frame to support the outermost wall formwork elements of the casing structure. After the installation of the outer wall formwork elements, any remaining concrete reinforcements and heating pipes are installed. Thereafter, the inner wall formwork elements are detachably attached. It is also possible that instead of or in addition to concrete some other filling material may be used to stiffen and reinforce the mantle structure.

[0011] Preferably, the reactor is a plug-flow reactor. In this case the process can be continuous. The mixing and conveying devices are preferably supported by the external support frame structure in a manner known per se, as described in the above-mentioned prior art publications. The mixing and conveying devices enable the feedstock to be mixed in order to optimize biological activity and to be conveyed forward in the reaction chamber to promote anaerobic digestion. Supporting the mixing and conveying devices on the external support frame structure also contributes to the lightweight construction of the reaction chamber, as the loads from these devices are not are not solely imposed on the chamber walls, but are also distributed to the external support frame structure.

[0012] The reactor preferably also comprises devices for heating, digestate recirculation, automation, and gas recovery of the type known from the prior art. The heating devices are used to maintain the temperature of the reaction chamber at a sufficiently high level for anaerobic digestion. The digestate is in turn preferably always recirculated to the previous mixing zone in order to transfer the microbial population. Automation is used to control the mixing and conveying devices, heating devices, and digestate recirculation devices in order to maintain anaerobic digestion in a preferably continuous process. Such or similar devices are known for example from publication WO 2015 / 075298 Al.

[0013] Preferably, at least the walls of the reaction chamber, and advantageously also the roof, are formed from modular-sized outer and inner wall formwork elements. In this way, even structural components intended for the construction of a large-sized reaction chamber can be transported easily as significantly smaller elements or products from the manufacturing site to the place of use.

[0014] The height of the reactor can be 6 to 15 meters, preferably 8 to 10 meters. The hydrostatic pressure caused by the liquid material in the reaction chamber generates particularly high forces as the height of the reactor increases in pursuit of higher capacity.

[0015] The modular-sized wall formwork elements used in the walls of the reaction chamber can be 0.5 to 3.6 meters in height, preferably 0.5 to 2.4 meters. In this way, the elements are easier to handle compared with larger elements, and they can be tightly packed into standard shipping containers, minimizing unused space within the container.

[0016] The modular-sized wall formwork elements used in the walls of the reaction chamber may have a length of 1.5 to 10 meters, preferably 2 to 8 meters. This makes the handling of the wall formwork elements easier compared with larger elements, and allows them to be tightly packed into standard shipping containers, thereby minimizing unused space within the container. Separate corner elements are used at the external and internal corners.

[0017] The wall formwork elements of the reaction chamber may have a thickness of 2.5 to

[0018] 8 cm, preferably 4 to 8 cm. The material thickness of the wall formwork elements (i.e., the steel thickness) is preferably 2 to 5 mm, which keeps the weight of the factory-manufactured wall formwork elements of the reaction chamber moderate, thereby reducing transportation costs and material costs in the reactor's manufacturing.

[0019] Preferably, the wall formwork elements may be made of carbon steel. The wall formwork elements may also be made of stainless steel. Instead of steel, the mantle elements may also be made of, for example, composite, plastic or similar material having sufficient rigidity.

[0020] Preferably, concrete is cast into the filling space or casing between the mantle elements (and, if necessary, reinforcements such as rebar are added and / or reinforcing fibers are added to the concrete), but alternatively, a different material having sufficient strength may be used instead of concrete. Thickness of the completed wall mantle after the removal of the wall formwork elements is 30 to 50 cm.

[0021] Instead of steel, the external frame structure may also be made of, for example, composite, concrete or similar material having sufficient rigidity.

[0022] Preferably, the external support frame structure comprises vertical columns arranged at a distance from each other along the length of the reactor on both sides, transverse supports connecting the vertical columns across the width of the reactor, and longitudinal supports connecting the vertical columns along the length of the reactor on each side thereof. Such an external support frame structure is notably lightweight and can therefore be transported from the manufacturing site to the place of use with low transportation costs.

[0023] Implementing the reaction chamber of the reactor according to the invention preferably using mantle elements allows the reactor to be transported in shipping containers or containers suitable for road transport, and enables the delivery of larger reactors to customers even in locations with difficult access. An external support frame structure in turn provides the advantage that there is no need to increase the thickness of the wall of the reaction chamber (the mantle) as the size of the reactor grows, and additional supports are not required during the installation and concreting of the mantle elements. This does, however, not preclude the possibility of defining the width of the filling space or casing (i.e. the concreting width) at the installation site as necessary to achieve sufficient structural strength.

[0024] The invention is described in detail below with reference to the accompanying drawings illustrating some applications of the invention, in which

[0025] Figure 1 shows a cross-sectional view of the wall of the reactor according to the invention,

[0026] Figure 2 shows cross-section II-II taken from Figure 1,

[0027] Figure 3 shows a prior art support frame structure, with an example of the positioning of an outer and an inner wall formwork element,

[0028] Kuvio 4a shows an axonometric representation of the wall form element presented in Figure 2, comprising an opening,

[0029] Kuvio 4b shows a frame or framework according to a preferred embodiment of the invention, and

[0030] Kuvio 5 shows a reactor wall according to another embodiment of the invention.

[0031] The reactor according to the invention comprises in all embodiments thereof a tubular reaction chamber 10 and an external support frame structure 20 as shown in Figure 1. Accordingly, the structure of the external support frame 20 is in itself known from reference publications WO 2019102074 Al and WO 2022162279 Al, and is illustrated as prior art in Figure 3. In general, the external support frame structure 20 is provided with multiple vertical columns 21, or with lattice columns or pillars formed by two adjacent vertical columns 21a and 21b. These are arranged at a distance from each other along the length of reactor 1 on both sides of the reaction chamber 10. The vertical columns 21 located on opposite sides of the reaction chamber 10 are connected to each other at their upper ends by transverse supports 25, and optionally also by longitudinal supports. The operational reaction chamber 10 is formed by a base 2, walls W connected to the base, and roof 4 connected to the walls. The reactor wall structure formed by wall formwork elements (during manufacturing) is described in more detail below. The terms base, walls, and roof do not restrict their actual positioning within the reactor, but are used to facilitate understanding of the reactor structure in relation to the flow direction of the biofeedstock within the reactor. Naturally, the reaction chamber also comprises inlet and outlet openings through which the feedstock is introduced into space R defined by the base, walls, and roof of the reaction chamber 10, preferably by means of feeding devices included in the reactor. A more detailed description of these is provided in the aforementioned prior art publications, and therefore they need not to be discussed further herein.

[0032] Next, a preferred embodiment of the structure applying the method according to the invention is described with reference to accompanying Figures 1 and 2. Figure 1 shows a cross-section of one vertical wall of reactor 1 taken between two vertical columns. In this case it includes an external support frame structure 20, in itself of a known type, which is illustrated in the present embodiment and in Figure 3 as a lattice column 21 formed by two vertical columns 21a (inner column) and 21b (outer column), and diagonal braces 21c arranged between them.

[0033] To form the formwork structure 3 according to the invention, horizontal anchoring elements 22 are attached to each inner column 21a of the lattice column 21, the elements being rods made of metal, for example, reinforcing steel. Anchoring elements are arranged along the inner vertical column 21a at a distance from each other, for example, every 10 to 50 cm, one above the other, substantially along the entire length of column 21a. The free ends of the horizontal anchoring elements 22 of the vertical column thus extend a certain distance from the inner vertical column 21a towards the opposing vertical columns, preferably at the same level in the transverse direction of the reactor. The distance between the free end of horizontal anchoring elements 22 and the inner vertical column 21a is preferably approximately 10 to 30 cm. Said distance is, however, defined so that the free ends remain within the finished wall, preferably at a distance of 3 to 10 cm from the inner surface of wall W. The mounting elements 23 are also arranged on the inner vertical column 21a for detachably fastening the outer wall formwork elements 3a between the spaced vertical columns, in this case two inner vertical columns 21a. This is illustrated particularly in Figure 2, where the outer wall formwork elements 3a are shown installed. The mounting elements 23 are preferably vertically oriented strips or plates arranged on the surfaces of the vertical columns 21a that face the interior of the reactor. The mounting elements 23 are arranged to extend longitudinally along the reactor 1 on both sides of the vertical column 21a, preferably for a distance of about 2 to 10 cm. The outer surfaces 23' of the mounting elements are preferably aligned in the lateral direction of the reactor with the inward-facing surfaces of the inner vertical columns 21a. The mounting elements 23 may also be lugs that are arranged vertically at a distance from each other. The outer wall formwork elements 3a are thus supported at their edges against the outer surfaces 23' of the mounting elements 23.

[0034] Another preferred embodiment relating to the mounting elements 23 is shown in Figure 5. In this embodiment, the inner vertical column 21a is formed by a HEA beam, i.e., a beam having a transverse flange between two parallel flanges in the shape of the letter H. This forms the mounting elements associated with the vertical column 21a described above in such a way that one of the flanges 23 of the HEA beam serves as the mounting element. In this case, the outer wall formwork elements 3a can be inserted between the webs formed by the flanges and further against the mounting element 23 (flange).

[0035] Accordingly, detachable attachment of the outer wall formwork elements 3a belonging to the formwork structure 3 of the method according to the invention can be easily implemented between the vertical columns arranged at a distance from each other in connection with the mounting elements 23. At the same time, detachable attachment of the inner wall formwork elements 3b belonging to the formwork structure 3 according to the invention can also be implemented. Next, formation of one wall of the reaction chamber 10 will be described, applicable also in connection with the opposite wall, end walls, and the roof. First, the outer wall formwork elements 3a are installed between the adjacent inner vertical columns 21a in the direction of arrow Pl shown in Figure 2. Figure 3 presents a general view of the position of an outer wall formwork element 3a according to the invention within the external support frame structure 20, and Figure 4a shows the general shape of a wall formwork element 3a provided with an opening 4. In a similar manner, outer wall formwork elements 3a can be placed on top of each other and between successive adjacent vertical columns 21 in the longitudinal direction of the reactor 1. To facilitate placement and alignment, the outer wall formwork elements 3a, as well as the inner wall formwork elements 3b described below, are provided with edge flanges 3a' (3b9 or bends. In Figure 2, the outer wall formwork elements 3a are supported at their edge flanges 3a' against the side edges of the inner vertical columns 21a. Likewise, the vertically stacked outer formwork elements 3a are supported against one another at their edge flanges 3a'. The edge flanges 3a' extend outward from the actual form surface by approximately 2.5 to 8 cm, forming the above-mentioned thickness of the wall formwork elements. Figure 1 also shows the height H of one wall formwork element in relation to the height of the reaction chamber 10.

[0036] In the embodiment shown in Figure 5, the outer wall formwork elements 3a are wedged at their edges by using separate wedging means 23a and 23b, which are detachably installed between the flanges of the HEA beam 21a, such that the outer wall formwork elements 3a are supported against and / or pressed towards the mounting element 23 (one flange of the HEA beam 21a).

[0037] At this stage of the method, the concrete reinforcements 25 or equivalent wall reinforcements, which preferably form part of the formwork structure, can be attached to the horizontal anchoring elements 22 in an appropriate manner. In the transverse direction of the reactor 1, the attachment is carried out such that the reinforcements 25 are positioned in the space S(W) between the outer wall formwork elements 3a and the inner wall formwork elements 3b, which will be installed as described below. This empty space is denoted by reference numeral S, and the finished reactor wall 1 by reference numeral W (space S being converted into the completed wall in a manner according to the method). At the same stage, other reactor components, such as heating pipes (not shown), may also be installed within the space S.

[0038] After this, the inner wall formwork elements 3b are detachably fastened to each other at a distance from the outer wall formwork elements 3a. In this way, together with the outer formwork elements 3a, they form the horizontal anchoring elements 22 the wall formwork structure 3 comprising the necessary concrete reinforcements 25. The inner wall formwork elements 3b are brought in the transverse direction of the reactor against separate support elements 24", a preferred embodiment of which will be described below. According to a preferred embodiment, the positioning of an individual inner wall formwork element 3b relative to an outer wall formwork element 3a is shown in Figure 3. There the inner formwork element 3b preferably extends longitudinally across two vertical columns 21 of the reactor 1. Accordingly, its surface facing the outer wall formwork element 3a is supported against the support elements 24", at a selected distance from the free ends of the horizontal anchoring elements 22 and thus also from the surface of the outer wall formwork elements 3a. This is only an example of the positioning of wall formwork elements, and they may be arranged relative to each other as appropriate to form the formwork structure 3.

[0039] Each installed inner and outer wall formwork element 3a and 3b is locked to one another, preferably during installation, using several locking means. The locking means are preferably mechanical fastening devices 24. Here the locking means are, for example, formwork locks 24, the function of which is known per se in the context of formwork assembly. A longitudinal through-rod belonging to the formwork lock is passed through the edge of the outer wall formwork element 3a, the mounting element 23, the empty space S, and the inner wall formwork element 3b. In the embodiment of Figure 5, the through-rod is positioned laterally to the mounting element 23, so that it does not pass through it. In both embodiments, however, the locking elements 24' are tightened via the through-rod against the wall formwork elements so that the outer wall formwork element 3a is pressed at its edges against the mounting elements 23. The inner wall formwork element 3b is pressed into place between the support elements 24" (which remain on the side of the empty space S) and the formwork lock 24 in connection with the through-rod. Multiple fastening means are arranged for each mounting element 23, spaced apart from one another, in this case one above the other. The purpose of the fastening devices 24 is to ensure the structural integrity of the formwork structure against the pressure exerted by the concrete to be cast next into the space S.

[0040] In a preferred embodiment of the invention, the inner wall formwork elements 3b, which are supported against each other via edge flanges 3b' (see Figure 2), are connected to one another using fastening means 3', such as mechanical fastening elements forming a screw-nut connection. This further reinforces the part of the formwork formed by the inner wall formwork elements 3b against the pressure exerted by the concrete to be cast.

[0041] Furthermore, in a preferred embodiment of the invention, at least one of the outer and inner wall formwork elements 3a and 3b is provided with aligned openings 4 positioned at a desired location in the wall of the reactor 1. Before casting, a framework or frame 5 shown in Figure 4, which may be, for example, a frame 5 for an inspection window, is installed at the location of the opening 4. The edges 5a of the frame are dimensioned such that the frame 5 can be fitted into the opening 4 in a matched manner. The edges 5a are preferably provided with anchoring lugs 5b or equivalent anchoring elements 5b, which remain embedded in the cast concrete S, forming a structure-reinforcing bond between concrete S and the framework or frame 5.

[0042] Afterwards, when at least the formwork structure 3 for the wall to be cast, and preferably also the formwork structure for the roof to be cast in a similar manner, has been assembled, concrete casting into the formwork can be carried out. In other words, the empty space S is filled with concrete, thereby forming the wall W. Fibers reinforcing the structure can be added to the concrete mix. The roof formwork is only on the reactor chamber side. The roof structure of the reactor may also be a shell element or a hollow-core slab.

[0043] After the concrete has hardened, the outer and inner wall formwork elements 3a and 3b are detached from their fastenings. At this stage, any mechanical fastening means 3' are removed, and the locking elements 24' connected to the outer and inner wall formwork elements 3a and 3b are released. The possible support elements 24" remain embedded within the structure of the wall W. Thereafter, the wall formwork elements 3a and 3b can be removed, in this case, in the direction indicated by arrows P2 and P3 in Figure 1 so that they are fully disengaged from the fastening means 24. The ends of the through-rods of the fastening devices 24 may remain visible on the surface of the finished wall W. They can be cut flush with the wall surface and, if necessary, covered. The portion of the through-rod remaining inside the wall W will then contribute to reinforcing the structure of the finished wall W.

[0044] The removed wall formwork elements 3a and 3b can then be reused in the construction of another reactor.

[0045] The durability of the resulting structure is such that the width (wall thickness) of the finished wall W (side walls and end walls) is significantly smaller than in walls according to the prior art, i.e. being the aforementioned 30 to 50 cm.

[0046] The reactor is intended for producing biogas through anaerobic digestion of biowaste, such as household or agricultural waste, for example. As a result of anaerobic digestion, the moisture content of the feedstock increases with the progressing digestion, and the material inside the reaction chamber has a high moisture content, as the dry matter content of the material in the reaction chamber can advantageously range from 10 to 40 percent. This high moisture content, together with the high filling level of the reaction chamber, causes the material to exert hydrostatic pressure on the walls of the reaction chamber, which tends to push the walls of the reaction chamber outward. The filling level of the reaction chamber is advantageously such that the liquid surface extends 0.5 to 1.5 meters below the roof of the reaction chamber.

[0047] It should be noted that the roof 4 of reactor chamber 10 can be formed according to the method of the invention into a corresponding structure as the walls W.

[0048] An advantage of the reactor according to the invention when using such a reaction chamber is that significant material savings are achieved, as the walls and roof of the reaction chamber can be manufactured thinner and with thinner material thicknesses than those of prior art solutions.

[0049] It can be separately mentioned that in the reactor described above, the biofeed- stock moves essentially horizontally along the length of the reactor. The reactor can also be arranged vertically, in which case the floor 2 (and the roof) of the above-described embodiment is a vertical wall (like the other walls), and the biofeedstock moves vertically or essentially vertically. The term 'floor' therefore does not limit its placement. In such a case, the floor can have a structure similar to that of the walls W.

[0050] The reactor structure according to the invention, implemented with a thin reaction chamber and an external supporting frame structure, can also be used in other applications where there is a large amount of material having a high liquid content in the reactor, causing a high hydrostatic pressure in the reaction chamber.

Claims

Claims1. Method for manufacturing a reactor for producing biogas, in which reactor biogas is produced by anaerobic digestion from biofeedstock, the reactor comprising a tubular reaction chamber (10) formed by a bottom (2), walls (W), and a roof (4) for processing feedstock into end products, and wherein the reactor (1) further comprises an external supporting frame structure (20) for the reaction chamber (10) to stiffen and support the reaction chamber (10) from the outside against forces caused by the feedstock, characterized in that the method comprises the steps of:- forming a supporting frame structure (20) provided with a plurality of vertical posts (21) arranged at a distance from each other along the longitudinal direction of the reactor (1) on both sides of the reactor (1), and a plurality of horizontal anchoring elements (22) attached to the vertical posts (21), to which anchoring elements the concrete reinforcements (25) of the walls (W) are attached,- attaching the outer wall formwork elements (3a) detachably between the vertical posts (21) arranged at a distance from each other, in connection with installation elements (23)- attaching the inner wall formwork elements (3b) detachably to each other at a distance from the outer wall formwork elements (3a) to form, together with the outer wall formwork elements (3a), a wall formwork structure (3) comprising the horizontal anchoring elements (22) and a filling space (S)- casting concrete into the filling space (S) within the formwork structure (3), whereby the concrete upon drying forms the wall (W) of the reactor chamber (1)- detaching the outer and inner wall formwork elements (3a, 3b) from their attachments.

2. The method according to claim 1, characterized in that the inner wall formwork elements (3b) are positioned at a distance from the plane formed by the free ends of the horizontal anchoring elements (22).

3. The method according to claim 1 or 2, characterized in that the distance between the outer wall formwork elements (3a) and the inner wall formwork elements (3b) is 30 to 50 cm.

4. The method according to any one of the preceding claims 1 to 3, characterized in that the outer wall formwork elements (3a) and the inner wall formwork elements (3b) are locked to each other via fastening means (24).

5. The method according to claim 4, characterized in that the fastening means are formwork locks (24).

6. The method according to claim 4, characterized in that the fastening means (24) comprise support elements (24"), against which the inner wall formwork elements (3b) are supported at a desired distance from the outer wall formwork elements (3a).

7. The method according to any one of the preceding claims 1 to 6, characterized in that at least one of the outer and inner wall formwork elements (3a and 3b) is provided with aligned openings (4) at a desired location of the reactor wall (1), at which a framework or frame (5) is installed.

8. The method according to any one of the preceding claims 1 to 7, characterized in that the thickness of the finished reactor chamber (10) walls (W) is 30 to 50 cm.

9. The method according to any one of the preceding claims 1 to 8, characterized in that the outer wall formwork elements (3a), as well as the inner wall formwork elements 3b are provided with edge flanges or bends 3a', 3b'.

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