FR3066767A1 - SYSTEM AND METHOD FOR DISPLACING COVERAGE ON A METHANIZATION DIGESTER - Google Patents

Abstract

A displacement system (S) of a cover on a methanation digester (1), the system comprising: - at least a first longitudinal support (2) and a second longitudinal support (2 '), - a plurality of movable beams (3) whose ends are respectively guided on the first longitudinal support (2) and the second longitudinal support (2 ') along the axis of displacement (X), the movable beams (3) being interconnected and adapted to form a support surface of a cover (7), and - drive means (5) configured to connect to a main movable beam (3P) of said plurality of movable beams (3) so as to move it according to said displacement axis (X).

Description

SYSTEM AND METHOD FOR MOVING A COVER ON A METHANIZATION DIGESTER

GENERAL TECHNICAL AREA AND PRIOR ART

The present invention relates to the field of digesters used for anaerobic digestion both agricultural and industrial.

In a known manner, anaerobic digestion is a process of anaerobic degradation of organic matter in order to generate gas, in particular methane, which can then be used, for example, in a cogeneration plant to produce heating or electricity.

To carry out an anaerobic digestion by the dry route, it is known to use a digester in the form of a container of organic material, the upper surface of which is open and capable of being covered by a cover in order to form a storage enclosure for the gases generated.

In use, fresh organic matter is introduced into the digester and then the digester is sealed with a cover to form an enclosure in which the gases from the anaerobic degradation of the organic matter will be collected. Over time, the enclosure fills with gas and the blanket expands. Periodically, the digester must be opened to recover the old organic matter and replace it with fresh organic matter in order to start a new methanization cycle.

For an intermittent dry methanisation, several digesters are used sequentially to allow continuous use of the cogeneration plant. Also, in practice, every 15 days, a digester must be opened and closed. The opening and closing of a digester is binding on a farmer. Indeed, the cover has large dimensions and a heavy weight. In practice, an operator must manually pull the cover over the entire length of the digester to cover or uncover the digester, which is all the more painful since this operation must be carried out periodically as presented above.

An immediate solution would be for the farmer to use a traction device to manipulate the cover. However, given the dimensions and mass of the cover, the risk of damage to the cover by traction is high and this solution cannot be adopted.

In addition, to allow efficient anaerobic digestion, it is necessary for the operator to have liquid spray pipes and insulation panels in order to obtain optimal humidity and temperature conditions. Such operations increase the duration of commissioning of a digester following its supply of organic matter. In practice, these operations must be carried out by several operators, which forces them to postpone the completion of their daily tasks. These technical and practical constraints limit the development of anaerobic digestion using a discontinuous dry process despite these numerous economic and environmental advantages. The invention therefore aims to remedy these drawbacks by proposing a new system for moving a cover for an anaerobic digester which makes it easier to use on a daily basis.

GENERAL PRESENTATION OF THE INVENTION For this purpose, the invention relates to a system for moving a cover on a methanation digester, the system comprising: - at least a first longitudinal support and a second longitudinal support adapted to be fixed to side walls of a digester, the longitudinal supports being parallel along an axis of movement, - a plurality of mobile beams whose ends are respectively guided on the first longitudinal support and the second longitudinal support along the axis of movement, the mobile beams being connected together and adapted to form a support surface for a cover, and - drive means configured to connect to a main mobile beam of said plurality of mobile beams so as to move it along said axis of movement.

Thanks to the invention, a gas-tight cover can be placed directly on the mobile beams in order to be indirectly supported by the longitudinal supports. The displacement of a single mobile beam advantageously makes it possible to drive the other beams in displacement, which makes it possible to use drive means of simple and economical design.

A digester can be opened and closed quickly and conveniently, which is advantageous for methanization by discontinuous dry process. The hardship of the farmer is also greatly reduced.

In addition to supporting a gas-tight cover, such a displacement system allows the support of a layer of thermal insulation in order to maintain optimal temperature conditions in the digester.

Preferably, the mobile beams are connected by elementary links so as not to burden the displacement system. The use of traction straps is particularly advantageous because of its qualities of mechanical resistance and resistance to wear.

More preferably, the drive means comprise a first drive module and a second drive module adapted to connect to the ends of the main movable beam. A displacement of the main mobile beam by its ends makes it possible to avoid a crab displacement on the longitudinal supports, which improves the speed of movement and limits wear.

Preferably, each drive module is in the form of a cable reel. Such a drive module makes it possible to pull the main mobile beam remotely in both directions along the axis of movement X. In addition, a cable is simple to connect to a main mobile beam.

Preferably, the drive means are removable from the displacement system so as to be used in another digester equipped with mobile beams. The training resources are thus shared between several digesters, which saves money.

According to a preferred aspect, at least one mobile beam comprises a support member for a liquid sprinkler, preferably each mobile beam. Thus, the displacement system allows the displacement of a cover but also of a liquid sprinkler in order to humidify the organic matter. The sprinkler is precisely positioned when the cover is moved. It is no longer necessary for the operator to handle the sprinkler individually.

Preferably, at least one liquid sprinkler is connected to the support members of a plurality of mobile beams. Thus, the liquid sprinkler is kept high with the cover to moisten the organic matter. The sprinkler can thus fold in a practical way between the mobile beams in the open position.

Preferably, each end of a movable beam comprises a guide module, preferably comprising guide rollers. The friction is thus reduced to the maximum, which facilitates the movement of the mobile beams despite the weight of the cover and the equipment. The invention also relates to an assembly comprising: - a methanization digester, extending longitudinally along a displacement axis and comprising side walls, - a displacement system, as presented above, including the first longitudinal support and the second support longitudinal are respectively fixed to the side walls of the digester and - a cover arranged on movable beams of said displacement system.

Preferably, the assembly includes a layer of thermal insulation placed on mobile beams of said displacement system. The temperature conditions can thus be maintained in a practical manner.

Preferably, the assembly comprises at least one sprinkler supported by movable beams of said displacement system. Humidity conditions can thus be maintained in a practical way. The invention relates to a method of moving a cover on an anaerobic digester of an assembly as presented above, the method comprising a step of training the main movable beam by the drive means so as to move the mobile beams on the longitudinal supports along the axis of movement.

Such a displacement process makes it possible to close and open a digester in a practical and simple manner.

PRESENTATION OF THE FIGURES The invention will be better understood on reading the description which follows, given solely by way of example, and referring to the appended drawings in which: FIG. 1 is a schematic perspective representation of a digester of methanization equipped with a cover displacement system according to one embodiment of the invention, FIG. 2 is a diagrammatic representation from above of the digester of FIG. 1, FIG. 3 is a diagrammatic representation of a longitudinal support fixed to a side wall of a digester, FIG. 4 is a schematic representation of a fixing plate for the longitudinal support of FIG. 3, FIGS. 5 and 6 are schematic representations of a mobile beam, FIG. 7 is a view in side section of a digester in the open position, Figure 8 is a top view of a digester with deflection modules to allow opening erture of the digester, and Ια Figure 9 is a cross-sectional view at a mobile beam of the digester in the closed position.

It should be noted that the figures show the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary.

DESCRIPTION OF ONE OR MORE MODES OF IMPLEMENTATION AND IMPLEMENTATION The invention will be presented for a methanisation installation comprising a plurality of analog methanisation digesters 1 aligned consecutively as illustrated in FIG. 1. Such an installation is particularly suitable for methanization by dry discontinuous route during which the digesters 1 are used sequentially. Such an installation is known to those skilled in the art.

In this example, each digester 1 extends longitudinally along an axis X, hereinafter designated “displacement axis X”, which is oriented from rear to front as illustrated in FIGS. 1 and 2. Each digester 1 has a U-shape defining a rear wall 11 and two side walls 12 which are parallel, the digester 1 being open at the front to allow the passage of vehicles to move organic matter.

As illustrated in FIG. 1, the digester 1 is open from above and adapted to receive a sealing cover 7 in order to form a sealed enclosure for collecting the gas generated during anaerobic degradation. In known manner, the digester 1 comprises means for sealing the cover 7 tightly, in particular, a groove adapted to receive an inflatable tube. For example, the digester 1 is made of concrete and has a length of 20 m and a width of 8 m.

In practice, a rear edge 7B of the cover 7 is connected to the rear wall 11 of the methanization digester 1. To close the cover 7, the front edge 7A must be moved forward along the axis of movement X. reciprocally, to open the cover 7, its front edge 7A must be moved to the rear. Such a digester 1 is known to a person skilled in the art and will not be described in more detail.

According to the invention, with reference to Figures 1 and 2, the digester 1 is equipped with a displacement system S of a cover 7. In this embodiment, the displacement system S comprises a first longitudinal support 2 and a second longitudinal support 2 'adapted to be respectively fixed to the side walls 12 of the digester 1. The longitudinal supports 2, 2' are mutually parallel and extend parallel to the axis of movement X. The movement system S further comprises a plurality of mobile beams 3, the ends of which are respectively guided on the first longitudinal support 2 and the second longitudinal support 2 'along the axis of movement X, the mobile beams 3 being connected together and adapted to form a support surface for the cover 7. With reference to FIG. 2, the displacement system S further comprises drive means 5 configured to connect er to a main mobile beam 3P of said plurality of mobile beams 3 so as to move it along said axis of movement X.

In this embodiment, the two longitudinal supports 2, 2 ’are identical. Also, for the sake of clarity and conciseness, only the first longitudinal support 2 will now be described with reference to FIGS. 3 and 4.

The first longitudinal support 2 is made of a material adapted to resist the corrosion induced by contact with the gas, in particular, plastic or stainless steel while being able to support a high weight as will be detailed later . The first longitudinal support 2 comprises a longitudinal rail 20 connected to a plurality of fixing plates 21 spaced apart from one another along the rail 20. Each fixing plate 21 has holes so as to allow the passage of fixing screws and ensure thus securing the longitudinal rail 20 to a side wall 12 of the digester 1. Such a rail 20 makes it possible to guide the ends of the mobile beams 3 in a stable manner and to support the weight of the mobile beams 3, of the cover 7 and of any equipment. Each longitudinal support 2, 2 ’is sized according to the overall mass to be supported.

The longitudinal supports 2, 2 'preferably extend inside the digester 1 and are secured to the interior surfaces of the side walls 12 so as to allow a tight locking of the cover 7 in the traditional way, the longitudinal supports 2, 2 advantageously not increasing the overall size of a digester 1. Each fixing plate 21 makes it possible to move the rail 20 away from the side wall 12 in order to provide a passage for the means for guiding the mobile beams 3. Each support longitudinal 2, 2 'can be monobloc or modular.

In this embodiment, the mobile beams 3 are identical with the exception of the main mobile beam 3. Also, for the sake of clarity and conciseness, only a mobile beam 3 will now be described with reference to FIGS. 5 and 6.

Each movable beam 3 is made of a material adapted to resist the corrosion induced by contact with the gas, in particular, plastic or stainless steel. Each movable beam 3 comprises a main body 30 comprising at its ends guide devices 4 in order to cooperate with the rails 20 of the longitudinal supports 2, 2 ’. Each main mobile beam 3 thus extends perpendicular to the axis of displacement X along which the longitudinal supports 2, 2 ‘extend. The main body 30 has an upper surface 32 adapted to support the cover 7. Also, preferably, the upper surface 32 is planar.

In this example, with reference to FIG. 6, each guide device 4 comprises a plurality of guide rollers 41, 42, 43 adapted to cooperate with the guide rail 20 and thus facilitate movement with reduced friction. It goes without saying that the number of guide rollers 41, 42, 43 could be adapted as required.

More preferably still, with reference to FIG. 5, each mobile beam 3 comprises a plurality of support members 31 of a liquid sprinkler 8 (FIG. 9). Preferably, a sprinkler 8 is in the form of a flexible pipe, capable of conducting a liquid, which has a plurality of orifices in order to spray the organic matter and increase its humidity. In this example, the support members 31 are arranged in the lower part of the main body 30 so as not to be in contact with the cover 7. With reference to FIG. 5, each support member 31 is in the form of a cylindrical part into which a sprinkler 8 can be introduced. Preferably, each movable beam 3 comprises a plurality of support members 31 in order to support a plurality of sprinklers 8 concomitantly, preferably parallel to the axis X displacement. Preferably, the support members 31 are spaced along said body 30 so as to allow a uniform humidification.

As will be detailed later, the presence of support members 31 allows support for the sprinklers 8 directly with the displacement system S of the cover 7. In other words, the sprinklers 8 are deployed and stored concomitantly upon closure and when the cover 7 is opened, which reduces handling. As the sprinklers 8 are flexible, in particular of the fire hose type, they can advantageously be bent without constraint with the cover 7. In addition, the positioning of the sprinklers 8 is more precise, which improves the humidification of the organic matter. Longitudinal and parallel spray bars are thus formed.

The mobile beams 3 are connected to each other by connecting means so as to allow coordinated training of the mobile beams 3 following the movement of a single mobile beam 3

Referring to Figure 2, the connecting means are in the form of elementary links 35. Preferably, the elementary links 35 are flexible and are in the form of straps while having a reduced mass. In this example, four straps consecutively connect all of the mobile beams 3, but it goes without saying that their number could be different. With reference to FIG. 6, to allow the fixing of the elementary links 35, the movable beam 3 comprises fixing members 33 positioned on the upper surface 32 of the main body 30 of each main beam 3. In this example, each fixing member 33 is in the form of a flat fixing loop but it goes without saying that other types of fixing could be suitable. The elementary links 35 are fixed to the rear end of the digester 1.

According to a first aspect, the connecting means are in the form of a support veil connecting the mobile beams. Preferably, such a support veil is not gas tight. According to a preferred aspect, the connection means comprise elementary links 35 and a support veil fixed on the elementary links 35.

Advantageously, the mobile beams 3 connected together form, overall, a flat support surface for the cover 7. The cover 7 can thus rest on the mobile beams 3 and on the connecting means stably. The cover 7 can be easily moved by simple translation of the mobile beams 3 on the longitudinal supports 2, 2 ’as will be presented below.

In this example, the movable beam 3 located furthest forward is hereinafter designated "main mobile beam 3P" and is adapted to be driven by the drive means as will be presented below. To this end, with reference to Figure 2, the main movable beam 3P further comprises connecting members 36 to the drive means 5 which are in the form of rings allowing the connection of a carabiner. It goes without saying that other types of connection members 36 could be suitable. Since the mobile beams 3 are interconnected, the movement of one end beam makes it possible to cause the movement of all the other mobile beams 3.

Referring to FIG. 2, the displacement system S also comprises drive means 5 for the main movable beam 3P along the displacement axis X in order to allow the opening and closing of the cover 7.

Preferably, the drive means 5 comprise a first drive module 51 and a second drive module 52 adapted to connect respectively to the ends of the main movable beam 3P. In this example, each drive module 51, 52 is in the form of a cable reel, one end of which is equipped with a carabiner adapted to connect to a connection member 36 of the main movable beam 3P. The use of two drive modules 51, 52 facilitates the guiding of the main movable beam 3P and prevents the latter from moving in crab. However, it goes without saying that a single training module located in the center would be suitable.

The drive modules 51, 52 are adapted to exert traction on the main mobile beam 3P along the X axis directed towards the front. Such drive modules 51, 52 are advantageous for closing the cover 7. Preferably, each drive module 51, 52 comprises a motor, in particular an electric motor, in order to limit the hardship of farmers. Each drive module 51, 52 has a foot in order to exert traction on the main mobile beam 3P in the plane of the mobile beams 3, which limits friction.

Preferably, as shown in FIG. 2, the drive modules 51, 52 are placed close to the opening of the digester 1, that is to say, in front of the latter. The training modules 51, 52 are removably secured to the ground so that they can be moved from digester 1 to digester 1. It is therefore not necessary for a farmer to acquire training modules 51, 52 for each digester 1, which presents an economy linked to pooling.

According to one aspect of the invention, with reference to FIG. 8, the displacement system S further comprises two deflection modules 53, 54, in particular pulleys with angle gear, positioned behind the digester 1 or on the rear wall 11 of the digester 1 and adapted to respectively guide the cables of the drive modules 51, 52 in order to exert a traction along the axis X directed towards the rear. Such deflection modules 53, 54 are advantageous for moving the mobile beams 3 backwards and opening the cover 7.

The waterproof cover 7 of the digester 1 can be similar to the prior art and be made, for example, of PVC. The cover 7 has an area greater than that of the digester 1 so that it can be sealed in on the digester 1. Advantageously, it is not necessary for the farmer to acquire a particular cover 7. Preferably, the cover 7 is made of PVC, EPDM or the like. The cover 7 is able to swell during the generation of gas.

According to a preferred aspect of the invention, with reference to FIG. 9, an insulation layer 71 is positioned on the movable beams 3, under the waterproof cover 7, so as to limit the heat losses and maintain anaerobic degradation conditions optimal. Preferably, the insulating layer 71 is made of polyethylene and preferably has a thickness of 1 cm. The insulation layer 71 is linked or independent from the waterproof cover 7 and the support web. Preferably, the dimensions of the insulation layer 71 is less than that of the waterproof cover 7 since only the cover 7 is bordered on the digester 1. The addition of an insulation layer 71 increases the mass but this does not have any drawback since the movement system S makes it easier to move.

An example of the implementation of a method for closing a cover 7 on a methanization digester 1 comprising a displacement system S will now be presented. With reference to FIG. 7, the digester 1 is open and the cover 7 rests on the mobile beams 3 at the rear of said digester 1. The insulation layer 71 and the cover 7 are folded in an accordion or zigzag fashion and held by the beams mobiles 3 and elementary links 35 (not shown). The side edges of the cover 7 are folded inwards so as not to hinder its movement.

In this example, sprinklers 8 are positioned in the support members 31 of the mobile beams 3 and are also folded in accordion or zigzag. The farmer sets up the drive modules 51, 52 in front of the digester 1 and connects the cables of the drive modules 51, 52 to the main movable beam 3P and controls traction towards the front of the movable beam main 3P, preferably synchronized traction.

The main mobile beam 3P moves forward while being guided on the longitudinal supports 2, 2 ’. Due to the presence of the connecting means (elementary links 35 and / or support web) connecting the mobile beams 3, the mobile beams 3 are moved following the main mobile beam 3P so as to form a flat support surface on which rests the insulation layer 71 and the cover 7 as illustrated in Figure 2. In other words, the connecting means participate in the support of Ια waterproof cover 7. The sprinklers 8 are unfolded and extend longitudinally along the movement axis X. The farmer unfolds the lateral edges of the cover 7 and locks them in a sealed manner on the digester 1 so as to form a sealed enclosure. As illustrated in FIG. 9, the insulating layer 71 makes it possible to thermally insulate the sealed enclosure and the sprinklers 8 make it possible to guarantee an optimal humidity level.

Thanks to the displacement system S according to the invention, a cover 7 can be deployed in a practical and rapid manner. Advantageously, a cover 7, an insulation layer 71 and sprinklers 8 can be installed in one and the same step, which provides a significant saving of time. In addition, this displacement system S is compatible with the sealed locking means of the cover 7.

To open the digester 1 after having unlocked the cover 7 and folded down its lateral edges, the farmer need only use the deflection modules 53, 54 as illustrated in FIG. 8 in order to guide the cables of the drive modules 51, 52 so as to exert a traction directed towards the rear. During traction, the main movable beam 3P moves backwards and causes the cover 7, the insulation layer 71 and the sprinklers 8 to be folded. After opening, the farmer can access the interior from digester 1 to replace organic matter.

The displacement system S according to the invention allows easy use of a digester 1 without difficulty. Such a displacement system S can be implemented on a digester 1 already in service in order to benefit from the advantages of the invention, in particular, for a methanization by discontinuous dry process. A methanisation process has been presented in which the gas generated is stored in the digester under the cover, but it goes without saying that the invention applies to a digester comprising a tank dedicated to the storage of the gases generated. The invention has been presented for a methanation digester in the agricultural field but it applies to any methanization digester, in particular, for an industrial composting platform.

Claims (10)

1. Displacement system (S) of a cover (7) on a methanization digester (1), the system comprising: at least a first longitudinal support (2) and a second longitudinal support (2 ') adapted to be fixed side walls (12) of a digester (1), the longitudinal supports (2,2 ') being parallel along an axis of movement (X), a plurality of mobile beams (3) whose ends are respectively guided on the first longitudinal support (2) and the second longitudinal support (2 ') along the axis of movement (X), the movable beams (3) being interconnected and adapted to form a support surface for a cover (7 ), and drive means (5) configured to connect to a main mobile beam (3P) of said plurality of mobile beams (3) so as to move it along said axis of movement (X). 2. System according to claim 1, wherein the movable beams (3) are connected by elementary links (35). 3. System according to one of claims 1 to 2, wherein the drive means (5) comprise a first drive module (51) and a second drive module (52) adapted to connect to the ends of the main mobile beam (3P). 4. The system of claim 3, wherein each drive module (51,52) is in the form of a cable reel. 5. System according to one of claims 1 to 4, wherein at least one movable beam (3) comprises a support member (31) of a liquid sprinkler (8), preferably each movable beam (3). 6. System according to one of claims 1 to 5, wherein at least one liquid sprinkler (8) is connected to the support members (31) of a plurality of movable beams (3). 7. System according to one of claims 1 to 6, wherein each end of a movable beam (3) comprises a guide module (4), preferably comprising guide rollers (41,42, 43). 8. An assembly comprising: a methanation digester (1), extending longitudinally along a displacement axis (X) and comprising side walls (12), a displacement system (S) according to one of the preceding claims, the first longitudinal support (2) and the second longitudinal support (2 ') are respectively fixed to the side walls (12) of the digester (1) and a cover (7) arranged on mobile beams (3) of said displacement system (S) . 9. An assembly according to the preceding claim, comprising a thermal insulation layer (71) disposed on movable beams (3) of said displacement system (S). 10. A method of moving a cover (7) on an anaerobic digester (1) of an assembly according to one of claims 8 to 9, the method comprising: a step of driving the main mobile beam (3P ) by the drive means (5) so as to move the mobile beams (3) on the longitudinal supports (2, 2 ') along the axis of movement (X).