Batch slurry digester with secure sealing

Abstract

Batch slurry digester for recovering gas contained in slurry delivered by tractor and stored in a tank (21, 22) in a hole underground (S), comprising a liquid recovery circuit (12) and a gas recovery circuit (11), characterized in that the slurry storage tank (21, 22) is contained within a sealed liner (B) formed by the assembly of a lower liner (Bb) that conforms to the shape of the hole in the ground and an upper liner (Bh) that covers the lower liner (Bb), the upper and lower liners (Bb, Bh) by sealed liner joining means (28), the lower liner (Bb) being double-walled, and an inspection port (13) dug in the ground near the liner hole provides access to the space between the two layers of the lower liner (Bb) so as to potentially detect a liquid leak. Figure for the abstract: Fig. 2

Description

Title of the invention: Batch slurry digester with secure sealing

[0001] The present invention relates to a construction system for a batch slurry digester with secure sealing.

[0002] There are batch slurry digesters. These digesters have sealing defects which the present invention aims to correct.

[0003] The term "digester" refers to a facility for the methanation of slurry or manure. "Slurry process" refers to the treatment of effluents, manure, slurry, and plant residues directly from a livestock farm. "Discontinuous" refers to occasional discharge, typically on certain days of the week or month, from a telescopic handler or dump truck that has collected material from cleaning the livestock housing areas. The slurry digester aims to maximize the separation of liquids, gases, and solids constituting the slurry in order to optimize its recovery.

[0004] Prior art discontinuous slurry digesters offer a sealing achieved by the cooperation of a reinforced concrete shell following a hole dug in the ground, which cooperates with a tarpaulin which covers the shell.

[0005] A primary leakage defect stems from the concrete lining, which, due to aging and poor workmanship, can eventually develop cracks. The first problem with these cracks is that they are virtually undetectable, as they are hidden by slurry or dirt. The second problem is that they are costly to repair and cause significant operational downtime during the repair period. Furthermore, given the tractor's work within the lining, it is easy and common for an incorrect maneuver to damage the lining and compromise the seal. In short, the lining's watertightness is fragile, expensive, and difficult to identify. Finding a solution to this problem is urgent, especially since safety standards in this area are becoming more stringent and require traceability and reliability to ensure the quality and reliability of the seal.

[0006] A second leakage defect originates from the cover membrane, which can allow gas to leak. No fixed system currently exists for detecting leaks through the ceiling or at the junction between the ceiling and the tanking.

[0007] A principal object of the invention is therefore to propose a new solution for a batch slurry digester with secure sealing provided by both the tanking and the cover. The invention offers protection against liquid leakage and protection against gas leakage.

[0008] An object of the invention is to propose a solution that is demountable and easily adaptable.

[0009] One object of the invention is to propose a solution that is economical and easily industrializable.

[0010] One object of the invention is to provide a solution that withstands operating conditions involving the possibility of accidental impacts from the tractor bucket. The invention aims to withstand accidental impacts without requiring the solution to be shut down for safety inspection. In short, the installation must withstand normal tractor use and absorb minor imperfections in the farmer's driving.

[0011] In a principal aspect, the invention proposes to separate the sealing function, the tanking function, and the containment basin function. In a way, unlike the prior art which offers a solution by installing a concrete wall that simultaneously provides tanking, a containment basin, and sealing, the invention cleverly breaks down the functions and proposes here to mount a containment basin that can be assembled within a watertight liner that conforms to the tanking of a hole dug in the ground.

[0012] In one aspect the invention proposes a new liquid leak inspection function by means of a sight glass which cleverly cooperates with a double-walled tarpaulin.

[0013] In one aspect, the invention proposes a gas leak detection system by measuring and analyzing the deformation of the upper tarpaulin covering the material to be treated. The material to be treated is understood to mean effluents, manure, slurry, and other plant residues.

[0014] In one aspect, the invention provides assembly blocks for the wall and for the floor of the retention tank, so as to be able to assemble quickly and to be able to reuse the blocks or change the assembly blocks as the digester ages.

[0015] The invention will be better understood upon reading the accompanying figures, in which:

[0016] [Fig. 1] represents a longitudinal section of the production functions of a traditional digester

[0017] [Fig.2] represents a side section of a digester according to the invention

[0018] [Fig.3] represents a section of the double-walled waterproofing membrane

[0019] [Fig. 1] shows a longitudinal section of the production functions of a traditional digester (1) which, in a sealed tank (C) excavated in the ground (S) and covered with a high-profile cover (Bh), immerses the effluent, which releases gas (G) that is recovered by a gas recovery circuit (11). The effluent liquids are recovered at the bottom of the tank by a liquid recovery circuit (12). Traditionally, the tank (C) is made with a reinforced concrete floor and wall. An entrance is created with a slope allowing the tractor to drive into the tank. The following figure explains how this solution is improved.

[0020] [Fig. 2] shows a side view of a digester according to the invention. A hole dug in the ground (S) is clearly visible, with a watertight tank made of a liner (B) formed by assembling a lower liner (Bb), which conforms to the shape of the hole in the ground, and an upper liner (Bh). The watertight seal of the liners (28) between the lower liner (Bb) and the upper liner (Bh), which covers the lower liner (Bb), is made approximately at ground level (S). It is achieved by known means, which consist, for example, of inserting the two ends of the upper and lower liners into the same groove and then inflating an inflatable seal inside this groove, which presses each liner against the other and makes them watertight.

[0021] The digester includes in its lower part a liquid recovery circuit. (12) and, in the upper part, a gas recovery circuit (11). These two recovery circuits (11, 12) pass through the tank by means of sealed conduits. As described later, the seal is ensured in particular by the double-walled structure of the lower tank (Bb). Thus, an inspection chamber (13) dug into the ground near the tank opening provides access to the space between the two walls of the lower tank (Bb). In this way, if liquid were to leak from the lower tank (Bb), it would be accessible by inspecting the inspection chamber (13). This inspection could potentially be carried out automatically using sensors. It can, of course, also be done visually. The effluent retention tank (21, 22) is mounted inside the lower tank (Bb), following approximately the path of the lower tank (Bb) with a tank floor (22) made of modular assemblable plates (21) and tank walls (21) made of modular assemblable blocks.The tank walls therefore serve only to retain the slurry and to protect the lower tarpaulin (Bb) of the tractor. The tank walls do not provide a watertight seal.

[0022] The upper cover is fitted with a weighted sensor (100) that measures the cover's deformation and tension. This information is transmitted to a computer that verifies whether the regular evolution of the measurements corresponds to a normal operating regime or if a gas leak is suspected. In the latter case, an alarm is triggered to warn the digester operator of a possible gas leak. It should be noted that the upper cover sensor (Bh) is coupled to the leak-proof connection system (28) for the covers so as to accurately identify the openings and closings of the cover (B), which obviously modify the gas pressure inside the cover (B).

[0023] [Fig. 3] shows a detailed view of the sealing skin of the casing (1) which comprises two watertight walls (30a, 30b) with an inner wall (30a) and an outer wall (30b), the two walls (30a, 30b) are finely separated by a flexible mesh (31) which maintains a slight distance between them which allows them fit together but leave room for a small flow of liquid which will allow detection of any leak between the two walls (30a, 30b).

[0024] The present invention therefore relates to a batch slurry digester for recovering gas contained in slurry delivered by tractor and stored in a tank (21, 22) in a hole in the ground (S), comprising a liquid recovery circuit (12) and a gas recovery circuit (11), characterized in that the slurry storage tank (21, 22) is contained within a sealed liner (B) formed by the assembly of a lower liner (Bb) that conforms to the shape of the hole in the ground and an upper liner (Bh) that covers the lower liner (Bb), the upper and lower liners (Bb, Bh) by means of sealed liner joining means (28), the lower liner (Bb) being double-walled and an inspection port (13) dug in the ground near the liner hole provides access to the space between the two layers of the lower liner (Bb) so as to possibly detect a leak of liquid. .

[0025] The present invention therefore relates to a batch slurry digester characterized in that the tank floor (22) is made from modular assemblable plates (21) and the tank walls (21) are constructed from modular assemblable blocks.

[0026] The present invention therefore relates to a batch slurry digester characterized in that the upper cover (Bh) is equipped with a weighted deformation sensor (100) which allows the deformations of the upper cover (Bh) and the cover tension to be measured.

[0027] The present invention therefore relates to a discontinuous slurry digester characterized in that the information from the deformation sensor (100) is coupled with measurements taken on the sealed junction of the tanks (28) in order to distinguish tank opening events from those of voltage drop of the upper tank (Bh) by gas leakage.

[0028] It is understood that variants may be made to the description without departing from the scope of the protection conferred by this document.

Claims

Claims

1. Discontinuous pasty digester for recovering gas contained in slurry brought by tractor and stored in a tank (21, 22) in a hole under the ground (S) comprising a liquid recovery circuit (12) and a gas recovery circuit (11) characterized in that the slurry storage tank (21, 22) is contained a sealed tarpaulin (B) formed by the assembly of a low tarpaulin (Bb) which matches the shape of the hole in the ground and a high tarpaulin (Bh) which covers the low tarpaulin (Bb), the high and low tarpaulins (Bb, Bh) being assembled by means of sealed tarpaulin joining (28), the low tarpaulin (Bb) is double-skinned and a manhole (13) dug in the ground near the tarpaulin hole gives access to the space between the two skins of the low tarpaulin (Bb) so as to possibly detect a leak of liquid.

2. Discontinuous pasty digester according to claim 1 characterized in that the tank floor (22) is made from modular assemblable plates (21) and the tank walls (21) are constructed from modular assemblable blocks.

3. Discontinuous pasty digester according to claim 1 characterized in that the upper tank (Bh) is equipped with a weighted deformation sensor (100) which makes it possible to measure the deformations of the upper tank (Bh) and the tank tension to identify a possible gas leak.

4. Discontinuous pasty digester according to claims 1 and 3 characterized in that the information from the deformation sensor (100) is coupled to measurements taken on the sealed junction of tanks (28) in order to distinguish the events of tank opening from those of drop in voltage of the upper tank (Bh) due to gas leakage.

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