Input pretreatment tank, installation and associated process

Abstract

The invention relates to a tank (1) comprising an inclined bottom wall (2) and a side wall (3) defining an internal space (4), the tank having an inclined conveyor device (6) for extracting from the tank the non-methanizable materials that settle at the bottom of the tank, the conveyor device being located at the bottom wall between a lower end of the bottom wall and an upper end of the bottom wall, the conveyor device having a lower end located opposite a hatch (15) formed in the side wall, the tank having a discharge device (14) positioned at a distance from the bottom wall, the discharge device comprising a water reservoir and is configured to discharge a quantity of water onto the bottom wall in order to carry away the non-methanizable materials that settle at the bottom of the tank. Figure for the abstract: 1

Description

Title of the invention: Input pretreatment tank, associated installation and method Technical field

[0001] The invention relates to the field of methanization systems. More particularly, the invention relates to an input pretreatment tank. Technological background

[0002] Methanization is a known process that has been used for many years. The objective of methanization is to convert organic matter into biogas. However, the success of this process relies mainly on the ability to efficiently isolate methanizable organic matter from non-methanizable matter and on the ability to defiber, grind, make bio-accessible the organic matter and homogenize this methanizable organic matter in the biologically active digestate by increasing the contact areas. The streams of raw materials from various sources such as agricultural waste, food residues and sewage sludge increase the difficulty of this separation.

[0003] Known methanization installations comprise a pretreatment tank located upstream of the anaerobic digester.

[0004] However, the known tanks have the particular disadvantage of not being able to process a large flow rate of inputs comprising solid elements.

[0005] Furthermore, because non-methanizable materials sediment at the bottom of the tank, the intervention of an agent is regularly necessary in known tanks in order to evacuate unwanted solid non-methanizable materials. Such an intervention is long and can prove dangerous for the agent who must lift heavy loads and breathe gases which can prove toxic.

[0006] Thus, there is a need to improve methanization systems and in particular pretreatment tanks. Summary of the invention

[0007] An idea behind the invention is to solve the above-mentioned problems.

[0008] Another idea underlying the invention is to obtain an input pretreatment tank capable of receiving and treating a large flow of inputs.

[0009] Another idea underlying the invention is to obtain an automated pretreatment tank.

[0010] Another idea underlying the invention is to facilitate the evacuation of non-methanizable solid materials.

[0011] The term “pretreatment” is defined according to the invention as being the preparation methanizable materials in the pretreatment tank before transferring them to an anaerobic digester. Pretreatment includes, for example, the separation of non-methanizable materials from methanizable materials, the homogenization of methanizable materials and the grinding of methanizable materials.

[0012] It is important to note that non-methanizable materials can have a negative impact on the methanization process. The negative consequences of non-methanizable materials include reducing the useful volume of the anaerobic digester, blocking and damaging the various equipment such as the piping, pump, grinder, agitator, etc. Therefore, it is crucial to sort and prepare the inputs entering a methanization system to ensure that the appropriate and biodegradable materials are introduced, while limiting the introduction of non-methanizable materials as much as possible.

[0013] The term “inputs” is defined according to the invention as being materials poured into the pretreatment tank. The inputs may comprise solid materials and / or liquid materials. They may comprise several types of materials including methanizable materials and non-methanizable materials.

[0014] Methanizable materials include, for example: agricultural waste such as crop residues, straw, manure, slurry, fibers, food waste, sludge, green waste and certain industrial effluents.

[0015] Non-methanizable materials include, for example: inorganic materials, such as pebbles, metals, plastics, strings, construction materials (concrete blocks), certain non-methanizable materials such as pieces of wood and certain industrial residues.

[0016] According to one embodiment, the invention provides an input pretreatment tank, said tank comprising an inclined bottom wall and a side wall extending from the bottom wall, the bottom wall and the side wall defining an internal space intended to receive the inputs, the tank comprising an inclined conveyor device for extracting from the tank the non-methanizable materials which sediment at the bottom of the tank, the conveyor device being located at the bottom wall between a lower end of the bottom wall and a high end of the bottom wall, the conveyor device having a lower end located opposite a trapdoor provided in the side wall, the tank comprising a discharge device positioned at a distance from the bottom wall,the discharge device comprises a reservoir intended to receive water and is configured to pour a quantity of water onto the bottom wall in order to carry away the non-methanizable materials which sediment at the bottom of the tank.

[0017] Thanks to these characteristics, it is possible to effectively clean the bottom of the pretreatment tank by evacuating the non-methanizable materials that have sedimented at the bottom of the tank. Indeed, the inclination of the bottom wall facilitates the movement of the non-methanizable materials in the direction of the inclination, notably via gravity. The discharge device, whose water tank has been previously filled with water, allows a large quantity of water to be poured onto the inclined bottom wall and act in synergy to effectively evacuate the sediments that have precipitated at the bottom of the tank through the trapdoor. The reservoir of the discharge device allows specific control of the quantity of water that will be poured into the tank.

[0018] According to embodiments, such a tank may comprise one or more of the following characteristics.

[0019] According to one embodiment, the tank comprises a ceiling wall which extends from an upper end of the side wall.

[0020] According to one embodiment, the ceiling wall comprises at least one through opening through which the internal space of the tank is accessible.

[0021] According to embodiments, the dumping device is attached to the side wall.

[0022] According to embodiments, the tank of the discharge device has a capacity of 200 liters per linear meter. According to one embodiment, the length of the tank of the discharge device is between 3 and 4 meters. For example, the length of the tank is 3.5 meters with a capacity of 700 liters.

[0023] According to one embodiment, the pouring device comprises a pivot allowing the tank to tilt and the water to be poured.

[0024] According to one embodiment, the dumping device is a tipping bucket.

[0025] According to one embodiment, the discharge device is located at a upper portion of the side wall, the upper portion of the side wall being spaced from the bottom wall.

[0026] Thus, the water poured by the discharge device accumulates significant kinetic energy and the cleaning of the sediments located at the bottom of the tank is improved.

[0027] According to one embodiment, the discharge device is located above an upper end of the side wall. According to one embodiment, the discharge device is located opposite the through opening of the ceiling wall.

[0028] According to one embodiment, the discharge device is located directly above the upper end of the bottom wall.

[0029] Thus, the water poured from the discharge device effectively covers the entire internal surface of the bottom wall with a force to direct the sediment through the trapdoor in the open position.

[0030] According to one embodiment, the discharge device is fixed against the ceiling wall.

[0031] According to one embodiment, the tank comprises a plurality of discharge devices.

[0032] According to one embodiment, the tank comprises a water inlet conduit opening into the reservoir of the discharge device.

[0033] According to one embodiment, the tank comprises a control unit.

[0034] According to one embodiment, the tank comprises a control unit configured to trigger the actuation of the conveyor device when the inputs are added into the internal space of the tank.

[0035] According to one embodiment, the tank comprises a control unit configured to trigger the opening of the hatch and at least one tilting of the pouring device when the liquid level in the internal space is below a threshold.

[0036] According to one embodiment, the control unit is configured to activate the filling of the tank with water via the water inlet conduit, before triggering the tilting of the tank from the pouring device.

[0037] According to one embodiment, the control unit is configured to perform cleaning cycles, a cleaning cycle comprising filling the water tank with a determined quantity of water, and tilting the tank containing the water in order to pour the water into the internal space of the tank.

[0038] According to one embodiment, the control unit is configured to automatically perform between 1 and 10 consecutive cleaning cycles.

[0039] According to one embodiment, when 100% represents the tank being fully filled, the threshold is a liquid level chosen from a range between 1% and 20%, preferably between 1 and 10%, for example the threshold is 5%, 2% or 1%.

[0040] According to one embodiment, the inclined bottom wall has a slope of between 4% and 30%. According to a preferred embodiment, the slope is between 10% and 25%, even more preferably approximately 20%.

[0041] According to one embodiment, the slope has a slope break line increasing the slope between the slope break line and the lower end of the bottom wall.

[0042] According to one embodiment, the bottom wall is further inclined so as to direct the non-methanizable materials sedimenting at the bottom of the tank towards the conveyor device.

[0043] According to one embodiment, the side wall comprises an extraction orifice located opposite the hatch, the extraction orifice being crossed by an upper end of the conveyor device, the conveyor device being configured to convey the non-methanizable materials which sediment at the bottom of the tank through the extraction orifice in order to extract them from the tank.

[0044] According to one embodiment, the bottom wall comprises a gutter in which the conveyor device is housed.

[0045] According to one embodiment, the gutter connects the hatch to the extraction orifice.

[0046] According to one embodiment, the gutter has a slightly greater width to the width of the conveyor device. According to one embodiment, the width of the gutter is equal to the width of the conveyor device increased by a distance of between 0.5 cm and 10 cm, preferably between 1 cm and 5 cm.

[0047] According to one embodiment, the gutter has a height similar to the height of the conveyor device. According to one embodiment, the height of the gutter is equal to the height of the conveyor device increased by a distance of between 0.5 cm and 10 cm, preferably between 1 cm and 5 cm.

[0048] According to one embodiment, the length of the gutter is less than the length of the conveyor device.

[0049] According to one embodiment, the internal space of the tank comprises an agitator comprising a vertical shaft. The agitator makes it possible to mix the inputs present in the internal space of the tank, and to direct the non-methanizable materials sedimenting at the bottom of the tank towards the conveyor device.

[0050] According to one embodiment, the internal space of the tank comprises an agitator comprising a shaft having an angle of between 80° and 100° with the ceiling wall.

[0051] According to one embodiment, the agitator is a vertical propeller agitator. According to one embodiment, the propellers extend radially from the agitator shaft.

[0052] According to one embodiment, the internal space of the tank comprises an agitator comprising a shaft having an angle of between 80° and 100° with the side wall. According to one embodiment, the agitator is a horizontal propeller agitator.

[0053] According to one embodiment, the tank comprises a plurality of agitators. According to one embodiment, the tank comprises 2, 3 or 4 agitators.

[0054] According to one embodiment, the plurality of agitators comprises an agitator comprising a shaft having an angle of between 80° and 100° with the ceiling wall and an agitator comprising a shaft having an angle of between 80° and 100° with the side wall.

[0055] According to one embodiment, the internal space of the tank comprises a grinding pump configured to pump and grind the inputs, the tank further comprises a piping system configured to recirculate the ground inputs in the internal space of the tank or configured to transfer the ground inputs to an anaerobic digester. The grinding pump has the advantage of allowing control of the grinding particle size, which increases the exchange surface between the organic matter and the bacterial flora. Thus, when the ground mixture is integrated into an anaerobic digester to produce biogas, productivity is increased.

[0056] According to one embodiment, the grinder pump is positioned on the slope break line.

[0057] According to one embodiment, the grinder pump is positioned at the lower end of the bottom wall.

[0058] According to one embodiment, the conveyor device is chosen from belt conveyors and screw conveyors.

[0059] According to a preferred embodiment, the conveyor device comprises a worm screw, preferably without a core.

[0060] According to a preferred embodiment, the tank has the general shape of a circular cylinder.

[0061] According to one embodiment, the tank has an internal volume of between 20 m3 and 200 m3, preferably a volume of between 40 m3 and 90 m3, for example 50 m3 or 80 m3.

[0062] According to one embodiment, the tank comprises a piping system.

[0063] According to one embodiment, the piping system comprises at least one conduit input inlet, preferably two input inlet conduits.

[0064] According to one embodiment, a first input inlet conduit is intended to incorporate thicker and / or more solid inputs than a second input inlet conduit which is intended to incorporate inputs having a lower viscosity.

[0065] According to one embodiment, the at least one input inlet conduit opens into the internal space of the tank, at the level of an upper part of the side wall.

[0066] According to one embodiment, the piping system comprises at least one water inlet conduit.

[0067] According to one embodiment, the piping system comprises at least one recirculation conduit intended to circulate the mixture in the internal space of the tank.

[0068] According to one embodiment, the recirculation conduit is associated with the grinder pump.

[0069] According to one embodiment, the invention also provides an installation for anaerobic digestion of inputs comprising: - an input pretreatment tank as mentioned above, the tank comprising an input inlet conduit and an outlet conduit, - an anaerobic digester connected to the tank by the outlet pipe, the outlet pipe being capable of supplying the anaerobic digester with methanizable materials.

[0070] According to one embodiment, the anaerobic digester comprises a recirculation conduit connecting the internal space of the pretreatment tank, the recirculation conduit being capable of incorporating part of the contents present in the digester into the internal space of the pretreatment tank.

[0071] According to one embodiment, the invention also provides an anaerobic digestion method, the method comprising the following steps: - introduce inputs into an aforementioned input pretreatment tank, the inputs comprising non-methanizable materials and methanizable materials; - extract non-methanizable materials from the input pretreatment tank via the conveyor device and / or the hatch provided in the side wall; and - introduce the methanizable materials into an anaerobic digester from the input pretreatment tank.

[0072] According to one embodiment of the method, it comprises the following steps: - incorporate, via a recirculation conduit connecting the internal space of the pretreatment tank to the anaerobic digester, part of the contents present in the anaerobic digester in order to seed the mixture present in the tank and to prepare it for anaerobic digestion upstream of the anaerobic digester; then - introduce the seeded mixture into the anaerobic digester.

[0073] According to one embodiment of the method, the seeded mixture remains in the tank for 10 to 60 minutes, and preferably for approximately 30 minutes.

[0074] According to one embodiment of the method, the flow rate for filling and emptying the tank is between 40 m3 and 200 m3.

[0075] According to one embodiment, the invention also provides a use of the aforementioned installation for implementing the aforementioned method. Brief description of the figures

[0076] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings.

[0077] [Fig.l] represents a schematic view, in section, of an input pretreatment tank according to a first embodiment.

[0078] [Fig.2] represents a perspective view, according to a first orientation, of a pretreatment tank according to a second embodiment.

[0079] [Fig.3] represents a perspective view, according to a second orientation of the tank pretreatment, according to the second embodiment.

[0080] [Fig.4] represents a functional diagram of an installation intended for digestion anaerobic methanizable materials. Description of the embodiments

[0081] By convention, the terms "external" and "internal" are used to define the relative position of one element with respect to another, with reference to the inside and outside of the tank. The terms "top" and "bottom" are used to define the relative position of one element in relation to another, with reference to the normal operating position of the pretreatment tank.

[0082] A tank 1 for pre-treatment of inputs is described with [Fig.l].

[0083] The input pretreatment tank 1 comprises a bottom wall 2, a side wall 3 surrounding the bottom wall 2, and a ceiling wall 5 extending from an upper end of the side wall 3 to form an internal space 4 of the tank 1. The internal space 4 of the tank 1 comprises a mixture of non-methanizable materials 11 and methanizable materials, which may be liquid and / or solid.

[0084] The ceiling wall 5 does not hermetically close the internal space 4.

[0085] The external surface 21 of the bottom wall 2 is flat and rests against a support (not shown in [Fig.l]), such as the ground or foundations. The internal surface 22 of the bottom wall 2 is inclined with a constant slope of approximately 20%.

[0086] The tank 1 comprises a conveyor device 6 of the endless screw type which is intended to extract from the tank 1 the non-methanizable materials which fall to the bottom of the tank 1, such as stones, scrap metal, etc., which are not decomposable via a methanizer. The size of the non-methanizable materials evacuated from the tank 1 is variable, the size usually between 0.5 cm and 10 cm.

[0087] The endless screw without core 6 extends from a lower end of the internal surface 22 towards an upper end of the internal surface 22, flush with the internal surface 22 of the bottom wall 2 in order to convey towards the outside of the tank 1 the non-methanizable materials which have settled at the bottom of the tank 1. The upper end of the endless screw 6 passes through an extraction orifice 7 which is arranged in the side wall 3 and which opens outside of the tank 1.

[0088] The coreless worm screw 6 is configured to automatically convey the non-methanizable materials towards the extraction orifice 7 continuously, that is to say that the non-methanizable materials are conveyed from bottom to top via the coreless worm screw 6 and are discharged outside the tank 1.

[0089] The non-methanizable materials removed from the tank 1 are received in a reservoir 8 located outside the tank, below the extraction orifice 7, directly above the upper end of the endless screw without core 6.

[0090] The tank 1 further comprises a vertical pendulum agitator 9 with propellers in order to allow effective agitation of the inputs with a liquid such as water. Such an agitator allows effective agitation while being compact.

[0091] The inputs are added to the tank 1 via an input inlet conduit 10 passing through an upper part of the side wall 3, close to the ceiling wall 5.

[0092] When the inputs are added to the tank 1, they are mixed with an aqueous mixture which may consist of water or which may include water and liquid methanizable materials, for example slurry and digestate from the anaerobic digester, in order to form a heterogeneous mixture 11 comprising methanizable materials and non-methanizable materials. The non-methanizable materials which have a higher density than water move towards the internal surface 22 of the bottom wall 2 of the tank 1 and therefore move towards the conveyor device 6 which automatically conveys said dense non-methanizable materials towards the outside of the tank 1. The main non-methanizable materials which are extracted from the tank 1 are inorganic materials such as pebbles, sand, scrap metal.

[0093] The tank further comprises a grinder pump 12 positioned on the internal surface 22 and piping 13 connected to the grinder pump in order to: - crushing elements of the heterogeneous mixture 11 and transferring them back into the internal space 4 of the tank 1, or - transfer the crushed mixture to an anaerobic digester.

[0094] The pretreatment tank 1 further comprises a water discharge device 14 which is a tilting bucket fixed against the side wall 3 and a water inlet conduit (not shown in [Fig.l]) for filling the water reservoir of the tilting bucket 14.

[0095] The discharge device is arranged in the internal space 4, directly above the lower end of the internal surface 22, at a height sufficient to remain at a distance from the heterogeneous mixture 11 during operation of the tank 1.

[0096] The tank 1 further comprises a hatch 15 located in the lower part of the side wall 3, close to the lower end of the internal surface 22.

[0097] When the tank 1 is empty or almost empty, the elements having sedimented at the bottom of the tank which have not been extracted by the conveyor device 6 are evacuated through the trapdoor 15 which is in the open position via the triggering of the tilting bucket 14 in order to direct the sediments towards a receptacle 16 located outside the tank 1.

[0098] The tipping bucket 14 comprises a reservoir for storing water and a trigger such as an electromagnetic contactor for controlling the discharge of water into the internal space 4 of the tank 1.

[0099] The tipping bucket 14 is for example configured for automatic discharge, that is to say that when the liquid level in the tipping bucket is higher than a threshold, the tipping bucket 14 tips and pours the water towards the bottom of the tank 1. The flow rate of water poured into the tipping bucket and the frequency of filling of the tipping bucket can be configured via a control unit.

[0100] Water is poured into the internal space 4 of the tank 1 from a certain height, for example from a height of 4 meters, it therefore acquires kinetic energy. Consequently, the water will strike the internal surface 22 of the bottom wall 2 and the elements having sedimented at the bottom of the tank 1 by applying a force there which will create turbulence. The quantity of water poured is chosen so that the entire bottom surface 22 is covered with water. The tipping bucket has for example a length of 3.5 meters with a tank capacity of 700 liters.

[0101] Consequently, from this overflow and from the internal surface 22 which is inclined towards the trapdoor 15, the moving water will lift, transport and move the non-methanizable materials placed at the bottom of the tank 1 towards the trapdoor 15 which has been previously opened in order to evacuate them towards the receptacle 16. The receptacle 16 is for example a recovery basin.

[0102] The tipping bucket 14 is connected to a control unit programmed to discharge a quantity of water periodically, for example once after each emptying of the tank 1, that is to say after the removal of the majority of the liquid present in the internal space 4 of the tank 1, for example when the tank 1 no longer contains or has almost no more liquid.

[0103] The tank 1 has, for example, the shape of a circular cylinder with a diameter of between 5 and 7 meters and a height of between 4 and 5 meters.

[0104] In relation to Figures 2 to 3, a second embodiment of a pretreatment tank is described below.

[0105] Identical or similar elements bear the same reference numbers incremented by 100.

[0106] The tank 101 differs from the tank 1 in that the slope of the internal surface 122 includes a slope break line 123 increasing the slope between the slope break line and the lower end of the internal surface 122. The grinder pump 112 is positioned at the slope break line 123.

[0107] The inner surface 122 of the bottom wall 22 comprises a gutter 140 extending between the hatch 115 and the extraction orifice 107. The conveyor device 106 is housed in the gutter 140. The upper end of the conveyor device 106 is located above the tank 108 which has a screen 118. The screen 118 is intended to receive large solid non-methanizable materials and the tank 108 is intended to collect residual water which has been extracted from the tank with the solid non-methanizable materials. The tank 108 may comprise a recirculation conduit intended to transfer the residual water from the tank 108 to the internal space 104 of the tank 101.

[0108] The tipping bucket 114 is fixed above the side wall 103, directly above the upper end of the internal surface 122. The tipping bucket 114 is positioned so as to face the hatch 115 so that the water poured via the tipping bucket carries the sediments into the receptacle 116 located outside the tank 101. The hatch 115 comprises, for example, a wall valve configured to move from a closed position in which the non-methanizable materials do not pass through the hatch 115 to an open position allowing the non-methanizable materials to pass so that they pour into the receptacle 116.

[0109] The tank 101 comprises a piping system comprising in particular the following elements: - a water inlet pipe 130 intended to fill the reservoir of the tipping bucket 114. The water inlet pipe 130 opens into the reservoir of the tipping bucket 114. - A second water inlet conduit 131 intended to supply the internal space 104 of the tank 101. The second water inlet conduit 131 passes through an upper part of the side wall 103. - An input inlet duct 110 intended to incorporate the inputs into the internal space 104 of the tank 101. The input inlet duct 110 passes through an upper part of the side wall 103. - A recirculation conduit 113 intended to recirculate the crushed inputs in the internal space 104. The recirculation conduit 113 comprises a first portion which is connected to the crusher pump 112 and which passes through the side wall 103 and a second portion allowing the conveyance and discharge of the crushed inputs into the internal space 104 of the tank 101. The discharge orifice 133 of the recirculation conduit 113 is positioned close to the ceiling wall 105 in order to discharge the crushed inputs from the top of the tank 101.

[0110] The tank 101 comprises a plurality of standard equipment such as safety barriers, access devices, valves, control systems, alarm systems, etc.

[0111] In relation to [Fig.4], an installation for anaerobic digestion of non-methanizable materials is described below.

[0112] The installation 70 comprises an input reception zone 71, a pretreatment tank 201 and an anaerobic digester 72. The pretreatment tank 201 is one of the pretreatment tanks as mentioned above, for example the pretreatment tank 1 or the pretreatment tank 101.

[0113] The input receiving area 71 comprises a hopper opening into a receiving bin which comprises a crusher in order to reduce the large solid inputs into smaller solid inputs. A conveyor is positioned between the receiving bin and the tank 201 in order to transport the inputs into the internal space of the tank 201 via an input inlet conduit in order to pre-treat the inputs to introduce the methanizable materials via a conduit into the anaerobic digester 72.

[0114] The pretreatment carried out in tank 201 comprises the following steps: - add the inputs comprising non-methanizable materials and methanizable materials and water into the internal space of the tank 201, preferably with a high input flow rate, for example a flow rate of 19 tonnes of inputs per hour, in order to to form a heterogeneous mixture; - continuously and automatically extract the non-methanizable materials which sediment at the bottom of the pretreatment tank 201, via the conveyor device, - mix via the agitator and / or the grinding pump by recirculating the ground inputs in the internal space of the tank 201, - introduce the mixture into the anaerobic digester 72 from tank 201; - clean the bottom of the tank 201 via a tilting bucket configured to be automatically triggered with opening of the hatch to allow the evacuation of non-methanizable materials to the receptacle, located outside the tank 201.

[0115] Such a method is preferably automated in order to limit as much as possible the interventions of agents which could be dangerous and slow down production capacity.

[0116] According to an alternative embodiment of the method when the anaerobic digester is in operation, the pretreatment method comprises the additional steps indicated below: - incorporate via a conduit a portion of the contents present in the anaerobic digester 72 in order to seed the mixture present in the tank 201 in order to prepare it for anaerobic digestion before they are introduced into the anaerobic digester 72; then - introduce the seeded mixture into the anaerobic digester 72.

[0117] Thanks to such a process, the rate of degradation of the substrates in the anaerobic digester is increased.

[0118] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0119] Some of the elements, in particular the components of the control unit, can be implemented in different forms, in a unitary or distributed manner, by means of hardware and / or software components. Usable hardware components are specific integrated circuits ASIC, programmable logic networks FPGA or microprocessors. Software components can be written in different programming languages, for example C, C++, Java or VHDL. This list is not exhaustive.

[0120] The use of the verb “comporter”, “comprendre” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0121] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. A tank for pre-treating inputs, said tank (1, 101, 201) comprising an inclined bottom wall (2, 102) and a side wall (3, 103) extending from the bottom wall, the bottom wall and the side wall defining an internal space (4, 104) intended to receive the inputs, the tank comprising an inclined conveyor device (6, 106) for extracting from the tank the non-methanizable materials which sediment at the bottom of the tank, the conveyor device being located at the bottom wall between a lower end of the bottom wall and a higher end of the bottom wall, the conveyor device having a lower end located opposite a trapdoor (15, 115) formed in the side wall, the tank comprising a discharge device (14, 114) positioned at a distance from the bottom wall,the discharge device comprises a reservoir intended to receive water and is configured to pour a quantity of water onto the bottom wall in order to carry away the non-methanizable materials which sediment at the bottom of the tank.,

2. A tank according to claim 1, wherein the pouring device (14, 114) is a tipping bucket.

3. A tank according to claim 1 or 2, wherein the discharge device is located at an upper portion of the side wall, the upper portion of the side wall being spaced from the bottom wall.

4. A tank according to any one of claims 1 to 3, wherein the pouring device is located above an upper end of the side wall.

5. Tank according to one of claims 1 to 4, in which the pouring device (114) is located directly above the upper end of the bottom wall (103).

6. Tank according to one of claims 1 to 5, the tank comprising a control unit configured to trigger the actuation of the conveyor device when the inputs are added into the internal space of the tank.

7. Tank according to one of claims 1 to 6, the tank comprising a control unit configured to trigger the opening of the hatch and at least one tilting of the pouring device when the liquid level in the internal space is below a threshold.

8. Tank according to one of claims 1 to 7, in which the inclined bottom wall has a slope of between 4% and 30%.

9. Tank according to one of claims 1 to 8, in which the side wall comprises an extraction orifice (7, 107) located opposite the hatch, the extraction orifice being crossed by an upper end of the conveyor device, the conveyor device being configured to convey the inputs which sediment at the bottom of the tank through the extraction orifice in order to extract them from the tank.

10. Tank according to one of claims 1 to 9, in which the bottom wall comprises a gutter (140) in which the conveyor device (106) is housed.

11. Tank according to one of claims 1 to 10, in which the internal space of the tank comprises an agitator comprising a vertical shaft.

12. A tank according to one of claims 1 to 11, wherein the internal space of the tank comprises a grinding pump (12, 112) configured to pump and grind the inputs, the tank further comprises a piping system (13, 113) configured to recirculate the ground inputs in the internal space of the tank or configured to transfer the ground inputs to an anaerobic digester (72).

13. Tank according to one of claims 1 to 12, in which the conveyor device comprises an endless screw.

14. Installation (70) for anaerobic digestion of inputs comprising: - an input pretreatment tank (1, 101, 201) according to one of claims 1 to 13, the tank comprising an input inlet conduit (10, 110) and an outlet conduit, - an anaerobic digester (72) connected to the tank by the outlet conduit, the outlet conduit being capable of supplying the anaerobic digester with methanizable materials.

15. A method of anaerobic digestion, the method comprising the following steps: - introducing inputs into an input pretreatment tank (1, 101, 201) according to one of claims 1 to 13, the inputs comprising non-methanizable materials and methanizable materials; - extracting the non-methanizable materials from the input pretreatment tank by the conveyor device and / or the trapdoor provided in the side wall; and - introducing the methanizable materials into an anaerobic digester (72) from the input pretreatment tank.

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