FR3055329A1 - PROCESS FOR CONSTRUCTING A BOREED TANK, IN PARTICULAR A DIGESTER, AND A BIOGAS PRODUCTION PLANT INCLUDING THE DIGESTER - Google Patents

Abstract

The method comprises the steps of: - arranging an excavation; - create a cavity in this excavation; placing an outer membrane in this cavity and placing an inner membrane inside said outer membrane; - fill with liquid the volume delimited by the internal membrane; pouring liquid concrete between the outer membrane and the inner membrane to substantially the mid-height of said internal membrane filled with liquid, so as to obtain an uplift of this inner membrane and of this liquid with respect to the outer membrane, to a position of equilibrium; Waiting for the time required for setting the concrete beyond the plastic phase of this concrete. - complete the pouring of liquid concrete. The installation includes the buried tank (17) and comprises a house (1), a pipe (10) for discharging wastewater from the house to the tank (17), a tank (4) for recovering the biogas produced in the digester (2), and a conduit (15) for conveying this biogas towards the dwelling (1).

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

055 329

58016

COURBEVOIE © IntCI ⁸ : C 02 F11 / 04 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 08.29.16. © Applicant (s): PÛMES DARRE CONSTRUCTION (© Priority: Limited liability company - FR. @ Inventor (s): DARRE BENOIT. ©) Date of public availability of the request: 02.03.18 Bulletin 18/09. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): POMES DARRE CONSTRUCTION related: Limited liability company. ©) Extension request (s): (© Agent (s): LLR.

METHOD FOR CONSTRUCTING AN UNDERGROUND TANK, PARTICULARLY A DIGESTER, AND BIOGAS PRODUCTION INSTALLATION INCLUDING THIS DIGESTER.

FR 3 055 329 - A1

The method includes the steps of:

- construct an excavation;

- create a cavity in this excavation;

- Place an outer membrane in this cavity and place an inner membrane inside said outer membrane;

- fill the volume delimited by the internal membrane with liquid;

pouring liquid concrete between the outer membrane and the inner membrane to substantially half the height of said inner membrane filled with liquid, so as to obtain an uplift of this inner membrane and of this liquid relative to the outer membrane, to an equilibrium position;

-wait the time necessary for the setting of the concrete beyond the plasticity phase of this concrete;

- complete the pouring of the liquid concrete.

The installation includes the buried tank (17) and comprises a dwelling (1), a pipe (10) for evacuating waste water from the dwelling to the tank (17), a tank (4) for recovering the biogas produced. in the digester (2), and a pipe (15) for transporting this biogas towards the dwelling (1).

The present invention relates to a method of building a buried tank, in particular a digester. It also concerns the biogas production facility including this digester.

The term tank must be understood in the broadest sense; apart from a digester, it can be a septic tank or a water tank, for example.

Ecological concerns are increasingly leading to the design of habitats that are as autonomous as possible, in particular in terms of energy production and recycling of wastewater.

It was thus designed to equip a habitat with a buried digester, that is to say with a tank receiving the waste water coming from the dwelling as well as organic matter, such as grass mowing or other gardening waste, this digester being able to produce biomass whose degradation produces gas, called biogas.

The existing methods for constructing such a buried digester are not entirely satisfactory, given their complexity and their cost of implementation, which constitutes a notable limitation in the development of this type of technique.

The present invention aims to remedy this essential drawback, by providing such a method, which is significantly simpler to implement than an existing method.

The invention also aims to provide a biogas production installation including this digester.

The process concerned comprises the following stages:

- design the buried tank with a spherical or ovoid shape and with a concrete wall, this wall being intended to be poured between an outer membrane and an inner membrane of spherical shapes, these membranes being made of flexible materials; calculating the mass presented by the internal membrane and a quantity of liquid completely filling the volume delimited internally by this internal membrane; determining the pressure exerted by the concrete during its pouring between said external and internal membranes so that the quantity of concrete poured is capable of lifting the internal membrane and said quantity of liquid, to an equilibrium position corresponding to l arrival of the concrete substantially at the mid-height of this internal membrane; the pouring height between the membranes must be such that the pressure of the concrete to be poured to constitute the lower half of the tank is substantially equal to the pressure exerted by mass of the internal membrane and of the liquid contained in this membrane, under this internal membrane

- provide the outer membrane with an upper tubular extension;

- arrange an excavation in the ground, intended to receive the tank;

- Place in the bottom of this excavation a loose material having a cohesive structure, that is to say retaining a shape when this shape is arranged in it;

- arrange a cavity in this loose material, having a shape corresponding to the outside shape of the lower half of the tank to be produced;

- Place a support structure above said excavation, place the outer membrane in said cavity and connect the upper tubular extension of this membrane to said support structure;

- placing said internal membrane inside said external membrane;

- fill the volume delimited by the internal membrane with liquid;

pouring liquid concrete between the outer membrane and the inner membrane to substantially half the height of said inner membrane filled with liquid, so as to obtain an uplift of this inner membrane and of this liquid relative to the outer membrane, to said position of equilibrium;

- wait the time necessary for the setting of the concrete beyond the plasticity phase of this concrete;

-before or after this concrete pouring, set up a tube in said upper tubular extension that includes the outer membrane, this tube coming to rest against the inner membrane and being connected to the latter in a sealed manner;

complete the pouring of the liquid concrete into the space provided between said external membrane and said internal membrane and then into the space delimited between said tube and the upper tubular extension of the external membrane, up to the desired height for the wall in concrete, while concomitantly filling the space between the outer membrane and the wall of the excavation corresponding to the volume located between the outer membrane and this wall of the excavation.

The method according to the invention is thus much simpler, less time-consuming and less expensive, to implement than the existing methods. In particular, the shape of the tank allows resistance under the best conditions to the pressure exerted by the material or materials contained in the tank, and also makes it possible to minimize the wall surface that this tank presents for a given volume of this tank. . In addition, the use of an internal membrane for the construction of the tank allows perfect containment of the fumes, and the fact that this membrane is flexible allows the part of this membrane present on the upper part of the tank to deform according to the pressure existing in the tank, and therefore to adapt to this pressure. The collapsed state or not of this part of membrane also makes it possible to immediately visualize the existence of a pressure or not inside the tank.

Said movable material is preferably formed by wood chips or fragments.

These shavings or fragments of wood, by their shape and the fibers of which they are made, tend to interpenetrate and agglomerate in a reversible way when they are packed, and therefore have the capacity to form the above-mentioned cohesive structure. . In addition, they constitute a very good thermal insulator of the tank vis-à-vis the surrounding soil.

The outer membrane and the inner membrane may in particular be constituted by a geo-membrane of PVC, polyethylene or other polymeric material.

The liquid used to fill the internal membrane can in particular be water.

The step consisting in fitting the aforementioned cavity into said movable material may in particular include the use of a tool having a shaft and a wall mounted to pivot around this shaft, having a shape representing one half of the lower section of the cavity to to arrange; the shaft is intended to be placed in the center of a shapeless pre-cavity arranged in said movable material, according to the depth of the cavity to be obtained, and said wall is pivotally actuated around this shaft so as to machine the movable material until the constitution of the wall defining the cavity to be obtained.

This cavity is thus arranged in a simple manner.

Preferably, the method comprises, after the step of fitting the outer membrane and before the step of fitting the inner membrane, a step consisting of fitting one or more heating elements intended to carry out heating of the wall of the tank, this or these heating elements being intended to be embedded in the concrete which is poured into said space existing between the two membranes.

Each heating element may in particular be in the form of a tube constituting a coil, intended for the circulation of a heat transfer fluid, in particular for the circulation of water heated by means of one or more solar collectors.

Preferably, the method can comprise the step consisting in placing, between said external membrane and said internal membrane, before the filling of this internal membrane, one or more reserve blocks, in particular made of polystyrene, allowing subsequent easy drilling of the wall of the tank for the establishment of conduits and / or pipes to which the tank must be connected. When this tank is a digester, these pipes and / or pipes are in particular the supply pipe for this digester with waste water and other organic matter, the digestate evacuation pipe, a pipe for manual introduction of organic matter and / or an inspection / cleaning inspection of the tank.

Said introduction pipe can in particular be equipped with a propeller for agitating the contents of the tank, making it possible to stir this content in this tank.

As regards the installation according to the invention, the buried tank is that of a digester; the installation includes a house, a pipe for discharging waste water from the house to the digester tank, a tank for recovering the gas produced in the digester and a pipe for transporting this gas towards the house .

This installation may further comprise, when the digester is equipped with a heating element in the form of a coil, one or more solar panels for heating a heat-transfer liquid, in particular water, contained in this coil.

The installation can also include a phyto-purification zone.

In this case, the dwelling may in particular comprise an upper wall coated with earth and planted with grasses or other plants (dwelling known commercially under the name NATURADOME), and the installation may comprise a diffusion pipe, on or in this earth , purified liquid produced by the phyto-purification zone.

The invention will be clearly understood, and other characteristics and advantages thereof will appear, with reference to the appended schematic drawing, representing, by way of nonlimiting example, a possible embodiment of the installation that it relates to. , and different parts of the digester that this installation includes, during successive stages in the construction of this digester.

Figure 1 is a partial view, in section, of a house known commercially under the name NATURADOME and is a view, also in section, of the digester associated with this house;

Figure 2 is a view extending the right part of Figure 1, showing an area of phyto-purification of the digestates produced by the digester; and FIGS. 3 to 11 are schematic views, in section, of a succession of steps in the digester manufacturing process.

FIGS. 1 and 2 represent a biogas production installation essentially comprising a dwelling 1, a buried digester 2 associated with solar collectors and panels 3, a tank 4 for storing the biogas produced, and a phyto-purification zone 5.

The dwelling 1 is of the type comprising a main wall 6 forming a dome, covered with a layer 7 of insulation, in particular in agglomerated wood chips, and a layer of soil 8 covering this layer of insulation, in which is planted grass or other plants.

Housing 1 may in particular be that described in patent application No. FR 3 022 270 (housing known commercially under the name NATURADOME).

This house 1 is connected to one or more pipes 10 for discharging waste water. It also contains equipment operating on biogas, such as an electric generator 11, a cooking plate 12 and a heating boiler 13 operating on biogas, supplied by a pipe 15 coming from the tank 4.

The digester 2 is buried in an excavation and is positioned in the latter by means of a mass 16 of chips or fragments of crushed wood, completely filling the space existing between the excavation and the digester 2.

The latter has a spherical tank 17, with a variable capacity, from 3,000 to 15,000 liters depending on the effluent deposits likely to be produced by the dwelling, and includes a prefabricated manhole 18 flush with the ground surface. This reservoir 17 and this sight 18 are formed by a concrete wall about twenty centimeters thick, poured between an outer membrane and an inner membrane, having, in the example shown, a spherical shape, as will be described more far. The wall of the tank contains a coil 19 for circulating water heated by means of solar collectors 3.

The digester 2 also comprises a pipe 22 for evacuating the biogas it produces, equipped with a filter and a gasometer, and connected to the tank 4.

It further comprises a tube 24 of diameter of the order of 500 mm, making it possible to introduce into the tank 17 mowing grass, gardening waste or other biodegradable waste, equipped with a tree and d a liquid stirring propeller 25 contained in the tank, a pipe 26 for evacuating the digestates in the direction of zone 5 and an inspection 27 for cleaning and cleaning the tank 17.

The solar panels and collectors 3 include solar collectors for heating the water circulating in the coil 19, and photovoltaic panels for producing electricity. They are supported by a metal or masonry structure 28.

Line 26 opens into a recovery tank 30 containing a pump 31 for conveying digestates in the direction either of zone 5, or of grass or other plants planted in the layer of soil 8, via line 42. The tank return 30 also includes a pipe 32 for discharging the overflow.

Zone 5 is delimited by a slope 35 and successively comprises, from bottom to top, a geotextile membrane, a layer of gravel with a thickness of at least twenty centimeters, in which a drainage pipe 36 is contained, a transition layer in gravel of ten to twenty centimeters thick, a layer of sand of thirty centimeters thickness in which is contained conduit 37 of diffusion of digestates, and a layer of sand of thickness of twenty centimeters, receiving a planting of plants 38, especially rushes. The embankment 35 receives a peripheral rip-rap 39 of the order of forty centimeters on the side, in self-locking elements.

The water is treated by phyto-purification by the biomass present on the cover and filtered by passing through the strong layer of soil 8 and is collected at the base of the vault by the drainage system 44. Part of this purified water is directed to the toilet in house 1 or to a basin for recovering this water for watering. This water can also be treated by micro filtration and sterilization device to ensure a wider domestic use (water for washing machines, toilet water). In the case where the system is not implemented near a dome corresponding to the aforementioned patent No. FR 3 022 270, the effluents will be directed to zone 5.

The drainage pipe 36 is connected to a recovery tank 40, the pump 41 of which is connected by a pipe 43 allowing part of the purified water to be directed towards the toilets of the dwelling 1 or towards a basin for recovering this water. for watering.

FIGS. 3 to 11 illustrate successive stages of the method for producing the digester 2.

The first step is a calculation step consisting of:

- To calculate the mass presented by the aforementioned internal membrane, which is spherical, and an amount of water completely filling the volume delimited internally by this internal membrane;

to determine the thickness that the wall of the tank 17 must have and the height of pouring of the concrete intended to constitute the wall of the tank 17 so that the quantity of concrete poured between said external and internal membranes is capable of lifting the membrane internal and said quantity of water, up to an equilibrium position corresponding to the thickness of concrete sought between the two membranes 61, 65; the pouring height between the two membranes to constitute the lower hemisphere of the tank 17 must be such that the pressure of the concrete under the internal membrane 65 is substantially equal to the hydrostatic pressure at the base of the internal membrane 65 to lift it according to the thickness of concrete sought. Altimetric control of the base of the internal membrane 65 can easily be carried out via the line 22 by which the internal membrane is filled with water.

Once these calculations have been made, the steps for producing digester 2 are as follows:

- Arrange the excavation 50 in the ground, intended to receive the tank 17, with possible installation of a support frame 51 (see Figure 3);

- Place in the bottom of this excavation 50 wood chips or fragments of crushed wood 52, having a unit size of the order of 1 to 5 cm, which constitute a loose material having a cohesive structure, that is to say - to say retaining a form when this form is arranged in him;

- Arrange a hemispherical cavity 55 in these chips and fragments 52, having a radius corresponding to the outside radius of the tank 17 to be produced; this arrangement is made using a tool having a shaft 56 and a quarter-circle wall 57 pivotally mounted around this tree, the shaft 56 being placed at the center of a shapeless pre-cavity arranged in the shavings and fragments 52, depending on the depth of the cavity to be obtained, and said wall 57 is pivotally actuated around the shaft 56 so as to machine the shavings and fragments 52 until the formation of the hemispherical wall delimiting the cavity 55 to be obtained (see figure 4).

- Place a support structure 60 above the excavation 50, place the outer membrane 61 in said hemispherical cavity and connect an upper tubular extension 62 formed by this membrane to said support structure 60 (see Figure 5);

put in place, against the external membrane 61, one or more reservation blocks (not shown), in particular made of polystyrene, allowing easy subsequent drilling of the wall of the tank 17 for the connection of the pipes 10 and 26, of the pipe 24 and look 27;

- Fit the tube or tubes constituting the coil 19 (see Figure 6);

- Place the internal membrane 65 inside the external membrane 61;

- Put in place the pipe 22 and use this pipe to fill with water 66 the volume delimited by the internal membrane 65, which leads the internal membrane 65 to bear against the coil 19 and, beyond the latter , against the outer membrane 61 and against the support formed by the wood chips and fragments 52 (see FIG. 7);

pour liquid concrete 70 between the outer membrane 61 and the inner membrane 65 to substantially the height of the equator of the sphere formed by the inner membrane 65 filled with water 66, so as to obtain an uplift of this membrane internal and of this water with respect to the external membrane 61, according to the thickness which the wall of the tank 17 must have at the lower level of this tank (see FIG. 8);

- wait for the time (one to two hours) necessary for the setting of the concrete beyond the plasticity phase of this concrete;

put a tube 71 in the upper tubular extension 62 that the external membrane 61 includes, this tube 71 coming to rest against the internal membrane 65 and forming a manhole;

-complete the pouring of liquid concrete 70 in the space provided between said outer membrane 61 and said inner membrane 61 then in the space defined between the tube 71 and the upper tubular extension 62, up to the desired height for the wall concrete, which is the height of an upper face that forms the support structure 60 in the example shown (see Figure 9), while concomitantly filling with wood chips 52 the space delimited by the excavation 50 and the outer membrane 61;

- pierce the wall of the tank 17 at the places of the reservations then set up the pipes 10 and 26, the pipe 24 and the manhole 27 (see FIG. 10);

- Complete the installation of wood chips and fragments 52 then backfill the excavation 50, up to the support structure 51 in the example shown (see Figure 11).

The invention thus provides a method of constructing a buried tank 17, in particular a digester, having the decisive advantages clearly simpler, less time consuming and less expensive, to implement than the existing methods. The spherical shape of the tank 17 allows resistance under the best conditions to the pressure exerted by the material or materials contained in the tank, and also makes it possible to minimize the wall surface that this tank has for a given volume of this tank. In addition, the use of the internal membrane 65 for the construction of the tank 17 allows perfect containment of the emanations, and the fact that this membrane is spherical and flexible allows the part of this membrane present in the bottom of the tube 71 to deform as a function of the pressure existing in the tank 17, and therefore adapt to this pressure. The collapsed state of this part of the membrane (visible in FIG. 1 in dashed lines) also makes it possible to immediately visualize the existence of a pressure or not inside the tank 17 and to constitute a buffer stock of biogas as a gasometer.

Claims (11)

1. Method for constructing a buried tank (17), in particular a digester (2), characterized in that it comprises the steps consisting in: - design the buried tank (17) with a spherical or ovoid shape and with a concrete wall, this wall being intended to be poured between an outer membrane (61) and an inner membrane (65) of spherical shapes, these membranes being flexible materials; calculating the mass presented by the internal membrane (65) and an amount of liquid completely filling the volume delimited internally by this internal membrane (65); determining the pressure exerted by the concrete during its pouring between said external and internal membranes so that the quantity of concrete (70) poured between said external and internal membranes (61, 65) is capable of lifting the internal membrane (65) and said quantity of liquid, up to an equilibrium position corresponding to the arrival of the concrete substantially at the mid-height of this internal membrane (65); ; the pouring height between the membranes (61, 65) must be such that the pressure of the concrete (70) to be poured to constitute the lower half of the tank (17) is substantially equal to the pressure exerted by mass of the internal membrane (65) and the liquid contained in this membrane, under this internal membrane (65). - provide the outer membrane (61) with an upper tubular extension (62); - Arrange an excavation (50) in the ground, intended to receive the tank (17); - Place in the bottom of this excavation (50) a loose material (52) having a cohesive structure, that is to say retaining a shape when this shape is arranged in it; developing a cavity (55) in this loose material (52), having a shape corresponding to the outside shape of the lower half of the tank (17) to be produced; - placing a support structure (60) above said excavation (50), placing the outer membrane (61) in said cavity (55) and connecting the upper tubular extension (62) of this membrane to said support structure (60); - placing said internal membrane (65) inside said external membrane (61); - fill with liquid (66) the volume delimited by the internal membrane (65); pouring liquid concrete (7) between the outer membrane (61) and the inner membrane (65) until substantially halfway up said inner membrane (65) filled with liquid, so as to obtain a lifting of this membrane internal (65) and of this liquid with respect to the external membrane (61), up to said equilibrium position; - Wait for the time necessary for setting the concrete (70) beyond the plasticity phase of this concrete; - before or after this concrete pouring, put a tube (71) in said upper tubular extension (62) that includes the outer membrane (61), this tube coming to rest against the inner membrane (65) and being connected to that -this tightly; -complete the pouring of liquid concrete (70) in the space provided between said outer membrane (61) and said inner membrane (65) then in the space defined between said tube (71) and the upper tubular extension (62) of the outer membrane (61), up to the desired height for the concrete wall, while concomitantly filling the space between the outer membrane and the wall of the excavation corresponding to the volume located between the membrane external and this wall of the excavation. 2. Method according to claim 1, characterized in that said loose material is formed by wood shavings or fragments of crushed wood (52), having a unit size of the order of 1 to 5 cm. 3. Method according to claim 1 or claim 2, characterized in that the outer membrane (61) and the inner membrane (65) consist of a geo-membrane made of PVC, polyethylene or other polymeric material. 4. Method according to one of claims 1 to 3, characterized in that the step of arranging said cavity (55) in said movable material (52) includes the use of a tool having a shaft (56) and a wall (57) pivotally mounted around this shaft, having a shape representing one half of the lower section of the cavity to be fitted; the shaft (56) is intended to be placed in the center of a shapeless pre-cavity arranged in said loose material (52), according to the depth of the cavity (55) to be obtained, and said wall (57) is actuated by pivoting around this shaft so as to machine the movable material (52) until the constitution of the wall defining the cavity (55) to be obtained. 5. Method according to one of claims 1 to 4, characterized in that it comprises, after the step of fitting the outer membrane (61) and before the step of fitting the inner membrane ( 65), a step consisting in setting up one or more heating elements (19) intended to produce a heating of the wall of the tank (17), this or these heating elements being intended to be embedded in the concrete (70) which is poured into said space existing between the two membranes (61, 65). 6. Method according to claim 5, characterized in that each heating element is in the form of a tube constituting a coil (19), intended for the circulation of a heat transfer fluid, in particular for the circulation of water heated to by means of one or more solar collectors (3). 7. Method according to one of claims 1 to 6, characterized in that it comprises the step consisting in setting up, between said outer membrane (61) and said inner membrane (65), one or more reservation blocks , in particular made of polystyrene, allowing easy drilling of the wall of the tank (17) for the subsequent installation of conduits (10, 26) and / or pipes (24) to which the tank (17) must be connected. 8. Biogas production installation including the buried tank (17) according to one of claims 1 to 7, characterized in that this tank (17) is that of a digester (2), and in that the installation comprises a dwelling (1), a pipe (10) for evacuating waste water from the dwelling to the tank (17) of the digester (2), a tank (4) for recovering the gas produced in the digester (2) , and a pipe (15) for transporting this gas in the direction of the dwelling. 9. Installation according to claim 8, characterized in that it comprises a phyto-purification zone (5). 10. Installation according to claim 8 or claim 9, characterized in that the dwelling comprises an upper wall coated with earth (8) and planted with herbs or other plants and in that the installation comprises a pipe (42) of diffusion, on or in this earth (8), of the purified liquid produced by the phyto-purification zone (5). 11. Installation according to one of claims 8 to 10, characterized in that the tank (17) of the digester (2) receives a pipe (24) for manual introduction into it of organic matter, equipped with a propeller (25 ) of stirring the contents of the tank (17), making it possible to stir this content in this tank (17). 1/4