FR2710072A1 - Vertical modular continuous digester - Google Patents

Abstract

Modular continuous digester of the vertical type, capable of digesting ground organic materials. It converts them, under the effect of bacteria, into biomethane and into fertile compost. It is provided in the form of a succession of modules (1). The methanisable material enters via the pipe (6). After passing into the various elements, it becomes degraded and leaves via the tube (8). The biomethane is released from each compartment via the tubes (2) into a collector (4). The substrate or compost is then sent to a centrifuge by means of pipes and a pump (10), (11) and (15).

Description

 The present invention relates to, as an industrial product, a modular continuous digester of the vertical type.

 This digester according to the invention allows, with an excellent yield to produce organic methane, by the anaerobic fermentation of plant materials.

 The process of plant degradation in nature has been known for a long time.

Air-protected bacteria attack cellulose to transform it into fertilizing elements
This biological reaction is accompanied by the release of methane.

 The subject of the present invention is, by appropriate means, the industrial use of this natural phenomenon which makes it possible to produce a combustible gas, biomethane, by recycling organic waste of all kinds.

 Modern society generates an increasing amount of waste.

 The recovery and reconversion into energy of two ci arise with more and more acuity.

 The digestion of organic matter with production of biomethane on the one hand and fertile residues on the other would be a profitable solution to the use of part of urban and agricultural waste.

 The main characteristic of the continuous digester is its resemblance to a digestive system.

 He cultivates bacteria, for this he needs an adequate temperature and must be fed regularly with a product previously prepared and sown.

 To date many models of digesters have been built and tested.

 These devices resse;, zbl generally to fermentation tanks cl nu lesqueiles the materials to be digested are introduced in a global manner.

 It is very difficult to control, in a very large mass of product, the smooth running of the methane fermentation process.

 The digester that we are going to describe, of an original design, makes possible, with an appreciable yield the transformation of certain organic waste, into gaseous fuels; methane on the one hand and fertilized compost on the other.

 The biomethane produced in this installation can be injected into an urban distribution network or else be transformed on site into electrical energy.

 The present invention is akin to a digestive tract.

 Organic matter is forced to take a well-defined route.

 The temperature of the assembly is subject to permanent control and regulation.

 The speed of passage of materials, reduced to paste or mud, are also controlled according to the action of methanogenic bacteria.

 The invention is also characterized by these modular elements.

 We can design standard route elements that we justapose to obtain the required digestion capacity.

 The subject of the present invention, as an industrial product, is a remarkable and modular methanization chain at the request of flow requirements.

 The realization of these treatment elements which have several variants, do not require any particular technique in sheet metal construction.

 All the materials used are known.

 The characteristic objects and advantages of the various variants will also appear in the description which will be given below, relating to the embodiments, represented in the accompanying drawings.

On these drawings
~ Figure (1) shows an elevational view of the vertical digester.

 ~ Figure (2) shows a top view of the digester.

 ~ Figure (3) shows an elevational view of a model of digestion box.

 Figure (4) shows a side elevation view of the previous module.

 Figure (5) is a top view of the element shown in Figure (3).

Figure (6) is a sectional view of Figure (3) along AA
ja figure (7) shows a sectional elevation view of a complete methanization chain.

 FIG. (8) represents a sectional elevation view of a digestion module comprising helical arm accelerators with their oto-reductor =.

 It also represents the nests or traps of bacteria with their heating coil.

 ~ Figure (9i is a side sectional view of Figure (8) along CC.

 ~ Figure (10) is a sectional view of Figure (8) along BB.

 ~ Figure (11) is the perspective view of an empty basket of alveolar mineral elements used to support the production of methanogenic bacteria.

 Figure (12) is a sectional elevation view of a variant module.

 Figure (13) is a top view of the previous figure.

 ~ Figure (14) is a sectional view of Figure (12) along DD.

 Figure (15) is a sectional elevation view of a standard digester element according to the variant of Figure (12).

 Figure (16) is a sectional elevation view of Figure (12), it is also a variant of Figure (15) concerning the transfer elements and bacteria traps.

 According to the exemplary embodiments shown, the digester object of the invention consists of standard elements entirely built in the workshop.

 According to Figure (1), the digester object of the invention consists of several elements (1).

 Each element represents a tube in, the level of matter of one and equal to the level of the other, according to the principle of communicating vases.

 Figures (3) and (4) show the constitution of a digestion chamber.

 In the case of Figure (1), this element is constructed by the assembly of two cylindrical tubes, held to one another along a mediator, by known means rivets for example.

 According to one embodiment, four sheets form the side walls of an element.

 They are also fixed by rivets to the mediatrics and welded at the four angles by known means.

 At the ends of each of the tubes are welded metal plates cut according to the diameter of these, all assembled forming a rectangular parallelepiped outside.

 A metal chest forms the upper part, the interior is separated in two by a partition.

 The lateral sides of the box have portholes (14) allowing the good flow of the product to be viewed.

 A metal chest forms the lower part, it has a flange with solid seal (13) thus ensuring the emptying of a standard element.

 According to Figure (6) which shows a section of Figure (3) along AA, it can be seen that spaces (52) exist between the outer walls of the tubes and the outer walls of the standard element.

 They are six in total and are used for the circulation of a heat transfer fluid necessary to maintain the temperature of the digester.

 Three pipes (17) on each side at the bottom are used for the entry of the fluid.

 Three pipes (18) at the top of each side are used for the outlet of the fluid.

 According to Figure (1) the digester object of the invention comprises five standard elements (1).

 These U-shaped elements are stacked one after the other, they are assembled on site by known means, welding or bolting.

 The heating circuit will be sealed relative to the circuit of the materials to be digested and the entire digester will be sealed relative to the outside.

 Each element will be drainable through the tubing (13).

 The portholes (14) allow you to see the interior and the path of the product to be digested.

 The material to be digested is sent by the pump (5) sucking in (7) and discharging through the tube (6).

 It runs from top to bottom and from bottom to top in each element.

 The digested material is then evacuated through the tubing (8), to a retention pit (9).

 It is taken up by the pump (10) to be evacuated by the tube (15).

 The suction piping in the pit includes a strainer with non-return valve (11).

 The pump types (5) and (10) are adapted to the viscosity of the product to be conveyed.

 The methane is released from each digestion element by a pipe (2), each connected to a collector (4) with a stop valve (3).

 Figure (2) shows a top view of the digester described above.

 You can see the lighting portholes (16) placed on the roof of the digester.

 The intervals for the circulation of the heat transfer fluid are marked (52).

 The civil engineering on which the assembly is based bears the reference (12).

 Figure (7) is the schematic representation of a complete methanization chain.

 Plant and organic waste arrives at (19) and is fluidized by a wet grinder (21) inside a pit (20).

 When the viscosity has become compliant, the pump (6) sends the product to the inlet of the digester.

 This sludge is then brought to a temperature suitable for the action of bacteria, it is maintained there by a regulation system.

 According to the principle of vases omauniquallts the product will go from compatirm in compartment in the direction of flc.

 Under the effect of bacterial attacks it will degrade, chemical reactions will produce new molecules and in particular methane.

 The digested product will end its course through the tubing (8) in the pit (9).

 It will be taken up by the pump (10) to send it to an automatic centrifuge (22) which will separate solids and liquids.

 The partially dehydrated residue, the compost, will be removed in (23) and (24) to fertilize the soil.

 The recovered liquid, loaded with bacteria, will feed the wet grinder through the piping (54).

 This effluent will therefore be used for the primary sowing of waste at the entrance to the chain.

 In this first description, for greater clarity, the description of the sludge access and mixing device has been neglected.

 But also the means provided for the permanent culture of bacteria and their refuges in the digestion medium.

 Figure (8) shows a sectional view of a previously described digestion module.

 In each of the cylindrical tubes can move an archimedean screw or helical kneader (37) whose function is to stir the product in order to make it more uniform in viscosity and temperature.

 Each module has two which also have the function of product accelerator.

 They rotate in opposite directions, one forcing the descent, the other for raising the product.

 They are driven by C o-reducers to variable speed drives (33) placed on the roof of the device.

 According to the drawings in Figures (8) and (9) it is easy to understand the direction of flow of the product inside the digestion module, which is shown by all the arrows.

 In the lower part of the module, two baskets or mesh containers (38) are filled with crushed volcanic rock or any other synthetic cellular mineral material, for example.

 These materials have the properties of harboring colonies of methanogenic bacteria.

 These containers are heated using a coil (39) in which a heat transfer fluid circulates which maintains, by means of a regulation system, a constant temperature favorable to the development of bacteria.

 Since this medium is not swept away by the movement of the product, these bacteria proliferate quickly there and permanently seed the environment.

 It can be understood that this culture system inside the digestion medium is essential for the proper functioning of the process.

 Figure (9) is a sectional view along CC of Figure (8).

 Figure (10) is a sectional view along BB of Figure (8).

 According to Figures (8) and (9), the containers (38) or bacteria traps are installed on slides and removable from the outside by doors fitted after emptying the module by (13).

 A tubing (40) serves as an inlet and outlet for the heating fluid.

Figure (10) highlights the heating circuits (52) of the module, as well as the inlet pipes of the heating fluid
Figure (11) is the perspective view of a mesh container (38) empty of its aggregates with its heating loop (39).

 When it is filled with cellular materials that are resistant to the environment, it acts as a nest from which bacteria reproduce and proliferate to contaminate the methanisable substrate as it passes.

 Figure (12) shows the variant of a digester module.

 This variant has the distinction of being designed and produced entirely in membrane tubes.

 The use of this material in the design of digesters has many advantages, in particular it accomplishes two functions, the realization of the container with the incorporated heating circuit.

 The advantages of this variant will emerge from the description which follows.

 According to Figure (12) the methanisable materials are injected through the tubing (14) upstream of a check valve (31).

 At the outlet of this valve, the material is taken up by a worm elevator (32) which mounts the latter as far as the inlet chamber (36), driven by a geared motor (33).

 This anaerobic digestion module also consists, as before, of a U-shaped course.

 The four walls are tubular as well as the middle partition.

 The bottom of this module is constituted by the lateral tubular sides bent at the bottom which are stuck on the supply collectors (30).

 The middle wall is also made of tubes welded on membranes.

 It comprises a manifold (30) for supplying the latter with heat transfer fluid.

 This fluid after passing through the tubular screen comes out to the upper manifold (30).

 The front and rear walls of this enclosure are also made in the same way.

 Figure (12) is a section along EE of Figure (33), top view of a tubular wall module.

 The material to be degraded contained in this digestion element is brought to the appropriate temperature by convection of the walls and partition.

 According to Figure (14), which is a section of Figure (12) according to EE, we can see appear the two rectangular chambers which constitute the described digester.

 All the tubes (29) are interconnected by a membrane welded to the machine.

 This material is known and makes it possible to create sealed spaces with heated walls.

 For a good understanding of the route, bacteria nests and accelerators are not shown in figure (12).

 The material arriving in the chamber (36) will flow in the first path, to rise in the second following the arrows.

 One can think that the matter which will leave in the room (34) will keep a constant level compared to the entry (36), according to the principle of the communicating vases.

 The siphon (34) is a hydraulic seal which lets the liquid substrate through, but through methane.

 The tubing (35) allows the emptying of the siphon.

The sheath (8) is used for the evacuation of the digested products
Figure (15) shows a variant of the digester described above.

 I1 is equipped with at least two archimedean screws (37) used for mixing and advancing the product.

 These two screws are driven by the geared motors (33).

 Crosspieces (45) support the bearings which are stopped at the bottom.

 Baskets (41) hung on the interior walls of the digester.

 These mesh baskets are filled with crushed volcanic rock or any other cellular mineral.

 Their function is the culture of methanogenic bacteria.

 They are kept at temperature by the radiation from the walls.

 These elements (41) are nests or refuge for bacteria, they proliferate there and inoculate the whole surrounding environment.

 The digestion module can be emptied through the tubing (42) located in the lower part of the device.

 The digester inlet endless screw (32) can also be heated by circulation of heat transfer fluid in a double jacket according to the example in FIG. (12).

 The entire digester enclosure is identical to the description in Figure (12).

 According to the invention, the methane is released from each of the compartments by the pipes (2).

 According to a variant of the invention, the figure (16) differs from the figure (15) only by the transfer mechanisms of the product and the inoculation of the medium.

 In the description which follows one will be able to realize the difference of the transfer system and its advantages.

 The digester supply device (32), the tubular enclosure (29) with the inlet and outlet manifolds (30), the product outlet siphon, the methane evacuation pipes (2), remain identical in figure (15).

 According to another characteristic of the invention, the bacteria nests move alternately in the medium to be digested.

 Indeed mesh containers (50) filled with a cellular mineral product, are maintained in a metal frame (47).

 These volumes in more or less large numbers are animated by a movement back and forth from bottom to top and from top to bottom.

 The movement of these is ensured by hydraulic or pneumatic cylinders or any other system that can act by programming.

 These devices have a double function, they ensure the culture of bacteria, their diffusion in the medium to be digested, but also, the movement of methanisable organic matter.

 The device which ensures the mixing and movement of the material in the body of the digester consists of pallets (48).

 Each pallet has a stop which allows it to be blocked in a given position.

 For example, in the drawing of Figure (16), the mobile located in the right compartment has flaps whose stop is located at the top.

 It is clearly understood that when the mobile (47) is going to move upwards, the mass of material will necessarily incline pallets or valves (48) downwards.

 In the opposite direction, that is to say, the downward movement, the pallets or flaps will come into abutment in the position of the design thus offering the material a maximum drag.

 This will push the mass of pasty product down, thus facilitating its advancement in the compartment.

 At the same instant the mobile (47) in the left compartment will be animated in a reverse movement, moving upwards.

 The flaps having an inverted position relative to the previous mobile, will push the material upwards.

 We understand very well that these two mobiles or pistons animated by a back and forth movement, will, according to their frequency of displacement, force the movement of the material at more or less high speeds in the digester, object of the invention.

 This system of shutters or summary valves will also have the effect of practicing permanent mixing of the medium.

 The material will infiltrate in greater or lesser quantity through bacteria nests, thereby causing constant sowing of the medium by mass displacement.

 These pistons or mobiles (47) are motorized using jacks (49).

 They slide at the bottom of the digester in the bearings installed on the crosspieces (51).

 The number of these pistons (47i can vary depending on the capacity of the digester, ie the passage section of the compartment in which they are installed.

 Their number will always be at least two.

 These mobiles (47) with the different functions that we have described, will be warmed up to the temperature that will allow the maximum production of methanogenic bacteria.

 The number of these will depend on the efficiency of the digester and the production of methane.

 These bacteria nests will therefore be brought to a certain temperature by means of coils in which a heat transfer fluid will circulate.

 Flexible connections inside the digester will ensure a constant supply of heat transfer fluid to the incorporated exchanger, thereby facilitating back and forth movements.

 This device is not shown in the accompanying drawings.

 Appropriate regulation will ensure a constant temperature of the mobile bacteria nests which are the subject of the invention.

 Figure (17) shows a digester with two digestion modules.

 Only the body of each module is shown.

 The bacteriological culture, stirring and transfer device described above is not shown in this drawing.

 It can easily be understood that this invention has a multitude of advantages.

 In the yield of the digestion of organic matter in their volume to be digested but also in the retention time of the products.

 In the case of the examples described, the capacity of an installation will depend on the passage section of a module but also on its height.

 It can also depend on the number of modules that will be added one after the other.

 This invention is simply akin to a bowel that is arranged vertically.

 To increase the digestion capacities, it will suffice to multiply the number of standard modules which will be placed one after the other according to Figures (1) and (17).

 Because the material to be digested travels in vertical U-shaped paths, one can easily check the proper functioning of each part of the digester.

 All possibilities are allowed to act on the various parameters which will ensure the smooth running and optimal performance of the installation.

 It is known that the phenomenon of degradation of organic matter occurs under the more or less intense action of bacteria whose development is linked to the temperature and the nature of the medium.

 Therefore, in the accompanying drawings are shown the circuits in which circulate the calories that are provided to facilitate bacteriological reactions.

 These calories are produced by the combustion in a boiler of a small quantity of methane taken from the production of the digester.

 These calories can also be transferred by heat pump or other system.

 I1 was deliberately neglected the external insulation of all the heated elements of the methanization chain.

 All insulating materials and their use which avoid too much heat loss are known.

 As we could realize during the description of this digester and its variants, the operation is very simple, its construction poses no particular technical problem.

 This digester, with its various variants, object of the invention has the economic advantage of using in a profitable and large-scale manner, all the plant and organic waste that our civilization generates.

 I1 therefore transforms this waste on the one hand into latent energy "biomethane" and on the other hand into fertilizer compost likely to partially replace chemical fertilizers.

 Everyone knows that the combustion of methane does not cause excessive pollution since it does not contain sulfur.

 The regulation of the burners allows excellent combustion.

 Biomethane can power a whole range of motor vehicles, in particular city buses.

 This type of digester could equip all urban and rural treatment plants, which currently generate large quantities of carbon dioxide.

 We know that the functioning of these is aerobic and that the principle of degradation and based on the oxygenation of carbon, or production of carbon dioxide and atmospheric pollution.

 In urban areas, effluents from cities, mowing of lawns in green spaces, mulch from pruning trees, plant and organic matter from household waste can produce a significant amount of methane using suitable digesters.

 This gaseous fuel can be transformed into electrical energy or else be injected into the urban gas distribution network.

 In the rural area, all agricultural waste can be methanised with profitability.

 Slurries that are known to be polluting can generate large quantities of biomethane.

 Various haulm, straw, manure, animal excrement of all kinds can be easily digested in this digester object of the invention.

 Agriculture could benefit from all its waste but also from appropriate vegetable crops in the land currently left fallow.

 All by avoiding pollution, this energy and fertilizer production would be a plus in the current agricultural economy.

 It would also make it possible to return to more organic than chemical agriculture.

 The use of this remarkable tool would also allow the development of our forest wealth.

 That is to say the transformation into biomethane, therefore into energy, of all the detritus which gathers the ground of our forests (dead wood, leaves, brushwood as well as all sawmill waste etc ...).

 The substrate would of course return to the fertilization of the trees.

Claims (23)

 1) Vertical type conti molular digester, allowing to produce biological methane by the controlled action of methanogenic bacteria.  This digester is characterized by a combination of modules (1) each having a U-shaped path, according to the principle of communicating vessels.  2) Digester according to claim 1, characterized by the association of two cylindrical tubes (60) interconnected by known means.  They form the vertical U-shaped path of a modular element.  3) Digester according to claim 2 characterized by the assembly of sheets (55) and (56) at the end of the tubes (60), delimiting the path of the material to be digested and the module heating circuit.  4) Digester according to claim 3 characterized by the assembly of sheets (57) and (58) closing the periphery of the module and constituting a rectangular parallelepiped.  5) digester module according to claim 4 characterized in that the sheets (55) (56) (57) and (58) assembled by known methods form spaces (52) sealed, in which circulates a fluid coming to reheat the material being digested in the tubes (60).  6) Digestion module as claimed in claim 5 characterized by base pipes (17) and high (18) through which enters and leaves the heat transfer liquid.  7) Digestion module according to claim 6 characterized in that it comprises in the upper part of the portholes (14) for viewing with light portholes (16) on the roof.  They allow you to see inside the module.  8) Digestion module according to claim 7 characterized in that each tube (60) comprises an archimedean screw (37) having the functions of brewer and product transporter.  These screws are controlled by geared motors (33).  9) Sella digestion module claim 8 characterized by the provision at the bottom of each path of a container (38) containing volcanic rock or alveolar synthetic material.  These elements (38) have the particularity of favoring the breeding of methanogenic bacteria.  10) Container according to claim 9 characterized in that it comprises an exchanger (39) for air conditioning the nest bacteria.  The heat transfer fluid enters and exits at (40).  11) Digestion module characterized by a tube (13) allowing the emptying of the methanisable material circuit.  12) Digestion module characterized by two tubes (2) used for the evacuation of the methane produced in each of the routes.  13) Anaerobic digestion chain characterized by the assembly of several digestion modules according to claims 1 to 12.  14) Anaerobic digestion chain according to claim 13 characterized by a grinder (21), a suction of modules (1) of the pumps (5) and (10) and an automatic centrifuge (22).  15) Variant of an anaerobic digestion module characterized in that the U-shaped path followed by the anaerobic substances is made up of membrane tubes (29).  They are welded to each other to form a sealed volume, inside which digestion takes place.  16) Digester module according to claim 15 characterized in that the calories necessary for digestion are provided by a heat transfer fluid circulating in all the tubes (29) supplied by the inlet and outlet collectors (30).  17) Digester module according to claim 16 characterized in that the materials enter (44), pass through a retaining valve (31).  They are raised to the entrance (36) by an endless screw and tube (32).  18) Digestion module according to claim 17 characterized by an outlet box (34) in the form of a siphon letting through the liquid but not the biomethane. 19) Digestion module according to claim 18 characterized by the addition of two screws (37) for mixing and advancing organic matter in the circuit.  20) Digestion module according to claim 19 characterized by the provision of baskets or containers (41) filled with volcanic rock used for cultivation and reserves of methanogenic bacteria.  These bacteria nests are hung on the internal walls of the module.  They sow the vegetable matter which bypasses them everywhere.  21) Digestion module according to claim 19 characterized by a variant of the transfer and seeding device.  Two mobiles (47) move alternately and vertically in each compartment of the digester, they contain aggregates (50).  22) Digestion module according to claim 21 characterized by pallets or valves (48) for advancing and mixing the product.  23) Continuous digester according to the claims  previous from 15 to 22 characterized in that each digestion module can be assembled one to the other, according to the figure (17).  This arrangement increases the capacity of each.