FR2478940A1 - Anaerobic fermentation plant to produce fuel gas and fertiliser - has continuous digester with mechanised feed and drainage for discharged material - Google Patents

Abstract

An installation for anaerobic fermentation of organic waste comprises a reception sump for raw waste, a mechanical feeder to transfer material from the sump to a gas-generating digester vessel. The digester vessel discharges fermented material to a separator where liq. is drained from material intended for use as organic fertiliser. The mechanical feeder pref. comprises a screw conveyor, a paddle conveyor or a pump. Within the digester vessel, fermenting material is pref. agitated by a rotor, by a recycling pump or by a recycling screen conveyor. Fermenting material can be heated by electricity, by gas or by solar energy. The separator for draining the fermented material is pref. a screw conveyor with performed screen housing or a dewatering mesh band conveyor. Gas generated in the digester is pref. passed via a non-return value to a gasometer. A fraction of the gas is recycled by a compressor for reinjection into the fermenting material. Used for prodn. of a fuel gas and an inoffensive, reasonably dry fertiliser. The p plant operates continuously and without manual labour. It can be adapted for large scale operation and equipped with automatic controls. Suitable for farm or factory installation.

Description

The subject of the invention is a digester by anaerobic fermentation of organic materials, an installation for recovering organic materials, an installation for gas production, gas storage, gas treatment, gas distribution and dry matter separation. and humid digester effluents.

 At present, there are unit-designed installations for which the automation of the process of loading, unloading and preparation of the product to be transformed is not taken to an extreme and there are still operations either manual or in front be controlled by a human eAtre. In addition, the quantity of digested product recovered at the outlet from the digester is substantially equal to the quantity introduced into the digester so that the owner of such an installation is faced with the very important and expensive problem of storage, spreading of large amount of product. These users do not always have the land areas available and necessary for this spreading. Finally, the digested product is not entirely deodorized so that its spreading or storage can cause nuisance.

The treatment process as a whole, object of the invention, makes it possible to avoid these drawbacks. It can be applied to the production of gas and solid or pasty fertilizers on farms, treatment plants and any other site provided with organic matter.

The object of the invention is to provide simple means of use and easy implementation, a new digester, a new installation allowing the continuous use of the process described below.

The aim is achieved by the fact that the digester consists of an enclosure communicating in its lower half to the recuperator and in its upper half to the installation for the treatment of effluents and to the gas distribution storage station. The aims and means are also achieved and described without implied limitation with regard to the appended drawings in which there is shown in FIG. 1: a schematic view in vertical section of an embodiment
of the invention in fig. 2: a variant of the effluent extraction mode in fig. 3: a variant of the method of extracting the effluents in FIG. 4: a variant of the method of extracting the effluents in FIG. 5: a variant of the method of brewing the materials stored in
the digester in fig. 6: a variant of the method of brewing the materials stored in
the digester in fig. 7: a variant of the method of brewing the materials stored in
the digester in fig. 8: a variant of the method of brewing the materials stored in
the digester in fig. 9: a variant of the method for reheating stored materials
in the digester in fig. 10: a variant of the method of reheating stored materials
in the digester in fig. 11: a variant of the method for reheating stored materials
in the digester in fig. 12: a variant of the reheating mode of the stored materials
in the digester in fig. 13: a variant of the method of reheating stored materials
in the digester in fig. 14: a variant of the loading mode of the digester in FIG. 15: a variant of the loading mode of the digester in FIG. 16: a variant of the effluent treatment mode in fig. 17: a variant of the effluent treatment mode in fig. 18: a variant of the effluent treatment mode in FIG. 19: a variant of the effluent treatment mode in fig. 20: a variant of digester in fig. 21: a view in horizontal section of the digester represented in FIG. 1 in FIG. 22: a view in horizontal section of a variant of digester in FIG. 23: a view in horizontal section of a variant of digester in FIG. 24: a digester battery setting device in fig. 25: a variant of the gas storage in fig. 26: a variant of the gas storage in fig. 27: a schematic view of a security device
According to a first variant, the installation is made up of a prefix 1 for kneading, homogenization with or without the addition of juice, water or other organic matter in which an aerobic pre-fermentation can take place. A pump 2 sends the product through 'A pilot valve 3 in a thermally insulated tank 4. The biological process of digestion begins and the three main phases follow one another to give at the end of the reaction a digested product which is pushed towards the extraction point 5 by a new injection of material to be treated and pours out through a siphon 6 on a battery of decantation areas 7 whose surface will be in relation to the quantity of material and the supply of which can be rotated.

 The solid products 8 are deposited on the bottom while the liquids 9 are discharged into a sump 10 or any other means of evacuation. The rotation envisaged above makes it possible to isolate a settling area with a view to recovering the solid products 8 by traditional loading means.

 The methanization phase, which is very sensitive to the environment, requires keeping organic matter at constant temperature by means of a device with heating resistors, supplied by an energy source 12 and subject to control and monitoring. regulation not shown in this figure but can be obtained by any commercial means.

The mixing and activation necessary for the proper functioning of the digestion is done by injection into the heart of the recovered gas tank -by the pipe 13 passing through a non-return safety valve 14, sto key in a gasometer 15 , then reinjected under pressure by a pipe 16 passing through a compressor 17. The excess gas is evacuated through the valve 18 to supply any device operating on gas. The devices mentioned above are regulated electrically. Other variants of embodiments that can be integrated into the installation described above are presented - In fig. 2 on which an extraction screw 19 electrically driven and placed in the upper part of the tank 4 so that the outlet 20 is not in direct correspondence with the gas recovery zone.

 This screw 19 ensures the extraction of the digested materials.

- In fig. 3 another variant of the extraction mode of FIG. 2 for which the screw is replaced by a vane extractor 21 forcing the materials at 22.

- In fig. 4 another variant of the extraction mode in which a pump 23, which may or may not be provided with a kneading or grinding process, ensures the extraction.

- In fig. 5 a variant of the activation mode in which a paddle stirrer 24 ensures mixing.

- In fig. 6 another variant of the activation mode in which a pump 25 sucks the effluent to reinject it at another point of the digester thus creating a transfer of material.

- In fig. 7 another variant of the activation mode shown in FIG. 6 in which the direction of delivery of the pump 25 is reversed.

- In fig. 8 another variant of the activation mode in which a screw 26 sucks the effluent through the orifice 27 and discharges it at 28.

 - In fig. 9 a variant of the mode of heating of the materials being digested in which a resistor 29 heats the product passing through a pipe 30 which may be the same as that used for the activation described in fi. 6 and 7.

- Fi nally. 10 another variant or mode of heating shown in FIG. 9 in which a coil 31, preferably containing hot water, breaks the resistor 28 of FIG. 9.

The fuel capable of being, inter alia, the gas produced by the installation, or else commuted in FIG. 11 in which the solar energy heats the liquid circulating in the coil 31.

- In fig. 12 another variant of the heating mode in which an immersed resistor 32 supplied by a source 33 and a contact 34 maintains the temperature and can ensure mixing of the product.

- n fig. 13 another variant of the reheating mode in which resistors 35 are embedded in the thickness of the wall 36 of the digester.

- In fig. 14 a variant of the filling mode of the digester in which a screw 37 pushes the material introduced at 38 through a non-return valve 39 in the digester 4.

- In fig. 15 another variant of the filling mode shown in FIG. 14 in which the screw is replaced by a piston 40, the material being injected at 41.

- In fig. 16 a variant to the mode of separation of dry and wet materials from the digester effluent into which the material to be treated arrives by a distribution chute 42 on an openwork carpet 43 which can be arranged horizontally or circularly. The material transported on the carpet is pressed on it by a series of flaps or rollers 44. The solid residue is poured at the end to form a reserve of fertilizing material4U.

The residual water is collected at 46 and then discharged into a pit, sump, sewer system 47 or used as an irrigation product.

- In fig. 17 another variant of the method of separating dry and wet materials from the effluent in which the material to be treated is introduced into an perforated cylinder 43 by a pipe 49, a screw 50 Far its rotation ensures the transfer, the pressing of the material and separating the solid products recovered at 51 at the end of the cylinder. The water is collected by a device 52 and then poured into o3.

 -In fact. 1S another alternative to the separation of sects and wet matter from the effluent into which the product to be treated is poured into an oxygenation station 54 by a pipe 55. A drum 56 ensures oxygenation. By overflowing the product passes into a settling tank 57 through the pipe 58. The lightly laden sludge from the tank 57 is recycled into the oxygenation tank 54 by means of a pump 59 through a valve 60, the sludge loaded from tank 57 is propelled into a storage tank 61 by the same pump 59 and through the same valve 60. The residual water recovered at 62 is sent to a recovery network such as sump, basin, etc.

- In fig. 19 another variant of the method for separating dry and wet materials from the effluent in which the product to be treated arrives tangentially at 63 in an enclosure 64 and with a pressure generated by a pump 65. The liquid having acquired a rotational movement passes through a perforated cylinder 66, descends into a column 67 and the particles in suspension are under the effect of the centrifugal force rejected against the wall. At the bottom of column 67, a deflector 68 breaks the flow of liquid. The solid particles 69 are deposited in an enclosure 70 while the purified liquid rises in the center of the column 67 towards the outlet 71.

A door 72 allows the extraction of solid materials.

The series connection of such a device can be envisaged in order to improve the purity of the final liquid. I1 is possible to automate the extraction of solids by adding on the door 72 an automatic opening command.

- In fig. 20 a variant of digester in which the tank 73 is horizontal and has a wall 74 delimiting a volume 75 in which the anaerobic transformation takes place and a volume 76 in which the re-digested product is poured, is stored and is evacuated by the bottom of the digester at 77. The two compartments 75 and 76 are of equal volume. It goes without saying that all the tanks envisaged in these writings may include inspection, cleaning, emptying or sampling orifices placed in the places suitable for these functions. It goes without saying that the heating and mixing operations are carried out in compartment 75.

- In fig. 21, 22 and 23 of variants of digester sections which can be adapted either to the manufacturing techniques or to the digestion yield in the case of vertical digesters as in fig. 1 or horizontal as in fig. 19. The same goes for the composition of the materials making up the tanks, such as polyester, steel, concrete, etc.

- In fig. 24 a battery arrangement of digesters 78 and 79 the number of which cannot be limited and the supply of which is made by only one of the apparatuses 80 described previously in FIG. 1, 14 and 15. The distribution is done through a multi-way valve 81 distributing the product in a single digester at a time to allow control of the supply.

 - In fig. 25 a variant of the gas storage mode in which a flexible tank 52 incidentally protected from bad weather or shocks. This tank is fitted with all the connections necessary for gas exploitation.

- In fig. 26 another variant of the gas storage mode in which a gasometer 83 receives the gas produced and ensures by the weight of the bell 84 a constant pressure of the stored gas.

- In fig. 27 a protective device connects to the supply line 85 of the gasometer 86. The body 87 receives a valve 88 held in its housing by a spring 89 calibrated at a pressure equivalent to the pressure tolerated in the circuit 85. In the event of removal, the valve 88 lifts and lets pass the gas which will be burned in a flare 90.

Claims (7)

REVEgDICATI0Ns 1. Installation for producing organic gas and for separating dry and wet matter dimensions of the digested product associated with a pit (1), connected to a tank (4) itself connected to a storage and distribution apparatus gas (15) and an organic waste separation device (b). 2. Installation for producing organic gas and for separating the digested products according to claim 1, characterized in that the means for recovering organic matter in the pit (1) and for transferring to the tank (4) are done automatically and regularly by one of the methods described above in the appended figures. 3 installation for producing organic gas and separating the digested products according to claim 2, characterized in that the å- gesteur (4) comprises an anaerobic fermentation chamber in which the product injected in an upward movement and is discharged by pouring or all other automatic means described above in the appended figures. The digesters can be mounted in batteries according to the appended figures. 4. Installation for producing organic gas and for separating the digested products according to claim 3, characterized in that the stirring means according to the appended figures is an automatic means.  5. Installation for producing organic gas and for separating the digested products according to claim 4, characterized in that the reheating means according to the appended figures is an automatic adjustable means.  6. Installation for producing organic gas and for separating the digested products according to claim 5, characterized in that the means for treating the effluents according to the appended figures is an automatic means.  7. Installation for producing organic gas and for separating the digested products according to claim 6, characterized in that the gas storage means comprises reservoirs according to the appended figures. S. Installation for producing organic gas and for separating the digested products according to claim 7, characterized in that the protection means of the installation comprises a device described according to the appended figures.