NL8101821A - Anaerobic manure fermentation plant for self-erection - has prefabricated modular trough sections with water lock channels for gas hoods - Google Patents

Abstract

The installation is intended for anaerobic fermentation of organic matter, partic. manure. It comprises a fermentation chamber with inlet for the manure and outlet for the effluent, a gas containment hood, and a water lock, forming a seal between the hood and the chamber. The installation is built up from modular units which each consist of a number of separate components and are assembled side by side in a horizontal row to form an oblong trough with a number of gas hoods. The peripheral water lock may consist of an upwardly open channel integral with the longitudinal sides of the unit sections and channels integral with the inlet and outlet panels at the two ends of the trough, whilst channel inserts are arranged at the joins between successive sections. Pre-fabricated modular components permit self-erection thus reducing initial investment. The design permits the use of a simple stirring mechanism as specified and enables cleaning unit by unit so that the usual 30 day re-start delay after cleaning is eliminated. Further advantages are those inherent in effective anaerobic fermentation including elimination of surface water pollution when spreading the effluent and avoiding loss of nitrogen.

Description

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Applicant: · Friedrich Jacob Johan Ogg in Nijmegen.

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Short designation: Device for fermenting organic material.

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The invention relates to a device for the fermentation of organic matter with an airtightly closed fermentation space, means for supplying the organic material to the fermentation space, means 10 for discharging the fermented material from the fermentation space, a gas cap and a water seal for sealing the connection between the fermentation space and the gas cap.

Such devices for fermenting organic material are known and are used in various embodiments, in particular for the fermentation of manure from pigs and cattle.

This known device has the drawback that it is not possible thereby to economically recover biogas from the organic material, which is the main function of such devices.

The object of the invention is to meet this drawback and to that end provides a device of the type mentioned in the preamble, characterized in that it is built up of modular units, each consisting of a number of separate elements and in horizontal built together.

Because the device according to the invention is built up from modular units, which in turn are formed by separate elements, it is possible to supply and transport the device as a kit, so that the farmer can take care of part of the build-up, enabling significant savings in construction costs to be achieved.

The device according to the invention is preferably designed in such a way that the water seal consists of a channel running around the fermentation space with a U-shaped cross-section, the water seal being connected to the modular units. ..........-..................

8101821 - 2 - * * adjacent to each other, is common to the modular units, where the water seal between the two modular units also consists of a U-shaped gutter, in which the respective walls of the gas caps of the modular units can be applied.

The modular units are preferably built up from a bottom plate and two adjoining side walls, the top part of the side wall also forming a wall of the water seal.

The device according to the invention is preferably built up from ferrous cement, although other materials, such as steel and polyester, can also be used.

Due to the horizontal arrangement of the device according to the invention, it also offers the advantage that it can be provided with a simple agitator, which contains a fence, guide means for the fence and pulling cables for pulling the fence through the organic material.

A float body is preferably attached to the fence.

Next, the device according to the invention will be described to the. from the drawings, in which:

Fig. 1 shows a perspective view of the device according to the invention;

Fig. 2 shows a partial perspective view of the device according to the invention;

Fig. 3 shows a perspective view of. the modular unit according to the invention;

Fig. 4 shows a partial cross-sectional view of a modular unit of the device according to the invention; FIG. 5 shows a partial cross-sectional view of the coupling of two modular units of the device according to the invention;

Fig. 6 shows a sectional view of a water seal; and FIG. 7 shows the agitator used in the device according to the invention.

When plants and other organic matter with an 8101821 ♦ * -3-.

If a certain temperature is brought to an enclosed space with the exclusion of oxygen, anaerobic degradation (methane fermentation) will take place, whereby the so-called biogas is formed, which consists of approximately seventy percent methane and approximately thirty percent carbonic acid.

In methane fermentation, three processes take place, which occur successively. First of all, hydrolysis occurs, in which insoluble organic substances are converted into soluble substances under the influence of certain enzymes. Acid formation occurs in the next step, which then takes place. The dissolved organic substances are absorbed in the cell and converted here with the aid of intracellular enzymes.

Finally, in the last sub-process, the products formed in the acid formation are converted into methane and carbonic acid by a group of strictly anaerobic bacteria (methane formers).

In the above-described process it is important that the acidity is very stable and preferably lies between 6.7 and 7.4. It is also important that the temperature is kept between thirty-two degrees C. and thirty-seven degrees C. and is kept at a constant value. Another important parameter is the carbon / nitrogen ratio, which is preferably about thirty. If this value is higher, less methane and more hydrogen is produced, if this value is lower, less methane and more nitrogen is produced.

The volume of the installation is determined by the time that the organic material (manure) must remain in the installation for optimal fermentation. This residence time can be between 15 and 40 days depending on the temperature.

An important advantage of fermenting organic material (thin manure) is that no contamination of the surface water takes place through the discharge of manure or over-fertilization. This makes it possible to achieve savings (through a reduced water board levy) of the order of ten percent of the construction costs of the device according to the invention.

Furthermore, it appears that when fermenting thin manure all 81018 2 1 -4-. .-

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Nitrogen is retained, which, unlike the usual methods, produces a nitrogen yield, the value of which can be estimated at ten percent of the construction costs of the device according to the invention.

5 When the manure is spread over the pasture in the normal manner, the animals are refused hay and grass, because their taste is adversely affected.

When fermented manure is used as fertilizer, this drawback does not occur, because the fermented manure is almost odorless. The fermented manure is also more easily absorbed.

Finally, an amount of gas is produced by the fermentation process, the value of which may be on the order of five ë. ten percent of the installation costs of the installation, depending on its dimensions.

Fig. 1 shows a preferred embodiment of the device according to the invention. This consists of a number of fermentation trays 18 with side walls 1 on which a water seal 2 is arranged. Gas caps 4 are provided on the trays, to which is connected a gas pipe 5, which opens into a collecting pipe (not shown). Two adjacent gas caps are fitted with a side wall, in the connecting element 3 of the water seal. To obtain the desired pressure under the gas hood, the installation can be equipped with a compensation mechanism for the weight of the gas hoods.

Since this mechanism is known and used in conventional gas containers, it is not further described here.

Fig. 2 shows in more detail the manner in which two modular units of the device according to the invention are assembled. Of importance here is the placement of the connecting element 3 between two modular units. Due to the large weight of the thin manure, which can be present in the installation, it is desirable to apply the device to foundations 8. When necessary, the side walls 1 can be fixed to the foundation 8 using bolts. or other fasteners. The seams between the various elements can be made gas-tight using a suitable grout 8101821 'f - 5. It is also possible to provide the elements with flanges with holes arranged therein and then assemble the units using bolts and nuts.

FIG. 3 shows a perspective view of a modular unit of the device according to the invention, in particular the supply element 6 being indicated with the diving partition 7. The discharge channel 13 (fig. 1) is designed in a corresponding manner. The level of the material to be fermented in the fermentation trays 1B is above the top of the opening in the diving bulkhead 7, so that an airtight separation is obtained. The material to be fermented is continuously supplied with the aid of the supply element 6 and can be continuously discharged at the discharge element 13 again.

FIG. 4 shows a partial cross-sectional view of a modular unit of the device according to the invention. Reference numeral 19 here denotes the bottom plate of the fermenter. The reference numeral 10 denotes the organic material (thin manure) present therein, while the reference numeral 9 denotes a floating layer which may consist of straw and coarser parts which are present in the manure.

Fig. 5 shows in detail a partial cross-sectional view of the coupling of two modular units 25 of the device according to the invention.

Fig. 6 shows a cross-sectional view of the water seal, showing that a side wall 11 of the water seal is a continuation of the side wall 1 of the fermentation vessel 18. Reference numeral 12 indicates the other side wall of the water lock. In order to save material, the cross-sectional area of the side walls 11 and 12 of the water seal 2 decreases upwards.

Finally, Figure 7 shows a stirrer which is used in the device according to the invention. Two guide cables 16 and 17, which are arranged in the longitudinal direction in the fermentation trays 18 of the device according to the invention, are shown here. On these guideways 8101821-6-6 cables 16 and 17, a fence 14 can be moved in the longitudinal direction of the device. This is provided for in. a pulling cable 18. The fence can be provided with a float 15 and have such a weight that it automatically assumes a vertical position. The agitator can be driven by an electric motor or other suitable means.

The optimum temperature for the fermentation process is between thirty degrees C. and forty degrees C. To this end, it is necessary that the fermentation tanks are internally heated, which requires a separate heating installation. It is not shown in the drawings.

Furthermore, it may be desirable to provide a heat exchanger in the discharge element 13 to heat from the fermented manure. win back.

15 Because the temperature is constant within + 1 degree C. it must be kept that the entire device is provided with an insulating layer. Nor is this insulation shown in the drawings.

A further advantage of the device according to the invention is that during cleaning it is not necessary to shut down the entire installation. This cleaning may be necessary to remove sand and gravel, which will accumulate on the bottom in the longer term. The level of the organic material 10 in the fermentation trays 25 can be raised above the bottom of the connecting elements 3. Then one of the gas domes 4 can be removed and baffles can be arranged under the elements 3. The manure present in the fermentation tank 18 to be cleaned can optionally be transferred to the other fermentation boxes 30. After cleaning, the baffle plates can be removed and the gas cap replaced.

In this way it is achieved that the long start-up period (about thirty days) during cleaning can be avoided.

An important function of the agitator shown in Fig. 7 is to bring about contact between the microorganisms and the substrate (the thin manure). The agitator additionally maintains a uniform temperature in the digestion chamber and prevents and disturbs buoyancy and settling layers, thereby preventing the active tank contents from being greatly reduced by the gastight buoyancy and settling layers. . Stirring also prevents the bacteria from being poisoned at some point by their own waste materials.

In the device according to the invention, the gas storage takes place in the gas domes 4. When the storage space under the gas domes 4 is not sufficient, a separate gas clock 10 can be used, or optionally a separate gas bag. The gas can also be stored in gas cylinders after compression.

The device according to the invention is preferably made in ferrous cement with a mesh reinforcement in combination with ordinary reinforcing steel. Here, a wall thickness of two two three cm can be used, while the bottom has a thickness of about five three six cm. Due to the small wall thickness, a considerable weight saving is achieved (about forty percent of the weight of a comparable construction in concrete). This makes it possible to manufacture the installation from individual elements in the factory and then transport them to the construction site, where the elements are assembled. Ferrous cement also has the advantage that it is moisture and waterproof and also resistant to corrosion. An epoxy coating can be applied to the ferrous cement, while penetration of moisture into the construction and corrosion of the reinforcement do not occur.

The modular units shown in the figure have a volume of about thirty m with a gas storage of about sixteen m3. For this, a manure / waste quantity of approximately one m3 per day is possible per modular unit. This is an amount of manure, which is produced by a livestock population of approximately sixteen and twenty livestock units. The estimated annual yield of a modular unit is approximately seven thousand m3 of gas, of which approximately two thousand ra3 is required to keep the process up to temperature.

Naturally, the invention is not limited to the exemplary embodiment shown in the figure. So it is at ____ -Λ 8101821 -8-.

example possible to design the refreshment tanks as a half cylinder as well as the gas domes, whereby the water seal is then built up as a separate element.

It will be clear to the person skilled in the art that many variations of the principle shown are possible. These variants are considered to fall within the scope of the invention. The device according to the invention has the further advantage that a large ground surface can be selected in places with a soft surface, so that no driving is necessary. - 8101821

Claims (7)

1. Device for fermenting organic material with an air-closed fermentation space, means for supplying the organic material to the fermentation space, means for discharging the fermented material from the fermentation space, a gas cap and a water seal for sealing the connection between the fermentation space and the gas hood, characterized in that the device is built up of modular units, each of which consists of a number of separate elements and are built together horizontally. 2. Device according to claim 1, characterized in that the water seal consists of a channel running around the fermentation space with a U-shaped cross section, wherein the water seal, where the modular units adjoin each other, is common to the modular units. Device according to claim 1 or 2, characterized in that the water seal between two modular units consists of a U-shaped gutter, in which the respective walls of the two gas caps of the modular units can be arranged. 4. Device as claimed in any of the foregoing claims, characterized in that the modular units are built up from a bottom plate and two adjoining side walls and that the top part of the side wall also forms the wall of the water seal. 5. Device as claimed in any of the foregoing claims, characterized in that the means for supplying and the means for discharging the organic material comprise a diving bulkhead with an attached water seal and a supply tray and a discharge tray, respectively. 6. Device as claimed in any of the foregoing claims, characterized in that it furthermore comprises a stirrer, which comprises a fence, guide means for the fence 35 and pulling cables for pulling the fence through the organic material. 7. Device as claimed in claim 6, characterized in that 8101821 GO O 00 ro