JPH0137998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION SUMMARY OF THE INVENTION An improved anaerobic digester for producing methane gas from waste biological material comprises equipment for continuously feeding biological material into the digester and for continuously advancing and agitating the biological material. and a closed system consisting of equipment for passing successive stages in this equipment, equipment for continuously collecting the gas produced, and equipment for continuously discharging the spent biological material from the equipment for use as fertilizer;
Other embodiments include a long passage in a plurality of parallel short lengths of integrally cast troughs, each of which has a plurality of corresponding semi-cylindrical shrouds and ends of the tank so formed. and an end piece having a U-shaped connection therebetween.

(Industrial Application Field) The present invention generally relates to a combustible gas generator,
In particular, it relates to an improved anaerobic digestion device.

BACKGROUND OF THE INVENTION Anaerobic fermentation of waste has been used for over 100 years, and says, ``This clean, renewable source of energy can supply most of the energy used in agricultural operations, while also providing limited It is estimated that the use of land to produce biomass for fuel could meet the energy consumption of the United States. The above information is
D. G. J. et al., “Biological Transformation of Agricultural Wastes for Pollution Control and Energy Conservation” [Published September 1976, Cornell University Final Report Contract ERDA-NSF-
Obtained from the abstract of No. 741222A01. This report discloses various types of equipment for digesting organic waste, including semi-continuous feeding, such as silo equipment, fully mixed equipment, "continuous" feeding equipment or Miyunchen type equipment, batch loading equipment,
A plug flow device or a device consisting of a permuted combination thereof is used, whether heated or unheated.

The following U.S. patents have been dealing with the digestion of organic waste for over 100 years, and some of them have disclosed gas production: U.S. Pat. Patent No. 39472 discloses the production of gas in the processing of human waste; U.S. Pat. U.S. Patent No. 1,543,154 to CB Fox et al., dated June 25, 1934, discloses the atomization of organic waste and its fermentation; discloses the anaerobic production of methane and thermal selection of bacterial strains, and U.S. Pat. U.S. Pat. No. 3,241,943 to S.G. Bystrom, dated March 22, 1966, discloses a gas-generating waste treatment apparatus using a plurality of containers in stages. U.S. Patent No. 3,890,129 to F.B. US Pat. No. 4,040,953 discloses an anaerobic device for methane production with a two-stage device.

A. Makijiani et al. [“Energy and Agriculture in the Third World”, Boehringer Publishers, not yet available today, expected to be available in 1974 or later]
includes a separation step for digestion, a heating means, a vertical mixing device, a linear discharge plug flow device with different digestion steps at different points along the length of the channel, and a mixing step in the channel device. The problem of gas generation from organic waste including the potential is being investigated.

The general requirements for the economical production of methane from waste organisms can be summarized as follows with reference to the sources listed below: 1. Mixing: Methane production involves continuous mixing of waste slurries. (Byström patent and Chiester patent).

2 Heating: Methane production is achieved by maintaining the slurry mixture at 30° to 35°C for mesophilic digestion (Byström and Chiester patents) and at 50° to 60°C for thermogenic digestion (Jewel et al. ) will be optimized.

3. Continuous Flow: Although a number of batch digesters have been patented and are in use, the labor costs and health and odor issues of the batch process make continuous flow highly desirable (Jewel et al.).

4 Minimum Dimensions: Digester material and equipment costs increase approximately linearly with size. Therefore, it is desirable to limit waste dilution for minimum cost.

5. Simplicity: The engineering level of the operation of a fire extinguisher cannot be ignored. Therefore, the simpler the device, the better.

6 Reliability: The extinguisher and its support equipment must be able to operate reliably even under adverse conditions. Typical unintentional contaminants include stones, wood chips, gravel, etc. The extinguisher and loading and evacuation equipment (such as pumps) must be able to handle these foreign bodies with minimal risk of destruction (Jewel et al.).

Furthermore, the extinguisher must be able to operate under various environmental conditions, especially in cold climates.

(Problems to be Solved by the Invention) Although the digestion devices developed to date have one or more of the above requirements, none of them solves all of the requirements at the same time. Early patent documents (such as the Henkelekian patents of Fitz, Erie, and Focks) describe batch digesters, but these only indicate that methane can be produced from farm and municipal waste. . The Fox et al. patent recognizes the benefits of pre-grinding waste. Henkelekian's patent describes a batch digester that uses a portion of the methane produced to heat the tank. The MacDonald patent describes a continuous flow digester (large size) that requires significant dilution.

The Orth patent describes a continuous flow digester (using a diluted slurry) with two stages. Continuous mixing is achieved in the first stage. McDonald's patent describes a continuous feeding device with several chambers for use on farms. These last two types of devices, although approaching a total solution, have several drawbacks. Both use diluted slurries to minimize pumping/mixing problems, resulting in significant increases in equipment volume and cost. Both also suffer from difficult maintenance problems in the event of pump failure, and both require periodic interruptions in operation and cleaning to prevent build-up of foreign material.

Makijani's literature states that linear discharge digesters are the best candidate for cost reduction. In his design, the long channels create nearly plug flow (also recommended in the Cornell University study). However, difficulties can be expected in maintaining flow in this type of device.

In short, it is believed that no device has been disclosed heretofore that provides the advantages of the device aimed at by the present invention. It is therefore an object of the present invention to provide a device for the production of gaseous fuel by anaerobic digestion of waste biological matter, which device combines the efficiency advantages of multi-stage digestion with the simplicity of a single-stage device. It also provides reliability and performance suitable for long-term trouble-free use in primitive regions or regions where extreme efficiency and highest quality of methane gas production are the main goals.

It is also an object of the invention to provide such a device which is always substantially self-cleaning and self-removal of non-digestible materials such as stones.

Furthermore, it is an object of the present invention to provide the above-mentioned method capable of efficiently treating living organisms or wastes at both high and low solids concentrations and at medium and high temperature ranges. The purpose is to provide equipment.

SUMMARY OF THE INVENTION In summary, the present invention is directed to a closed linear device that advances waste organic matter at a constant, slow rate from a continuous supply at an inlet to a continuous discharge at an outlet. A central screw conveyor provides continuous mixing and achieves a uniform progression of the digestion stages along the apparatus, and also makes it possible to simultaneously recover the gas produced.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings (like reference numerals are used for like parts).

FIG. 1 shows a device 1 of the simplest embodiment of the invention.
0, which is an improved device for anaerobically digesting organic matter to produce methane gas and producing useful solid and liquid fertilizers from waste organisms.

The apparatus of this embodiment is composed of a feeding device 20 and a digestion device 22. The feeding device or storage tank is a means for continuously receiving living matter or organic waste and feeding it into the device, and the feeding tank 2
4, which supply tank preferably has a sealable top 26 and a funnel-shaped bottom 28.
A coil piping 30 or an equivalent thereof is provided therein for heating the biological body B with water vapor or other thermal fluid. If desired, this water vapor can be forced to flow upward through the organism. The device is continuously loaded as the organisms move down by gravity to the feed end of the first conveyor 32, which is preferably a generally horizontal screw conveyor. The first conveyor is preferably a sealed tube, sealed at a first end in a conventional motor drive 34, sealed at a collection point from the tank and at a second end, an outlet into the digester. is sealed.

The digester includes a cylindrical tank means or chamber body 36 and first and second end caps 38, 40 for continuous treatment of organic matter throughout the device. The digester inlet or feeder extraction section 42 is preferably located at the top of the first end of the body. From that point, a second screw conveyor 44 is mounted axially within the body and has a length and diameter that substantially fills the body so that entrained organisms are uniformly distributed over the length of the body. To move efficiently and simultaneously with speed.

The motor drive 46 is the same as the first and proportionally rotates the second screw conveyor at a low speed.

The screws of the second conveyor are advantageously provided on the shaft 50 of the screw means provided externally to the first end cap.
It can be rotated by a worm gear 48 mounted on the worm gear 48 and driven by a worm 52 mounted on the shaft of a motor 46, which can be an electric motor having a frame attached to the end cap. In this way, the organism can be isolated from the drive machine.

As the organisms move along the body through this seal, they are continuously mixed and fermented, releasing gases (mainly methane and carbon dioxide) that are sealed and spread along the length of the body. Along hole 54
is collected into the manifold 56 via the pipe 5
8 to a conventional gas storage tank (not shown).

The speed and guidance of the screws are such that the organisms are moved into the device according to a schedule adopted according to well-known principles to produce the maximum amount of methane. The most efficient length of time is determined by temperature, pressure, biological fluid proportions and other components, and other known parameters.

Fluids (eg, water and/or steam) can be added to the device to aid in processing, and the body can also be continuously heated and insulated to retain heat, as described below. At the second end cap, the device continuously discharges an effluent consisting of solid and liquid residues of biological matter and fluids associated with the process.

The outlet 60 for the effluent is preferably located at the top and forces out the effluent by the pressure exerted by the screw of the device. Foreign objects, such as rocks, are removed from the lower part or debris outlet 62, which includes a rear chamber 64 for debris accumulation. This outlet can be opened at predetermined intervals to remove contaminants manually or automatically.

The device can rest on the legs 66 or any solid foundation, such as a cast foundation.

FIG. 2 shows further details of the device. The second screw means 44 has bearings supporting it and can be present in the tubular body or in the end cap. The bearing 68 in the first end cap 38 is shown here as a conventional thrust bearing adjacent to a conventional gland packing 70 to seal rotational movement of the shaft and prevent leakage.

As a suitable feature, a motor 3 for driving the screw
4' may exist externally, but its motor shaft 72
extends through a conventional gland to the inside of the end cap, where the worm 52' at the end of the motor shaft tangentially engages a worm gear 48' fixed to the screw shaft 50.

This FIG. 2 further shows a gas collection device with apertures 54 in the top of the cylindrical wall of the body 36, and a manifold 54 overlying them.
6 and piping 58 to guide the gas to the storage section.
The top of the second end cap 40 has an effluent outlet 6
0 and a tubular passageway are provided to direct the effluent to a storage area, and a debris collection port 64 and a discharge port 62 are provided at the bottom of the second end cap. The screw bearing 74 and gland 70' in the second end cap may be similar to those in the first end cap.

FIG. 3 shows a suitable arrangement by which a fluid, such as steam or pressurized water, may be introduced into the digester through a conventional rotary seal 76 and into the end of the screw shaft 50'. The screw shaft has an axis bore 78 for this purpose. Steam or water flows through the holes 80 in the bearing 68 to constantly flush biological slurry from the bearing, facilitating operation and reducing maintenance requirements. The fluid itself can act as a greaseless bearing lubricant, and also acts as a heating agent and diluent for living organisms. Furthermore, for the latter two purposes, additional fluid can also be discharged via additional radial holes 82 in the bearingless screw shaft.

FIG. 4 shows in detail another apparatus for cleaning bearings 84, in which fluid flows through holes 86 in the fixed structure supporting the bearings. The bearing is cleaned by connecting the bore to a pressurized source of fluid, indicated by P and the arrow, and to grooves 88 forming a ring at each end of the bearing.

FIG. 5 shows a loop network 90 of pressurized fluid passages as a pattern in the wall of the body 36'.
These can have an arrangement consisting of a ring-shaped groove 91 and a plurality of stringer holes 93, through which the heating fluid is uniformly distributed and flows. The extinguisher body, the hole, and other parts of the device are provided with an insulating material 92 on the outside to help retain heat.

FIG. 6 shows a typical spider support 94, which is used along the length of the second screw conveyor means, on each support surface 9 of the screw shaft.
I support 6. They can also be assembled as spiders at the ends and/or in the middle if desired.

Preferably, each spider includes a ring 98;
The ring is axially oriented with respect to the bore of the body when mounted and supported on the inner wall of the body by three radial legs 100 integral therewith. leg,
In particular, the ends of the two lower legs can be embedded in the body or attached to it by screws. It is also clear that, according to custom, the ring can consist of two half-rings, which can be removably screwed and assembled on the bearing of the screw conveyor. At each spider section installation location, the screw section of the screw conveyor is interrupted, but the interrupted screw section rotates in close proximity to the spider on each side of the spider, thereby applying the desired shearing force to the biological body. Push into the gap in the spider.

FIG. 7 shows a second embodiment 700 of the device of the invention.
The base portion 766 of the body is preferably made of a concrete member and is provided with a plurality of upwardly concave semi-cylindrical portions 767. A plurality of matching complementary half-cylinder covers 736 are provided to cover the half-cylinders and form a cylindrical tank or chamber body for each screw 744 of the conveyor mechanism. Each cover has the same length as the trough and is attached to the base by cement or by screws or other suitable means. A row of holes 754 along the top of these allow gas to flow upwardly and into a reservoir via a manifold 756 and piping 758 also mounted on the cover.

The end caps 738 and spiders 794 can be attached as before, except that the devices can be connected in series or series-parallel using U-tube connections 759 that join adjacent ends of the bodies.
The U-tubes may be metal or heavy-walled elastic of conventional composition, the entire tube may have the same diameter, and may be attached by screws or cement. The drive for the shaft can also be provided in the U-tube through the gland packing 770. The other connections and the driving and operation of these economic devices are similar to those described above.

It is also clear that, if desired, a cast base can be provided to align multiple devices and provide multiple drives from a single power source by known mechanical connections, and furthermore, the low rotational speeds and cover construction provide safety benefits. It is also clear that both reliability and reliability can be obtained.

The methane gas produced can also be used to power on-site diesel generators. Waste heat from the diesel can also be used to heat both the feed fluid and the temperature maintenance fluid for the generator.

Small acumulators of conventional design can be used in the gas collection piping to separate the various components according to well-known principles. CO ₂ can be removed by conventional bubble chamber or known membrane technology. However, such removal is not necessary.

It will be appreciated that the end bearings of the second screw conveyor may be mounted to the end caps, as well as that various other design changes may be made without departing from the spirit of the invention. Debris can also be removed from the extinguisher using a conventional gate valve.

Experimental Example 100 dairy cows produce approximately 154 cubic feet (4.36 m ³ ) of manure per day. Using a hydraulic residence time of 10 days, the volume of the mesophilic digester would be 1540 cubic feet (43.6 m ³ ) without dilution. It is 10 feet (3 m) in diameter and long
20 feet (6.1m) (volume 1570 cubic feet)
(44.6 m ³ ) of gastrointestinal tract and is staged, yet allows small dilutions. The structure of the digestive tube can be cement, fiber reinforced polypropylene, fiberglass or metal.
End caps can be molded or cast from similar materials. The bearing insert and flange plate can be made of stainless steel and embedded directly into the casting or molding, and replaceable bearing inserts are also contemplated. The auger can also be constructed using an aluminum or steel substrate covered with a thin layer of glass fiber. A gas accumulator can also be made separately and bolted onto the top of the extinguisher, using a non-reactive seal such as Teflon.
The supply price for this part is estimated to be $20,000 or less, depending on the final materials chosen for construction. This price includes the drive motor, feed tank and gas pump. 154 cubic feet (4.36 cubic feet) per day
m ³ ) contains 1007 lbs (456.8 Kg) of volatile solids. Using a 10-day HRT (hydraulic retention time), a 40% reduction in volatile solids occurred, resulting in 7300 cubic feet (206.7 m ³ ) of methane/CO ₂ per day.
(produced at a ratio of 1.86) and the calorific value is expected to be 650 BTU/ft ³ (5785 Kcal/m ³ ). Therefore, in total per day
4,750,000 BTU (1197,000 Kcal) or 198,000 BTU (49,896 Kcal) per hour would be obtained. The peak power load on such farms is about 15KW and the average load is 6KW. The estimated maximum power required to operate this digester and pump is 1.3 horsepower or 1.0 KW. Therefore, a 15KW diesel driving a 90% efficient alternator would meet the farm's power needs. about
Operating at an average load of 7KW (average 6KW for the farm plus 1.0KW for the digester) the diesel will be approximately 25% efficient. A waste heat boiler operating at 50% efficiency generates approximately 18 pounds of 5 psi steam per hour, which is sufficient to fully heat the digester and feed, and surplus steam is available. At average load (7KW), the diesel
Consumes 105430BTU/hr (26568.4Kcal/hr),
90000BTU/hr (22680Kcal/hr) of surplus gas remains. The diesel is estimated to cost $8,500 and the gas processing and storage equipment is estimated to cost $100,000.
Total equipment cost is approximately $30,000. 1 million BTU
The value of surplus gas produced at $2.50 per (252,000 Kcal) is $1,800 per year. The value of electricity in excess of the digester demand is $3720 in total annual revenue.
1,980 dollars (assuming 4 cents per 1KWh).

The stable effluent from the digester, which is nearly odorless, contains approximately 2.0 tons, 0.9 tons, and 1.7 tons of nitrogen, phosphorus, and potassium, respectively, on an annual basis, which is equivalent to 30 acres (12.1 hectares) of corn. (without crop rotation) and is worth about $2000 per year.

Total return on investment is $1800 plus $1980 plus per year based on current energy prices
2000 dollars or equal to 5780 dollars. this is
It would result in a simple amortization period of 5.2 years.
Further analysis uses the following assumptions: Investment amount $30,000 Depreciation rate 15% First year return $5780 Annual operating costs $500 Energy appreciation rate 10% Equipment life 15 years Iterative economic analysis indicates that this investment will be amortized over 2.3 years period and the return on investment is 36%.

With a high temperature digester, the size and therefore the capital is reduced. Although detailed data on high-temperature digestion are not yet available, it is estimated that digester costs will be reduced by as much as $8,000, which would reduce the potential simple depreciation to less than two years.

Although the present invention has been described with reference to examples, it should be understood that the present invention is not limited to these examples and that various design changes can be made within the scope of the present invention.

(Effects of the Invention) The anaerobic digestion device according to the present invention combines the advantages of efficiency of multi-stage digestion with the simplicity of single-stage digestion, and is suitable for use in primitive areas or with extremely high efficiency in methane gas production. It is possible to provide equipment with reliability and performance suitable for long-term trouble-free use in regions where the main goal is the highest quality.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the device of the invention in a first embodiment, FIG. 2 is a partial vertical sectional view of the device according to the first embodiment, and FIG. 3 is a partial detail showing the ends of appropriate accessory devices. 4 is an enlarged detailed sectional view of a suitable bearing arrangement; FIG. 5 is a partial perspective view of a suitable accessory; FIG. 6 is a perspective view of a structural spider member; FIG. 7 is a perspective view of a second It is an exploded perspective view of an example. 10... All devices, 20... Supply device, 22...
Digestion device, 24... Supply tank, 26... Sealed top, 28... Funnel-shaped lower part, 30... Coil piping,
32...first conveyor, 34...drive motor, 3
6... Chamber body, 38, 40... End cap, 4
2... Supply port, 44... Second screw conveyor,
46... Drive motor, 48... Worm gear, 5
0... shaft, 52... worm, 54... hole, 5
6... Manifold, 58... Piping, 60... Discharge port, 62... Debris discharge port, 64... Rear chamber, 6
6...Leg, 68...Bearing, 70...Gland, 74...Bearing, 76...Rotary seal portion, 80...Hole, 82...Hole, 84...Bearing, 86...Hole , 88... groove section, 90...
Loop mesh, 91...Ring groove, 92...Insulating material, 93...Stringer hole, 94...Spider support, 96...Support surface, 98...Ring, 10
0... Leg, 700... Device, 736... Semi-cylindrical cover, 738... End cap, 744... Screw, 754... Hole, 756... Manifold, 758... Piping, 759... Connection, 766
...Base, 767...Semi-cylindrical part, 794...Spider, 770...Ground.

Claims (1)

[Scope of Claims] 1. A device for anaerobically digesting organic matter to produce methane gas, which comprises a continuous processing means consisting of a horizontally arranged cylindrical tank, and a screwdriver mounted in the tank in the axial direction. a conveyor means, an organic inlet defined at a first end of the cylindrical tank, and an outlet defined at a second end;
The organic matter supply tank, a closed screw conveyor means for continuously supplying the organic matter from the supply tank to the organic matter supply port, and a motor drive that continuously rotates the screw conveyor means in a direction to push the organic matter from the supply port to the discharge port. and means for continuously receiving methane gas from the apparatus, said screw conveyor means having a length and diameter to substantially fill the cylindrical tank to convey the organic matter at a uniform rate over the length of the tank. and the screw conveyor means includes a tubular shaft supported by bearings provided at a first end and a second end of the tank, via the bearings and the tubular shaft, the anaerobic material is An apparatus for anaerobic digestion of organic matter, characterized in that it supplies a fluid that facilitates the digestion of organic matter and protects bearings from ingress of organic matter. 2. The screw conveyor means is supported by a support having one or more bearings between bearings at both ends of the tank, which bearings are also supplied with the fluid. Anaerobic digester for organic matter. 3. The apparatus for anaerobic digestion of organic matter according to claim 1 or 2, wherein the bearing at the first end is a thrust bearing. 4. The support having the bearing has legs extending radially from the bearing, the ends of the legs are fixed to the inner wall of the cylindrical tank, the bearing supports the screw shaft, and the support itself is divided into parts. 3. The apparatus for anaerobic digestion of organic matter according to claim 2, wherein the apparatus is disposed between screw blades. 5. The anaerobic digestion device for organic matter according to any one of claims 1 to 4, wherein the fluid is also supplied to a loop mesh provided on the inner wall of the cylindrical tank. 6. The anaerobic digestion device for organic matter according to claim 5, wherein the loop network is configured with a ring-shaped groove and a plurality of stringer holes. 7. Any one of claims 1 to 6, wherein the fluid is steam or pressurized water.
Anaerobic digestion equipment for organic matter as described in Section. 8. The outlet defined in the second end comprises an outlet for continuously discharging effluent at the upper end and a solid debris outlet at the lower end. The apparatus for anaerobic digestion of organic matter according to item 1. 9. The means for continuously receiving methane gas from the device includes a plurality of holes along the top of the cylindrical tank, a manifold covering the plurality of holes, and a means connected to the manifold to transport the methane gas from the device. An anaerobic digestion device for organic matter according to claim 1, characterized in that it is comprised of a duct. 10. The organic matter anaerobic device according to claim 1, wherein the motor drive means is provided outside the first end and comprises a worm gear attached to the screw shaft and a worm gear attached to the motor rotating shaft. Digestion device. 11 The cylindrical tank has a base forming at least one semi-cylindrical trough, at least one cover having a semi-cylindrical part shaped to be fixed to the base and forming a tube, and each end of the tube. 2. The apparatus for anaerobic digestion of organic matter according to claim 1, further comprising a plurality of end members for closing the section. 12. The organic matter anaerobic treatment according to claim 11, wherein the base has a plurality of semi-cylindrical troughs arranged in parallel at parallel intervals and a plurality of covers covering each semi-cylindrical trough. Digestion equipment. 13. The anaerobic digester for organic matter according to claim 12, wherein at least one part of the plurality of end members is a "U"-shaped tube connecting a plurality of semi-cylindrical troughs, respectively. . 14. The apparatus for anaerobic digestion of organic matter according to claim 13, characterized in that the connections are made in series. 15. The anaerobic digestion device for organic matter according to claim 13, characterized in that at least some of the connections are made in parallel. 16. The anaerobic digestion device for organic matter according to any one of claims 11 to 15, wherein the base is made of cast concrete. 17. An apparatus for anaerobic digestion of organic matter according to claim 1, characterized in that the feed tank is provided with means for discharging steam or hot pressurized water upward from the bottom in order to maintain the organic matter in a fluid state. 18. The anaerobic digestion device for organic matter according to claim 1 or 17, wherein the supply tank is equipped with heating coil piping at the bottom thereof. 19. Claim No. 1, characterized in that the substantially horizontal screw conveyor extending from the bottom of the supply tank to the organic matter supply opening at the top adjacent to the first end of the cylindrical tank is constructed in a closed tubular manner. The anaerobic digestion device for organic matter according to any one of items 1 to 18.