AU2006202894A1

AU2006202894A1 - Apparatus for Making Gas and Fertilizer From Food and Organic Wastes

Info

Publication number: AU2006202894A1
Application number: AU2006202894A
Authority: AU
Inventors: Byung-Dae Kang; Myung-Sun Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-07-06
Filing date: 2006-07-06
Publication date: 2008-01-24

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicants: Actual Inventors: Address for Service: Invention Title: Byung-Dae Kang Myung-Sun Lee Byung-Dae Kang Myung-Sun Lee HODGKINSON McINNES PAPPAS Patent Trade Mark Attorneys Level 3, 20 Alfred Street MILSONS POINT NSW 2061 "Apparatus for Making Gas and Fertilizer From Food and Organic Wastes" The following statement is a full description of this invention, including the best method of performing it known to us: P20552AU00 SAPPARATUS FOR MAKING GAS AND FERTILIZER FROM FOOD AND ORGANIC WASTES

NO

BACKGROUND OF THE INVENTION O" 00 Field of the Invention O The present invention relates to an apparatus for making c- gas and fertilizer from food and organic wastes using an anaerobic digester, and more particularly, to a food and O organic wastes treatment apparatus comprising: an anaerobic digester, which serves as a reactor carrying out a biochemical reaction, anaerobic digestion process, for decomposing organic matter, i.e. food and organic wastes, by use of specialized yeast, fungi and other bacteria; a gas collecting device for collecting gas generated by the anaerobic digestion process; devices for introducing and discharging the food and organic wastes into and from the anaerobic digester; a fermentation promoting device; a foam removal device for removing foam generated in the course of fermentation; and a solid matter removal device for removing solid matter as contaminants.

Description of the Related Art A kind of reactor for decomposing organic matter may be called a "digester".

More particularly, when the digester is used to carry out a reaction having no supply of oxygen from an external source, the digester may be called an "anaerobic digester".

Such a digester is one of the most important constituent Ch 5 devices of an anaerobic digestion facility, and carries out 00 decomposition of organic matter therein. The digester may be ND connected to a gas generation facility for utilizing methane gas generated in the course of decomposition of organic matter. Examples of the organic matter to be treated in the 0 digester include food and organic wastes, fishery waste, vegetable waste, tree leaves, and so on. In addition to the methane gas, the decomposition of organic matter, i.e.

digestion of organic matter, includes liquid-phase fertilizer as byproduct. The fertilizer may remaining be recycled as compost via a proper extraction process after passing through a proper extraction process.

Problems of conventional anaerobic digesters are in that organic matter must be subjected to several treatments including a secondary fermentation treatment, and a cleaning process for removing foam generated in the digester causes deterioration of treatment efficiency. Further, in the case of conventional anaerobic digesters, it is difficult to maintain a proper interior temperature of the digester required for the decomposition of organic matter.

Considering a representative example of conventional anaerobic digesters carrying out bio-chemical reactions, it takes the form of a cylindrical upright tank including a IND primary acid basin and a secondary anaerobic basin. The tank

C)

is generally formed of cement concrete, and contains a mixing 5 device therein. The conventional anaerobic digester has 00 several problems as follows. Firstly, since the anaerobic IND basin performs a mixing operation once per day, the organic C-i matter, having passed through the mixing operation, may be in an incompletely treated state, and thus, there is a necessity .0 for a post-fermentation course. Secondly, due to sand, soil and other unpurified solid matter accumulated in the primary and secondary basins during operation, the entire treatment capacity of the basins may be deteriorated after the lapse of a long time period. Thirdly, the conventional anaerobic digester suffers from not only excessive foam generated during operation, but also an increased amount of organic matter clump gathered in inner upper regions of the primary and secondary basins. Fourthly, an operating temperature of the anaerobic basin has to be changed frequently to fulfill variable operational conditions of the anaerobic basin, and therefore, the conventional anaerobic digester has uneconomical operation due to delay in work and relatively long operation time.

SUMMARY OF THE INVENTION Z Therefore, the present invention has been made in view D of the above problems, and it is a first object of the present invention to provide an anaerobic digester, which has the C\ 5 following advantages: firstly, the anaerobic digester takes 00 the form of a horizontal single reactor unifying conventional ND primary and secondary reactors, thus achieving reduced installation costs; secondly, high operational efficiency can be achieved as a result of considerably increasing an .0 anaerobic fermentation process for digesting organic matter at a temperature of 55 to 70 degrees centigrade while reducing an acid reaction; thirdly, there is a necessity for a secondary fermentation process because organic matter is sufficiently fermented in the anaerobic digester for 20 to 30 days; and fourthly, maximized operational efficiency can be continuously maintain because a full amount of the organic matter, i.e.

food and organic wastes, can be treated in a completely sealed state of the anaerobic digester.

It is a second object of the present invention to achieve easy discharge of solid matter during continuous operation of an anaerobic digester by collecting the solid matter, such as sand, soil, bone scraps, etc. sunk to the bottom of the digester, in a solid matter collecting container, which is provided in the bottom of the digester at a location near an exit end of the anaerobic digester, by use of spiral rotating operation of mixing agitator plates and paddles connected to a horizontal shaft mounted in the ND digester, and discharging the collected solid matter to the outside of the digester by means of a screw conveyor.

Ch 5 It is a third object of the present invention to remove 00 foam, which is gathered in a gas collecting channel of an IND anaerobic digester, by injecting water (which is treated liquid phase organic matter residue existing in a region near an exit end of the digester) by means of an injector and pump .0 and via circulation of water inside the anaerobic digester, thereby preventing a gas hose connected to a gas generator from being clogged with the foam and thus, preventing deterioration in the operational efficiency of the anaerobic digester.

It is a fourth object of the present invention to efficiently regulate the interior temperature of an anaerobic digester by providing a pair of vertical plates in the interior of the digester and three or more heat exchangers at the outer surface of the digester, both the vertical plates and heat exchangers being connected to a manifold of a temperature regulating device, thereby keeping the interior of the digester at a temperature suitable for the fermentation of bacteria, and achieving reduction in operation costs of the anaerobic digester.

It is a fifth object of the present invention to prevent generation of odor from an anaerobic digester and other Zstorage tanks of a food and organic wastes treatment apparatus IN by sealing the digester and tanks with a sealing cap, cover, etc. after food and organic wastes are introduced into the C" 5 treatment apparatus, and delivering gas into a generator 00 Cq through a hose so as to burn in the generator.

(NO

BRIEF DESCRIPTION OF THE DRAWINGS 0 The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic systematical diagram illustrating an apparatus for making gas and fertilizer from food and organic wastes according to an exemplary embodiment of the present invention; FIG. 2 is an entire sectional view illustrating a horizontal anaerobic digester according to the present invention; FIG. 3 is a sectional view illustrating a structure for removing foam from the digester according to the present invention; FIG. 4 is a sectional view illustrating a screw conveyor for extracting solid matter accumulated on the bottom of the Qdigester according to the'present invention; and FIG. 5 is a diagram illustrating a temperature INO regulating device for regulating the interior temperature of the anaerobic digester according to the present invention.

(s 00oo DESCRIPTION OF THE PREFERRED EMBODIMENTS

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Now, an apparatus for making gas and fertilizer from food and organic wastes using an anaerobic digester according to the LO present invention will be explained in detail with reference to the accompanying drawings.

Referring to FIG. 1 depicting a schematic systematical diagram, food and organic wastes are first crushed in a crusher 1 into small particles, and then, the small particles are delivered into a storage tank 2.

A plurality of heat exchangers 64 are separately mounted to an anaerobic digester 4 and adapted to perform a heat exchange operation under operation of a manifold 66 of a temperature regulating device 65. Thereby, the anaerobic digester 4 is able to be kept at a temperature between 55 to degrees centigrade.

Once organic matter is introduced into the anaerobic digester 4, the organic matter is digested for 20 to 30 days via an anaerobic fermentation process using yeast, bacteria, fungi, and so on. In the course of the anaerobic fermentation, gas is generated from the organic matter. The digested organic matter and gas are delivered into an organic ND fertilizer storage tank 8, and then, delivered again into a moisture separator 9. While passing through the moisture Ch 5 separator 9, liquid organic fertilizer is separated from 00 p methane gas. The methane gas then burns in a generator 63 for ND the removal of odor.

A Referring to FIG. 2 illustrating the anaerobic digester in sectional view, the anaerobic digester 4 takes the form of .0 a horizontal cylindrical tank. The anaerobic digester 4 is formed of an iron plate, and is externally surrounded by a heat insulating material. Opposite ends of the anaerobic digester 4 are closed by a pair of outwardly convex curved plates 26, respectively. The anaerobic digester 4 is placed on base blocks 11, which are partially buried in the ground, by interposing rubber plates 13 located on the respective base blocks 11. The anaerobic digester 4 has a food and organic wastes introduction pipe 14 penetrated at a location near an entrance end of the digester 4 for the introduction of organic matter to be digested by anaerobic bacteria.

The anaerobic digester 4 further has a discharge pipe 16 penetrated at a location near an exit end of the digester 4 for the discharge of the digested organic matter. As shown in FIG. 2, a plurality of vertically extending homogenizers, which constitute a mixing device, are equidistantly arranged in a longitudinal direction of the anaerobic digester 4.

Specifically, the mixing device includes a horizontal shaft ND 23, a plurality of mixing agitator plates 20 equidistantly arranged along the shaft 23 and paddles 21 attached to C\ 5 opposite ends of each mixing agitator plate 20. As the shaft 00 23 rotates at a low speed, the organic matter is pushed little IND by little in the anaerobic digester 4.

The paddles 21 of the mixing agitator plates 20 have a spiral shape, and are adapted to push the organic matter in .0 the direction as designated by the arrow T of FIG. 2. Two vertical plates 60 are mounted in the anaerobic digester 4 at positions near the entrance end of the digester 4. The vertical plates 60 have a height corresponding to approximately two thirds of the inner diameter of the anaerobic digester 4, and provide a shock-absorbing zone for preparing the anaerobic digestion of the introduced organic matter. The vertical plates 60 are also connected to the manifold 66 of the temperature regulating device 65, so as to perform the role of a heat exchanger. Accordingly, the vertical plates 60 have important roles of not only regulating the temperature of the introduced organic matter, but also preventing the organic matter from clumping.

Since the vertical plates 60 have a height corresponding to approximately two thirds of the inner diameter of the anaerobic digester 4, the organic matter, introduced into the digester 4, is guided inward through a space 62, which is defined over the vertical plates 60 and has a height D corresponding to approximately one third of the inner diameter of the anaerobic digester 4. In operation, the introduced C 5 organic matter is mixed by use of its introduction pressure 00

(N

and spiral rotation of the above mentioned mixing device ND provided in the digester 4 while being pushed in the direction Cl of the arrow T.

The two vertical plates 60, which are located near the .0 entrance end of the anaerobic digester 4, are spaced apart from each other in such a manner that two mixing agitator plates 20, each having two paddles 21 at opposite ends thereof, are located adjacent to the two vertical plates respectively, while being coupled on the shaft 23, to obtain a set of the vertical plate and mixing device. The paddles 21 of each mixing agitator plate 20 extend horizontally such that they are coupled perpendicularly to the vertical mixing agitator plate 20, and also, are adapted to rotate spirally.

With this configuration, the introduced organic matter is overlapped in a region U of an interior chamber 12 of the anaerobic digester 4, thus achieving high-efficiency homogenizing motion thereof.

The organic matter is maintained in the interior chamber 12 of the anaerobic digester 4 for 20 to 30 days.

Simultaneously, a predetermined amount of organic matter is c- automatically introduced several times a day, and repeatedly mixed and agitated by operation of the mixing device in the ND anaerobic digester 4. Preferably, the predetermined amount of organic matter is approximately one twentieth to one thirtieth 5 of the volume of the anaerobic digester 4.

00 As shown in FIG. 2, a gas collecting channel 22 is IND formed at a location near an exit side of the interior chamber C- 12 of the anaerobic digester 4, and in turn, a gas hose 18 is connected to the gas collecting channel 22.

.0 The interior chamber 12 of the anaerobic digester 4 is preferably configured such that the height thereof gradually increases in the direction of the arrow T. This allows methane gas, carbon dioxide gas, and so on, which are generated when the organic matter is digested, to be easily collected in the gas collecting channel 22, and consequently, to be delivered into the gas generator 63 through the gas hose 18.

Referring to FIG. 3 illustrated as sectional view, a foam detecting device 32 having a foam sensor 33 and a foam removal device 40 having an injector 42 are mounted in the gas collecting channel 22. Both the foam detecting device 32 and foam removal device 40 are connected to a control device 36 by use of a connection line 38 and pump hose 44, respectively.

The pump hose 44 is provided at a certain location thereof with a pump 46. If foam 34 is generated in an internal space of the gas collecting channel 32, the foam sensor 33 sends a signal to the foam detecting device 32. As the signal is D transmitted to the control device 36, the control device 36 outputs a command signal for initiating operation of the pump C\ 5 46. Thereby, the foam, which is generated in the anaerobic

OO

digester 4 and delivered into the internal space 30, can be ND removed by operation of the foam removal device 40. The c- removal of foam provides several advantages. That is, it is possible to prevent the foam from hindering the supply of gas 0 into the generator 63, and to eliminate any operational errors of the anaerobic digester 4 due to foam. This also is efficient to reduce operator's careless manipulation.

Moreover, the present invention has an advantage in that foam can be removed by use of water inside the anaerobic digester 4 without exerting bad effect on normal operation of the anaerobic digester 4.

FIG. 4 illustrates a screw conveyor 52 in sectional view. The screw conveyor 52 is used to remove solid matter having a high specific gravity, such as sand, soil, bone scraps, etc. introduced in the anaerobic digester 4. Through the use of the screw conveyor 52, the solid matter can be discharged without stopping operation of the anaerobic digester 4, and therefore, high operational efficiency of the anaerobic digester 4 can be continuously maintained. A solid matter collecting container 50 is provided in the bottom of the anaerobic digester 4 at a location near the last paddle 21. The solid matter collecting container 50 serves to ND temporarily store the solid matter falling from the interior chamber 12, to allow the solid matter to be delivered using 5 the screw conveyor 52. To collect the delivered solid matter, 00 a solid collecting tank 54 is provided at the outside of the ND anaerobic digester 4.

Specifically, as a result of continuous rotation of the shaft 23, mixing agitator plates 20 and paddles 21, the solid .0 matter, which is introduced into the anaerobic digester 4 through the introduction pipe 14, sink to the bottom of the interior chamber 12, and is delivered in the direction of the arrow T, thereby allowing the solid matter to be put into the solid matter collecting container The organic matter except for the solid matter is returned into the interior chamber 12 via a conveyor belt, thus allowing only the solid matter as contaminants to be delivered out of the anaerobic digester 4 by means of the screw conveyor 52, so as to be collected in the collecting tank 54 provided at the outside of the anaerobic digester 4.

FIG. 5 is a diagram illustrating the temperature regulating device 65 for regulating the interior temperature of the anaerobic digester 4. To obtain efficient operation of the anaerobic digester 4, it may be often necessary to change the interior temperature of the digester 4. For this reason, the temperature regulating device 65 is mounted in the digester 4. The temperature regulating device 65 includes the D plurality of heat exchangers 64 mounted on an outer lower surface of the digester 4 at a location near the introduction ,h 5 pipe 14.

00 The vertical plates 60 disposed in the digester 4 are ND connected to the manifold 66 of the temperature regulating ci device 65 to perform the role of a heat exchanger. Therefore, the interior temperature of the digester 4 can be more .0 efficiently regulated by both the vertical plates 60 as well as the heat exchangers 64. In this case, delicate regulation management of the temperature is performed by the manifold 66 connected to a side surface of the anaerobic digester 4 at a location near the introduction pipe 14.

In consideration of the fact that the anaerobic digester 4 of the food and organic wastes treatment apparatus may be installed in a densely inhabited district, the present invention has an advantage in that all facilities for the removal of odor are sealed efficiently.

To prevent odor, which is emitted from the organic matter introduced into the storage tank 2 after passing through the crusher 1, from being discharged out of the anaerobic digester 4, the horizontal anaerobic digester installed on the ground is provided with a sealing cap, heat insulation cover and other covering members. The odor inside the anaerobic digester 4 is delivered to the gas generator 63 through the gas hose 18. As a result, the generation of odor can be minimized through a later D gas burning process, and the present invention provides a safe facility suitable for the protection of environment.

O\ 5 With the anaerobic digester 4 having the above described 00 configuration, the organic matter, which is introduced into the IND digester 4 through the introduction pipe 14, is able to be C-i homogenized while being pushed toward the discharge pipe 16 by operation of the mixing agitator plates 20 and spiral pads 21 0 connected to the shaft 23. Also, since the interior chamber 12 of the anaerobic digester 4 can be kept at a temperature of to 70 degrees centigrade through the temperature regulation using the manifold 66 of the temperature regulating device digestion efficiency of anaerobic bacteria, yeast, fungi and so on can be improved, and thus, the production rate of methane gas increases. The produced gas is collected in the internal space 30 of the gas collecting channel 32 in a simplified manner, and then, is delivered into the generator 63 through the gas hose 18 to burn in the generator 63. This results in improvement in the removal of odor as well as the production of gas. Furthermore, the anaerobic digester 4 of the present invention has a sufficient organic matter digestion period for to 30 days, and thus, has no necessity for a secondary fermentation process. Therefore, the anaerobic digester 4 can produce gas and liquid fertilizer with high efficiency.

As apparent from the above description, the anaerobic digester 4 is fabricated as a horizontally extending single IND device, and allows the organic matter, which is introduced C) into the anaerobic digester 4 through the introduction pipe 14 5 at regular intervals, to be delivered in the direction of the 00 arrow T. When the solid matter is introduced into the IND anaerobic digester 4 along with the organic matter, the solid c- matter can be collected in the solid matter collecting container 50 so as to be discharged to the outside of the .0 digester 4 by means of the screw conveyor 52. The use of the screw conveyor 52, accordingly, results in ease in the separation and removal of the solid matter. Further, the interior temperature of the anaerobic digester 4 can be regulated by use of the manifold 66 of the temperature regulating device 65 and the heat exchangers 64 mounted at the outer lower surface of the anaerobic digester 4, so as to be kept at a temperature of 55 to 70 degrees centigrade suitable for the digestion of yeast, fungi, bacteria, etc.

Furthermore, the anaerobic digester 4 is surrounded by a heat insulating cover for the heat insulation of the heat exchangers 64. This has the effect of increasing the thermal efficiency of the anaerobic digester 4, and consequently, improving digestion efficiency. Also, even if foam is gathered in the internal space 30 of the gas collecting channel 32, the foam can be easily removed by injecting water inside the anaerobic digester 4 by use of the injector 42.

This enables the gas to be efficiently delivered into the IND generator 63 without the risk of clogging of the gas hose 18, resulting in economical operation and highly efficient 5 production of gas and liquid fertilizer.

00 Although the preferred embodiment of the present IND invention has been disclosed for illustrative purposes, those c- skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing 0 from the scope and spirit of the invention as disclosed in the accompanying claims.

The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of "having" or "including" and not in the exclusive sense of "consisting only of".

Claims

1. An apparatus for making gas and fertilizer from food and organic wastes comprising: C* 5 a crusher for crushing the food and organic wastes into 00 small particles; INO a storage tank for storing the crushed small food and Ci organic wastes particles from the crusher; an anaerobic digester for digesting and decomposing the .0 small particles using yeast, fungi and bacteria, the digester containing a rotating shaft extending along a longitudinal center axis thereof and mixing agitator plates and paddles connected to the shaft; an organic fertilizer storage tank for storing liquid fertilizer; a moisture separator for separating liquid fertilizer; and a generator for burning methane gas.

2. The apparatus according to claim 1, wherein the anaerobic digester is horizontally placed on base blocks by interposing rubber plates such that a gas collecting channel thereof is located higher than the remaining part for easy collection of gas, and a gas hose is connected to an upper end of the gas collecting channel to supply gas into the Zgenerator. n

3. The apparatus according to claim 1, wherein: the Ch 5 anaerobic digester has a food and organic wastes introduction 00 p pipe penetrated at a location near an entrance end thereof and ND a discharge pipe penetrated at a location near an exit end cq thereof; and the mixing agitator plates and paddles are equidistantly 0 attached to the center rotating shaft in the digester and adapted to mix the organic matter via spiral rotation thereof while gradually delivering the organic matter to the discharge pipe at constant intervals.

4. The apparatus according to claim 1, wherein the anaerobic digester contains two vertical plates for preventing organic matter introduced into the digester from being clumped.

5. The apparatus according to claim 1, further comprising: a foam detecting device having a foam sensor, which is mounted in a gas collecting channel of the anaerobic digester and connected to a control device via a connection line; and an injector mounted in the gas collecting channel and connected to a pump via a pump hose for removing foam gathered in the gas collecting channel by use of water inside the anaerobic digester. 5

6. The apparatus according to claim i, wherein a solid 00 (N matter collecting container is provided in the bottom of the IND anaerobic digester such that solid matter is collected in the (Ni container to be discharged to the outside of the digester by means of a screw conveyor. .0

7. The apparatus according to claim 1, wherein a plurality of heat exchangers are mounted to an outer lower surface of the digester and connected to a manifold of a temperature regulating device, so as to keep an interior temperature of the digester in the range of 55 to 70 degrees centigrade.

8. The apparatus according to claim 4, wherein the vertical plates inside the digester are connected to a manifold of a temperature regulating device to perform the role of a heat exchanger.

9. The apparatus according to claim 1, wherein the crusher, storage tank, anaerobic digester, organic fertilizer storage tank and moisture separator are sealed, and the gas Sgenerated in the sealed devices is delivered into a generator Sthrough a gas hose to burn in the generator for the removal of \O odor. An apparatus for making gas and fertilizer from food (N Sand organic wastes as substantially hereinbefore described and N with reference to the Figures. Dated this 6 th day of July 2006. Byung-Dae Kang Myung-Sun Lee By: HODGKINSON McINNES PAPPAS Patent Attorneys for the Applicant