WO2007068446A1

WO2007068446A1 - Plant and process for generating biogas from biodegradable material containing liquid and solid components, in particular waste products, and also biogas generation container for use in the plant

Info

Publication number: WO2007068446A1
Application number: PCT/EP2006/011948
Authority: WO
Inventors: Dietrich Eichler; Friedrich Weigand; Matthias Rabener
Original assignee: Röhren- und Pumpenwerk Bauer Gesellschaft m.b.H.
Priority date: 2005-12-14
Filing date: 2006-12-12
Publication date: 2007-06-21
Also published as: RU2383497C1; RU2008128492A; EP1966095A1; CA2628323A1

Abstract

A plant for generating biogas from organic biodegradable material containing liquid and solid components, such as waste products, in particular liquid manure from agricultural enterprises, comprises a biogas generation container (9) having a feed for the degradable material and a biogas collection zone (6) having a biogas outlet, and a flotation separation unit having a microbubble generation unit (15) for separating off the solid components from the liquid components of the degradable material. The flotation separation unit comprises a chamber region (14) which is delimited in the interior of the biogas generation container and essentially active in the direction of gravity and having a closed bottom and an open upper end arranged below the liquid level of the biogas generation container. Clarified liquid from the chamber region and a gas, in particular the biogas from the biogas collection region, can be fed to the microbubble generation unit for charging the liquid with gas. The outlet of the microbubble generation unit is connected to an inlet (18) of the chamber region in order to recycle microbubble-forming clarified liquid to the chamber region. Near the bottom of the chamber region, an outlet (116) for clarified liquid from the chamber region is provided. The flotation separation takes place in the chamber region in countercurrent flow to the ascending microbubbles.

Description

Plant and method for producing biogas from biodegradable material containing liquid and solid components, in particular waste products, and biogas production containers for use in the plant

The invention relates to a plant and a process for the production of biogas from liquid and solid components containing organic, biodegradable material, in particular waste products, such as manure from farms, and a biogas production container for use in the system.

The invention relates in particular to the concentration of anaerobic biomass in fermenters for the production of biogas.

A known plant (US Pat. No. 5,015,384 A) comprises a biogas production container from whose upper region the biogas obtained can be taken off, and a flotation separation device provided outside the container. In this liquid from the container derived biomass can be introduced together with a gas for microbubble formation to separate solids from the biomass. These are reintroduced into the container, while purified liquid can be diverted for further use. The flotation separation thus takes place outside the biogas production tank in a separate flotation separator.

The invention has for its object to provide a compact formable biogas plant and a related method with increased efficiency in terms of the temporal yield of biogas, so that lower operating and investment costs are possible. To solve this problem, reference is made to the claims 1 and 8.

A feature of the invention is the flotation separation into liquid and solid components within the biogas production container by means of a chamber region defined therein. In the chamber area clarified liquid is obtained, which can be deducted from the lower part of the chamber area. At the same time, there is a continuous exchange of separated solid biomass from the chamber area for mixing with the waste products in the container and waste products in the chamber area, without the need for separate feed and discharge systems. It is thereby obtained a continuous concentration of anaerobic biomass for the production of biogas, whereby the effectiveness of the system is substantially increased. According to one embodiment of the invention, the generation of microbubbles in the chamber region can be effected by feeding a branched-off partial stream of the clarified liquid from the chamber region to a device for gassing and returning the fumigated liquid to the chamber region where the gas is released due to expansion effects in the form of Microbubbles is released. According to another embodiment, a gas can be introduced into a porous substrate in the chamber region, which bubbles out of the substrate in the form of microbubbles. As fine microbubbles as possible should be generated in order to detect a large proportion of the solid biomass by the effect of surface tension and to raise it in the chamber area. The delimited chamber area ends at a sufficient distance below the level of the liquid in the biogas tank. Thus, the waste products supplied to the chamber area flow from above through the delimited area in countercurrent to the ascending microbubbles.

The biodegradable material is preferably subjected to additional mechanical separation into liquid and solid components, preferably by means of a press screw separator, before or after introduction into the biogas production container. It can according to an embodiment of the invention, from the mechanical separation of liquid components obtained are divided into different subsets and returned to the chamber area. It is characterized in the chamber area a certain advantageous division of the bottom and the open end of the chamber area directed toward Fliissigkeitsströme obtained with a different flow rate in countercurrent to the ascending microbubbles, whereby the effectiveness of the system can be further increased. According to another aspect of the invention, there is provided a biogas generation container.

The invention will be explained in more detail with reference to embodiments and the drawing. Show it:

1 is a schematic, partially sectioned view of a biogas plant according to a first embodiment of the invention, incorporated in a plant for the separation of manure from farms into liquid and solid components,

2 in a view and environment similar to FIG. 1, a biogas plant according to a second embodiment of the invention,

3 shows an enlarged, fragmentary view of a delimited region of a biogas container of the biogas plant according to FIG. 2, FIG.

4 shows the demarcated region of the biogas container according to FIG. 3 in a cross-sectional top view, FIG.

5 shows a view similar to FIG. 1 of a biogas plant according to a third embodiment of the invention,

Fig. 6 in a view similar to Fig. 4 the demarcated region of the biogas container of FIG. 5 in a cross-sectional plan view, and 7 shows the demarcated region of the biogas container according to FIG. 5 in a cross-sectional top view.

Although the invention will be described below in connection with biogas production from manure produced on farms and shown in the drawing, it should be understood that no limitation of the protection of the invention is to be taken in this application. Rather, it can also be used advantageously for the biogas production from materials and waste from other sources, in particular municipal or industrial enterprises.

As shown in Fig. 1, in the first embodiment of the invention, the liquid manure obtained in a stable plant 1, which may contain liquid and solid components, is introduced via a pipe 2 into a collecting tank 3; it can be homogenized therein by means of a stirrer 4. A pump 5 is provided to supply the homogenized slurry from the sump 3 to a solids / liquid separator 6. The solid / liquid separator 6 is preferably a screw extruder such as e.g. in EU-B-0367037, so that reference may be made thereto for further details. Other types of solid / liquid separators may also be used if desired.

The separated in the solid / liquid separator 6 solid phase is, as indicated at 7, heaped and can, if necessary in composted form, discharged as a fertilizer on fields or used after a suitable aerobic treatment as litter in barns.

The solid phase largely freed liquid phase of the slurry is via a line 8 in a biogas production tank or biogas digester 9 a initiated biogas plant constructed according to the invention. An agitator 10 in the container 9 is provided to constantly mix the liquid therein, which is indicated by dotted lines in the drawing.

Instead of or in addition to an agitator 10 may also be a pump circulation (not shown) by means of a liquid sucking from the container and provided therein tangentially recirculating pump.

The formation of the biogas is carried out by fermentation of the biomass in the presence of anaerobic bacteria, as is generally known in the art, so that a more detailed explanation of this process is unnecessary.

Although not shown in the drawing, further deposition of solid matter still present in the liquid output of the solid / liquid separator 6 in the form of e.g. fine sand-like ingredients are provided. Preferably, this deposition can take place by means of a centrifugal separator integrated in the line 8. The additional separation ensures that the biogas production tanks 9 do not form any sludge deposits of fine particles that are not biodegradable.

The formed biogas collects, as indicated by dotted lines in the drawing, in the upper, covered by a foil or the like area 11 of the container 9, which serves as a biogas storage. From there, the biogas can be discharged via a line 12 for further use, for example for power generation by means of a micro gas turbine.

According to the invention, a dividing wall 13 projecting upwards from the bottom thereof is provided in the interior of the container 9, which creates an upwardly open demarcated area 14 in the container 9, cf. also FIG. 4. The dividing wall 13 terminates at a suitable distance of, for example, approximately zero , 5 to 1, 0 m, below the liquid peak gels in the container 9, which is indicated in the drawing by a dashed line.

In the demarcated area 14 finds a further separation of liquid and. still existing solid biomass according to the flotation separation principle instead. For this purpose, purified liquid is discharged to the outside via a line 16 near the bottom of the delimited area 14, which liquid is supplied to a device 15 for microbubble formation. Such micro bubble devices are known to the person skilled in the art. They serve to provide suitable for a Flotatonsabscheidung microbubbles with the means of an initial entry of gas into a liquid under pressure increase and subsequent flow-intensive relaxation of the liquid in a cavitation field. As a gas, in the system according to the invention, part of the biogas is branched off from the line 12 and introduced via the line 17 into the micro bubble device 15. In particular, can be sucked by throttling the liquid flow in front of a centrifugal pump (not shown) biogas and brought under pressure in the purified liquid to the solution. By a flow-intensive relaxation dissolved gas fractions are torn out of the liquid again in the cavitation field. This micro-bubbles form in the micron range. One type of microbubble device is e.g. in DE 3733583 A described.

The gasified clarified liquid is returned via line 18 to the demarcated area 14 near the bottom thereof. The bubbling from the liquid gas bubbles rise in the demarcated area 14 upwards, while at the same time the introduced into the container 9 via the line 8 liquid biomass flows from above into the demarcated area 14 in Gegeπstrom to the ascending microbubbles. When floating, the microbubbles rupture particles in the liquid biomass with it, leaving behind the bottom of the delimited area 14 cleared and largely odor-relieved liquid. Due to the surface tensions, even very fine biomass particles combine with the microbubbles and are carried upwards with them. The clarified liquid can be discharged to the outside via a line 20 branching off from the line 16. A vent 21 may be provided to ensure a continuous suction-free operation in the conduit 20. With 19 defined by the line 20 overflow height is indicated, which determines the maximum level of liquid biomass in the container 9.

The stirrer 10 keeps the liquid biomass in the entire container 9 in motion and at the same time leads away from the demarcated area 14, the rising due to the flotation solid biomass and mixes them with the remaining contents of the container. 9

To support the mixing of the separated solid biomass with the remaining contents of the container 9, the suction side of the agitator 10 may be provided with a guide tube (not shown), which may be formed by a possibly forming biomass floating layer near the delimited area 14 to behind the agitator 10 can be performed.

In Fig. 2 to 4, the second embodiment of the invention is shown.

In this embodiment, as in the first embodiment described above, from a stable plant (not shown) of liquid and solid components, slurry 100 is introduced into a sump 102 at a certain flow rate; it can be homogenized therein by means of a stirrer 103. A pump 104 conveys the liquid from the collecting container 102 to a biogas container 105. The biogas 106 formed therein collects under a storage foil 107, which can be reinforced by, for example, a PVC-coated polyester fabric 108. The biogas can be discharged from there for further use. A pair of agitators 109 at diametrically opposite locations of the biogas container 105 may be provided to constantly mix the contents of the container.

Inside the container 105, as in the first embodiment of the invention, a partition wall 113 projecting upwardly from the container bottom is provided, which creates an upwardly open demarcated region 114 in the container 105, cf. also Fig. 4. The partition 113 terminates at a suitable distance from e.g. about 0.5 to 1, 0 m below the liquid level in the container 105, which is indicated in the drawing by a dashed line.

Via a suction line 110, manure can be withdrawn from the bottom of the biogas tank 105 at a location outside the delimited area 114 by means of a pump 111 and fed to a solids / liquid separator 112. The solid / liquid separator 112 is preferably a screw extruder similar to the first embodiment.

The amount of manure withdrawn from the biogas tank 105 is, according to the invention, approximately 10 to 20% greater than the throughput through the plant.

In the separator 112, the solid components are separated from the manure. The deposited solid, as indicated at 130, may be used further for e.g. heaped up for removal by means of a trailer.

A larger subset of the total amount of liquid draining from the separator 112 is supplied to the separated region 114 of the biogas container 105 at a suitable location near the upper open end, preferably within its upper third, via a conduit 122. As in the above-described first embodiment of the invention, a centrifugal separator or other suitable deposition device for separating fine, For example, sandy components that are not biodegradable can be provided in the liquid.

A small portion of the amount of liquid draining from the separator 112 is supplied to a microbubble forming means 115 and exits the microbubbled liquid via a conduit 123 into the separated area 114 at a suitable location near its bottom, preferably within the lower third is initiated.

The micro bubble device 115 may have a similar construction as in the first embodiment of the invention. As the gas, in turn, preferably a part of the biogas formed is used, as indicated in Fig. 2 by the dashed branch line 127 '.

Via a drain line 121 provided near the bottom of the separated region 114, the liquid reduced by the solids content can be removed from the demarcated region 114 of the biogas plant and collected in an intermediate storage 117 for further use. For example, the liquid accumulated in the intermediate storage 117 can be made available as a liquid fertilizer via a drain 118 of agriculture.

The biogas produced can be used for further use, e.g. Electricity or heat generation via a line 127 to a cogeneration unit 119 are supplied. The resulting heat can be used to promote the biodegradation heating of the contents of the biogas container 105 by means of a heat exchange device provided therein, as indicated at 120.

With reference to FIG. 3, the flow characteristics resulting from the aforementioned liquid supply in the delimited region 114 are explained below. Via the line 122, the smaller amount of partial flow enters the delimited area 114, while the main amount of flow is introduced via the line 123, so that the total sum of both subsets in the demarcated area 114 enters. Via the line 121 arranged close to the bottom of the separated region 114, a certain quantity of liquid reduced by the solids is drawn off. In this case, the originating from the line 122 liquid splits into a partial flow 124 with a lower flow rate, which flows back into the biogas tank 105, while a partial flow 125 with a larger flow rate flows to the bottom of the demarcated area 114 and is discharged via the drain line 121 to the outside.

Due to their buoyancy, the microbubbles 126 from the gassed liquid quantity supplied via the line 123 move upwards against the partial stream 125 and unite by their surface tension with the solid biomass present in the partial stream 126, which thus returns together with the partial stream 124 back into the biogas container 105 reach.

4 shows the demarcated area 114 in plan view. As can be seen, the partition wall 113 extends arcuately from an attachment point on a side wall of the biogas container 105 to a circumferentially spaced connection point, so that the delimited area 114 can have a substantially kreisseg- mentförmigen cross-section. However, the invention is not limited to such a configuration of the demarcated area 114, which accordingly may be formed in any other suitable manner. Example 1 :

A total of 10 m ³ / h separated liquid accumulates on the solid / liquid separator 112. This is divided into a larger subset of 9 m ³ / h and a smaller subset of 1 m ³ / h. The larger subset is introduced via the line 122 in an upper third of the chamber portion 114, the smaller subset after gassing in the lower third via the line 123. Via line 121 8 m ³ / h clarified liquid are withdrawn from the chamber area. The time amount of the upward liquid flow 124 in the chamber area is 2 m ³ / h and that of the downward flow 125 is 7 m ³ / h. The downward current 125 and the subset 123 thus correspond in total to 8 rrvVh of the withdrawn current 121.

In Fig. 5 to 7, the third embodiment of the invention is shown. This differs from the second embodiment essentially in a modified type of microbubble formation in the delimited chamber area, so that reference can be made to the description of the second embodiment with regard to the remaining structural parts. The same or similar components therefore carry the same reference numerals, but changed by the first-digit number "2-".

Unlike in the previously described embodiments, microbubble formation does not take place by means of a microbubble device provided outside the biogas container, but its interior, with a microporous ceramic disk-shaped substrate 229 at a near-bottom region of the delimited chamber region 214, into the gas under pressure through a line 228 can be introduced, which ausperlt in the form of microbubbles from the microporous ceramic substrate 229. A suitable microporous ceramic substrate material may be obtained under the tradename "Kerafol" from Keramische Folien GmbH, Stegenthumbach 4-6, D-92676 Eschenbach, Germany. The gas is preferably, in turn, from the biogas container 205. shown biogas, which is offset by means of a built-in line 228 compressor 231 under a suitable pressure before it reaches the microporous ceramic substrate 229.

Example 2:

A total of 10 m ³ / h separated liquid accumulates on the solid / liquid separator 212. This is introduced via the line 222 in an upper third of the chamber portion 214. Via the line 221 8 nrVh clarified liquid are withdrawn from the chamber area. Biogas at a pressure of 2.2 bar is introduced via line 228 into the microporous ceramic substrate 229. The time amount of the upward liquid flow 224 in the chamber region is 2 nfVh and that of the downward flow 125 is 8 m ³ / h.

Although the gassing in the microbubble generating device using the recovered biogas has been advantageously described previously, it should be understood that, if desired, suitable foreign gasses may also be used by a foreign gas source.

Claims

claims

1. Plant for the production of biogas from organic and biodegradable material containing liquid and solid components, such as waste products, in particular manure from agricultural operations, comprising a biogas production container (9, 105, 205) having a feed for the biodegradable material and a biogas collecting area (6, 106, 206) with a biogas outlet, and a flotation separator having a microbubble generator (15, 115, 229) for separating the solid from the liquid constituents of the biodegradable material, the flotation separator comprising a chamber region (14, 14, 214, 149) defined in the interior of the biogas generation container and substantially in the direction of gravity ) comprising a closed bottom and an open upper end located below the liquid level of the biogas production container, and wherein the microbubble generator comprises a gas, in particular the biogas the Biogassammeibereich, can be supplied to form microbubbles in the chamber area.

2. Installation according to claim 1, characterized in that the Mikroblasenerzeu- generating device (15,115) outside the biogas production container (9,105) is arranged, wherein the microbubble generating means clarified liquid from the chamber region (14,114) and gas for supplying the clarified liquid are supplied with gas, while an outlet of the gas-treated clarified liquid micro-bubble generator is connected to an inlet (18, 123) of the chamber portion.

3. Plant according to claim 2, characterized in that the inlet (18,123) for the gas-treated clarified liquid near the bottom of the demarcated chamber area (14,114) is provided.

4. Installation according to claim 1, characterized in that the Mikroblasenerzeu- generating device (229) comprises a within the chamber region (214)) arranged microporous ceramic substrate material (229), is introduced into the pressurized gas.

5. Plant according to one of claims 1 to 4, characterized by an agitator means (10,109,209) in the interior of the biogas production container (9,105,205) for mixing the container contents.

6. Plant according to one of the preceding claims, characterized by a Biogaserzeugungsbehälter (9) upstream solid / liquid separation device (6) for the separation of solid components of the biodegradable Matzerials before their introduction into the biogas production container.

7. Plant according to claim 6, characterized in that the solids / liquid separation device (9) comprises a press cell separator.

8. Plant according to claim 5, characterized in that the agitator means (10,109,209) comprises a guide tube to suck a near the upper open end of the chamber area (14,114,214) formed Biomassenschwimmschicht and behind the agitator means.

9. Plant according to claim 1, characterized by a solids / liquid separation device (112, 212), the inlet of which is connected to a bottom outlet (110, 210) of the biogas production container (105, 205), while a liquid outlet of the solid / liquid separation device has an inlet (122, 222) near the open end of the chamber portion (114, 214), with an outlet (121, 221) for the clarified liquid near the bottom of the chamber portion.

10. A method for generating biogas from liquid and solid components containing organic, biodegradable material, such as waste products, especially manure from farms, in which one fills a biogas production container with the biodegradable material up to a certain level and this level substantially maintains level discloses flotation separation for separating solid constituents of the biodegradable material into a substantially gravity-directionally closed-bottomed chamber portion within the biogas production container and having an open top located below the liquid level level by creating microbubbles in the chamber portion , and the microbubbles formed in the chamber area countercurrent to the biodegradable material flowing into the chamber area via its upper end so that its solid components are entrained upward by the microbubbles, while liquid substantially clarified by solid constituents near the bottom of the chamber area is removed.

11. The method according to claim 10, characterized in that the biodegradable material prior to introduction into the biogas production container of a mechanical pre-separation into solid and liquid components are subjected.

12. The method according to claim 10, characterized in that the biodegradable material is introduced into the biogas production container and a quantity of or- ganic material is removed from the biogas production tank and subjected to mechanical separation into solid and liquid components.

13. The method according to claim 12, characterized in that the liquid obtained from the mechanical separation is divided into first and second subsets, wherein the first subset is greater than the second subset, in the second subset of the gas, in particular biogas from the biogas collection space is introduced to obtain a gas-charged liquid introduced into the chamber area near the bottom end thereof, while the first subset is introduced into the chamber area near its upper end, and liquid clarified near the bottom of the chamber area is taken from a time amount which is smaller than the first subset and greater than the second subset and smaller than the sum of the first and second subsets, so that the first subset in the chamber area causes a division into directed to the bottom and the open end liquid streams becomes.

A method according to claim 12, characterized in that the liquid obtained from the mechanical separation is introduced into the chamber area near its upper end, the microbubbles are formed in the chamber area near its bottom, and the chamber area near its bottom clarified liquid in a time amount which is smaller than the amount of liquid obtained from the mechanical deposition, so that it is caused in the chamber area to a distribution of directed towards the bottom and the open end liquid streams.

15. The method according to claim 13 or 14, characterized in that the introduction of the liquid obtained from the mechanical deposition takes place in the upper third of the longitudinal extension length of the chamber region.

16. biogas production container for use in a system according to claim 1, comprising a feed for liquid and solid components containing biodegradable material, such as waste products, especially manure from farms, a delimited in the interior of the biogas production container, substantially effective in the direction of gravity chamber area (14,114 ) having a closed bottom and an open top, wherein the biogas generation container is fillable to a level above the upper open end of the chamber region, at least one inlet (18, 123) near the bottom of the chamber region over which a microbubble forming liquid is insertable into the chamber region , and an outlet (16, 121) for clarified liquid near the bottom of the chamber area.

17. biogas production container for use in a plant according to claim 1, comprising a feed for liquid and solid constituents containing biodegradable material, such as waste products, in particular manure from farms, a delimited in the interior of the biogas production container, substantially in the direction of gravity effective chamber area (214 ) having a closed bottom and an open top end, the biogas generation container being fillable to a level above the upper open end of the chamber area, a microporous ceramic substrate material (229) positioned near the bottom of the chamber area, an inlet (228) for a pressurized gas into the microporous ceramic substrate material, and a clarified liquid outlet (221) from the chamber area near the bottom thereof.