RU2383497C1 - Device and method of producing biogas from biodegradable material containing liquid and solid components, particularly production wastes, as well as reservoir for producing biogas for use in said device - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: device has a reservoir 9 for producing biogas with supply of biodegradable material and a zone 11 for collecting biogas with an outlet of biogas and apparatus for producing micro-bubbles 15. The foam separation device has a chamber area 14 bordered inside the reservoir 9 for producing biogas. Clarified liquid from the chamber area 14 and gas, specifically biogas from the biogas collection zone 11, can be fed into the device for producing micro-bubbles 15 for saturating the liquid with gas. The outlet of the device for producing micro-bubbles is connected to the inlet 18 of the chamber area 14 so as to feed back clarified liquid forming micro-bubbles. Near the bottom of the chamber area 14 there is an outlet 16 for clarified liquid. Foam separation is carried out in the chamber area in counterflow to the micro-bubbles.

EFFECT: compact device, increased efficiency of the method with respect to output of biogas per unit time, and reduced production and investment expenses.

23 cl, 7 dwg, 2 ex

Description

The invention relates to a plant and method for producing biogas from liquid and solid components of organic biodegradable material, in particular production waste, such as slurry from agricultural enterprises, and also to a tank for biogas production for use in such a plant.

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

The known installation (US 5015384 A) contains a biogas production tank, from the upper zone of which biogas can be taken, and a flotation separation device provided outside the tank. The liquid biomass withdrawn from the reservoir together with the gas can be supplied to a device for the formation of microbubbles intended to separate solids from the biomass. The latter are again fed into the tank, while the purified liquid can be discharged for further use. Thus, flotation separation is carried out outside the tank for biogas production in a separate flotation separator.

The objective of the invention is to create a plant for the production of biogas, having a compact design, and a corresponding method of increased efficiency in relation to the output of biogas per unit time with a reduction in production and investment costs.

This problem is solved by paragraphs 1 and 8 of the claims.

A distinctive feature of the invention is the flotation separation into liquid and solid components inside the biogas tank by means of a chamber zone limited therein. The chamber zone contains clarified liquid that can be pumped out from the bottom of the chamber zone. At the same time, there is a continuous exchange of separated solid biomass from the chamber zone for mixing with production waste and production waste in the chamber into the chamber zone, and for this, separate supply and discharge systems are not required. Thus, there is a constant concentration of anaerobic biomass for biogas production, as a result of which the efficiency of the installation is increased. The production of microbubbles in the chamber zone can be carried out according to an embodiment of the invention due to the fact that the diverted partial stream of clarified liquid from the chamber zone is supplied to the gas saturation device and the gas-saturated liquid is again supplied to the chamber zone, where gas due to expansion effects is released in the form of micro bubbles. According to another embodiment, gas can be introduced into the porous substrate in the chamber zone, which exits from the substrate in the form of micro bubbles. It is required to create as small microbubbles as possible in order to capture most of the solid biomass due to the action of surface tension and to ensure its ascent in the chamber zone. The limited chamber zone ends at a sufficient distance below the liquid level in the biogas tank. Consequently, the supplied production waste flows from above to a limited area in countercurrent with respect to rising micro bubbles.

The biodegradable material is preferably, before or after being introduced into the biogas production tank, subjected to additional mechanical separation into liquid and solid components, preferably by means of a screw press separator. Moreover, according to another embodiment of the invention, the liquid components obtained after mechanical separation can be divided into various partial volumes and returned back to the chamber zone. As a result of this, a certain preferred section of fluid flows of different volumes directed towards the bottom and the open end of the chamber zone in countercurrent to rising micro bubbles occurs, which can lead to a further increase in the installation efficiency. According to another aspect of the invention, a reservoir for biogas production is provided.

Further, the invention is explained in more detail using examples and drawings, where:

Figure 1 is a schematic view in partial section of a biogas plant according to a first embodiment of the invention, which is integrated in a plant for separating slurry from agricultural enterprises into liquid and solid components,

FIG. 2 is a view and conditions similar to FIG. 1 for a biogas plant according to a second embodiment of the invention,

Figure 3 is an enlarged fragmentary view of the limited area of the biogas tank of figure 2,

Figure 4 is a top view in cross section of a limited area of the biogas tank of figure 3,

5 is a view similar to FIG. 1 of a biogas plant according to a third embodiment,

Fig.6 is a top view in cross section similar to Fig.4, a limited area of the biogas tank of Fig.5 and

Fig.7 is a top view in cross section of a limited area of the biogas tank of Fig.5.

Despite the fact that the description of the invention and its presentation in the drawings is given in connection with the production of biogas obtained from agricultural enterprises as a by-product of slurry, this application should not be construed as limiting the scope of protection of the invention. Moreover, it can also have a preferred application for producing biogas from materials and waste from other sources, in particular utilities and industrial enterprises.

As shown in FIG. 1, in a first embodiment of the invention, the slurry obtained in the stalls, which may contain liquid and solid components, is sent through a pipe 1 to a collector 3 and therein can be homogenized by means of a mixer 4. To supply a homogenized slurry from a collector 3 a pump 5 is provided on the separator 6 of the solid phase from the liquid. The separator 6 of the solid phase from the liquid is mainly a screw press separator, as described, for example, in EU-B-0367037, so that it can be referenced when further details. If desired, other designs of solid phase separators from the liquid can also be used.

The solid phase separated in the separator 6, indicated by 7, is collected and it can be delivered as fertilizer, if necessary in the form of compost, to the fields or after appropriate aerobic treatment used as bedding material in the stalls.

The liquid phase of manure freed up to a large extent from solid components is fed via line 8 to a biogas tank or to a biogas fermenter 9 of a biogas plant made in accordance with the invention. A stirrer 10 is provided in the tank 9 so as to constantly mix the liquid contained in it, indicated by dash-dotted lines in the drawing.

Instead of the agitator 10, or in addition to it, forced circulation (not shown) can also be provided by means of a circulation pump, which is sucked from the reservoir and again tangentially directing liquid into it.

The formation of biogas is carried out by fermentation of biomass in the presence of anaerobic bacteria, as the specialist knows in principle, so a more detailed explanation of this process is unnecessary.

Despite the fact that this is not shown in the drawing, another separation of the solid phase separator 6 and the solid fine particles of the substance still present in the liquid product of the separator 6 may be provided, for example, in the form of small sand components. Preferably, if this separation can be carried out by means of a centrifugal separator integrated in the pipe 8. An additional separation ensures that biologically indestructible sludge deposits are not formed in the tank 9 for biogas production.

The resulting biogas is collected, as shown by dashed lines in the drawing, in the upper film-coated or the like zone 11 of the reservoir 9, which serves as the biogas accumulator. From there, biogas can be diverted via line 12 for other purposes, for example, for producing current using a gas microturbine.

According to the invention, inside the reservoir 9, a dividing wall 13 is arranged upward, which in the reservoir 9 creates a bounded zone 14 open from above, cf. also figure 4. The separation wall 13 ends at an appropriate distance, for example within 0.5-1.0 m, below the liquid level in the tank 9, which is indicated by a dashed line in the drawing.

In the restricted zone 14, a new separation of liquid and still existing solid biomass is carried out according to the principle of flotation separation. To do this, through the pipe 16 near the bottom of the restricted area 14, the purified liquid is discharged outward and fed to the device 15 for the formation of microbubbles. A similar type of microbubble device is known to those skilled in the art. They serve to ensure that through the initial introduction of gas into the liquid under increased pressure, followed by intensive hydrodynamic rarefaction of the liquid in the cavitation field, to create the necessary microbubbles of gas for flotation separation. As a gas in the apparatus according to the invention, part of the biogas is withdrawn from the pipeline 12 and fed through the pipe 17 to the microbubble production device 15. In particular, by throttling the fluid flow in front of a centrifugal pump (not shown), biogas can be sucked in and pumped under pressure with a purified solution fluid. Due to the intense hydrodynamic rarefaction in the cavitation field, the dissolved gas again escapes from the liquid. In this case, microbubbles are formed in the micrometric range. The design of the device for the production of microbubbles is described, for example, in publication DE 3733583 A.

The clarified liquid saturated with gas is led back through a pipe 18 to a restricted area 14 near its bottom. Gas bubbles escaping from the liquid rise upward in the confined zone 14, while the biomass introduced through the conduit 8 into the reservoir 9 flows from above into the confined zone 14 in countercurrent to the rising micro bubbles. During the ascent, microbubbles take particles up in the liquid biomass with them so that a clarified and substantially deodorized liquid remains at the bottom of the restricted zone 14. In view of surface stresses, very small particles of biomass are also connected to microbubbles and transported upward by them.

The clarified liquid can be discharged to the outside through the pipeline 20 leaving the pipeline. Deaeration 21 may be provided to provide a permanent drain in the pipe 20 that does not require suction. 19 denotes the level of overflow installed by the pipeline 20, which determines the maximum filling height of the liquid biomass in the tank 9.

The mixer 10 supports the liquid biomass in motion throughout the tank and at the same time removes the solid biomass rising due to flotation from the confined zone and mixes it with the rest of the tank 9.

To maintain mixing of the separated solid biomass with the rest of the tank, the suction side of the mixer 10 can be equipped with a guide tube (not shown), which from the resulting floating biomass layer near the restricted area 14 can be led to the back of the mixer 10.

Figure 2-4 shows a second embodiment of the invention.

In this embodiment, as in the first embodiment described above, the slurry 100, consisting of liquid and solid components, enters in a certain quantity from stalls (not shown) into the collector 102; there, it can be homogenized with a stirrer 103. A pump 104 pumps fluid from a reservoir 102 into a biogas tank 105. The biogas 106 formed there accumulates under an accumulating film 107, which may be, for example, a PVC-coated polyester fabric 108. From there, the biogas can be diverted for other purposes.

In diametrically opposite locations of the biogas tank 105, a pair of mixers 109 may be provided to constantly mix the contents of the tank.

Inside the tank 105, as in the first embodiment of the invention, there is provided a dividing wall 113 spaced upward from the bottom of the tank, creating a restricted area 114 upwardly open in the tank 105, cf. also figure 4. The separation wall 113 ends at a certain distance, for example within 0.5-1.0 m below the liquid level in the tank 105, which is indicated by dashed lines in the drawing.

Through the suction pipe 110 from the bottom of the biogas tank 105, in a place outside the restricted area 114, the pump 111 can pump out the slurry and feed it to the solid phase separator 112 from the liquid. Preferably, the solid-liquid separator 112 is a screw press separator in the same manner as in the first embodiment.

The amount of slurry pumped out of the biogas tank 105 per unit time is according to the invention about 10-20% more than the throughput through the installation.

In the separator 112, solid components are separated from the slurry. The separated solid phase may, as indicated by 130, be collected for future use, for example, for transport on a trailer.

Most of the total volume of liquid leaving the separator 112 is piped 122 to a separate zone 114 of the biogas tank 105 at a suitable location near the upper open end, preferably, for example, within its upper third. As in the first embodiment described above, a centrifugal separator or other suitable separation device may be provided in line 122 to separate, for example, sandy, non-degradable bacteria components in a liquid.

A small partial stream of liquid flowing from the separator 112 is supplied to the microbubble formation device 115 and leaves the device in the form of a microbubble-filled liquid, which is supplied through a pipe 123 to the separated zone 114 to a suitable place near its bottom, preferably, for example, within the lower third .

A device for producing microbubbles 115 may have a similar construction as in the first embodiment of the invention. Preferably, a part of the biogas produced is also used as gas this time, as indicated by the dashed outlet pipe 127 in FIG. 2.

In a discharge line 121 provided near the bottom of the separated zone 114, liquid with a limited content of solid components can be discharged from the separated zone 114 of the biogas plant and collected for further use in the temporary storage 117. For example, the liquid collected in the temporary storage 117 through the exhaust pipe 118 can be sent to form of liquid fertilizer for agricultural purposes.

The biogas produced can be supplied via line 127 for further use, such as generating current or heat, to the block cogeneration plant 119. The waste heat can be used, as shown at 120, to stimulate biodegradation of the heating of the material contained in the biogas tank 105 through the heat exchange provided therein apparatus.

Below, with reference to figure 3, the flow paths resulting from the above-mentioned fluid supply in the restricted area 114 are explained.

A small partial flow rate flows through a pipe 122 to a restricted area 114, while a main flow flows through a 123, so that the sum of both partial volumes flows into a restricted area 114. A certain amount of liquid is pumped through a pipe 121 located near the bottom of the separated zone 114. limited solids content. In this case, the liquid coming from the pipeline 122 is divided into a partial stream 124 with a small flow rate, which flows back into the biogas tank 105, and a partial flow 125 with a high flow rate flows to the bottom of the restricted area 114 and is discharged outward through the exhaust pipe 121.

The microbubbles of the gas-saturated liquid volume brought through the pipeline 123 under the action of their lifting force move upstream against the partial flow 125 and are connected due to their surface tension to the solid biomass located in the partial flow 126, which, together with the partial flow 124, thus falls back into biogas reservoir 105.

Figure 4 shows a top view of the restricted area 114. As you can see, the separation wall 113 extends in an arcuate manner from one attachment point on the side wall of the biogas tank 105 to another attachment point spaced in the circumferential direction so that the restricted area 114 can have a substantially cross-section in segment shape. However, the invention is not limited to such a configuration of the restricted area 114, which may also be performed accordingly in another suitable manner.

Example 1

A solid phase separator 112 from the liquid accounts for a total of 10 m ³ / h of the separated liquid. It is divided into a larger partial volume of 9 m ³ / h and a smaller partial volume of 1 m ³ / h. A larger partial volume is supplied via line 122 to the upper third of chamber chamber 114, and a smaller partial volume after being saturated with gas through line 123 to the lower third. By pipeline 121, 8 m ³ / h of purified liquid is pumped out of the chamber zone. The flow rate per unit time of upward flow of liquid 124 in the chamber zone is 2 m ³ / h, and flow 125 downward is 7 m ³ / h. Therefore, the downward flow 125 and the partial flow rate 123 correspond to a total of 8 m ³ / h of the evacuated flow 121.

5-7 show a third embodiment of the invention. It differs from the second embodiment in a substantially modified way of microbubble formation in a limited chamber zone so that, with respect to the remaining structural elements, a description of the second embodiment can be referred to. Therefore, the same or similar parts / assemblies are indicated in the drawing by the same positions, but with the first digit changed to “2”.

The formation of microbubbles is carried out differently than in the above-described embodiments, not by means of a biogas device provided on the outside of the tank, but by means of a microporous ceramic disk-shaped substrate 229 provided inside it near the bottom of the restricted chamber zone 214 into which pressurized gas can be introduced via a pipe 228 rising from the microporous ceramic substrate 229 in the form of micro bubbles. Corresponding microporous ceramic substrate material can be purchased under the brand name Kerafol at Keramische Folien GmbH, Stegenthumbach 4-6, D-92676, Eschenbach / Germany. In turn, the gas is preferably biogas evacuated from the reservoir 205, which is mixed by means of the compressor 231, which is integrated in the pipeline 228, at an appropriate pressure, before it is supplied to the microporous ceramic substrate 229.

Example 2

A solid phase separator 212 from the liquid accounts for a total of 10 m ³ / h of separated liquid. Through conduit 222 is fed in its upper third chamber area 214. The pipeline 221 is evacuated from the chamber area of 8 m ³ / h of purified liquid. Biogas is supplied through a pipe 228 at a pressure of 2.2 bar to a microporous ceramic substrate 229. The flow rate per unit of upward flow of liquid 224 in the chamber zone is 2 m ³ / h, and downstream 225 is 8 m ³ / h.

Despite the fact that the gas supply to the device for producing microbubbles using the obtained biogas has been preferably described above, of course, corresponding extraneous gases from an external gas source can also be attracted.

Claims (23)

1. Installation for the production of biogas from containing liquid and solid components of an organic, biodegradable material, containing:
a tank (9, 105, 205) for the production of biogas with the supply of biodegradable material and a zone (11, 106, 206) for collecting biogas with the release of biogas, and
flotation separation device with a device (15, 115) for the production of microbubbles for separating solid components from liquid components of a biodegradable material,
wherein the flotation separation device comprises a chamber zone (14, 114, 214) with a closed bottom and below the liquid filling level of the biogas production tank, with an open upper end, which is limited inside the biogas production tank, and which acts essentially in the direction of gravity
wherein the device for the production of micro bubbles is made with the possibility of supplying gas, in particular biogas from the biogas collection zone, to create micro bubbles in the chamber zone. 2. Installation according to claim 1, characterized in that the device (15, 115) for the production of micro bubbles is located outside the tank (9, 105) for the production of biogas, with the possibility of supplying the purified liquid from the chamber zone to the device for the production of micro bubbles (14, 114 ) and gas to saturate the purified liquid with gas, while the release of the device for the production of microbubbles for gas-saturated clarified liquid is connected to the inlet (18, 123) of the chamber zone. 3. Installation according to claim 2, characterized in that the inlet (8, 123) for the gas-saturated clarified liquid is provided near the bottom of the limited chamber zone (14, 114). 4. Installation according to claim 1, characterized in that the device for the production of microbubbles contains located inside the chamber zone (214) microporous ceramic substrate (229), made with the possibility of introducing into it a gas under pressure. 5. Installation according to one of claims 1 to 4, characterized in that it contains a mixing device (10, 109, 209) located inside the tank (9, 105, 205) for the production of biogas for mixing the contents of the tank. 6. Installation according to one of claims 1 to 4, characterized in that in front of the tank (9) for biogas production it contains a device (6) for separating the solid phase and liquid for separating the solid components of the biodegradable material before feeding it into the tank for biogas production . 7. Installation according to claim 5, characterized in that in front of the tank (9) for biogas production it contains a device (6) for separating the solid phase and liquid for separating the solid components of the biodegradable material before it is fed into the tank for biogas production. 8. Installation according to claim 6, characterized in that the device (6) for separating the solid phase and the liquid contains a screw press separator. 9. Installation according to claim 7, characterized in that the device (6) for separating the solid phase and the liquid contains a screw press separator. 10. Installation according to claim 5, characterized in that the mixing device (10, 109, 209) contains a guide tube for suction of the floating biomass layer formed near the upper open end of the chamber zone (14, 114, 214) and its removal to the rear part of the mixing device. 11. Installation according to claim 1, characterized in that it contains a device (112, 212) for separating the solid phase and the liquid, the inlet of which is connected to the bottom outlet (110, 210) of the reservoir (105, 205) for the production of biogas, and the release of liquid a device for separating a solid phase from a liquid is connected to an inlet (122, 222) near the open end of the chamber zone (114, 214), while an outlet (121, 221) for the purified liquid is provided near the bottom of the chamber zone. 12. Installation according to claim 1, characterized in that the material for biogas production is a by-product of production, in particular slurry, from agricultural enterprises. 13. Method for the production of biogas from liquid and solid components of organic, biodegradable material, the implementation of which
the biogas production tank is filled with biodegradable material to a filling level above the open upper end of the inside of the biogas production tank, which acts essentially in the direction of gravity of the chamber zone with a closed bottom, and essentially maintain this level of filling,
flotation separation is carried out in the chamber zone to separate solid from liquid components of the biodegradable material, while microbubbles are produced in the chamber zone, and
they ensure the emergence of microbubbles produced in the chamber zone in countercurrent to the biodegradable material flowing into the chamber zone through its upper end so that the microbubbles take its solid components up along with the simultaneous removal of substantially liquid solid components near the bottom of the chamber zone. 14. The method according to item 13, wherein the biodegradable material is subjected to preliminary mechanical separation into solid and liquid components before being fed into the biogas production tank. 15. The method according to item 13, wherein the biodegradable material is fed into the biogas tank and part of the volume of organic material is taken from the biogas tank and subjected to mechanical separation into solid and liquid components. 16. The method according to clause 15, wherein
the liquid obtained from mechanical separation is divided into first and second partial volumes, wherein the first partial volume is larger than the second partial volume,
a gas, in particular biogas, is introduced into the second partial volume from the biogas collection chamber to obtain a liquid saturated with gas,
a gas-saturated liquid is introduced into the chamber zone near its bottom end while simultaneously introducing a first partial volume into the chamber zone near its upper end, and
clarified liquid is taken from the chamber zone near its bottom in a volume per unit time that is less than the first partial volume and greater than the second partial volume, and also less than the sum of the first and second partial volumes, with the separation of the first partial volume in the chamber zone into liquid flows directed to side of the bottom and open end. 17. The method according to clause 15, wherein
obtained by mechanical separation of the liquid is fed into the chamber zone near its upper end,
microbubbles in the chamber zone form near its bottom and
clarified liquid is taken from the chamber zone near its bottom in a volume per unit time that is less than that obtained by mechanical separation of the supplied liquid volume, with its separation in the chamber zone into liquid flows directed towards the bottom and the open end. 18. The method according to clause 16 or 17, characterized in that the flow obtained by mechanical separation of the liquid into the upper third of the longitudinal length of the chamber zone. 19. The method according to item 13, characterized in that as a material for biogas use a by-product of production, in particular dung, from agricultural enterprises. 20. The tank for the production of biogas for use in the installation according to claim 1, containing
supplying liquid and solid components of biodegradable material,
a chamber zone (14, 114) with a closed bottom and an open upper end, which is limited inside the biogas tank, essentially acting in the direction of gravity
wherein the biogas production tank is configured to be filled to a filling level above the upper open end of the chamber zone,
at least one inlet (8, 123) near the bottom of the chamber zone for supplying microbubbles of liquid to the chamber zone, and
outlet (16, 121) for clarified liquid near the bottom of the chamber zone. 21. The tank according to claim 20, characterized in that the material for biogas production is a by-product of production, in particular slurry, from agricultural enterprises. 22. The tank for the production of biogas for use in the installation according to claim 1, containing
supplying liquid and solid components of biodegradable material,
a chamber zone (214) with a closed bottom and an open upper end, which is limited inside the biogas tank, essentially acting in the direction of gravity
wherein the biogas production tank is configured to fill to a level of filling above the upper open end of the chamber zone,
a microporous ceramic substrate located near the bottom of the chamber zone,
an inlet (228) for the compressed gas into the microporous ceramic substrate and
outlet (221) for clarified liquid from the chamber zone near its bottom. 23. The tank according to claim 22, characterized in that the material for biogas production is a by-product of production, in particular slurry, from agricultural enterprises.

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