DE3427976C2 - - Google Patents

Description

The invention relates to a biogas reactor for anaerobic treatment of organic substrates for the production of biogas according to the preamble of claim 1.

Since the energy crisis in 1973 there has been a rethinking process in industry and initiated agriculture as the energy supply for many Farms became a question of profitability.

Through new technologies such as heat recovery, energy interconnection, Microelectronics, use of heat-insulating building materials, etc. substantial energy has already been saved. As an old one native energy sources such as geothermal and solar heat are particularly important for the invention described here, waste products in farmer commercial and industrial companies for discussion. These Waste products fall into the form of so-called bio-substrates liquid animal excrement - also called liquid manure - in the country farms, agricultural distilleries and Slaughterhouses, taking the vegetable substrates and biomass as stillage or wastewater with organically high dirt loads as well as vegetable waste in commercial distilleries, canning and Food factories arise.

In companies where the liquid manure from animals or waste water is present a high proportion of organic dirt there is the possibility to build a biogas plant, a corresponding share to cover the consumption of heating oil, To provide natural gas and electrical energy.  

It is a bio-energy plant, so one Plant that generates methane gas from the aforementioned substrates both in a water or steam boiler as well as in one Gasoline engine that drives a three-phase generator burned can be.

It is known that bacteria are degradable organic substances, So carbohydrates, proteins and fats both under oxygen dismantle as well as in the presence of oxygen or can degrade. In the present case, it is a process that in complete darkness and in the absence of oxygen in a substrate takes place; one also speaks of an anaerobic fermenta tion.

The mesophilic temperature range 32-38 ° C is up for discussion, the thermophilic temperature range 53-58 ° C predominantly at Substrates with dangerous pathogenic germs come into question. At the biomethanization of organic substances, which in four According to current knowledge, there are three phases different groups of bacteria involved. In the hydrolytic and Acid-forming process phases are anaerobic by the optional Bacteria with fermentative or acidogenic characteristics organically high molecular weight compounds with the help of enzymes low molecular weight compounds such as amino acids, glycerin and fat acids hydrolyzed, with the hydro lysis products vinegar, butter, propion, valerian, capron, Formic and lactic acid as well as ethanol, hydrogen, carbon dioxide, Ammonia and hydrogen sulfide are produced.

However, the composition of these metabolites is influenced to a corresponding extent by the hydrogen partial pressure. While more propionic acid is formed at a low H ₂ pressure or a medium room load, more valeric acid is produced at a high H ₂ pressure at a medium room load. In addition, a high hydrogen partial pressure acts as an inhibitor in the catalysis of acetic acid.

The acetic acid and hydrogen forming process phase is from the obligatory anaerobic bacterial strains, but with acetogenic Characteristic, adopted, the long of this group chain fatty acids, organic acids, alcohols and aromatics be broken down to acetic acid, hydrogen and carbon dioxide.

The starting product for the methane bacteria - these are also the obligatory anaerobes - which have a methanogenic characteristic are primarily acetic acid, hydrogen and carbon dioxide, which in the last instance are converted to methane gas (CH ₄ ) and carbon dioxide (CO ₂ ) will. It is interesting here that the methane bacteria need a redox potential of -330 m volts for growth, live in a spatially close symbiosis with the acetogenic bacteria, are sensitive to pH values and cannot tolerate fluctuating substrate temperatures. In addition, this community is particularly sensitive to shear forces such. B. by agitators. The presence of dissolved oxygen is also sometimes fatal to methane bacteria.

Since the H ₂ partial pressure in the substrate should be low, coupling reactions must take place, such as e.g. B.

4 H⁺ + 4 NAD (P) H → 4 NAD (P) ⁺ + 4 H ₂ + 18.4 E

4 H ₂ + CO ₂ → CH ₄ + 2 H ₂ O - 33.2 E.

Overall response

4 H⁺ + 4 NAD (P) H + CO ₂ → 4 NAD (P) ⁺ + CH ₄ + 2 H ₂ O - 14.8 E

NAD = nicotinamide adenine dinucleotide E = free energy (KJ / mol).

A special aspect for the reduction of the hydrogen partial pressure are the coenzymes found in the methane bacteria, in particular NAD, which ensure the reduction of the H ₂ pressure by means of a chemical osmotic metabolic process.

By reducing the H ₂ pressure there is also a corresponding influence on the free energy, that is to say that as the H ₂ partial pressure decreases, the conversion of organic compounds changes from an endergon to an exergon process.

Since the first process phases are so-called acidic biological process flow and the methane bacteria their life activity only in a weakly alkaline medium fold, it is therefore important that the individual Process phases are in a so-called equilibrium. Should namely, the organic acids accumulate, which is also due to the measured pH value can be determined, this is a Signs that for some reason the mining activity of the acid-producing bacteria that of acid-consuming bacteria outweighs and thus the balance is disturbed, d. that is, the Methane bacteria are paralyzed and the fouling process tips over, unless appropriate countermeasures to support the last process phase.

Are the organic substances in the substrate with a corresponding Degree of degradation biomethanized, the technical digestive limit is reached, d. that is, the substrate is sludged. That off muddy substrate - also called digested sludge - is almost smell go, largely hygienized, has an appropriate nutrient wealth and can continue to be used as fertilizer.

According to the previous points of view, the construction of Biogas plants primarily the so-called continuous reactor - also called inflow reactor - crystallized out. That reak gate works in one step, whereby the substrate is mixed. All four described bio-technologies run in this reactor phases in a room under the same physical conditions conditions. It is understandable that with this method none optimal living conditions for the individual bacterial strains available. In addition, there is a risk that the reactor  becomes acidic, d. that is, the pH drops to one for the methane bacteria below 7, as an excess production of acids is present.

The metabolic production of the corresponding degradation phase is also disturbed by the entry of toxic substances such as sulfonamides, copper, zinc and chromium compounds, etc. and the oxygen inhibitor. Another disruption of metabolic production can occur when substrates, e.g. B. stillage with high sulfate content, occur because the sulfate compound is reduced to hydrogen sulfide and thus the H ₂ S content formed can significantly impair the process.

If methane bacteria are killed or paralyzed, i.e. a disturbance of the acetogenic-methanogenic phase, less hydrogen is broken down, ie the H ₂ partial pressure increases. Since this acts as an inhibitor for the acetogenic bacteria, it must be expected that the metabolic production - especially of acetic acid - of these bacteria comes to a standstill and that more reduced products are formed by the H ₂ enrichment.

With a biological degradation of stillage, a hydrogen sulfide content in the biogas of approx. 2.5% must be expected, which means that this fuel gas cannot be burned in a gasoline engine without prior elimination of the H ₂ S content.

Another disadvantage is that with relatively long residence times of the substrate, only economical gas yields of about 1-2 m ³ / d biogas per m ³ digester or low degrees of degradation of the organic substances are possible.

The calorific value of the biogas is 7 KWh / m ³ _n with a gas composition of 70% methane (CH ₄ ), 29.7% carbon dioxide (CO ₂ ) and 0.3% in a single-stage reactor, which treats normal substrates anaerobically using modern process techniques. Hydrogen sulfide (H ₂ S).

Based on the above knowledge, it has already been proposed been a biotechnological separation into hydrolysis and Acid phase as well as in the methane formation phase to provide for the appropriate bacterial cultures optimal living conditions to create, cf. DE-OS 31 02 739.

It is important that the acid or methane formation phase does not take place in two separate reactors, since the formation of acetic acid is influenced by the H ₂ partial pressure in this system solution, but that the hydrolysis and acid phases combine in one Plays reactor. In this two-stage reactor, the hydrogen partial pressure in the acid reactor is reduced accordingly by the methane bacteria present, and the pH is accordingly adjusted, at the same time producing more acetic acid and an optimal composition of more degradable metabolites such as acetic, butter, caproic acid and ethanol . In this process technology, the H ₂ partial pressure is reduced in the form of a coupling reaction - which can also be referred to as mass transfer - by methane bacteria or the universal hydrogen carrier NAD and other coenzymes. In this coupling reaction, the diffusion flow of hydrogen molecules and electrons through the annular gap is decisive.

Another constructive point is the division of the fermen tion rooms I and II, i.e. the acid or methane formation phase with a volume ratio of preferably 1:10.

It is known that in an acidification stage, depending on the milieu conditions of the substrate, significantly more bacteria - due to the short generation times of the facultative anaerobes - are present, than in a methane reactor. Because of this knowledge there is an under different production ratio between acid and methane bacteria before or is a space load of the hydrolysis and Acidification reactor more than ten times as high as one stage reactor possible without a significant reduction in the he  produced metabolic products or degrees of degradation in stage I occurs. In addition, with a high space load pH adjustment ensures extensive stability of the produced Metabolic products are expected. Even the composition and distribution of the metabolic products produced such as vinegar, Butter, Valerian, Capronic, formic and lactic acid as well as ethanol, Hydrogen and carbon dioxide, can be in fermentation stage I at the mesophilic temperature of 30 ° C in the pH range of 5 to 6 using the described method and the fixed room layout and high space load of the hydrolysis and acidification level are expected to be optimal. At a pH value of 5-6 is with a max. Acid growth rate forming bacteria. The metabolic products individually produced in the acid reactor can be faster and better in the end pro in the methane reactor Duct to convert methane gas and carbon dioxide, using the hydrogen utilizing methane bacteria their full performance in the Can unfold fermentation stage II. With this procedure the metabolic performance of the individual breakdown phases are essential Lich higher than in a single-stage reactor or is due to the lower Carbon investment in bacterial culture more methane synthe tized.

In addition, due to the procedural process control in the methane reactor, there is an increased adaptation of the symbiotic population of CO ₂ -processing methanogenic bacterial strains, ie the formation of acetic acid in fermentation stage II takes place according to the following equation.

2 CO ₂ + 4 H ₂ → CH ₃ COOH + 2 H ₂ O

This consequence lowers the partial pressure of CO ₂ and enables a higher acetate conversion to methane gas.

CH ₃ COOH → CH ₄ + CO ₂ - 32 E.

DE-GM 81 29 366.6 shows a device for processing a biomass to biogas with an acid container as the first Reactor room and a digester as a second reactor room. The gas spaces of both heatable containers are open bond with each other, with no direct connection of the Substrate in the acid container with the substrate in the digester consists. The biomass is placed in the central acid container and from there it gets into the Digestion tank in which a circulation of the biomass to be gasified takes place and a temperature of 37 ° C to 56 ° C is set. The known device has disadvantages. As already described ben, takes place in the first reactor room (acid container) by hydro lytic and acidifying (fermentative) and acetic acid and Ultimately, hydrogen-forming (acetogenic) bacteria essentially breakdown of the biomass to acetic acid, hydrogen and carbon oil dioxide. Acetic acid is the main raw material for methano bacteria, from which around 70% of the methane gas is generated. Acetic acid that has not gone into solution collects due to its relatively higher density weighing near the ground, which means that through the known Acetic acid overflow system only partially in the second reactor room is transferred, lighter and difficult to break down metabolism pro products, however, in relatively large quantities. This means bigger ones Residence times and a lower methane yield and thus one reduced degree of degradation of organic substances. Through the gas Establish a moderate connection between the gas spaces of the two reactor rooms with regard to all gases that arise, in particular be plus methane, carbon dioxide, hydrogen and sulfur water substance, same gas partial pressures of the ge in solution in the substrate received gas, d. that is, the endergons or exergons Biosynthesis steps in both fermentation rooms are completely the same run, and therefore a separation of the hydrolyzing-acidifying the phase of the acetogenic-methanogenic phase does not occur is coming. It is therefore a scarf in a row tion of two single-stage methane reactors, since in the Acid reactor cannot set a pH of 5. The before The presence of hydrogen sulfide is also due to the adverse effect on the methanogenic bacteria.

The object of the present invention is now to a biogas reactor of the type mentioned at the beginning  improve that a higher degree of degradation with short dwell times is achieved as well as a larger proportion of high-quality methane is synthesized.

This task is ge through the training according to the characterizing part of claim 1 solves. Advantageous and expedient developments are in the Subclaims specified.

Due to the inventive design, a continuous reduction of the hydrogen partial pressure via the annular gap or the settled products takes place in the first reactor space, in connection with the intended mechanical circulation according to the circular principle in the hydrolysis and acidification stage a more uniform and for that Bacterial growth optimal hydrogen partial pressure - which corresponds to a pH value of 5-6 - builds up. The invention synthesizes an increased proportion of acetic acid in the first reactor space and produces it in the second reactor space, thus largely preventing the less desirable production of propionic and valeric acid. The complete separation of the gas space of the first reactor space, in which a gas with a composition of approx. 97% CO ₂ and 3% H ₂ S is formed, depending on the type of substrate, from the gas space of the second reactor space, in which a gas with a composition Developed from approx. 80% CH ₄ and 20% CO ₂ , guarantees the setting of individual or optimal gas partial pressures in the substrate. The high proportion of CO ₂ in the first reactor space results in a lowering of the pH in the substrate. In the two-stage process designed according to the invention, the hydrolyzing acid-forming bacteria are separated from the acetogenic-methanogenic bacteria and optimal living conditions are created for the microorganisms, ie that the corresponding bacteria can develop their full potential and therefore the residence times of the substrates in the combined reactor are reduced. In addition, under these biotechnological conditions, a smaller amount of carbon is synthesized into the cell substance of the bacterial population. There is thus a higher degree of degradation of the organic substances and a higher yield of methane, with a methane content in the biogas of over 80% being achievable. The biogas produced is almost completely free of the undesirable proportion of hydrogen sulfide generated in the first reactor room.

When charging the first reactor space, the produ adorned metabolic products of the first fermentation stage through the annular gap, be the second with activated sludge Fermentation stage of the second reactor room in the mixing injector gentle on the substrate, d. H. without the action of shear forces, mixed and enclosed by the cylindrical wall its cylindrical chamber in the second reactor chamber in a circle promoted with backmixing, creating an excellent ver division of metabolic products for a high-grade and rapid degradation is achieved.

The double-walled cylinder wall has additionally the function of thermal insulation, in particular through the biogas supplied through the gap. Because of the warmth Insulation is achieved in particular in the reactor rooms be operated with different substrate temperatures can. This is important as for hydrolyzing and Acidification of the organic substances a temperature of 30  up to 32 ° C is optimal and in the acetogenic methanogenic phase a temperature of 35 to 37 ° C is optimal.

Through the raised cone bottom of the first reactor space ge According to claim 2, no sedimentation layers can form the. The promoted in the first reactor room and not mining Bare substances slide on the cone into the second reactor room and can be desludged or discharged from there.

The jet pump according to claim 3 with the side open Nozzle mixing chamber sucks substrate from below from the first Fer mentation room, whereby the ratio of activated sludge to fed fresh substrate preferably at least Is 3: 1. The substrate circulation takes place in a circle with back mixture. At the same time the Jet pump broken up a possibly formed floating blanket and dissolved. In addition, during the hydraulic Circulation of the sedimented material in the lateral cone bottom Exchange products not disturbed or whirled up.

In the case of biogas reactors with a content of less than 300 m ³ , the first reactor space is in the middle of the second reactor space. In biogas reactors with a content greater than 300 m ³ , several individual reactor rooms are normally used for the most fermentation process, as stated in claim 3.

The invention is based on the Drawing will be explained in more detail. It shows

Fig. 1 shows a section through an inventive design biogas reactor,

Fig. 2 shows diagrammatically a horizontal section through an inventive biogas reactor having a plurality of reactor chambers for the first Fermanentationsprozeß,

Fig. 3 shows schematically the formation of the heat exchangers provided in the biogas reactors according to FIGS. 1 and 2

Fig. 4 shows a preferred embodiment of a mixing injector provided in the biogas reactor according to the invention.

The drawing shows a combined biogas reactor with a first reactor room 1 and a second reactor room 2 . In the first reactor space, which is arranged within the second reactor space, a first fermentation process (hydrolysis and acid formation) and in the second reactor space, a second fermentation process (methane formation) takes place.

The first reactor chamber 1 has a raised base with a conical base surface 19 and is formed by a double-walled cylinder 8 , between the walls of which an annular cylindrical intermediate space 40 is formed. The cylinder 8 ends above the conical bottom 19 , so that an annular gap 11 is formed between the cylinder 8 and the bottom 19 , through which the first reactor chamber 1 is in open connection with the second reactor chamber 2 . The lower part of the double-walled cylinder 8 is designed as a mixing injector 10 .

The cylinder wall 8 is surrounded by a further cylinder 9 at a distance, so that a cylindrical annular chamber 44 is formed which is designed as an overflow chamber and ends at a distance from the bottom of the second reactor space 2 , so that a further annular gap 46 is formed which, like the annular gap 11 leads into an injection mixing chamber 45 , which is delimited by the conical base 19 , the cylindrical wall 9 and the mixing injector 10 . Via the intermediate space 40 , biogas can be fed to the mixing injector under pressure by means of a gas compressor 5 . The suction port of the Gasver poet 5 is connected to a biogas chamber 42 of the reactor chamber 2 and the pressure port of the gas compressor is connected to the space 40 of the double wall cylinder 8 .

The lower end of the cylinder 9 is formed as a heat exchanger 12 . With the help of the mixing injector 10 , a hydraulic circulation circulation of the substrate in the reactor space 2 is brought about, as is indicated by the line 48 . A further thermal circulation of the substrate is brought about by the heat exchanger 12 . This thermal circulation overlaps the hydraulic circulation.

In the reactor chamber 1 , a jet pump 7 with a laterally open nozzle mixing chamber is arranged centrally above the cone bottom 19 , which sucks the substrate in the reactor chamber 1 from below and pumps it upwards. The jet pump 7 is surrounded by the coil of a tubular heat exchanger 6 , which thus acts as a guide tube, as well as the annular intermediate chamber 44 , whereby a hy metallic circular circulation of the substrate in the reactor chamber 1 is effected, as indicated by the lines 50 . This hydrau lic circulation is superimposed by a thermal circulation, which is caused by the heat exchanger 6th

The flow and return connections of the heat exchangers 12 and 6 are designated by the reference numerals 15 and 20 or 16 and 18 . The coiled heat exchanger tubes 23 are preferably made of plastic (for example polypropylene) ( FIG. 3). Two individual U-shaped tubes 24 each serve as the support structure, which simultaneously form distributor tubes for the flow and the return. The tubes are guided through the reactor wall by means of adjustable tube bushings 26 . A vent valve is designated by the reference numeral 25 . The substances biodegraded in the fermentation room 2 collect in the surrounding funnel-shaped bottom 29 .

In the reactor chamber 2 , two discharge nozzles 13 and 14 are arranged, which can optionally be connected via a three-way valve 21 to a double U-tube 22 for discharging biodegradable sub strates. Discharge nozzle 13 is located near the bottom and the discharge nozzle 14 is approximately halfway up the reactor space 2 . The first U-tube leg 28 is connected to the biogas chamber 42 via a line 30 .

The resulting biogas in the reactor chamber 2 CH ₄ + CO ₂ is connected via a shut-off element 3 and the resulting acidic biogas in the reactor space 1 CO ₂ + H ₂ S can be derived via a differential pressure-controlled overflow valve. 4

In reactors with a content of less than 300 m ³ , a single reactor space is used for the first fermentation process, which is arranged centrally in the reactor space 2 for the second fermentation process, cf. Fig. 1. In reactors with a content of more than 300 m ³ several, for example three individual reactor rooms 32, 34, 36 are used for the first fermentation process, which are evenly distributed in the reactor room 2 for the second fermentation process, cf. Fig. 2, the area of action of the individual reactor rooms is set so that it has an operating radius in 3 reactor rooms, which makes up about 25% of the total diameter of the reactor 2 .

The two-stage reactor shown in the drawing is built in a space ratio of the first reactor space 1 for the acid formation phase to the second reactor space 2 for the methane formation phase of about 1:10.

The biogas reactor shown in the drawing works as follows. The first reactor chamber 1 is fed with the substrate to be treated via a gate valve 17 . With the help of the jet pump 7 , the substrate is hydraulically circulated, a ratio of activated sludge to the fresh feed substrate being set to at least 3: 1. The loading takes place via an external pump, which is not shown. This pump is connected to the gate valve 17 and the jet pump 7 . During the feed, which takes place quasi-continuously, activated sludge is sucked in by means of the jet pump 7 , which is provided with lateral slots on the nozzle mixing chamber, and mixed with the fed substrate. In the process, activated sludge continuously flows into the heat exchanger from below during the charging process. After loading the reactor chamber 1 , the heat exchanger 6 is started up by the temperature drop that has occurred in order to set the intended optimum temperature of approximately 30 ° C. and to keep it constant. By switching on the heat exchanger, as already mentioned, a further circulation takes place in the form of a thermal circulation of the substrate.

During the loading of the reactor chamber 1 , the metabolic products accumulated in the cone-bottom region 19 are conveyed via the annular gap 11 into the injection mixing chamber 45 and mixed with activated sludge from the reactor chamber 2 and conveyed into the reactor chamber 2 via the intermediate ring chamber 44 and distributed accordingly by simultaneous circulation . , The activation of the heat exchanger 12 is performed simultaneously by the temperature drop in the reactor compartment 2, which is operated with an optimum temperature of about 35 ° C. After the gas compressor 5 or the mixing injector 10 has been switched off, the reactor space 2 is also thermally circulated through the space 44 by the action of the heat exchanger 12 . An arrangement of gas compressor 5 , annular space 40 as a guide tube, mixing injector 10 and annular intermediate chamber 44 as a further guide tube is also referred to as a mammoth pump.

Due to the hydraulic and thermal circulation of the substrate in the reactor chamber 2 , a reduction of the hydrogen partial pressure in the sedimentation area of the reactor chamber 1 is carried out via the annular gap 11 . The biogas generated in the reactor room 2 (CH ₄ + CO ₂ ) is removed via the shut-off device 3 and supplied to the United States. The acidic biogas (CO ₂ + H ₂ S) generated in the reactor chamber 1 can be discharged via the control valve 4 .

After appropriate biodegradation of the organic substances, they collect in the funnel-shaped bottom 29 or the digested sludge is discharged from the reactor chamber 2 via the discharge nozzle 13 or 14 according to the fresh substrate quantity fed into the reactor chamber 1 . The discharged digested sludge flows through the double U-tube 22 , which also serves as a siphon for storing compressed gas, through the connection to the biogas chamber 42 with the aid of the connecting line 30 .

To achieve a favorable reactor efficiency at A ratio becomes the lowest possible material consumption between the height and diameter of the reactor of about 2: 1 chosen.

Furthermore, the height of the annular gap 11 can be adjusted subsequently using the device 27 .

To at various reactor pressures - taking into account the data stored in the fermentation chamber 2 with compressed gas quantity - to achieve a constant digester volume is controlled by a differential pressure control, which is performed between the fermentation chamber 1 and fermentation space 2, produced in the fermentation chamber 1 excess biogas (CO ₂ + H ₂ S ) drained through the overflow valve 4 .

For special cases, the drain line of the overflow valve 4 can be connected to the removal line 3 . In this case, depending on the type of substrate, the gas must be cleaned via a Gaswaschvor device or desulfurization system.

As already mentioned above, the lower part of the double-walled cylinder 8 is designed as a mixing injector 10 . Via this mixing injector, biogas is blown into the reactor space 2 under pressure, specifically through holes 60 leading into the reactor space. The mixing injector is formed by the lower part of the inner wall of the cylinder 8 , one at an angle to this inner wall upwards into the reactor chamber 2 , the circumferential bottom 62 and by an from the outer wall of the cylinder 8 at an angle to the outside in the reactor space revolving part 64 which is connected to the bottom 62 of the. The holes 60 are formed in this part 64 near the connec tion point with the bottom 62 . The angle between the bottom 62 and the inner wall of the cylinder 8 is approximately 46 ° and the angle between the outer wall extension of the cylinder 8 and the part 64 is approximately 18 °. This configuration forms a cross-section approximately triangular ring-shaped annular space in the lower part of the double-walled cylinder 8 as a mixing injector. The holes 60 are distributed around the circumference. Several rows of holes with mutually offset holes can be provided. In the drawing ( Fig. 4) two rows of holes are indicated schematically. The holes preferably have a diameter of about 4 mm. From the lower acute-angled end 66 of the mixing injector, several drainage pipes 68 are guided upwards, which end in the bottom 62 and end approximately at the height of the holes 60 , preferably at a short distance from the holes.

Claims (22)

1. Biogas reactor for the anaerobic treatment of organic substrates for the production of biogas with a first reactor space for the conversion of an organic substrate into metabolic products, primarily in acetic, butter or caproic acid and hydrogen and carbon dioxide, further with a second, the first reactor space surrounding the reactor space for converting the metabolic products formed in the first reactor space into biogas (methane and carbon dioxide), wherein in the first and / or second reactor space facilities for circulating the substances and heating devices located in the reactor spaces are arranged, characterized in that the first reactor space ( 1 ) and the second reactor space ( 2 ) are connected to one another via an annular gap ( 11 ) in the bottom region of the reactor spaces that
the upper parts of the two reactor spaces forming the gas spaces are separated from one another in that
the first central reactor chamber ( 1 ) with a double-walled be spaced to the bottom of the reactor chamber ending cylinder wall ( 8 ) is formed, the lower end of which is formed as a mixing injector ( 10 ) and, via the intermediate space ( 40 ), part of the biogas it produces under pressure from above the mixing injector bar for mixing the metabolic products generated in the reactor chamber ( 1 ) with activated sludge of the second reactor chamber ( 2 ) and to promote the mixture in the second reactor chamber, and that
the mixture is conveyed into the second reactor chamber via an annular cylindrical chamber ( 44 ) designed as an overflow chamber, which is formed by the cylinder wall ( 8 ) and a cylindrical wall ( 9 ) which is spaced apart and is arranged in the second reactor chamber ( 2 ), which ends below the mixing injector ( 10 ) at a distance from the bottom of the reactor space ( 2 ) and above it. 2. Biogas reactor according to claim 1, characterized in that the first reactor chamber ( 1 ) has a raised bottom with a conical bottom surface ( 19 ), that the annular gap ( 11 ) between the lower end of the cylinder wall ( 8 ) and the conical bottom ( 19th ) is formed, the products produced in the most reactor chamber ( 1 ) passing through the annular gap ( 11 ) into an injection mixing chamber ( 45 ) formed below the annular gap, which is limited by the conical bottom ( 19 ), the lower part of the cylindrical wall ( 9 ) and the mixing injector ( 10 ). 3. Biogas reactor according to claim 1, characterized in that a jet pump ( 7 ) is arranged for circular substrate circulation in the first reactor chamber ( 1 ), which has a laterally open nozzle mixing chamber. 4. Biogas reactor according to claim 1, characterized in that a vertically arranged, rohrför shaped heat exchanger ( 6 ) is arranged in the first reactor chamber ( 1 ) for temperature adjustment. 5. Biogas reactor according to claim 3 and 4, characterized in that the jet pump ( 7 ) is arranged within the heat exchanger ( 6 ). 6. Biogas reactor according to claim 2, characterized in that the lower part of the cylindrical wall ( 9 ) is formed by a heat exchanger ( 12 ). 7. Biogas reactor according to claim 1, characterized in that the biogas is supplied with the aid of the gas compressor ( 5 ), the pressure connection to the intermediate space ( 40 ) and the suction connection to the biogas chamber ( 42 ) of the reactor chamber ( 2 ) is connected. 8. Biogas reactor according to claim 1 or 2, characterized in that the annular gap ( 11 ) by a device ( 27 ) which is connected to the reactor space ( 1 and 2 ) is adjustable in height. 9. Biogas reactor according to claim 1 or 2, characterized in that the mixing injector ( 10 ) through the lower part of the zy-cylindrical inner wall of the double-walled cylinder ( 8 ), by an at an acute angle from the end of the cylindrical In nenwand up in the Circulating bottom ( 62 ) facing the reactor space ( 2 ) and a peripheral part ( 64 ) pointing at an acute angle from the cylindrical outer wall of the cylinder ( 8 ) down into the reactor space ( 2 ) is formed, which with the bottom ( 62 ) is connected and in which a plurality of holes ( 60 ) are formed all around. 10. Biogas reactor according to claim 9, characterized in that the holes ( 60 ) are arranged just above the junction of the part ( 64 ) with the bottom ( 62 ). 11. Biogas reactor according to claim 9 or 10, characterized records that several spaced rows of holes with offset mutually arranged holes are provided. 12. Biogas reactor according to claim 9, characterized in that in the acute-angled end ( 66 ) of the mixing injector ( 10 ) a plurality of drainage pipes ( 68 ) are arranged which are guided upwards in the bottom ( 62 ) and at the height of the holes ( 60 ) end up. 13. Biogas reactor according to one of claims 1 to 12, characterized in that the first reactor space ( 1 ) consists of several individual cylindrical reactor spaces which are arranged within the second reactor space ( 2 ). 14. Biogas reactor according to claim 13, characterized in that three identical, individual cylindrical reactor subspaces ( 32, 34, 36 ) are provided. 15. Biogas reactor according to claim 14, characterized in that the individual cylindrical reactor subspaces are divided so that the area of action of each reactor subspace has a Ra dius, which makes up about 25% of the diameter of the second reactor space ( 2 ). 16. Biogas reactor according to one of claims 1 to 15, characterized in that the ratio of the volume of the first rector space ( 1 ) to the volume of the second reactor space ( 2 ) is 1: 2 to 1:20, but preferably 1:10. 17. Biogas reactor according to one of claims 1 to 16, characterized characterized that the ratio height: diameter of the bio gas reactor is about 2: 1. 18. Biogas reactor according to one of claims 1 to 17, characterized in that the annular bottom of the second reactor space ( 2 ) is formed funnel-shaped downwards. 19. Biogas reactor according to one of claims 1 to 18, characterized in that the first reactor chamber ( 1 ) with its cylinder wall ( 8 ) and the cylindrical wall ( 9 ) is designed as an insert which can be pulled out upwards. 20. Biogas reactor according to claim 9, characterized in that the angle between the bottom ( 62 ) and the cylindrical inner wall of the cylinder ( 8 ) about 46 ° and the angle between the extension of the cylindrical outer wall of the cylinder ( 8 ) and the part ( 64 ) is approximately 18 °. 21. Biogas reactor according to claim 4, characterized in that the heat exchanger has U-shaped supply and return pipes ( 24 ), which serve as a support structure, distributor pipes and ventilation pipes and between which a coiled tubing ( 23 ) is arranged. 22. Biogas reactor according to claim 1, characterized in that an overflow valve ( 4 ) is connected to the gas space of the first reactor space ( 1 ) for regulating the same gas pressures in the separate gas spaces.