MD4244C1 - Combined anaerobic reactor for the production of biomethane - Google Patents

Abstract

The invention relates to plants for biomethane production in the biogas composition and can be used in different branches of agriculture and processing industry.The combined anaerobic reactor for the production of biomethane consists of a bioreactor (2) with a cylindrical body (1) with conical bottom, connected to a sludge removal nipple (3). In the bioreactor (2) is placed a load (4) for the attachment of microflora and a level gauge (5). In the upper part of the bioreactor (2) is placed a reservoir (10), provided with a level gauge (6) and a flap (9) with a float (8). On the reservoir (10) is placed an electromagnetic mixer (11), containing metallic particles (14), a generator (15) of rotating electromagnetic field, a liquid supply nipple (12) and a valve (13) for liquid drainage in the reservoir (10). In the lower part of the bioreactor (2) is mounted a receiver (17), provided with an automatic level gauge (18), connected to a control unit (19), coupled with a pump (20), equipped with a liquid-methane ejector (21), which, through a bio-methane extraction conduit (24), communicates with the upper part of the bioreactor (2). The ejector (21) is connected to a sprayer (25) and an aspirator (23). In the lower part of the receiver (17) is coupled a nipple (26) with a regulating valve (27) and a recirculation conduit (28), connected to a pump (29), which is coupled with the control unit (19) and connected to a liquid ejector (30), connected to an electric generator (31) with hydrogen diaphragm and a perforated distributor (33). In the upper part of the receiver (17) is mounted a hose (34), connected through a siphon (35) to a suction chamber (36), filled with activated coal (37), attached to the body (1) and provided with a driving device (38) with vibration and a methane drainage nipple (39) with a valve (40).

Description

The invention refers to installations for obtaining biomethane in the composition of biogas and can be used in different branches of agriculture and the processing industry.

Biogas represents a renewable source of energy, and its objective is to intensify the process of obtaining biomethane by implementing some constructive features and by introducing into it some biologically active additives to increase the production of biomethane, increase the degree of purification and reduce the cost. The invention includes a complex technical, technological and biochemical process for obtaining biogas, using as raw material agricultural and processing industry waste, such as alcohol or divine borhot. In this sense, the proposed invention can be applied for the treatment of high-load wastewater of agro-industrial enterprises to obtain biogas and, based on it, electricity and thermal energy, of stabilized sludge, which can serve as fertilizers or vitamin supplements for animal feed , ensuring at the same time environmental protection and sustainable socio-economic development.

An anaerobic bioreactor for the decontamination of hard-to-biodegradable organic compounds is known, which contains a body, inlet and outlet pipes for the treated liquid, a solid support for fixing the microflora and a layer of granular microflora, as well as sludge and biogas outlet pipes, a hydrolyzer and a rotating electromagnetic field generator [1].

This bioreactor does not provide sufficient process capacity and major biomethane production for use.

The technical problem that the invention solves is to increase biomethane production and its degree of purification, ensure the efficiency of the process in continuous flow and reduce material and operating expenses.

The combined anaerobic reactor for obtaining biomethane removes the disadvantages mentioned above in that it consists of a bioreactor with a cylindrical body with a conical bottom, joined with a sludge discharge nozzle. In the bioreactor there is a charge for fixing the microflora and a level indicator. A reservoir is installed in the upper part of the bioreactor, equipped with a level indicator, and a float valve is placed at the transition from the reservoir to the body. An electromagnetic stirrer is placed on the tank, which contains metal particles of a soft magnetic material, a rotating electromagnetic field generator, connected to a three-phase current variator, a nozzle for supplying liquid to be treated and a valve for its discharge into the tank . A receiver is installed in the lower part of the bioreactor, which is equipped with an automatic level indicator, connected to a control block, coupled with a pump, equipped with a methane-liquid ejector, which, by means of a biomethane suction pipe , communicates with the upper part of the bioreactor. The ejector is connected to a sprayer and a vacuum cleaner, located at the bottom of the body. In the lower part of the receiver is connected a spigot with a regulation valve and a recirculation pipe, connected to a pump, which is coupled to the control block and connected to a liquid ejector, connected to an electrogenerator with a hydrogen diaphragm and a perforated distributor, located above the vacuum cleaner. A hose is mounted in the upper part of the receiver, connected by a siphon to an absorption chamber, filled with activated carbon for the purification of biomethane from sulphurous compounds, connected to the body and equipped with a vibration actuation device and a discharge nozzle methane with a valve.

The technical result of the invention consists in the following.

When supplying alternating current to the generator, which can be a standard electric motor stator, a rotating electromagnetic field is formed, under the action of which metallic particles, cylindrical or otherwise, made of a soft magnetic material, such as steel containing little carbon, which is inside the magnetic body of the electromagnetic stirrer and the amount of which varies between 2.6 and 5.5% vol., start to rotate chaotically and collide, forming a fluidized magnetic layer. The optimal ratio between the length of these particles and their diameter (l/d), for the diameter of 1.5 mm, is within 5...6. At the same time, according to the known data, the particles rotate around their axes with a variable angular velocity, moving chaotically in the volume of the layer with an angular velocity (φ), which has the average probable values:

φ = 0.415·102B-0.45(l/d)- 0.52d-0.28C-0.25[l(R-r)] 0.03.

Apart from this, there is a circular translational rotation of the entire global layer in the direction of the rotation of the field with the most probable values of the speed of the translational movement (ω):

ω = 0.327·10-2B0.82(l/d)- 0.13d-0.28C0.25[l/(R-r)]- 0.83,

where 1/d is the parametric similarity criterion (l - length, d - particle diameter);

B - electromagnetic field intensity, T1;

R-r = ΔR - the distance between the electrodes;

C - concentration of particles in the volume of the electromagnetic stirrer.

Such a character of the chaotic movement of metal particles and the collisions between them leads to the fact that solid mechanical particles, such as large particles of wheat or corn groats, contained in the borhot from the production of alcohol and representing cellulose, are subjected to mechanical action and intensive magnetohydrodynamics, as a result of which not only their shredding takes place, but also their homogenization through the partial disaggregation of the intermolecular bonds until they become gelatinous or soluble in water.

The action of the magnetic field also contributes to this, which facilitates the breaking of the polymer bonds of the macromolecular compounds and the increase of the organic mass acceptable as food for the microflora in the biochemical processes of anaerobic fermentation, as well as, respectively, the increase in biomethane production.

At the same time, the possibility of uniform mixing of stimulating biologically active microorganisms, specially introduced into the treated liquid, such as compounds of the triterpene series, whose action accelerates the development of anaerobic fermentation processes, which increases biogas production, is ensured.

The vacuum conditions of the bioreactor with the help of the ejector system ensure the discharge of biogas in a continuous flow, contribute to increasing its production, because without it the microbubbles of released gases (CH4, CO2, etc.) are adsorbed by microorganisms, which leads to the inhibition of the development biochemical process.

The ejection is ensured by the operation of the pump that evacuates part of the treated liquid in the lower part of the bioreactor, sucking the biogas with the formation of a gas-liquid phase. At the same time, conditions are created, thanks to which the carbon dioxide contained in the biogas, whose solubility in the aquatic environment is higher than that of methane, dissolves in the receiver. After spraying the gas-liquid phase, biomethane is released in a more concentrated form and, subsequently, it is directed to the advanced purification, and CO2 saturates the liquid phase and is discharged into the lower part of the receiver, where its quantity is controlled with the help of an indicator automatic level.

As soon as the preset level of liquid in the receiver vessel is reached, the signal of which is transmitted to the control block, which, in turn, starts the recirculation pump and the gas-liquid ejector pulls the electrolysis hydrogen from the hydrogen diaphragm electrogenerator. During this time, H2 mixes with CO2 contained in the liquid, which enters the methanogenic process again. Thus, the recirculation of the treated liquid intensifies the mass exchange and transport process in the bioreactor that contains a load for fixing the microflora and, at the same time, leads to the biochemical interaction of both gases under methanogenic conditions and their transformation into the form of biomethane according to the general reaction: CO2+4H2→ CH4+2H2O.

Hydrogen from the biogas composition, like CO2, is released during the acetogenic phase of the biochemical process of anaerobic fermentation. But the cause of the high amount of CO2 in the composition of biogas, which is formed under standard conditions of anaerobic fermentation of liquid organic waste, is the insufficient amount of H2, therefore the additional introduction of electrolyzed hydrogen ensures a balanced ratio of gases, close to the stoichiometric one, and an increased production of biomethane in the summary biochemical process.

The intensification of mass exchange processes in the bioreactor favors the amplification of the action of biologically active microadditions and the development of the synergistic effect of the triterpenic chemical structure, for example, which leads to the increase in the capacity of the biochemical process of anaerobic fermentation of organic liquid waste and the increase of biomethane production to maximum values.

The biogas admitted from the receiver also contains a series of impurities, the most aggressive of which are sulfur compounds, which undergo advanced purification in an absorption chamber filled with activated carbon as a catalyst for redox processes. Thanks to it, hydrogen sulfide, sulfur, carbon or mercaptans are oxidized by oxygen to elemental sulfur according to the reactions:

2H2S+O2=2H2O+2S+Q,

CS2+O2=CO2+2S+Q.

The reaction is accelerated in the presence of ammonia in concentrations up to 0.39 g/m3, which is normally always contained in biogas in small quantities. The optimal temperature for this process is 20...40°C. In connection with the high caloric effect, these reactions take place with a high intensity of the process.

At the accumulation of approx. 100% sulfur from the mass of carbon, the redox reactions are stopped and the activated carbon is regenerated. Sulfur is extracted from spent carbon with ammonium sulfide solution:

(NH4)2S+nS= (NH4)2Sn+1 .

Ammonium polysulfide is then decomposed on heating with release of elemental sulphur:

(NH4)2Sn+1=2NH3+H2S+nS1,

which is a good quality commercial product.

The activated carbon is loaded into the absorption chamber in layers: the first bottom layer has large particle sizes (approx. 10 mm), then the layer with sizes of 2...4 mm and, finally, the upper layer of 1... 2 mm. The required degree of purification is obtained at a biogas velocity of up to 80 mm/s.

Thanks to the regeneration, the activated carbon can be used in the long term, during two and more years.

The invention is explained by the drawing in the figure, in which the scheme of the combined anaerobic reactor for obtaining biomethane is represented.

The combined anaerobic reactor for the production of biomethane consists of the bioreactor 2 with the cylindrical body 1 with a conical bottom, connected to the sludge outlet 3, the charge 4 for fixing the microflora, the level indicators 5 and 6 for registration, the device 7, composed of the float 8 and the valve 9, the tank 10, the electromagnetic stirrer 11 with the nozzle 12 for supplying the liquid to be treated and the valve 13 for its discharge into the tank 10. Inside the electromagnetic stirrer 11 are placed the metal particles 14 of a soft material, and outside - the generator 15 rotating electromagnetic field, connected to the variator 16 of three-phase current. In the lower part of the bioreactor 2, the receiver 17 is installed, which is equipped with the automatic level indicator 18, connected to the control block 19, coupled with the pump 20, equipped with the methane-liquid ejector 21, which, through the suction pipe 24, of biomethane, communicates with the upper part of the bioreactor 2, at the same time the ejector 21 is connected to the sprayer 25 and the vacuum cleaner 23 through the pipe 22. In the lower part of the receiver 17 is connected the nozzle 26 with the regulation valve 27 and the recirculation pipe 28, connected to the pump 29, which is coupled to the control block 19 and connected to the liquid ejector 30, connected to the electrogenerator 31 with hydrogen diaphragm, which is equipped with the retaining flap 32 and the perforated distributor 33, located above the vacuum cleaner 23. In the upper part of the receiver 17 is fitted with the hose 34, connected through the siphon 35 with the absorption chamber 36, filled with activated carbon 37 for the purification of biomethane from sulphurous compounds, connected to the body 1 and equipped with the actuator 38 with vibration and the nozzle 39 for discharging methane with valve 40.

Any of the known constructions can be used as a hydrogen diaphragm electrogenerator, but the best of these is the diaphragm electroreactor, equipped with flat or porous electrodes in continuous flow, with the surface modified with Ni-Re, Ni-W or Ni-Mo, which has low hydrogen release overvoltage and low power consumption. They can be supplied with electricity from the cogeneration plants, which operate with biogas within the purification plants.

The combined anaerobic reactor for obtaining biomethane works in the following way.

Before the start of operation and for the operation of the reagent, microquantities of natural biologically active additions from the group of triterpene compounds of the methanogenesis process are introduced into the liquid waste, such as alcohol and divine borth, through the nozzle 12 in the electromagnetic stirrer 11 and the source is connected to alternating current from the variator 16 to the generator 15 and, following the appearance of the rotating electromagnetic field, the metal particles 14 begin an intense chaotic rotation, agitating the liquid with additions and homogenizing the mechanical particles 14 contained in it. Then the valve 13 is opened and the homogenized mixture passes into the tank 10 and, through the device 7 with open float 8 and the valve 9, it is poured into the bioreactor 2, which is previously filled with the charge 4 for fixing the microflora. In order to initiate the methanogenic fermentation, active microflora can be introduced from the analogous installations of the anaerobic bioreactors in operation together with the treated liquid. From the moment of reaching the predetermined level of liquid in bioreactor 2, indicated by level indicator 5, the float 8 with valve 9 rises to the surface and closes the liquid overflow from tank 10, and in bioreactor 2 the methane fermentation process takes place.

After that, the pump 20 is put into operation and the liquid to be treated passes through the aspirator 23, the pipe 22 and the ejector 21, creating a vacuum, thanks to which the biogas is sucked into it with the formation of a gas-liquid mixture, which is pumped under pressure into the sprayer 25, mounted in the receiver 17, filling it to the set level, which is controlled by the automatic level indicator 18.

The vacuuming of the gas cushion, carried out by the ejector 21 above the surface of the liquid to be treated in the bioreactor 2, amplifies the release of gas from it, which reduces the possibility of inhibiting the activity of microorganisms by biogas and intensifies it, leading to an increase in the overall efficiency of the release process biogas.

During the spraying of the gas-liquid mixture, the poorly soluble methane and other gaseous components accumulate in the upper area of the receiver 17 and, through the hose 34 and siphon 35, are evacuated into the absorption chamber 36, filled with the activated carbon 37, where it is purified from aggressive compounds containing sulphides and is removed through the nozzle 39 with the valve 40 open to be used later. In order to avoid agglutination of the activated carbon 37 and to reduce the hydraulic resistance of the gas flow, the vibration actuator 38 can be periodically or permanently connected to fluidize the carbon filling.

Simultaneously with this process, the liquid subjected to treatment and saturated with carbon dioxide (CO2), which accumulates in the lower part of the receiver 17, at the signal of the automatic level indicator 18, through the control block 19, engages the pump 29, which through the pipe recirculation valve 28 sucks the liquid into the liquid ejector 30, where due to the vacuum effect, through the check valve 32, it sucks the hydrogen generated in the electrogenerator 31 with hydrogen diaphragm and saturates the liquid with it, which is then discharged through the perforated distributor 33 back into bioreactor 2, ensuring the recirculation regime. Due to the fact that the fermentation gas phase contains up to 30% by volume of CO2, which has a superior solubility in water, it remains partially in the composition of the liquid enriched with it. That is why, in the methanogenic biochemical process, CO2 and other intermediate products of fermentation react with the introduced hydrogen, thus contributing to the increase of the methane production efficiency and, in general, of the biomethane content in the biogas composition.

The recirculation of the liquid subjected to treatment with the help of the pump 29 through the pipe 28, the ejector 30 and the perforated distributor 33 from the receiver 17 in the bioreactor 2, leads to the disturbance of its content, thereby contributing to the creation of favorable exchange conditions and mass transfer, amplifying its degassing and the rise of CH4 and CO2 gas bubbles absorbed on the surface, which leads to the intensification of the development of the activity of microorganisms. An important role in the methanogenic process is attributed to the stimulating influence of microadditions of biologically active substances in the composition of the liquid undergoing treatment, which play a double role: they accelerate the productivity of the methanogenesis process and serve as an additional factor in increasing the production of biomethane in the composition of biogas.

The continuity of the biochemical process of methanogenic fermentation of liquid organic waste is ensured by regulating the evacuation of a part of the treated liquid through the nozzle 26 and the valve 27, and the sludge formed in the bioreactor 2 is periodically evacuated through the nozzle 3, also due to the presence of the device 7 with float 8 placed between the reservoir 10 and the bioreactor 2, which ensures the automatic introduction in continuous flow into the bioreactor of a quantity of liquid subject to treatment. Maintaining the preset level of the liquid in the receiver 17 is ensured automatically with the help of the automatic level indicator 18 and the control block 19, which signals the switching on and off of the pumps 20 and 29.

In this way, the proposed objectives of increasing the production of biomethane and the necessary degree of its purification, ensuring the efficiency of the process in continuous flow conditions, reducing the material and operating expenses, respectively, making the process cheaper, are achieved. Through complex action on the process of anaerobic fermentation of organic liquid waste provided in the proposed combined anaerobic bioreactor, the reduction of production areas and capital investments is ensured due to the increase in the productivity of biochemical processes, the biomethane content can reach values of up to 94...97% vol. , which is similar to natural gas and has a higher calorific capacity when used.

1. MD 3062 G2 2006.05.31

Claims (1)

Combined anaerobic reactor for the production of biomethane, which consists of a bioreactor (2) with a cylindrical body (1) with a conical bottom, connected to a nozzle (3) for sludge discharge; in the bioreactor (2) is placed a load (4) for fixing the microflora and a level indicator (5); in the upper part of the bioreactor (2) a tank (10) is installed, equipped with a level indicator (6), and at the transition from the tank (10) to the body (1) a valve (9) with a float (8) is placed ); an electromagnetic stirrer (11) is placed on the tank (10), which contains metal particles (14) of a soft magnetic material, a rotating electromagnetic field generator (15), connected to a three-phase current variator (16), a nozzle (12) for supplying liquid to be treated and a valve (13) for discharging it into the tank (10); in the lower part of the bioreactor (2) a receiver (17) is installed, which is equipped with an automatic level indicator (18), connected to a control block (19), coupled with a pump (20), equipped with a liquid methane ejector (21), which, by means of a biomethane suction pipe (24), communicates with the upper part of the bioreactor (2), at the same time, the ejector (21) is connected to a sprayer (25) and a vacuum cleaner ( 23), located at the bottom of the body (1); in the lower part of the receiver (17) a nozzle (26) is connected with a regulation valve (27) and a recirculation pipe (28), connected to a pump (29), which is connected to the control block (19) and united with a liquid ejector (30), united with an electrogenerator (31) with a hydrogen diaphragm and a perforated distributor (33), located above the vacuum cleaner (23); in the upper part of the receiver (17) a hose (34) is mounted, connected by a siphon (35) to an absorption chamber (36), filled with activated carbon (37) for the purification of biomethane from sulphurous compounds, connected to the body (1) and equipped with an actuator (38) with vibration and a methane outlet nozzle (39) with a valve (40).