RU2456247C2 - Methane tank - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to environmental protection and serves to process organic substrates with relative moisture content of 90-98%, i.e. unpadded manure, excrements of agricultural animals, sediments and silt, and industrial and household effluents. Methane tank for anaerobic treatment of organic substrates consists of tight case with initial substrate feed branch pipes and treated substrate discharge branch pipes, biogas discharge branch pipe, and central tube. Tube top and bottom are exposed with respect to methane tank inside. Biogas feed branch pipe is arranged coaxially inside central tube bottom and communicated compressor with biogas discharge branch pipe. Methane tank incorporates vertical immobilisers of anaerobic micro flora arranged between central tube and methane tank case and made up of set of vertical rods with porous structure and combined by stiff frame-type suspension coupled via shaft with the drive.

EFFECT: optimised homogenisation and heating, developed interphase mass exchange.

3 cl, 2 dwg

Description

The proposed device relates to the field of environmental and energy-generating equipment and is intended for the processing of organic substrates with a relative humidity of 90-98%: litter, manure, farm animals, sludge and sludge as waste from the processes of mechanical and biological treatment of domestic and industrial waste water waters of the agro-industrial complex. Methantenk can be used in small enterprises for the processing of agricultural products, farmsteads (farms), recreational service enterprises (holiday homes, tourist complexes).

In general, any organ-containing biodegradable substrate with an organic matter content of at least 50% of the amount of the solid phase and not containing substances that cannot be eliminated by available methods that inhibit anaerobic processes in the digester can be the raw material for the digester.

Methantenk can be used as the main apparatus of a bioenergy plant or as a basic apparatus module in the formation of technological lines for anaerobic processing (treatment) of organic waste and wastewater.

A device of this purpose is known, the description of which is presented in UK patent Application No. 2162195, Jnt. cl. C02F 3/28, 07/19/1985 "Jmproved anaerobic fermentation method and apparatus", applicant "Bisan Holdings Pty ltd."

The device is a digester, made in the form of a sealed structure of a vertical type with a cylindrical-conical shape of the body, equipped with nozzles for supplying the initial substrate, removal of the spent substrate, a pipe for biogas removal. Mixing the contents of the digester is carried out by means of a bubbler device located under the lower part of the central pipe. The wall of the central pipe is hollow and equipped with nozzles for supplying and discharging the coolant. The bubbler device contains a pipe for outputting biogas into the working space of the digester under the central pipe and is connected to a compressor for supplying biogas under pressure. The introduction of biogas into the space of the central pipe, which is small in comparison with the working volume of the digester, causes a sharp drop in the biomass density (up to 500 kg / m ³ ) due to an increase in the fraction of the gas phase and thereby leads to the emergence of a lifting force acting along the vertical axis of the central pipe.

The resulting biomass circulation according to the scheme “central tube - annular working space of the digester” leads to rather intensive mixing of the digester contents and, ultimately, to intensification of mass transfer and biochemical processes. Thanks to the hollow design of the wall of the circulation pipe, it becomes possible to combine the mixing and heating of biomass in the digester. The coolant is supplied to the hollow wall of the circulation pipe from an external biogas-powered heat generator. In addition to the annular space formed by the circulation tube and the inner wall of the digester, there is an outer annular space in which the means for immobilizing anaerobic microflora are placed to process the predominantly liquid phase of the digester contents. Excess anaerobic sludge from the lower part of the methane tank with immobilized microflora is discharged into the main working space of the methane tank. The porous material for immobilizing anaerobic microflora is oriented in the outer annular space in such a way as to provide upward movement of the stream to be treated. This technical solution allows to simplify the design and increase the reliability of the digester by placing means of heating and mixing biomass inside the apparatus. The presence of immobilization means allows to increase the concentration of active biomass in the working space of the apparatus and thereby increase the depth of processing of the substrate into biogas while increasing the relative methane content in biogas.

The main disadvantage of the digester according to UK patent No. 2162195 is the impossibility of involving substrates with low humidity in the processing using immobilized anaerobic microflora. According to patent No. 2162195, concentrated substrates are processed in a separate chamber with a central pipe, and an external annular chamber with immobilization means is used to process flows with a low solids content. As a result, the scope of the digester is narrowed and the overall dimensions increase (worsen). Another disadvantage is the insufficiently high intensity of mass and heat transfer in the annular space around the central pipe. If the linear velocities of the two-phase flow inside the circulating central pipe reach 0.5 m / s or more, then in the annular space, the cross-sectional area of which is many times greater than the same value for the central pipe, while maintaining the circulating flow rate, the flow velocity decreases many times. As a result, the heat exchange between the outer surface of the hollow wall of the central pipe and the biomass decreases sharply. A decrease in the velocity of the flow also leads to a decrease in the intensity of biochemical reactions in this area, a decrease in the rates of supply and removal of metabolic products, primarily gaseous ones.

The result of the above technical shortcomings is the deterioration of the digesters, primarily the specific yield and composition of biogas, the reduction in the quality of processing of the initial substrate, expressed as an increase in the passage through the digester of untreated, i.e. not stabilized and non-disinfected particles of the substrate, narrowing the scope of the digester.

A device is known according to Japanese patent No. 4092765 B2, Jnt. cl. C02F 3/02, 03.1998, patent holder “Kurita Water Ind. Ltd ”, according to which these shortcomings were largely eliminated by introducing a suspended porous biomass carrier into the working space of the apparatus in combination with mixing of the multiphase system“ substrate - immobilized biomass - suspended biomass - gas phase ”. Mixing is carried out by means of a paddle mixer, the working bodies of which completely cover the reaction space of the apparatus. As a result, mass transfer at the interface is significantly intensified, the depth and intensity of processing of the substrate increases, and processing of substrates with reduced humidity becomes possible.

The disadvantages of this device are:

- lack of internal heat transfer means;

- the inability to maintain the minimum necessary intensity of the process in the absence of mixing;

- significant energy consumption for mixing due to the large frontal resistance of the vertical blades, overlapping the living section of the apparatus in a vertical plane;

- the need to organize the process of recycling immobilizing material in the process of unloading the apparatus;

- the uncertainty of the solution to the problem of sealing the mixer shaft under anaerobic conditions.

As a result, the reliability of the operation of the device decreases, the specific energy consumption for processing the substrate increases.

Closest to the claimed technical solution is the device "Metentenk for anaerobic treatment of organic waste", cl. C05F 3/00, VIESH application No. 2009 109765, priority dated 19.03.2009.

The main disadvantages of analog devices are eliminated by organizing the biochemical processing of the substrate in two main zones of the digester - inside the central pipe with a hollow wall, pipes for supplying and removing coolant, and a pipe for supplying biogas. Vertically oriented means of immobilization of anaerobic microflora are placed in the annular space between the central tube and the cylindrical wall of the digester and are made in the form of a set of vertical rods with a porous structure with the possibility of reverse rotation of the whole set. The upper part of the set of vertical rods is combined by means of a rigid frame suspension. The upper part of the digester is equipped with an annular hydraulic lock and an electromechanical drive connected through a rigid shaft with a rigid frame suspension. The rigid shaft is hermetically connected to the immersion cap of the annular hydraulic lock. Alignment of the temperature field inside the digester tank is carried out by the presence of heating jackets on the digester wall and the central pipe. The coolant between the hollow wall of the central pipe and the jacket is distributed by means of a three-way valve depending on the temperature conditions in the central and wall parts of the digester tank.

The result of this technical solution is a rational combination of two basic processes of anaerobic processing of organic substrates of different humidity: intensive mixing (homogenization) and heating of the substrate inside the central pipe and developed interfacial mass transfer in the system of “attached microflora - substrate” in the annular space. Since the main part of the biomass is in the attached state and is located in the annular space, the intense effect inside the central tube necessary for averaging, hydrolysis, and degassing of the substrate does not negatively affect the metabolism process. The creation of two mutually complementary zones of processing the substrate in combination, uniform heating of the working space of the digester, together, can increase the reliability of the device, increase the depth and intensity of anaerobic processing of the substrate. The modular principle of the formation of means of immobilization of anaerobic microflora in combination with the possibility of reverse rotation of the entire immobilizing assembly allows effective control of the processing of the substrate at the design and operation stages. In case of failure of the drive of the immobilizing assembly, failure of the pipe for supplying biogas to the cavity of the central pipe, the device largely maintains its operability. The use of vertical rods with a round or oval cross-section and an annular water seal can significantly reduce the specific energy consumption for the process.

The main disadvantage of the prototype device is the difficulty of maintaining gas tight conditions in the input node of the frame suspension shaft by means of an annular hydraulic lock due to the evaporation of the locking fluid, as well as the need for internal intermediate supports for the rigid shaft. The presence of an electromechanical drive (gear motor) in the upper part of the digester complicates its design, increases the overall dimensions of the apparatus, and complicates its operation in open areas.

The objective of the invention is to reduce the cost of the manufacture and operation of the digester, increasing the reliability of operation in a wide range of operating conditions while maintaining the above advantages - high intensity and depth of anaerobic processing of organic substrates with a high degree of factory readiness and wide scope of the device.

The technical result of the invention is the elimination of structurally difficult and in operation nodes, the unification of energy sources for the intensification of processes in the main processing zones of the substrate.

The technical result is achieved by the fact that the proposed digester consists of a sealed housing with nozzles for supplying the initial substrate and removal of processed substrates, a nozzle for biogas removal, contains a central pipe, the upper and lower parts of the pipe are open with respect to the working space of the digester, coaxially placed inside the lower part of the central pipe a biogas supply pipe connected through a compressor to a biogas removal pipe is equipped with vertically oriented means of immobilization of an anaerobic mic flora, which are placed in the annular space, between the central tube and the digester tank, and made in the form of a set of vertical rods with a porous structure with the possibility of reverse rotation of the entire set and combined in the upper part by means of a rigid frame suspension connected to the drive through the shaft, the drive is made in in the form of a vane air motor, the casing of which is rigidly fixed inside the upper part of the casing of the digester, and the inlet and outlet nozzles of the vane air motor through a reversing gasor the distributor is connected to the biogas supply pipe and the compressor discharge path. Between the reversible gas distributor and the biogas supply pipe, a sequentially placed adjustable throttle and a gas ejector are provided, the nozzle of which is connected through the first controlled gas valve to the compressor discharge path and the pressure part is connected to the biogas supply pipe through the first pressure regulator. The reversible gas distributor is connected to the compressor discharge path through a second controlled gas valve and a second pressure regulator placed in series.

The essence of the invention is illustrated by figure 1, which shows a structural diagram of a digester with a compression system and controlled distribution of biogas.

The digester 1 contains a sealed housing 2 with nozzles for supplying and discharging the starting and processed organic substrates and a nozzle for biogas removal 3. The digester 1 also contains a central pipe 4 with a hollow wall 5, equipped with nozzles for supplying and discharging a heat carrier. In the lower part of the pipe 4, a pipe 6 is coaxially placed for supplying compressed biogas. The upper and lower parts of the central pipe 4 are open with respect to the working space of the digester 1. In the annular space formed by the cylindrical part of the housing 2 digester 1 and the central tube 4, vertical rods 7 with a porous structure are placed. The entire set of vertical rods 7 in the upper part is connected as a whole (assembly) by means of a rigid frame suspension 8 and has the ability to reverse rotation around a vertical axis. The frame suspension 8 by means of a rigid shaft 9 is connected with a bladed air motor 10 located in the upper inner part 11 of the digester 1. Wall of the housing 2 of the digester 1 can be equipped with a jacket with pipes for supplying and discharging the coolant. To reduce heat loss to the environment, thermal insulation 12 is provided.

The sampling tank 1 and biogas are compressed by a compressor 13 with an electric or gas engine 14. The suction part of the compressor 13 is connected to the biogas exhaust pipe 3 through the biogas preparation unit 15. The compressor discharge path 13 is connected to the receiver 16, which is connected through distribution pipelines 17, 18 and 19 is associated with a safety valve 20, a gas filter 21, and a gas engine 22 of a cogeneration unit, respectively.

The inlet 23 and outlet 24 nozzles of a rotary air motor 10 through a reversible gas distributor 25 are connected through an adjustable throttle 26, a gas ejector 27 and a first pressure regulator 28 with a nozzle for supplying biogas 6, and through a second controlled valve 29 and a second pressure regulator 30, a gas filter 21 and the distribution pipe 18 - with the discharge path of the compressor 13. The nozzle 31 of the gas ejector 27 through the first controlled valve 32, the gas filter 21 and the distribution pipe 18 is also connected to the discharge path of the compressor row 13. Reversing the gas distributor 25, the first control valve 32, the second control valve 29 via an electrical control channel associated with the program-time setter 33.

The rotary air motor 10 is equipped with a rigid shaft on which the blade 34 is mounted with the possibility of reversible angular movement within at least 300 ° between the stops 35 and 36. The reversible valve 25 can be provided of any known type, figure 2 shows a reversible valve of the spool type, consisting of a housing 37, a two-way spool mechanism, consisting of pistons 39, 40 connected by a rod 38, a biogas supply pipe 41, biogas removal and supply pipes 42 and 43, under for prison to "conditionally" inlet 24 and the outlet nozzles 23 of the vane air motor 10, exhaust pipes 44 and 45 which via an adjustable throttle 26 are connected to the gas ejector 27.

All elements of compression and regulated distribution of biogas are standard, of mass use and are highly reliable.

The proposed device operates as follows.

The initial substrate enters the body 2 of the digester 1 and interacts with suspended and immobilized anaerobic microflora. The substrate in the course of sequentially carried out enzymatic biochemical reactions is converted into processed products - stabilized and disinfected biomass - effluent, and biogas. Processing of the initial substrate inside the digester 1 is carried out under conditions of anaerobiosis, dosed supply of the initial substrate, mixing the contents of the digester, maintaining the temperature of the contents of the digester at an optimal level at which the maximum intensity of the processing process is achieved.

Strict anaerobiosis is ensured by the hermetic design of the digester 1.

The metered feed of the initial waste (substrate) is provided by typical means of a digester 1 - a unit of preliminary processing of the substrate, which includes a pump, a system of pipelines and shut-off and control equipment, dosing containers and other necessary equipment.

Mixing the contents of the digester 1 is achieved by the fact that after entering the initial substrate, the received portion (dose), as well as the recirculated biomass from the annular space between the housing 2, digester 1 and the central pipe 4 are involved in the lower open part of the central pipe 4. An inducing cause causing the flow to flow inside circulation pipe 4, is a sharp drop in flux density when biogas is introduced into the liquid medium through the pipe 6. In the process of rising gas bubbles, in addition to the axial movement of the entire two-phase of the second stream, intensive mixing (homogenization) of the newly received portion of the waste and recirculated biomass is carried out. In this case, intensive degassing of the biomass occurs, which leads to an improvement in the processing conditions of the substrate at subsequent stages. A partial drop in the biomass temperature caused by the arrival of another portion of organic waste is compensated by the supply of thermal energy from the coolant supplied to the hollow wall 5 of the central pipe 6. Thus, by means of a central pipe 4 equipped with a biogas sparging device - pipe 6 and hollow wall 5 - heat exchanger , the contents of the digester 1 and the initial substrate are axially moved from the lower part of the casing to the upper, mixing of the substrate and recirculated biomass, maintaining temperature in the central part of the device at an optimal level.

After diverting part of the biogas and part of the treated substrate from the stream, the rest of the stream enters the annular space formed by the body 2 of the digester 1 and the central pipe 4. Further anaerobic treatment of organic waste is carried out in the annular space, and the treatment is carried out under conditions of active contact of the substrate with immobilized microflora. The substrate entering the annular space makes a complex motion, consisting of axial mixing due to the lifting force of the central pipe 4, and rotational (circular) movement arising due to the forced rotation of the assembly (assembly) of vertical rods 7 placed on the frame suspension 8. As a result, the individual particles of the substrate and attached anaerobic microflora are in a fairly intense interaction.

The surface of the interphase exchange is constantly updated, there is an intensive release of the main metabolic product - biogas into the gas space of the digester 1. Rotation of the assembly of vertical rods 7 provides a constant supply of substrate and removal of metabolic products from the contact zone.

A positive effect of the rotation of the assembly of vertical rods 7 is the intensification of heat transfer between the biomass and the coolant circulating in the hollow wall 5 of the central pipe 4.

The assembly of the vertical rods 7 is rotated by means of a vane air motor 10 through a rigid shaft on which a vane 34 of the air motor 10 is fixed, which receives the pressure of biogas supplied from the receiver 16 through a gas filter through a second controlled valve 29 and a second pressure regulator 30 with the possibility of reversible rotation. Reversible rotation is carried out by means of a reversible gas distributor 25. According to figure 2, biogas under pressure through a second pressure regulator 30 and a second controlled valve 29 through a nozzle 41 enters the internal cavity of the spool of a reversible gas distributor 25 formed by pistons 39 and 40. Next, the biogas passes through a nozzle 43 of the gas distributor 25 and the pipe 23 into the cavity of the blade air motor 10, acting on the blade 34 and through the shaft 9 transmitting rotation to the vertical rods 7. At the same time, e the vivalent amount of biogas through the nozzles 24, 42 into the exhaust pipe 44 and then through an adjustable throttle 26 into the gas ejector 27. When the slide valve is moved to the right, the biogas is supplied through the nozzles 41, 42, 24, and the blade 34 moves backward. The blade moves 34, and therefore, the vertical rods 7 are regulated by a second controlled valve and an adjustable throttle 26.

Part of the biogas from the receiver 16 is fed through the first controlled gas valve to the nozzle 31 of the gas ejector 27, which also receives part of the spent biogas from the vane air motor 10. Thus, the gas ejector 27 works as a jet compressor, and the energy spent in the vane air motor 10 of the biogas is used additionally, increasing the pressure in the pipe 6 for supplying compressed biogas to the Central pipe 4.

The structure of the reverse, as well as the on-off mode of the vane air motor 10 and biogas supply to the pipe 6 are regulated by means of a program-time adjuster 33.

The gaseous metabolic product - biogas is discharged from the upper inner part 11 of the digester 1 through the biogas outlet pipe 3. The extraction from the digester 1 of the biogas is carried out by the compressor 13 through the biogas preparation unit 15, in which the biogas is drained and normalized. Next, the compressor 13 biogas enters the receiver 16, from which through the distribution pipes 18 and 19 is fed into the vane air motor 10 and the gas engine 22 of the cogeneration unit, respectively, the safety valve 20, the gas filter 21 and the gas engine 22 of the cogeneration unit, respectively. Thus, part of the biogas is used for the proprietary needs of the digester (intensification of mass transfer, regulation of the thermal regime), the remaining part of thermal and electric energy (up to 78%) is marketable.

Claims (3)

1. A digester, consisting of a sealed enclosure with nozzles for supplying the initial substrate and removal of the processed substrates, a nozzle for biogas removal, a central pipe, the upper and lower parts of the pipe are open with respect to the working space of the digester, a nozzle for supplying biogas is coaxially placed inside the central pipe, connected through a compressor to a branch pipe for biogas removal, vertically oriented means of immobilization of anaerobic microflora, which are placed in the annular space between the central pipe and a digester body and are made in the form of a set of vertical rods with a porous structure with the possibility of reverse rotation of the entire aggregate and combined in the upper part by means of a rigid frame suspension connected to the drive through a shaft, characterized in that the drive is made in the form of a blade air motor, the body of which is rigidly fixed inside the upper part of the digester tank, and the inlet and outlet nozzles of a blade air motor through a reversible gas distributor are connected to a nozzle for supplying biogas and discharge path of the compressor. 2. The digester according to claim 1, characterized in that between the reversible gas distributor and the nozzle for biogas supply, an adjustable throttle and a gas ejector are provided in series, the nozzle of which is connected through the first controlled gas valve to the compressor discharge path and the pressure part is connected to the nozzle for supply biogas through the first pressure regulator. 3. A digester according to any one of claims 1 and 2, characterized in that the reversible gas distributor is connected to the compressor discharge path through a second controllable gas valve and a second pressure regulator arranged in series.

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