RU2539100C1 - Biogas unit - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: biogas unit contains heat insulated methane tank, consisting of an extruder mixer, electric biomass mixers, pumps, chambers of hydrolytic, acid and methane fermentation, each is fitted with a heat exchanger. To the outlet of the methane tank, to the methane fermentation chamber the gas-holder and the fermented mass separator are connected. The biogas unit is fitted with the unit of sources of renewable and other currently excessive energies in networks. The unit of sources of renewable and other excessive energies comprises the thermal accumulator fitted with heat exchangers, fire-bar elements and a generator; this thermal accumulator is connected to sources of renewable energy and mains. Meanwhile the heat accumulator inlet for make-up water is connected to the line, and hot water outlets of the heataccumulator are connected to an extruder mixer and fermentation chambers. Heat accumulator's fire-bar element by means of electric energy switches is connected to electric mixers, pumps and the extruder mixer or to the generator with a possibility of operation of the latter from the sources of renewable energy or in case of their absence - from the mains during the time period of low tariffs for payment of the electric power.

EFFECT: increase in biogas production due to providing the optimum modes of continuous fermentation of biomass in zones of cold climate with the long heating period.

4 cl, 1 dwg

Description

The present invention relates to bioenergy and is intended to increase the efficiency of the fermentation units in the digesters and biogas plants (BSU).

Existing biogas plants spend a significant part of the biogas they produce to maintain the required temperature of the substrate by burning biogas in hot water boilers [1]. Often used for these purposes is external thermal or electrical energy, including from some renewable sources.

Known "Bioenergocomplex" according to the author's certificate of the USSR No. 1527191 for anaerobic digestion of biomass using solar energy [2] (analog).

The bioenergocomplex contains a reactor tank, a solar energy collector, heat exchangers, a pump, the collector made in the form of a hot box with selective glazing and located with a slope, and the heat exchangers communicated through a forced circulation pump.

The disadvantage of this device is the inability to maintain the required temperature in the reactor at night, in winter, and also in the presence of strong cloudiness, when the magnitude of solar insolation is insignificant.

Also known "Biogas plant" (analogue) according to the patent No. 2065408 of the Russian Federation, using the energy of the sun and wind [3].

This installation contains a reactor divided by a partition into two interconnected chambers, a loading hatch for biomass and a hatch for unloading the fermented mass, as well as a heat exchanger from a solar heating installation and a mixing device in the form of two rows of blades connected to a wind turbine, the heat exchanger being mounted in a vertical partition.

The disadvantage of this device is the lack of the ability to accurately maintain the fermentation temperature of biomass at any time period.

In the book “Treatment of wastewater and sediment in digesters” [4] on p.14 it is stated: “... from the moment the temperature is established, the bacterial cultures adapt to it; changing it by 3-4 ° C can lead to inhibition of methane and the resumption of acid fermentation ... ” The solar collector is not able to stably maintain the required temperature in the reactor in the absence or weak solar insolation.

Another disadvantage of this device is the use of a wind turbine directly for mixing biomass in the reactor. In the book “Fermentation Systems” [5] on p.21 it is explained: “... thus, the main task of mixing is to prevent settling of the material, destruction of the upper crust, desorption of biogas and ensuring the homogeneity of the culture fluid according to physico-chemical parameters ...”.

Wind energy is not a stable quantity. In the Russian Federation, wind flows in the summer have ranges of 0.5 ... 2 m / s, which is insufficient for the operation of wind power plants. The required mode of biomass mixing every 2 ... 3 hours for several minutes from the wind turbines will not be provided, which will lead to the formation in the reactor of a crust on the surface of the liquid and sediment at the bottom of the reactor. The “Fermenter-gas holder" [6] is also known according to the author's certificate No. 1583367 of the USSR, in which the task of reducing heat losses is partially solved.

The fermenter-gas holder contains a housing with double walls, between which there is a coolant (paraffin) with a phase transition, a heat exchanger in the form of a closed tubular coil with a horizontal upper section filled with another coolant (metal sodium), while the upper section of the heat exchanger is provided with a transparent vacuum located coaxially around it a nozzle and a lens mounted above it with a linear focus and movable brackets. The fermenter-gas holder also contains filling and drain pipes with valves, a nozzle for biogas discharge and a flat spiral membrane for periodic mixing of biomass by shaking it when the biogas pressure is released.

The disadvantage of this device is the inability for a long time to maintain a stable temperature of the fermented biomass. From the description of copyright certificate No. 1583367 it follows that the temperature of the coil section with metallic sodium can be heated from the sun by the optical system to 530 ° C. This is a consequence of overheating of liquid paraffin placed between the double walls of the casing, and, accordingly, overheating of the fermented biomass.

The effective stabilization time of the biomass temperature will be only in the melt temperature range of the entire paraffin volume until it hardens (for B5 brand paraffin, the melting temperature is _Tmelt = 46 ° C). Thus, the temperature ranges up to the melting point of a substance with a phase transition and the ranges after the complete melting of a given volume of a substance (overheating) cannot be useful in this reactor. This disadvantage is due to the fact that the working fluid (paraffin, metallic sodium) is inside the fermenter-gas holder. In addition, in this device, crust formation is not prevented, since with a weak biogas supply, the coil spring will trigger occasionally.

Also known is the "Autonomous energy supply system for agriculture from non-traditional renewable power sources" (analogue) according to the USSR author's certificate No. 1800073, using solar and wind energy [7].

This system sets the task of maximizing the supply of thermal and electric energy to consumers with the goal of "... creating comfortable working and living conditions for people in areas remote from centralized electricity, gas, water and heat supply in hard-to-reach areas" ..., including using solar and wind energy.

This autonomous system contains a thermal power station with a boiler, a steam turbine and a condenser, a solar thermal power station with solar collectors, a heat accumulator for the solar collector, a wind station, an electrochemical battery, a biogas plant with a gas distribution unit, inverters for the consumers' electrical network, pipelines, sensors and control room.

The main link in this design is the thermoelectric station (TPP), which should generate both thermal and electric energy for consumers, and provide hot water to the solar battery of the solar collector connected to the heat exchanger of the digester of the biogas plant. Biogas from this installation, which will obviously be insufficient, serves as fuel for TPPs, so the authors provide for additional TPPs for liquid or gaseous fuel.

The wind station in the system consists of two wind wheels: the first wind wheel through the gearbox works for the mixer, and the second wind wheel - for the electric generator connected through the switch and the inverter to the network.

It was already indicated above that wind energy is not a stable value and the required mode of biomass mixing by a wind mixer will not be ensured [5], since in the absence of wind the first wind wheel does not work and biomass mixing is absent, and in the absence of solar insolation for a long time the operation of a biogas plant depends from TPP. The work of the second wind wheel on the generator, as the authors point out, is provided only in the "windy days", which are extremely few in the flat territories of the country.

The main disadvantage of this system is the availability of thermal power plants, without which it is not operational. In addition, this device is difficult to implement, due to the requirements for its autonomy and the need to supply consumers (household and industrial) with thermal as well as electric energy.

In contrast to this analogue, the “Biogas plant”, proposed by the authors, solves the problem of maximum biogas production by creating optimal modes of continuous biomass fermentation. The closest technical solution (prototype) that solves this problem is the "Installation for anaerobic digestion of organic waste with biogas" according to the patent of the Russian Federation No. 2073360, applicant JSC Center "EcoRos" [8].

This installation contains digestion chambers in the digester and an energy unit connected to the gas tank through the biogas extraction line from the digester. The energy block, burning biogas, produces thermal and electrical energy. Thermal energy from the unit through the control elements and heat exchangers in the form of thermal jackets enters the digestion chamber. Water chambers of the fermentation chambers are also equipped with heaters connected to the electric power line from the power unit.

The disadvantage of the prototype, as well as the previous analogue, is the presence of an energy block (TPP) powered by biogas fuel from the digester of this installation. Thus, in the cold season, biogas will not be produced in the required volumes for the operation of the energy block (TPP) or it will be used only for own needs, i.e. only to maintain the necessary temperature conditions of the digestion chambers. This installation does not use an additional external heat accumulator with a large heat capacity, the thermal energy from which could be accumulated, including from renewable energy sources and from the excess (unused) electricity of the networks at the moment, which would allow the installation to work in the cold season .

The objective of the present invention is to remedy these disadvantages of the installation of the prototype.

The technical result of the proposed solution is to increase the efficiency of biogas plants and increase the volume of processed biomass.

Specific forms of the technical result are expressed in the following:

- an increase in the volume of biogas produced, including in the cold season, through the use of an external autonomous heat accumulator of high heat capacity, which is part of the block of renewable energy sources;

- increasing the efficiency of the BSU by saving energy by heating the heat accumulator through the use of various sources of renewable heat and electricity, including electricity at cheap night rates from networks with excess (not needed in this period) electric energy;

- an increase in the volume of processed biomass by connecting several digesters to the autonomous external heat accumulator, provided with thermal and electric energy from a block of renewable energy sources.

As a result of a search by sources of patent and scientific and technical information, the authors did not find a set of features that characterize the described “Biogas plant”.

Thus, the proposed technical solution meets the criterion of "novelty."

Based on a comparative analysis of the proposed solution with the prior art, it can be argued that between the set of distinctive features, their functions and the task achieved, the proposed technical solution does not follow explicitly from the prior art and meets the eligibility criterion of "inventive step".

The proposed technical solution can find application in the composition of any digesters of biogas plants to increase the efficiency of their work, reduce the time of fermentation and increase the volume of processed biomass.

The drawing shows a structural diagram of the proposed "Biogas plant".

The biogas plant contains a standard thermally insulated digester 1 with an extruder-mixer 2 for grinding biomass, chambers 3, 4, 5 respectively of hydrolysis, acid and methane fermentation, equipped with heat exchangers 6, 7, 8, electric mixers 9 and pumps 10. Biogas from the methane section of the digester is supplied to the gas holder 11.

A block 12 of renewable and other excess energy sources is attached to the digester; it provides thermal and electric energy to maintain optimal fermentation processes.

Depending on the presence and magnitude of wind or hydraulic energy, a wind power installation 13 or a hydraulic turbine 14 is used in operation, which, through a multi-stage multiplier 15, rotate an electric generator 16 connected to the first heating element 17 of the heat accumulator 18 with a high heat capacity in a heat-insulated casing. To increase the generated thermal energy, a vortex heat generator 19 is connected to another output of the multiplier, loaded through the valve 20 to the first heat accumulator 21 of the heat accumulator. In the presence of solar energy, a solar collector 22 is used in the work, transmitting thermal energy through the valve 23 to the second heat exchanger 24 of the heat accumulator. The second heating element 25 of the heat accumulator through the first switch 26 is connected to the electric network 27, the second switch 28 is connected by a normally closed contact to the generator, the normally open contact is connected to the network, and its switching contact is connected to the consumers in the digester: extruder-mixer, pumps, electric mixers, etc. . (Electric sensors, control panel are not shown in the drawing). Cold water from the main is fed to the inlet 29 of the heat accumulator, hot water from its outputs 30, 31, 32, 33 enters, respectively, through the valves 34, 35, 36 to the heat exchangers of the methane, acid and hydrolysis fermentation chambers, and through the valve 37 to the extruder-mixer . A separator 38 of fermented feedstock is connected to the output of the methane chamber of the methane tank, on which one the dry residue is separated, and the separated liquid is fed back to the cameras of the methane tank.

Block 12 sources of renewable and other excess energy can provide the operation of several digesters, transferring either thermal energy through additional insulated pipelines and valves 39, 40, 41, 42, or electric through an additional cable and a third switch 43.

Biogas plant works as follows. The biomass enters the extruder-mixer 2, where pre-accumulated hot water from the heat accumulator 18 is also fed through the valve 37. From the extruder-mixer 2, the crushed biomass is transferred to the hydrolysis fermentation chamber 3 and then, in the process of fermentation, to the acid chamber 4 and chamber 5 methane fermentation. Each chamber must have its own specific operating temperature, which is provided in the required quantities by supplying hot water to the heat exchangers 6, 7, 8 of chambers 3, 4, 5 of the digester through control valves 36, 35, 34, connected to the corresponding outputs 32, 31, 30 heat accumulator 18.

Preliminary accumulation of thermal energy in a heat accumulator with high heat capacity can be carried out from one or several renewable energy sources, as well as from electric networks with “failed” night energy at cheap rates, i.e. when networks have excess unclaimed energy. In particular, in the presence of hydraulic energy and the operation of a hydraulic turbine 14, the mechanical energy of which is transmitted through a multi-stage multiplier 15 to an electric generator 16, the latter generates electric energy for the first heating element 17, which heats the water in the heat accumulator.

In the presence of wind energy, the wind turbine 13 also rotates the multiplier 15, and at its outputs, in addition to the electric generator, a vortex heat generator 19 can be connected, supplying hot water through the valve 20 to the first heat accumulator 21 of the heat accumulator.

The solar collector 22 heats the hot water with sufficient solar insolation and transfers it through the valve 23 to the second heat exchanger 24 of the heat accumulator.

In the absence of energy from renewable sources, the heat accumulator 25 is connected via the first switch 26 to the electric network 27 during the operation of nightly low-cost tariffs, for example, using software relay hours (not shown in the drawing).

Electrical energy is supplied to the extruder-mixer 2, electric mixers 9, pumps 10 and other equipment requiring electric power through the normally closed contacts of the second switch 28 from the generator 16 or from the network 27 through the first switch 26 and previously closed contacts of the switch 28 during operation nightly rates.

Biogas from methane fermentation chamber 5 methane tank 1 enters gas tank 11 and then to consumers.

The fermented sludge from the chamber 5 is transferred to the separator 38, from one outlet of which the dry residue is also supplied to consumers as a valuable fertilizer, and the separated liquid, which has kept the heat of the digesters chambers, is sent back to the chambers through insulated pipelines. This liquid is saturated with methane bacteria, which contributes to their rapid reproduction and reduction of the total fermentation time.

This kind of liquid circulation: from the heat accumulator 18 to the extruder-mixer 2 for heating the biomass and then sequentially to the fermentation chambers 3, 4, 5, then from the chamber 5 to the separator 38, and from the separator 38 the still-cooled liquid is pressed into the chambers 4, 5 acidic and methane fermentation, creates the conditions for maximum savings of thermal and electrical energy. In addition, savings are also created due to the smaller required volume of make-up water from the line supplied to the inlet 29 of the heat accumulator 18, and, accordingly, lower energy costs for heating it up to the temperature of the total mass of water in the heat accumulator.

At present, usually digesters are heated by burning most of their own produced biogas or by heating the entire volume of liquid in the chambers from the mains for a day or more [1, 7, 8].

In the presence of a large central heat accumulator with sufficient heat capacity according to the proposed scheme and preliminary accumulation of thermal energy from renewable energy sources or from excess (unclaimed) electricity at the moment, it seems possible to significantly increase the biomass processing volumes by using several digesters in the biogas plant, into which hot water is supplied through valves 39, 40, 41, 42, and electricity through a third switch 43.

The proposed installation can be widely used, including in cold climate zones with a large number of degree-days of heating difference.

Information sources

1. Arbuzova E.V., Scheklein S.E. To the problem of energy efficiency of biogas technologies in the climatic conditions of Russia. // Alternative energy and ecology. 2011, No. 7, pp. 108-110.

2. Copyright certificate No. 1527191. THE USSR. IPC C02F 03/28. Bioenergy complex. IN AND. Selivanov, A.A Balanyuk et al. - No. 4276522; declared 07/06/87; publ. 12/07/89 (analog).

3. Patent No. 2065408 of the Russian Federation. IPC C02F 3/28; C02F 11/04. Biogas plant. A.K. Ilyin; O.P. Kovalev, V.A. Tymoshenko. - No. 94011881; declared 04/05/94; publ. 08/20/96. (analogue).

4. Yanko V.G., Yanko Yu.G. Wastewater and sludge treatment in digesters. Kiev, 1978, 120 p.

5. Viestur U.E., Kuznetsov A.M .; Savenkov V.V. Fermentation systems. - Riga, 1986, 174 p.

6. Copyright certificate No. 1583367 of the USSR. IPC C02F 3/28. Fermenter-gas holder. A.I. Elamanov. - No. 449484; declared 10/18/88; publ. 08/07/90. (analogue).

7. Copyright certificate No. 1800073 of the Soviet Socialist Republic. IPC F01K 13/00 Autonomous energy supply system for agriculture from non-traditional renewable energy sources. M.I. Gonchar et al. - No. 4866897/06; declared 06/05/90. Publ. 03/07/93. (Analog).

8. Patent No. 2073360 of the Russian Federation. IPC C02F 11/04. Installation for anaerobic digestion of organic waste with biogas production. E.S. Panzhava et al. Applicant EcoRos Center JSC. Claim 9405177/26 from 12.19.94. Publ. 02/10/97. (prototype).

9. Patent No. 2315721 of the Russian Federation. IPC C02F 3/28; C02F 11/04. The method of anaerobic processing of organic waste and installation for its implementation. V.V. Mokhov, E.V. Fomicheva. - 2006110378; declared 04/03/2006; publ. 01/27/2008. (analogue).

10. Copyright certificate No. 1353753 of the USSR. IPC C02F 11/04 Metantenk. A.A. Kovalev, V.P. Losyakov. - No. 4036561; declared 03/12/86; publ. 11/23/87. (analogue).

Claims (4)

1. Biogas plant for the digestion of organic waste, containing a thermally insulated digester, which includes hydrolysis, acid and methane fermentation chambers with heat exchangers in each chamber, an extruder-mixer, electric biomass mixers, pumps and pipelines, and the methane digester is connected to the methane fermentation chamber at the outlet gas tank and fermented biomass separator, characterized in that an additional block of renewable and other excess energy sources, consisting of a heat accumulator, is additionally introduced with two heating elements, two input heat exchangers, a solar collector, a wind power installation, a hydraulic turbine, a multi-stage multiplier and an electric generator, the solar collector being connected to a second heat exchanger, the outputs of a wind power installation and a hydraulic turbine connected to the inputs of a multi-stage multiplier, the output of the latter connected to a generator connected to the first TENU of the heat accumulator connected at the entrance to the cold water main, and its outputs with hot water are connected inens through valves to the extruder-mixer and heat exchangers of hydrolysis, acid and methane fermentation chambers. 2. Biogas plant according to claim 1, characterized in that a newly introduced vortex heat generator is connected to another output of the multiplier, and its output is connected to the first input heat exchanger of the heat accumulator. 3. Biogas plant according to claim 1, characterized in that two additional electrical switches are introduced, the second heater of the heat accumulator through the first switch connected to the excess energy networks, the second switch connected between the excess energy networks and the generator, and its output is connected to the extruder mixer, pumps and electric mixers digester. 4. Biogas plant according to claims 1 to 3, characterized in that it includes several digesters connected to a block of renewable energy sources by means of additionally introduced pipelines with valves and an additionally introduced cable with a third electric switch.