RU2769433C1 - Installation for obtaining feed biomass from natural gas - Google Patents

Abstract

FIELD: microbiological industry.

SUBSTANCE: invention relates to the microbiological industry, in particular to plants for growing microorganisms on natural gas, but can be used for growing microorganisms on other substrates. The plant for obtaining feed biomass from natural gas consists of n+1 sequentially installed fermenters. Fermenters are equipped with all necessary technological pipes, with recirculation systems of liquid and gas phases. The gas supply system is equipped with a carbon dioxide purification unit and is designed in such a way that all the gas components of the nutrient medium - natural gas and oxygen, designed for the entire installation, are fed to the first fermenter, and the exhaust gas mixture from the previous fermenter is fed to the next one. At the same time, the spent gas mixture is fed from the last fermenter to the bio-oxidizer. The spent gas mixture from the installation can be returned completely to the first fermenter. The input of all process water and biologically purified water into the installation is also carried out in the first fermenter. The selection of culture liquid from the plant is carried out only from the last fermenter to the separation stage, where the culture liquid thickens and the condensed biomass is fed to plasmolysis and drying of the finished product, while the spent culture liquid is fed into a bio-oxidant. The bio-oxidant is made similarly to fermenters, but has significantly lower mass transfer characteristics. The bio-oxidant additionally includes a secondary settling tank, where the microbial biomass of activated sludge is condensed, which is partially fed for recycling and centrifugation with further feeding it to drying to obtain an additional protein product, and biologically purified water (BPW) is fed to the first fermenter.

EFFECT: invention ensures the achievement of a technical result consisting in increasing the productivity of fermenters included in the installation and increasing the efficiency of using the components of the gas medium - natural gas and oxygen, ensuring a completely closed cycle of using process water.

4 cl, 2 dwg, 1 tbl, 1 ex

Description

The invention relates to the microbiological industry, namely to plants for growing microorganisms and can be used in growing microorganisms on natural gas.

Prior Art

For large-scale production of feed protein (FRP) from natural gas, two types of apparatus are mainly used worldwide: loop and jet fermenters.

Known application WO 2010/069313 "Apparatus for growing microorganisms", US patent No. 6.492.135 "Fermenter with a U-shaped and / or nozzle with a U-shaped loop and a method for carrying out the fermentation process" and US patent No. 10.184.103 "U -shape and/or Nozzle U-Loop Fermenter and Fermentation Method. The proposed devices are made in the form of loop fermenters and have a fairly simple design in the form of a vertical loop formed by two circuits - ascending and descending circuits of the gas-liquid flow.

Known patents for the invention of the USSR No. 1613484 "Apparatus for growing microorganisms", the USSR patent No. 1271061 "Apparatus for growing microorganisms" and the USSR patent No. 745930 "Installation for growing microorganisms", the proposed devices are jet and can be equipped with aerators (ejectors) drain type.

Methane mixed with air can form explosive mixtures. An air-gas mixture containing less than the lower flammable limit will not burn or explode. A mixture in which the content of natural gas is greater than the upper limit of flammability can be made to burn in a free flame by igniting a jet of this mixture as it flows into the atmosphere, but in a closed volume such a mixture does not burn and is not explosive. The explosive limits of methane-oxidizing mixtures ballosted with inert gases are shown on the triangular Gibbs-Rozeboom diagram (Figure 1).

The disadvantage of the above devices is that for the operation of loop fermenters, the technology developers have chosen the region of safe operation of the fuel-oxidizer-inert component system, the concentration region located above the MA line, with a maximum methane concentration of 6%. Thus, with an excess of oxygen, the cultivation process in this case is always carried out at the limit of natural gas, and the growth rate of methane-oxidizing microorganisms is limited by the rate of methane dissolution. The exhaust gas-air mixture with a methane content of up to 3% is released into the atmosphere, which does not allow achieving a high degree of natural gas utilization and contributes to environmental pollution.

In contrast, when working on jet devices, the safe operating area is below the MB line, but the safe operating area, in order to avoid any emergency situations and malfunctions, is limited to 8% oxygen in the entire range below the GW line. Thus, with an excess of methane, the cultivation process in this case is always carried out at a limit of oxygen, and the growth rate of methane-oxidizing microorganisms is limited by the rate of oxygen dissolution. The exhaust gas-air mixture with a natural gas content of up to 30%, oxygen 8% (the rest is nitrogen and carbon dioxide) enters the drying stage as fuel or waste heat boilers.

Thus, the disadvantage of the operation of these devices is that in both cases one of the components of the gas mixture is in the limit, and an unreasonably large amount of energy is spent on the other to dissolve it, but the consumption of which is limited by the other component.

In the 80s and early 90s of the last century in the USSR, for large-scale production of feed protein, technologies were used when working in air and on pure oxygen under pressure. If, when working in air, the fermentation process was quite stable over the entire range of operating pressure, then when working on pure oxygen, when the partial pressure of carbon dioxide reached about 1 atm, the fermentation process worsened, and with a further increase in the partial pressure of carbon dioxide, it dropped sharply. This is due to the inhibitory properties of carbon dioxide on the growth of microorganisms.

At one time, technical solutions for cleaning from carbon dioxide were proposed, for example, according to the USSR author's certificate No. 1306942, which was implemented at the Svetloyarsk BVK plant.

The disadvantage of the jet apparatus used in the Soviet Union was the operation of the apparatus at low oxygen concentrations in the gas phase, which was determined by the safety of the technological process and did not provide high mass transfer parameters of the fermenters, in view of the fact that the system fermenter - pipelines - burner of the dryer or waste heat boiler is not a closed volume and that during abnormal operation of the burner in the case of operation at an oxygen concentration in the gas phase of more than 12%, the flame from the burner through the pipeline can spread to the fermenter and an explosion of the gas phase will be inevitable.

The objective of the invention is to create a plant for producing fodder biomass from natural gas, providing an increase in the productivity of the fermenters included in the installation, reducing energy costs per unit of finished product and increasing the degree of use of the components of the gaseous medium (natural gas and oxygen), providing a completely closed cycle for the use of process water .

The technical result achieved by the invention is to increase the productivity of the fermenters included in the installation, reduce energy costs per unit of finished product and increase the degree of use of the components of the gaseous medium (natural gas and oxygen), ensuring a completely closed cycle for the use of process water.

This technical result is achieved by the fact that the installation for growing microorganisms consists of two or more sequentially installed fermenters, and the gas supply system of the installation is designed in such a way that all gas components of the nutrient medium (natural gas and oxygen), designed for the entire installation, are fed into the first the fermenter through the oxygen and natural gas supply fittings installed on the gas phase recirculation circuit, and the exhaust gas mixture from the previous fermenter is fed into the next one through the pipeline into the gas phase recirculation circuit of the subsequent fermenter, and the last fermenter has a fitting for the exhaust gas mixture outlet to the booster, which operates under the same pressure as the fermenters. Between the fermenters in the gas supply line, a carbon dioxide purification system is installed, which can be based on the sorption of carbon dioxide with cold water, alkaline solution or ethanolamines. The output of the exhaust gas mixture from the plant can only be carried out from the biooxidizer for disposal in waste heat boilers or to the dryer as a low-calorie fuel, or it can be completely returned to the first fermenter. The fittings for supplying the gas mixture from the previous fermenter to the next one are connected to the gas phase recirculation circuit of the subsequent fermenter. The input of all process water and biologically purified water into the plant is also carried out into the first fermenter, while the flow of cultural liquid from the first fermenter to the last one is carried out sequentially by circulation pumps, and the withdrawal of cultural liquid from the plant is carried out only from the last fermenter to the separation stage, where the cultural liquid is thickened. liquid and the supply of condensed biomass for plasmolysis and drying of the finished product, and the spent cultural liquid is fed into the biooxidizer. Each fermenter contains a housing with process pipes for supplying solutions of mineral salts, titrating agents, a jet aerator located vertically in the upper part of the housing and connected to a liquid phase recirculation system, the system including a heat exchanger, a liquid flow driver and pipelines designed to remove the liquid phase from the lower part of the housing and feeding it through the jet aerator to the upper part of the housing, and a pipeline connecting the side of the housing to the upper part of the aerator housing to ensure the recirculation of the gas phase. The biooxidizer is made similar to fermenters, but has significantly lower mass transfer characteristics. The bio-oxidation unit also includes a secondary settling tank, where the microbial biomass of activated sludge is settled, which is partially fed to recirculation and centrifugation with its further supply for drying to obtain an additional protein product, and biologically purified water (BWA) is fed to the first fermenter.

Description of the invention

In FIG. 1 shows a Gibbs-Roseboom diagram.

In FIG. 2 shows a diagram of the operation and elements of the installation for obtaining fodder biomass.

The installation for obtaining fodder biomass 1 from natural gas (see Fig. 2) consists of two or more serially installed fermenters 2, each fermenter includes a housing 3, a jet aerator 4 connected to a liquid phase recirculation system 5, which includes a heat exchanger 6, a flow driver liquid 7 and pipeline 8. Inside the housing 3 in its lower part, a bump 9 is coaxially installed in the form of a cone directed upwards. Also, the jet aerator 4 is connected to the gas phase recirculation system by pipeline 10. The input of all gas supply elements (oxygen and natural gas) into the installation is provided on the gas phase recirculation pipeline of the first fermenter in the direction of the gas phase through fittings 11 and 12. On the suction line of the stimulator flow rate 7, a fitting for supplying nutrient salts 13, process water 14 and titration solution 15 is installed; the selection of the gas mixture 18 from the previous fermenter to the next one through the pipeline 19 is connected to the recirculation circuit of the gas phase of the subsequent fermenter. Pipeline 19 between the fermenters is equipped with a carbon dioxide purification system37. Biooxidizer 20 is similar in design to fermenters. The installation also includes a separator 21, a plasmaizer 22, a dryer 23 and pipelines 24, 25 and 26. The equipment for biological treatment includes a secondary settling tank 27, a centrifuge 28, a dryer 29, pipelines 30, 31, 32, 33 and 34. For pipelines 35 and 36 are provided for the output of the spent gas-oxygen mixture from the bio-oxidizer.

Installation for fodder biomass works as follows.

In each of the fermenters 2 (F--1, F-2, F-3) in the installation for obtaining fodder biomass 1 from natural gas, the liquid flow activator (circulation pump) 7 takes the cultural liquid from under the bumper in the form of a cone 9 through the pipeline 8 and delivers it through the heat exchanger 6, where temperature control takes place, through the liquid phase recirculation system (pipeline) 5 to the jet aerator 4. Due to the fall of the liquid jet in the aerator 4, the gas phase is sucked from the upper part of the fermenter body 2 through the pipeline 10. Gas-liquid mixture from the jet aerator 4 falls to the surface of the liquid at high speed and, due to high potential energy, breaks through the entire layer to the baffle 9. There is an intensive mixing of the gas-liquid mixture and an intensive mass transfer between gas flows and the culture medium. Reflected from the bump stop 9, the gas-liquid mixture rises, where it is again sucked in by the falling jet and again directed downward. Part of the gas-liquid mixture from the body 3 is sucked by the liquid flow stimulator (circulation pump) 7 under the bump stop 9, where the culture liquid is partially degassed. Input of nutrient salts, process water and titrating agent is carried out through fittings 13, 14 and 15. The selection of cultural liquid for separation is carried out from the last fermenter 2 through pipeline 24. oxygen and natural gas required for the entire installation is produced through fittings 11 and 12, which are installed on the pipeline 10 of the fermenter 2 (F-1) in the direction of the gas phase in the installation. The gas mixture from each previous fermenter 2 enters the next one through the fitting 18 through the pipeline 19 into the pipeline 10 of the subsequent fermenter 2, with the exception of the last fermenter 2 (F-3), from which the gas phase through the fitting 16 is sent to the biooxidizer 20. On the pipeline 19 between fermenters in the gas supply line, a carbon dioxide purification system 37 was installed, which can be based on the sorption of carbon dioxide with cold water, alkaline solution or ethanolamine, which allows for 90-95% purification of the gas mixture from carbon dioxide. The number of fermenters to be installed in the plant is calculated in advance based on the requirement for the content of residual amounts of methane, oxygen and carbon dioxide at the outlet of the plant, necessary for the safe operation of the plant. Received on the separator 21 cultural fluid under the action of centrifugal forces thickens to a solids concentration of 18-20%. Condensed biomass through pipeline 25 enters the plasmolyzer 22, where it is inactivated at a temperature ^of 130 ° C. The spent cultural liquid through pipeline 26 enters the biooxidizer 20. From the plasmolyzer 22, the biomass through pipeline 26 enters the spray dryer 23, where it is dried to a moisture content of the finished product no more than ten%. The spent cultural fluid that enters the biooxidizer 20 (BO) is cleaned with activated sludge to the required values after it is returned to fermentation. Oxygen for the bio-oxidation process is the exhaust gas mixture from the last fermenter 2 (F-3). From the biooxidizer 20, the activated sludge suspension is sent to the secondary settling tank 27. The clarified biologically purified water (CPW) through the pipeline 33 enters the first fermenter 2 (F-1) as process water, and the condensed suspension is recycled through the activated sludge through the pipeline 31 into the biooxidizer 20 and through pipeline 30 to centrifuge 28, where it is further thickened to 50-60%. The condensed sludge enters the dryer 29 through pipeline 34, where it is dried to a moisture content of 8-10%, and which can also be used as protein feed, and the clarified liquid enters the secondary sump 27 through pipeline 32. The exhaust gas-air mixture with an oxygen content of not more than 12 % and a methane content of up to 70% from the oxidizer 20 through the fitting 16 is discharged through the pipeline 35 to the disposal system in the waste heat boilers (not shown in the diagram) or the dryer 23, or through the pipeline 36 it is returned to the first fermenter 2 (F-1). Since natural gas contains methane homologues and other impurities that cannot be used by methane-oxidizing microorganisms, and technical oxygen may also contain similar impurities, these impurities can accumulate in a closed gas supply system, as evidenced by gas analyzers, and then it will be necessary to discharge the gas phase of the plant to the disposal system (not shown in the diagram).

An example of the operation of a plant for growing microorganisms on natural gas

Initial data

Expenditure coefficients (we take average values):

α _CH4 \u003d 1.3 kg CH ₄ / kg DIA or 1.83 nm ³ / kg DIA

α _O2 \u003d 3.7 kg O ₂ / kg DIA or 2.58 nm ³ / kg DIA

α _CO2 = 1.7 kg CO ₂ / kg DIA or 0.867 nm ³ / kg DIA

Densities of gases included in the gas mixture:

ρ _CH4 \u003d 0.71 kg / m ³ ; ρ _O2 \u003d 1.43 kg / m ³ ; ρ _CO2 \u003d 1.96 kg / m ³ ; ρ _N2 \u003d 1.25 kg / m ³

Characteristics of the fermenters included in the installation

Geometric volume - 100 m ³ ;

Working volume - 70 m ³ ;

Working pressure - 0.4 MPa;

Number of fermenters at the plant - 3

Number of bio-oxidants - 1

Volumetric mass transfer coefficient of fermenters - 1500 h ^-1 ;

The growth rate of the methane-oxidizing culture is 4 hours.

We continuously feed into the installation:

- oxygen 3000 nm ³ /h;

- methane 4000 nm ³ /h;

In this case, the initial concentration of oxygen will be 42.85%, and methane - 57.15%.

We assume that the oxygen utilization factor will be 50% in each fermenter.

The main parameters of the installation are presented in Table 1.

The amount of oxygen used for the biooxidation process was calculated using the equation:

Q _O2 ^cons. = α (BOD _in – BOD _out ) x Q _W , (1)

where α is the respiration coefficient (for our case, 1.5), BOD _in , BOD _out are the biological oxygen consumption at the inlet and outlet of the biooxidizer, respectively, Q _W - TLC, m ³ / h.

BOD _in = 1500 mg O ₂ /l (according to the data from the operating installation of the Svetloyarsky plant) BVK, BOD _out = 100 mg O ₂ / l (according to the quality requirements of biologically treated water for the production of fodder biomass from natural gas), then

Q _O2 ^cons. \u003d 1.5 (1500 - 100) x 52.5 \u003d 110.25 kg O ₂ / h.

At the same time, the degree of oxygen utilization throughout the installation is 91.17%, methane - 100%, with its full return from the biooxidizer to the first fermenter. The concentration of carbon dioxide in the exhaust gas of 19.3% at a pressure of 0.4 MPa does not lead to inhibition of the process of biosynthesis of methane-oxidizing microorganisms. In addition, the gas-air mixture leaving the biooxidizer is not explosive and flammable, and the oxygen-methane mixture in the fermenters is also not explosive, because It is located in a closed volume, where neither a spark nor an open flame can reach.

If we consider the classical version of obtaining microbial biomass of methane-oxidizing microorganisms under equal conditions for mass transfer, working pressure and working volume, then the productivity of fermenters will be

Q \u003d (K _La × Δ C) × V _slave / α _O2 , (2)

where K _La is the volumetric mass transfer coefficient, h ^-1 ; Δ С is the driving force of the mass transfer process, mg/l; V _slave - the working volume of the fermenters, m ³ .

The driving force of the mass transfer process is determined by the equation:

Δ C = C^X - WITH_R = (P × H × y_O2 ^exit ) - WITH_R, (3)

where P is the pressure of the system, kg/m ² , H is the Henry constant, atm ^-1 (for our case, approximately 29), y _О2 ^out is the volume concentration of oxygen at the outlet of the apparatus, _Ср is the working concentration of oxygen in the liquid, mg/ l (for our case, approximately 1.0).

Then: Δ C \u003d (4 × 29 × 0.08) - 1.0 \u003d 8.28 mg / l,

and Q \u003d (1500 × 8.28) / 1000 × 210 / 3.7 \u003d 702.4 kg / h.

As can be seen from the above calculations, the proposed scheme for growing microorganisms on natural gas provides a productivity of more than 40% higher than with the classical scheme for growing microorganisms.

The proposed technical solution makes it possible to ensure safe operation, increase productivity by more than 1.4 times and, as a result, reduce energy costs per unit of finished product, increase the degree of oxygen use up to 91% and methane up to 100% with its full return from the biooxidizer to the first fermenter and ensure completely closed cycle of process water use.

All of the above indicates the industrial applicability of the proposed plant for obtaining fodder biomass from natural gas.

Information sources

1. IZ-Strahlfermentor.Techn.Inform.VEBChemianlagenbaukombinat. Leipzig-Grimma, 1983.

2. U.E. Viestur, A.M. Kuznetsov, V.I., Savenkov. fermentation systems. Riga, "Zinatne", 1986.

List of positions

1. Installation for obtaining fodder biomass

2. Fermenter (F-1, F-2, F-3)

3. Fermenter body,

4. Jet aerator

5. Liquid phase recirculation system

6. Heat exchanger

7. Fluid flow stimulator

8. Pipeline

9. Cone-shaped chipper

10. Pipeline

11. Connection for the movement of the gas phase

12. Connection for the movement of the gas phase

13. Nutrient salt supply fitting

14. Process water inlet

15. Titration solution inlet

16. Exhaust gas outlet

17. Union for the selection of cultural fluid

18. Gas mixture selection fitting

19. Pipeline

20. Biooxidizer

21. Separator

22. Plasma machine

23. Dryer

24. Pipeline

25. Pipeline

26. Pipeline

27. Secondary clarifier

28. Centrifuge

29. Dryer

30. Pipeline

31. Pipeline

32. Pipeline

33. Pipeline

34. Pipeline

35. The pipeline for the output of the exhaust gas-oxygen mixture

36. The pipeline for the output of the exhaust gas-oxygen mixture

37. Carbon dioxide purification system.

Claims (4)

1. An installation for producing fodder biomass from natural gas, including: jet fermenters, each of which contains a housing with process fittings for supplying solutions of nutrient salts, titrating agents, a jet aerator located vertically in the upper part of the housing and connected to a liquid phase recirculation system, moreover the plant additionally includes a heat exchanger, a liquid flow driver and pipelines made with the possibility of withdrawing the liquid phase from the lower part of the fermenter housing and supplying it through the jet aerator to the upper part of the fermenter housing, and a pipeline connecting the side of the jet fermenter housing to the upper part of the aerator to ensure recirculation gas phase, and inside the body of the jet fermenter, in its lower part, a bumper is installed coaxially in the form of a cone directed upwards, while each jet fermenter contains a fitting for the selection of cultural liquid, the installation also includes: a separator where thickening cultural liquid and supply of condensed biomass for plasmolysis and drying of the finished product; a bio-oxidizer, into which the spent cultural fluid is supplied from the separator, which includes a secondary settling tank, where the activated sludge microbial biomass is settled; a centrifuge where the activated sludge is thickened, and an activated sludge dryer, characterized in that the installation for producing fodder biomass consists of n + 1 jet fermenters installed in series, and the gas supply system of the installation is configured to supply all gas components of the nutrient medium calculated for the entire installation into the first jet fermenter through the oxygen and natural gas fittings installed on the gas phase recirculation circuit, and the exhaust gas mixture from the previous jet fermenter is fed into the next one through the pipeline into the gas phase recirculation circuit of the subsequent jet fermenter, while only the last jet fermenter has a waste gas outlet blends into a bio-oxidizer that operates at the same pressure as jet fermenters. 2. The installation for producing feed biomass from natural gas according to claim 1, characterized in that the first jet fermenter is configured to introduce all process water and biologically purified water into the installation, while each jet fermenter is configured to introduce a balanced mineral nutrition solution into in accordance with its performance, and the liquid flow driver is configured to ensure the flow of cultural liquid from the first jet fermenter to subsequent ones, and the last jet fermenter is configured to take the cultural liquid from the installation. 3. Installation for obtaining fodder biomass from natural gas according to claim 1, characterized in that a carbon dioxide purification system is installed between the jet fermenters in the gas supply line. 4. The plant for producing fodder biomass from natural gas according to claim 1, characterized in that the biooxidizer is configured to withdraw the exhaust gas mixture from the installation for disposal to waste heat boilers or to the dryer as a low-calorie fuel, or to return the exhaust gas mixture completely to the first jet fermenter.

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