RU2644344C1 - Biological reactor for transforming gas-hydrogen hydrocarbons to biologically active compounds - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: reactor includes a fermentation tank, a heat exchanger, a pump for pumping water from the bottom to the upper cavity of the heat exchanger, a gas permeable polymeric tubular membrane for methane, a gas permeable polymeric tubular air membrane with an aerator function, an air receiver, a methane receiver, a gas-liquid separator, and a control device. Herewith the tubular membranes for methane and air occupy the entire volume of the fermentation tank, are arranged parallel to each other and with a gap between them for a free flow of the working fluid.

EFFECT: increasing the productivity and explosion safety of the biological reactor.

2 cl, 1 dwg

Description

The invention relates to equipment of fermentation processes for the conversion of gaseous hydrocarbons into biologically active compounds and can be used in the microbiological, food, medical, agricultural industries and in research practice.

The well-known "Fermentation unit for methane-assimilating microorganisms" (patent RU 2580646 from 04/10/2016).

The installation contains a column fermenter for carrying out aerobic cultivation processes and two reactors connected by pipelines of gas and liquid process streams, the fermenter comprising a casing, in the upper part of which there is an exhaust gas outlet pipe and a pipe for supplying nutrient salts and process water, feed components and seed biosuspension, in the lower part there is a nozzle for introducing a gas-liquid stream into the fermenter from the reactors and a nozzle for withdrawing the biosuspension from the fermenter to the reactor each reactor contains a nozzle for selecting a gas-liquid flow to the fermenter installed below the level of the culture fluid in the reactor, a disk stirrer with a drive installed at the level of the culture fluid in the reactor, a biosuspension feed pipe from the fermenter to the reactor, the first reactor contains a feed pipe connected at the top methane-containing gas, the second reactor contains an oxygen-containing gas supply pipe connected in the upper part, while the fermenter further comprises means for maintaining temperature, a means of maintaining the pH of the medium, a means of maintaining the level of dissolved oxygen, at least one off-gas analyzer, and the agitator drive in each reactor is equipped with a power measurement sensor connected via a logic controller to flow regulators of incoming gas flows and to control supply valves liquids to each reactor. The saturation of the working fluid with methane and oxygen is carried out in separate reactors, and the cultivation of microorganisms is carried out in a column fermenter, while the volume of the column fermenter is an order of magnitude greater than the total volume of 2 reactors.

The liquid saturated with methane in the first reactor and the liquid saturated with oxygen in the second reactor are pumped through pipelines to the column fermenter. In the fermenter, the liquids are mixed with the formation of a nutrient medium for the propagation of microorganisms.

The proposed solution has significant drawbacks.

Since the main energy substrate — methane and oxygen — is consumed by microorganisms in a mixture of dissolved gases, and the working fluid in the reactors is saturated with methane and oxygen separately, the liquid in the reactors cannot be a nutrient medium for cultivated microorganisms. In addition, microorganisms in the reactor volume will be in a transition process, which will delay the growth of microorganisms in the fermenter and, as a result, reduce the productivity of the installation.

The working fluid in the reactors is saturated with gases under high pressure and mixing with disk mixers, the operation of which is accompanied by the formation of fine foam, which negatively affects the metabolic processes in the working fluid and the allocation of target products.

Electric motors are used to drive the mixers, and surfactants are used to extinguish the foam, which increases the cost of manufactured products.

During the flow of gas-saturated liquids through pipelines, due to pressure differences in reactors and pipelines, partial degassing of liquids occurs with the formation of free bubbles of methane and oxygen, which reduces the concentration of dissolved gases in the working fluid entering the fermenter.

At the inlet of the fermenter, liquids saturated with dissolved gases are mixed with the formation of a nutrient medium that is actively consumed by multiplying microorganisms, and free bubbles of methane and oxygen rise into the gas cavity of the fermenter and accumulate in it with the formation of an explosive mixture.

The volume of fluid coming from the reactors to the fermenter is several times smaller than the volume of the working fluid in the fermenter, and therefore the zone of active growth of microorganisms in the fermenter will be measured by the volume of the fluid of the two reactors, and the rest of the volume of the working fluid in the fermenter will be inefficient.

In terms of the totality of negative signs, the described installation does not have the declared advantages.

The well-known "Bioreactor displacement with a membrane gas supply device" (patent RU 2446205 C1), comprising a cylindrical body, a cover, a bottom, a gas distribution device, gas-permeable polymer tubular membranes mounted along the axis of the housing, a heat exchanger pipe mounted inside the housing along its central axis, a gas supply pipe located in the cavity of the heat exchanger and connected to the gas distribution device, and a screw perforated surface with gas-permeable membranes.

The bioreactor begins with purging the membranes with working gas, after which the removal of working gas from the membranes is stopped, and the gas pressure in the membranes is increased to a predetermined value. As the concentration of cells increases, the gas pressure in the membranes increases.

Mass transfer in the bioreactor is carried out by the flow of culture fluid, along the helix, perpendicular to the surfaces of the membranes, which, according to the authors, helps to increase the productivity of the bioreactor.

The bioreactor has several disadvantages:

The gas distribution device is made in the form of a screw perforated surface, through the holes in which tubular membranes are passed. This design is metal-intensive and difficult to manufacture. In the process of the flow of the culture fluid through the bioreactor, due to the high resistance and lack of turbulence, zones with a zero flow velocity of the liquid are formed, which leads to the autolysis of microorganisms and a decrease in the productivity and quality of the target products.

The heat exchanger is installed along the axis of the bioreactor, which under conditions of insufficient mixing of the culture fluid leads to the formation of a temperature gradient that reduces the productivity of the bioreactor.

Fermentation processes proceed with the formation of a stable foam enriched in producing microorganisms, which is removed from the bioreactor in the exhaust gas stream to the atmosphere, which leads to a violation of the technological regulations, loss of biomass and a decrease in bioreactor productivity.

Fermentation processes are controlled by the rate of carbon dioxide production, which is possible only under strict aseptic conditions. In violation of aseptic conditions in the bioreactor, the concentration of carbon dioxide increases due to the respiratory activity of extraneous microflora and cannot be used to control fermentation processes.

The bioreactor does not provide conditions for the implementation of microbiological processes using gases that form explosive mixtures, for example, the cultivation of hydrogen-oxidizing or methane-oxidizing microorganisms, which significantly reduces the scope of the bioreactor.

The well-known "Bioreactor with a membrane device for the gas supply of microorganisms" (patent RU 2596396 from 08/10/2016).

The bioreactor contains a housing, a cover, a bottom, a heat exchanger, a gas distribution device, a methane collector, gas-permeable polymer methane membranes, pipes and pipelines for the flow of working liquids and gases.

The bioreactor also contains an aerator, gas-liquid separator, guide plates, diffuser, pump, bacterial filters for supply and exhaust gases, sensors: pH, T ° C and liquid level, exhaust gas damper, O ₂ and CO ₂ flow meters, CH ₄ pressure regulator, analyzer flue gas CH ₄ , O ₂ , CO ₂ and control device.

The bioreactor heat exchanger is made in the form of a heat exchange jacket mounted on the reactor vessel;

- the gas distribution device is equipped with a diffuser, directing the flow of aerating air into the gaps between the gas-permeable membranes;

- gas-liquid separator is made in the form of a tank and is equipped with a sensor for the level of the working fluid;

- the aerator is made in the form of a spray nozzle and placed in the cavity of the diffuser;

- as an aerator use a disk aerator company Matala, Australia.

A significant drawback of this bioreactor is the design of a gas distribution device, the dissolution of methane and oxygen in which is carried out in spaced and incommensurable volumes of the working fluid, and the mixing of the liquids is carried out with air bubbles obtained after dissolving air oxygen in a small volume of the diffuser of the gas distribution device.

Under these conditions, the active phase of consumption by a microorganism of a mixture of dissolved methane and oxygen will be limited by the small volume of the working fluid displaced from the diffuser under the influence of a gas lift. Further mixing of the volume of the working fluid saturated with methane in the absence of dissolved oxygen will be a transient low-productivity process.

Methane, which in the absence of dissolved oxygen is not consumed by microorganisms, but is discharged into the atmosphere, increasing the degree of explosion hazard of the apparatus, continues to flow into the ballast volume of the liquid, which makes up most of the working volume of the apparatus.

Sterilization of the bioreactor is carried out with significant losses of water vapor, which from the heat exchange jacket is discharged into the sewer.

Thermal control of the working fluid is carried out by introducing sharp water vapor into the heat exchange jacket, which leads to local overheating of the working fluid and reduces the quality of the fermentation products.

As a result of the operation of the described gas distribution device and heat exchanger, the reactor has low productivity, low efficiency, and a high degree of explosion hazard.

The purpose of the invention

Increasing the productivity, efficiency and explosion safety of a biological reactor due to the homogeneous dissolution of feed gases in the working fluid, which are the main energy substrate, while significantly reducing feed gas consumption, eliminating the formation of explosive volumes of a methane-oxygen mixture in the reactor and intensifying heat and gas exchange in the working fluid.

This goal is achieved in that the reactor containing:

- fermentation tank, aerator, heat exchanger, tubular gas-permeable membrane for methane, gas-liquid separator, exhaust gas analyzer, temperature sensor, pH sensor, pump for pumping the working fluid, methane pressure reducer, liquid level sensor, bacterial filter of exhaust gases, aseptic connectors, control device ,

Additionally contains:

- tubular gas permeable membrane for air with aerator function;

- an air pressure reducer installed at the entrance to the tubular gas permeable membrane for air;

- an air receiver equipped with an air pressure sensor and a valve for draining the condensate and in communication with the outlet of the tubular gas-permeable membrane for air;

- a methane receiver equipped with a methane pressure sensor and a condensate drain valve and in communication with the outlet of the tubular gas permeable membrane for methane;

- water transfer pump in the heat exchanger;

- a water heater installed in the heat meter;

- exhaust gas cooling coil installed in a gas-liquid separator,

wherein:

- tubular membranes for methane and air are placed across the entire volume of the fermentation tank parallel to one another and with a gap between them for a free flow of working fluid;

- tubular membranes can be made of a physiologically inert gas-permeable elastomer SKTN (synthetic rubber heat-resistant low molecular weight SKTN, GOST 13835-73).

The biological reactor according to the invention is schematically shown in the attached drawing and contains a fermentation tank 1, a lid 2, a heat exchanger 3, a heater 4, a methane pressure reducer 5, a methane tubular membrane 6, an air pressure reducer 7, an air tubular membrane 8, an air receiver 9, 10 methane receiver, gas-liquid separator 11, coil 12, exhaust gas filter 13, exhaust gas analyzer 14, pumps 15-16, aseptic connectors 17-18, heat exchanger temperature sensor 19, working fluid temperature sensor 20, dates pH sensor of working fluid 21, methane pressure sensor 22, air pressure sensor 23, hydraulic fluid level sensor 24, controlled valves 25-38, non-return valve 39, methane inlet fitting 40, air inlet fitting 41, acid and alkali solution inlet 42 for pH control, cold water inlet fittings 43-44, sterile nutrient inlet fitting 45, fermentation product discharge fitting 46, control device 47.

Reactor operation

To the fitting 40 connect a source of methane.

An air source is connected to the fitting 41.

A source 42 of an acid or alkali solution is connected to the fitting 42.

To the fittings 43-44 connect a source of cold water.

To the fitting 45 connect the source of the nutrient solution.

A fermentation product receiver is connected to the fitting 46.

From control unit 47:

Open the valve 36 and turn on the pump 16, through which the feed solution is introduced into the fermentation tank 1, through the aseptic connector 18, in the volume of the reactor being completely filled by the sensor 24 of the nutrient solution installed in the gas-liquid separator 11. When the nutrient solution contacts the sensor 24, the valve 36 is closed, after which the source of the original nutrient solution is disconnected from the fitting 45.

Open the valve 34.

The nutrient solution under the action of the pump 16 flows through the line in a closed circuit: fermentation tank 1 → gas-liquid separator 11 → fermentation tank 1, providing circulation mixing of the solution in the fermentation tank 1.

Valves 37, 29 are opened.

Water enters the heat exchanger 3 through the fitting 43 and the open valve 37, which when filling the heat exchanger 3 through the open valve 29 flows into the sewer. In these conditions, the valve 37 is closed, and on the control device 47 set:

- solution sterilization temperature;

- solution sterilization time;

- solution cooling temperature.

Using the control device 47, the Sterilization algorithm is used. Using the Sterilization algorithm, valve 28 closes, valve 30 opens, and heater 4 turns on.

The water in the heat exchanger 3 will begin to heat up while displacing the air from the jacket of the heat exchanger 3 through an open valve 29 into the sewer.

When the water temperature reaches 100 ° C by the sensor 19, the valve 29 will be closed, and the heating of the water will continue, increasing the temperature of the nutrient solution in the fermentation tank 1.

The heating of the nutrient solution will be accompanied by the removal of the vapor-air mixture from the fermentation tank 1, through a gas-liquid separator 11, a filter 13 and an open valve 30 into the drain sewer. At a temperature of the nutrient solution of 105 ° C according to the sensor 20, the valve 30 will close, and the temperature in the fermentation tank 1 will increase to a predetermined sterilization temperature of the nutrient solution and maintained by turning the heater 4 on and off on the sensor 20.

After the specified sterilization time has passed, the heater 4 will turn off, valves 37, 29 will open, through which cold water will flow, cooling the nutrient solution in the fermentation tank 1 to a predetermined temperature. When the desired cooling temperature of the nutrient solution is reached, a sensor 20 is triggered, according to which the valves 37, 29 are closed, and the temperature of the nutrient solution in the fermentation tank 1 is maintained by turning the heater 4 on and off by the sensor 20. The sterilization and cooling of the nutrient solution is completed by opening the valve 28.

Before carrying out the fermentation process:

On the gearbox 5 set the initial pressure of methane.

On the gearbox 7 set the initial air pressure.

A source of inoculum culture of microorganisms is connected to the fitting 45 of the aseptic connector 18.

Close valve 34.

Open the valve 36.

Through the operation of the pump 16, a predetermined volume of seed microorganisms is introduced into the fermentation tank 1, through an aseptic connector 18. At the end of sowing, the valve 36 is closed, the valve 34 is opened, and the source of the seed culture is disconnected from the nozzle 45 and the source of the sterile nutrient solution is connected in its place.

On the device 47 set:

- upper methane pressure in the receiver 10,

- lower methane pressure in the receiver 10,

- upper air pressure in the receiver 9,

- lower air pressure in the receiver 9,

- the upper pH of the working fluid,

- lower pH value of the working fluid,

- temperature of the working fluid,

- the number of reset cycles of the receiver 10,

- time of discharge of fermentation products,

and apply the algorithm "Process".

According to the "Process" algorithm:

Valves 25, 26 open.

Methane and air are introduced into the membranes 6, 8 under excess pressure given on the gears 5, 7, which flow through the tubular membranes and are pumped into the receivers 10, 9.

Upon reaching the specified gas pressures in the receivers 10, 9, the sensors 22 23 will work and the valves 25, 26 will close.

Valve 30 opens.

Cold water flows through the coil 12 and is discharged into the sewer.

Under the action of the pump 16, the working fluid from the gas-liquid separator 11 is continuously discharged into the fermentation tank 1 and distributed over multiple annular gaps formed by gas-permeable membranes 6, 8, inflated with methane and air.

Methane and air through the gas-permeable surfaces of the membranes 6, 8 enter the working fluid and saturate the working fluid with the formation of a mixture of dissolved gases, ensuring homogeneous multiplication of microorganisms in the reactor volume.

The metabolism of microorganisms involves methane, oxygen and carbon dioxide. Methane enters the working fluid through the wall of the tubular membrane for methane, and oxygen and carbon dioxide enter the working fluid through the wall of the tubular membrane for air.

Since oxygen and carbon dioxide occupy only 21% of the composition of atmospheric air, and the rest of the gas is nitrogen, which is not consumed by microorganisms, it is released from the working fluid in the form of gas bubbles and enhances the mixing of the working fluid flowing through the annular gaps of the membranes.

As a result of the respiration of breeding microorganisms, exhaust gases are released, which are displaced from the fermentation tank 1 into a separator 11, separated from the liquid, cooled by a coil 12 and, through a bacterial filter 13, a valve 28 and a gas analyzer 14, are vented to the atmosphere.

When the exhaust gases are cooled by the coil 12, condensate forms, which is removed from the separator 11 by the pump 16 to the fermentation tank 1.

The pH value of the working fluid is maintained by the sensor 21 with solutions of acid or alkali. When acidifying the working fluid to a predetermined lower pH value, valve 27 will open and an alkali solution will be introduced into the working fluid, and when restoring the working fluid to a predetermined upper pH value, an acid solution will be introduced into the working fluid through valve 27.

When microorganisms consume methane and oxygen and when exhaust gases are removed from the fermentation tank 1, the pressure of methane and air in the receivers 10, 9 drops to the specified lower values. From the sensors 22, 23 to the device 47, signals are received to open the valves 25, 26, through which the gas pressure in the receivers 10, 9 will be restored to the specified upper values. The valves 25, 26 after the restoration of gas pressures in the receivers 10, 9 are closed.

Each cycle of methane loading into the receiver 10 is fixed by the device 47 and, when a given number of cycles is realized, the pump 16 will turn off, the valve 35 will open and, through the aseptic connector 17 and the fitting 46, the fermentation products will be drained for a specified time. After the set drain time has elapsed, the valves 35, 34 will close, the pump 16 will turn on and the valve 36 will open, through which sterile nutrient solution will be introduced into the reactor 1 in the volume necessary for operation of the sensor 24 of the working fluid level. At the signal from the sensor 24, the valve 36 closes, the valve 34 opens, and the procedures for draining the fermentation products and introducing the nutrient solution into the tank 1 are repeated until the fermentation process is completed.

Valves 32, 33 are opened by blowing tubular membranes 6, 8 with methane and air, as well as when condensate is discharged from receivers 10, 9 into the sewer.

The check valve 39 is installed to prevent atmospheric air from entering the exhaust gas analyzer 14.

Valve 38 is used when completely draining water from the heat exchanger 3.

The efficiency of the biological reactor according to the invention

This provides an increase in the quality of the reactor, which is achieved through the integrated application of new technological and design solutions of this invention.

The dissolution of the feed gases in the cultivation medium is carried out by means of a tubular membrane for methane, which is placed parallel to the tubular membrane for air and close to one another in a fermentation tank with the formation of multiple annular channels for the free flow of working fluid. Both tubular membranes are made of a physiologically inert material with high molecular gas permeability and heat resistance, which ensures homogeneous propagation of microorganisms in the volume of the fermentation tank, prevents the penetration of foreign microorganisms into the working fluid, reduces the energy costs of gas dissolution, and increases the aseptic and explosion-proof reliability of the reactor.

Tubular membranes for methane and air occupy the entire volume of the fermentation tank, are parallel to one another and with a gap between them for the free flow of the working fluid, which ensures the dissolution of methane and oxygen in the working fluid with the formation of a mixture of feed gases homogeneously distributed throughout the volume of the fermentation tank .

Gases emitted by microorganisms during cultivation, as well as N ₂ , CO ₂ gases, which are not an energy substrate and make up 79% of atmospheric air, are used for bubble mixing of the working fluid in the annular channels of the membranes for methane and for atmospheric air.

Tubular membranes can be made, for example, from SKTN elastomer (synthetic heat-resistant low molecular weight rubber SKTN, GOST 13835-73).

The control of the fermentation process is carried out according to a given volume of methane consumed, which allows you to maintain the quality of the products obtained with each portion discharge.

The rate of replacement of the working fluid with a nutrient solution, as well as the purging of the working fluid with nitrogen from aerating air, maintains the concentration of dissolved carbon dioxide released by microorganisms during the fermentation process at a level that is not toxic for the multiplication of microorganisms.

Equipping the heat exchanger with a heater, a temperature sensor and a pump for circulating mixing of the coolant can significantly reduce energy losses during sterilization of equipment and nutrient solutions and improve the quality of thermal regulation of the working fluid in the fermentation process.

The reactor is made in the form of an autoclave, which can significantly reduce energy costs, intensify heat transfer and, thereby, significantly reduce the time for sterilization of equipment and nutrient solutions.

New conditions for the implementation of fermentation processes in a biological reactor do not depend on the geometric shape and size of the reactor during scaling and significantly expand the scope of the biological reactor.

Claims (2)

1. A biological reactor for converting gaseous hydrocarbons into biologically active compounds, including a fermentation tank with a lid, a heat exchanger, a gas-permeable polymer tubular membrane for methane, a temperature sensor for the working fluid, a pH sensor, a gas-liquid separator connected to the fermentation tank with a working fluid level sensor, connected to gas-liquid separator through a bacterial filter of exhaust gases, an analyzer of exhaust gases, as well as aseptic connectors for feeding the medium and microorganisms into the fermentation tank, control device and pipelines with valves for the flow of liquids and gases, characterized in that it further comprises a gas-permeable polymer tubular membrane for air with an aerator function, an air pressure reducer installed at the inlet to the tubular membrane for air , an air receiver equipped with a pressure sensor and a valve for draining condensate and connected to the outlet of the tubular membrane for air, a methane receiver equipped with a pressure sensor and a condensate drain valve and connected to the outlet of the tubular membrane for methane, a pump for pumping water from the lower to the upper cavity of the heat exchanger, a water heater installed in the lower cavity of the heat exchanger, an exhaust gas cooling coil installed in a gas-liquid separator for cooling and condensation of moisture from the exhaust gases . at the same time, tubular membranes for methane and air occupy the entire volume of the fermentation tank, are located parallel to one another and with a gap between them for the free flow of the working fluid. 2. The biological reactor according to claim 1, characterized in that the gas-permeable polymer tubular membranes are made of SKTN elastomer.

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