RU2814474C2 - Improved loop fermenter - Google Patents

Abstract

FIELD: fermentation.

SUBSTANCE: fermentation reactor including a loop part and an upper tank, wherein this loop part includes a downflow part connected to an upflow part through a U-shaped part, wherein the upper tank includes: (i) a first outlet connecting the upper tank having a downflow part of the loop part and allowing the fermentation liquid present in the upper tank to flow from the upper tank to the loop part; (ii) a first inlet connecting the upper tank to the upflow part of the loop part and allowing the fermentation liquid present in the loop part to flow from the loop part to the upper tank; and (iii) a vent pipe to discharge waste gases from the upper tank. The upper tank further includes a visual observation means located at an end of the upper tank providing a view from the first inlet to the first outlet with a substantially horizontal field of view.

EFFECT: invention provides visual monitoring of the development of foaming during fermentation.

7 cl, 1 dwg

Description

Field of technology to which the invention relates

The present invention relates to an improved fermentation reactor. In particular, the present invention relates to an improved fermentation reactor including a loop portion and an upper tank.

State of the art

In methanotrophic fermentations, degassing in the overhead tank is of utmost importance because insufficient degassing of the fermentation liquid results in the release of waste gases like CO ₂ which, in certain quantities, can accumulate and become toxic to the methanotrophic organisms fermenting in the fermentation reactor.

During fermentation, using a fermentation reactor including a loop portion and an upper reservoir, also called a loop reactor, the fermentation liquid circulates from the upper reservoir to the downflow portion, through the U-shaped portion to the upflow portion, and returns to the upper reservoir. When fermentation liquid enters the upper reservoir, foaming develops due to the availability of free space above the liquid level in the upper reservoir.

Controlling the development of foaming during fermentation is important because excessive foaming can create a risk of a fermentation process in which excessive foaming can increase the risk of explosions because the gas in the foam may primarily be methane, and when the gas is released, the concentration of methane can be significant. increase and create a ratio with oxygen within the explosive range.

In case of formation of excessive amounts of foam, an antifoaming agent is used, which may result in the suspension of the fermentation process and the risk of a possible restart of the fermentation process.

Electronic foam detectors or sensors have traditionally been used to control extensive foaming. However, the challenge with using electronic foam detectors/sensors is that when they are activated, the fermentation process stops and from time to time the fermentation process must be restarted. Another possibility may be to increase the anti-foaming of the fermentation liquid in order to reduce the development of foaming in accordance with the above description of the invention, using "treatments" in relation to excessive development of foaming. As mentioned before, the disadvantages of using anti-foam agents are the formation of the gas responsible for foam build-up, mainly methane, and when this is released, the concentration of methane in the upper reservoir instantly and significantly increases. At high foam levels, the concentration of methane becomes even higher and the ratio between methane and oxygen may fall within the explosive range, which must be avoided. In addition, when foaming agents are added to the fermentation liquid, degassing may be impaired, and the addition of methane must be stopped, and the cells may periodically suffer from starvation.

Thus, an improved fermentation reactor would be advantageous, and in particular a more efficient and/or reliable fermentation reactor in which it is possible to control both under-foaming and excessive foaming, in which degassing can be improved, in which delays are reduced or are excluded, and costs can be reduced when fermentation on methanotrophic organisms would be preferential.

The essence of the invention

Thus, one object of the present invention relates to an improved fermentation reactor.

In particular, one object of the present invention is to provide a fermentation reactor that solves the above-mentioned problems of the prior art associated with degassing, and at the same time avoids excessive excessive foaming while reducing the risk of explosions, the risk of possible termination of the fermentation process and the occasional possible restart.

Thus, one aspect of the invention relates to a fermentation reactor including a loop portion and an upper reservoir, wherein said loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion, wherein the upper reservoir includes:

(i) a first outlet connecting the upper reservoir to the downflow portion of the loop portion and allowing the fermentation liquid present in the upper reservoir to flow from the upper reservoir to the loop portion;

(ii) a first inlet connecting the upper reservoir to the upflow portion of the loop portion and allowing the fermentation liquid present in the loop portion to flow from the loop portion to the upper reservoir; And

(iii) a vent pipe to discharge waste gases from the upper tank;

Where

the upper reservoir further includes a means of visual observation.

Another aspect of the present invention relates to a fermentation process involving at least one methanotrophic organism or co-fermentation involving at least one methanotrophic organism, wherein the method includes the step of:

(a) adding at least one methanotrophic organism; necessary substrates such as nutrient salts, pH adjusting components and water; and at least one gaseous substrate component

into a fermentation reactor including a loop portion and an upper reservoir, wherein said loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion, wherein the upper reservoir includes:

(i) a first outlet connecting the upper reservoir to the downflow portion of the loop portion and allowing the fermentation liquid present in the upper reservoir to flow from the upper reservoir to the loop portion;

(ii) a first inlet connecting the upper reservoir to the upflow portion of the loop portion and allowing the fermentation liquid present in the loop portion to flow from the loop portion to the upper reservoir; And

(iii) a vent pipe to discharge waste gases from the upper tank;

Where

the upper reservoir further includes a means of visual observation.

Yet another aspect of the present invention relates to the use of a fermentation reactor including a loop portion and an upper reservoir, wherein said loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion, wherein the upper reservoir includes:

(i) a first outlet connecting the upper reservoir to the downflow portion of the loop portion and allowing the fermentation liquid present in the upper reservoir to flow from the upper reservoir to the loop portion;

(ii) a first inlet connecting the upper reservoir to the upflow portion of the loop portion and allowing the fermentation liquid present in the loop portion to flow from the loop portion to the upper reservoir; And

(iii) a vent pipe to discharge waste gases from the upper tank;

Where

the upper reservoir further includes a visual observation means;

for fermentation on at least one methanotrophic organism.

Brief description of the figures

Figure 1 shows the upper reservoir (1) of a fermentation reactor for fermentation on at least one methanotroph, including a loop part and an upper reservoir (1). Here, the loop portion (not shown in the figure) includes a downflow portion (not shown) connected to an upflow portion (not shown) through a U-shaped portion (not shown), where the upper reservoir (1) includes: (i ) a first outlet (2) connecting the upper reservoir (1) with the downflow part of the loop part and allowing the fermentation liquid present in the upper reservoir (1) to flow from the upper reservoir (1) to the loop part; (ii) a first inlet (3) connecting the upper reservoir (1) with the upflow part of the loop part and allowing the fermentation liquid present in the loop part to flow from the loop part to the upper reservoir (1); and (iii) a vent pipe (5) for discharging waste gases from the upper tank. In the illustration shown in Figure 1, the upper tank (1) is equipped with a product outlet (4) intended for obtaining biomass (fermentation product). In another embodiment, the product outlet may be located in a loop portion of the fermentation reactor, preferably in a U-shaped portion of the loop portion. The upper reservoir (1) is also equipped with a visual observation means (6), in particular the visual observation means (6) can be provided in the form of a viewing hole or in the form of a viewing glass (6), optionally in combination with a recording camera. In addition to the visual monitoring means (6), the upper reservoir (1) may be equipped with at least one foam sensor (8) inside the upper reservoir. If the foam level increases, one way to reduce the foam level may be to add an antifoam agent through the antifoam inlet (9). To improve visual observation, the upper tank (1) can be equipped with a light source (7). The light source can be provided as a separate element or as an integrated element in the sight glass (6).

The present invention will now be described in more detail in the following.

Detailed Description of the Invention

Accordingly, as the inventor of the present invention has surprisingly discovered, controlling the foaming and turbulence in the fermentation liquid in the upper tank of a U-loop reactor has a significant impact on off-gas degassing. Thus, ensuring that sufficient foaming is achieved as well as sufficient turbulence in the fermentation liquid results in improved performance for the fermentation process. Thus, it is of interest to obtain a stable foaming rate for the fermentation liquid.

Thus, one preferred aspect of the present invention relates to a fermentation reactor including a loop portion and an upper reservoir, wherein said loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion, wherein the upper reservoir includes:

(i) a first outlet connecting the upper reservoir to the downflow portion of the loop portion and allowing the fermentation liquid present in the upper reservoir to flow from the upper reservoir to the loop portion;

(ii) a first inlet connecting the upper reservoir to the upflow portion of the loop portion and allowing the fermentation liquid present in the loop portion to flow from the loop portion to the upper reservoir; And

(iii) a vent pipe to discharge waste gases from the upper tank;

Where

the upper reservoir further includes a means of visual observation.

The U-shaped portion of the loop reactor may be connecting the bottom of the downflow portion to the bottom of the upflow portion. Moreover, the upper part of the upflow part may be connected to a first inlet connecting the upper reservoir to the upper part of the upflow part. The first outlet may be connecting the upper reservoir to the top of the downflow portion.

As used herein, the term "fermentation reactor" refers to a reactor including an upper reservoir connected to the upper ends of a downflow portion and an upflow portion. The downflow part and the upflow part are connected at the lower ends through a U-shaped part.

Conventional fermenters are stirred tanks that may or may not have recirculation systems or sampling channels. With these types of fermenters or reactors, mixing of gases with the fermentation liquid is accomplished by using agitator blades located centrally in the fermenter, and gaseous substrates are added to the agitated reservoir. The stirrer blades create turbulence in the liquid, which means the gas, usually injected in the lower region of the reactor, is dispersed into the liquid in the form of small, fine gas bubbles. Gaseous substrates are added in the lower region of the agitated tank and must be compressed to overcome the hydraulic pressure in the tank into which they are pumped. This compression of gases requires the use of significant amounts of energy.

This type of reactor ensures that relatively homogeneous mixing is achieved, that is, approximately the same concentrations of gases and substrates will be detected when measured either in the upper or lower regions of the reactor. But intensive mixing to create small gas bubbles and achieve optimal mixing in the tank also requires the use of excess energy and, in addition, involves significant heating of the fermentation liquid. Excessive energy use makes this type of reactor uneconomical, especially for low-cost products such as microbial cells, which are currently sold as animal feed or fish feed.

With the intention of reducing energy consumption for mixing, but still ensuring sufficient mass transfer of gases into the liquid phase, other types of fermenters have also been developed. These fermenters are often called airlift fermenters, jet loop fermenters, or U-loop fermenters.

In order to avoid mechanical mixing, various types of airlift reactors have been developed. Most of these reactors are so-called loop reactors, having two sections: an upflow part and a downflow part, which are mutually coupled at both ends. Gases are introduced as small bubbles in the lower region of the reactor in the upflow portion, usually in a nozzle arrangement. The bubbles mix with the liquid, causing the overall density to decrease and the gas-liquid mixture to rise while being displaced by new liquid emerging from the downflow portion. The gas-liquid mixture moves upward through the upflow portion of the reactor and releases gas bubbles in the upper region. The liquid then flows down through the downflow section. In order to obtain a long residence time of gas bubbles in the liquid. Airlift reactors are typically very tall elongated reactors and the gas must be supplied at high pressure to overcome the hydrostatic pressure in the lower region of the reactor. For gas in the form of air, this involves the use of compressors. Compressing air usually requires the use of significant amounts of energy.

Airlift reactors demonstrate relatively poor utilization of the injected gas. Typically, only 20-40% oxygen gas is used. It is often difficult to obtain good and rapid release of gas bubbles from the fermentation liquid in the upper region of the reactor and to separate the gas phase thus produced (which may rather represent foaming) from the liquid phase before the liquid flows into the downflow portion of the reactor. Thus, the gas phase, including significant amounts of fermentation waste gases such as CO ₂ , is trapped in the broth and is then redispersed in the broth, which can result in reduced solubilization of the support gases added to the fermenter.

The U-loop reactor according to the description of the present invention has a simple structure and is designed to ensure the injection of uncompressed or nearly uncompressed gaseous substrate into the U-shaped portion in combination with a long residence time of the gases throughout the U-shaped portion and thus high degree of utilization of injected gases. The upper region of the reactor includes an upper reservoir, which is designed to achieve good gas-liquid separation.

As used herein, the term "loop reactor" refers to one specific example of a fermentation reactor. The loop reactor according to the present invention includes an upper reservoir and a loop portion. Preferably, the loop reactor according to the present invention may be a U-shaped loop reactor.

The term "loop reactor" according to the present invention may preferably be defined by having a length of the loop portion, which may be greater than the length and/or height of the upper reservoir. Preferably, the loop reactor or fermentation reactor according to the present invention may include a loop portion having a length that is greater, preferably substantially greater, than the length and/or height of the upper tank.

In one embodiment of the present invention, the fermentation reactor according to the present invention may include a loop portion having a length that is greater, preferably substantially greater, than the length and/or height of the upper tank.

In one further embodiment of the present invention, the length of the loop portion is at least 125% (v/v) greater than the length and/or height of the upper reservoir; such as at least 150% (v/v); for example, by at least 200% (v/v); such as at least 300% (v/v); for example, by at least 400% (v/v); such as at least 600% (v/v); for example, by at least 800% (v/v); such as at least 1000% (v/v); for example, by at least 1500% (v/v); such as at least 2000% (v/v); for example, by a value in the range of 125-2000% (v/v); thus, by a value in the range of 150-1500% (v/v); for example, by a value in the range of 200-1000% (v/v); thus, by a value in the range of 300-800% (v/v); for example, by a value in the range of 400-600% (v/v).

In yet another embodiment of the present invention, the fermentation reactor according to the present invention may include a loop portion having a length that may be greater, preferably substantially greater, than the length and/or height of the upper tank; and the volume of the upper reservoir is greater than the volume of the loop part.

The loop part of the present invention relates to the downflow part, the upflow part, as well as the connecting parts at the lower ends of the upflow part and the downflow part formed by the U-shaped part. Thus, the term "loop portion" refers to a fermentation reactor in the absence of an overhead tank.

As used herein, the term "U-piece" refers to the bend formed at the bottom of a fermentation reactor or loop reactor and connecting the lower ends of the upflow portion and the downflow portion. Preferably, the upflow portion and the downflow portion are vertical or substantially vertical.

The fermentation reactor according to the present invention includes a loop portion and an upper reservoir, wherein the loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion. The U-shaped portion of the present invention may include a substantially horizontal connecting portion that connects the lower end of the downflow portion to the lower end of the upflow portion.

In one preferred embodiment of the present invention, the fermentation reactor and/or loop reactor according to the present invention may be a U-shaped loop reactor.

In one further embodiment of the present invention, the downflow portion and the upflow portion have substantially identical vertical lengths. In the present context, the term "vertical length" refers to a downflow portion or an upflow portion, where the vertical upflow portion may be one downflow portion or one upflow portion, or it may be divided into two or more vertical portions. downflow parts or two or more vertical upflow parts, which in combination (combinations of two or more downflow vertical parts or combinations of two or more upflow vertical parts) constitute a downflow vertical part or a vertical part with an upward flow.

The length of the horizontal connecting portion may vary depending on the type of loop reactor proposed and/or used.

The fermentation reactor can be designed as a vertical loop fermenter or a horizontal loop fermenter.

In one embodiment of the present invention, the fermentation reactor may be a vertical loop reactor. The term "vertical loop reactor" may refer to a loop reactor including a main U-shaped portion in a vertical or substantially vertical position relative to a horizontal position. In one embodiment of the present invention, the fermentation reactor includes a main U-shaped portion in a vertical or substantially vertical position.

In another embodiment of the present invention, the fermentation reactor may be a horizontal loop reactor. The term "horizontal loop reactor" may refer to a loop reactor including a main U-shaped portion in a horizontal or substantially horizontal position relative to a vertical position. In one embodiment of the present invention, the fermentation reactor includes a main U-shaped portion in a horizontal or substantially horizontal position.

Preferably, the fermentation reactor may be designed as a vertical loop fermenter.

In the context of the present invention, the term "main portion" refers to at least 51% (v/v) of the U-shaped portion having the desired position; thus as to at least 55% (v/v); for example, to at least 60% (v/v); thus to at least 65% (v/v); for example, to at least 70% (v/v); thus to at least 75% (v/v); for example, to at least 80% (v/v); thus to at least 85% (v/v); for example, to at least 90% (v/v); thus to at least 95% (v/v); for example, to at least 98% (v/v).

The U-shaped part of the fermentation reactor of the present invention can be designed in various ways.

In one embodiment of the present invention, the loop portion may be designed to have one downflow portion and one upflow portion connected using a U-shaped portion.

In yet another embodiment of the present invention, the downflow portion and/or the upflow portion may include two or more regions of the downflow portion and/or the upflow portion. Examples of two or more regions of a downflow portion and/or an upflow portion can be found in WO 2018/132379, which is incorporated herein by reference.

In the present context, the term "top tank" refers to a container located in the upper area of the fermentation reactor and responsible for removing waste gas from the fermentation liquid. Preferably, the upper reservoir is only partially filled with fermentation liquid during operation/fermentation. In one embodiment of the present invention, the term "partially filled with fermentation liquid" refers to a 90:10 ratio between fermentation liquid and gas; thus, as to the ratio 80:20; for example, to a ratio of 70:30; thus, as to the ratio 60:40; for example, to a 50:50 ratio; thus, as to the ratio 40:60; for example, to a ratio of 30:70; thus, as for the ratio 20:80; for example, to a ratio of 10:90.

In the context of the present invention, the term "visual means" refers to one or more means allowing those skilled in the art to obtain direct information regarding the foaming characteristics of the overhead reservoir.

In one embodiment of the present invention, the immediate information may be real-time information regarding the foaming characteristics of the overhead tank.

In one further embodiment of the present invention, the foaming characteristics of the top tank may include foam density, foam height, and turbulence level obtained in the top tank.

Turbulence in the upper tank can be produced in the fermentation liquid present in the upper tank by forcing the fermentation liquid from the upflow portion through the first inlet into the upper tank.

Foam density may be an expression of the size of the bubbles in the foam. The larger the bubbles in the foam, the lower the foam density will be, and the lower the value will be kg of foam/m ³ . The smaller the bubbles in the foam, the greater the foam density, and the greater the value kg of foam/m ³ .

In one embodiment of the present invention, the visual observation means may be positioned to provide a horizontal or substantially horizontal field of view.

In one further embodiment of the present invention, visual viewing means may be located on the side of the upper reservoir, allowing a combined view above the surface of the fermentation liquid and below the surface of the fermentation liquid.

Preferably, the visual observation means may be located at the end of the upper reservoir.

Even more preferably, the viewing means may be located at the end of the upper reservoir, providing a view from the first inlet (or upflow portion) to the first outlet (or downflow portion).

In one embodiment of the present invention, the visual observation means may be a viewing hole, a camera, or a combination of a viewing hole and a camera.

Preferably, the viewing hole may be a viewing glass.

The filming camera may be an in-line filming camera.

In one embodiment of the present invention, the top tank may be equipped with a light source to improve visual observation within the top tank. The light source may be provided as a window allowing ambient light to enter the upper reservoir, and/or as an artificial light source introduced into the upper reservoir.

In one further embodiment of the present invention, the light source may be provided as a separate element (eg, as a separate artificial light source) or as an integrated element (for example, as an integrated artificial light source) in the sight glass.

In addition to the visual monitoring means, the upper reservoir may be equipped with at least one foam sensor within the upper reservoir.

In order to avoid excessive development of foam and/or take measures to handle it, an antifoam agent may be added to the fermentation liquid. Thus, the upper reservoir can be equipped with an anti-foam inlet.

The fermentation reactor may be equipped with one or more sensors to control the level and/or addition of gaseous substrates, water, mineral nutrients, and the like.

In one embodiment of the present invention, the fermentation reactor, preferably the loop portion, includes a sensor or ion analyzer for determining the level of one or more ionic species in the fermentation liquid, preferably one or more ionic species selected from phosphate, calcium, hydrogen, nitrate, nitrite and/or or ammonium, preferably nitrate and/or nitrite.

In one further embodiment of the present invention, the loop reactor may be equipped with a circulation pump. The circulation pump may preferably be located in the loop portion of the loop reactor.

Preferably, the circulation pump may be located in the upper half of the downflow portion.

In one embodiment of the present invention, the fermentation reactor may include a device for reducing flow. Preferably, the flow reducing device may be inserted upstream of the first inlet in the upper half of the upflow portion.

In one further embodiment of the present invention, the loop portion of the fermentation reactor may preferably include one or more gas inlets; one or more water inlets; and/or one or more fermentation medium inlets.

One or more gas inlets; one or more water inlets; and/or one or more inlets for the fermentation medium can be controlled using a computer. Preferably one or more gas inlets; one or more water inlets; and/or one or more inlets for the fermentation medium can be controlled using a computer based on data received from one or more sensors or analyzers.

In order to provide improved fermentation conditions, it may be important to distribute a gaseous substrate, such as methane, in the fermentation liquid. Thus, the loop portion of the fermentation reactor may include one or more active devices for distributing gas into the fermentation liquid.

In one embodiment of the present invention, one or more active devices for distributing gas in the fermentation liquid is a micro- or nanobubbler for introducing and/or distributing gas in the fermentation liquid; and/or a dynamic movement device located in the loop portion of the reactor, such as a dynamic mixer.

Alternatively or in addition to dynamic mixers, the loop portion may include one or more inactive mixing elements. In one embodiment of the present invention, the one or more inactive mixing elements may be a static mixer.

In one embodiment of the present invention, the loop reactor may include at least one static mixer, at least one dynamic mixer, or include at least one static mixer and at least one dynamic mixer.

In addition to the importance of proper degassing in the overhead reservoir, improving the mass transfer of gaseous substrates to the liquid phase, where the gas becomes available to biocatalysts (eg, methanotrophic organisms) in an energy-efficient manner, may be important.

In addition, as mentioned, it may also be important to improve the waste gaseous removal efficiency by improving the transfer of waste gases from the liquid phase to the gas phase for removal from the fermenter, preferably carried out in the overhead tank.

Preferably, this improved waste gas removal efficiency can be achieved by operating the U-shaped loop portion at elevated pressure and atmospheric pressure or even under vacuum in an overhead tank.

This improved mass transfer in combination with improved gas removal in the overhead vessel can be achieved using a fermentation reactor, a loop reactor according to the invention, which includes a loop portion having a substantially vertical downflow portion, a substantially vertical upflow portion, and a U- a shaped portion having a substantially horizontal connecting portion that connects the lower end of the downflow portion to the lower end of the upflow portion, the upper reservoir may be located above the loop portion and connects the upper end of the downflow portion and the upper end of the upflow portion.

In one embodiment of the present invention, the upper reservoir may have a diameter that is substantially larger than the diameter of the loop portion, the downflow portion, and/or the upflow portion.

In one further embodiment of the present invention, the volume of the loop portion is large, preferably substantially larger, than the volume of the upper reservoir.

In yet another embodiment of the present invention, the upper reservoir may have a diameter that is substantially larger than the diameter of the loop portion, the downflow portion, and/or the upflow portion, and the length of the loop portion may be greater, preferably substantially greater than the length or height of the upper tank.

The fermentation reactor may include liquid circulation means, preferably in the form of a circulation pump.

In one embodiment of the present invention, the fermentation reactor may include an outlet, preferably the outlet may be located in an overhead tank or in a U-shaped loop portion of the fermentation reactor for collecting fermentation liquid.

The fermentation reactor may include one or more gas injection points, which are located in a downflow portion, a U-shaped portion, and/or an upflow portion, as desired and required. Preferably, one or more gas injection points are located in the downflow portion.

Immediately downstream of the one or more gas injection points are at least one active mixing element and/or at least one inactive mixing element for dispersing the gas(es) introduced into the fermentation liquid.

As has been demonstrated, by increasing the pressure in the U-loop, the loop reactor can achieve increased mass transfer from the gas phase to the liquid phase. Thus, a first pressure control device may be inserted into the U-shaped portion of the fermenter to increase the pressure in at least a first zone of the U-shaped portion in the fermenter relative to the pressure in the second zone of the fermenter.

In one preferred embodiment of the present invention, the first pressure control device may be inserted into the upper end of the downflow portion, and the second pressure control device may be inserted into the U-shaped portion of the fermenter and downstream of the first pressure control device at looking in the direction of flow of the fermentation liquid.

The first pressure control device may be a valve (eg, one of the types of valves available commercially), a pump, such as a propeller pump, a vane pump, or a turbine pump, or the pressure may be increased by injection of compressed air or other gas, for example, inert gas. The first pressure control device is preferably a propeller pump, which also circulates liquid in the fermenter.

The second and optionally third pressure control device may be located in the downflow portion, the upflow portion, or the U-shaped portion, but preferably the second pressure control device is located in the upper half portion of the upflow portion. The third optional pressure control device is preferably located in the upper half of the upflow portion and downstream of the second pressure control device when viewed in the direction of flow of the fermentation liquid. The second and/or third pressure control devices are selected from the group of devices including a valve (eg, one of the types of valves available commercially), a static mixer, a hydrocyclone, a pump (eg, a propeller pump, a vane pump, or a turbine pump), a valve pressure controlled, a plate with holes, nozzles or nozzles or a narrowing of the diameter or cross-section of the part of the fermenter in which it is located.

In one embodiment of the present invention, improved gaseous substrate mass transfer can be achieved in the U-shaped portion of the fermentation reactor of the present invention.

In one further embodiment of the present invention, waste gas removal may be provided in the overhead tank of a fermentation reactor in accordance with the present invention.

In one embodiment, the present invention provides means for allowing the headspace to be purged to improve waste gas removal and reduce the risk of explosive gas mixtures forming in the headspace of the fermenter.

This purging can be achieved by providing gas purging means in the upper reservoir, such as devices for adding and/or removing gas in the headspace above the liquid level. The gas purge means may preferably be located above the surface of the liquid to create a gas flow for the purge gas parallel, co-current or counter-current with respect to the flow of liquid at the top of the fermenter. The gas adding means may also be located below the surface of the liquid at the top. Alternatively or additionally, removal of gaseous waste may be increased by reducing the headspace pressure by applying suction or applying a vacuum, thereby reducing the headspace pressure, and/or by installing modification means flow rate at the top. The invention also allows the energy applied to increase the pressure to be recovered for reuse. This can be achieved by coupling a second and optionally third pressure control device to a brake or generator to reduce pressure when using a propeller pump. By connecting the generator to a second and/or third pressure control device, some of the energy applied to the system can be collected, thereby reducing the overall energy consumption of the system.

As used herein, the term "scavenging" is used to refer to a process performed in the overhead tank to remove or assist in the removal of waste gas from the headspace of the overhead tank and/or from the fermentation liquid in the overhead tank.

The overhead reservoir located in accordance with the present invention may be designed to hold from 1% to 99% of the total fermenter volume, but preferably from 10% to 60% of the total fermenter volume, even more preferably 40-50% of the total fermentation volume. In one embodiment of the present invention, the volume of the upper reservoir may be less than the volume of the U-shaped portion.

The upper reservoir may be provided with means to control the flow of liquid or gas to assist mixing in the fermentation reactor or to assist in the release of gas bubbles from the fermentation liquid. The means for regulating the flow of gas or liquid can be dynamic mixers, baffles or static mixers.

The size, that is, both the diameter and the length and/or height, of the loop portion and the size of the upper tank can be varied according to the overall volume requirements of the fermenter.

In one embodiment of the present invention, the fermentation reactor according to the present invention may be equipped with a push gas inlet where the push gas can be introduced to push carbon dioxide in the liquid phase into the exhaust gas separation phase. The propellant gas inlet may preferably be located upstream of the upper reservoir and/or upstream of the first inlet.

A propellant gas, that is, a gas used to displace carbon dioxide from the dissolved phase, (usually nitrogen, but not necessarily another inert non-flammable gas), may, for example, be introduced at one or more points from the beginning of the substantially vertical upflow zone to entering the waste gas removal zone, however, it will be particularly preferably introduced at one or more points between the upper portion (e.g., the top 20%, more preferably the top 10%) of the vertical portion of the upflow zone and the beginning of the flattest (i.e., the most horizontal) section of the zone with outgoing flow.

In the context of the present invention, the term "boost gas" is used to refer to the process carried out in the loop portion, preferably at the upper end of the riser portion, which assists in removing the off-gas from the fermentation liquid into the gas phase.

In one embodiment of the present invention, the fermentation reactor includes both an inlet in the top tank for introducing a purge gas into the top tank and an inlet at the upper end of the riser portion in the loop portion for introducing a push gas to move exhaust gas from the fermentation liquid into gas phase.

One advantage of the present invention may be the ability to provide improved utilization of gaseous materials added to the fermentation reactor.

Therefore, the invention may also relate to a fermentation reactor and fermentation method in the form of a fermentation process, for which at least one of the substrates may be a gas.

The fermentation method may include the steps of adding fermenting microorganisms, essential substrates such as nutrient salts, pH adjusting components and water, and at least one gaseous substrate component such as methane into a loop reactor and fermenting while circulating the fermentation agent. liquid in the loop reactor using means of circulating the liquid, withdrawing the product stream from the fermenter and optionally sending the recovered fermentation liquid (supernatant), if any, for recycling to the loop reactor.

The loop reactor and microbial fermentation method of the present invention may include means for controlling the pressure in the loop reactor.

The fermentation method of the present invention may include the steps of varying the pressure in the circulating fermentation liquid in at least two different zones in the loop reactor by increasing the pressure in at least the first zone of the U-shaped portion or loop portion of the fermentation reactor. reactor relative to the pressure in another zone of the fermentation reactor, thereby increasing the mass transfer of at least one added gaseous substrate component, such as methane, from the gas phase to the liquid phase in that zone, followed by a subsequent decrease in pressure in the other zone in relation to the pressure in the first zone until the circulating fermentation liquid enters the upper part of the reactor, which initiates the release of gases such as off-gases like CO ₂ from the liquid phase, and the release of gases trapped in the circulating fermentation liquid in the upper tank of the fermentation reactor .

The performance of the fermentation reactor and/or fermentation process according to the present invention can be further optimized in the sense that the circulating fermentation liquid is subject to variable pressure during circulation in the fermenter and is characterized by increased mass transfer and solubility of substrate gases in the liquid phase in a zone characterized by increased pressure. Productivity can also be improved as a result of the release of gases, such as waste gases, from the circulating fermentation liquid, where this release is increased in areas where pressure is reduced.

The fermentation reactor and/or fermentation method according to the present invention can be further improved by providing a third zone between the second pressure control device and the third pressure control device and differently controlling the pressure in the circulating fermentation liquid in each of the three different zones - the first zone, second zone and third zone. This pressure control in the third zone can be achieved by increasing the pressure in the first zone using the first pressure control device and decreasing the pressure in the subsequent two zones (the second zone and the third zone) in two stages using the second and third control devices pressure.

In one embodiment of the present invention, increased pressure in the loop portion of the fermentation reactor in the first zone and/or between the first pressure control device and the second pressure control device can be obtained by applying a pressure greater than 0.5 bar above atmospheric pressure; thus, as pressures more than 1 bar above atmospheric pressure; for example, pressures more than 1.5 bar above atmospheric pressure; thus, as pressures more than 2 bar above atmospheric pressure; for example, pressures greater than 2.5 bar above atmospheric pressure; thus, as pressures more than 3 bar above atmospheric pressure; for example, pressures greater than 3.5 bar above atmospheric pressure; thus, as pressures more than 4 bar above atmospheric pressure; for example, pressures greater than 4.5 bar above atmospheric pressure; thus, as pressures more than 5 bar above atmospheric pressure; for example, pressures greater than 5.5 bar above atmospheric pressure; thus, as pressures more than 6 bar above atmospheric pressure; for example, pressures more than 7 bar above atmospheric pressure.

In yet another embodiment of the present invention, increased pressure in the loop portion of the fermentation reactor, in the first zone and/or between the first pressure control device and the second pressure control device can be obtained by applying a pressure in the range of 0.5-10 bar above atmospheric pressure; thus, as pressures in the range of 1-9 bar above atmospheric pressure; for example, pressures more than 1.5-8 bar above atmospheric pressure; thus, as pressures in the range of 2-7 bar above atmospheric pressure; for example, pressures more than 3-6 bar above atmospheric pressure; thus, as pressures in the range of 4-5 bar above atmospheric pressure.

In yet another further embodiment of the present invention, the pressure in the upper reservoir may be less than 0.5 bar above atmospheric pressure; thus as 0.25 bar above atmospheric pressure; thus as 0.1 bar above atmospheric pressure; thus, as approximately atmospheric pressure; for example, less than 0.75 bar below atmospheric pressure; thus as 0.5 bar below atmospheric pressure; for example, less than 0.25 bar below atmospheric pressure; thus as 0.1 bar below atmospheric pressure.

The first pressure control device may preferably be a pump, for example a propeller pump, a vane pump or a turbine pump, particularly designed for circulating a gas-liquid mixture. Other suitable means of increasing the pressure and circulating the liquid in the fermenter are, for example, the addition of a compressed gas, such as air or an inert gas, in combination with a liquid circulating device, which may be a pump.

The second pressure control device according to the present invention may be selected from pressure control devices such as: a reduction in the diameter/cross-section of the upflow portion or a U-shaped portion, a plate with holes, nozzles or nozzles inserted into the upflow portion. an upflow or U-piece, a valve such as a pressure controlled valve at one or more locations in the fermenter, a static mixer, a hydrocyclone or a pump such as a propeller pump, vane pump or turbine pump.

As mentioned before, gas separation for waste gases in the fermenter can be improved by adding a means of purging the headspace and/or fermentation liquid in the overhead tank. This can be achieved by creating a purge gas flow to purge the free space above the liquid level in parallel, co-current or counter-current with respect to the liquid flow at the top. Gas separation can also be further improved by adding a purge gas (eg, air, CO ₂ or inert gas, or mixtures thereof) to the top reservoir below the liquid surface to increase the desorption of gases from the fermentation liquid in the top reservoir into the headspace above the liquid level. This can also be achieved by passing the fermentation liquid through a flow control means in the upper tank.

In one embodiment of the present invention, the fermentation reactor and method of the present invention are designed for methanotrophic fermentation.

In one additional embodiment of the present invention, the fermentation reactor may be designed for fermentation with methanotrophic organisms.

In one embodiment of the present invention, the gaseous substrate supplied during fermentation in methanotrophic organisms may contain an alkane. Preferably the alkane is a C1 compound. In one preferred embodiment of the present invention, the alkane may preferably be a C1 compound and/or a C1 alkane. Preferably, the C1 compound and/or C1 alkane may be methane, methanol, natural gas, biogas, synthesis gas, or any combination thereof. Even more preferably, the C1 compound and/or the C1 alkane may be methane.

The methanotrophic organisms may preferably be methanotrophic bacteria such as Methylococcus Capsulatus.

Methanotrophic bacteria may be present during co-fermentation with one or more heterotrophic bacteria.

The following heterotrophic bacteria may be particularly suitable for use in co-fermentation with M. capsulatus organisms; Ralstonia sp. ; Bacillus brevis ; Brevibacillus agri ; Alcaligenes acidovorans ; Aneurinibacillus danicus and Bacillus firmus . Suitable yeasts to be used may be selected from Saccharomyces and/or Candida species.

Preferred heterotrophic bacteria are selected from the organisms Alcaligenes acidovorans (NCIMB 13287), Aneurinibacillus danicus (NCIMB 13288) and Bacillus firmus (NCIMB 13289) and combinations thereof.

In one embodiment of the present invention, the methanotrophic organism may be a genetically modified methanotrophic organism, and/or the heterotrophic organism may be a genetically modified heterotrophic organism.

The fermentation reactor and/or fermentation process of the present invention may be particularly relevant to the production of single cell organism (SBO) protein through continuous fermentation processes in crops such as Methylococcus capsulatus.

Preferred methanotrophic bacteria are species from the family Methylococcus, especially Methylococcus capsulatus, which use methane or methanol as a carbon source and ammonia, nitrate or molecular nitrogen as a nitrogen source for protein synthesis.

Additional details regarding suitable modifications of the loop reactor and the nature of the operation of such a loop reactor and processing of the resulting biomass may be consistent with the disclosures in WO 2010/069313; WO 2000/70014; WO 2003/016460; WO 2018/158319; WO 2018/158322; WO 2018/115042 and WO 2017/080987, all of which are incorporated herein by reference.

The first embodiment of the present invention relates to a loop reactor; preferably a U-shaped loop reactor, where the loop reactor includes a loop portion. The loop portion includes a loop portion downflow portion, a U-shaped portion, an upflow portion, and an upper reservoir. The upper reservoir includes a vent pipe for discharging the gas or gases separated in the headspace above the liquid level of the upper reservoir and also referred to as "vent gas". Along the loop portion of the fermentation reactor, the loop reactor, elements are arranged for introducing a gas, for example, a gaseous substrate like methane, ammonia, atmospheric air, pure oxygen, or atmospheric air enriched in pure oxygen, into the fermentation reactor. Preferably, the gas introduction elements are located in the loop portion of the loop reactor, even more preferably, the gas introduction elements are located in the downflow portion and/or the upflow portion of the loop reactor. The fermentation reactor (loop reactor) can be equipped with a pump for circulating the fermentation liquid (circulation pump) in the loop reactor. In one embodiment of the present invention, a circulation pump may be installed in the U-shaped portion of the fermentation reactor to circulate the broth in the fermenter. This circulation pump may alternatively and preferably be located at the top of the downflow portion, for example serving as a first pressure control device. Throughout the downflow portion and/or upflow portion, dynamic mixers or a static mechanical mixing element ensure that the feed gases are dispersed to produce numerous small, fine bubbles in the fermentation liquid. Supply channels may be provided for the addition of water and nutrient salts such as phosphate, ammonium, magnesium, calcium, potassium, iron, copper, zinc, manganese, nickel, cobalt and molybdenum in the form of sulfates, chlorides or nitrates, phosphates, and components for control the pH value, preferably the feed channels are located in the downflow part and/or in the upflow part, preferably the feed channels are located in the downflow part. The fermentation reactor (loop reactor) may be provided with an outlet for decanting fermentation liquid, characterized by levels of produced biomass and/or other product substances, for downstream processing. The outlet may be located in the U-shaped portion and/or in the upper reservoir. The loop reactor (fermentation reactor) can also be equipped with one or more sensors. The sensors may be arranged to sense or determine concentrations of gases and/or ions of interest, for example, CH ₄ and O ₂ , and/or at least one of phosphate, ammonium, nitrate, nitrite and hydrogen ions (pH), may be one or more thermal sensors are provided for sensing the temperature of the fermentation liquid in the loop portion and/or a foam sensor for sensing the development of excess foam in the upper tank.

The sensors can deliver signals to a data processing (PC) system (not demonstrated), which can control the entire fermentation process, including downstream processing equipment.

In order to control foaming and/or turbulence in the fermentation liquid in the upper tank to ensure optimized off-gas degassing and thus improved fermentation process performance, the upper tank of the loop reactor (fermentation reactor) may be equipped with a visual monitoring means. Preferably, the visual observation means may be positioned to provide a horizontal or substantially horizontal field of view. The visual observation means may be located on the side of the upper tank, allowing a combined view above the surface of the fermentation liquid and below the surface of the fermentation liquid. Preferably, the visual observation means may be located at the end of the upper reservoir. Preferably, the viewing means may be located at the end of the upper reservoir, providing a view from the first inlet (or upflow portion) to the first outlet (or downflow portion). The visual observation means may be a viewing hole, a camera, or a combination of a viewing hole and a camera. In one embodiment of the present invention, the viewing hole may be a sight glass. In yet another embodiment of the present invention, the camera may be an in-line camera.

One example of downstream processing suitable for use on the resulting biomass to produce various fractions may be as described in WO 2018/115042.

A second embodiment of the present invention relates to a loop reactor (fermentation reactor) similar to the first embodiment described above, in which the pressure can be increased in specific areas of the loop reactor while the pressure is substantially equal to atmospheric pressure, or in other areas of the loop reactor, for example in the upper tank, a pressure may be obtained, optionally reduced below atmospheric pressure.

In order to control the pressure in specific zones of the loop reactor (fermentation reactor), one or more pressure control devices may be located in the loop reactor to control the pressure in the fermenter so that different zones of the fermenter experience more or less pressure than other zones. , for example, the loop part of a loop reactor.

In one embodiment of the present invention, the devices used to control the pressure are also used to circulate the liquid and/or gas-liquid mixture in the fermenter, that is, a circulation pump.

In one preferred embodiment of the invention, the first pressure control device may be located in the upper region of the downdraft part or in the connecting parts between the upper reservoir and the downdraft part, for example in their lower part. The first pressure control device may preferentially circulate liquid in the fermenter and at the same time encourage an increase in pressure as the liquid or gas-liquid mixture passes through the first pressure control device. The first pressure control device may preferably be a pump, for example a circulation pump, a propeller pump, a vane pump or a turbine pump, particularly designed for circulating a gas-liquid mixture. Other suitable means of increasing the pressure and circulating the liquid in the fermenter are, for example, adding compressed gas to increase the pressure rather than simply introducing nutrients or ingredients into the fermentation liquid. When the first pressure control device may be a pump, such as a propeller pump, the pump, such as a propeller pump, may be driven by use of a motor.

The second pressure control device may be located in the loop reactor (fermentation reactor), preferably in the loop part, for example, in one part selected from the downflow part or the upflow part or in the horizontal part of the U-shaped part of the loop reactor (fermentation reactor). reactor). Preferably, the second pressure control device may be located in the upflow portion of the fermentation reactor such that the pressure can be increased between the first pressure control device and the second pressure control device when viewed in the direction of flow.

As the pressure in a particular zone in the fermenter increases, the solubility of the injected gases in the liquid phase also increases. In one preferred embodiment, the second pressure control device may be positioned midway up to the top region of the upflow portion of the fermentation reactor (or loop portion).

The second pressure control device may be selected from among pressure control devices such as: a reduction in diameter/cross section of the upflow or U-shaped portion, a plate with holes, nozzles or nozzles inserted into the upflow or U-shaped portion a shaped portion, a valve, such as a pressure-controlled valve at one or more locations in the fermenter, a static mixer, a hydrocyclone, or a pump such as a propeller pump, vane pump, or turbine pump.

The loop reactor (fermentation reactor) may be equipped with one or more pressure sensing devices. One or more pressure sensing devices may be located throughout the loop reactor, such as in the upper reservoir and/or in the loop portion. Preferably, at least one pressure sensor may be located in each of the zones of the fermenter operating at different pressures. The pressure sensing devices may be coupled to a process control system, such as a computer, which can control the pressure control devices to maintain optimal pressure in each of the zones of the fermentation reactor.

With respect to both the first and second embodiments, in accordance with the above description of the invention, the loop fermenter (fermentation reactor) according to the present invention may further include one or more sensors for determining dissolved oxygen (DO), which may also be located in the fermenter for the purpose of detecting that the oxygen level in the fermenter is maintained within a predetermined range, which depends on the microorganism or microorganisms used in the fermentation.

Additional sensors can be located in the fermentation reactor, in the upper tank and/or in the U-shaped part, for example, to measure temperature, pH value, conductivity, redox potential and various ions present in the broth, for example, ammonium, nitrite , nitrate, phosphates and the like.

Sensors may include biosensors, electrochemical sensors such as ion selective electrodes, or sensors based on FIA (flow injection analysis) and optical measurements such as spectrophotometric devices. A near-infrared (NIR) probe can also be used to measure several different components in the broth or cells in the fermenter, such as the concentration of cells, amino acids, methanol, ethanol and/or other ions. The fermentation reactor may be equipped with a mass spectrometry (MS) sensor or an electronic odor analyzer to determine the concentration of gaseous and volatile components (eg, CO ₂ and/or CH ₄ ) in the headspace above the liquid level. An MS sensor or electronic odor analyzer may control the pressure applied in the fermenter and/or the addition of gaseous components, such as methane and/or air/oxygen, and/or the addition of ammonia gas or ammonia/ammonium in solution. A high-speed camera may be installed in the U-shaped portion of the fermentation reactor, preferably in connection with the gas injection, to determine the size of gas bubbles in the broth. The size of the bubbles can be determined by image processing of data from a high-speed camera.

Recycle supernatant may also be added to the top of the fermenter, alternatively it may be added at one or more positions in the U-shaped portion of the fermentation reactor. Returning supernatant from downstream processing can reduce the overall consumption of substrates, carbon and minerals, thereby reducing fermentation process costs.

The connecting parts may or may not include anti-vortex means (not shown), such as baffles and the like, as required.

The fermentation reactor according to the present invention can generally be operated in continuous operation after cleaning and sterilization techniques are implemented, followed by a start-up period during which water, necessary nutrient salts and microorganisms are added to the fermentation reactor. The fermentation liquid can be circulated in the fermentation reactor, mainly by using the first pressure control device. After this, the addition of gaseous substrates can be initiated and fermentation can begin. When the microbial density reaches a concentration of approximately 0.5-10%, and preferably 1-5%, (on a dry weight basis), the fermentation liquid can be continuously withdrawn from the fermentation reactor, for example from the overhead tank or from the U-shaped part, and subjected to downstream processing, for example, in accordance with the description of the invention in publication WO 2018/115042.

The withdrawal of fermentation liquid can be initiated simultaneously with the addition of make-up water, aqueous substrate and/or recirculation of the supernatant at a degree of dilution depending on the microorganisms used in the fermentation. The addition of substrate components in liquid solution, additional water, recirculation of the supernatant as feed for the selected broth and gaseous substrates can be controlled using a computer receiving data from gas sensors and suitable for the use of calculations to obtain the required quantities of each component to obtain optimized growth of organisms .

It should be noted that embodiments and features described in the context of one aspect of the present invention also apply to other aspects of the invention.

All patent and non-patent references cited in this application are hereby incorporated by reference in their entirety.

Literary references

WO 2010/069313

WO 2000/70014

WO 2003/016460

WO 2018/158319

WO 2018/158322

WO 2018/115042

WO 2017/080987

WO 2018/132379

Claims (11)

1. A fermentation reactor including a loop portion and an upper reservoir, wherein said loop portion includes a downflow portion connected to an upflow portion through a U-shaped portion, wherein the upper reservoir includes: (i) a first outlet connecting the upper reservoir to the downflow portion of the loop portion and allowing the fermentation liquid present in the upper reservoir to flow from the upper reservoir to the loop portion; (ii) a first inlet connecting the upper reservoir to the upflow portion of the loop portion and allowing the fermentation liquid present in the loop portion to flow from the loop portion to the upper reservoir; And (iii) a vent pipe to discharge waste gases from the upper tank; wherein the upper reservoir further includes a visual observation means located at an end of the upper reservoir providing a view from the first inlet to the first outlet with a substantially horizontal field of view. 2. The fermentation reactor according to claim 1, wherein the visual observation means is located on a side of the upper tank providing a combined view above the surface of the fermentation liquid and below the surface of the fermentation liquid. 3. The fermentation reactor according to any one of the preceding claims, wherein the visual observation means is a viewing hole, a viewing camera, or a combination of a viewing hole and a recording camera. 4. The fermentation reactor according to claim 3, in which the inspection hole is a sight glass. 5. The fermentation reactor according to any one of the preceding claims, wherein the upper tank is equipped with a foam sensor inside the upper tank. 6. The fermentation reactor according to any one of the preceding claims, wherein the fermentation reactor is designed for fermentation with methanotrophic organisms. 7. The fermentation reactor according to any one of the preceding claims, wherein the loop portion of the fermentation reactor includes one or more active devices and/or one or more inactive mixing elements for distributing gas in the fermentation liquid.

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