EP3365423A1

EP3365423A1 - Liquid-medium digester with gas-flow-based agitation, comprising an automatic device for establishing a fluid communication between the upflow and downflow spaces according to the height of the medium

Info

Publication number: EP3365423A1
Application number: EP16791661.8A
Authority: EP
Inventors: Arnaud CHEYROU LAGREZE; Philippe BAILLON; Stephane FAY
Original assignee: Gg Coriolis
Current assignee: BIOREA
Priority date: 2015-10-23
Filing date: 2016-10-14
Publication date: 2018-08-29
Also published as: IL257992A; IL257992B; FR3042795A1; JP2018531047A; KR20180072756A; WO2017068265A1; US10975347B2; KR102625786B1; FR3042795B1; JP6770670B2; CN108138107B; CN108138107A; US20180305653A1

Abstract

The invention relates to a digester for a liquid medium, comprising a container, a dividing wall between two spaces, and a device for injecting gas into the lower part of one of the spaces. The gas creates an upflow of the mixture of liquid medium and injected gas in said space, and a downflow in the other space. The dividing wall is equipped with at least one device for establishing a fluid communication between the spaces, so that the fluid communication configuration is automatically varied between a first open configuration in which fluid can flow freely from one space to the other, and a second closed configuration in which the flow of fluid is blocked fully or partially by the aforementioned device.

Description

Fermenter for a liquid medium with agitation by circulating a gas, comprising an automatic device for placing in fluid communication between the volumes with ascending and descending circulation as a function of the height of the medium

The present invention relates to a fermentor for liquid medium for continuous or discontinuous production, comprising means for stirring by circulation of a gas, the fermenter comprising:

a container adapted to contain the liquid medium,

a separating wall positioned in the receptacle and separating first and second volumes,

a device for injecting this gas into the lower part of one of the first or second volumes to create in this volume an upward circulation of the mixture between the liquid medium and the injected gas and a downward circulation of this mixture in the volume supplied with gas by the injection device.

In known manner, a fermenter is an apparatus in which a fermentation of the liquid medium is carried out. This device, also known as a bioreactor or propagator, allows the multiplication of microorganisms (yeasts, bacteria, microscopic fungi, algae, animal and plant cells). It makes it possible to control the cultivation conditions such as temperature, pH or gasification, conferring a high reliability of the harvested information.

Two categories of solutions conventionally exist for agitating the liquid medium during the fermentation process.

The first category of solutions for agitating the liquid medium, the most used, exploits motorized means which impose a circulation of the liquid medium, for example using one or more motor (s), in particular via mechanized agitators.

This solution has the advantage of being able to operate at varying levels of liquid medium inside the container. In case of foaming or uncontrolled evaporation of the liquid medium, it is always agitated, to avoid a stop or a sharp reduction in gas exchange. However, this solution has the disadvantage of being complex and expensive. It calls for the use of motorized systems and means of sealing associated with these engines, which involves adding parts, and requires human intervention.

A second category of solutions for agitating the liquid medium provides for the use of agitation means by circulating a gas injected into the lower part of the liquid medium, this technology being conventionally known in the English terminology "air lift". The invention which will be described concerns a solution falling within this second category.

This solution has the advantage of not using a mechanical system as previously described. But this solution generally requires a constant level operation of the liquid medium in the container. The foam and evaporation phenomena are therefore very problematic because, in the event of a drop in the level of liquid medium in the container, there is a risk of poor downward circulation and the gasification is no longer effective in a large part of the fermenter . Agitation and gas exchange will decrease dramatically in this part of the fermenter. Micro-organisms may die and sediment.

Conventionally, a fermenter with "air lift" technology comprises a container containing the liquid medium and at least one partition wall, for example constituted in an inner tube, positioned in the container to delimit on either side thereof a first volume and a second volume. A gas injection device is arranged in the lower part of one of these two volumes to create an upward circulation of the mixture between the liquid medium and the gas injected into this volume and a downward circulation of this mixture in the non-liquid volume. supplied with gas by the injection device.

Regardless of the height of the inner tube, the system is likely to defuse as soon as the liquid medium is in static equilibrium at a given level below the discharge zone.

In order to limit as much as possible the risks of the circulation in the fermenter being defused in the event of a drop in the level of liquid medium, especially in the case of foaming or uncontrolled evaporation, there are solutions where the inner tube comprises openings and means for closing these manually controlled openings, in the image of the solution described in the document US3236744A1. But this solution is based on the human factor and is unreliable, it would also be possible to provide an inner tube having a variable height depending on the level of the liquid medium but this solution would not be easily achievable. The present invention aims to solve all or part of the disadvantages listed above.

In this context, there is a need to provide a fermentor for a liquid medium agitated by circulation of a gas, that is to say that corresponds to the second category of solutions mentioned above, which allows:

to be simple, reliable and economical,

to avoid the risks of external contamination, in particular inherent to the sealing means of the axis passages or actuators coming from outside the fermenter,

to guarantee agitation and gas exchange whatever the level of the liquid medium,

to avoid the risks of malfunction of the fermenter and sedimentation of the micro-organisms,

- avoid the use of motorized systems and limit human intervention,

- To reduce the use of opening / closing means and sealing means. These objects can be reached by a fermenter according to the appended claims.

In particular, to meet the problems listed above, there is provided a fermenter for a liquid medium, comprising means for stirring by circulation of a gas, comprising a container adapted to contain the liquid medium, a partition wall positioned in the container and separating first and second volumes, a device for injecting said gas into the lower part of one of the first or second volumes to create in said volume an upward circulation of the mixture between the liquid medium and the injected gas and a downward circulation of said mixture in the volume not supplied with gas by said injection device, the partition wall being equipped with at least one device for fluid communication of the first and second volumes between them configured so as to automatically vary between:

a first configuration in which the device for fluidic communication allows, for the liquid medium and the gas contained in the container, a free fluid flow from one volume to the other through said device for putting in fluid communication, the first configuration being occupied as soon as at the level of the fluidic communication device, the difference between the pressure of said mixture in the volume where the upward circulation occurs and the pressure of said mixture in the volume where the downward circulation occurs is greater than a predetermined threshold value,

and a second configuration in which the fluidic communication device blocks all or part of said fluid circulation for the liquid medium and the gas contained in the container, the second configuration being occupied as soon as at the level of the device for fluid communication the difference between the pressure of said mixture in the volume where the upward circulation occurs and the pressure of said mixture in the volume where the downward circulation occurs is less than or equal to the predetermined threshold value.

The invention will be better understood from the following description of particular embodiments of the invention given by way of non-limiting example and shown in the accompanying drawings, in which:

FIG. 1 is a view, in perspective and in transparency, of an example of a fermenter according to the invention,

FIG. 2 is a perspective view of a closure element and the corresponding connecting mechanism used in the fermenter of FIG. 1,

Figure 3 is a perspective view of the closure member and the support arm shown in Figure 2;

FIG. 4A is a partial view, in perspective and in transparency, of the fermenter of FIG. 1, representing a plurality of communication devices, each occupying its first configuration,

Figure 4B shows in detail the area marked A in Figure 4A,

And FIGS. 5 and 6 schematically represent a fermenter according to the invention, in longitudinal section, respectively in the second configuration and in the first configuration.

With reference to the appended figures as summarily presented above, the invention essentially relates to a fermentor 10 for a liquid medium ensuring a continuous or discontinuous production. The fermenter comprises means ensuring agitation of the liquid medium by circulating a gas in the liquid medium. The liquid medium may be a sterile medium or a medium with controlled contamination. The fermenter 10 is therefore of the type corresponding to the technology "air lift" in English terminology. The fermenter 10 is generally configured so as to ensure fermentation of the liquid medium. This device, also known as a bioreactor or propagator, allows the multiplication of microorganisms (yeasts, bacteria, microscopic fungi, algae, animal and plant cells). It makes it possible to control the cultivation conditions such as temperature, pH, gasification or gas exchange, thus conferring a high degree of reliability on the information collected.

In general, the fermenter 10 which will be described in detail below comprises:

a container 11 adapted to contain the liquid medium, its shape possibly being any,

a separation wall positioned in the container 11 and separating first and second volumes VI, V2 inside the container 11,

a device 13 for injecting the gas mentioned above, configured so as to inject it into the lower part of the first volume VI or the second volume V2 in order to create, in this volume where the injection takes place, an upward circulation of the mixing between the liquid medium and the injected gas, and a downward circulation of this mixture in the other volume, that is to say in the volume not supplied with gas by the injection device 13.

The nature, constitution or shape of the partition wall, which has a height marked H, can be any. In the illustrated example, the partition wall is formed in an inner tube 12 positioned in the container 11 in such a way that the inner tube 12 internally delimits the first volume VI and outwardly delimits the second volume V2 in combination with the container 11. In other words, in this particular example, the first volume VI corresponds to the internal volume delimited by the inner tube 12 while the second volume V2 is located around the inner tube 12, between the latter and the walls of the container 11.

But it goes without saying that this construction of the partition wall in the form of a single inner tube 12 is not limiting. In particular, it is for example possible to provide several concentric tubes having sections of any shape, or parallel compartments in a container 11 of any shape, for example rectangular.

In the variant shown and in a nonlimiting manner, the injection device 13 injects the gas into the lower part of the first volume VI, so that the upward circulation of the mixture between the liquid medium and the injected gas is produced in the first volume VI, that is to say inside the inner tube 12, here circular section. The downward circulation of this mixture then occurs in the second volume V2, that is to say in the intermediate volume, here of annular section, between the inner wall of the container 11 and the outer wall of the inner tube 12.

However, it is quite possible to envisage an inverted configuration in which the injection device 13 injects the gas into the lower part of the second volume V2 so that the upward circulation of the mixture between the liquid medium and the injected gas occurs. in the second volume V2 between the container 11 and the inner tube 12. In this alternative, the downward circulation would then occur in the first volume VI, inside the inner tube 12.

In the figures, it can be seen that the container 11 of the fermenter 10 comprises an inlet 14 for feeding the container 11, and therefore the fermenter 10, in a liquid medium to be fermented and an outlet 15 for discharging the liquid medium out of the container 11 after fermentation , and therefore out of the fermenter 10. The inlet 14 and the outlet 15 can be equipped with all the conventional means known in the technical field concerned, for example to regulate the flow of liquid medium entering the fermenter 10 via the inlet 14 and / or leaving the fermenter 10 at the outlet 15. In general, the fermenter 10 can be equipped with all the means conventionally used in the technical field of fermenters, especially any sensor or equivalent for determining a physical characteristic of the medium liquid or mixture in this zone, such as temperature, pressure, flow, level, a foam sensor element etc. The ferm also includes an inlet 23 for supplying the gas to the injection device 13 and a drainage system 24.

The partition wall is equipped with at least one fluid communication setting device 16 selectively enabling the first and second volumes VI, V2 to be in fluid communication with each other. Each device for setting fluid communication 16 is in particular configured so as to vary automatically, without any human intervention for this purpose, between:

a first configuration (FIG. 6) in which the fluidic communication device 16 allows, for the liquid medium and the gas contained in the container 11, a free fluid flow from one volume to the other through said device setting into fluid communication 16, and a second configuration (FIG. 5) in which the fluidic communication device 16 blocks all or part of this fluid circulation for the liquid medium and the gas contained in the container 11.

Advantageously, said at least one fluid communication setting device 16 is automatic in a manner requiring no manual intervention, operating autonomously, which allows a reliable and efficient circulation and therefore an optimal stirring.

The first configuration is occupied as soon as at the level of the fluid communication device 16, at least one physical parameter of the mixture satisfies a predetermined condition. The second configuration is occupied as soon as at the level of the fluid communication device 16, said at least one physical parameter does not satisfy the predetermined condition mentioned above.

Said at least one physical parameter comprises the value of the pressure of the mixture respectively in the first and second volumes VI and V2. The first configuration is occupied as soon as the difference between the pressure in the volume where the upward circulation occurs and the pressure in the volume where the downward circulation occurs is greater than a value at the level of the fluid communication device 16. predetermined threshold. This situation can occur when the liquid medium in the volume where the ascending circulation occurs no longer communicates with the volume where the downward circulation occurs, because of a difference in levels no longer allowing the liquid medium to overflow from the volume to the volume. upward movement to downflow volume. The second configuration is, on the contrary, occupied as soon as the difference between the pressure in the volume where the ascending circulation occurs and the pressure in the volume where the downward circulation occurs is lower than the level of the fluidic communication device 16. equal to the above-mentioned predetermined threshold value.

It is clear that the pressure difference between the upflow and downflow volumes can quite be induced by a difference in levels of the liquid medium in these two volumes respectively. By way of example, if the level of the liquid medium in the downflow volume is lower than the level of the liquid medium in the upflow volume, the pressure differential is reversed with respect to the normal state of the fermenter 10. continuous diet; in fact, the pressure of the liquid medium in the upflow volume becomes greater than the pressure of the liquid medium in the downflow volume. The predetermined threshold value beyond which the first configuration is automatically applied may be equal to 0 (the second configuration then being automatically adopted in the event of equal pressure between the volumes VI and V2 at the device 16) or adopt a constant value greater than 0 and fixed by a suitable mechanical member, such as a spring or the like.

FIGS. 1, 4A and 4B show the fermenter 10 in the hypothetical situation where each fluid communication device 16 adopts its first configuration, for reasons of comprehension only. In use, it goes without saying that each fluidic communication device 16 adopts its second configuration when it is not immersed in the liquid medium or when the pressure difference between the two volumes is not sufficient. to override the threshold value.

According to a particular embodiment, the fermenter 10 comprises a plurality of separate fluid communication devices 16 and arranged in different zones of the partition wall staggered along its height H. In other words, the devices for setting fluid communication 16 are arranged in different areas of the inner tube 12 spaced over its height. It is specified that the inner tube 12 is oriented vertically so that its height corresponds to the direction in which the level of liquid medium varies within the container 11. In the particular example illustrated in Figures 1, 2, 3, 4a and 4B, the fermenter 10 comprises three separate fluid communication devices 16 staggered along the height of the inner tube 12. In FIGS. 5 and 6, the fermenter 10 comprises only two separate fluid communication devices staggered along the length of the inner tube 12. In FIGS. the height of the inner tube 12: there is arranged an upper fluidic communication device 16 16 and a lower 16 fluid communication device 16, independent of one another. It goes without saying that the number of fluid communication devices 16 may be arbitrary, depending for example on the height H of the partition, the required accuracy, the nature of the liquid medium, etc. setting fluid communication 16 may be distributed over all or part of the height H of the partition wall, at a regular pitch or not.

In FIG. 6, only the upper fluidic communication device 16 occupies its first configuration while, at the same time, the lower fluidic communication device 16 is in the second configuration. In FIG. 5, the upper fluid communication device 16 and the lower fluid communication device 16 are both in their second configurations.

The fermenter 10 makes it possible to solve the problems posed by the fermentors of the prior art. In a normal operating condition of the fermenter 10, which is shown in FIG. 5, each fluid communication device 16 is in its second configuration. This is why in FIG. 5, the upper fluidic communication device 16 is in its second configuration and the lower fluid communication device 16 is also in its second configuration. Each fluidic communication device 16 is therefore normally closed in the normal situation of the fermenter 10 and blocks the circulation from one volume to another, especially when the level NI of liquid medium in the fermenter 10 remains generally constant (the pressures in the volumes VI, V2 on either side of each device being substantially identical). The direction of upward movement in the first volume VI is indicated by the arrows F1. The downward flow direction inside the second volume V2 is symbolized by the arrows F3. In the upper part of the fermenter 10, from the top of the partition wall, the discharge of the liquid medium from the upflow volume to the downflow volume is represented by the arrows F2. In the lower part of the fermenter 10, from below the separation wall, the return of the liquid medium to pass from the downflow volume to the upflow volume is shown schematically by the arrows F4.

FIG. 6 shows, on the other hand, a situation of the fermenter 10 in which one of the fluid communication communication devices 16 automatically and autonomously occupies its first configuration. The arrows F1, F3 and F4 are always illustrated to show that in these zones, the manner of circulation of the liquid medium is identical to that of FIG. 5. But in FIG. 6 the arrows F2 are absent because the liquid medium spill does not occur. is more than one volume to another above the partition wall. On the contrary, when the level of liquid medium tends to fall in the fermenter 10, for example in the case of foaming or uncontrolled evaporation, the pressure in the volume with upward circulation (here in volume VI) tends to increase. relative to the pressure in the downflow volume (here in volume V2). In FIG. 6, the level of the liquid medium in the fermenter 10 has decreased overall in comparison with the NI level initially occupied in the normal situation of FIG. of liquid medium in the upflow volume is denoted N2 and the level of liquid medium in the downflow volume is denoted N3, the levels N2 and N3 thus being located below the NI level, for example due to evaporation. or uncontrolled foaming. On the other hand, because of the pressure differences in the two volumes, the N3 level is below the N2 level. The difference in pressures in volumes VI and V2 which is concomitant with the difference between the levels N2 and N3 in volumes VI and V2 can increase to become, at least in certain areas of the height H of the partition wall ( which here corresponds to the height of the inner tube 12), greater than the predetermined threshold value associated with the differential pressure. In these areas where the threshold value is exceeded, the fluid communication setting device 16 subjected to this differential pressure automatically automatically occupy the first configuration under the effect of this pressure difference. This is the reason why, in FIG. 6, the upper fluidic communication device 16 automatically occupies its first configuration. On the other hand, FIG. 6 shows the particular case where the pressure difference in the volumes VI and V2 is not sufficient to exceed the predetermined threshold value: the lower fluidic communication device therefore remains in its second configuration, at the opposite of the device for placing in fluidic communication 16 higher. It is quite clear that the fluidic communication devices 16 of the same fermenter 10 are independent and autonomous from each other, each operating automatically without any external action other than the actions of the pressure differentials in the two volumes on the one hand. and other devices for placing in fluid communication 16.

In FIG. 6, the passage of the upper fluid communication device 16 towards its first configuration promotes a return to the initial pressures (when the NI level was established) in the two volumes VI, V2. Such a change to the first configuration allows the liquid medium and the injected gas to flow freely through the upper fluidic communication device 16 thus open, especially in one direction (shown schematically by the arrows F5) from the volume where the upward movement towards the volume where the downward circulation takes place. This temporary, free and automatic circulation of the liquid medium through the upper fluidic communication device 16 has the effect of compensating for and correcting the consequences of the lowering of the level of the liquid medium in the fermenter 10. Thus the circulation at the The interior of the fermenter 10 does not stop. This makes it possible to avoid a blocking of the fermenter 10 and a risk of dead zone devoid of circulation and gaseous exchange, which would otherwise lead to a cessation of fermentation or even a change in conditions of the liquid medium, likely to cause death of microorganisms. Then, when the liquid medium level is increased and the spill resumes at the top of the separation wall, the pressure in the upflow volume decreases as the pressure increases in the downflow volume. The upper fluidic communication device 16 then automatically returns to its second configuration. In the illustrated example, the liquid medium has a tendency to flow from the first volume VI to the second volume V2 in the first configuration of each fluid communication device 16. When the liquid medium level is allowed to increase sufficiently in the fermenter 10, it causes again a depression in the upflow volume and an overpressure in the volume downflow sufficient to automatically cause the return to the second configuration of the device in fluid communication concerned.

The arrangement of several fluidic communication devices 16 at different heights has the advantage of automatically and autonomously compensating for changes in the height of the liquid medium, in particular in a situation of foaming and uncontrolled evaporation, and of limiting the risks of blocking fermentor 10 and stopping fermentation or death of microorganisms (this allows to maintain a liquid culture medium at the same physicochemical conditions). The fermenter 10, in addition to being very simple in design and very economical compared to the fermenters of the prior art according to the first category, is therefore very reliable and secure. It has the advantage of not requiring motorized systems, and to overcome a need for opening and closing means actuated from the outside and therefore to sealing means. It avoids the need for human intervention and the risk of external contamination.

The fermenter 10 having this characteristic has the additional advantage of being able to operate even better with varying levels of liquid medium inside the container 11, without having to provide a height of the inner tube 12 that is weak or variable or to use motorized stirring systems of the liquid medium. This makes it possible to open or close the fluidic communication setting devices 16 at different levels depending on the height of the liquid medium in the volume supplied with gas.

Preferably, each device for setting fluid communication 16 is autonomous and varies from one configuration to another without external action and independently of the configuration adopted by any other device for fluidic communication 16 of the fermenter 10. In other words, the fluidic communication devices 16 which are located at different heights are independent of one another and are not connected between them in this particular embodiment, nor controlled from outside the fermenter. This feature does not in any way prevent a variant in which the shutter elements 18 (which are described in detail below) of a single fluidic communication device 16, located at the same level. height, move in synchronism, in particular being actuated by a spring and / or being connected to each other.

According to one embodiment having the advantage of its great simplicity while having a high reliability and a good efficiency, each fluidic communication device 16 comprises a plurality of openings 17 each crossing the thickness of the separation wall and a plurality of closure elements 18, where each closure element 18 equips a corresponding opening 17 and varies between:

an open position, corresponding to the first configuration of the fluidic communication device 16, in which the closure element 18 opens the corresponding opening 17 and allows fluid communication between the first and second volumes VI, V2 through the opening 17 to allow the liquid medium and the gas contained in the container 11 to flow freely from one volume to the other through the opening 17,

and a closing position, corresponding to the second configuration of the fluidic communication device 16, in which the sealing element 18 at least partially closes the corresponding opening 17 and blocks all or part of the fluid communication between the first and second volumes VI, V2 through the opening 17 for the liquid medium and the gas contained in the container 11.

In practice in the illustrated example, each opening 17 is a window or hearing through the entire thickness of the inner tube 12, in that this window opens into both the first volume VI and the second volume V2. The shape of the outline of each opening 17 may be arbitrary, for example of rectangular shape as shown. The number of openings 17 that equip each fluidic communication device 16 may be any, for example equal to 4, as shown in the embodiment illustrated in the figures. For a communication device fluidic 16 given, the openings 17 which equip it are arranged at the same given height of the inner tube 12 and are angularly distributed around its axis of extension, at regular pitch or not.

With reference to FIGS. 2 and 3, each fluid communication device 16 may comprise, for each closure element 18, a corresponding connection mechanism 19 making it possible to fix the closure element 18 on the partition wall in such a way that movable between the closing and opening positions. In FIGS. 1, 4A and 4B appended, the open position is shown for all the fluidic communication devices 16. In FIG. 6, the open position is shown for the upper fluid communication device 16. and the closed position is shown for the lower fluid communication device 16. In all the figures, the connecting mechanism 19 makes it possible, for example, to fix the closure element 18 on the inner tube 12.

Each connecting mechanism 19 is configured so that the closure member 18 is mechanically automatically placed in its open position under the action of the difference between the pressure in the volume where the upward flow occurs and the pressure in the the volume where the downward flow occurs, when this difference takes a value greater than the predetermined threshold value already mentioned above.

Each connecting mechanism 19 is configured so that the closure member 18 is mechanically automatically placed in its closed position under the action of the difference between the pressure in the volume where the upward circulation occurs and the pressure in the volume where the downward flow occurs, when this difference takes a value less than or equal to the predetermined threshold value.

According to a simple, economical, reliable and efficient embodiment, the connecting mechanism 19 associated with each closure element 18 comprises a means for articulating the closure element 18 with respect to the partition wall around the closure element 18. a pivot axis 21 located above the corresponding opening 17, the passage from the open position to the closed position and reciprocally occurs by tilting of the closure member 18 about this pivot axis 21 In practice in the illustrated example, the articulation means makes it possible to articulate the closure element 18 with respect to the inner tube 12.

Preferably, the connecting mechanism 19 is such that the pivot axis 21 is permanently disposed in the volume where the circulation occurs. ascending while the closure member 18 is permanently disposed (regardless of its position between its closed position and its open position) in the volume where the downward circulation occurs.

Therefore, in the particular illustrated example of fermenter 10, the pivot axis 21 is disposed in the first volume VI in which the upward circulation of the mixture between the liquid medium and the injected gas takes place while the element shutter 18 is disposed permanently, that is to say whatever its position between its closed position and its open position, in the volume where the downward circulation takes place, which corresponds here to the second volume V2.

This arrangement has the advantage of reinforcing, under normal operating conditions, the self-closing of each closure member 18 towards its closed position under the action of gravity, positioning very advantageously the center of gravity of the locking mechanism. link 19 in the volume (here the first volume VI) where the ascending circulation takes place.

Moreover, for the same purpose, the connecting mechanism 19 associated with each closure member 18 may comprise a support arm 20 having a first end 201 articulated about the pivot axis 21 at the articulation means and a second end 202 connected to the closure member 18. The support arm 20 passes through the thickness of the partition wall, concretely through the thickness of the inner tube 12 in the illustrated example, for example in a zone located above the opening 17 to be closed by the closure element 18 supported by this support arm 20. The support arm 20 could alternatively pass through the thickness of the partition wall through the opening 17. The pivot axis 21 may or may not be integral with the support arm 20. The constituent part of the pivot axis 21 may in particular be integral with the rest of the support arm 20 at the first end 201 .

These arrangements have the additional advantage of allowing a passage to the open position of the sealing member 18 even in the case where the difference between the pressure of the volume where the upward circulation occurs and the pressure of the volume where the circulation descending occurs is weak. In other words, the sensitivity to the second configuration of each device 16 is large and can be obtained under the action of a small pressure difference between the upflow volume and the downflow volume.

Each connecting mechanism 19 comprises, for example, an attachment clevis 22 on which the pivot axis 21 is articulated, which constitutes in practice the aforementioned articulation means, this fixing screed 22 being fixed at the separation wall. In particular, the fixing screed 22 is disposed continuously, that is to say regardless of the position occupied by the closure member 18 between its closed position and its open position, in the volume where the ascending circulation takes place, which corresponds to the first volume VI in the illustrated example. The connection between the inner face of the inner tube 12 and the connecting yoke 22 may be of embedding type, for example by gluing or welding, although any other type of mechanical connection may be envisaged, for example providing for the presence of at least one degree of freedom in translation and / or rotation if necessary.

The predetermined threshold value can be determined by the shape of the support arm 20 and by the depth of the pivot axis 21 inside the upflow volume, determining a vacuum closing force, therefore a minimum difference in pressures. allowing the opening of the closure element 18. The weight of the closure elements 18 and / or the length of the support arms 20 can also be taken into account in the predetermination of the opening / closing threshold.

The general functional principles of the invention having been presented in detail above, the Applicant hereinafter presents a detailed description of three embodiments of fermentor 10 according to the invention, respectively having a useful volume of 3.75 L, 350 L and 840 L.

In the example of fermentor 10 whose working volume is 3.75 L, the total height of the first volume VI where the upflow occurs is equal to 476 mm while the internal diameter of the tube which defines it is 60 mm. The internal diameter of the tube which externally delimits the second volume V2 where the downward circulation occurs is itself equal to 100 mm while its height is equal to 576 mm. There are two fluid circulation devices 16 offset between them along the height of the fermenter 10, respectively located 210 and 322 mm from the bottom of the second volume V2. Each of these two devices 16 comprises at least two openings 17 and two shutter elements 18 corresponding to the same height. More specifically, each opening 17 allows fluid communication between the first volume VI and the second volume V2 and has a rectangular contour of 14 mm by 36 mm. Each closure element 18, made of 1 mm stainless steel, perfectly matches the shape of the outer wall of the tube which delimits the first volume VI. The length of each shutter element is 45 mm while its height is 20 mm. The pivot axis 21 of the arm 20 is shifted inwardly of the first volume VI relative to to the wall of the tube which delimits the first volume VI at a distance of 10.75 mm. The arm 20 has a length of 50 mm and has a maximum angular travel of pivoting between its closed position (in which the arm 20 is oriented vertically) and its open position equal to 61 °. It is thus avoided that the closure element 18 rubs on the inner wall of the tube which externally delimits the second volume V2 and does not get stuck on it.

In the example of fermentor 10 whose useful volume is 350 L, the total height of the first volume VI where the upflow occurs is equal to 3000 mm while the internal diameter of the tube which defines it is 219 mm. The inner diameter of the tube which delimits externally the second volume V2 where the downward circulation occurs is equal to 400 mm while its height is equal to 4000 mm. There are three fluid circulation devices 16 offset between them along the height of the fermenter 10, respectively located at 521 mm, 1354 mm and 2180 mm from the bottom of the second volume V2. Each of these three devices 16 comprises four openings 17 and four shutter elements 18 corresponding to the same height. More specifically, each opening 17 allows fluid communication between the first volume VI and the second volume V2 and has a rectangular contour of 123 mm by 68 mm. Each closure element 18, made of 1 mm stainless steel, perfectly matches the shape of the outer wall of the tube which delimits the first volume VI. The length of each shutter element is 153 mm while its height is 93 mm. The pivot axis 21 of the arm 20 is shifted inwardly of the first volume VI relative to the wall of the tube which defines the first volume VI at a distance of 32 mm. The arm 20 has a length of 75 mm and has a maximum angular travel of pivoting between its closed position (in which the arm 20 is oriented vertically) and its open position equal to 61 °. It is thus avoided that the closure element 18 rubs on the inner wall of the tube which externally delimits the second volume V2 and does not get stuck on it.

In the example of fermentor 10 whose useful volume is 840 L, the total height of the first volume VI where the upflow occurs is equal to 3000 mm while the internal diameter of the tube which defines it is 419 mm. The internal diameter of the tube which externally delimits the second volume V2 where the downward circulation occurs is equal to 600 mm while its height is equal to 4000 mm. There are four fluid circulation devices 16 offset between them along the height of the fermenter 10, respectively located at 321 mm, 996 mm, 1671 mm and 2346 mm from the bottom of the second volume V2. Each of these four devices 16 comprises four openings 17 and four shutter elements 18 corresponding at the same height. More specifically, each opening 17 allows fluid communication between the first volume VI and the second volume V2 and has a rectangular contour of 230 mm by 68 mm. Each closure element 18, made of 1 mm stainless steel, perfectly matches the shape of the outer wall of the tube which delimits the first volume VI. The length of each shutter element is 284 mm while its height is 93 mm. The pivot axis 21 of the arm 20 is shifted inwardly of the first volume VI relative to the wall of the tube which defines the first volume VI at a distance of 32 mm. The arm 20 has a length of 75 mm and has a maximum angular travel of pivoting between its closed position (in which the arm 20 is oriented vertically) and its open position equal to 61 °. It is thus avoided that the closure element 18 rubs on the inner wall of the tube which externally delimits the second volume V2 and does not get stuck on it.

According to another alternative embodiment not shown, the connecting mechanism 19 associated with each closure member 18 comprises firstly a sliding means by translation of the closure member 18 relative to the next partition wall a direction of substantially horizontal translation, the passage from the open position to the closed position and reciprocally being performed by sliding of the closure element 18 along this direction of translation, on the other hand a return member resilient biasing the closure member 18 permanently to its closed position and such that the passage to the open position is practiced in opposition to the mechanical action of biasing the elastic return member on the element d shutter 18.

In this alternative variant, the mechanical biasing action applied by the elastic return member is included in the definition and characterization of each predetermined threshold value beyond which the fluidic communication device 16 passes into its first configuration and the shutter member 18 moves to its open position.

In order to allow a good operating efficiency while preserving the simplicity and economic nature of the fermenter 10, the closure element 18 may comprise a bearing face 181 intended to come against the partition wall, that is to say ie here against the inner tube 12, in its closed position and having a spatial shape complementary to the shape of the zone of the partition wall at which this bearing face 181 comes into contact. This allows in particular to ensure a good efficiency of the closed position, at lower cost.

In the illustrated example of fermenter 10, the outer face of the inner tube 12 is generally cylindrical and convex of circular section, so that the bearing face 181 is a concave surface in a complementary shape of cylinder portion.

In the foregoing, the nature of each closure member 18 can however be arbitrary in its shape as well as its structure or its hardness. In the illustrated example, the shutter element 18 is rigid and takes the form of a simple closure flap, but this is not limiting.

Although the embodiment previously described for the fermenter 10 has many advantages and is particularly effective, alternative solutions can be envisaged for the design of the at least one fluid communication device 16. The constitution of the partition wall in the form of an inner tube 12 is in no way limiting. In addition, it is for example possible to provide flexible flaps without hinge means or shutter elements achieving a partial closure of the opening. It is also possible to provide a mechanization, for example using cylinders, and with sensor detection. It is also possible to form all the closure elements of a fluid communication device 16 in a single tube rotating inside or outside the inner tube 12 and revealing the openings 17 of this device 16 via the rotation of this second tube. An alternative solution is to provide that the tube attached to the inside or outside of the inner tube 12 is slidable in the inner tube according to its height depending on the level.

An additional advantage of the fermenter 10 according to the invention is to be adaptable to existing air lift fermenters.

On the other hand, the fermentor 10 described above has the advantage of not using flotation elements that would otherwise partially obstruct the volume of upward or downward circulation and thus disrupt the flow of fluids vertically: the result is the guarantee a good fluid and homogeneous circulation within the fermenter 10.

Finally, the automatic opening and the automatic closing of the fluidic communication devices 16 make it possible to work so as to use, whatever the height of the liquid medium, the maximum circulation height of the liquid medium: in the event of a drop in the level of the liquid medium in the fermenter 10 then causing a reversal of the pressure differential between the volumes to upward and downward movement, the device or devices 16, located just below the level of the liquid medium opens (s), allowing the flow of fluids to continue between the two volumes. On the other hand, the devices 16 situated at a still lower level remain closed. If the level of liquid medium drops further below this or these open devices, it is one or those still below that will open, but not those located at a height lower than those that have just opened and so right now. Thus, the maximum height is maintained for upward and downward circulation regardless of the level of the liquid medium in the fermenter 10, thus a better stirring and an optimization of the gas exchanges. In the opposite case, in case of rise of the level of liquid medium, the process works upside down in the same way.

Claims

A liquid medium fermenter (10) comprising gas circulation stirring means comprising a container (11) adapted to contain the liquid medium, a partition wall positioned in the container (11) and separating first and second volumes (VI, V2), an injection device (13) of said gas in the lower part of one of the first or second volumes (VI, V2) to create in said volume an upward circulation of the mixture between the liquid medium and the injected gas and a downward circulation of said mixture in the volume not supplied with gas by said injection device (13), characterized in that the partition wall is equipped with at least one fluid communication device (16) first and second volumes (VI, V2) between them configured to automatically vary between:

a first configuration in which the fluidic communication device (16) allows, for the liquid medium and the gas contained in the container (11), a free fluid flow from one volume to the other through said setting device in fluid communication (16), the first configuration being occupied as soon as at the level of the fluidic communication device (16), the difference between the pressure of said mixture in the volume where the upflow occurs and the pressure of said mixture in the volume where the downward flow occurs is greater than a predetermined threshold value,

and a second configuration in which the fluidic communication device (16) blocks all or part of said fluid circulation for the liquid medium and the gas contained in the container (11), the second configuration being occupied as soon as at the fluidic communication device (16), the difference between the pressure of said mixture in the volume where the upflow occurs and the pressure of said mixture in the volume where the downward flow occurs is less than or equal to the predetermined threshold value.

2. A fermenter according to claim 1, characterized in that it comprises a plurality of separate fluid communication devices (16) and arranged in different areas of the partition wall staggered along its height (H).

3. Fermenter (10) according to claim 2, characterized in that each fluidic communication device (16) is autonomous and varies from one configuration to another without external action and regardless of the configuration adopted by any other device fluidic communication (16) of the fermenter (10).

4. Fermenter (10) according to any one of claims 1 to 3, characterized in that each fluidic communication device (16) comprises a plurality of openings (17) passing through the thickness of the partition wall and a plurality of closure elements (18), wherein each closure element (18) equips a corresponding opening (17) and varies between:

an open position, corresponding to the first configuration of the fluidic communication device (16), in which the closure element (18) opens the corresponding opening (17) and allows fluid communication between the first and second second volume (VI, V2) through the opening (17) to allow the liquid medium and the gas contained in the container (11) to flow freely from one volume to another through the opening (17). )

and a closing position, corresponding to the second configuration of the fluidic communication device (16), in which the closure element (18) at least partially closes the corresponding opening (17) and blocks all or part of the the fluidic communication between the first and second volumes (VI, V2) through the opening (17) for the liquid medium and the gas contained in the container (11).

5. Fermenter (10) according to claim 4, characterized in that each fluidic communication device (16) comprises, for each closure element (18), a corresponding connecting mechanism (19) for fixing the shutter member (18) movably on the partition wall between the closed and the open positions.

6. Fermenter (10) according to claim 5, characterized in that each connecting mechanism (19) is configured so that the shutter member

(18) is mechanically automatically placed in its open position under the action of the difference between the pressure of said household in the volume where the upward circulation occurs and the pressure of said mixture in the volume where the downward flow occurs when this difference takes a value greater than the predetermined threshold value.

7. Fermenter (10) according to one of claims 5 or 6, characterized in that each connecting mechanism (19) is configured so that the closure member (18) is mechanically automatically placed in its closed position under the action of the difference between the pressure of said mixture in the volume where the upward circulation occurs and the pressure of said mixture in the volume where the downward flow occurs when this difference takes a value less than or equal to the predetermined threshold value.

8. Fermenter (10) according to any one of claims 5 to 7, characterized in that the connecting mechanism (19) associated with each closure member (18) comprises a hinge means (22) of the closing element (18) with respect to the partition wall around a pivot axis (21) above the corresponding opening (17), the transition from the open position to the closed position and conversely practiced by tilting the closure member (18) about said pivot axis (21).

9. Fermenter (10) according to claim 8, characterized in that the connecting mechanism (19) is such that the pivot axis (21) is disposed in the volume where the upward circulation occurs and in that the shutter element (18) is arranged in the volume where the downward circulation occurs.

10. Fermenter (10) according to any one of claims 8 or 9, characterized in that the connecting mechanism (19) associated with each closure member (18) comprises a support arm (20) having a first end (201) articulated about the pivot axis (21) at the hinge means (22) and a second end (202) connected to the closure member (18), said support arm (20) passing through the thickness of the partition wall.

11. Fermenter (10) according to any one of claims 8 to 10, characterized in that the center of gravity of the connecting mechanism (19) is located in the volume (VI) where the upward flow occurs.

12. Fermenter (10) according to any one of claims 5 to 7, characterized in that the connecting mechanism (19) associated with each closure member (18) comprises firstly a translational sliding means of the closure member (18) with respect to the partition wall in a substantially horizontal direction of translation, the passage from the open position to the closed position and reciprocally being performed by sliding the closure element. (18) along said translation direction, on the other hand an elastic return member urging the closure member (18) permanently towards its closed position and such that the passage to the open position is practiced in opposition to the mechanical action of biasing the elastic return member on the closure member (18).

13. Fermenter (10) according to any one of claims 4 to 12, characterized in that the closure member (18) comprises a bearing face (181) intended to come against the partition wall in the position closing the closure member (18) and having a spatial shape complementary to the shape of the area of the partition wall at which said bearing face (181) comes into contact.

14. Fermenter (10) according to any one of claims 1 to 13, characterized in that the partition wall is formed in an inner tube (12) positioned in the container (11) so that the inner tube (12) ) delimits the first volume internally and externally delimits the second volume (V2) in combination with the container (11).

15. The fermenter (10) according to any one of claims 1 to 14, characterized in that said at least one device for placing in fluid communication (16) is automatic in a manner requiring no manual intervention.