Integrated gas inlet and agitator for gas-liquid reactors

Abstract

The present invention relates to a gas introduction unit for introducing a process gas into a liquid present in a reactor without bubbles, the gas introduction unit comprising: a first gas-receiving chamber and a second gas-receiving chamber spaced apart therefrom, the two gas-receiving chambers being connected to one another via at least two two-dimensional gas-conducting diffusion membranes made of hollow fibers spaced apart from one another and at least a portion of which are fixed to one another; a gas supply receptacle provided in at least one of the gas receiving chambers; a receptacle for the shaft provided in at least one of the gas receiving chambers; The gas introduction unit for introducing gas into the liquid in the reactor can supply process gas via a gas supply receiver and can be set in rotational motion via a shaft receptacle, and convection can be created in the reactor via the rotational motion of the gas introduction unit in the liquid.

Description

[Technical Field]

[0001] The present invention relates to a gas introduction unit for introducing a process gas into a liquid present in a reactor without bubbles, the gas introduction unit comprising at least: a first gas receiving chamber for receiving a process gas and a second gas receiving chamber spaced therefrom for receiving the process gas, the two gas receiving chambers being spaced apart from each other and connected to each other via at least two two-dimensional gas-conducting diffusion membranes made of hollow fibers at least a portion of which are fixed to each other; a gas supply receptacle provided in at least one of the gas receiving chambers; a receptacle for the shaft provided in at least one of the gas receiving chambers; Equipped with The gas introduction unit for introducing gas into the liquid in the reactor can supply process gas through a gas supply receptacle and can be rotated through a shaft receptacle, and convection can be created in the reactor through the rotational movement of the gas introduction unit in the liquid. Furthermore, the present invention relates to a method for gasifying a process liquid, a gas-liquid reactor comprising a gas introduction unit according to the invention, and the use of a gas introduction unit according to the invention for supplying a process gas to a biological culture. [Background technology]

[0002] Ensuring more sustainable production methods for important basic materials is a growing concern for society today. This approach extends not only to production methods, but also to the properties of materials used after their planned lifespan. This is evident from the fact that, in recent decades, for many chemicals synthesized from petroleum, alternative biological production methods have been developed that promise to improve the chemical and biological properties of the produced materials, such as faster degradability, as well as more resource- and energy-efficient production processes.

[0003] This approach is being pursued, particularly for surfactant-based biomolecules, because they have a lasting impact on the environment and can be used in cosmetics, pharmaceuticals, and other applications to offset their currently high production costs through added value. A more environmentally friendly production method is the biological fermentation process, which uses renewable raw materials as a nutrient medium and is carried out under oxygen supply. However, the biosynthesis of proteins and surfactants typically involves the disadvantage of vigorous foaming in the fermenter, which negatively impacts performance and the overall process flow. Until now, gas introduction in such systems has involved generating gas bubbles and then destroying them using a stirrer or antifoaming agent. This should enable foam-free fermentation without biomass loss. However, bubble gassing, which involves the destruction of bubbles, has the disadvantages of complicating process control through additional control parameters and increasing the energy cost of the process through mechanical foam destruction.

[0004] Foam suppressors are not a sustainable alternative because additional purification in the downstream process flow strongly impacts process costs. In this regard, existing fermentation methods and the equipment used therein need to be improved to ensure a simple and reproducible fermentation process without foam formation.

[0005] There are several patent documents that introduce bubble-free gas into fermentation liquid. For example, DE 10 2006 008 687 A1 describes a process for gas exchange, particularly in biotechnology, in particular in cell culture, through one or more immersed membrane surfaces, such as tubes, cylinders or modules, for introducing gas into a liquid, which is characterized in that the membrane surfaces undergo an optional rotational-oscillating movement in the liquid.

[0006] Furthermore, DE 44 046 00 C1 discloses a process for bubble-free gas introduction into microorganisms immobilized on a carrier material in a reactor, in which an oxygen-rich aqueous solution is passed through the carrier material on the upstream side of the carrier material via a membrane coated on one side with an oxygen-containing gas.

[0007] Another patent document, DE 41 42 502 A1, discloses a process for introducing hydrogen into an aqueous liquid without bubbles, in which hydrogen is introduced into the aqueous liquid through a membrane, characterized in that the process uses a) a support structure formed of a porous polymer and b) a membrane comprising at least one layer of non-porous polymer, with the aqueous liquid contacting the membrane on the side of the layer of non-porous polymer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] German Patent Application Publication No. 102006008687 [Patent Document 2] German Patent No. 4404600 [Patent Document 3] German Patent Application Publication No. 4142502 Summary of the Invention [Problem to be solved by the invention]

[0009] Such solutions known from the prior art leave room for further improvement, in particular with regard to the efficiency of feeding the process liquid by the process gas, and with regard to reliably preventing foam formation even in systems with particularly difficult product characteristics. It is therefore an object of the present invention to at least partially overcome the drawbacks known from the prior art, in particular to provide a gas introduction unit and a gas-liquid reactor equipped therewith, in which the gas supply of the process liquid is particularly efficient and uniform and the formation of bubbles during supply is significantly reduced. [Means for solving the problem]

[0010] This problem is solved by the features of the respective independent claims directed to the gas introduction unit according to the invention, the gas-liquid reactor according to the invention, the process according to the invention and the use according to the invention. Preferred embodiments of the invention are set out in the dependent claims, in the description or in the drawings, whereby further features set out or shown in the dependent claims or in the description or drawings can, individually or in any combination, constitute the object of the invention, unless the context clearly indicates otherwise.

[0011] According to the invention, this problem is solved by a gas introduction unit for bubble-free introduction of a process gas into a liquid present in a reactor, the gas introduction unit having at least the following features: a first gas receiving chamber for receiving a process gas and a second gas receiving chamber spaced therefrom for receiving a process gas, the two gas receiving chambers being connected to each other via at least two two-dimensional gas-conducting diffusion membranes made of a plurality of hollow fibers spaced apart from each other and at least some of which are fixed to each other; a gas supply receptacle provided in at least one of said gas receiving chambers; a receptacle for a shaft provided in at least one of said gas receiving chambers; The gas introduction unit that introduces gas into the liquid in the reactor can supply process gas through the gas supply receptacle and can rotate through the shaft receptacle, allowing convection to be formed in the reactor through the rotational movement of the gas introduction unit in the liquid.

[0012] Surprisingly, the above design has proven to provide a highly efficient and flexible gas introduction / agitation combination suitable for a wide variety of (bio)reactor gas introduction applications. The introduction of process gas into the process liquid is highly homogeneous and gentle. The simultaneous gas injection and agitation allows particularly large amounts of process gas to be introduced uniformly into the liquid through the exchange surface. This is due in particular to the fact that the membrane exchange surface is made of hollow fibers, which, due to their constant movement within the liquid, are always free from diffusion of process gas. Thus, on the one hand, the hollow fiber membranes used in the design according to the present invention allow for an overall larger exchange surface than previously known, and on the other hand, are used more efficiently than prior art solutions, since the simultaneous movement of gas sheared at the membrane surface completely avoids diffusional interference caused by attached gas bubbles. Furthermore, since the process gas is supplied centrally and uniformly distributed within the gas receiving chamber, the design is very robust, allowing for high flow rates and strong convection to be generated through the firmly fixed hollow fibers. Furthermore, the combination of gas injection and agitation ensures that the hollow fibers are actively flowing, not just indirectly, with the process liquid. The lack of dead space within the module itself improves gas supply efficiency and contributes to uniform gas introduction. Shear also maintains small bubble size. This feed uniformity, gas abundance, and bubble size control through simultaneous shear effectively prevent the formation of bubbles and / or foam in the liquid medium, making it suitable for applications such as the production of foam-promoting substances and challenging fermentation tasks involving biological cultures. The gas introduction unit can also consist of any number of gas introduction units connected in series, which facilitates cleaning and sterilization of individual modules and facilitates upscaling to larger reaction volumes.

[0013] The gas introduction unit of the present invention is suitable for introducing a process gas into a liquid in a reactor without bubbles. The process liquid in the reactor can be simultaneously agitated and supplied with a process gas by the gas introduction unit of the present invention. That is, the process gas is introduced into the process liquid through the gas introduction unit continuously or discontinuously at time intervals. The introduction of the process gas increases the concentration of the process gas in the liquid in the reactor at the point of introduction, at least temporarily. Possible process gases include oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen, or similar gases or mixtures thereof. Typically, the process gas forms a reactant for further chemical reactions in the process fluid. The structure of the present invention allows the process gas to be supplied into the process fluid without bubbles. In this context, "bubble-free" particularly means that the bubble size of the process gas is in a range in which bubbles on the surface of the film are not visible to the naked eye, or are very difficult to see. For example, the bubble size may be on the order of several microns. The design of the present invention particularly prevents the formation or deposition of bubbles on the surface of the process liquid during the process. The liquid in the reactor can be, for example, an aqueous solution, dispersion, or emulsion. However, this section is not limited to aqueous systems. Non-aqueous liquid systems can also be gassed without bubbles.

[0014] The gas introduction (supply) unit consists of at least a first gas receiving chamber for receiving process gas and a second gas receiving chamber, spaced apart from it, for receiving process gas. The process gas is supplied to one of the two gas receiving chambers via a gas supply line and can be evenly distributed therein. The gas receiving chamber serves as a reservoir for the process gas and can also compensate for possible pressure fluctuations, as opposed to supplying it directly to the membrane. The process gas is then supplied from this gas receiving chamber to the second gas receiving chamber via hollow fiber membranes. The distance between the two gas receiving chambers can be selected as a function of the reactor dimensions, the length and mechanical stability of the hollow fiber membranes, the desired gas input, and the desired flow dynamics. Such gas receiving chambers can be made, for example, of metal or plastic and have rotational symmetry. Furthermore, the two gas receiving chambers have receptacles for the hollow fiber membranes, which allow each hollow fiber membrane to be independently fixed. The receptacle for the hollow fiber membrane is, for example, a groove provided on the surface of the gas receiving chamber, and the hollow fiber membrane can be mechanically sandwiched or adhered thereto to connect it to the gas receiving chamber in an airtight manner.

[0015] The two gas-receiving chambers are connected to each other via at least two two-dimensional gas-conductive diffusion membranes, each consisting of a plurality of hollow fibers spaced apart and at least partially fixed. Thus, the process gas is not introduced into the liquid through the gas-receiving chamber, but through the hollow fiber membranes gas-conductively connected to the two gas-receiving chambers. The hollow fibers are not used as is, i.e., alone. Multiple hollow fibers are arranged next to each other or behind each other, forming a flat membrane from the arrangement of hollow fibers. To further stabilize the membrane, the individual hollow fibers can be fixed to each other by additional mechanical means. For example, the individual hollow fibers can be stabilized to each other in the form of a fabric with non-gas-transporting threads or fibers running perpendicular or nearly perpendicular to the hollow fibers. For example, a fixture in the form of an inert polymer thread, preferably one, more preferably two, or even more preferably three, can be inserted per centimeter of hollow fiber membrane, with the threads passing alternately above and below the hollow fibers, thereby fixing the hollow fibers to each other. Diffusion or microfiltration membranes are membranes in which gases diffuse first through the membrane, then through the hollow fiber shell, and then into the process liquid. Membranes can be dense or porous, with a porosity that, given sufficient flow rate, prevents concentration polarization on the outside of the membrane and the associated outgassing of gases introduced in the form of bubbles. Non-"dense" membranes can have pore sizes ranging from 20 nm to 20 μm. "Dense" diffusion membranes can be multilayered. This allows for additional layers to prevent process liquid from entering the membrane and, if necessary, back-diffusion of unwanted gases into the membrane. Furthermore, layered composite structures allow extremely thin membranes of dense material to be reliably supported on a mechanically strong active layer, such as porous PMP, TMCTS, or PDMS / silicone. This thin, dense layer is critical for the permeability of the gases used. As thin as possible, the thinnest possible layer ensures high mass transport. The ratio of mass transport rate through the membrane to membrane thickness is reciprocal for dense membranes. However, thin active layers are usually mechanically unstable and require a carrier, a so-called support, which is as porous as possible and offers negligible resistance to the ingress of gases into the process fluid.The hollow fibers that can be used are, for example, made of PMP (polymethylpentene) and have an inner diameter of 0.2 mm and an outer diameter of 0.38 mm. Alternatively, PDMS (polydimethylsiloxane) / silicone membranes can be used, with an inner diameter of about 0.3 mm and an outer diameter of about 0.5 mm. Preferably, 50 or more, more preferably 100 or more, and even more preferably 500 or more hollow fibers are arranged next to or behind each other to form a planar membrane array from the individual hollow fibers. A planar arrangement occurs when, preferably, 40% or more, more preferably 50% or more, even more preferably 60% or more of the area between two spaced, non-directly adjacent hollow fibers is covered by additional hollow fibers. Such a planar arrangement can be achieved, for example, by fixing hollow fibers of the above dimensions on a gas-receiving chamber at intervals of 0.05 mm or more, 2.5 mm or less, and even more preferably 0.1 mm or more, but 1 mm or less. The gas flows through a gas receiving chamber into the joined hollow fibers to form a membrane, and then releases into the liquid phase outside the fibers in response to a driving force.

[0016] The gas introduction unit is composed of at least two diffusion membranes. This means that not only does one membrane of a plurality of hollow fibers with a continuous gas path extend from the gas receiving chamber into the process liquid to the second gas receiving chamber, but also at least two membranes of a plurality of hollow fibers spaced apart from each other are arranged in the first gas receiving chamber, allowing gas to be supplied to the process liquid via a separate gas path. Preferably, there may be 10 or more, more preferably 50 or more, and even more preferably 100 or more, individual membranes of hollow fibers extending from the first gas receiving chamber into the process liquid.

[0017] Individual hollow fibers can be connected to the gas-receiving chamber by mechanically clamping the fibers in a specially designed device above the gas-receiving chamber or by gluing the membrane to the gas-receiving chamber in that manner. Preferably, the individual hollow fiber membranes can be glued to the gas-receiving chamber. A gas supply receptacle is located in one of the gas receiving chambers. The gas receiving chamber can be supplied with process gas from the outside via a supply line running through the reactor. For this purpose, an external gas source can be supplied to the gas receiving chamber from the inside of the reactor via a hose or capillary system. The hose or capillary can then be connected to a receptacle in the gas receiving chamber designed for this purpose. This can be done in a gas-tight manner, for example, by a fitting. Preferably, a metric flangeless flat-bottom connection element with a flangeless ferrule can be used as the fitting. The fitting can be made of metal or plastic, for example, PEEK. The fitting can be located either centrally or off-center in the gas receiving chamber; preferably, it is located on the side of the gas receiving chamber facing the hollow fiber membrane. Depending on the operating mode of the gas introduction unit, only one or both gas receiving chambers can be equipped with a gas supply receptacle. In particular, the gas introduction unit can operate in two modes: On the one hand, the gas supply can be operated in a "cross-flow" mode or alternatively in a "dead-end" mode, in which gas is delivered only to the gas receiving chamber of the gas introduction unit. In this mode, no pickup in another gas receiving chamber, for example, is required to discharge the unintroduced process gas.

[0018] A shaft receptacle is located in one of the gas receiving chambers. To input the mechanical energy required to move the gas introduction unit, one of the gas receiving chambers is configured with a device for receiving the shaft. The shaft is guided through the reactor and connected to a drive or gearbox, which can rotate the shaft. The rotating shaft also rotates the gas introduction unit and moves the process stream across the flat hollow fiber membrane. The movement of the shaft, and therefore the gas introduction unit, can be unidirectional or, preferably, bidirectional. Thus, constant or alternating rotational movement of the gas introduction unit with different speeds can be achieved.

[0019] The gas introduction unit supplies process gas through a gas supply inlet for introducing the gas into the liquid in the reactor. The gas introduction unit is then set in rotational motion through a shaft inlet, thereby creating convection in the reactor through the rotational motion of the gas introduction unit in the liquid. Both mechanical energy and process gas can be transferred to the gas introduction unit through the gas and shaft inlets. The process gas is released into the process liquid through the hollow fiber membrane, and the rotational motion of the gas introduction unit and the flattening of the hollow fiber membrane create a directional flow in the liquid in the reactor.

[0020] In a preferred embodiment of the gas introduction unit, the projection of the diffusion membrane onto the gas receiving chamber can have an arcuate shape. To create a uniform flow profile within the reaction liquid and to ensure uniform overflow of the individual hollow fibers within the gas introduction unit, it has proven particularly suitable for the individual hollow fibers not to be arranged in a straight line, but rather to be spaced apart from one another both longitudinally and transversely across the gas receiving chamber. Thus, within the framework of the membrane's planar design, the resulting alignment surface of the hollow fibers is curved rather than straight. In addition to improving and uniforming the flow profile, this design can also contribute to improving gas penetration into the liquid, particularly by uniformly shearing bubbles from the hollow fiber membrane surface. In particular, it can also delay or completely prevent the formation of larger gas bubbles at the membrane surface. Possible embodiments of the arcuate shape are shown in the figures. Preferably, the arc is 1 m long. -1 Over 100m -1 Less than 5m, more preferably -1 Over 70m -1 It may have the following curvature:

[0021] In a further preferred embodiment of the gas introduction unit, the gas supply receptacle and the shaft receptacle can be located in only one gas receiving chamber. To ensure a uniform flow profile within the reactor, it has proven particularly advantageous to centrally locate the gas inlet and the drive shaft connection in one gas receiving chamber. Even more preferably, both the gas receiver and the shaft receiver can be designed together, for example in the form of a hollow shaft, so that both receivers are located within one connection of the gas introduction unit. This can help reduce the number of mechanical components on the gas introduction unit. Furthermore, this combined port can preferably be designed centrally on the gas introduction unit. Preferably, the gas introduction unit can simultaneously supply the process gas and the required kinetic energy through only a receptacle integrated into one of the gas receiving chambers. This allows for a particularly uniform flow profile in the gas introduction unit and reduces the effort required to connect the equipment. The latter also contributes to improved cleanability and sterilization of the gas introduction unit.

[0022] In a further preferred embodiment of the gas introduction unit, the two gas receiving chambers are each cylindrical and may be connected to each other by one or more mechanical supports. A rotationally symmetric cylindrical shape has proven particularly advantageous for creating the most efficient convection possible with most reactor geometries. This design of the gas receiving chambers allows for reproducible, highly uniform, and strong flows both within the gas introduction unit and within the reactor itself, contributing to particularly good process gas supply to the process liquid. In addition to fixing the relative positions of the two gas receiving chambers to each other via hollow fiber membranes, it has also proven advantageous to fix the relative positions of the two gas receiving chambers to each other via one or more mechanical supports. This measure can reduce synchronization and unwanted vibrations of the gas introduction unit at high speeds. Preferably, the supports can be guided through the centers of the two cylindrically designed gas receiving chambers. This embodiment can improve the flow profile within the gas introduction unit, particularly between the individual hollow fiber membranes.

[0023] According to a preferred feature of the gas introduction unit, at least one retaining disk can be placed between the two gas receiving chambers on the mechanical support and designed to mechanically hold the diffusion membrane. To achieve mirror-symmetric convection in many different reactor geometries, it has proven particularly advantageous to place a retaining disk between the two gas receiving chambers on the support, in mechanical contact with the hollow fiber membrane. The hollow fiber membrane can either be "loosely" fixed by the mechanical retention of the retaining disk, or it can be stretched or twisted from its fall line by the retaining disk. In the former case, holding the hollow fiber membrane in place also allows for greater mechanical forces to be realized without risking membrane damage, for example, due to higher circulation speeds in the gas introduction unit. More fragile hollow fibers can be used. In addition to the mechanical work of holding the membrane, the retaining disk can also influence the achievable flow shape. Individual hollow fiber membranes can be selectively deflected or twisted from the shape determined by their connection to the gas receiving chamber. This deflection changes the membrane's planar shape, generating unique convective flow patterns in the fluid. In this way, the membrane can be tailored to the specific gas processing task and reactor geometry.

[0024] In a preferred embodiment of the gas introduction unit, the mechanical support can be adapted to transport process gas from the gas receiving chamber. In order to achieve the most compact possible design of the gas introduction unit with improved supply to the unit in cross-flow operation, it has proven particularly suitable for the mechanical support to be in the form of a hollow shaft that can also transport process gas to and from the gas receiving chamber.

[0025] In a further preferred embodiment of the gas introduction unit, the area ratio of the total hollow fiber cross-sectional area to the cross-sectional area of ​​the gas receiving chamber can be 5% or more and 45% or less. The proposed design allows for a compact gas introduction unit with a significantly larger process gas exchange area compared to prior art solutions. These larger exchange areas exhibit a lower tendency for bubble formation and also result in more favorable flow behavior of the gas introduction unit. The total hollow fiber cross-sectional area is calculated by multiplying the cross-section of a single hollow fiber by the number of fibers arranged on the gas receiving unit. The cross-sectional area of ​​the gas receiving section results from the area of ​​the gas receiving section to which the process gas is supplied. If the gas receiving chamber has a central or outer surface to which no process gas is supplied and therefore no hollow fiber membranes can be attached, this surface does not contribute to the above ratio, even if the gas receiving chamber includes this surface. In a preferred embodiment, the area ratio can be 7.5% or more and 20% or less, more preferably 10% or more and 15% or less. Within these ratios of the gas exchange area to the gas receiving chamber, large amounts of process gas can be introduced under uniform flow conditions.

[0026] In a further preferred embodiment of the gas introduction unit, the packing density of the diffusion membrane relative to the volume of the gas introduction unit is expressed as the surface area of ​​the hollow fiber divided by the volume of the gas introduction unit, and is 0.1 cm -1 Over 7.5cm -1 or less. In this case, the total surface area of ​​the hollow fibers can be calculated using the number and surface area of ​​the hollow fibers through which the process liquid can freely pass. In the case of cylindrical or non-cylindrical shapes, the total volume of the gas introduction unit is determined via the volume of the gas introduction unit that can access the process liquid between the gas receiving chambers. With the design according to the present invention, a very high activity gas introduction area can be accommodated in a small space, which can contribute to the efficient supply of very high reactor volumes as well as high process gas flows combined with simultaneous stirring. Preferably, this ratio is also less than 0.25 cm. -1 Over 6cm -1 Less than 0.5cm, more preferably -1 More than 3cm -1It can be as follows:

[0027] The present invention further provides a method for introducing a gas into a process liquid in a reactor, the gas introduction being carried out via a gas introduction unit according to the present invention. Introducing a gas into a process liquid via a gas introduction unit according to the present invention can have several process advantages. This process step allows for a large amount of process gas to be homogeneously distributed throughout the fluid volume, and the combination of agitation and gas introduction results in the introduction of no or very small bubbles. Direct contact with the fluid boundary and immediate shearing of bubbles from the membrane surface avoids diffusion inhibition due to concentration polarization at the hollow fiber surface, and, in contrast to a static arrangement, all fibers are in uniform motion, resulting in a larger liquid volume being delivered to the reactor. In particular, this process allows for the creation of convective currents, thereby avoiding dead zones within the reactor and the gas introduction unit.

[0028] In a preferred embodiment of the method, the rotational speed of the membrane surface at the outermost periphery of the gas introduction unit may be 0.1 m / s or more and 5 m / s or less. The setup according to the present invention allows even inherently mechanically unstable diffusion membranes to operate under high shear rates in the liquid. Without being bound by theory, this is attributed to the fact that the spaced hollow membrane surfaces, flowing through or over the liquid, absorb only a portion of the liquid's kinetic pulses. Advantageously, this results in stripping of the diffused process gas and a reduction in mechanical stress. The speed of the gas introduction unit can be adjusted by the dimensions of the gas receiving chamber area and the rotational speed of the gas introduction unit. The hollow fibers furthest from the center of the gas introduction unit have the highest rotational speed. Therefore, hollow fibers located further inside the gas introduction unit have a lower circulation speed. More preferably, the revolutional speed of the membrane surface at the outermost periphery of the gas introduction unit can be 0.25 m / s or more and 4 m / s or less, and even more preferably 0.5 m / s or more and 3 m / s or less.

[0029] According to the present invention, a gas-liquid reactor comprises at least an outer reactor shell, a drive unit, a gas supply unit, and a gas introduction unit according to the present invention. The reactor according to the present invention is a gas-liquid reactor for bubble-free gasification of a process liquid with a process gas. A gas-liquid reactor within the meaning of the present invention is bounded by an outer shell, which can be made, for example, of steel or glass, and has a space inside which the process liquid can be filled at different filling levels. In particular, disposable reactors made of plastics such as PP, PC, PET, LDPE, EVA, and PVDC, as well as composite systems made of these plastics, are also possible. The process liquid may contain other components, such as reactants, suspended cells or organisms, salts, pH adjusters, or other substances, in addition to the liquid. The process liquid may be in the form of, for example, an aqueous solution, dispersion, or emulsion. The gas introduction unit can be connected to a supply line for the process gas via a gas inlet. The process gas can be present in an additional reservoir, such as a gas bottle, and is supplied in a controlled manner via a control valve. The gas flow rate and gas composition to the gas introduction unit can be adjusted by a control device. For example, a gas valve can regulate the transmembrane pressure between the inside of the membrane of the gas introduction unit and the process liquid outside the membrane, e.g., in the form of a fermentation broth. The gas input to the broth typically increases proportionally to the transmembrane pressure. When gas flows continuously across the inside of the membrane, the operating mode is set to "crossflow." In this case, the gas valve is opened in dead-end operation mode. This is particularly effective when gas from the process, such as CO2 in conventional aerobic fermentation, enters the membrane along a concentration gradient and concentrates there. This concentration can lead to a decrease in the overall performance of the gas introduction because the partial pressure of the introduced gas decreases, reducing the driving force. Furthermore, condensed water that has penetrated the membrane through the pores can also be rapidly / intermittently vented in this way. A particularly noteworthy advantage of "dead-end" gas introduction is that only gas molecules that are stoichiometrically metabolized in the process are "introduced," i.e., used. This has implications for the economics of the (bio)process.In addition to these minimum components, the reactor can of course have other internal components. For example, additional components such as sensors, supply and discharge lines, heaters and / or cooling devices can be located inside the reactor. The heating or cooling devices can also be located outside the reactor.

[0030] In a preferred embodiment of the gas-liquid reactor, the reactor can have no further stirring units in addition to the gas introduction unit. To create a particularly efficient flow profile with uniform mixing of the process liquid present inside the gas introduction unit, it has proven suitable for the reactor to have no further active movement devices for generating a directional flow of the process liquid. In this case, the process liquid flows particularly directional around the hollow fibers, allowing a large portion of the process gas diffusing from the hollow fibers to be sheared. The use of additional active stirring units would disrupt the achievable convective symmetry and could result in different gas inputs per unit volume of process liquid.

[0031] In a further preferred embodiment of the gas-liquid reactor, at least one flow breaker may be arranged between the reactor shell and the gas receiving chamber. In addition to a highly symmetrical design of the convective flow, it may be useful to redirect the convective flow induced through the gas supply and stirring unit of the present invention in certain regions of the reactor using a flow breaker. This can contribute to better adaptability to certain reactor geometries. The flow breaker can be arranged between the gas introduction unit and the reactor wall, and between the gas introduction unit and the reactor bottom and lid. Particularly preferably, at least one flow breaker is installed between the gas introduction unit and the reactor lid. This flow breaker can also be disk-shaped. This flow breaker can help prevent uncontrolled absorption of gas from the head gas space of the reactor, especially in the case of a high exchange area and high circulation rate of the gas introduction unit. In particular, it effectively prevents coning of the process liquid toward the gas introduction unit. Preferably, the disk-shaped flow breaker can be installed at a height of at least ¼ but not more than ¾ of the distance from the top of the gas introduction unit to the liquid level.

[0032] The present invention also relates to the use of a gas-liquid reactor according to the present invention to supply process gas to a biological culture suspended in a process solution or attached to the interior of the reactor or to a gas introduction unit. Biological cultures, such as bacterial or fungal forms, can be grown in a bioreactor in two different ways. First, the organisms can be present in solution, for example in the form of a suspension, or attached to a surface. Biofilm cultivation can, in principle, be carried out on the walls of the reactor or on the gas introduction unit according to the present invention. The latter is preferred according to the present invention, since a more uniform nutrient supply can be ensured under dynamic gas introduction and stirring conditions. In this respect, higher yields and faster conversions can be achieved. The reactor design according to the present invention has proven particularly suitable for the growth of microorganisms in aqueous fermentation media. The reactor design according to the present invention allows for targeted and reproducible introduction of an adaptive gas amount into the reaction medium, with only a small portion of the mixing of the entire reactor volume being disrupted by the gas introduction unit. The low mixing eliminates dead zones, allowing for uniform and rapid distribution of process gas demand, such as oxygen, throughout the entire volume of the process liquid. Microorganisms are organisms capable of thriving within the reactor. As for further advantages of the process according to the invention, explicit reference is made to the advantages of the gas introduction unit according to the invention.

[0033] The present invention also provides the use of a gas-liquid reactor to supply oxygen to bacteria in a nutrient medium. In particular, the reactor of the present invention can be used to supply oxygen to bacteria in a nutrient medium. Bacteria, in particular, exhibit varying process gas requirements as a function of their growth stage in the nutrient medium. Homogeneous dispersion and uniform distribution of the introduced oxygen are particularly challenging in these cases, as the gas introduction system must have sufficient reserves to selectively introduce both low and high amounts of oxygen into the nutrient medium. In such cases, a high degree of transmembrane pressure flexibility is required, for example, to reproducibly introduce low amounts and to introduce high amounts without bubbling. An example of a usable bacterium is Pseudomonas putida (P. putida), a Gram-negative, rod-shaped bacterium found in water, soil, and plants. In Germany, the laboratory strain P. putida 5 KT2440 is classified as an S1 organism and has GRAS status. P. putida KT2440 is of great interest for industrial biotechnology due to its remarkable tolerance to organic solvents and diverse metabolism. Furthermore, P. putida is a suitable organism for heterologous gene expression and has a high growth rate on glucose.

[0034] In a further preferred embodiment of the use, the biological culture can be adapted to produce foam-forming substances. Foam-forming substances, especially biosurfactants, are particularly difficult to ferment in conventional reactors because these surfactants naturally contribute to particularly strong foam formation. One example of a biosurfactant is rhamnolipid, a surface-active molecule produced by a biocatalyst. Unlike petroleum-based surfactants, this biosurfactant is rapidly metabolized biologically, offering the ecological advantage of being highly environmentally compatible. These biosurfactants can be particularly advantageously produced in the reactor of the present invention using the gas introduction unit of the present invention. Other biosurfactants are produced by various microorganisms. These include, in particular, sophorolipids produced by yeast. Sophorolipids belong to the glycolipid family. Another biosurfactant that belongs to the lipopeptide family is surfactin, produced by Bacillus subtilis. Surfactin is primarily used in the medical field. These biosurfactants can be produced with almost no foaming by using the gas introduction unit of the present invention.

[0035] In a preferred embodiment of the use, the membrane area of ​​the diffusion membrane relative to the reactor filling volume (membrane area cm 2 reactor filling volume cm 3 (divided by 0.05cm) -1 More than 1.0cm -1 The membrane area to reactor volume ratio may be: 0.05 to 0.05. In particular, for cell culture and biomolecule synthesis in bioreactors, the above-mentioned ratio of membrane area to reactor volume has proven to be particularly advantageous. This ratio allows for a sufficient supply of process gas at different growth stages, where the amount of biomass varies significantly, and also allows for a well-controlled input of process gas at the beginning of cell growth. This design allows for a highly controllable amount of process gas to be supplied as needed, and an adapted amount at later growth stages if the transmembrane bridge is sufficiently small.

[0036] Further advantages and advantageous embodiments of the subject matter according to the invention are shown by the figures and explained in the following examples, it being noted that the figures are illustrative and are not intended to limit the invention in any way. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 2 is a plan view of a gas receiving chamber in an embodiment according to the present invention. [Figure 2] 10 is a plan view of a gas receiving chamber according to a further embodiment of the present invention; FIG. [Figure 3] 1 is a perspective view showing an embodiment of a gas introduction unit according to the present invention. [Figure 4] 1 is a front view showing an embodiment of a gas introduction unit according to the present invention. [Figure 5] 1 is a schematic cross-sectional view of a gas introduction unit according to the present invention. [Figure 6] FIG. 2 is a cutaway view of a gas introduction unit according to the present invention. [Figure 7] 1 is a schematic cross-sectional view of a reactor according to the present invention, equipped with a gas introduction unit according to the present invention. [Figure 8] 1 is a schematic front view of a reactor according to the invention with a gas introduction unit according to the invention, including possible convection profiles; FIG. [Figure 9] FIG. 1 is a schematic front view of a gas introduction unit according to the present invention, which is composed of two gas introduction units connected in series. [Figure 10] FIG. 1 is a schematic perspective view of a gas introduction unit according to the present invention, which is composed of two gas introduction units connected in series. [Figure 11] 1 is a schematic front view of a gas introduction unit according to the invention consisting of two series-connected gas introduction units with media supply; FIG. [Figure 12] 1 is a schematic front view of a reactor according to the invention having two series-connected gas introduction units with media feed. [Figure 13]1 is a schematic front view of a reactor according to the invention having two gas introduction units connected in series according to the invention, including possible convection profiles. FIG. [Figure 14] 1 is a schematic exploded view of a gas introduction unit according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0038] FIG. 1 is a schematic plan view of a gas receiving chamber 1. The gas receiving chamber 1 is cylindrical and divided into an internal region consisting of a process gas receptacle 4 and / or a shaft receptacle 4. The gas receiving chamber 1 is supplied with both process gas and mechanical drive energy via the receptacle 4. The process gas is introduced from the receptacle 4 into the gas receiving chamber 1 via a trapezoidal connection 5. The gas receiving chamber 1 has a closed surface 2, which is provided with a corresponding recess 3 for receiving a diffusion membrane (not shown in this figure). The diffusion membrane in the form of a hollow fiber can be clamped or glued into the recess 3, extending into the interior of the gas receiving chamber 1. This creates a continuous gas conduction path from the receptacle 4 through the connection 5 to the hollow fiber membrane inside the gas receiving chamber 1. The recess 3 can also be referred to as the diffusion membrane fixing surface 3. The shape of the diffusion membrane fixing surface 3 determines the planar arrangement of the diffusion membrane. In this embodiment, the diffusion membrane mounting surface 3 has an arcuate configuration, so that the hollow fibers mounted in these recesses have a similarly arcuate membrane surface overall. The upper and lower gas receiving chambers 1 can have mirror-image configurations. However, it is also possible for one of the two gas receiving chambers 1 to have no receptacle for further processing means. During operation, the gas receiving chamber 1 can be protected from direct access by the process medium by a lower or upper cover.

[0039] Compared to FIG. 1, FIG. 2 shows essentially the same arrangement of the surface of the gas receiving chamber 2, the diffusion membrane fixing means 3, the receiving means for the process gas and / or the shaft, and the connection 5 to the gas receiving chamber with the gas receiving means 4. In contrast to FIG. 1, now individual cylindrical hollow fibers are shown inserted into the diffusion membrane fixing surface 3. Thus, it is clear that the membrane is not a continuous, flat membrane, but rather consists of a large number of individual hollow fibers offset from one another in the X and Y directions, following the arc-shaped configuration of the diffusion membrane fixing surface 3. In this respect, the diffusion membrane has an arc-shaped shape. In addition to fixing the hollow fibers in the two gas receiving chambers 1, the individual hollow fibers can also be mechanically fixed to one another (not shown in this figure). This additional fixation can be achieved, for example, by fibers woven or braided into the membrane perpendicular to the symmetry axis of the hollow fibers. The hollow fibers and additional fixing fibers thus form a lattice, which can be adjusted to the required mechanical load capacity of the diffusion membrane as a function of the number of additional fixing points and the mechanical properties of the additional fibers.

[0040] FIG. 3 illustrates an embodiment of a gas introduction unit 10 according to the present invention. The entire gas introduction unit 10 is visible in this view. The gas introduction unit 10 is supplied with process gas and energy via a supply line 9. The supply line opens into a gas supply / shaft receptacle 4 (not shown) in the first gas receiving chamber 1. The gas receiving chamber 1 now includes a top cover. Extending from the gas receiving chamber 1 are individual diffusion membranes 6, which extend entirely from the first gas receiving chamber 1 (shown here at the top) to the lower gas receiving chamber 1. The planar design of the diffusion membranes 6 is particularly visible in this view, achieved by the specific arrangement of the hollow fibers. The diffusion membranes 6 extend from the first gas receiving chamber 1 to the second gas receiving chamber 1 and are centrally secured by a retaining disk 7. Therefore, gas conduction between the individual diffusion membranes 6 is not impeded between the gas receiving chambers 1. The diffusion membranes 6 can only be held by the holding disk 7, which can deflect them from their original position or mechanically tension them. The holding disk 7 can thus change the orientation of the individual diffusion membranes 6, which naturally affects the convection achievable by the gas introduction unit 10. The figure also shows a flow breaker 8 positioned above the gas generation unit 10 in the direction of the reactor headspace. This flow breaker is optional and can prevent the formation of vortices in the reaction liquid, especially at very high rotation speeds of the gas introduction unit 10. This can further suppress the generation of bubbles.

[0041] FIG. 4 is a front view of a gas introduction unit 10 according to the present invention. The gas introduction unit 10 is supplied with process gas and mechanical energy via supply lines 9. The supply lines open into a gas supply / shaft receptacle (not shown) in the first gas receiving chamber 1. Extending from the gas receiving chamber 1 are individual diffusion membranes 6 that extend entirely from the upper gas receiving chamber 1 to the lower gas receiving chamber 1. The diffusion membranes 6 extend from the first gas receiving chamber 1 to the second gas receiving chamber 1 and are centrally held by a holding disk 7. Also shown in this view is a flow breaker 8 positioned above the gas introduction unit 10 toward the head space of the reactor.

[0042] 5 shows an example of a media supply in a gas introduction unit 10 according to the present invention. The gas introduction unit 10 is driven by a hollow shaft 9 connected to the gas receiving chamber 1 by a gas supply / shaft receptacle 4. The shaft transports both mechanical energy and process gas to the gas receiving chamber 1. The gas is guided to the internal gas receptacle 11 via the gas supply receptacle 4 and the connecting gas receptacle. Each hollow fiber membrane 6 is arranged on the gas receiving chamber 1 so that it extends to the internal gas receptacle 11. The hollow fiber membranes are thus supplied with process gas from the internal gas receptacle 11 and guided to the other gas receiving chamber 1 via the hollow fibers of the diffusion membrane 6. The process gas can then be passed through the hollow fibers of the diffusion membrane 6 into the process liquid, thereby supplying the process liquid with the process gas. The two gas receiving chambers 1 are additionally connected to each other via a mechanical support 12. This support can be used for other technical functions in addition to purely mechanical support. In this embodiment, the second (lower) gas receiving chamber 1 also constitutes the process gas receptacle 4. Process gas that does not diffuse from the membrane 6 is discharged from the gas introduction unit 10 via the support 12 in the form of a hollow shaft. In this way, the gas introduction unit 10 is operated in a "cross-flow" mode. Typically, process gases can be supplied as well as exhausted through a central hollow shaft 12, which can also serve as mechanical support. In particular, the latter design can reduce the number of connection points required.

[0043] FIG. 6, like FIG. 5, illustrates the media flow in a gas introduction unit according to the present invention. The gas introduction unit 10 is supplied with process gas and / or mechanical energy by a receptacle 4. The receptacle 4 is connected to the gas receiving chamber 1, through which the process gas is supplied to the inner gas receiving chamber 11. Each hollow fiber membrane 6 is arranged above the gas receiving chamber 1 and extends into the gas receiving chamber 1. The hollow fiber membranes 6 are thus supplied with process gas from the inner gas receiving chamber 11, which then passes through the hollow fibers of the diffusion membrane 6 to the other gas receiving chamber 1. The process gas can then pass through the hollow fibers of the diffusion membrane 6 into the process liquid, thereby supplying the process liquid with the process gas. This further connects both gas receiving chambers 1 to each other via a mechanical support 12, through which the process gas can also be optionally guided. In this embodiment, the second (lower) gas receiving chamber 1 also constitutes a receptacle 4 for the process gas. Any process gas that does not diffuse from the membrane 6 is discharged from the gas introduction unit 10 via the gas line of the mechanical support 12. In this embodiment, the gas introduction unit 10 can be operated in "cross-flow" mode. Generally, therefore, the supply 4 as well as the discharge of the process gas can be effectively effected via a central mechanical support 12 in the form of a hollow shaft. In particular, the latter design can reduce the number of connection points required.

[0044] Figure 7 shows a bioreactor 20 according to the invention, inside which a gas introduction unit 10 according to the invention is arranged. The reactor 20 is filled with process liquid, which is present in the reactor 20 up to a process liquid level 21. The gas introduction unit 10 is held in the reactor 20 and moves within the reactor 20 by a process gas / mechanical energy supply in the form of a hollow shaft 9. Further structure of the gas introduction unit 10 can be understood from the description of Figure 5. Furthermore, further flow breakers or conductors 8 can be arranged on the reactor wall 22 or in the liquid volume of the reactor 20 (not shown in this figure), so that the convection of the process liquid can be influenced by this further flow breaker 8.

[0045] FIG. 8 shows one possible design for a reactor 20 according to the present invention, equipped with a gas introduction unit 10 according to the present invention. This figure illustrates one possible way to create a convective flow within the reactor 20. The convective flow results from a simulation of the flow behavior as a function of the geometry of the reactor 20 and the gas introduction unit 10. It can be seen from this figure that the gas introduction unit 10 creates a highly symmetric convective flow, which actively flows through the interior of the gas introduction unit 10 as well. This, in particular, contributes to the efficient introduction of process gas into the process liquid through the diffusion membrane 6. In particular, the convective flow of the process liquid around each hollow fiber 6 forms small bubbles that are sheared from the surface of the hollow fiber 6, allowing the process gas to be delivered to the process liquid. This also helps to keep the bubble diameter on the surface of the hollow fiber small.

[0046] Figure 9 shows a series-connected gas introduction unit 30 consisting of two individual gas introduction units 10 connected via a modular coupling 31. Both process gas and mechanical motion are transferred from the upper gas introduction unit 10 to the lower gas introduction unit 10 via the modular coupling 31. By interconnecting multiple gas introduction units 10, process gas can be supplied very efficiently to reactors of different geometries and sizes. The resulting design ensures reliable and predictable convection with as few connections as possible. This also means that upscaling to larger reactors 20 is easily possible, especially via series-connected gas introduction units 30.

[0047] FIG. 10 shows the embodiment of FIG. 9 from another perspective.

[0048] FIG. 11 shows an example of a media supply arrangement in which two gas introduction units 10 are connected in series. The gas introduction units 10 are driven by hollow shafts 9 connected to gas receiving chambers 1 by gas supply / shaft receptacles 4. Via the gas supply receptacles 4 and the connecting gas inlet chamber gas receptacles 5, gas is supplied to the other gas receiving chamber 1 via the respective hollow fiber membranes 6. From this second gas receiving chamber 1, the remaining process gas can pass to the second gas introduction unit 10 via a modular coupling 31. The modular coupling 31 between the two gas introduction units 10 allows both the transfer of process gas and the transfer of mechanical drive energy between the individual gas introduction units 10.

[0049] 12 shows an embodiment of a reactor 20 according to the present invention in which a gas introduction unit 30 consisting of two individual gas introduction units 10 is connected in series. By connecting a plurality of gas introduction units 10 in series, it becomes possible to reliably supply process gas even to a reactor 20 having a particularly large aspect ratio.

[0050] 13 shows a possible flow profile for a reactor 20 with two gas introduction units 30 connected in series, resulting in a uniform convection of the process liquid both throughout the reactor area and within the series-connected gas introduction units 30.

[0051] FIG. 14 is an exploded perspective view of a gas introduction unit 10 according to the present invention. The gas introduction unit 10 is driven, for example, by a hollow shaft (not shown in this figure) connected to the gas receiving chamber 1 by a receptacle 4. The shaft provides mechanical power to the gas introduction unit and simultaneously transports the process gas to the gas receiving chamber 1. The individual hollow fiber membranes 6 are arranged above the gas receiving chamber 1 so that they extend into the inner gas receiving chamber 11. The hollow fiber membranes are thus supplied with the process gas from the inner gas receiving chamber 11 and guided to the other (lower) gas receiving chamber 1 via the hollow fibers of the diffusion membrane 6. The process gas can pass through the hollow fibers of the diffusion membrane 6 into the process liquid, thereby supplying the process gas to the process liquid. Both gas receiving chambers 1 are thus connected to each other via a mechanical support 12. This support 12 can be used for other technical functions in addition to purely mechanical support. In this embodiment, the second (lower) gas receiving chamber 1 also constitutes a receptacle 4 for the process gas. Any process gas that does not diffuse from the membrane 6 is guided back out of the gas introduction unit 10 via the hollow shaft of the mechanical support 12. Thus, in this embodiment, the gas introduction unit 10 operates in a "cross-flow" mode. Generally, the process gas can enter and exit through a central hollow shaft in the mechanical support 12, which is connected to the periphery of one or both gas receiving chambers 1 via receptacles 4. In particular, the latter embodiment reduces the number of required connections, contributing to a more compact design. Furthermore, in this embodiment, it can be seen that the individual gas receiving chambers 1 can be protected from above and below by cover plates. [Explanation of symbols]

[0052] 1. Gas Receiving Room 2. Surface of the gas receiving chamber 3 Diffusion membrane fixing surface 4 Gas Supply / Shaft Receptacles 5 Connection gas intake Internal gas intake 6 Diffusion membrane 7 Retaining disc 8 Flow Breaker 9 Process gas / mechanical energy supply 10 Gas introduction unit 11 Internal gas receiving chamber 12 Support 20 Gas-liquid reactor 21 Process liquid level 22 Reactor Shell 30 serially arranged gas introduction units 31 Module Coupling

Claims

1. A gas introduction unit (10) for introducing a process gas into a liquid present in a reactor (20) without bubbles, the gas introduction unit (10) comprising: a first gas receiving chamber (1) for receiving a process gas, and a second gas receiving chamber (1) for receiving a process gas spaced apart from the first gas receiving chamber (1), the first gas receiving chamber (1) and the second gas receiving chamber (1) being connected to each other via at least two two-dimensional gas-conductive diffusion membranes (6) made of hollow fibers (6) spaced apart from each other and at least partially fixed to each other; a receptacle (4) for supplying gas provided in at least one of the gas receiving chambers (1); a receptacle (4) for a shaft (9) provided in at least one of the gas receiving chambers (1), A gas introduction unit (10) for introducing gas into the liquid in the reactor (20) can supply process gas through a gas supply receptacle (4) and can rotate through the receptacle (4) for the shaft (9), and can form convection in the reactor (20) through the rotational movement of the gas introduction unit (10) in the liquid.

2. 2. The gas introduction unit according to claim 1, wherein the projection of the diffusion membrane (6) onto the gas receiving chamber (1) has an arcuate shape.

3. 3. A gas introduction unit according to claim 1 or 2, wherein the receptacle (4) for the gas supply and the receptacle (4) for the shaft (9) are arranged in only one gas receiving chamber (1).

4. The gas introduction unit according to any one of claims 1 to 3, wherein the two gas receiving chambers (1) are each cylindrical and connected to each other via one or more mechanical supports (12).

5. 5. The gas introduction unit according to claim 4, wherein at least one retaining disk (7) is arranged between the two gas receiving chambers (1) on the mechanical support (12), the retaining disk being configured to mechanically retain the diffusion membrane (6).

6. 6. A gas introduction unit according to claim 4 or 5, wherein the mechanical support (12) is adapted to transport process gas from the gas receiving chamber (1).

7. 7. The gas introduction unit according to claim 1, wherein the ratio of the cross-sectional area of ​​the entire hollow fiber to the cross-sectional area of ​​the gas receiving chamber is 5% or more and 45% or less.

8. 8. The gas introduction unit according to claim 1, wherein the packing density of the diffusion membrane (6) relative to the volume of the gas introduction unit (10), expressed as the surface area of ​​the hollow fibers divided by the volume of the gas introduction unit (10), is 0.1 cm or more and 7.5 cm or less.

9. 9. A method for introducing a gas into a process liquid in a reactor (20), characterized in that the gas is introduced by a gas introduction unit (10) according to any one of claims 1 to 8.

10. 10. The gas introduction method according to claim 9, wherein the rotation speed of the membrane surface (6) at the outermost edge of the gas introduction unit (10) is 0.1 m / s or more and 5 m / s or less.

11. A gas-liquid reactor (20) comprising at least an outer reactor shell (22), a drive, a gas supply (9) and a gas introduction unit (10) according to any one of claims 1 to 8.

12. 12. The gas-liquid reactor (20) according to claim 11, wherein the reactor (20) does not include any stirring unit other than the gas introduction unit (10).

13. 13. The gas-liquid reactor according to claim 12, wherein at least one flow breaker (8) is arranged between the reactor shell (22) and the gas receiving chamber (1).

14. Use of a gas-liquid reactor (20) according to any one of claims 11 to 13 for supplying a process gas to a biological culture suspended in a process solution or for attaching the reactor interior or the gas introduction unit.

15. The use of claim 14, wherein the biological culture is adapted to produce a foam-forming substance.

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