DE2423766A1 - FERMENTATION PROCESS AND DEVICE FOR IMPLEMENTING IT - Google Patents

Description

Patent attorneys:

Dipl.-Ing. Tiedtke
Dipl.-Chem. "Biihling
Dipl.-Ing. Chins

8 Munich 2

Bavariaring 4, PO Box 202403

Tel .: (089) 539653-56
Telex: 524845 tipat
cable address: Germaniapatent Munich

Munich, October 1, 1974 Patent application P 24 23 766.9 B 6034 / ICI case B.26139

Imperial Chemical Industries Limited
London, UK

(Addition to patent application P 21 35 762.0)

Fermentation process as well as device too
its implementation

The invention relates to a fermentation process for
aerobic fermentation of a substrate by microorganisms which are able to use the substrate for growth and a fermentation device for carrying out this process and is a further development of the process and the device according to patent .... (patent application P 21 35 762.0).

Reactions that create intimate contact between a: gas and a liquid, for example aerobic fermentations, have heretofore been common for industrial applications been carried out in devices that "essentially

ii / i ₂

Deutsche Bank (Munich) Account 51/61070

409888/1218

chen have a large liquid container, in whose base or near the base gas is injected, An intimate contact between the gas and the liquid is achieved in that the liquid by means of mechanical Agitators or by forcing gas into the liquid or by a combination of these processes evenly circulated will. If the circulation process is effected by forcing in gas, the circulation pattern is a relatively rapid one ascending phase and a slower descending phase. In fermentations carried out in this way, the oxygen supplied to the liquid culture during the relative short ascending phase, whereas during the long descending phase the liquid culture is exposed to anaerobic or almost anaerobic conditions.

Industrial progress in general and developments in the field of industrial fermentations in particular including new processes for the production of proteins and other fermentation products lead to an increased Extent of required actions and make the effort required by facilities with greater capacity. It is not possible to adapt the above-mentioned devices to modern requirements adapt in a satisfactory manner as it is economical for various physical and biological reasons it is not feasible to enlarge the dimensions of the containers beyond certain limit values.

409386/1218

- j-

In fermentations that require a high level of oxygen supply, it is especially when using mechanical ones Difficult and expensive agitators, the necessary amount of air or other oxygen-containing during the process To supply gas and the various required properties of the liquid KuItür to be circulated at all points of the container constant and to keep the liquid culture continuously at a suitable and constant temperature. This requires a limit on the maximum volume of the container, what in order to maintain an economically producible container shape in general also to limit the height of the container (usually at about 15 meters).

In recent years, much attention has been paid to methods involving monocellular protein food additives by growing microorganisms on inexpensive raw materials based on substrates containing cheap carbon sources v / earth. Such processes require a high level of oxygen supply, especially when the microorganism is growing occurs at a high growth rate, and if a substrate is used for which the oxygen requirement by the microorganism is high, e.g. B. a hydrocarbon compound or a partially oxidized hydrocarbon compound. To make the product made in such a process economically competitive with the more conventional food materials To make it necessary to fermentation on a large scale and in a correspondingly large facility

409886/1218

perform. An economically successful workflow requires that a high degree of transfer of oxygen into the liquid culture be achieved during the process in order to produce a Fermentation device of a given volume the high oxygen requirement of fast-growing cultures with large-volume cells. That in conventional fermentation devices Oxygen transition degree achievable with normal dimensions is a commercially successful one Carrying out such a process is unsatisfactory.

In GB-PS 1 353 008 of the applicant is a method for the aerobic fermentation of a substrate by microorganisms described which is suitable, the substrate for growth to use, in which the fermentation medium comprising the substrate and the microorganisms continuously between two different hydrostatic pressures having areas is circulated, and in the area of higher hydrostatic pressure air and / or oxygen in the fermentation medium is dissolved and generated in the lower area lower hydrostatic pressure during the fermentation process Carbon dioxide leaves the fermentation medium.

In GB-PS 1 353 003 there is also a fermentation device with two tanks (a rising tank and a falling tank) and devices for generating a continuous one Circulation of the medium to be fermented between the two

409686/1219

the containers described, in which still in the vicinity of the lower end of a container (the rising container) means for feeding a gas into the fermentation device and to generate a pressure difference between the hydrostatic Press on the lower ends of the two containers in the event that the fermentation device contains a medium to be fermented .contains, are provided, and the pressure difference is sufficient is to ensure a continuous circulation of the medium to be fermented between two areas with different hydrostatic To effect pressing, and the apparatus further includes means for the escape of the gas from the upper part of the fermentation apparatus having.

The invention described in GB-PS 1 353 008 can be used for Fermentation processes carried out on a large scale can be used, as this is a transfer of oxygen to the liquid High degree of transition culture can be achieved without being compared to the conventional fermentation devices described above a corresponding increase in energy consumption takes place.

It has now been found that the results are satisfactory (in relation to the degree of oxygen transfer, the energy transfer ratio and the growth of microorganisms) can be achieved when performing the process according to GB-PS 1 353 008 the fermentation device exceeds a certain height and certain dimensions of the climbing

409886 / 121.8

- D

line and the downpipe relative to each other, and certain conditions for the gas supply, in particular the Air supply.

According to the present invention is a method of making contact between a liquid and a Gas provided, in which the liquid is continuously in a at least 20 meters high, at least one for the ascending Flow (hereinafter called riser) provided chamber and at least one for the descending flow (hereinafter referred to as downpipe) provided chamber having arrangement is circulated, and the entire usable cross section area of the riser (s) is between three and eight times as large as the total usable cross-sectional area the downpipe (s) and the upper and lower ends of the downpipe (s) are connected to the upper and lower ends, respectively, of the riser pipe (s), and the circulation of the liquid through the arrangement is carried out by injecting a gas into the assembly in such an amount that the liquid in the riser or the risers are given an average speed of at least 15 cm / sec.

A method for production is also according to the invention a contact between a liquid and a gas is provided, in which the liquid is constantly in at least a 20 Meter-high arrangement is rolled over, and the arrangement at least a chamber for the ascending flow (hereinafter

409888/1213

Called riser) and at least one chamber for the descending flow (hereinafter called downpipe), and the total usable cross-sectional area of the downpipe (s) is smaller than the total usable cross-sectional area of the riser (s) and the upper and lower ends of the downpipe (s) ) are connected to the upper and lower ends of the riser (s) * and the liquid in the arrangement is circulated by injecting a gas into the arrangement at a plurality of points distributed around the arrangement, and the points distributed around the arrangement in a sufficient amount are provided to give the liquid in the riser or in the risers a velocity of at least 15 cm / sec, and a portion of the order of between 10% and 100 % of the gas, preferably 10 % to 60 % of the Total volume of the gas into which the liquid is injected in the downpipe or in the downpipes.

Furthermore, according to the invention, a fermentation device is provided in which a liquid culture is continuously carried out Injection of a gas is circulated, which has a height of at least 20 meters and at least one chamber for the ascending Flow (hereinafter referred to as riser) and at least one chamber for the descending flow (hereinafter Called downpipe), and the total usable cross-sectional area of the riser (s) is between three and eight times as large like the total usable cross-sectional area of the trap (s), and the upper and lower ends of the downpipe (s) with the upper

409886/1218

ren or lower end of the riser (s) are connected, and means for injecting a sufficient amount of gas are provided in the arrangement to the liquid in the riser or risers a speed of at least 15cm / sec.

Furthermore, according to the invention, a fermentation device is provided for continuously circulating a liquid culture by injecting a gas, which has a height of at least 20 meters and at least one chamber for the ascending flow (hereinafter referred to as riser) and at least one chamber for the descending flow (hereinafter referred to as downpipe ), and the total usable cross-sectional area of the downpipe (s) is less than the total usable cross-sectional area of the riser (s) and the upper and lower ends of the riser (s) are connected to the upper and lower ends of the downpipe (s), respectively , and means for injecting a gas into the liquid culture are provided in the riser or the risers, and means for injecting one in the order of 10 to 100%, preferably between 10 and 60 % of the total amount of the gas injected into the culture the downpipe (s) are provided, and the Eet The amount of gas injected into the arrangement is sufficient to give the liquid in the riser or in the risers an average speed of at least 15 cm / sec.

409886/1218

Zv / corner wise, during the beginning of the invention In the process, all or most of the gas is injected into the riser pipe (s) for a while let the liquid begin to circulate. This startup process ^ continues until the liquid has reached a suitable degree of circulation, d. H. until the average speed the liquid in the downpipe or downpipes is at least 100 cm / sec.

The invention is generally applicable to processes in which there is intimate contact between a gas and a liquid must take place, for example in hydrometallurgical processes in the production of copper sulfate solutions Mineral ores containing copper sulphides. In this case, powdery, Ground ore dissolved in an aqueous medium is rapidly circulated, whereby the forced-in air also serves as a source of oxygen for the conversion the copper sulfide in the ore contained in the solution Copper sulfate is used. The conversion came about through the action of microorganisms present in the medium or through a simple one chemical process without the presence of microorganisms. The invention is particularly suitable however, for fermentation processes, especially for carrying out aerobic fermentations with a high acidity. material acquisition is required, albeit using the invention anaerobic reactions or fermentations can also be carried out by introducing a suitable gas into the arrangement

409836/1218

voltage is pressed in. AeroMsche fermentation processes, for which the invention is particularly useful include the production of unicellular proteins by microorganism growth Hydrocarbon or partially oxidized (e.g., methanol containing) hydrocarbon substrates or the Production of amino acids (e.g. lysine, glutamic acid or methiomine) or the production of citric acid and enzymes (e.g. isomeric glucose) or the manufacture of antibiotics (e.g. penicillin). Although the invention is not directed to an aerobic Fermentation process is limited, the following takes place Description using the technical terms for such a method. The term average speed the liquid or the liquid culture in the riser or the risers or the downpipe or the Downpipes in the following description means the Average velocity of the liquid or liquid culture in the riser (s) or Downpipe or downpipes, measured over the entire cross-section of the chamber. Since the inner cross-sectional areas of this Chambers, especially those of the risers, do not have to be the same over their entire length, the speed can change the liquid or liquid culture in each chamber as seen along its length change.

In one carried out according to the method according to the invention The aerobic fermentation process turns the entire circulating medium into the liquid culture by forcing gas into it

409186/1218

converted into a fluid of lower density, which is composed of gas bubbles, liquid and microorganisms. Through the volume difference resulting from the injected gas Between the riser and the downpipe, this fluid is given a speed that would be expected under normal working conditions is sufficiently large to have a completely "homogeneous distribution." to reach the bubbles. In this type the liquid culture in the assembly circulates essentially in a plug flow, d. H. in a plug flow with a certain amount of turbulent mixing.

During the process, all volume constituents of the liquid culture are circulated rapidly and evenly between areas of high and low hydrostatic pressure in the lower and higher parts of the assembly, respectively. In the high pressure area, the oxygen required for the growth of the microorganisms is absorbed by the culture, while in the area with lower pressure the CO ₂ generated during the process is desorbed. In the upper part of the arrangement, the released gas is released from the circulating liquid culture and can escape.

The degree of oxygen transfer into the liquid culture that can be achieved in an aerobic fermentation process is an important one Factor, since it is the degree of production of microorganisms that can be achieved in a fermentation device with a given volume is determined. In a large-scale

409886/1218

During the process, the degree of transition is at least 2 kg op / m h and is more in the range of 4 to 12 kg op / m h. Since the degree of transmission depends, among other things, on the total height of the arrangement, if a suitable degree of microbial growth and process productivity is to be present, it is important that the levels exceed a minimum value should. In the fermentation device according to the invention can a suitable degree of transmission can be achieved if the total height is 20 meters. However, there will be heights of at least 30 meters preferred, especially heights of 40 to 60 meters.

The pressed into the assembly during aerobic F _e rmentationsvorganges gas which may be oxygen, air or another oxygen-containing gas mixture, serves several purposes:

1. It causes the culture to circulate in the arrangement.

2. It provides the oxygen required by the microorganisms.

3. By a suitable choice of the points for the gas supply and the proportions of the gas to be injected at different points Gases, a control function can be exercised over the process to a considerable extent. In particular the flow rate and thus the circulation time of the medium can be controlled. In addition, the

409886/1218

AS

Concentration distribution of dissolved oxygen can be controlled.

4. The surface of the bubbles generated by the injected gas can be used for the desorption of the COp. The volume and composition of the injected gas can be used to control the distribution of the (XU concentration in the liquid or in the liquid culture.

The total amount of the pressed-in gas, the points at the pressing de NEN occurs and the ratio values of the pressed-in at the different sites amounts will vary in dependence on the conditional by the microorganisms requirements and to the respectively required degree of agitation.

The gas can be pressed into the downpipe (s) in one level or in a plurality of levels, for example 2 to 5 . The gas is preferably injected into the riser line (s) at one level, although it is also possible to inject gas into the riser line (s) at a plurality of level levels. Appropriate locations for injecting the gas into each chamber are distributed along the downcomer (s), but are concentrated at the base or near the base of the riser or risers.

In some embodiments of the device according to the invention, where the trap (s) and the riser (s) completely

409886/1218

are arranged separately from one another and connected to one another at their upper and lower ends via pipes, the gas provided for the riser can be pressed into the lower connecting pipe, which for this purpose can be regarded as part of the riser (s). In this case the lower connecting pipe is preferably angled upwards towards the main part of the riser pipe (s). For an easy start of the method according to the invention, a special gas feed is provided through which gas can be forced into the upper part of the riser line (s). The preferred ratio of the gas injected into the downcomer (s) is between 20 % and 40 % of the total amount of gas injected into the arrangement.

The geometric arrangement of the fermentation device can, as can be seen from the drawing, vary within wide ranges. A suitable design consists in that the riser (s) and the downcomer (s) are each arranged outside of one another and are completely separated from each other except for connecting pipes at their upper and lower ends. The arrangement can also be inside a single vessel can be provided, which ± m inside by one or more partition walls with openings at the top and lower ends is separated. The riser (s) and downcomer (s) can each be arranged outside of one another, be cylinders connected by pipes. The tubes can be arranged horizontally, or, in the case of the lower connection, a U-shaped Exhibit design. Another possibility is that the arrangement has, for example, two coaxial chambers,

409886/1218

one of which, preferably the riser, surrounds the other. The arrangement preferably has a plurality of each arranged outside a single downpipe and with this connected risers. In particular, 3 to 8 risers can be connected to a single downpipe be.

In this last-mentioned case, each individual riser have the same cross-sectional area as the downpipe, so that the cross-sectional areas of the risers as a whole are bigger. Such an arrangement can be supplied prefabricated.

The from the liquid culture in the downpipe or in the downpipes and in the riser or /. The speeds assumed in the risers depend on the cross-sectional areas of these chambers, that is to say, in the case of a cylindrical configuration, on their diameters. The chambers need not be of uniform diameter over their entire length, and it is sometimes even desirable that the riser (s) are formed in two vertically stacked sections, of which the lower section has a larger cross-sectional area. In this case the size of the cross-sectional area of the lower section of the riser (s) is preferably approximately three to eight times the size of the cross-sectional area of the upper section. The lower section preferably extends over 30 % to 60 % of the total length of the riser. In further training, there can be

409886/1218

4b

hen. be that the cross-sectional area of the Steigleitimg (s) with increasing height decreases evenly.

To avoid the accumulation of large amounts of COp, the liquid culture between the high pressure and. Low pressure areas the fermenter quickly circulated. The for a complete UmwäIzVorgang the liquid culture in the The time required for arrangement is between 0.5 and 5 minutes, preferably between 1 and 3 minutes. The speed of the liquid culture in any part of the riser (s) or the downcomer (s) depends on the cross-sectional area of the respective Part of the chamber. Since the liquid culture is to be circulated essentially in a plug flow, the minimum velocity must be in the riser or in the risers are more than 10cm / sec. Preferably the average speed is between 20 and 50 cm / sec in the riser or risers (in the lower area, if this Chamber does not have a uniform cross-sectional area) and between 200 to 500 cm / sec in the downpipe or downpipes.

The fermentation device can be operated either in cycles or take place continuously.

The liquid culture circulates essentially in a laminar flow, which enables a high degree of homogeneity to reach. Almost the entire volume of the fermentation

409886/1218

direction can be used for the growth of microorganisms, and areas where anaerobic conditions prevail, are avoided. This enables a high degree of influence on the fermentation parameters, such as the temperature, the pH value and the substrate concentration to be achieved, whereby an improved and more uniform Product can be generated. For example, when the method according to the invention is used for the production of unicellular proteins becomes, the generated microorganisms show a high degree of morphological uniformity, and it becomes an improved one Transition from substrate carbon to cellulose achieved. The invention enables effective circulation and ver avoids the use of external loop-shaped lines to dissipate the heat of reaction and fermentation.

In the case of aerobic fermentation, the invention brings good results with regard to the degree of oxygen transfer that can be achieved and energy consumption. The results to be achieved from experimental determinations and the calculations based on them Results are presented below.

For the fermentation apparatus shown in Fig. 1, the oxygen transfer rate and the energy transfer ratio calculated.

The degree of oxygen transfer is the amount in kilograms Op per hour and meter of liquid under which it is located

409888/1218

Dissolves oxygen in the liquid culture.

The energy transfer ratio is the ratio of oxygen transfer to energy consumption, expressed as kilograms 0 _{? Dissolved in the liquid culture.} per kilowatt hour of 'work expended in compressing the air before injecting it into the liquid culture. The energy transfer ratio decreases as the degree of transfer increases. For an economical operation of a fermentation device it is desirable that both parameters should be as large as possible.

The calculations were carried out using equations for the gas transfer (particularly oxygen and C0 _? ) Between the gas bubbles and the liquid culture. Furthermore, the pressure changes between the different parts of the arrangement were taken into account in the calculation.

The energy required for gas compression was below calculated using the following assumptions:

1. The pressure in the upper part of the assembly (where the gas separation takes place) is 1.5 bar absolute.

2. The pressure loss between the compressor and the inlet the fermentation device is 1 bar.

3. Air is used as the oxygen-supplying gas with an inlet pressure of 1 bar and a temperature of

409886/1218

⁴ *

Assumed 20 ° C. The compression process is said to be adiabatic (isentropic) and result in a pressure increase that is suitable for overcoming the assumed loss of 1 bar. Air is (or the Einpreßpunkte'n.) Through the at the Einpreßpunkt ^(or. Present Drükken) existing pressure are pressed.

These assumptions lead to an estimated compression work that is realistic with regard to the shaft output powers of large axial compressors with intermediate cooling between two stages. It was assumed that up to 45 % of the gas is injected into the fail line at up to 3 points.

The results obtained are shown in the table.

Degree of transmission of
Oxygen to that
Medium,
(kg / hm <) Energy trans
supply ratio
(kg / KWh) Height of fer
mentiervor
direction
(m) 2 2.7 20th 6th 3.0 30th d - 2.7 40 10 2.5 50 12th 2.3 60 14th . 2.1 70 16 1.9 80

409886/1218

The calculation of the table was made with careful assumptions regarding the mass transfer coefficient and the Average Bubble Size - From the table it can be seen that the degree of oxygen transfer increases with the height of the fermenter grows. The best results previously achieved with known fermentation devices were to the best of our knowledge the inventor at transmission rates of about 3kg per hour per m of liquid culture and were only at lower Energy transfer ratios obtained than can be achieved with the present invention. Thus, the Results known to the inventors to date are significantly improved by the fermentation device according to the invention. It is It can be seen that the height of the fermenter is of importance in obtaining this improvement.

It should be noted that an even higher degree of oxygen transfer can be achieved when the oxygen supplying gas using pure oxygen or a Mixture of pure oxygen with air is enriched. This method does not constitute a peculiarity of the present invention but can easily be used in combination with this. In a similar way, an increase in the degree of transmission can be achieved by building the entire fermentation device as a pressure vessel so that the pressure is above the surrounding atmospheric pressure is raised. It is possible to combine this method with the present invention as well. But these two well-known methods of increasing the transmission

409886/1218

Efficiency levels, particularly the use of pure oxygen or a total internal overpressure, also have disadvantages, as is known to those skilled in the art. A particular advantage of vorlie- l · constricting invention is that with air as sauerstofflieferndem gas transfer rates that are so high; as shown in the table, can be achieved with a good energy transfer ratio without raising the concentration of the CO 2 dissolved in the liquid culture to a high level.

The invention is described below .anhand the accompanying drawings described. Show it:

Fig. 1 is a partially sectioned side view of a Fermentation device in which the riser and the downpipe are each arranged outside of one another are;

Fig. 2 is a partially sectioned side view of a Fermentation device in which the riser and the downpipes are arranged coaxially; ·, and at which the riser is annular in cross section;

3 shows a further exemplary embodiment of the fermentation device shown in FIG. 2, in which the riser is circular in cross section;

Fig. 4 .. a partially in section * held side view of a Fermentation device in which the cross-sectional area

409886/1210

before the riser over the length of the fermenter seen is constant;

.Fig. Figure 5 is a side view, partly in section a further embodiment of the fermentation device shown in Fig. 4, in which the riser, is circular in cross section;

FIG. 6 shows a sectional view along the line x-x in FIG. 6a through a further exemplary embodiment of the in Fig. 1 shown fermentation device, in which a plurality of risers is provided, and the risers along the length of the fermenter seen have a constant cross-sectional area.

FIG. 6a shows a plan view of the ferment shown in FIG. 6 iervor direction;

FIG. 7 shows a section along the line x-x in FIG. 7A through a further exemplary embodiment of the one shown in FIG. 1 Fermentation apparatus in which a plurality of risers are provided;

Fig. 7A is a top plan view of the "below line Y-Y in Fig. 7 shown fermentation device.

For the sake of clarity, only FIG. 1 shows a suitable position for a heat exchanger intended for this purpose is to dissipate fermentation heat or the

400886/1218

- 23 mixed reaction. To dissipate or supply required heat.

The fermentation processes shown in FIGS. 1, 2, 3 and 7 directions have a riser or risers, the connected via a reducer 3 cylindrical or ring-shaped have upper and lower sections 1 and 2 respectively. The lower section 2 has a larger diameter than the upper section 1.

The fermentation devices shown in FIGS. 4, 5 and 6 have a riser pipe or risers 4 which are cylindrical or ring-shaped and have a constant cross-sectional area.

The top of the riser is connected to the top of the Downpipe 5 connected via a connecting piece 6, which, as shown in FIGS. 1, 6 and 7, is arranged horizontally and cylindrical may be formed, or have a vertical cylindrical section 7 and conical connecting pieces 8 and 9 can, which, as shown in FIGS. 2, 3, 4 and 5, form an extension of the riser or the downpipe.

The lower end of the riser is connected to the lower end of the downpipe via a connector 10 which, as shown in FIGS. 1, 6 and 7, can be cylindrical, or, as shown in FIGS. 2, 3, 4 and 5, horizontal can be designed ring-shaped and can form the basis of the Fermen animal device. ι

409888/1218

In the lower section of the riser is through sprinkler pipes 11 a gas, for example air, is sprayed in, which causes a continuous circulation of the liquid, the Fermentiervorrich- ι tion up to the level A-A causes filling phase. The upper connection piece 6 must not be completely filled with liquid, so that a free surface is created on which gas bubbles escape from the liquid and through an opening 12 can flow off.

By a sprinkler pipe 13 or a plurality of sprinkler pipes 13, of which two in each case in FIGS are shown, additional gas, for example air, is supplied to the downpipe. A delivery medium which contains the constituents essential for fermentation, enters the fermentation device through a pipe 14, and the culture is removed from the fermenter through a tube 15. In the ascending section are devices for Breaking up the bubbles, such as 16, is provided. In Fig. 1, the heat exchanger 7 is shown in the downpipe 5, although it is possible to arrange the heat exchanger at any point in the riser or the downpipe. It exists also the possibility of a plurality of devices for heat exchange either in the rising section or in the falling section or to be arranged in both.

409886/1218

Claims (14)

SUBSEQUENT Patent attorneys: Dipl.-Ing. Tiedtke Dipl.-Chem. Bühling Dipl.-Ing. Kinne 8 Munich 2 Bavariaring 4, Postfach 202403 Tel.:(089)539653-56 Telex: 524 845 tipat cable address: Germaniapatent Munich Munich, October 1st. 1974 Patent application P 24 23 766.9 Imperial Chemical Industries, Ltd, B 6034 / ICI case B.26139 claims 1. Fermentation process for aerobic fermentation of a substrate by microorganisms ^ which are able to to utilize the substrate for growth according to patent (Patent application P 21 35 762.0), characterized in that the fermenter consisting of the substrate and the microorganisms medium continuously at a height of at least 20 meters Arrangement with at least one for the ascending flow (hereinafter referred to as riser) provided, and at least a chamber provided for the descending flow (hereinafter referred to as downpipe) is circulated, and the entire usable chamber Cross-sectional area of the riser (s) is between 3 and 8 times as large as the total usable cross-sectional area of the downpipe (s), and the upper and lower ends of the downcomer (s) connected to the upper and lower ends of the riser (s), respectively are, and the circulation of the medium through the arrangement by forcing a gas in such an amount into the ^{/ 12} 409886/1218 Deutsche Bank (Munich) KIo. 51/51070 Dresdner B.nk (Munich) Account 3839844 Po · »* · * (Münch.n) Account 670« -804 SUBSCRIBED - 2fr- The flow is carried out, the liquid is in the riser or in the the risers are given an average speed of at least 15 cm / sec. 2. Another embodiment of the fermentation process according to claim 1, characterized in that the medium is constantly circulated in an arrangement at least 20 m high, and the arrangement of at least one chamber for the ascending flow (hereinafter referred to as the riser) and at least one chamber for the descending flow (hereinafter referred to as Fallleitüng), and the entire usable cross-sectional area of the downpipe (s) is less than the total usable cross-sectional area of the riser (s), and the top and bottom ends the fall line (s) with the upper and lower ends of the riser (s) are connected, and the circulation of the medium in the arrangement by forcing gas into the arrangement at one A plurality of points distributed around the arrangement takes place, and the points distributed around the arrangement in a sufficient quantity are present in order to give the medium in the riser or in the risers a speed of at least 15 cm / sec grant, and a portion of the order of magnitude between 10% and 10% of the total amount pressed into the arrangement Gas is pressed into the medium in the Fallleitüng or in the downpipes. 3. The method according to claim 1 or?, Characterized in that the medium is a liquid consisting of a 409886/121 8 Culture containing microorganisms is, and the gas is an oxygen containing gas. 4. The method according to any one of claims 1 to 3, characterized in that that the height of the arrangement is between 40 and 60 meters. 5. The method according to one of the claims 1 to 4, thereby characterized in that the injection of the gas takes place at 1 to 5 different height levels. 6. The method according to any one of claims 1 to 5, characterized in that between 10 % and 60 % of the total amount of the gas injected into the arrangement is injected into the liquid in the downpipe or pipes. 7. The method according to any one of claims 1 to 6, characterized in that that the arrangement three to eight each arranged outside of a single downpipe and connected to this Has risers. 8. The method according to any one of claims 1 to 7, characterized in that that the average velocity of the liquid in the riser or in the risers between and 80cm / sec. 409 886/1218 it 9. The method according to any one of claims 1 to 8, characterized characterized in that the average velocity of the liquid in the downpipe or in the downpipes is between 200 and 500cm / sec. 10. Fermentation device for carrying out the process according to claims 1 to 9, characterized in that the device has a height of at least 20 meters, and at least one chamber (4) for the ascending flow (hereinafter referred to as the riser) and at least one chamber (5) are intended for the descending flow (hereinafter referred to as downpipe), and the total usable cross-sectional area of the riser (s) (4) between three and eight times as much is as large as the total usable cross-sectional area of the downpipe (s) (5), and the upper and lower ends of the riser (s) (4) with the upper and lower ends of the downcomer (s), respectively (5) are connected, and means (11, 13) are provided for injecting a sufficient amount of gas into the arrangement are to the liquid in the riser (4) or the risers (4) to a speed of at least 15 cm / sec To give. 11. Another embodiment of the fermentation device for performing the method according to claims 1 to 9, characterized in that the device has a height of at least 20 meters, and at least one chamber (4) for the ascending flow (hereinafter referred to as the riser) and at least one chamber (5) for the descending 409886/1218 Flow (hereinafter referred to as company management) are provided / and the total usable cross-sectional area of the downpipe (s) (5) is smaller than the total nutsbar * üuschnittsflache of the riser (s) (4), and the upper and lower ends of the riser (s) (4) with the upper and lower ends of the downpipe (s) (5) are connected, and devices (11) for injecting a gas into the liquid culture in the riser (4) or in the risers (4) and devices (I ₃ ) for Injection of a portion of the order of magnitude of 10% to 100% of the total amount des.einepreßten gas into the culture in the downpipe (5) or in the downpipes (5) are provided, and the amount of gas injected into the arrangement is sufficient to remove the liquid in the riser (4) or in the risers (4) give an average speed of at least 15cm / sec. 12. Fermentation device according to claim 10 or 11, characterized characterized in that the device has a height of 40 to Meters. 13. Fermentation device according to one of claims 10 to 12, characterized in that the devices (13) for pressing of gas in the downpipe (s) (5) on in one to five different heights provided places * nf « are. 409886/1218 14. Fermentation device according to one of claims 10 to 13, characterized in that three to eight risers (4) are provided, which are arranged outside a single downpipe {5) and connected to this. 409886/1218