FR2507500A1 - Rotary agitator - aerator partic for prodn. of metabolites etc. - using rotor contg. air compressing piston reciprocated by eccentric - Google Patents

Abstract

The rotor is mounted on a motor-driven shaft. As the rotor turns it draws in external air via a passage through the shaft, compresses the air and then diffuses it into the agitated liq. in the vessel. Pref. the rotor contains a cylindrical chamber in which a piston is reciprocated by shaft rotation. The piston is reciprocated by an eccentric rigidly fixed to the shaft. The eccentric has a cutout extending from the air inlet passage to the circumference of the eccentric over a substantial arc. The cutout rotates to communicate alternately with axial air discharge passage through opposite ends of the piston. As the piston reciprocates, its retreating face sucks air into the cylinder via shaft passage and cutout; its advancing face expels air from the other end of the cylinder via a valved outlet nozzle. The axis of the eccentric is pref. offset from the parallel axis of the drive shaft by a distance equal to half the dia. of the drive shaft. The installation is esp. employed in the mfr. of metabolites such as enzymes or organic acids such as citric, by aerobic fermentation of a liq. nutrient inoculated with suitable microorganisms. It is also applicable to the purificn. of waste water. Aeration takes place at the point of most intense agitation. Aeration is automatically proportional to the rate of agitation. No separate compressor is required to inject the air.

Description

 The present invention relates to a device for agitating and aerating a liquid contained in a container.

 The invention also relates to an installation comprising such a device, in particular for the manufacture of metabolites such as enzymes or organic acids such as for example citric acid, by aerobic fermentation of a nutritive liquid inoculated with an appropriate micrororganism .

 Such an installation can also be used to regenerate waste water by agitation and aeration.

 In known fermenters, the nutrient liquid loaded with microorganisms is continuously stirred by agitators driven in rotation by motors.

 The air necessary for fermentation is injected under pressure into these fermenters by compressors also driven in rotation by motors, these compressors being associated with complex means for adjusting the flow rate and injecting air.

 The motors used to control the stirring and the air injection require relatively high powers, which results in high energy expenditure.

 The object of the present invention is to remedy this drawback by creating a device for agitating and aerating a liquid, such as the nutritive liquid contained in a fermenter, this device being of simple construction, of economical use, and making it possible to obtain particularly effective agitation and aeration.

 The device intended by the invention for agitating and aerating a liquid contained in a container comprises at least one agitator mounted on a shaft driven in rotation by a motor, and means for introducing air into the liquid.

 According to the invention, this device is characterized in that the agitator comprises means making it possible, during its rotation, to aspirate the air outside the container, to compress this air and to atomize it within the liquid .

 Thus, the agitator, while being driven in rotation, sucks in air from the outside, compresses it and sprays it in the liquid.

 Therefore, not only is the aeration carried out at the stirring level, which is favorable for the good distribution of oxygen within the stirred liquid, but moreover, this aeration is regulated at the same time as the agitation, by acting on the speed of rotation of the agitator drive motor.

 In addition, significant savings are made by eliminating the air compressors driven in rotation by motors separate from those driving the agitators, as well as the flow control and air injection devices associated with these motors.

 According to an advantageous version of the device, the agitator comprises a body containing at least one piston driven by an alternating movement during the rotation of the agitator, and mounted in a sliding manner in a suction and compression chamber formed in this body, means being provided for successively controlling the admission of air inside the suction chamber, the compression of this air in this chamber and the exhaust of air by at least one outlet nozzle formed on the body of the agitator.

 The rotation of the shaft connected to the motor simultaneously causes the rotation of the agitator and the displacement of the piston which sucks in air from the outside, then compresses it by spraying it into the liquid of the container.

 According to a preferred version of the invention, the agitator drive shaft has a central channel which communicates with the outside air and which comprises a cam for controlling the rotation of the body, this cam having a recess which communicates with the central channel of the shaft and successively with the suction and compression chamber.

 In a particular embodiment of the invention, the piston has two opposite faces each delimiting with the adjacent end of the body, successively a suction chamber and a compression chamber, the cam of the drive shaft in rotation of the body having a cylindrical surface whose axis is offset from that of the shaft, this cylindrical surface being housed in a bore formed in the piston, the axis of this bore being perpendicular to the direction of movement of the piston and being a axis of symmetry of this piston, the symmetrical elements of the piston arranged on either side of this axis each comprising a conduit perpendicular to the bore, which opens into the suction or compression chamber and into the recess formed in the cam during the suction stroke of the piston.

 The invention also relates to an installation comprising a container containing a liquid intended to be stirred and ventilated, and comprising several devices in accordance with the invention, this installation being characterized in that these devices are distributed along the height of the container.

 These devices thus make it possible to carry out stirring and aeration regularly distributed throughout the liquid contained in the container.

 The stirring and aeration conditions are further improved when each device comprises several agitators fixed on a common rotary drive shaft.

 According to a preferred version, the installation comprises two series of devices distributed along the height of the container and arranged opposite one another, one of the series of these devices comprising rotation drive means comprising a pipe communicating with the upper part of the container and with pneumatic motors connected to the drive shaft in relation to the devices, this pipe taking the gases formed in the container in order to rotate the devices in a direction of rotation opposite to that of the available devices. located in the other series.

 Thus, the second series of devices is driven in rotation only by the exhaust gases taken from the top of the container, that is to say without an electric motor, which makes it possible to achieve considerable energy savings.

 In the case of the preparation of metabolites such as enzymes or organic acids, the installation makes it possible to obtain with minimum energy consumption, excellent yields due to the perfect conditions of agitation and aeration of the liquid. nutritious inoculated by an appropriate micro-organism.

 Other features and advantages of the invention will become apparent in the description below.

In the appended drawings, given by way of nonlimiting examples:
FIG. 1 is a schematic view in longitudinal section of an installation equipped with stirring and aeration devices according to the invention,
FIG. 2 is a view in longitudinal section of a device according to the invention,
FIG. 3 is a sectional view along the plane 111-111 of FIG. 2,
Figure 4 is a side view of the device
trans shaft and cut its drive shaft,
FIG. 5 is a view of one of the ends opposite the shaft of the device, after removal of the horn-shaped extension,
FIG. 6 is a variant of the installation, having a greater capacity than that of FIG. 1.

 In the embodiment of FIG. 1, the installation for the production of metabolites such as enzymes, proteins and organic acids such as, for example, citric acid, comprises a vertical cylindrical container 1 containing a nutritive liquid 2, inoculated by a micro- suitable organism for fermentation.

 This installation comprises three devices, 3, 3 a, 3 b, of agitation and aeration distributed according to the height of the container 1.

 Each device 3, 3 a, 3 b, comprises three agitators, 4, 4 a, 4 b, mounted on a common shaft 5, driven in rotation by a motor 6.

 Each agitator, 4, 4 a, 4 b, comprises means which will be detailed below, allowing during its rotation, to suck the air outside the container 1, via the pipe 7, and to spray this air into the nutritive liquid 2.

 In the embodiment shown in Figures 2 to 4, the agitator 4 comprises a body 8 containing a piston 9 driven by an alternating movement during the rotation of the agitator. This piston 9 is for this purpose mounted in a sliding manner in a suction and compression chamber 10, arranged inside the body 8, means being provided for successively controlling the admission of air into the chamber 10, then the compression of this air in this chamber and the exhaust of this air by outlet nozzles, 11, 12, formed on the ends 13, 14, of the body 8, opposite the shaft 15 for driving in rotation of agitator 4 (see Figures 2 and 3).

 The shaft 15 has a central channel 16, which communicates with the outside air to the container 1 via the pipe 7. This shaft has a cam 17 for controlling the rotation of the body 8. This cam 17 has an internal recess 18, which communicates with the channel 16 and successively with the suction and compression chamber 10, during the rotation of the shaft 15.

 The piston 9 comprises two symmetrical elements 9 a, 9 b, whose opposite faces 9 c, 9 d, each delimit with the adjacent ends, 13, 14, of the body 8, successively a suction and compression chamber 10.

 The cam 17 has a cylindrical surface 17 a, the axis YY of which is offset from the axis XX of the shaft 15, this cylindrical surface being housed in a bore 19 made in the piston 9. The axis YY of this bore 19 is perpendicular to the direction of movement of the piston 9 and is an axis of symmetry of the latter.

 The symmetrical elements, 9 a, 9 b, of the piston 9 each comprise a conduit 20 a, 20 b, perpendicular to the bore 19 and which opens into the chamber 10 for suction and compression. This conduit 20 a, or 20 b, also opens into the recess 18 formed in the cam 17 during the suction stroke of the elements 9 a, 9 b of the piston 9 (see FIG. 3).

The body 8 has on its two sides, 21 a, 21 b, adjacent to the shaft 15, two cylindrical bores 22 a, 22 b, whose common axis ZZ is parallel to the axis
XX of tree 15 and whose radius is equal to twice that of tree 15.

 The shaft 15 is tangent to these two bores 22 a, 22 b. The axis YY of the cam 17 is offset with respect to the axis XX of the shaft 15 at a distance d equal to half the radius of the shaft 15. FIG. 3 also shows that the axes XX, YY and ZZ are located in the same plane P.

In this FIG. 3, it can be seen on the other hand that the recess 18 of the train 17 is open towards the bore 19 of the piston 9 along an angular sector slightly less than 180 degrees so that when the axes XX
YY and ZZ are located on the sliding axis of the piston 9, the latter then being at the end of the stroke, as in the disc in FIGS. 2 and 3, the conduits 20 a and 20 b are closed simultaneously.

 FIG. 3 also shows that the bottom of the recess 18 has a convex surface opposite its opening, the top of this convex surface being located in the extension of the internal channel 16 of the shaft 15.

In the embodiment shown, the outlet nozzles 11, 12, formed on the opposite ends 13, 14, of the body 8, open inside the chamber 10,
by means of a valve opposite the pistons 9.

outlet nozzles 11, 12, are formed in horn-shaped extensions 23, 24, fixed on the ends 13, 14, of the body 8. As indicated in FIG. 3, these extensions 23, 24 are directed in a direction substantially perpendicular to the tree 15.

 Furthermore, it can be seen in FIG. 5 that the section of the piston 9 and of the body 8 is formed by cylindrical surface portions 25, 26, 27, centered on the plane of symmetry Q which is perpendicular to the shaft 15.

 We will now describe with reference to Figures 2 and 3, the operation of the stirring and aeration device according to the invention.

 The recess 18 of the cam 17 communicates permanently with the outside air through the channel 16 of the shaft 15. When this shaft is rotated about its axis XX along the arrow F (see FIG. 3), the cam 17 moves the piston 9 along the arrow F1 and at the same time the body 8 of the agitator is driven in rotation along the arrow F2 at a speed twice less than that of the shaft 15. This produces a reduction in speed. which generally avoids the use of a reduction box at the outlet of the motor 6.

 When the cam 17 rotates along arrow F, the recess 18 communicates with the conduit 20 b. The displacement of the piston 9 along the arrow F1 thus makes it possible to suck the air in the upper suction chamber 10 until the end of the piston stroke.

 When the piston 9 moves in the opposite direction (see arrow F3) the conduit 20 b is closed by the cylindrical surface of the cam 17, and the air contained in the upper chamber 10 is compressed and expelled into the liquid 2 by the nozzle 12.

 Consequently, the rotation of the agitator 4, the suction of the outside air, the compression of the latter and its exhaust in the guide guide 2 are carried out at the same time by either of the nozzles it or 12 and by the valve 20c or 20d.

 The expulsion of air inside the liquid 2 is thus perfectly synchronized with the rotation of the agitator.

 To increase or decrease the air flow and the stirring speed, it suffices to increase or decrease the speed of rotation of the motor 6.

 Furthermore, during the rotation of the stirrers, it forms in the vicinity of the latter a cavitation phenomenon favorable to the withdrawal of carbon dioxide contained in the liquid 2, and to the dissolution of oxygen in the solution.

 The device according to the invention therefore allows agitation and aeration to be perfectly controlled and regularly distributed in the liquid 2. In addition, the device according to the invention is particularly economical in energy.

 The liquid 2 penetrates inside the body 8 through the bores 22 a, 22 b and thus ensures the lubrication of the piston 9, which guarantees excellent reliability of the device.

 In the case of a container 1 of large width, it is advantageous to mount on the shaft 5 several devices 4, 4 a, 4 b, of agitation and aeration, as indicated in FIG. 1.

 In addition, taking into account the cylindrical shape of the container 1, the devices 4, 4 a, 4 b, advantageously have lengths which increase progressively from the outside towards the inside of the container.

On the other hand, it is preferable that the devices 4, 4 a, 4 b, are offset relative to the
of other agitators at an angle equal to 3600 / n, n being the number / to better balance the system and so that air exhausts through the outlet nozzles are not carried out simultaneously.

 The device according to the invention is particularly well suited to fermenters intended for the production of enzymes, proteins or organic acids.

 In such fermenters, the liquid 2 is a nutritive liquid containing an appropriate microorganism.

The good conditions of agitation and aeration make it possible to obtain optimal yields, while avoiding the degradation of the microorganism of inoculation.

 In the installation shown in FIG. 1, intended for example for the production of citric acid, the container 1 comprises a vertical partition 30 which separates this container into two separate compartments, 31, 32, one communicating with the other at the top and bottom of the container, and making it possible to carry out a circulation of liquid following a closed path.

The fermented liquid containing citric acid is taken from the bottom of the container 1 by a pipe 33 which is located under a filtering material 34, which has the effect of retaining the microorganisms inside the container.
This liquid is periodically recycled to the top of the container 1 through a pasteurizer 35.

 After periodic withdrawal of liquid through line 33, the container 1 is replenished with fresh nutritive liquid by the reservoir 36.

 In the case of a container 1 such as that shown in FIG. 1, and having a volume of the order of 250 cubic meters, three motors of 50 KW of power each are sufficient to operate the stirring devices and ventilation.

 In the installation shown in FIG. 6, the container 37 has a larger volume than that of FIG. 1. This container 37 comprises two series of stirring and aeration devices 38a, 38b, 38c, 38d and 39a, 39b, 39c, 39d, distributed along the height of the container, and arranged opposite one another.

 The devices 38a ... 38d, represented on the left of the figure, are driven normally in rotation by electric motors 40.

The series of devices 39a ... 39d, represented on the right of the figure, are driven in rotation by the exhaust gases taken from the top of the container 37 by the pipe 51. This pipe 51 communicates with pneumatic motors (53a, 53b, 53c, 53d) connected to the shafts 52a 52d for driving the devices in rotation. These pneumatic motors 53a ... 53d can be designed in the same way as the agitators 38a ... 38d.

 These exhaust gases, the pressure of which corresponds practically to that obtained by the air which is injected into the liquid by the devices 38a ... 38d, make it possible to rotate the devices 39a ... 39d in the opposite direction to those from the left.

 An energy saving of almost 50% is thus achieved.

 Of course, the invention is not limited to the examples just described, and many modifications can be made to them without departing from the scope of the invention.

 Thus, the device according to the invention can be used in any other application where it is necessary to agitate and aerate a liquid.

Therefore, the device according to the invention can be used for the regeneration of waste water and the oxygenation of lake or river water.
Furthermore, the agitators 4, 4a, 4b could be joined to each other to form a single assembly.

Claims (16)

 1. Device for agitating and aerating a liquid (2) contained in a container (1), comprising at least one agitator (4) mounted on a shaft (5, 15) driven in rotation by a motor (6) and means for introduce air into the liquid (2), characterized in that the agitator (4) comprises means making it possible, during its rotation, to suck the air inside the container (1), to compress this air and spray it into the liquid (2).  2. Device according to claim 1, characterized in that the agitator (4) comprises a body (8) containing at least one piston (9) driven by a reciprocating movement during the rotation of the agitator and mounted sliding way in a suction and compression chamber (10) arranged inside the body (8), means being provided for successively controlling the admission of air inside the chamber ( 10) suction, the admission of this air into the compression chamber, and the exhaust of air by at least one outlet nozzle (11, 12) formed on the body (8).  3. Device according to claim 2, characterized in that the shaft (15) driving the agitator (4) has a central channel (16) which communicates with the outside air and which comprises a cam (17 ) to control the rotation of the body (8), this cam (17) having a recess (18) which communicates with the central channel (16) of the shaft (15), and successively with the suction chamber (10) and compression.  4. Device according to claim 3, characterized in that the piston (9) has two opposite faces (9 c, 9 d) each delimiting with the adjacent ends (13, 14) of the body (8), successively a chamber ( 10) suction and compression, in that the cam (17) of the shaft (15) has a cylindrical surface (17 a) whose axis (YY) is offset from the axis (X- X ') of the shaft (15), this cylindrical surface being housed in a bore (19) formed in the piston (9), the axis of this bore being perpendicular to the direction of movement of the piston (9) and being an axis of symmetry of this piston, the symmetrical elements (9 a, 9 b) of the piston (9) arranged on either side of this axis, each comprising a conduit (2G a, 20 b) perpendicular to the bore (19) which opens into the suction or compression chamber (10), and into the recess (18) formed in the cam (17) during the suction stroke of the piston (9).  5. Device according to claim 4, characterized in that the body (8) has on its two opposite sides (21 a, 21 b) adjacent to the shaft (15) two cylindrical bores (22 a, 22 b) of which the common axis (ZZ) is parallel to that of the shaft, and whose radius is equal to twice that of the shaft, the latter being tangent to these two bores, and in that the axis (Y- Y ') of the cam (17) is offset with respect to the axis (XX) of the shaft (15) at a distance (d) equal to half the radius of the shaft, the axis (XX) of this shaft, the axis (YY) of the cam and the axis (ZZ) of the cylindrical bores (22 a, 22 b) being located in the same plane.  6. Device according to claim 5, characterized in that the recess (18) of the cam (17) is open towards the bore (19) of the piston (8) in an angular sector slightly less than 180 degrees, so that when the axis (YY) of the cam, the axis (XX) of the shaft, and the axis (ZZ) of the cylindrical bores, are located on the sliding axis of the piston (9), the conduits (20 a, 20 b) elements (9 a, 9 b) of the piston are closed simultaneously.  7. Device according to claim 6, characterized in that the bottom of the recess (18) has a convex surface (18 a) opposite its opening, the top of this convex surface being located substantially in the extension of the inner channel (16) of the tree (15).  8. Device according to any one of claims 4 to 7, characterized in that the body (8) has on each of its ends (13, 14) opposite the shaft (15) an outlet nozzle (11, 12) which opens into the interior of the suction and compression chamber of the piston (9) by means of a valve (20c, 20d) facing a conduit (20a, 20b) formed on each of the two elements of the piston, these nozzles being formed in extensions (23, 24) in the shape of a horn, fixed on the adjacent ends of the body (8).  9. Device according to claim 8, characterized in that the extensions (23, 24) in the shape of a horn, are directed in a direction substantially perpendicular to the shaft (15).  10. Installation comprising a container (1) containing a liquid (2) intended to be stirred and aerated, and comprising several devices (3, 3a, 3b) according to any one of claims 1 to 9, characterized in that these devices are distributed regularly according to the height of the container (1).  11. Installation according to claim 10, characterized in that each device comprises several agitators fixed on a common rotating drive shaft (5).  12. Installation according to claim 11, characterized in that the agitators are offset from one another at an angle equal to 3600 / n, n being the number of agitators.  13. Installation according to any one of claims 10 to 12, characterized in that it comprises two series of devices (38a ... 38d; 39a ... 39d) distributed regularly along the height of the container (37) and arranged opposite one another.  14. Installation according to claim 13, characterized in that, for one of the series of devices (39a ... 39d), the means for driving the agitators in rotation comprise a pipe (51) communicating with the upper part of the container (37) and with pneumatic motors (53a ... 53d) connected to the shaft (52a ... 52d) for driving the agitators in rotation, this pipe (51) taking the gases formed in the container ( 37) for driving the agitators in rotation in a direction of rotation opposite to that of the agitators of the other series (38a ... 38d).  15. Installation according to any one of claims 10 to 14, in particular intended for the manufacture of metabolites by aerobic fermentation of a nutritive liquid inoculated by an appropriate microorganism, characterized in that the container (1, 37) contains a vertical partition (30) which separates the container into two separate compartments (31, 32) communicating with each other at the top and bottom of the container, these compartments defining a closed path for the circulation of the nutritive liquid (2) contained in the container.  16. Installation according to claim 15, characterized in that the bottom of the container comprises a filtering material (34) which covers the orifice for taking the fermented liquid from the container.