DE3912613A1 - METHOD AND DEVICE FOR THE MULTI-STAGE, CYCLICALLY CONTINUOUS COUNTERFLOW CONTACTING OF A LIQUID PHASE AND A SOLID PHASE HAVING DIFFERENT DENSITY, AND / OR ONE NOT MIXABLE WITH THE FIRST LIQUID PHASE - Google Patents

Abstract

A sloping cascade (e.g. at 30 DEG to the horizontal) is composed of a series of stages of the construction illustrated. Attached to the mixing/settling vessel 2 by tube 4 is a separate vessel 3, at the top of which are valves 12a, for supplying compressed air, and 12b, for connection to the atmosphere. The phases in vessels 2 are agitated by means of gas supplied by lines 18. After the phases have settled, valves 12a are opened, in sequence, from the lowermost stage up. This causes the lighter phase to spill over, through lower connection 5, to the stage under it. Closing valve 12a, and opening 12b, restores the liquid to its former position. The heavy phase is discharged from the top stage by air-lift 22 and then, in succession, the heavy phase is moved up from each stage to the next higher, where it may be introduced into either of vessels 2 or 3. Mechanical agitation may be used; pumps may replace air-lifts 22; the lighter phase may be expelled by introducing the heavier below it. Both phases may be liquid, or one may be solid. Exemplified is treatment of a cation-exchange resin with sulphuric acid. <IMAGE>

Description

The invention relates to a method and a device for the multi-stage, cyclically continuous counterflow contacting a liquid phase and a solid phase, that have different density, and / or one with the first liquid phase cannot be mixed Liquid phase.

The countercurrent contacting of a liquid phase with a Solid phase, which is an un compared to the liquid phase has different density, and / or with a liquid phase se that does not mix with the first-mentioned liquid phase bar is of great importance for the execution of egg A large number of known processes that form three basic groups belong to, namely to operate units based on based on simultaneous mixing and separation  Processes in which the mixing and separation in separate derten devices are executed and intermit tively or cyclically working mixing-separation processes (Ahell, King: New Developments in Liquid-Liquid Extrac tors, AIChE Symp. Ser. 80, 238, 1984).

The procedures belonging to the first group are carried out mixing and separating at the same spatial Place and same time. This group includes for example rotating disk extractors, in which non-mixing phases that are drawn in spontaneous countercurrent led by me Chanian mixing elements are mixed together (Kosters, W.C.G .; Rotating-Disk Contactor, Lo, T.C., Baird, M.H.I. and Hanson, C. eds .: Handbook of Solvent Extraction, Wiley-Interscience, New York, 1983). These Methods are primarily for contacting two Liquids are suitable and are less reliable, though Solid materials are present.

For the work units belonging to the second group is mixing and separating in two separate pre directions carried out, for example mixing in a container that is stirred mechanically and the Se parry in a separation centrifuge or in the case of a solid-liquid system in a filter trifuge. These methods can be used inter be carried out in the middle or continuously. There is also a pneumatic mixing instead of the me Chanish mixing possible. The one for mixing and se parry in separate functional units required Effort especially due to the additional separation unit will be raised.  

The third group includes those who work cyclically Mixing-separation processes, for example the mixer-Ab Scheider processes. With these processes the Wed takes place and phase separation in the same volume or Space of the work units, but one after the other. A disadvantage of the mixing-separating processes is that Presence of a solid phase promoting the Ma terials is difficult.

The object underlying the invention now exists in creating a method and an apparatus with which it is possible when using simple components is to train work units that a multi-hour Enable countercurrent contacting and in the same Way for any desired phase system, for example for two immiscible liquids, such as sentimentation of solid material, for floating solid Use material, at the same time a gas phase may be present in the cases mentioned.

To solve this task, the modern computer and control technologies, whereby work units from simple elements such as pipes, pipe bodies, Broaching with stirrers, pumps, lifting with air and the same can be summarized in a work unit.

The object underlying the invention is achieved by solved a method in which two phases to each other fed in opposite directions at two ends of a cascade be made up of a variety of connected in series Levels. In the mixing-separating room of the individual The phases become stages at least once per cycle mixed, separated spontaneously by gravity, the  separated phases at least partially between neighboring beard stages transferred in countercurrent and at the two Ends of the cascade. The easier phase is from the outside into the top step of the cascade led, the steps arranged in an inclined row are not. After separating the phases starting from the lowest level and progressively progressing to the top The highest level is a predetermined amount of a heavy metal phase in the individual stages of a separate Space section of the given level in the lower section of the mixing-separating room, which makes a suitable amount of lighter phase from the mixing-separating Space pushed out and under the influence of gravity is fed to the mixing-separating room of the lower stage, the easier phase in the lowest stage is led outside. The hardest phase is in the first stage introduced between two adjacent stages of the transported low to the higher and finally out of the removed from the top stage.

Advantageously, the lighter phase from the one individual stages driven out by the pressure of a closed gas space is increased, which over the sw reren phase is arranged in a separate room, wel kitchen with the mixing-separating room in the manner of communication renden containers is connected. Then through Removing the overpressure the balance of each other the communicating container is restored. The Generation and removal of the excess pressure can for example with the help of valves or other shut-off devices be carried out in such a way that the gas space deviates alternately with a manostat (pressure source) with higher pressure  and then connected to one with lower pressure. These agents work with the help of suitable ter timer, but preferably by means of a tax unit that has a programmable microprocessor points.

In another advantageous embodiment of the method this makes the easier phase from the individual stages ousted that preferably a gravitational pull rere phase in the mixing-separating room from the separate Space section is fed. In this case, before partly driving out the easier phase as well the transition of the difficult phase in each one Level performed, starting from the bottom.

According to the method of the invention, the lighter Phase to the mixing-separating room and / or to the separate th room section of the adjacent higher level. In some cases, part of the heavier, from which Mixing-separated room of the individual stages heavier phase to the separate room section of the Stage recycled.

The heavier phase can be fed in any suitable way th conveyor, suitably a pump or with the help of pneumatic devices.

In the process it is useful to have a level sensor in the mixing-separating room and in the separate room cut and the quantities supplied to the regulate this basis.  

When using the process, either the heavier or the lighter phase is a solid material that in the course of the separation out of the liquid and floats to the upper part of the liquid space. The liquid phase can also contain gas bubbles. The individual components of the phases can be used during the pro processes physically and / or chemically ren.

The device according to the invention has been connected in series Steps that are provided with couplings that are suitable for this net are to add and remove the phases and the To transfer phases, the stages with mixing-separating Rooms are provided, which are equipped with stirrers. The individual levels also contain a separate one Room section that has piping to the lower one Section of the mixing-separating room is connected. you are also with devices, suitably valves or pumps to regulate the flow of the heavier phase through provided the piping. The steps are inclined in one th row arranged. The upper part of the mixing-separating Each level of the room is provided with couplings for loading and promoting the lighter Pha se as well as for the transfer of the easier phase from serve top down due to gravity. The un tere mixing-separating room is via a pump or a Air lifter with the mixing-separating room and / or the ge particular section of the neighboring higher tier connected.

In a preferred embodiment of the invention Device is the separate section on the top closed, in the immediate vicinity of the mixing-separating  Space arranged and thus in the manner of communicating Containers connected and with gas inlet and gas outlet devices preferably valves connected.

In another preferred embodiment, the separate room section open and above the mixed sepa rier room arranged, but with a line connected with a shut-off device, for example as a valve is provided.

Finally, the floor of the mixing-separating room can be used the separate room section of the same level as well that of the neighboring higher stage by means of a pump and shut-off devices, preferably valves, verbun be that.

In the device, the shut-off devices, näm Lich expedient valves, with a microprocessor controlled timer connected.

The separate room section with the mixing-separating A pump can be arranged in the line connecting the space. A mixer can also be installed in separate room sections and level sensors are arranged.

Exemplary embodiments of the Invention explained in more detail. It shows:

Fig. 1 in a side view a first embodiment of a stage of the apparatus,

Fig. 2 shows the stage of Fig. 1 in end view,

Fig. 3 shows the stage of Fig. 1 in top view,

Fig. 4 schematically shows a six-stage device,

Fig. 5 is a plan view of the device of FIG. 4,

Fig. 6 shows an embodiment of the compound of air lift,

Fig. 7 is a plan view of a portion of Fig. 6,

Fig. 8 shows a further embodiment of the compound of the air lift,

Fig. 9 is a plan view of a portion of Fig. 8,

Fig. 10 shows schematically the periodic operation of the device and before

Fig. 11 schematically shows another embodiment of the device.

The stage of the device shown in FIGS. 1 to 3 consists of a cylindrical mixing-separating space 2 and a separate space section 3 , which is connected to the bottom of the mixing-separating space 2 in the manner of communicating containers by a line 4 . To transfer the easier phase, connectors 5 are connected with an inclination of about 70 ° to the lower section of the mixing-separating space 2 . For mixing the phases in the mixing-separating space 2 , an air lifter 16 is connected from the outside to the housing of the device, into which an air stream can be introduced via a valve 25 . Level 26 illustrates the nominal delivery level of the device. Above the level 26 of the separate room section 3 is a closed gas chamber, the top of which is connected via valves 12 a and 12 b to monostats of different pressures. To discharge the heavier phase, the line 4 , which is connected to the bottom of the mixing-separating space 2 , is provided with a connecting piece 7 , to which an air lifter 22 is connected.

When the device is in operation, the phases contained in the mixing-separating space 2 up to the level 26 are mixed by the air lifter 18 , which is actuated by the air which is supplied via the valve 25 . After the mixture has ended, the phases separate spontaneously, the lighter phase forming the top layer. Then air is fed via the valve 12 a into the separate space section 3 and the pressure in the closed space is increased. The equilibrium of the communicating container is thereby interrupted, as a result of which the level in the mixing-separating space 2 rises and the lighter phase located on the upper side as a layer is removed by a spontaneous gravity flow through the lower connecting piece 5 . The introduction of the light phase ren over the upper connector 5 is now from the neighboring and built in the same way higher stage. The heavier phase forming the lower layer is removed by the air flow which is introduced into the air lifter 22 through the connecting piece 2 . The heavier phase can either be introduced into the mixing-separating room 2 or into the separate room section 3 .

The device shown in Fig. 4 has six stages I to VI, which are connected in series inclined downwards. The easier phase passes from the charging device 17 into stage I and is guided between the individual stages due to gravity via the connecting piece 5 and finally reaches a vibrating screen 28 . The heavier phase is introduced into stage VI by a pump 29 , transferred between the stages with the aid of the air lifter 22 ( FIG. 2) and discharged from stage I via the connecting piece 7 .

As can be seen from Fig. 5, belonging to each of the stages I to VI respectively two air lift, of which the air lift 18 of the phases in the mixing cycle performs the external circulation / mixing, while the air jack 22, the heavier phase higher to the adjacent Stage leads.

In Figs. 6 to 9, two variants for the connection of the air lift are shown. In the variant according to FIGS. 6 and 7, the heavier phase is led from the bottom of the step with the aid of the air lifter 22 to the mixing / separating space 2 of the adjacent higher step. In the variant according to FIGS. 8 and 9, the heavier phase is recycled from the bottom of the stage to the separate spatial section 3 of the adjacent higher stage III. In both embodiments, the air lifters 18 serve to stir the material into the mixing-separating space 2 of their own stage.

The exemplary cycle cycles of the device's periodic operation can be monitored using the diagram shown in FIG . The individual cycles are:

a) Mix

By opening the valve 25 , all external stirring of the air lifter 18 of each stage is actuated, the phases being mixed over a predetermined period. The heavier phase introduced into the mixing-separating space 2 breaks up during the mixing cycle from top to bottom, while the light phase floats to the top of the solution. The air lifter 18 circulates the suspension by increasing the flow rate.

b) separation

By closing the valves 25 , the mixing is interrupted. There follows a rest period with a specified length. During this time, the phases are separated spontaneously.

c) Step transport or moving the lighter ones forward phase

Starting from the lowest level and progressing in the reverse direction Rich, the valve 12 a of each stage is opened in succession. The liquid level of the separate room section 3 is pressed from the base level L to the previously set level G. This has the effect that the level in the mixing-separating space 2 rises and that the corresponding volume of the lighter phase flows to the lower stage next door. When the level G is reached, the valve 12 a is closed and the valve 12 b is opened. As a result, the excess pressure in the gas space 11 is reduced and the equilibrium of a communicating container is restored. To ensure that the entire prescribed volume is transferred to the lighter phase, the compression can be carried out several times in succession. By starting the stage transport at the lowest stage VI and by progressing upwards, the stage transport takes place in each stage. Finally, in stage I, the lighter phase is supplied from the outside ( FIG. 4). In the stages in which the light phase has already been supplied, the air lifter 18 , which carries out circulation mixing, is actuated immediately.

d) mixing

This takes place during a prescribed period as in a).

e) Separate

This takes place during a prescribed time as with b).

f) Step transport of the difficult phase

First, heavy phase is removed from the top stage I ( FIG. 4) with the aid of the air slide 22 until a given level has been reached. Thereafter, such an amount of heavy phase is transferred from stage II via the associated air lifter 22 to stage I until it is required to restore the base level L. Then the difficult phase is gradually reversed in series. Finally, the lowest stage VI is also filled with the pump 29 . Thereafter, the operation of the device continues with cycle a) as mentioned above.

The device is operated by a microcomputer using a control calculation scheme. The control system also provides an alarm signal, ie it stops if the lower limit level A or the upper limit level F is reached.

The device shown in Fig. 11 is constructed entirely from conventional mechanically mixed elements. Instead of air lifting conveyors, they are conveyed by pumps.

The device consists of four mixing-separating rooms 2 , which are arranged at an inclination of 30 ° and are provided with mechanical tubes 20 , together with four stages I to IV, which are arranged above them and consist of separate sections 14 , which are equipped with stirrers. The separate room sections 14 are connected to the floor sections of the mixing-separating rooms 2 by lines 19 which have valves 13 . The easier phase flows from level to level via connecting pieces 5 . The heavier phase is in the separate room section 14 of stage VI by a pump 29 leads. The heavier phase is performed from the bottom of the mixing-separating rooms 2 via pumps 21 and valves 30 to the separate sections 14 of the adjacent higher stage and from stage I to the ambient atmosphere and into the separate section 14 of their own stage via valves 31 .

The operation of the cascade is controlled on the basis of the liquid level 16 , the section 14 prevails in the separate room. There are the following working cycles:

a) Mix

This is done by the mechanical stirrer 20 for a predetermined period.

b) Separate

By switching off the stirrers of the mixing-separating rooms 2, the system rests for a predetermined period.

c) step transport

From the separate room section 14 of stage IV, a volume of heavy phase is fed via valve 13 and line 15 into the mixing-separating room 2 , the volume corresponding to the amount of light phase that has to be removed (level control). With the help of the pump 29 , a predetermined level-controlled amount of heavy phase is introduced into the separate section 14 .

While the valve 30 directed to stage III is closed, the heavy phase is introduced via the pump 21 and the open valve 31 , which belongs to stage IV, into the separate room section 14 of stage IV and its level 16 is thereby restored. Thereafter, the valve 30 is opened, the valve 31 is closed and the separate room section 14 of stage III is filled up to the desired level.

An amount of heavy phase, which corresponds to the amount of the light phase to be transferred, is led from the special section 14 of stage III into the mixed separation room 2 .

With the help of the pump 21 of stage III (valve 30 closed sen, valve 31 open), a predetermined, level-controlled amount of heavy phase in the separate Raumab section 14 of stage III is introduced. Then, by opening the valve 30 and closing the valve 31, the separate space section 14 of the stage 11 is filled up to the desired level.

The stage transport is from stages II and then I continued as described above.

Finally, heavy phase is discharged from stage I via valve 30 .

The invention is illustrated by the example below explained further.

A four-stage device which, as shown in FIG. 4, is constructed and consists of stages as shown in FIGS. 1 to 3, has mixing-separating rooms 2 with a diameter of 500 mm, separate room sections 3 with a diameter of 300 mm and a total height of 2000 mm. In stage I of the device, 100 l / h of sulfonated cation exchange resin in 65 kg / h of 90 volume percent sulfuric acid solution are introduced. In stage IV, 167 kg / h of 48 to 50 volume percent sulfuric acid solution are introduced. In all stages the resin floats to the top of the solution. At a mass flow of 82 kg / h, 80 volume percent sulfuric acid is removed from stage I, while from stage IV 100 l / h ion exchange resin and 150 kg / h 50 volume percent sulfuric acid solution are removed. The device has the following working cycles:

• a) Mixing: 4 min;
• b) phase separation: 4 min;
• c) resin transport from stage IV to a vibrating screen, from level III to level IV, from level II to Level III, from level I to level II and from Feeder for stage I;  
• d) mixing: 4 min;
• e) phase separation: 4 min;
• f) supplying the solution: from stage I to discharge, from level II to level I from level III to Stage II and stage IV by a pump.

The loading with resin is based on the in the separate room section measured level with the help an air supply in the separate room section. To Feeding the solution and stirring the mixing-separating Air lifters are used in rooms.

Claims (18)

1. A method for the multi-stage, cyclically continuous countercurrent contacting of a liquid phase with a solid phase having different densities and / or with an immiscible liquid phase, in which the two phases are fed in opposite directions to each other at the two ends of a cascade which consists of there are several stages connected in series, the phases are mixed with one another at least once per cycle in mixing-separating rooms of the individual stages and spontaneously separated by a gravity process and the separated phases are at least partially transferred in countercurrent between adjacent stages and at the two ends of the cascades are discharged, characterized in that the lighter phase is fed from the outside into the top step of the cascade, the steps being arranged in an inclined row, starting from the bottom step and step by step to the top step, a predetermined amount the heavier P hase after the separation of the phases in the lower section of the mixing-separating room from a separate Raumab section of the stage is introduced, whereby the lighter phase is driven out of the mixing-separating room, the lighter phase then under the influence of gravity leads into the mixing-separating room of the neighboring lower stage and is discharged from the lowest stage, while the heavier phase is introduced into the lowest stage and raised between neighboring stages from a lower to a higher stage and from the top stage is dissipated. 2. The method according to claim 1, characterized records that the easier phase from the stages by increasing the pressure in one closed gas space over the heavier phase in egg nem separate space section that is displaced with the mixing-separation room in the manner of communicating Be container is connected and that subsequently by Removing the overpressure the balance of the commu container is restored. 3. The method according to claim 2, characterized records that the expulsion and the over Leading the easier phase in series and sequentially takes place in all stages and that then starting from the top stage is the transfer of the heavier phase is also carried out in series and sequentially. 4. The method according to claim 1, characterized records that the easier phase from the individual stages by introducing the heavier phase expediently under the influence of gravity from the separate room section into the mixed sepa rier room is driven out. 5. The method according to claim 4, characterized records that starting from the bottom Stage exorcising the easier phase and over the heavier phase is carried out in each stage leads. 6. The method according to any one of claims 1 to 5, characterized characterized that the heavier phase in the mixing-separating room and / or the separate one  Space section fed to the adjacent higher level becomes. 7. The method according to any one of claims 1 to 6, characterized characterized that part of that of transferred to the mixing-separating room of the individual stages th heavier phase to the separate room section is recycled. 8. The method according to any one of claims 1 to 7, characterized characterized that the heavier Pha by pumps or by pneumatic devices is transferred. 9. The method according to any one of claims 1 to 8, characterized characterized that the level measurement in the mixing-separating room and / or the separate one Space section is carried out and that the supplied Quantities can be controlled on this basis. 10. Apparatus for multi-stage, cyclically continuous countercurrent contacting of a liquid phase with a solid phase having a different density, and / or an immiscible liquid phase, in particular for carrying out the method according to one of claims 1 to 9, with series connected Steps, which are provided with connectors for feeding and discharging the phases and for their transfer, the steps each containing a mixing and separating space provided with a stirrer, characterized in that the individual steps (I to VI) include a separate room section ( 3 , 14 ), which is connected via a line ( 4 , 15 ) to a bottom section of the mixing-separating room ( 2 ) and is provided with accessories, advantageously valves ( 12 a , 12 b , 13 ) or Pumps, for controlling the current of the heavy phase through the line ( 4 , 15 ) that the stages (I to VI) are all arranged in an inclined row and the upper part of the mixing-separating space ( 2 ) of each stage (I to VI) is provided with connecting pieces ( 5 ) which serve to feed and discharge the easier phase or the transfer of the easier phase from top to bottom under the influence of To ensure gravity, and that finally the bottom of the mixing-separating space ( 2 ) via a pump ( 21 ) or an air lifter ( 22 ) with the mixing-separating space ( 2 ) and / or the separate space section ( 3 , 14th ) is connected to the neighboring higher level. 11. The device according to claim 10, characterized in that the closed at its top separate room section ( 3 ) is arranged closest to the mixing-separating room ( 2 ) and is thus connected in the manner of communicating container and a gas inlet and outlet device, expediently has valves ( 12 a , 12 b ). 12. The apparatus according to claim 10, characterized in that the separate space section ( 14 ) open, on the mixing-separating space ( 2 ) angeord net and thus connected via a line ( 15 ) with a shut-off device, advantageously one Valve ( 13 ) is provided. 13. The apparatus according to claim 12, characterized in that the bottom of the mixing-separating space ( 2 ) via a pump ( 21 ) and shut-off elements, namely valves ( 30 , 31 ), with the separate Raumab section ( 14 ) of the same Level and the adjacent higher level is connected. 14. Device according to one of claims 10 to 13, characterized in that the blocking elements, namely the valves ( 12 a , 12 b , 13 , 30 , 31 ) are connected to a timer controlled by a microprocessor. 15. The apparatus according to claim 10, characterized in that a pump is arranged in the tube ( 15 ) which connects the separate space section ( 14 ) with the mixing-separating space ( 2 ). 16. The apparatus according to claim 10, characterized in that a stirrer is provided in a separate Raumab section ( 14 ). 17. Device according to one of claims 10 to 16, characterized in that level sensors are arranged in the separate room sections ( 3 , 14 ). 18. Device according to one of claims 10 to 17, characterized in that the shut-off elements, namely valves ( 12 a , 12 b , 13 , 30 , 31 ), the air lifters ( 18 , 22 ), the stirrer ( 20 ), the pumps ( 21 , 29 ) and the level sensors are all connected to a microcomputer.