KR830000369B1 - Liquid-Liquid Extraction Method - Google Patents

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Description

Liquid-Liquid Extraction Method

1 is a schematic illustration of an apparatus for implementing the general concept of the invention.

2 is a longitudinal cross-sectional view of the container

3 is a cross-sectional view taken on the line III-III of FIG.

4 is a top plan view showing four container arrangements.

5 is a schematic diagram of a complete peracid generator

The present invention relates to a method and an apparatus for contacting two kinds of incompatible liquid phases, for example, when extracting an organic phase of an aqueous phase.

The present invention describes, in particular, the preparation and extraction of peracids (term means peroxycarboxylic acid), but is not limited thereto. The use of such peracids is well known in the epoxidation of alkenes, in particular lower alkenes.

One skilled in the art of liquid-liquid extraction can readily appreciate that the present invention can be applied to any other method.

A general technique is known for extracting a substance from a first liquid phase by means of a second liquid phase which is incompatible therewith. Usually such extraction is carried out using a countercurrent method. Two of the main devices used are known as extraction towers and mixed settlers. One advantage of extraction towers is that different holding times can be used for the two phases, and one of the drawbacks is the incomplete contact of the two types due to the uneven flow of the two types, especially in large towers.

One of the advantages of a mixed settler is to ensure efficient contact. However, in the normal operation of the mixed settler in the steady state, the holding time of the two types is usually the same regardless of the relative flow rates of the two types because they must be installed in a special recycling step.

The other method, called alternating current extraction, is described in the typesetting of Alder's "Liquid-Liquid Extraction", published in 1959 by Elsevier Press. However, for the reasons described on page 66 of this book, exchange extraction has serious drawbacks, which are “chemical simple” produced by Robert H. Perry published by McGraw-Hill Books Company under the more appropriate name of “simple multilevel contact”. Engineering Handbook ”, 5th edition, pages 15-15.

It is an object of the present invention to provide a liquid-liquid extraction method and apparatus.

According to the present invention, the first liquid phase is continuously passed through a series of extraction steps, and in the series of extraction steps, the first liquid phase is continuously flowed countercurrently with the second liquid phase, and in each extraction step, the second liquid phase is introduced into the first liquid phase. In the liquid-liquid extraction method in which the second liquid phase is dispersed as a coalescing body, the second liquid phase is separated from the coalescing body, and the second liquid phase is taken out of the coalescing body and passed through under the control of the next adjacent step as described above. A liquid-liquid extraction method is characterized in that two stages of flow are traversed to one another to flow the other liquid phase.

According to another aspect of the present invention, a device for introducing a liquid phase into a series of a plurality of containers, the first container of the series of containers, and circulating into the series of containers, the first liquid phase in the last container of the series of containers An ejection apparatus for ejecting, an introduction apparatus for introducing the second liquid phase into the final container, an ejection apparatus for extracting the second liquid phase from the first ware in a series of containers, and a whole of the first liquid phase in each container A second liquid phase dispersing device described in each container suitable for dispersing the second liquid phase, a collecting device for collecting the second coalesced liquid phase in each container for coalescing the second liquid phase, and a series of collected second liquid phases. A liquid-liquid extraction device equipped with a device for moving and introducing into the next adjacent vessel in the air, wherein the two-phase flow in each stage is generally intended to flow across different liquid phases. It provides a liquid-liquid extraction device characterized by having a device.

In a suitable arrangement where all the vessels are in a common horizontal plane, the first liquid phase flows generally horizontally through each vessel and the series of vessels, and the second liquid phase flows generally vertically into each vessel from the dispersing device and one container in each vessel. Will have a dispersing device.

This arrangement is clearly distinguished from the above-described "extraction extraction method" because the two phases flowing through the entire apparatus flow countercurrently. A pumping device is usually required to transport the second liquid phase from one vessel to another, which conveniently serves to regulate the transport of the second liquid phase from one stage to another.

According to a typical embodiment in a conventional column, the second liquid phase (which forms a dispersed phase) is the phase on which the device is distributed in a large amount according to the unit time. The difference in specific gravity of these two companies determines whether the dispersed phase rises or falls in each container. Dispersion of the second liquid phase is effected effectively by a suitable dispersing device such as a spray-head, a reticulated plate, but in a stirrer, the second liquid phase is coalesced (which is usually separated in a mixed settler). It is not done in a container or compartment, but in a same container).

However, each vessel may be provided with a stirring device, for example, a stirrer or a gas suction pipe, for use only under operating conditions.

In the aqueous medium, a general method for producing peracid by reaction of carboxylic acid with hydrogen peroxide is known, and it is also well known to extract such peracid into an organic solvent. One method for the production of peracids is described in DOS 2602776 (GC36), and another method is described in BP 1, 425, 077.

As mentioned above, the known use of peracids is epoxidation, and the present invention is particularly suitable for incorporating such operations. Therefore, a feature of the present invention can be used to extract peracid from an aqueous solution into an organic solution. In addition, the aqueous solution of peracid is generated by feeding the aqueous solution of hydrogen peroxide countercurrently to the organic solution of carboxylic acid.

Compared with the conventional method as follows.

The most suitable form of the conventional method is a combination of a conventional mesh tower and a conventional mixed settler. In general, the present invention can be considered as a hybrid of these two conventional extraction apparatuses. Therefore, the device of the present invention can be controlled in the same way as the reticulated tower, and does not have the disadvantage known to exist in the reticulated tower. On the other hand, since the physical arrangement of the extraction step is the same as the mixed settler combination, the known advantage of the mixed settler arrangement is to have them, but there is no disadvantage in the limitations on the residence time in the mixed settler combination.

Assuming that the peracid, perpropionic acid, which is a more suitable compound for the reasons described below, and that the organic solvent is propylene dichloride, in the technical aspect, the specific gravity of the aqueous phase is affected by the concentration of sulfuric acid in comparison with the conventional method. This sulfuric acid concentration affects the reaction rate. Since the optimum concentration of sulfuric acid in relation to the degree of reaction and the reaction rate shows an imaginatively large specific gravity with respect to the specific gravity of the organic phase to the aqueous phase, the thickness of the organic phase under the reticulated plate of a conventional reticulated plate is a stable emulsion of the pore size of the reticulated plate. There is some risk that the destruction of the unincorporated phase will occur unless it is reduced to the value that allows the liquid to be produced. Problems related to this are particularly pronounced in large diameter towers, as the risk of local poor dispersion of the phase is increased, as is known, especially in large diameter towers (cross sections larger than 10 m 2) used in mass production. In addition, in the case of such a large tower, it is difficult to prevent the flow of the aqueous phase, and therefore, it is difficult to operate the large conventional tower with the efficiency required for the selected reactive agent.

In theory, even if uncontrolled decomposition of the peroxide reactant and product does not occur, it is functional, and if this happens, serious damage to the device occurs. There is a possibility of such disassembly, so it is necessary to use a means to control them, which is difficult and expensive in large towers. It is known that it is difficult to remove heat generated in a tower and to exhaust the contents of several towers quickly. Decomposition also inevitably involves gas generation, and since this gas is controlled by a high hydrostatic pressure, another problem arises.

A suitable apparatus of the present invention is a unit of an organic phase which disperses the organic phase in a series of vessels at a rational efficiency more practically, raises small droplets of the organic phase through the aqueous phase, coalesces and stabilizes the aqueous phase on the aqueous phase. Are arranged to form. This coalescing is adjusted to any convenient depth that cannot be determined by the flow resistance provided by the reticular plate of the stage just above, as occurs in conventional towers. Thus, only the monolithic phase can pass through the mesh at each stage. This transport is usually done by pump and under control to maintain the integral phase in each vessel at a suitable depth. Therefore, it is possible to minimize the above-described problems of hydrodynamic instability seen in conventional large towers. The effect of minimizing this hydrodynamic instability inevitably minimizes the risk of chemical instability that arises mainly because the phase does not have time to react at each stage or to reach equilibrium at each stage. Nevertheless, if hydrodynamic instability occurs in the apparatus of the present invention, the effect is usually limited in a single vessel since the generated gas cannot pass from one vessel to another. Therefore, it is necessary to isolate the container in which the side effect occurs, and if necessary, the cold substance of the container in which the side effect occurs can be evacuated by a known method. This is simpler, faster, and easier to work than exhausting the entire contents of a conventional tower.

In addition, unlike the conventional mixing settler, the residence time of the two phases can be controlled separately, which has the advantage that the reaction can occur simultaneously with the extraction.

Therefore, the device of the present invention can be designed more efficiently and more safely since it is easier to control than the conventional large diameter tower. Such a device of the present invention is quite similar to a mixed settler combination, but can achieve the desired technical performance without the known disadvantages of the mixed settler.

The method of the present invention is schematically described as follows.

The present invention is particularly advantageous in large scale extraction operations, in dangerous methods where chemical instability occurs, in chemical reactions occurring simultaneously with extraction operations, or in methods where hydrodynamic instability occurs due to large specific gravity differences. This method is conveniently described by the operation of producing peracid by reacting with hydrogen peroxide and carboxylic acid, and extracting it in an organic solvent. Therefore, the present invention is described in particular with reference to this method. Peroxide organic solutions are useful for, for example, epoxidizing alkenes to make oxytans and epoxides, contributing to describing such end-use methods. The method to be described uses an aqueous phase, but in the present invention, two kinds of incompatible organic liquids may also be used.

The selection of the carboxylic acid is as follows.

As used herein, the term "carboxylic acid" has a general meaning, and in the practice of the present invention, appropriate selection of "carboxylic acid" and "organic solvent" is necessary to obtain optimum efficiency. However, this choice can be made by the skilled person. In selecting sufficient water-soluble carboxylic acids for the reaction to occur, it is necessary to select the carboxylic acids so that extraction can be carried out so that the carboxyl and its peracid are soluble enough in an organic solvent. For this reason, it is preferable to use mono-carboxylic acids having no substituents of at least 2 or more and 6 or less carbon atoms.

Suitable carboxylic acids are acetic acid and propionic acid.

The selection of the solvent will be described as follows.

The method of extracting the organic acid at the same time as the reaction to produce the peracid is described in detail, but a method of performing the same criteria as the separation of the reaction and extraction may also be applied.

The main function of the organic solvent is to provide a discontinuous organic phase in which carboxylic acids and peracids can be dissolved. Other desired selection criteria for organic solvents are non-reactive at low solvent power in water, low solubility in aqueous sulfuric acid solution and reaction conditions in the presence of other reactants. Although various solvents are listed here, the solvent selection in actual use depends on the end use of the operation, the antisolvent and the peracid.

Solvents are halogenated, for example fluorinated or chlorinated aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, for example,

Dichloromethane, trichloromethane, tetrachloromethane, chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1, 1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, 1-chloropropane, 2-chloropropane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3- Dichloropropane, 2,2-dichloropropane, 1,1,1-trichloropropane, 1,1,2-trichloropropane, 1,1,3-trichloropropane, 1,2,2-trichloropropane, 1,2,3-trichloropropane, tetrachloropropane, chlorine-substituted butanes, pentane or hexane, cyclohexyl chloride or chlorobenzene.

Chlorinated hydrocarbons are usually considered quite inert, and these chlorinated hydrocarbons generate chlorides, which are highly corrosive in the presence of water and sulfuric acid. Thus, non-chlorinated hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons and alkyl-aryl hydrocarbons are preferably selected from, for example, decane, heptane, cycloheptane, benzene, toluene or xylene.

Other solvents generally known in the field of peracids can also be used.

The solvent mixture may use, for example, what is known as petroleum ether which is a mixture of aliphatic hydrocarbons or a mixture of solvents described individually above.

Unsaturated bonds do not epoxidize under the conditions of the present invention and the organic solvent does not have to be a saturated compound.

Of all the solvents listed, most suitable are 1,2-dichloroethane (ethylene dichloride) 1,2-dichloropropane (propylene dichloride) and benzene.

The production of peracid is described as follows.

Before describing the device of the present invention, it is appropriate to describe the reaction itself in a general manner. In the reaction, an aqueous phase composed of sulfuric acid, hydrogen peroxide and water, and an organic phase composed of carboxylic acid and organic solvent are passed through a countercurrent extractor.

The component is partitioned between the two phases, and in the aqueous phase, the reaction of hydrogen peroxide and carboxylic acid to produce peracid is contacted by sulfuric acid. This reaction usually slowly equilibrates, but is facilitated by extracting peracids into the organic phase.

In addition to its catalytic function, sulfuric acid has a function of controlling the specific gravity of the aqueous phase to form a phase separation. The relative specific gravity of the organic and aqueous phases determines the direction of movement upon separation after it is mixed. However, as is known, sulfuric acid concentration should be sufficient to show sulfuric acid catalysis, but care should be taken to maintain an insufficient concentration to cause decomposition of organic components by dehydration. The optimization of sulfuric acid concentration in the chemical standard and extraction operation standard tends to induce liquid relative density, mesh size, residence time, etc. which are difficult to handle in the conventional apparatus. However, the optimum concentration is rarely a problem in the apparatus of the present invention. Do not.

The aqueous liquor taken out of the extractor is virtually replaced by some or all of the hydrogen peroxide therein. It is therefore preferred to remove the water, concentrate, and then recycle hydrogen to the operation of the process of the invention after the addition of hydrogen peroxide.

The general conditions for producing peracid are as follows.

The peracid preparation portion of the present invention is described in more detail under the specific preparation of perpropionic acid using propylene dichloride as an organic solvent, and the aqueous phase is fed to an extraction device and passed through this device. Such aqueous phases include sulfuric acid, hydrogen peroxide and water. The proportion of sulfuric acid is between 30% and 60% by weight, preferably at a concentration of 40% by weight. For operational reasons it is convenient to derive sulfuric acid from 75% by weight of sulfuric acid in water, which together with supplemental acid forms a feedback back from the purification step described below. Hydrogen peroxide is 10% -35% by weight of the aqueous phase and in fact 29% by weight is most preferred. Such hydrogen peroxide is conveniently supplied as a 70% by weight solution in water. Water constitutes the third component of the aqueous phase and its proportions are readily apparent depending on the difference.

The organic phase is fed to the extraction apparatus and flows countercurrently to the aqueous phase, which when prepared perpropionic acid is a solution of propionic acid in propylene dichloride. The concentration of propionic acid is suitably 15% -30% organic phase, particularly 20%.

The relative volume of the aqueous phase and the organic phase passing through the device in unit time and their concentrations together determine the ratio of hydrogen peroxide to propionic acid, the ratio being 1: 0.5-1: 4 as molar ratio, preferably 1: 1.4, The stoichiometric ratio is 1: 1.

In order to extract all propionic and perpropionic acid from the aqueous effluent in the extractor, it is better to extract the aqueous phase from the extractor once more using a new organic solvent.

It is also convenient to back-flow the organic phase to remove dissolved hydrogen peroxide, which separates the aqueous phase injected into the extractor with dilute sulfuric acid and the other part with hydrogen peroxide. To be introduced.

Similarly, the hydrogen peroxide injection can be divided into two or more parts and introduced at remote locations in the device.

Since the reaction proceeds at a satisfactory rate naturally, the operation at natural temperature is satisfactory. The delay temperature is somewhat preserved in the scale effect because some heat is generated during the mixing of the reactants and their reaction. Since the reaction is hardly temperature sensitive, no special measures are required, and a temperature of 0-30% is preferred.

Table 1 shows some relevant data as a guideline for selecting the reactant solvent for peracid preparation.

TABLE 1

Notes on Table 1

1. Values for aqueous solutions at 25 ° C

2. The symbol for solubility is taken from the Chemical and Physics Handbook, 46th Edition, published by Chemical Rubber Company.

In order to more easily understand the present invention, embodiments will be described as follows with reference to the accompanying drawings. Referring first to FIG. 1, the apparatus introduces an organic phase disposed in a position to collect the organic phase on the reticulum 11 installed near the bottom of the container and on the lower portion 13 of the reticulum 11 as in a conventional manner. Each container has a series of containers with spheres 12.

The organic phase passes through the reticulum 11 and is collected into the organic layer 14 at the top of the vessel. The organic phase is withdrawn from the upper organic layer 14 via the outlet 15 and sent to the next adjacent vessel by the pump 16. Similarly, each vessel is provided with an aqueous phase inlet 17 and an aqueous phase outlet 18 arranged to flow countercurrently with the organic layer through a series of vessels, the aqueous phase outlet 18 of one vessel being the next vessel. It is connected to the aqueous phase inlet 17 of, and the movement of the two liquids in each container flows transverse to each other.

2 shows the arrangement of one container in more detail.

The container comprises a conventional tank 10 having a side wall 20 and a bottom 21, the tank having a lid 36 for preventing accidental dropping of the material and a vent to prevent pressure in the tank. And cover 37 which opens and closes freely. There is a free space 22 between the lid 36 and the upper surface of the liquid in the tank. The upper liquid level of the liquid in the tank 10 is defined by a weir 23, which is arranged to protect the organic phase outlet, and firstly to accurately maintain the liquid level of the liquid in the tank 10. Only the organic phase flows out into the outlet 15.

A baffle 24 is used to prevent the aqueous phase from flowing from the aqueous phase inlet 17 to the aqueous phase outlet 18 without proper mixing with the organic bath in the tank. It is convenient to arrange adjacently. However, if the geometry in the tank can be arranged, sufficient mixing can be facilitated by the tank design and no separate baffles are needed. The vessel described in FIG. 2 acts without limitation on adjacent stages in the same manner as one stage of a multistage column. For example, in the structure of the present invention, the depth of the organic layer 13 under the network plate 11 should not be equal to the depth of the upper organic layer 14 at the top of the tank. This change is not possible with conventional columns.

In FIG. 1 the aqueous phase is shown flowing from one vessel to another without pump transport between vessels. However, the organic phase needs to be pumped to overflow at the top of one vessel and then introduced to the bottom of the vessel. Here, a conventional mechanically or electrically driven pump may be used, but other types of pumps may be used because the power requirements are very small. A suitable type of pump, known as a gas report pump, is described in FIG. The organic phase enters the pump through side limbs 25 coupled to the organic phase outlet 15 of the previous stage and enters the open rim of the U-pipe 26.

The second rim of the U-tube 26 has a gas injector 27, which forcibly transports the gas-liquid mixture to the separation chamber 28. The gas is separated in separation chamber 28 and discharged to line 29 for recirculation, while the organic liquid flows down the tube 30 by gravity and flows into organic phase inlet 12. Suitable gas for gas lift is nitrogen. The operating efficiency of the gas lift as a pump depends on the liquid level on the U-pipe 26, which depends on the velocity flowing over the weir 23 of the previous stage. Thus, the system has its own regulating power.

When the device is shut down for some reason, a continuous reaction occurs in the individual containers, but under stationary conditions it tends to overheat due to the absence of fluid flow through each container. If designed to remove this heat or reduce the progress of the reaction, each vessel should be equipped with a spiral cooling coil or stirrer. Under normal operation of the vessel, the stirrer is not operated and the coil is ineffective. However, in the stationary state, coolant is supplied to the coil, and the stirrer is operated so that each vessel is effectively cooled and becomes a stirred vessel.

3 shows that a cooling tube 31 is disposed adjacent to one wall of the vessel, and the one wall has a vertical cooling flow path for the aqueous phase and the organic phase, respectively, along with the vertical baffles 32 and 32a provided close thereto. Separate columns forming the vertical dike, which are shown in Figs. 33 and 33a, are indicated. The ends of these cooling passages 33 and 33a are located below the upper surface of each of the aqueous and organic liquid phases as shown. If additional flow is required through the cooling conduits instead of the downward heat siphon effect, the lower part of the cooling conduits 33 may be filled with nitrogen, for example gas or other gases used in the gas lift pump. It can lead to the dispersion section 34.

It can be seen that the gas lift pump does not operate under the stop condition of the apparatus, and this can be done by operating the exhaust valve 39 if it is necessary to exhaust the contents of any selected vessel.

Another structure of the FIG. 1 device that does not require the baffle 24 shown in FIG. 2 is shown in FIG. In Figure 4, the delusions are omitted for clarity of explanation. In this arrangement the containers are arranged in contact with each other and the containers are longer and thinner than in FIG. The organic phase moves the tube 30 as indicated (pump not shown) and this structure is such that the aqueous phase is corrugated through a series of vessels, the aqueous phase inlet 17 the aqueous phase and the outlet 18 ) Was replaced by a hole 35. As regards the aqueous solution here, this arrangement can be regarded as an extrusion flow reactor. Referring to FIG. 4, it can be seen that the flow of the aqueous phase is easily controlled by a simple method of controlling the flow from the final stage by the interface control device on the first stage. As mentioned above, the arrangement of the weir and the gas lift pump controls the organic phase. As in the tower, the residence times of these two phases need not be the same. In this respect the device of the present invention differs significantly from the mixed settler arrangement.

A suitable arrangement for the complete range is illustrated in FIG. The device indicated for the embodiment is described as 27 separate vessels arranged in three sets of in series and one or two sets of these in series can be replaced with one or more conventional towers as generally described by the DCS described above. have. The apparatus described in FIG. 5 is for use with an epoxidation apparatus, which supplies the peracid solution in an organic solvent to the epoxidation apparatus, and from the epoxidation apparatus, the apparatus is used for carboxylic acid and organic in an organic solvent. Receive separate recycles of solvent. In particular, the apparatus described in FIG. 5 is for the production of perpropionic acid using propionic acid as the carboxylic acid and propylene dichloride as the organic solvent.

Three sets of vessels were arranged to act in series, ie countercurrent. The main reaction takes place in a series of vessels in the center called the “reaction stage” (102). The organic phase is supplied from reaction step 103 and the aqueous phase is supplied from organic phase backflow step 101.

Hydrogen peroxide is supplied from the hydrogen peroxide storage tank 105 to the right side of the reaction step 102 by the wiring 104, and aqueous sulfuric acid solution is also supplied to the right end of the reaction step 102 by the wiring 106, which is actually As described in detail below, it is a recycled phase.

The aqueous sulfuric acid solution is also supplied from the left end of the acid backflow step 103 to the right end of the reaction step 102 by the wiring 107. Hydrogen peroxide, sulfuric acid, and water supplied by the wirings 104, 106, and 107 together form an aqueous phase. The organic solution of propionic acid in propylene dichloride is supplied from the right end of the organic phase backflow step 101 to the left end of the reaction step 10 2 by the wiring 108. The new propionic acidity wiring in propylene dichloride from replenishment storage tank 110 is supplied to the left end of reaction step 102. Finally, the recycle flow phase containing propionic acid in propylene dichloride is supplied to the left end of the reaction step 102 by the wiring 111. Propionic acid and the organic solvent provided at the left end of the reaction step 102 by the wirings 108, 109, and 111 together form an organic phase. The organic and aqueous phases react countercurrently through reaction step 102 to produce perpropionic acid, which product is extracted into the organic phase.

Thus, the aqueous solution containing sulfuric acid and water is taken out from the left end of the reaction step 102 by the wiring 112, and is supplied to the right end of the organic phase backflow step 101. The solvent which does not actually contain propionic acid is supplied to the left end of the organic phase backflow step 101 by the wiring 113, and passes the aqueous sand countercurrently to remove as much propionic acid as possible. The condition is that the aqueous effluent taken out from the left end of the organic phase backflow step 101 should not actually contain propionic acid, perpropionic acid or hydrogen peroxide.

The organic solution from the right end of step 102 becomes a solution of perpropionic acid in propylene dichloride, which is withdrawn from reaction step 102 by wiring 115 and acts as an aqueous phase countercurrent step 103. Supplied to wealth. Fresh sulfuric acid in the aqueous solution is supplied to the right end of the step 103 from the supplemental storage tank 117 by the pipe 116, and this sulfuric acid is taken out from the step 103 by the wiring 107. The function of this aqueous acid backflow is to strip off the organic phase flowing through step 103 and remove as much of the peroxide as possible from it.

The organic solution of perpropionic acid is taken out as a product from the right end of the acid reflux step 103 by the wiring 118.

The aqueous solution taken out from the left end of the organic phase reflux step 101 by the wiring 114 may be used as a recycle flow, but at least part of the aqueous solution reacts with hydrogen peroxide to react with water. This contains too much. Therefore, the wiring 114 is connected to the distillation column 151, where the aqueous solution is distilled to produce light oil made of substantially water, which is taken out and discarded by the wiring 152 of water.

The heavy oil from the distillation column 151 becomes an aqueous sulfuric acid solution in water, and it is convenient to re-distill to remove the high boiling impurities, where the high boiling impurities are accumulated in the aqueous phase.

However, in a suitable arrangement, a part of the heavy oil from the distillation column 151 is taken by the wiring 153, and the remaining aqueous phase effluent is returned to the right end of the reaction step 102 by the wiring 106.

Steps 101, 102 and 103 are not operated at room temperature, i.e., heated or cooled, and are preferably operated under normal hydrostatic pressure. Distillation column 151 operating in the recirculation system is convenient to operate at a temperature of 130 ℃ and pressure of 100 torr.

In a practical embodiment of the present invention, the apparatus is substantially identical to the arrangement shown in FIG. 4, except that six containers are installed. Each container is 5 meters long, 2.5 meters wide, and the whole is arranged within a 15 meter angle. The height of each vessel is 3.3 meters and the top surface of the liquid is 2.6 meters from the bottom of the vessel to provide 700 mm of free space under the lid. The device is made of 316 grade stainless steel, and the reticular plate 11 is 200 mm away from the container bottom 21, and is attached on the horizontal angle so that they are horizontal. Each reticular plate has about 12, 000 holes having a diameter of 3 mm, and is arranged on a 30 mm square pit. Under normal operating conditions, the interface between the aqueous phase and the organic phase is 2.4 m from the bottom of the device to represent an organic phase integrated layer about 200 mm deep.

The residence time designed for the aqueous phase to emphasize the difference between the device and the mixed settler by this footing is 80 minutes per stage, with a total residence time of 480 minutes, while the designed residence time for the organic phase is 1 The total stay time was 18 minutes in 3 steps. Because of the relatively large stationary agglomerated phase, the organic phase spends most of its residence time in addition to contact with the aqueous phase, with a total contact time of about 10 minutes. However, the aqueous phase is in contact with the organic phase for substantially the same time as its residence time.

The steady state flow to the first vessel of step 102 by scaling up from a smaller plant is expressed as tons per hour as follows.

The total aqueous phase inlet liquid volume is about 19 m 3 / hour.

The amount of outflow of the aqueous phase in the wiring 112 is 18.6 m 3 / hour and is expressed as tons per hour as follows.

The amount of organic phase entering the initial vessel of step 102 in the tube 30 is expressed as tons per hour as follows.

The flow rate of the layer organic phase is about 110 m 3 / hour, and the flow rate of the organic phase on the wiring 115 is 112 m 3 / hour, and it is expressed as tons per hour as follows.

If the same reaction is carried out in a conventional network column, 20 or more network panels of 600 mm intervals are required, i.e., the tower height is about 12 m and the diameter is 4 m. Such towers are difficult to control and expensive to manufacture.

Claims (1)

The first liquid phase is continuously passed through a series of extraction steps, and in the series of extraction steps, the second liquid phase is continuously passed countercurrently with the first liquid phase, and in each step of the extraction step, in the first liquid phase, The liquid-liquid extraction method by dispersing, coalescing the second liquid phase to separate the second liquid phase into a single body, taking the second liquid phase out of the main body, and passing it under the control of the next adjacent extraction step as described above. The liquid-liquid extraction method of claim 2, wherein the flow of the two liquid sands flows across different liquid phases.

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