JP2009028589A - Gas lift type crystallization apparatus and crystallization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize an agitation mechanism in a crystallization operation to the absolute minimum or dispense with the agitation mechanism. <P>SOLUTION: A solution in which the gas from an absorption condenser 10 is absorbed and mixed is supplied to the inside of a draft tube 31 of a crystallization tank 30 so that the dissolved gas is vaporized and raised and a convection current is produced in the crystallization tank 30 to obtain an agitating effect of the crystal slurry in the crystallization tank 30. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a crystallization apparatus and a crystallization method in which gas is generated or entrained. In particular, the present invention relates to a crystallization apparatus and a crystallization method suitable for obtaining a paraxylene or cyclohexane crystal by adiabatic cooling by vaporization of dissolved gas.

The present applicant has proposed the invention described in the following patent document regarding an organic compound crystallization apparatus and method using adiabatic cooling. These inventions propose separation and purification by crystallization as a method for efficiently separating the target component from a mixture such as an isomer mixture having close boiling points as represented by the para-xylene-mixed xylene system. To do.
This method proposes adiabatic cooling crystallization by evaporating a refrigerant gas component dissolved in a mixture liquid in order to reduce equipment costs and operating costs. According to the invention described in the above-mentioned patent document, it is possible to reduce the size as compared with the indirect cooling method, which had to be a large facility in the prior art, and further reduce the operation cost.
However, when a flammable substance such as propane is used as the refrigerant gas, a large-scale sealing mechanism is required in the driving portion of the agitator of the crystallization tank so that the refrigerant gas is not exposed to the atmosphere. In addition, in the case of a large facility, a large stirring mechanism is required to sufficiently circulate the crystal slurry generated inside the crystallization tank, making it difficult to design the crystallization tank together with the sealing mechanism described above. Furthermore, the production cost of the crystallization tank is increased.
JP 2006-272300 A JP 2006-272301 A JP 2006-272302 A JP 2006-273825 A

  Accordingly, a main object of the present invention is to provide a gas lift crystal device and a crystallization method capable of miniaturizing or eliminating the above-described stirring mechanism to the minimum necessary.

The invention that has solved the above problems is as follows.
<Invention of Claim 1>
The solution of the object to be crystallized is introduced into the crystallization tank, and a local distribution of gas is generated in the liquid in the crystallization tank, and due to the local distribution of the gas (by the convection of the solution in the tank, the solution And a gas lift crystallization method characterized by providing a stirrer effect of the staying solution and crystals in the crystallization tank.

(Function and effect)
In order to suppress the generation of microcrystals in the crystallization operation and obtain crystals having a good particle size for the subsequent separation and drying operation and purification operation, the operation supersaturation in the crystallization tank is reduced, and the locality is reduced. Must be suppressed. For that purpose, it is necessary to uniformly mix the crystal slurry in the crystallization tank. Generally, the convection is generated in the tank by a large stirring blade, or a large circulation pump is provided outside and the slurry inside and outside the crystallization tank. A method of obtaining a stirring action by circulating the gas is used.
However, especially when designing and manufacturing a large crystallization tank, installing a large stirring blade not only increases the manufacturing cost of the stirrer, but also the drive part and the seal part of the can and the stirring shaft. The difficulty of design becomes high, and the manufacturing cost of the entire apparatus also becomes expensive. On the other hand, even when an external circulation pump is installed, the pump becomes large in order to obtain a necessary circulation amount in the crystallization tank. Furthermore, there is a case where crystals with good particle size cannot be obtained due to crystal crushing due to collision between the stirring impeller or pump and the crystal.
According to the method of the present invention, a local bubble distribution is imparted to the inside of the liquid or slurry staying in the can, that is, the gas hold-up distribution in the gas-liquid system or gas-liquid-solid system is unbalanced. By generating the balance, a specific gravity distribution (specific gravity difference) generated in the solution in the tank due to the difference in gas hold-up can be generated, and the liquid in the crystallization tank can be stirred using this as a driving force. In other words, in the crystallization tank, the portion where the gas volume is large has a smaller apparent specific gravity than the portion where the gas volume is small. Accordingly, the liquid is moved from a small gas volume to a large gas volume (from a large specific gravity to a small one) in the tank, and the liquid or slurry in the crystallization tank is stirred.
As a result, according to the present invention, even in a large crystallization tank, facilities such as a stirrer and a drive mechanism and a seal mechanism associated therewith can be minimized or omitted. In addition, since a pump for external circulation is not required, the equipment cost can be greatly reduced.
As a method for generating gas in the crystallization tank in the present invention, first, a soluble gas is dissolved in a supply liquid under pressure in the preceding stage of the crystallization tank, and then the pressure is reduced in the crystallization tank. A method for generating gas by secondly, a method for generating gas by boiling the solution before or after supply to the crystallization tank, third, addition of a third component, etc. A method of generating gas by lowering the solubility of dissolved gas by the fourth, a method of generating a gas by a chemical reaction, a fifth, a method of introducing a gas from the outside using a device such as a gas blower, etc. Can be used.

<Invention of Claim 2>
The solution of the object to be crystallized is introduced into the crystallization tank, and convection of the solution is caused by gas rise in the crystallization tank, and the solution and the staying solution in the crystallization tank are generated by the convection of the solution. And gas agitation crystallization method, wherein the crystals are stirred.

(Function and effect)
When bubbles rise in the crystallization tank, the liquid is first stirred by the bubbles themselves. Furthermore, liquid convection in the tank is generated in a form in which liquid and crystals are accompanied by rising bubbles. Thereby, stirring of a solution or a crystal slurry can be performed.

<Invention of Claim 3>
The gas is dissolved in the solution in advance, the solubility of the solution is reduced when the solution is supplied into the crystallization tank, the dissolved gas is vaporized, and the solution and the staying solution in the crystallization tank The gas lift crystallization method according to claim 1 or 2, wherein convection of crystals is generated.

(Function and effect)
The invention described in this section is an effective form particularly when the solubility of the gas in the solution changes greatly due to changes in pressure or temperature. In this form, the amount of gas generated in the crystallization tank is increased. As a result, the stirring action can be increased.

<Invention of Claim 4>
The dissolved gas in the solution is vaporized by bringing the inside of the crystallization tank into an adiabatic and reduced pressure state, the stirring is performed by the generated gas, and the heat insulation of the solution in the crystallization tank is performed by the vaporization. The gas lift crystallization method according to claim 3, wherein cooling is performed.

(Function and effect)
In a system suitable for cooling crystallization, the solution is cooled by latent heat of vaporization accompanying the vaporization of the dissolved gas, and at the same time, a stirring action by the gas can be obtained. The amount of gas generated in the crystallization tank can be increased by dissolving a gas that has a large latent heat of vaporization and a large change in solubility in the solution due to changes in pressure and temperature. Can be increased.

<Invention of Claim 5>
A circulation path for pressurizing gas by a pressurizing means, dissolving the gas in the solution, supplying the solution into the crystallization tank, and pressurizing the gas generated in the crystallization tank by the pressurizing means The gas lift crystallization method according to claim 3, wherein

(Function and effect)
Since pressurizing means such as a compressor is used and gas is circulated, the amount of soluble gas used as a utility can be reduced.

<Invention of Claim 6>
The gas lift crystallization method according to any one of claims 1 to 5, wherein the crystallization target is mixed xylene containing paraxylene, and paraxylene crystals are obtained therefrom.

(Function and effect)
By adiabatic cooling, large paraxylene crystals having high purity can be suitably obtained.

<Invention of Claim 7>
The gas lift crystallization method according to any one of claims 1 to 5, wherein the crystallization object is mixed hexane containing cyclohexane, and cyclohexane crystals are obtained therefrom.

(Function and effect)
By adiabatic cooling, large cyclohexane crystals with high purity can be suitably obtained.

<Invention of Claim 8>
Dissolving means for dissolving gas in the solution of the object to be crystallized, partition or draft tube provided in the crystallization tank, and the solution in which gas is dissolved in a part of the cross section in the lower region of the partition or draft tube And means for generating dissolved gas as a gas from the supplied solution,
The gas lift crystal device characterized in that the generated gas rises along the partition or draft tube.

(Function and effect)
When a draft tube is installed in the crystallization tank, if a gas-dissolved solution is supplied inside the crystallization tank, there is a significant difference in the gas hold-up inside and outside the draft tube due to the generation of gas mainly inside the draft tube. As a result, the apparent specific gravity of the crystal slurry is small inside the draft tube, and the apparent specific gravity of the crystal slurry is large outside the draft tube. A flow is generated.
In addition, the cross-sectional area in the draft tube relative to the total cross-sectional area in the horizontal direction of the crystallization tank, i.e., the area through which the generated gas rises and passes, is smaller than that when no draft tube is installed. Can be increased, and the stirring effect can be increased.

<Invention of Claim 9>
The gas lift type crystal apparatus according to claim 8, further comprising a solubility adjusting tank that adjusts the solubility of the dissolved gas before the solution is supplied into the crystallization tank.

(Function and effect)
For example, when a pressurized gas is dissolved in a solution and an attempt is made to obtain a stirring effect by the generated gas in the crystallization operation, or when cooling crystallization is performed by an adiabatic cooling effect, Fine crystals may be generated due to sudden pressure changes and temperature changes, and crystals generated at the supply location may be fixed and clogged.
On the other hand, the pressure and temperature of the liquid supplied to the crystallization tank are adjusted by installing a decompression vessel (solubility adjustment tank) for decompressing the solution to a predetermined pressure in the previous stage of the crystallization tank. It is possible to prevent the generation of fine crystals or the blockage of the supply location due to a rapid change.
In addition, when the gas generated in the crystallization tank is supplied to the compressor for circulation, for example, the residual pressure is supplied from the decompression vessel (solubility adjustment tank) to the compressor, thereby reducing the load on the compressor. can do. Therefore, the power of the compressor can be reduced, and the compressor can be downsized as compared with the case where a decompression vessel (solubility adjustment tank) is not installed. Can do.

  As described above, according to the present invention, a good circulation state in the crystallization tank can be obtained without installing a mechanical stirring mechanism in a crystallization operation accompanied by gas generation or by a small mechanical stirring mechanism. Obtainable. In particular, in a large facility for performing adiabatic cooling crystallization by the latent heat of vaporization of dissolved gas, it is possible to effectively reduce facility costs and operation costs. Furthermore, since the crystal can be prevented from being refined by a stirring mechanism, it is a great advantage that a large crystal can be obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
(First embodiment: basic form)
FIG. 1 shows a basic embodiment according to the present invention by an adiabatic cooling crystallization method, and includes an absorption capacitor 10, a solubility adjustment tank 20, a crystallization tank 30, a compressor 40, and a crystal purification means 50.
A compound mixed solution 1 (a solution of a crystallization target, for example, a solution of a eutectic multicomponent mixture containing para-xylene and its isomer) was led to an absorption capacitor 10, where it was led through a pipe 41. The refrigerant gas 4 (for example, propane) pressurized by the compressor 40 is absorbed to obtain a homogeneous mixed solution.
The mixed solution that has absorbed the refrigerant gas as a dissolved gas is introduced from the temporary storage tank 10A into the solubility adjusting tank 20 through the pipe 71, adjusted to a predetermined pressure and temperature, and then passed through the pipe 72 to the crystallization tank. The refrigerant gas is adiabatically cooled and evaporated with respect to the mixed solution containing the refrigerant gas.
The crystallization tank feed 60 for introducing the mixed solution containing the refrigerant gas into the crystallization tank 30 has a discharge end at the inside of the cylindrical draft tube 31 installed in the crystallization tank 30. It is supplied into the tube 31.
By such an operation, the refrigerant gas rises mainly as bubbles in the draft tube 31 (the rising region of the bubbles is shown in a pattern form in FIG. 2), and a difference occurs in gas hold-up inside and outside the draft tube 31. As a result, a difference occurs in the apparent specific gravity of the crystal slurry inside and outside the draft tube 31, and the convection of the slurry occurs in the crystallization tank 30 due to the specific gravity difference and the accompanying upward flow of the generated gas (convection is indicated by an arrow). ). By this convection, the liquid inside can be stirred without installing a stirring mechanism requiring external power in the crystallization tank 30.
The vapor generated in the crystallization tank 30 is sent to the mist separator 33 through the pipe line 33A and separated into a gas component and a liquid part, and the liquid part is returned to the crystallization tank 30 through the pipe line 33B. It is supplied to the suction of the compressor 40 by 33C.
In addition, the solubility adjusting tank 20 is provided with a pressure adjusting valve 21 and / or a temperature controller (not shown). For example, after the pressure is reduced to an appropriate pressure by the pressure adjusting valve 21, a mixed solution that has absorbed dissolved gas is crystallized in the crystallization tank 30. Send to. The refrigerant gas passing through the pressure regulating valve 21 is supplied to the middle suction of the compressor 40.
The crystal slurry generated in the crystallization tank 30 is supplied to a crystal purification means 50 (for example, a crystal washing tower), the crystal is purified, separated into the purified crystal melt 3 and the filtrate 2, and the crystal melt 3 Is made into a crystal product through an appropriate process.
The draft tube 31 is preferably cylindrical as shown in FIG. 3, but may have a square cross section. Further, instead of the draft tube 31, a partition 31A as shown in FIGS. 4 and 5 can be used.

(Other embodiments)
In the present invention, a form in which a local distribution of gas is generated in the solution in the crystallization tank and the convection of the solution is generated by the local distribution of the gas, and a convection of the solution is generated by the rise of the gas in the crystallization tank. As an aspect, various forms are included.
This is roughly divided into A. As shown in FIG. 9, the dissolved gas dissolved in the solution S supplied into the crystallization tank 30 is vaporized. As shown in FIG. 10, the gas is entrained in the solution S supplied into the crystallization tank 30, C.I. As shown in FIG. 11, in addition to the solution S supplied into the crystallization tank 30, the gas V is supplied (in this case, the dissolved gas dissolved in the solution S supplied into the crystallization tank 30. May be used in the form of vaporizing). Moreover, it can also employ | adopt combining these.
The first embodiment belongs to the A form, and a soluble gas is dissolved in a supply liquid under pressure in a preceding stage of the crystallization tank 30, and this is decompressed in the crystallization tank 30. It is the form which generates gas by doing.

Since the present invention includes various forms as described above, a more specific form will be exemplified below.
(1) A method of boiling the mixed solution and generating gas in the crystallization tank 30 before supplying the mixed solution or in the crystallization tank 30 FIG. 12 is heated in the previous stage of supplying the mixed solution to the crystallization tank 30 13 and 14 show a method of heating the mixed solution in the crystallization tank 30, respectively.
In the example of FIG. 12, the heat exchanger 80 is installed in the front | former stage of the crystallization tank feed 60, a mixed solution is heated, a solution is boiled and gas is generated. On the other hand, in the latter case, in the example of FIG. 13, an indirect heating type heat exchanger 81 is installed in the lower part outside the draft tube 31 in the crystallization tank 30, and the mixed solution is heated to boil the solution and generate gas. It is a form to be made. In the example of FIG. 14, an indirect heating type heat exchanger 81 is installed in the lower part of the inside of the draft tube 31, and the mixed solution is heated to boil the solution and generate gas. In addition, as the heat exchanger 81, it can replace by installing a jacket in piping. Moreover, steam, warm water, etc. can be used as a heat medium used for heating. In these examples, the draft tube 31 can be replaced with a partition plate. In the case of a partition plate, a heat exchanger 81 may be provided at the lower portion of the partition plate.

(2) Method of generating gas by lowering solubility of dissolved gas by adding third component, etc. As shown in FIG. 15, a line mixer 82 is installed upstream of the crystallization tank feed 60, In addition, the third component solution 83 is supplied to the solution, both are mixed by the line mixer 82, and the solubility of the dissolved gas is lowered to generate gas in the crystallization tank 30. The third component in this case is a solvent (component) that lowers the solubility of the gas in the solution.

(3) Method of generating gas by chemical reaction Although the apparatus configuration is substantially the same as the example in the previous paragraph, as shown in FIG. 16, a line mixer 82 is installed in the preceding stage of the crystallization tank feed 60, Before the line mixer 82, the gas generating reaction component 84 is supplied to the solution, both are mixed by the line mixer 82, and gas is generated to generate gas in the crystallization tank 30.

(4) Method of introducing gas from the outside using an apparatus such as a gas blower As shown in FIG. 17, a gas supply port 86 to which gas is supplied from a gas blower 85 is arranged separately from the crystallization tank feed 60. In addition, there is a method in which an upward flow of gas is generated either inside or outside the draft tube 31. Further, as shown in FIG. 18, gas can be introduced into the crystallization tank feed 60 by the gas blower 85, and the mixed solution and the introduced gas can be accompanied and supplied to the crystallization tank 30. The introduced gas used in this method is preferably one that is difficult to dissolve in the mixed solution. The gas used in this method can be recovered in the crystallization tank 30 and circulated again.

Hereinafter, the effect of the present invention will be clarified by showing examples.
Example 1
In the following examples, crystallization operation was performed by the process shown in FIGS. 1 to 3, and a vertical crystallizer (diameter 400 mm × height 1500 mm, slurry capacity 140 liters) was used as the crystallization tank 30. The absorption condenser 10 was a horizontal tube type, and the crystal purification means 50 was a piston type crystal washing tower.
A mixed xylene raw material containing 80-90% para-xylene is supplied to the absorption condenser 10 at a rate of 50-60 kg / hr, and propane pressurized to 0.2-0.9 MPaG by the compressor 40 is contact-mixed. And absorbed at about 30 ° C. The obtained absorption liquid was a mixed xylene solution of propane having a propane concentration of 10 to 50%, and this was introduced into the solubility adjustment tank 20 and decompressed to 0.1 to 0.5 MPaG. At this time, the mixed xylene solution was cooled to −5 to 10 ° C. by the adiabatic cooling effect of propane vaporized. The cooled mixed xylene solution is led to a crystallization tank 30 operated under atmospheric pressure, where it is further cooled to −15 to −5 ° C. by the adiabatic cooling effect due to vaporization of propane. Crystallization of para-xylene was attempted.
The mixed xylene solution supplied from the solubility adjusting tank 20 is guided to the inside of the draft tube 31 of the crystallization tank 30 by the crystallization tank feed 60, and the vaporization of propane gas is mainly generated inside the draft tube 31. It was confirmed from the sight glass 32 attached to the crystallization tank 30 that the slurry containing para-xylene crystals in 30 was an upward flow inside the draft tube 31 and a downward flow outside.
The obtained paraxylene crystal slurry was collected from the sampling nozzle 73, and the particle size of the paraxylene crystal was measured. As a result, a sufficiently large paraxylene crystal of 100 to 500 μm was obtained as shown in FIG. 8 (photograph). It was confirmed.
The obtained crystals were supplied to the piston type crystal washing tower 50 and subjected to solid-liquid separation and purification of paraxylene crystals. As a result, the paraxylene concentration in the filtrate 2 was 70 to 85%. It was confirmed that the paraxylene concentration in the liquid 3 was 99.7% or more.

(Example 2)
As can be seen from the solid-liquid equilibrium diagram in the propane-benzene-cyclohexane eutectic composition shown in FIG. 19, high-purity cyclohexane can be obtained by separation and purification by crystallization.
From FIG. 19, a solid-liquid equilibrium line of a binary system of cyclohexane and benzene is obtained. When the cyclohexane-rich mixed raw material is cooled to crystallize cyclohexane, it hits the solid-liquid line on the left side and starts crystallization. In the propane adiabatic cooling method, when the feed liquid and propane are mixed, the pressure is released, and cooling is started, the solid-liquid equilibrium line of the ternary system to which propane has been added (the line indicated by the broken line in FIG. 19. Is 0.3, the total molar fraction of benzene and cyclohexane excluding propane is shown to be 1), and when cooled to near the eutectic point, Crystals crystallize and these crystals are separated from the mother liquor. Then, the cyclohexane crystals and the separated mother liquor are depropanated, mixed with the raw materials, and fed back. In the crystallization operation of the propane adiabatic cooling method, propane becomes a gas in the supply liquid at the time of the pressure release operation, so that the stirring operation with the gas described above is possible.
When adiabatic cooling according to the present invention is carried out, a crystal having a crystal diameter (100 μm or more) and crystal purity equal to or greater than that of a crystal produced by an indirect cooling method generally performed in both crystal diameter and crystal purity can be obtained. It was.

(Example 3)
The paraxylene crystals obtained by indirect cooling and the paraxylene crystals obtained by adiabatic cooling according to the present invention were examined for differences in crystal grain size by examining the sedimentation properties of the crystals.
In the test, as shown in FIG. 6, the crystal slurry was put into a graduated cylinder, and the change with time of the interface position of the crystal bed was measured. The results are shown in FIG. According to the result, in the case of adiabatic cooling, the sedimentation rate of the crystals is fast, and the fast cause is that the crystal grain size by adiabatic cooling is larger than the crystal grain size by indirect cooling.

It is a flow sheet of a basic embodiment. It is a general | schematic longitudinal view of a crystallization tank. It is a 3-3 arrow line view. It is a general | schematic longitudinal view of the crystallization tank in the example using another partition plate. It is a 5-5 line arrow directional view. It is explanatory drawing of the sedimentation test of a crystal | crystallization. It is a graph of the result of a sedimentation test. It is a photograph of the paraxylene crystal | crystallization with a particle size of 100-500 micrometers. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a schematic diagram which shows the aspect of this invention. It is a solid-liquid equilibrium diagram in the eutectic composition of a propane-benzene-cyclohexane system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mixed xylene raw material, 2 ... Filtrate, 3 ... Crystal melt, 4 ... Propane make-up, 10 ... Absorption capacitor, 10A ... Temporary storage tank, 20 ... Solubility adjustment tank, 21 ... Pressure adjustment valve, 30 ... Crystallization tank 31 ... Draft tube, 31A ... Partition body, 33 ... Mist separator, 40 ... Compressor, 50 ... Crystal washing tower, 60 ... Crystallizer feed, 80 ... Heat exchanger, 81 ... Heat exchanger, 82 ... Line mixer 85 ... Gas blower.

Claims (10)

  The solution of the object to be crystallized is introduced into the crystallization tank, and a local distribution of gas is generated in the liquid in the crystallization tank, and due to the local distribution of the gas (by the convection of the solution in the tank, the solution And a gas lift crystallization method characterized by providing a stirrer effect of the staying solution and crystals in the crystallization tank.   The solution of the object to be crystallized is introduced into the crystallization tank, and convection of the solution is caused by gas rise in the crystallization tank, and the solution and the staying solution in the crystallization tank are generated by the convection of the solution. And gas agitation crystallization method, wherein the crystals are stirred.   The gas is dissolved in the solution in advance, the solubility of the solution is reduced when the solution is supplied into the crystallization tank, the dissolved gas is vaporized, and the solution and the staying solution in the crystallization tank The gas lift crystallization method according to claim 1 or 2, wherein convection of crystals is generated.   The dissolved gas in the solution is vaporized by bringing the inside of the crystallization tank into an adiabatic and reduced pressure state, the stirring is performed by the generated gas, and the heat insulation of the solution in the crystallization tank is performed by the vaporization. The gas lift crystallization method according to claim 3, wherein cooling is performed.   A circulation path for pressurizing gas by a pressurizing means, dissolving the gas in the solution, supplying the solution into the crystallization tank, and pressurizing the gas generated in the crystallization tank by the pressurizing means The gas lift crystallization method according to claim 3, wherein   The gas lift crystallization method according to any one of claims 1 to 5, wherein the crystallization object is mixed xylene containing paraxylene, and paraxylene crystals are obtained therefrom.   The gas lift crystallization method according to any one of claims 1 to 5, wherein the crystallization object is mixed hexane containing cyclohexane, and cyclohexane crystals are obtained therefrom. Dissolving means for dissolving gas in the solution of the object to be crystallized, partition or draft tube provided in the crystallization tank, and the solution in which gas is dissolved in a part of the cross section in the lower region of the partition or draft tube And means for generating dissolved gas as a gas from the supplied solution,
The gas lift crystal device characterized in that the generated gas rises along the partition or draft tube.   The gas lift type crystal apparatus according to claim 8, further comprising a solubility adjusting tank that adjusts the solubility of the dissolved gas before the solution is supplied into the crystallization tank.   The gas lift crystallization apparatus according to claim 8 or 9, comprising a dissolving means for pressurizing and dissolving the gas in the solution, and a circulation path for sending the gas generated in the crystallization tank to the dissolving means.

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