JP6256496B2 - Crystallizer and crystallization method - Google Patents

Description

  The present invention relates to a crystallization apparatus and a crystallization method for separating and filtering a contained material dissolved in various fluids by crystallization.

  One method for separating and purifying substances dissolved in various fluids is a method for separating and filtering the substances by crystallization. In general, crystallization uses a phenomenon in which a substance cannot be completely dissolved when it exceeds a concentration at which the substance can be dissolved, and is performed by changing pressure, temperature, etc. alone or in combination. Note that “crystallization” is a term originally used when crystallizing a target substance from a solution. Here, the reaction of obtaining a substance from a fluid is generically called crystallization. To do.

  As an industrial field where crystallization is used, it is used not only in the chemical and petroleum fields but also in the semiconductor and steel fields.

Non-Patent Document 1 describes in detail from the basic principle that a crystal is generated in a liquid to an applied device, in which succinic acid crystallization, KCl crystal growth and solute uptake are described. The growth of KAl (SO ₄ ) ₂ · 12H ₂ O and the like are described together with the apparatus.

  In such a crystallization apparatus, there is a problem that a crystallization product of the contained material is deposited on the inner wall of the reaction vessel in which the crystallization reaction is performed. When the contained material aggregates and solidifies on the wall surface, it stays attached to the wall surface, and further, the contained material accumulates on the wall surface and grows into a large lump, causing clogging of the device. In particular, when the contained material is solidified after contacting the wall surface in the liquid phase, the material adheres firmly to the wall surface, leading to clogging of the device and frequent maintenance for removing deposits.

  In order to solve such a problem, in Patent Document 1, the deposition preventing fluid is ejected from the inflow port of the reaction vessel, and the temperature control fluid is blown from the side surface of the reaction vessel, so that it is contained in the inflow port and the inner wall of the reaction vessel. A technique for reducing the phenomenon of aggregation and solidification of a substance is disclosed.

WO2014 / 020854

Nakai Susumu, Crystallization Engineering Chemical Engineering Series 9, Bafukan, pp. 6-51

  However, the apparatus disclosed in Patent Document 1 still has a problem that the contained substance aggregates and solidifies on the wall surface of the reaction vessel. When the contained material starts to aggregate and solidify on the wall surface of the reaction vessel, the contained material grows and adheres to the wall surface in a large amount. In the worst case, clogging occurs in the reaction vessel. Therefore, it is necessary to frequently clean the inside of the reaction container.

  The present invention has been made for such a problem, and provides a crystallization apparatus and a crystallization method capable of suppressing aggregation and solidification of contained substances on the wall surface of a reaction vessel and reducing maintenance frequency. The purpose is to provide.

In order to achieve the above object, the present invention has the following features.
[1] In a crystallization apparatus for supplying a fluid to a reaction vessel and changing at least one of temperature and pressure in the reaction vessel to crystallize a substance contained in the fluid.
A cylindrical reaction vessel in which fluid is supplied from one end and fluid is discharged from the other end;
A crystallizer comprising: a seed material supply means for supplying a carrier fluid containing solid particles as a seed material into the reaction container from a side surface of the reaction container.
[2] provided on the outlet side of the reaction vessel, further comprising a recovery means for recovering the crystallized contained material from the fluid discharged from the reaction vessel and discharging the fluid after collecting the contained material;
The seed substance supply unit supplies the part of the fluid discharged from the recovery unit into the reaction vessel as a carrier fluid containing solid particles to be the seed substance, according to [1].
[3] The crystallization apparatus according to [1] or [2], wherein the seed material supply means supplies the carrier fluid containing solid particles having a particle size of 1000 μm or less, which becomes the seed material, into the reaction vessel.
[4] In a crystallization method in which a fluid is supplied to a reaction vessel and at least one of temperature and pressure in the reaction vessel is changed to crystallize a substance contained in the fluid.
Supply fluid from one end of cylindrical reaction vessel,
A crystallization method in which at least one of temperature and pressure in the reaction vessel is changed by supplying a carrier fluid containing solid particles as a seed material into the reaction vessel from the side of the reaction vessel.
[5] From the fluid discharged from the other end of the reaction vessel, the crystallized contained material is recovered,
The crystallization method according to [4], wherein a part of the fluid from which the contained material is recovered is supplied from the side wall of the reaction vessel as a carrier fluid containing solid particles as the seed material.
[6] The crystallization method according to [4] or [5], wherein a carrier fluid containing solid particles having a particle size of 1000 μm or less that serves as a seed material is supplied into the reaction vessel.
[7] The crystallization method according to any one of [4] to [6], which is used in a process for producing a silicon steel sheet by siliconization.

  According to the crystallization apparatus and the crystallization method of the present invention, the carrier fluid containing the solid particles as the seed material is supplied into the reaction vessel from the side surface of the reaction vessel, thereby aggregating the contained material on the wall surface. Solidification can be suppressed and maintenance frequency can be reduced.

It is a figure which shows the structure of the crystallization apparatus which concerns on embodiment of this invention. It is a figure which shows the influence of the seed material particle diameter which acts on the wall surface adhesion amount. It is a figure which shows the other structure of the crystallization apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the structure of the crystallization apparatus (crystallization apparatus shown by FIG. 1) which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a configuration of a crystallization apparatus 1 according to Embodiment 1 of the present invention. First, an outline of the present invention will be described. The crystallization apparatus 1 is an apparatus for changing the temperature and pressure in the reaction vessel 2 to crystallize the contained material contained in the supplied fluid 10 and recovering the crystallized product. is there.

  For example, such a crystallization apparatus 1 is used for recovering a contained substance from the fluid 10 when the contained substance cannot be discharged to the outside as it is due to environmental problems.

  The crystallizer 1 has a control device and a function (not shown) that change at least one of the temperature and pressure in the reaction vessel 2. In the crystallization apparatus 1, the carrier fluid is supplied into the reaction vessel 2, thereby changing at least one of the temperature and pressure in the reaction vessel 2 to crystallize the contained material contained in the fluid 10. To recover the contained material.

  First, description will be made assuming that the fluid 10 is a gas. Further, the case where the contained substance is a gas at a high temperature but becomes a solid at a low temperature (for example, room temperature) and temperature control in the reaction vessel 2 is performed will be described as an example.

  The fluid 10 containing the contained material is introduced into the reaction vessel 2. At this time, if the fluid 10 is a kind of gas that does not react with the contained substance, it can be used. Further, when the fluid 10 is introduced into the reaction vessel 2, the temperature is high enough that the contained substance can maintain a gaseous state.

  Next, when the temperature of the fluid 10 is decreased from a high temperature, the contained material condenses and solidifies as the temperature decreases, and precipitates as a solid. The temperature at which condensation and solidification vary depending on the substance, but in any case, when the solid substance is deposited on the wall surface in the reaction vessel 2, the contained substance grows based on the precipitated solid. A large amount of contained material adheres to the wall surface.

  Here, in order to prevent the contained material in the reaction vessel 2 from adhering to the wall surface, it is effective to condense and solidify the contained material in the air before the fluid 10 containing the contained material contacts the wall surface. When the contained substance condenses and solidifies in the air, it quickly becomes a powder and falls quickly, so that it can be easily discharged out of the reaction vessel 2 without causing clogging due to adhesion. Therefore, in the present invention, in order to efficiently condense and solidify the contained material in the reaction vessel 2, a seed material that is a solid material that becomes an agglomeration nucleus of the contained material is mixed into the carrier fluid, and this carrier fluid is used as the reaction vessel. 2 is fed into the reaction vessel 2 from the side surface.

  By supplying the carrier fluid containing the seed material from the side surface of the reaction vessel 2, the seed material is transported from the side surface of the reaction vessel 2 to the center side to induce crystallization near the center in the reaction vessel 2, and adhere to the wall surface. It becomes possible to crystallize the contained material as a solid before.

Furthermore, in the present invention, as the carrier fluid containing the seed material, a part of the fluid after the contained material crystallized from the fluid 10 is recovered is circulated and supplied to the reaction vessel 2. The flow bodies containing material was recovered, but contains residual-containing material without being recovered, it is possible to utilize this remaining-containing material as a seed material.

  When a substance different from the contained substance is used as the seed substance, a step of further separating the contained substance and the seed substance on the exit side of the reaction container 2 is required. In the present invention, the fluid discharged from the reaction container 2 is used as the seed substance. It is possible to improve the crystallization efficiency without increasing the separation step as described above by using the carrier fluid as a carrier fluid by circulating it and using the contained substance contained in the carrier fluid as a seed material.

  Next, each structure of the crystallization apparatus 1 which concerns on this invention is demonstrated. The crystallizer 1 includes a reaction vessel 2, a recovery device 3, a gas amount control device 4, and a carrier fluid supply pipe 5.

  The reaction vessel 2 has a cylindrical shape installed vertically. The reaction vessel 2 is supplied with the fluid 10 from one end (upper side), and the crystallized product 11 and the fluid 10 from which the contained substance is crystallized are discharged from the other end (lower side). The reaction vessel 2 has a cylindrical portion 2b having a constant diameter, and an upper tapered portion 2a and a lower tapered portion 2c provided above and below the cylindrical portion 2b. The upper tapered portion 2a has a diameter that decreases upward. On the other hand, the diameter of the lower tapered portion 2c decreases as it goes downward.

  A seed material supply means 21 is provided in the cylindrical portion 2b of the reaction vessel 2 at a predetermined interval in the circumferential direction. The seed material supply means 21 supplies a carrier fluid containing solid particles as a seed material into the reaction vessel 2. The seed material supply means 21 injects the carrier fluid at an injection angle so that the carrier fluid rotates inside the cylindrical portion 2b. By ejecting the carrier fluid in this manner, a whirling flow is generated, the time for retaining the fluid 10 in the cylindrical portion 2b is lengthened, and the reaction time for the crystallization reaction is lengthened. The seed substance supply means 21 carries the seed substance to the vicinity of the center of the reaction container 2 by supplying a carrier fluid mixed with the seed substance from the side surface of the reaction container 2, so that the seed substance is supplied to the center of the reaction container 2. Induces crystallization in the air.

  The injection angle, injection amount, and speed of the carrier fluid by the seed material supply means 21 need to be adjusted so as to improve the crystallization reaction efficiency and to prevent the crystallization product 11 from adhering or depositing. However, since the injection angle, speed, and amount depend on the respective crystallizers, they cannot be generally specified and must be determined for each crystallizer.

  The recovery device 3 is provided on the outlet side of the reaction vessel 2 and collects the crystallized product 11 discharged from the reaction vessel 2 and discharges the fluid after recovering the crystallized product 11. The collection device 3 is configured by, for example, a screw conveyor. Specifically, the recovery device 3 includes a screw shaft 31 and a spiral plate member 32 attached along the screw shaft 31. The collection device 3 rotates the screw shaft 31 to convey the crystallized material 11 from the left side to the right side along the spiral plate member 32. One end of the recovery device 3 has an introduction port connected to the reaction vessel 2, and the other end is provided with a discharge port for recovering the crystallized product 11. The crystallized substance 11 is introduced into the recovery device 3 from the introduction port, conveyed by a screw conveyor, and recovered from the discharge port.

  The gas amount control device 4 is supplied with the fluid after recovering the crystallized product 11. The gas amount control device 4 separates a part of the fluid after recovering the crystallized substance 11 and supplies it to the seed material supply means 21 via the carrier fluid supply pipe 5. This separated fluid functions as a carrier fluid. In addition, the gas amount control device 4 adjusts the flow rate of the carrier fluid. In the carrier fluid, the contained material that could not be recovered as the crystallized substance 11 remains, but the remaining contained material functions as solid particles serving as a seed material.

  In order to recover the contained substances contained in the exhausted fluid that could not be recovered, they are removed by a commonly used means such as a filter or centrifugal separation.

  As shown in FIG. 3, a carrier fluid supply device 6 for supplying a carrier fluid and a seed material supply device 7 for supplying a seed material may be separately installed in the middle of the carrier fluid supply pipe 5 as necessary. .

  As described above, in the present invention, by supplying a carrier fluid containing solid particles as a seed material to the reaction vessel 2 from the side surface of the reaction vessel 2, crystallization is promoted at the center rather than the side surface of the reaction vessel 2, Aggregation and coagulation of the contained substances on the wall surface of the reaction vessel 2 can be suppressed, and the maintenance frequency can be reduced.

  Further, in the present invention, a part of the fluid discharged from the reaction vessel 2 is circulated and used as a carrier fluid, and the contained substance contained in the carrier fluid is used as a seed material, so that a crystal is produced on the outlet side of the reaction vessel 2. Crystallization efficiency can be improved without providing a step of separating the precipitate 11 and the seed material.

  The above explanation is an example in the case where the temperature in the reaction vessel 2 is changed, but the same is true when the pressure is changed. When changing the pressure, the reaction vessel 2 is configured to have a high pressure on the inlet side of the reaction vessel 2 and a low pressure on the outlet side. When the pressure is lowered, the solubility of the contained substance in the fluid 10 is lowered, so that the contained substance is condensed and solidified.

  A change in temperature and a change in pressure may be used in combination.

  Moreover, even if the fluid 10 is the same substance as the contained substance, the present invention can be applied in exactly the same manner.

  When the fluid containing the contained substance is a liquid, it is preferable to use the same fluid as the fluid containing the contained substance as the carrier fluid. At that time, a substance for controlling crystallization may be added. For example, ceramic fine particles that do not dissolve in the liquid may be mixed into the fluid as a seed material. Even in the case of a liquid, it is necessary to determine a good range of the injection angle, the injection amount, and the velocity using numerical analysis, experiments, and the like.

  If the diameter of the seed material is too large, it will drop immediately due to its own weight, so it cannot be scattered in the carrier fluid. The upper limit of the diameter of the seed material that is stably mixed and scattered with the carrier fluid is about 1000 μm although it depends on the flow rate and flow velocity of the carrier fluid. In addition, since the seed material has a smaller diameter and a larger number of grains, the effect of diffusing and promoting crystallization is higher. Therefore, there is no need to set a lower limit of the grain size, but the formation state of the crystallized product according to the present invention is considered. For example, the lower limit of the particle size of the seed material is about 0.01 μm. The adjustment of the particle size of the seed material contained in the carrier fluid can be performed by passing the carrier fluid through an appropriate filter. The particle size can be determined, for example, by a sieving method (JIS8801).

The crystallization apparatus and the crystallization method according to the present invention are particularly preferably used for a process (for example, continuous siliconization line) for producing a silicon steel sheet by siliconization. Specifically, when a steel sheet containing silicon is produced by a continuous siliconization line, a gas containing FeCl ₂ is produced as a by-product. The gas containing FeCl ₂ is treated as the fluid 10 by the crystallization apparatus and the crystallization method according to the present invention, thereby performing the crystallization treatment while suppressing the aggregation and solidification of the contained substances on the wall of the reaction vessel. Can do.

Using the apparatus shown in FIG. 1, separation / recovery experiment of FeCl ₂ was performed. FeCl _{2 has} a freezing point of 677 ° C and a boiling point of 1023 ° C.

In the example of the present invention, nitrogen gas containing FeCl ₂ (gas) was introduced as the fluid 10 from above the reaction vessel 2 at a temperature of 1200 ° C. and a flow rate of 500 Nm ³ / h. As the carrier fluid, the remaining fluid from which the crystallized product 11 was recovered was used and charged at 550 Nm ³ / h from the seed material supply means 21 at room temperature. In another example of the present invention, the same experiment was performed using Ar or a mixed gas of N ₂ and Ar instead of N ₂ which is a carrier fluid, and Al ₂ O ₃ instead of FeCl ₂ which is a seed material. A similar experiment was performed using CuO.

  Table 1 shows the experimental results.

  No. of the conventional example which did not throw in a seed material. Compared with No. 1, No. 1 into which the seed material was introduced. In 2-12, it turns out that the amount of wall surface adhesion has decreased. That is, it can be seen that by applying the present invention, the adhesion of iron chloride to the wall surface can be reduced, and powdered iron chloride can be recovered outside the apparatus. Moreover, the wall surface adhesion amount was almost the same regardless of the type of carrier fluid. It can be said that the crystallization efficiency does not depend on the type of seed material, since the amount of adhesion is reduced regardless of which seed material is used.

Next, the experiment was performed by changing the particle size of the seed material to 0.5 to 1500 μm. At this time, the weight of the seed material to be added was fixed to 0.003 kg / s regardless of the particle diameter. That is, when the particle size was changed, the number of particles to be simultaneously added was also changed. The particle size of the particles was adjusted by providing a filter in the flow path before introducing the carrier gas into the apparatus. In the apparatus used in the present invention, FeCl ₂ gradually accumulates in the apparatus with the operation, and the crystallization efficiency is lowered. Therefore, maintenance for periodically removing FeCl ₂ is required. When operation is carried out without introducing seed materials, maintenance is carried out once every four days, putting pressure on the operation. In the present invention, the range of the particle size that can extend the maintenance interval to 10 days or more is set to a particularly appropriate range. If the maintenance interval is 10 days or more, operation can be performed without reducing efficiency.

  FIG. 2 shows the influence of the seed material particle size on the wall surface adhesion amount. FIG. 2 shows the results of numbers 2 and 7 to 12 among the examples shown in Table 1. The smaller the seed material particle size, the lower the wall deposition. This is presumably because the aggregation of iron chloride can be promoted because the smaller the particle size and the greater the number, the easier it is to diffuse in the carrier fluid and in the reaction vessel 2. In addition, the upper limit of the wall surface adhesion amount that can extend the maintenance interval described above to 10 days or more was about 1200 g / day.

  Table 1 shows the survey results of the maintenance intervals of the equipment. In the comparative example (No. 1 in Table 1) in which no seed material was used, the maintenance of the apparatus was performed once every four days. However, when the present invention is applied, the wall surface adhesion amount of the contained substance is reduced, the number of times of stopping and cleaning / maintening the inside of the apparatus can be reduced, and the operation efficiency is greatly improved. In particular, the particle size of the seed material that can extend the maintenance interval to 10 days or more was 1000 μm or less.

DESCRIPTION OF SYMBOLS 1 Crystallizer 2 Reaction container 2a Upper taper part 2b Cylindrical part 2c Lower taper part 21 Seed substance supply means 3 Recovery apparatus 31 Screw shaft 32 Plate member 4 Gas amount control apparatus 5 Carrier fluid supply pipe 6 Carrier fluid supply apparatus 7 Seed substance Supply device 8 Species substance 10 Fluid 11 Crystallized product

Claims (7)

In a crystallization apparatus for supplying a fluid to a reaction vessel and changing at least one of temperature and pressure in the reaction vessel to crystallize a substance contained in the fluid.
A vertically installed cylindrical reaction vessel in which fluid is supplied from one end on the upper side and fluid is discharged from the other end on the lower side ;
A seed material supply means for supplying a carrier fluid containing solid particles as a seed material into the reaction container from the side of the reaction container ,
The seed material supply means is provided at a predetermined interval in the circumferential direction of the side surface of the reaction vessel, and injects the carrier fluid at an injection angle so that the carrier fluid rotates inside the reaction vessel. Crystallizer. Provided on the outlet side of the reaction vessel, further comprising a collection means for collecting the crystallized contained material from the fluid discharged from the reaction vessel and discharging the fluid after collecting the contained material;
The crystallization apparatus according to claim 1, wherein the seed substance supply means supplies a part of the fluid discharged from the recovery means into the reaction vessel as a carrier fluid containing solid particles as the seed substance.   The crystallization apparatus according to claim 1 or 2, wherein the seed material supply means supplies a carrier fluid containing solid particles having a particle size of 1000 µm or less as a seed material into the reaction vessel. In a crystallization method in which a fluid is supplied to a reaction vessel and at least one of temperature and pressure in the reaction vessel is changed to crystallize a substance contained in the fluid.
Supply fluid from one end on the upper side of a cylindrical reaction vessel installed vertically ,
A carrier fluid containing solid particles as a seed material is sprayed from the side surface of the reaction vessel so that the inside of the reaction vessel is rotated by a seed material supply means provided at a predetermined interval in the circumferential direction of the side surface of the reaction vessel. A crystallization method in which at least one of a temperature and a pressure in the reaction vessel is changed by supplying it into the reaction vessel at an included angle . From the fluid discharged from the other end on the lower side of the reaction vessel, the crystallized contained material is recovered,
Some of the fluid was recovered containing material, crystallization method according to claim 4 supplied from the side surface of the reaction vessel as a carrier fluid containing solid particles as a seed material.   The crystallization method according to claim 4 or 5, wherein a carrier fluid containing solid particles having a particle size of 1000 µm or less as a seed material is supplied into the reaction vessel. The crystallization method according to any one of claims 4 to 6 , wherein FeCl _{2 in} a gas generated when a silicon steel sheet is produced by siliconization is crystallized .

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