JP5906911B2 - Sodium separator - Google Patents

Description

  The present invention relates to a sodium separator for separating sodium and impurities contained in the sodium.

  As one of the methods for producing gallium nitride (GaN), which is expected as a next-generation semiconductor material, a crystal carrier is immersed in a Na / Ga melt at 700 ° C. to 1100 ° C. in a high-pressure nitrogen atmosphere of several MPa, and the crystal A crystal growth method (so-called sodium flux method) for growing a GaN crystal on a support is known. In this method, since liquid phase sodium is used as a fluxing agent, it is necessary to use high-purity sodium that has almost no impurities that hinder crystal growth.

  Conventionally, there is an apparatus called a cold trap as an apparatus for removing impurities from sodium (see Patent Document 1). This device uses the difference in saturation solubility due to temperature drop by pumping molten sodium of about 200 ° C with an electromagnetic pump or the like and supplying it to an impurity trapping part made of mesh packing whose temperature is controlled to about 120 ° C. The impurities contained in the sodium are deposited and recovered.

JP 2010-19592 A

  By the way, the cold trap is used in a large apparatus such as a fast breeder reactor using a large amount of molten sodium as a coolant, and an electromagnetic pump or the like is used for the flow of molten sodium. However, in a small apparatus such as a GaN crystal growth apparatus, since molten sodium is a small amount of about several liters, it is difficult to flow molten sodium with a large one such as an electromagnetic pump. In order to flow such a small amount of molten sodium, it is necessary to control a minute flow rate using a large number of devices, and the apparatus configuration becomes complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sodium separation device that can effectively separate sodium and impurities even in a small amount.

  In order to solve the above problems, the present invention provides a sodium separation device for separating sodium and impurities contained in the sodium, the tank having a storage space for storing sodium, and the temperature in the storage space. A temperature controller that performs adjustment; and a net-like member provided in the accommodation space, wherein the tank includes an impurity discharge portion provided at a bottom portion, and a sodium extraction provided above the impurity discharge portion. The structure of having a part is adopted.

  In the present invention, the temperature adjuster is provided at a height corresponding to the mesh member, and is provided above the mesh member, a first temperature adjustment unit that adjusts the temperature to a first temperature, And a second temperature adjusting unit that adjusts the temperature to a second temperature higher than the first temperature.

  Moreover, in this invention, the structure that the bottom part of the said tank inclines below toward the said impurity discharge part is employ | adopted.

  Moreover, in this invention, the structure of having a gas supply apparatus which supplies gas to the said accommodation space is employ | adopted.

  In the present invention, a configuration is adopted in which an ultrasonic vibrator that applies vibration to the mesh member is provided.

  In the present invention, the mesh member includes a dense portion formed at a first density and a rough portion formed at a second density lower than the first density and stacked above and below the dense portion. And adopting a configuration in which the sodium extraction part is provided at a height corresponding to the dense part.

  Moreover, in this invention, the said tank has the structure of having a 2nd impurity discharge part provided above the said mesh member.

According to the present invention, the sodium contained in the tank is melted by the temperature controller, the molten sodium is allowed to stand in the tank for a predetermined residence time, and impurities in sodium are made into the net-like member by utilizing the difference in saturation solubility. It can be deposited. Further, since impurities (oxygenates, hydrides, carbonates, etc.) are likely to sink, impurities can be discharged from the impurity discharge section at the bottom of the tank, and high-purity sodium can be extracted from the sodium extraction section above where there are few impurities.
Therefore, in the present invention, since impurities can be separated in a state where sodium is left without flowing, sodium and impurities can be effectively separated even in a small amount.

It is a block diagram which shows the sodium separation apparatus in 1st Embodiment of this invention. It is a block diagram which shows the sodium separation apparatus in 2nd Embodiment of this invention. It is a block diagram which shows the sodium separation apparatus in 3rd Embodiment of this invention. It is a block diagram which shows the sodium separation apparatus in 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram showing a sodium separation device 1 according to the first embodiment of the present invention.
The sodium separation apparatus 1 collects impurities (oxygenates, hydrides, carbonates, and other foreign matters) contained in the sodium A in the mesh member 4 by retaining the molten sodium A in the tank 2 for a predetermined time. It is a stationary device that separates high-purity sodium A and impurities.

The sodium separation device 1 includes a tank 2, a temperature regulator 3, a mesh member 4, an impurity discharge unit 5, and a sodium extraction unit 6.
The tank 2 has a storage space S for storing sodium A. The amount of sodium A that can be accommodated in the accommodation space S of the present embodiment is about several liters (L). The tank 2 has a bottomed cylindrical tank body 2a and a tank lid 2b that closes an upper opening of the tank body 2a.

  The temperature adjuster 3 performs temperature adjustment in the accommodation space S. The temperature adjuster 3 is provided outside the tank 2 and is configured to adjust the temperature in the accommodation space S by heat conduction through the wall of the tank 2. The temperature regulator 3 includes an electric heater or the like whose output can be adjusted. The temperature regulator 3 is provided so as to surround the side wall 2 a 2 of the tank 2 above the bottom 2 a 1 of the tank 2. The upper end of the temperature regulator 3 extends upward from the mesh member 4.

  The mesh member 4 is provided in the lower half of the accommodation space S. The mesh member 4 of the present embodiment is configured by laminating a plurality of mesh-shaped woven wire mesh, punching metal, expanded metal, and the like in the height direction. The mesh size of the mesh member 4 is relatively coarse considering the ease of staying of molten sodium A and the difficulty of clogging during impurity precipitation, for example, several to several tens of millimeters (mm). Preferably. The mesh member 4 of the present embodiment is formed by integrating and filling a plurality of metal meshes made of SUS (stainless steel). According to this configuration, the mesh member 4 can be easily replaced.

The impurity discharge part 5 is provided in the bottom part 2 a 1 of the tank 2. The impurity discharge unit 5 discharges impurities that have sunk in the bottom 2 a 1 of the tank 2. The impurity discharge unit 5 includes a pipe 5a connected to the bottom 2a1 of the tank 2 and a valve 5b that opens and closes the flow path of the pipe 5a.
The sodium extraction part 6 is provided above the impurity discharge part 5. The sodium extraction part 6 extracts the separated high purity sodium. The sodium extraction part 6 has the piping 6a connected to the side wall part 2a2 of the tank 2, and the valve 6b which opens and closes the flow path of the piping 6a.

  Separation of sodium and impurities by the sodium separator 1 having the above-described configuration is performed as follows.

  First, the tank lid 2b is opened, and sodium A is introduced from the upper opening of the tank body 2a. In this embodiment, sodium A is introduced as a solid, but sodium A that has been previously melted may be introduced. When sodium A is introduced, the tank lid 2b is closed, the upper opening of the tank body 2a is closed, and a sealed housing space S is formed.

  Next, the sodium A accommodated in the accommodation space S is melted. Specifically, the accommodation space S is heated to about 200 ° C. with the temperature regulator 3 to completely melt the sodium A. Since the upper end of the temperature regulator 3 of the present embodiment extends above the mesh member 4, heat can be efficiently applied to the solid sodium A riding on the mesh member 4.

  When the sodium A is melted, the temperature of the temperature regulator 3 is adjusted to lower the temperature of the housing space S from 200 ° C. to about 120 ° C. to 150 ° C. (sodium melting point or higher), and the temperature is maintained. Then, it is allowed to stand at that temperature for a predetermined residence time (several tens of hours to several tens of hours), so that impurities in sodium A are deposited on the mesh member 4. Since the temperature regulator 3 is provided at a height corresponding to the mesh member 4, the temperature of the mesh member 4 can be easily adjusted to about 120 ° C to 150 ° C.

  When sodium A reaches the saturation solubility of impurities due to a temperature drop due to contact with the mesh member 4, impurities that are not completely dissolved are deposited on the mesh member 4 and collected. Precipitated impurities (oxygenates, hydrides, carbonates, and other foreign substances) have a specific gravity greater than that of the molten sodium A, and those not collected by the mesh member 4 sink to the bottom 2a1 of the tank 2. Conversely, molten sodium A from which impurities have been removed is stored above the bottom 2a1 where the impurities sink.

  The sodium extraction part 6 is provided in the side wall part 2a2 of the tank 2 above the bottom part 2a1. For this reason, when the valve 6b is opened, the sodium A from which impurities have been removed can be taken out from the tank 2 through the pipe 6a. Moreover, since the sodium extraction part 6 is provided in the position corresponding to the lower end part of the mesh member 4, the energy by a water head can fully be utilized, and the impurity which sank in the bottom 2a1 by the mesh filter function of the mesh member 4 Even if it rolls up, the outflow from the sodium extraction part 6 can be prevented.

The bottom 2a1 is provided with an impurity discharge portion 5. Since impurities easily sink to the bottom 2a1, when the valve 5b is opened, the impurities can be discharged from the tank 2 through the pipe 5a.
Thus, according to this embodiment, the sodium A accommodated in the tank 2 is melted by the temperature regulator 3, and the molten sodium A is left in the tank 2 for a predetermined residence time, and the difference in saturation solubility is utilized. Then, impurities in sodium A are precipitated on the mesh member 4, and the impurities are discharged from the bottom 2a1 of the tank 2, and high-purity sodium A can be taken out from the sodium extraction portion 6 in the upper portion where there are few impurities. Therefore, in the present embodiment, since the impurities can be separated in a state where the sodium A is allowed to flow without flowing, the sodium A and the impurities can be effectively separated even in a small amount.

  Therefore, according to the above-described embodiment, the sodium separation device 1 for separating sodium A and impurities contained in the sodium A, the tank 2 having the storage space S for storing the sodium A, and the storage The tank 2 includes a temperature regulator 3 that regulates the temperature in the space S and a mesh member 4 provided in the accommodation space S. The tank 2 includes an impurity discharge unit 5 provided in the bottom 2 a 1 and an impurity discharge unit 5. In addition, by adopting the configuration of having the sodium extraction portion 6 provided on the upper side, sodium and impurities can be effectively separated even in a small amount.

  Further, according to the above-described embodiment, the apparatus can be made compact by providing the tank 2 with the sodium storage function and the impurity collecting function. Further, since a drive mechanism for flowing sodium is not necessary, control of a minute flow rate is not necessary. Moreover, since the residence time can be easily lengthened, the removal rate of impurities can be increased.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 2 is a configuration diagram showing the sodium separation device 1 according to the second embodiment of the present invention.
As shown in FIG. 2, the second embodiment differs from the above embodiment in that the temperature regulator 3 includes a first temperature adjustment unit 3 </ b> A and a second temperature adjustment unit 3 </ b> B. Further, the second embodiment is different from the above-described embodiment in that the sodium extraction portion 6 is provided above the mesh member 4 and near the upper end of the mesh member 4.

  The first temperature adjustment unit 3 </ b> A is provided at a height corresponding to the mesh member 4. The first temperature adjustment unit 3 </ b> A extends from the upper end of the mesh member 4 to the bottom 2 a 1 below the lower end of the mesh member 4. 3 A of 1st temperature adjustment parts consist of an electric heater etc. which can adjust output, and become the structure which adjusts the accommodation space S in installation height to 1st temperature. The first temperature of the present embodiment is set to a relatively low temperature (for example, about 120 ° C. to 150 ° C.) at which impurities are deposited.

  The second temperature adjustment unit 3 </ b> B is provided above the mesh member 4. The upper end of the second temperature adjustment unit 3B extends above the liquid level of sodium A. 3 A of 1st temperature adjustment parts consist of an electric heater etc. which can adjust output, and become the structure which adjusts the accommodation space S in installation height to 2nd temperature higher than 1st temperature. The second temperature of the present embodiment is set to a relatively high temperature (for example, about 150 ° C. to 180 ° C.) that improves the fluidity of the molten sodium A.

  According to the second embodiment having the above-described configuration, it is possible to form a temperature distribution in the accommodating space S that accommodates the sodium A by utilizing the fact that the present apparatus is a stationary type in which the sodium A does not flow. That is, at the lower part of the tank 2, the temperature is adjusted to a low temperature by the first temperature adjusting unit 3A and impurities are deposited by the mesh member 4, while at the upper part of the tank 2, the temperature is adjusted to a high temperature by the second temperature adjusting unit 3B. Thus, the fluidity of the molten sodium A from which impurities are removed can be enhanced.

  By increasing the fluidity of sodium A in the upper part of the tank 2, it is possible to make it easier to take out the sodium A from the sodium extraction part 6. Further, even when solid sodium A is additionally added, heat can be efficiently applied to the solid sodium A riding on the mesh member 4 by the second temperature adjusting unit 3B. In addition, since the roles can be shared between the first temperature adjustment unit 3A (impurity precipitation) and the second temperature adjustment unit 3B (sodium melting, fluidity securing), the output is output by one heater as in the above embodiment. The need for frequent variable adjustments is eliminated.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 3 is a configuration diagram showing the sodium separation device 1 according to the third embodiment of the present invention.
As shown in FIG. 3, the third embodiment is different from the above embodiment in that the bottom 2 a 1 of the tank 2 is inclined downward toward the impurity discharge unit 5. The third embodiment is different from the above-described embodiment in that the gas supply device 7 is provided. Further, the third embodiment is different from the above-described embodiment in that the ultrasonic vibrator 8 is provided.

The bottom 2a1 of the tank 2 of the third embodiment has a tapered shape that decreases in diameter as it goes downward, and an impurity discharge portion 5 is provided at the tip thereof.
The gas supply device 7 supplies gas to the tank 2 and applies pressure to the accommodation space S. The gas supply device 7 is configured to supply gas to the accommodation space S through a pipe (not shown) that penetrates the tank lid 2b in the thickness direction. As the gas supply device 7, a gas pump can be employed, and it is preferable to use an inert gas (nitrogen gas, argon gas, etc.) that does not generate impurities such as oxygenates as the gas.

  The ultrasonic vibrator 8 imparts vibration to the mesh member 4. The ultrasonic transducer 8 is provided at a height corresponding to the mesh member 4. The ultrasonic transducer 8 is provided on the side wall 2a2 of the tank 2, and is configured to ultrasonically vibrate the mesh member 4 through the side wall 2a2. One ultrasonic transducer 8 may be provided, or a plurality of ultrasonic transducers 8 may be provided at predetermined intervals in the circumferential direction.

  According to the third embodiment having the above-described configuration, the bottom 2a1 of the tank 2 is inclined downward toward the impurity discharge part 5, so that the settled impurities are collected by the inclination and the pipe 5a of the impurity discharge part 5 is connected. Accumulate in position. For this reason, impurities can be easily discharged from the tank 2 through the pipe 5a. Further, since impurities are accumulated at the bottom 2a1 of the tank 2 due to the inclination, the impurities are difficult to flow out from the sodium extraction portion 6.

  In addition, according to the third embodiment, since the gas supply device 7 that supplies gas to the accommodation space S is provided, impurities precipitate on the mesh member 4, thereby reducing the fluidity of the molten sodium A in the mesh member 4. Even so, by depressing the liquid surface with the gas pressure, the sodium A from which impurities have been removed can be easily taken out from the tank 2 through the pipe 6a.

  Further, according to the third embodiment, the ultrasonic vibrator 8 for applying vibration to the mesh member 4 is provided. Therefore, by applying vibration to the mesh member 4, the molten sodium A per unit time with respect to the mesh member 4 is obtained. The contact area (contact amount) can be increased. When the contact area per unit time with the mesh member 4 adjusted to a predetermined temperature (about 120 ° C. to about 150 ° C.) increases, impurities of molten sodium A are likely to precipitate, and the residence time in the tank 2 is shortened. Can be achieved.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 4 is a configuration diagram showing the sodium separation device 1 according to the fourth embodiment of the present invention.
In 4th Embodiment, as shown in FIG. 4, the net-like member 4 differs from the said embodiment by the point which has the dense part 4a and the rough part 4b. Further, the fourth embodiment is different from the above-described embodiment in that the second impurity discharge section 9 is provided.

  The mesh member 4 of the fourth embodiment has a three-layer structure, and is formed with a dense portion 4a formed with a first density and a second density lower than the first density, and is stacked above and below the dense portion 4a. And a rough portion 4b. The rough portion 4b is configured to have a higher opening ratio (opening ratio of the entire mesh) and higher fluidity than the dense portion 4a.

The sodium extraction part 6 of 4th Embodiment is provided in the height corresponding to the dense part 4a.
The second impurity discharge unit 9 is provided above the mesh member 4. The second impurity discharge unit 9 discharges impurities near the liquid surface of the molten sodium A. The second impurity discharge unit 9 includes a pipe 9a connected to the side wall 2a2 of the tank 2 and a valve 9b that opens and closes the flow path of the pipe 9a.

  According to the fourth embodiment having the above-described configuration, the impurity drain (first impurity drain) 5 provided in the bottom 2a1 of the tank 2 and the second impurity provided above the mesh member 4 are further provided. And a discharge unit 9. Most of the impurities sink to the bottom 2a1 of the tank 2 because the specific gravity is heavier than the molten sodium A, but some of the impurities are exceptionally on the liquid surface due to other effects such as the surface tension of the molten sodium A. May float. Therefore, in the fourth embodiment, by providing the second impurity discharge unit 9, impurities are removed above the sodium extraction unit 6. Thereby, it is possible to make it difficult for impurities to flow out of the sodium extraction part 6.

  Further, according to the fourth embodiment, the mesh member 4 includes the dense portion 4a formed at the first density and the rough portion formed at the second density lower than the first density and stacked above and below the dense portion 4a. 4b. For this reason, the lower rough portion 4 b can secure the fluidity of the molten sodium A at the lower portion of the net-like member 4 and can prevent clogging due to impurities sinking to the bottom portion 2 a 1 of the tank 2. Further, the upper rough portion 4b can secure the fluidity of the molten sodium A in the upper part of the mesh member 4 and prevent clogging due to impurities floating on the liquid surface. Moreover, since the sodium extraction part 6 is provided in the height corresponding to the dense part 4a, since impurities can be filtered out by the mesh filter function of the dense part 4a, the outflow of impurities from the sodium extraction part 6 Can be prevented more reliably.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Sodium separation apparatus, 2 ... Tank, 2a1 ... Bottom part, 3 ... Temperature controller, 3A ... 1st temperature adjustment part, 3B ... 2nd temperature adjustment part, 4 ... Reticulated member, 5 ... Impurity discharge part, 6 ... Sodium Extraction unit, 7 ... gas supply device, 8 ... ultrasonic transducer, 9 ... second impurity discharge unit, A ... sodium, S ... accommodation space

Claims (6)

A sodium separator for separating sodium and impurities contained in the sodium,
A tank having a storage space for storing sodium;
A temperature regulator for adjusting the temperature in the accommodation space;
A net-like member provided in the accommodation space,
The tank, possess an impurity discharging portion provided on a bottom portion, and a sodium removal section provided above said impurity discharge unit,
The temperature regulator is
A first temperature adjusting unit that is provided at a height corresponding to the mesh member and adjusts the temperature to the first temperature;
A second temperature adjustment unit that is provided above the mesh member and adjusts the temperature to a second temperature higher than the first temperature;
Sodium separator characterized by the above-mentioned. A sodium separator for separating sodium and impurities contained in the sodium,
A tank having a storage space for storing sodium;
A temperature regulator for adjusting the temperature in the accommodation space;
A net-like member provided in the accommodation space;
An ultrasonic vibrator for applying vibration to the mesh member ,
The tank includes an impurity discharge portion provided at a bottom portion, and a sodium extraction portion provided above the impurity discharge portion.
Sodium separator characterized by the above-mentioned. A sodium separator for separating sodium and impurities contained in the sodium,
A tank having a storage space for storing sodium;
A temperature regulator for adjusting the temperature in the accommodation space;
A net-like member provided in the accommodation space,
The tank has an impurity discharge portion provided at a bottom portion, and a sodium extraction portion provided above the impurity discharge portion,
The mesh member has a dense portion formed at a first density, and a rough portion formed at a second density lower than the first density and stacked above and below the dense portion,
The sodium extraction part is provided at a height corresponding to the dense part,
Sodium separator characterized by the above-mentioned. A sodium separator for separating sodium and impurities contained in the sodium,
A tank having a storage space for storing sodium;
A temperature regulator for adjusting the temperature in the accommodation space;
A net-like member provided in the accommodation space,
The tank includes an impurity discharge portion provided at a bottom portion, a sodium extraction portion provided above the impurity discharge portion, and a second impurity discharge portion provided above the mesh member. ,
Sodium separator characterized by the above-mentioned. The bottom part of the said tank inclines below toward the said impurity discharge part, The sodium separator as described in any one of Claims 1-4 characterized by the above-mentioned. It has a gas supply apparatus which supplies gas to the said accommodation space, The sodium separator as described in any one of Claims 1-5 characterized by the above-mentioned.

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