JP2000005771A - Treating device of silanes-containing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating device of a silanes-containing liquid capable of performing decomposition treatment of the silanes-containing liquid stably for a long period. SOLUTION: In a reactor 1 having a means for allowing the silanes-containing liquid to come into contact with a silanes decomposition liquid, a silanes feed nozzle 3 consisting of a multiple pipe nozzle is provided in the reactor 1, and a feed means of the silanes-containing liquid is constituted by respectively connecting a central port of the multiple pipe nozzle to the silanes-containing liquid feed line 3a and an annular port surrounding the central port to gas feed lines 3b, 3c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silane-containing liquid treating apparatus capable of stably decomposing a silane-containing liquid for a long period of time.

[0002]

2. Description of the Related Art As a waste liquid of silanes generated in a process of producing high-purity silicon, there is a liquid silane containing impurities concentrated in a distillation purification step. These silanes contain silane (SiH ₄ ) and various chlorosilanes, and have a property of reacting with water to produce silicon dioxide (SiO ₂ ).

Conventionally, as a simple method of detoxifying such a silane-containing liquid, a silane-decomposed liquid such as water or an aqueous alkali solution (hereinafter, simply referred to as a decomposed liquid) is contacted in a reaction vessel. It is common to decompose. For example, a method has been proposed in which a silane-containing solution is brought into contact with water to decompose a part of the solution, and then brought into contact with an aqueous alkali solution (Japanese Patent Application Laid-Open No. H4-124011).

In the above-mentioned contact, a reaction vessel provided with a nozzle for supplying a silane-containing liquid and a decomposition liquid so as to open inside thereof is generally used.

However, since these silane-containing liquids react with moisture to produce solid silicon dioxide (SiO ₂ ), the inside of the nozzle for supplying the silane-containing liquid to the reaction vessel or in the vicinity of the tip thereof is used. Is often clogged by such silicon dioxide and the process must be interrupted and an open wash performed. The time to such an occlusion is
Although it depends on the structure of the container, the processing method, the processing speed, and the like, it takes several days or even several hours, which is a very serious problem in performing industrially continuous processing.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for treating a silane-containing liquid for decomposing a silane-containing liquid, wherein a nozzle for supplying the silane-containing liquid is blocked by silicon dioxide. It is an object of the present invention to provide an apparatus which can prevent the silanes-containing liquid from being continuously decomposed industrially advantageously.

[0007]

Means for Solving the Problems The present inventors have a structure for preventing the inside or near the tip of a nozzle for supplying a liquid containing silanes to a reaction vessel used for a decomposition reaction from being blocked by silicon dioxide. As a result of intensive studies, a multi-tube nozzle is adopted as a nozzle for supplying a silane-containing liquid, and a silane-containing liquid is supplied from a central port of the multi-tube nozzle, and a gas is supplied from an annular port surrounding the central port. By configuring the means for supplying the silane-containing liquid,
The inventors have found that the phenomenon that the nozzle for supplying the silane-containing liquid is blocked by silicon dioxide generated in the reactor can be prevented very effectively, and have completed the present invention.

That is, the present invention provides a reaction vessel for bringing a silane-containing liquid into contact with a silane-decomposed liquid, wherein a multi-tube nozzle is provided in the reaction vessel as a means for supplying the silane-containing liquid. And a silane-containing liquid supply line connected to a central port of the multi-tube nozzle and a gas supply line connected to an annular port surrounding the central port.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, silane-containing liquids include monochlorosilane (SiH ₃ Cl), dichlorosilane (SiH ₂ Cl ₂ ), and trichlorosilane (SiHC).
l ₃ ), silicon tetrachloride (SiCl ₄ ), and liquids containing polychlorosilanes (chlorosilanes having one or more Si—Si bonds) alone or as a mixture. Specifically, starting with liquid silanes such as silicon tetrachloride, etc., liquid silanes are dissolved or suspended in the liquid silanes, and silanes are dissolved or suspended in a solvent such as kerosene. A liquid material.

In the present invention, the decomposition solution is not particularly limited as long as it can decompose the silane by contact with the above silanes, and a known decomposition solution is used without any limitation.
For example, water or an alkaline solution such as an aqueous sodium hydroxide solution or lime milk is generally used.

FIG. 1 is a schematic diagram showing a typical embodiment of the processing apparatus of the present invention.

In the present invention, the reaction vessel 1 is for bringing the silane-containing liquid into contact with the decomposition liquid.
At least a means for supplying a silane containing liquid is provided. That is,
A means for supplying the decomposition solution is not particularly provided, and it is also possible to use a large amount of the decomposition solution in the reaction vessel so as to contact the reaction solution in batches.

However, industrially, in such a reaction vessel,
It is desirable to provide a supply means for the decomposition solution together with the supply means for the silanes.

In the above embodiment, as shown in FIG. 1, the provision of the mixing zone 2 in which the silane-containing liquid and the silane-decomposing liquid are forcibly brought into contact in the reaction vessel 1 makes the decomposition reaction efficient. Recommended for doing well. in this case,
Generally, a means for supplying a silane-containing liquid and a silane-decomposed liquid is provided on the inlet side to the mixing zone.

In FIG. 1, the respective liquids are supplied from outside to a reaction vessel 1 where they are brought into contact. Examples of the mode of forming the mixing zone 2 include a mode in which a packing layer containing a commercially available contact filler such as terraret is provided, and a mode in which a static mixing device called a static mixer is provided. And the like.

Among them, an embodiment using a static mixer is preferable because the silane-containing liquid and the silane-decomposed liquid can be mixed with good reactivity. When the above static mixer is used, it is necessary to pass a silane-containing liquid and a silane-decomposed liquid together with a gas through the mixer, and the liquid (kg) / gas (m ³ ) ratio is 50 to 500.
0 kg / m ³ is appropriate.

In the above reaction, in the conventional apparatus, silicon dioxide was generated by contact of the silane with water at the opening of the nozzle for supplying the silane. Then, once the generated silicon dioxide adheres to the tip of the nozzle, the portion triggers the silicon dioxide to rapidly expand, eventually leading to nozzle blockage.

In the present invention, in order to prevent such blockage, a multi-tube nozzle 3 is provided in the reaction vessel 1 with an opening, and a silane-containing liquid supply line 3a is provided at the center of the multi-tube nozzle. Gas supply line 3 at the annular port surrounding the
It is very important that b and, if necessary, 3c be connected to form a supply means for the silane-containing liquid.

That is, a silane supply nozzle member is formed by using a multi-pipe configured to supply gas to an annular port surrounding a central port for supplying a silane-containing liquid and forming a gas curtain around the central port. It is possible to prevent silanes and moisture from contacting the surface, and even if contact occurs, it is possible to forcibly remove generated silicon dioxide, and to supply the silane-containing liquid supply nozzle for a long time. Blockage can be effectively prevented.

As the gas to be supplied to the annular port, air or nitrogen is preferably used. Since this gas comes into contact with silanes released from the central nozzle, water is sufficiently removed, generally 10 ppm or less. It is desirable that

The annular port surrounding the central port from which the silanes are released may be single, but by providing two or more, the adhesion of silicon dioxide can be more effectively prevented.

It is desirable that the gas blown from the annular port surrounding the multi-tube has a blowing linear velocity of at least 1 m / s, preferably at least 2 m / s. It is preferable that the blowing linear velocity be faster as it is more effective in isolating silanes and water. This isolation effect is affected not by the absolute amount of gas to be supplied but by the linear velocity of the gas blown out. Therefore, if the gap between the gas nozzles is narrowed, the adhesion of silicon dioxide can be effectively prevented with a small amount of gas. At this time, if gas is ejected at a high linear velocity from the gap between the narrow gas nozzles, the liquid silanes supplied from the central silane nozzle are dispersed in a mist form after being discharged from the nozzle, so that the silanes are effective. There are additional advantages, such as decomposition into.

The silicon dioxide that closes the nozzle usually starts to adhere from the tip of the nozzle. That is, when the gas flow separates from the nozzle wall at the tip of the nozzle, a gas vortex is formed, and the vortex of silanes and the water filling the inside of the reactor are simultaneously caught in the vortex and react with each other. This is because silicon dioxide adheres to the nozzle wall surface. Separation of a gas flow from a wall that forms a gas vortex is likely to occur when the shape of the wall changes rapidly.

Therefore, in the processing apparatus according to the present invention, FIG.
As shown in (1), adopting a mode in which the thickness of the wall defining the multi-tube nozzle is gradually reduced toward the tip thereof increases the effect of preventing adhesion of silicon dioxide at the nozzle tip. This is preferable. Most preferably,
In this embodiment, the tip is sharpened like a blade.

As described above, it is possible to process the tip of the wall constituting the multi-tube nozzle so as to gradually reduce the wall thickness by using the central port 3-1 for supplying the silane-containing liquid and the annular port 3 surrounding the central port 3-1. -2 is particularly important in the wall that separates the annular port 3-2, but is also effective in the wall outside the annular port 3-2.

Although the use of the multi-tube nozzle as described above prevents silicon dioxide from adhering at the nozzle tip, depending on the size and shape of the reaction vessel, the dioxide may be spread around the outermost nozzle of the multi-tube nozzle. Silicon may adhere and enlarge. When the inner diameter of the decomposition reaction vessel is relatively small, as shown in FIG.
By adopting a mode in which the outer wall constituting -2 is constituted by the inner wall of the reaction vessel, the outer peripheral portion of the multi-tube nozzle to which silicon dioxide adheres can be essentially eliminated, which is preferable.

On the other hand, the above-described embodiment can be adopted even when the inner diameter of the decomposition reaction vessel is large. However, an enormous amount of gas is required in order to obtain a nozzle blowing linear velocity of 1 m / s or more. This is often not desirable. In such a case, a thin multi-tube nozzle is inserted into the wide decomposition vessel. At this time, the outer periphery of the multi-tube nozzle is exposed to the vapor and moisture of silanes filling the inside of the reactor. At the same time, they are exposed to the opportunity to come into contact with one another, and silicon dioxide may adhere and become enlarged.

In order to prevent such a phenomenon, it is preferable to provide a liquid supply means 8 for forming a liquid layer having a flow at the outer periphery of the multi-tube nozzle for supplying the silane-containing liquid.
As the silane decomposition solution used here, water or an aqueous alkali solution is suitably used. As a method for forming a liquid layer having a flow, a mechanism for supplying the silane decomposition solution so that the decomposition solution comes into contact with the outer peripheral portion of the multi-tube nozzle is used without any particular limitation. The method of contacting the silane decomposition solution with the outer peripheral portion of the multi-tube nozzle may be carried out by using a general spray nozzle or a simple tube nozzle, and may be discharged toward the multi-tube nozzle. The structure of the outer peripheral portion of the reaction vessel or the multi-tube nozzle may be such that the decomposition solution supplied in the step (1) comes into contact with the multi-tube nozzle through members such as the reaction vessel.

Similarly, also in the gas phase portion of the reaction vessel, in order to prevent the silicon dioxide from adhering, liquid supply means 9, 10 for forming a liquid layer having a flow on the inner wall of the reaction vessel. Is desirably provided. As the silane decomposition solution used here, water or an aqueous alkali solution is suitably used, as described above.

As a method for forming a liquid layer having a flow, a mechanism capable of supplying a silane decomposition solution to the inner wall of the reaction vessel is employed without any particular limitation.

For example, FIG. 1 shows an embodiment in which a part of the decomposition solution is supplied from nozzles 8, 9 and 10 for forming a liquid layer as an embodiment in which a liquid layer having a flow on the inner wall of the reaction vessel is formed.

In the treatment apparatus of the present invention, the method of supplying the silane decomposition liquid is not particularly limited, but generally, the silane decomposition liquid is continuously supplied from the decomposition liquid supply nozzles 11 and 12 as shown in FIG. It is. Of course, it is also possible to incorporate it in the reaction vessel in advance if necessary.

Further, if the description is continued with reference to FIG. 1, the decomposed liquid after the contact is partly withdrawn from the lower part of the reaction vessel 1 by a line 13, and the other part by a pump 6 through a cooler 7 and a pH meter. Control valve 5 according to the detected pH
Thus, the supply amount of the decomposition liquid from the decomposition liquid supply line 4 is controlled.

[0034]

As can be understood from the above description, according to the processing apparatus of the present invention, a gas curtain is formed around a supply port for supplying a silane-containing liquid to a reaction vessel using a multi-tube nozzle. Therefore, the water filling the reaction vessel can be isolated from the silanes present at the tip of the silane supply nozzle, and silicon dioxide can be prevented from forming and adhering at the tip of the nozzle.

Therefore, it is possible to prevent the supply nozzle from being clogged by silicon dioxide during the process of decomposing the liquid waste supplied as the silane-containing liquid, and to achieve industrially stable continuous operation. It has become possible to continue the treatment reaction.

[0036]

EXAMPLES The present invention will be described specifically with reference to Examples and Comparative Examples below, but the present invention is not limited to these Examples.

Example 1 A waste liquid containing silanes was treated using an apparatus as shown in FIG. In this apparatus, the straight body of the treatment reaction tower 1 has an inner diameter of 125 mm and a length of 3 m, and a 1-inch teralet as a filler 2 is about 2 m below the straight body.
Filled with height. The upper part of the treatment tower has a conical shape with a top angle of about 60 degrees, and a silane supply nozzle 3 for supplying a silane waste liquid was inserted from the center of the tip of the cone.

The silane supply nozzle 3 is a triple tube nozzle, supplies silane liquid from a central port 3-1 through a line 3a, and lines 3b, 3c from an annular port surrounding the periphery thereof. Respectively, and nitrogen was supplied.

The outer diameter of each nozzle of the triple tube nozzle was 8 mm, 12 mm, and 21.7 mm from the center nozzle, respectively.
And the wall pressure of each nozzle was 1 mm, 1 mm, and 3.7 mm, respectively. In the vicinity of the tip of each nozzle, a material whose thickness was gradually reduced on the outside over a length of 10 mm to 50 mm was used so that the wall pressure at the tip became 0.5 mm or less.

The decomposition solution is replenished from the decomposition solution supply port 4 with an aqueous solution of about 10% by weight of sodium hydroxide. The replenishing amount is controlled by the control valve 5 so that the pH of the treatment reaction solution is maintained at 12 to 14. Adjusted. On the other hand, a part of the processing liquid was discharged from the line 13 located at the lower part of the processing tower due to the overflow and the gas generated by the decomposition reaction together.

The decomposition solution is supplied by the circulation pump 6 from the supply nozzle 8 near the top of the cone at the top of the processing tower at a flow rate of about 1 m ³ / H, and the nozzles 9 and 10 near the boundary between the straight body and the cone.
Total flow rate of about 3m ³ / H, and the processing tower O supplied from the spray nozzle 11 and 12 located under approximately 50cm from the top inside treatment tower at a rate of a total of about 2m ³ / H of the straight body portion from the circulation did. At this time, the decomposition liquid was supplied from the nozzle 8 and the nozzles 9 and 10 in the tangential direction inside the reaction vessel so that a liquid layer having a uniform flow was formed inside the conical portion and the cylindrical portion. With respect to 8, the decomposition solution was arranged so that a part of the decomposition solution was in contact with the triple tube nozzle 3. Since the decomposition reaction is an exothermic reaction, the circulating liquid is supplied to the cooler 7.
To prevent overheating.

The composition of the waste liquid to be treated is about 65% by weight of silicon tetrachloride, about 33% by weight of chlorodisilanes such as disilicon hexachloride (Si ₂ Cl ₆ ), and other high boiling polychlorosilanes. Was about 2% by weight. About 3
The treatment was carried out by supplying from the central port of the triple tube nozzle at a flow rate of 0 L / H, and supplying nitrogen at a flow rate of 1 Nm ³ / H from the annular port of the triple tube respectively.

When the silane waste liquid was treated under the above conditions, the silicon oxide solid discharged from the line 13 had an average particle size of 2 mm or more, and unreacted silane remained inside. The gas discharged from the line was very odorous acidic white smoke, and the concentration of hydrochloric acid was 1000 ppm or more. However, the processing was continued because no device-related trouble was recognized. 30
After the treatment was performed for consecutive days, the apparatus was stopped and the inside was inspected. However, almost no deposition of silicon dioxide or the like was observed inside the treatment tower, and the condition was the same as before the start of the treatment.

Comparative Example 1 The same apparatus as that used in Example 1 was used, and a single tube nozzle having an outer diameter of 8 mm and a wall pressure of 1 mm was used instead of the triple tube nozzle 3. Further, care was taken to prevent the decomposition liquid supplied from the nozzle from directly contacting the tube nozzle. Other conditions were the same as in Example 1, and the treatment of the silane waste liquid was started. When about 12 hours had passed, a large amount of silicon dioxide was deposited at the tip of the silane supply nozzle to supply the silane. It became impossible to continue the processing operation.

Example 2 A commercially available static mixer element having a helical blade that divides the flow path into two equal parts and rotates 180 degrees was mounted in place of the filled teralet in the apparatus shown in FIG. Each element was filled with a total of 15 elements while the flow path was further divided into two equal parts to the element at the preceding stage, and arranged sequentially so that the turning direction was reversed. Other conditions were the same as in Example 1.

As a result, inside this element, the mixture of the decomposition solution and the silane solution is vigorously stirred by gravity and the pressure difference energy of nitrogen, and the silicon oxide solid discharged from the line 13 has an average particle diameter of 1 mm or less. Becomes
Substantially no unreacted silanes were found inside. The concentration of hydrochloric acid in the gas discharged from the line was 2 ppm or less, and the gas was substantially colorless and odorless. After performing the treatment for 30 consecutive days while maintaining this state, the apparatus was stopped and the inside was inspected. However, deposition of silicon dioxide or the like was hardly observed in the inside of the treatment tower. It was a similar situation.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a typical embodiment of a silane-containing liquid treatment apparatus of the present invention.

FIG. 2 is a schematic view showing one embodiment of a means for supplying a silane-containing liquid in the present invention.

FIG. 3 is a schematic view showing another embodiment of the supply means of the silane-containing liquid in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Packing 3 Silane supply nozzle 4 Decomposition liquid supply port 8-10 Nozzle for forming a liquid layer 11, 12 Decomposition liquid supply nozzle

Claims (5)

[Claims] 1. A reaction vessel for contacting a silane-containing liquid and a silane-decomposed liquid, wherein a multi-tube nozzle is provided in the reaction vessel as a supply means for supplying the silane-containing liquid, the multi-tube nozzle being provided. A silane-containing liquid processing apparatus, wherein a silane-containing liquid supply line is connected to a central port of a nozzle, and a gas supply line is connected to an annular port surrounding the central port. 2. An annular port surrounding the central port is provided in two or more layers,
2. The apparatus for treating a silane-containing liquid according to claim 1, wherein a gas can be supplied from each of the annular ports. 3. The apparatus for treating a silane-containing liquid according to claim 1, wherein the wall defining the central port and the annular port is configured such that the wall thickness decreases toward the tip. 4. A reaction vessel is provided with a mixing area for forcibly bringing the silane-containing liquid and the silane-decomposing liquid into contact with each other, and the silane-containing liquid and the silane-decomposing liquid are provided on the inlet side to the mixing area. The apparatus for treating a silane-containing liquid according to claim 1, further comprising a supply unit. 5. The apparatus for treating a silane-containing liquid according to claim 4, wherein the mixing zone is constituted by a static mixer.