JP2014040345A - Method for sealing gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sealing a gas, which maintains airtightness to a high degree at the fitting part between the insertion part and the support part of a segmented reaction vessel for use in manufacturing device of a polycrystalline silicon.SOLUTION: The method for sealing a gas at the fitting part between the insertion part and the support part of a segmented reaction vessel for use in manufacturing device of a polycrystalline silicon includes at least the step of arranging a string-like gas sealing material in a groove formed at the fitting part. The gas sealing material is formed by treating a metal wire reinforced braid of ceramic fiber with inorganic filler and/or organic filler.

Description

  The present invention relates to a gas sealing method for a split reactor used in a polycrystalline silicon production apparatus.

  Silicon wafers for solar cells are manufactured by silicon ingots obtained by the Siemens method, zinc reduction method, etc., as well as crucible residue after pulling up single crystal silicon for semiconductors, cutting chips of single crystal silicon ingots, etc. It is manufactured from a silicon ingot obtained by melting scraps, removing impurities, cooling and crystallizing.

  Patent Documents 1 and 2 include a silica glass gas supply nozzle made of quartz glass inserted downward from above, a reducing agent gas supply nozzle and an exhaust gas extraction pipe, and a heating means on the outer peripheral surface. A manufacturing method and a manufacturing apparatus are described in which high purity polycrystalline silicon is aggregated and grown in a tubular shape at the tip of a silicon chloride gas supply nozzle using a reactor. The high-purity polycrystalline silicon obtained by the production methods disclosed in these patent documents can be easily crushed because it has an aggregated shape in a tubular shape, and can be obtained as a needle shape or a dendritic shape by crushing. . Such high-purity polycrystalline silicon can be used, for example, as it is for pulling a single crystal ingot by the CZ method or as a raw material for a polycrystalline silicon ingot. In addition, it is useful for filling gaps in bulk silicon during the production of polycrystalline silicon ingots.

JP 2007-145663 A JP 2007-223822 A

  By the way, the reactor used at the time of manufacture of the high purity polycrystalline silicon disclosed in Patent Documents 1 and 2 is a so-called split reactor composed of an insertion portion and a support portion, and this split reactor is Since the insertion portion and the support portion are fitted together, it is necessary to maintain a high degree of airtightness of the fitting portion between the insertion portion and the support portion, and an advanced gas sealing method is required.

  The present invention has been made in view of such circumstances, and highly maintains the airtightness of the fitting portion between the insertion portion and the support portion in the split reactor used in the polycrystalline silicon manufacturing apparatus. It is an object of the present invention to provide a gas sealing method capable of performing the above.

  A braided ceramic fiber reinforced with metal wire, treated with an inorganic filler and / or organic filler, and formed into a string is packed into the gap between the insertion part and the support part. By using it as a gas seal material, the above problem can be solved.

  According to the present invention, the insertion portion of the split reactor is formed by using a gas seal material formed by processing a braid of ceramic fibers reinforced with a metal wire with an inorganic filler and / or an organic filler into a string shape. Since the gas seal of the fitting portion with the support portion is performed, the airtightness of the fitting portion can be maintained at a high level.

  In addition, since the gas seal material is fastened and fixed with a predetermined tightening torque via the presser fitting, the tightness of the fitting portion can be maintained at a high level.

It is a schematic sectional drawing of the split reactor used for the polycrystalline silicon manufacturing apparatus which employ | adopted the gas sealing method of this invention. FIG. 2 is a schematic enlarged cross-sectional view of a fitting portion between an insertion portion and a support portion in the split reactor shown in FIG. 1. It is a schematic sectional drawing of the airtight test apparatus which consists of the same material as the split reactor shown in FIG. 1, and has the same structure. It is a schematic perspective view of the gas seal material used for the polycrystalline silicon manufacturing apparatus which employ | adopted the gas seal method of this invention, Fig.4 (a) demonstrates the state which formed the end-string-like gas seal material in the ring shape FIG. 4B is a schematic perspective view for explaining a state in which gas seal materials formed in a ring shape are stacked.

The present invention has the following configuration.
[1]
A gas sealing method of a fitting portion between an insertion portion and a support portion of a split reactor used in a polycrystalline silicon manufacturing apparatus, wherein a ceramic reinforced with a metal wire in a groove formed in the fitting portion A gas sealing method comprising at least a step of disposing a gas sealing material formed into a string by treating a braid of fibers with an inorganic filler and / or an organic filler.
If such a gas seal material is used to perform gas sealing at the fitting portion between the insertion portion and the support portion of the split reactor, high airtightness can be obtained, contributing to the production of high-purity polycrystalline silicon. can do.

[2]
After the step of disposing the gas seal material, the press fitting is clamped and fixed to the support portion with a tightening torque of 100 to 200 N · m via a fastening member in a state where the press fitting is pressed against the gas seal material. The gas sealing method according to [1], including a step of:
In this way, high airtightness can be obtained by fixing the pressing metal with a predetermined tightening torque.

[3]
The gas sealing method according to [2], including a step of raising the temperature of the split reactor to 800 to 1200 ° C after the step of fastening and fixing.
[4]
The gas sealing method according to [3], further including a step of further tightening and fixing the presser fitting to the support portion with a tightening torque of 100 to 200 N · m after the step of raising the temperature.
If tightening is performed in this manner, higher airtightness can be obtained.

[5]
The gas seal according to any one of [1] to [4], wherein when the holding pressure in the split reactor is 0.5 kPa, a leak amount from the fitting portion is 5 L / hr or less. Method.
Thus, since it can be suppressed to a slight leak amount, high-purity polycrystalline silicon can be reliably manufactured.

[6]
The gas sealing method according to any one of [1] to [5], including a step of cooling a flange portion of the support portion to which the pressing metal fitting and the fastening member are fixed using a cooling means.
If the flange portion to which the presser fitting and the fastening portion are fixed is cooled in this way, even if the presser fitting is exposed to a high temperature, deterioration and deformation do not occur, and high airtightness can be maintained over a long period of time.

Hereinafter, embodiments of the gas sealing method of the present invention will be described in more detail based on the drawings.
<Split reactor>
FIG. 1 is a schematic cross-sectional view of a split reactor used in a polycrystalline silicon manufacturing apparatus employing the gas sealing method of the present invention, and FIG. 2 shows an insertion section and a support section in the split reactor shown in FIG. It is a schematic cross-sectional enlarged view of the fitting part. The split reactor C employing the gas sealing method of the present invention is roughly composed of an insertion part A and a support part B as shown in FIG. 1 and FIG. Is provided. The insertion portion A of the split reactor C is formed in a cylindrical shape, and a reducing agent gas supply nozzle 1 and a silicon chloride gas supply nozzle 2 made of, for example, quartz glass are provided so as to penetrate the top surface. Yes. Further, the insertion portion A is provided with a heater 8 so as to surround the periphery thereof, and a heat insulating material 10 is provided outside the heater 8.

  The material of the heat insulating material 10 is preferably a molded body mainly composed of spherical fumed silica, or a molded body composed of amorphous silica, a metal oxide, a glass filament, and the like, and further, a silica-based or alumina-silica blanket. Or cross-shaped. Such a heat insulating material 10 is thin and lightweight, and can suppress the heat radiation of the material in contact therewith. A cylindrical casing 18 covers the outside of the heat insulating material 10.

  On the other hand, the support part B has a bottomed cylindrical shape, and its outline is formed of a castable (refractory material) 11, and the exhaust gas extraction pipe 3 extends from the inside to the outside of the castable (refractory material) 11. Further, a bottom plate 7 is provided on the bottom surface, and a jacket 18 is provided so as to cover the periphery of the castable (refractory material) 11. The castable (refractory material) 11 is provided with a cylindrical stepped portion 19 on the inner side. When the insertion portion A is fitted to the support portion B, the lower end of the insertion portion A is the step of the support portion B. It comes into contact with the attachment 19. At this time, a gap is formed in the fitting portion 20 between the insertion portion A and the support portion B, and this gap serves as a groove 21 for loading the gas seal material 4.

  Further, the flange 9 on the upper surface of the end portion of the stepped portion 19 is provided with a pressing metal 5 and a fastening member 6 for holding the gas seal material 4 loaded in the groove 21, and the pressing metal 5 attaches the fastening member 6 to the flange 19. Thus, the flange portion 9 is fastened and fixed. For example, iron can be used as the material of the presser fitting 5, the fastening member 6, and the flange portion 9. However, in order to prevent deterioration and deformation at high temperatures, cooling can be performed using a cooling means (not shown). preferable. As a cooling means (not shown), for example, a method of cooling the inside of the presser fitting 5 and the flange portion 9 through a coolant can be cited. Then, after the gas seal material 4 is loaded into the groove 21, the presser fitting 5 is applied to the gas sealant 4, the presser fitting 5 is fastened and fixed by the fastening member 6, and the insertion portion A is fitted to the support portion B. By combining them, a gas seal in the split reactor C is made.

  The gas sealing material 4 loaded in the groove 21 is not limited to one, and may be loaded, for example, vertically in a plurality. Further, the gas seal material 4 may be a ring shape or an end string shape. When the end-striped gas seal material 4 is used, when the end-strip-like gas seal material 4 is stacked and loaded in the groove 21, the position of the end of each gas seal material 4 is the same. What is necessary is just to arrange | position so that it may not become a position.

  Also, the cross-sectional shape of the gas seal material 4 is not particularly limited. However, if the cross-sectional shape is a square shape, the gas seal material 4 can be loaded into the groove 21 without any gap when stacked, which is preferable. Here, the material of the insertion part A and the support part B is, for example, selected from silica, quartz, silicon carbide, silicon nitride, alumina, zirconia, a combination thereof and / or a mixture thereof and a castable (refractory material) However, from the viewpoint of the quality of the silicon product, it is more preferable that the main component is fused silica, quartz, silicon carbide, or silicon nitride. Further, the gas seal material 4 loaded in a groove 21 (for example, about φ900 mm) formed in the fitting portion 20 between the insertion portion A and the support portion B braids ceramic fibers reinforced with a metal wire, and flows this In order to improve the property and elasticity, it is preferable to use a material formed by processing with an inorganic filler and / or an organic filler into a string having a square cross section.

  Here, as the material of the metal wire, for example, stainless steel, inconel, titanium alloy, nickel alloy, copper alloy, aluminum alloy or the like can be used. Furthermore, as a material of the ceramic fiber, for example, alumina, zirconia, silicon carbide, silicon nitride, silicon oxide, or the like can be used. As the material for the inorganic filler, for example, mica, clay, silica, wollastonite, talc, vermiculite, steatite, molybdenum disulfide and the like can be used. Furthermore, as the material of the organic filler, for example, organic fibers such as aramid, polyester, urea, phenol, and fluororesin, carbon and / or rubber can be used.

  In such a split reactor C, the inside is heated by the heater 8 during the reaction, and the heat insulating material 10 prevents the reaction temperature from decreasing. Further, the shape of the lower end of the insertion portion A inserted into the support portion B is preferably cylindrical in order to alleviate the partial stress accompanying the loading of the gas seal material 4. If the gas seal of the fitting part 20 between the insertion part A and the support part B of the split reactor C is performed using such a gas seal material 4, high airtightness can be obtained, and high-purity polycrystalline It can contribute to the production of silicon.

Hereinafter, a gas sealing method of the fitting portion 20 between the insertion portion A and the support portion B of the split reactor C configured as described above will be described.
<Gas sealing method>
First, the gas seal material 4 described above is loaded into the gas seal groove 21 of the fitting portion 20 between the insertion portion A and the support portion B at the outside air temperature, and the presser fitting 5 is attached to the gas seal material 4 in this state. This is clamped and fixed by the fastening member 6 with a fastening torque of 100 to 200 N · m, and then the temperature is raised. The tightening torque is preferably 130 to 170 N · m, more preferably 140 to 160 N · m. Then, after the temperature inside the split reactor C is raised to 800 to 1200 ° C., the fastening member 6 is further tightened with a tightening torque of 100 to 200 N · m. Thereby, favorable airtightness can be obtained.

  The temperature rising temperature inside the split reactor C is preferably 900 to 1100 ° C., and the tightening torque for retightening is preferably 130 to 170 N · m, more preferably 140 to 160 N · m. Thus, by tightening the fastening member 6 with a predetermined torque after the temperature rise, the airtightness for a long time at the time of the temperature rise can be maintained, and this airtightness can be maintained even after cooling. . Such airtightness is not retained when the reactor is once cooled and then heated again. Therefore, when the split reactor C is heated again, the fastening member 6 is tightened again (increase tightening) after the temperature rises. Therefore, high airtightness can be maintained.

  The airtight test apparatus D shown in FIG. 3 is composed of members of the same type and the same material as the split reactor C of FIGS. 1 and 2. In this embodiment, the airtight test apparatus D is divided into The environment of the reactor C was reproduced, and the airtightness was measured.

  The basic structure of the airtight test apparatus D is basically the same as the structure in the split reactor C shown in FIGS. 1 and 2, and therefore the same constituent members are denoted by the same reference numerals and the details thereof are described. The detailed explanation is omitted.

In the figure, reference numeral 12 is a fastening member for fixing the jacket, 13 is a ceramic board heat insulating material, 14 is a thermometer, 15 is an internal heater, 16 is a nitrogen gas inlet, and 17 is a nitrogen gas outlet. Further, the thermometer 14, the internal heater 15, the nitrogen gas outlet 17 and the like are provided with a closing flange, an adjustment valve (not shown) and the like in order to keep the air tightness in the air tightness test apparatus.
Here, as the material for the protective tube of the thermometer 14 and the protective tube of the internal heater 15, for example, a ceramic material mainly composed of silicon nitride or alumina is employed.

[Example 1]
Using an insertion part A made of a quartz crucible of φ900 mm, the insertion part A is set on a stepped portion 19 of a support part B made of a castable (refractory material) 11 mainly composed of silicon carbide at an outside temperature, A 25 mm square gas seal material 4 cut to the length of the inner diameter of the groove 21 (packing made by Nippon Valqua Industries, Ltd.) in a groove 21 having a width of 25 mm formed in the fitting part 20 of the insertion part A and the support part B # N340) is loaded in the form of a ring and the cut end is shifted by 120 degrees and stacked in eight stages, and the presser fitting 5 having 32 bolt holes is put on the gas seal material 4 and the fastening member 6 is tightened with a tightening torque of 150 N · m. The airtight test device D having the structure shown in FIG. 3 was obtained by passing water at room temperature through a cooling pipe (not shown) provided inside the presser fitting 5 and the flange portion 9 of the support portion B. At this time, in order to make the internal pressure in the airtight test apparatus D the same as the internal pressure of the split reactor C shown in FIG. 1, nitrogen gas is introduced from the nitrogen gas inlet 16 and a control valve is connected to the nitrogen gas outlet 17. The holding pressure was set to 0.5 kPa. In this state, the airtightness test apparatus D is heated so that the internal temperature becomes 1000 ° C., and the fastening member 6 is further tightened at this temperature with a tightening torque of 150 N · m. Was 59%.
The leak amount of nitrogen gas immediately after retightening of the fastening member 6 is very small at 2 L / hr under a holding pressure of 0.5 kPa, and the temperature in the airtight test device D is kept at 1000 ° C., and after 50 hours. The amount of nitrogen gas leaked was 2 L / hr.

[Example 2]
In Example 1, in the airtight test apparatus D in which the temperature in the airtight test apparatus D was maintained at 1000 ° C. and the leak amount of nitrogen gas was 2 L / hr under a holding pressure of 0.5 kPa even after 50 hours. The temperature in D was lowered from 1000 ° C. to the outside air temperature. At this time, the leakage amount of nitrogen gas was 5 L / hr under a holding pressure of 0.5 kPa. When the temperature inside the hermetic test apparatus D was raised to 1000 ° C. again, the nitrogen gas leak amount was 39 L / hr under a holding pressure of 0.5 kPa.

  Here, the fastening member 6 was further tightened with a torque of 150 N · m, and the contraction degree of the gas seal material 4 was set to 57%. At this time, the leakage amount of nitrogen gas under a holding pressure of 0.5 kPa is 3 L / hr, the temperature in the airtight test apparatus D is maintained at 1000 ° C., and the leakage amount after 24 hours is under a holding pressure of 0.5 kPa. It was very slight at 1 L / hr.

[Example 3]
Using an insertion part A made of a quartz crucible of φ900 mm, the insertion part A is set on a stepped portion 19 of a support part B made of a castable (refractory material) 11 mainly composed of silicon carbide at an outside temperature, Cut into the length of the inner diameter of the groove 21 as shown in FIGS. 4A and 4B in the groove 21 having a width of 25 mm formed in the fitting portion 20 of the insertion portion A and the support portion B. The formed 25 mm square end-string-like gas seal material 4 (packing # N340 manufactured by Nippon Valqua Industries, Ltd.) in a ring shape was loaded in six layers.

In addition, when loading in 6-stage stacking, the positions (cut ends 4a) where both ends of the gas seal material 4 formed in a substantially ring shape face each other were shifted by 120 degrees.
After the loading, the gas seal member 4 is covered with a pressing metal fitting 5 having 32 bolt holes, and the fastening member 6 is fastened and fixed with a fastening torque of 150 N · m. did. At this time, in order to make the internal pressure in the airtight test apparatus D the same as the internal pressure of the split reactor C shown in FIG. 1, nitrogen gas is introduced from the nitrogen gas inlet 16 and a control valve is connected to the nitrogen gas outlet 17. The holding pressure was set to 0.5 kPa. Further, the temperature in the airtightness test apparatus D was increased to 1000 ° C., and further tightened with a fastening member 6 with a torque of 150 N · m, so that the contraction degree of the gas seal material 4 was 50%. The amount of nitrogen gas leaked immediately after the fastening member 6 was tightened was 3 L / hr under a holding pressure of 0.5 kPa.

  At this series of outside air temperature, the holding metal fitting 5 is fastened and fixed with a tightening torque of 150 N · m, and further tightened with a tightening torque of 150 N · m at a temperature of 1000 ° C. in the airtightness test apparatus D, and lowered to the outside temperature 1 Cycle. By repeating this operation, the leakage amount of nitrogen gas immediately after bolting at 150 N · m at 1000 ° C. in the fourth cycle is 2 L / hr under a holding pressure of 0.5 kPa, and the shrinkage of the gas seal material 4 is 44%. Further, the leakage amount of nitrogen gas immediately after fastening of the fastening member 6 at 150 N · m at 1000 ° C. in the seventh cycle is 3 L / hr under a holding pressure of 0.5 kPa, and the shrinkage of the gas seal material 4 is 42%. Met. Further, the leak amount of nitrogen gas immediately after fastening of the fastening member 6 at 150 N · m at 1000 ° C. in the 10th cycle is 4 L / hr under a holding pressure of 0.5 kPa, and the contraction degree of the gas seal material 4 is 42%.

Furthermore, the temperature in the airtightness test apparatus D was kept at 1000 ° C., and the amount of nitrogen gas leaked after 46 hours was very small at 4 L / hr under a holding pressure of 0.5 kPa.
From the results of Examples 1 to 3, it was confirmed that the gas sealing method of the present invention was effective as a gas sealing method for a split reactor for producing high-purity silicon using a zinc reduction method.

[Comparative Example 1]
Using an insertion part A made of a quartz crucible of φ900 mm, the insertion part A is set on a stepped portion 19 of a support part B made of a castable (refractory material) 11 mainly composed of silicon carbide at an outside temperature, A 25 mm square gas seal material 4 cut to the length of the inner diameter of the groove 21 (packing made by Nippon Valqua Industries, Ltd.) in a groove 21 having a width of 25 mm formed in the fitting part 20 of the insertion part A and the support part B # N340) is loaded in the form of a ring and the cut end is shifted by 120 degrees and stacked in eight stages, and the presser fitting 5 having 32 bolt holes is put on the gas seal material 4 and the fastening member 6 is tightened with a tightening torque of 150 N · m. Was tightened and fixed to obtain an air tightness test apparatus D having the structure shown in FIG.

  At this time, the degree of contraction of the gas seal material 4 is 63%, and in order to make the internal pressure in the airtight test apparatus D the same as the internal pressure of the split reactor C shown in FIG. Gas was introduced and a regulating valve was attached to the nitrogen gas outlet 17 to set the holding pressure to 0.5 kPa, but the nitrogen gas leakage immediately after tightening by the fastening member was 2 L / hr.

However, when the temperature in the airtightness test apparatus D was further increased to 1000 ° C. by further heating, the amount of nitrogen gas leaked was as large as 54 L / hr.
From this result, if the zinc reduction reaction is performed only by fastening the fastening member 6 before the temperature rise (at the outside temperature) without performing the tightening after the temperature rise, the amount of leakage of the source gas, the reaction gas, etc. is large. It is easily estimated that

DESCRIPTION OF SYMBOLS A ... Insertion part B ... Supporting part C ... Division type reactor D ... Airtight test apparatus 1 ... Reducing agent gas supply nozzle 2 ... Silicon chloride gas supply nozzle 3 ... Exhaust gas extraction pipe 4... Gas seal material 4 a .. Cut 5. Holding metal 6. Fastening member 7. Bottom plate 8. Heater 9 ... Flange part 10. 11 ... Castable (refractory material)
DESCRIPTION OF SYMBOLS 12 ... Fastening member for jacket fixing 13 ... Ceramic board heat insulating material 14 ... Thermometer 15 ... Interior heater 16 ... Nitrogen gas inlet 17 ... Nitrogen gas outlet 18 ... Jacket 19 ... Stepped 20 ... Fitting part 21 ... Groove

Claims (6)

A gas sealing method for a fitting portion between an insertion portion and a support portion of a split reactor used in a polycrystalline silicon manufacturing apparatus,
A step of disposing a gas seal material formed by processing a braid of ceramic fibers reinforced with a metal wire with an inorganic filler and / or an organic filler into a groove formed in the fitting portion and forming it into a string shape A gas sealing method characterized by comprising:   After the step of disposing the gas seal material, the press fitting is clamped and fixed to the support portion with a tightening torque of 100 to 200 N · m via a fastening member in a state where the press fitting is pressed against the gas seal material. The gas sealing method according to claim 1, further comprising the step of:   The gas sealing method according to claim 2, further comprising a step of raising the temperature of the split reactor to 800 to 1200 ° C. after the step of fastening and fixing.   The gas sealing method according to claim 3, further comprising a step of further tightening and fixing the presser fitting to the support portion with a tightening torque of 100 to 200 N · m after the step of raising the temperature.   The gas sealing method according to any one of claims 1 to 4, wherein when the holding pressure in the split reactor is 0.5 kPa, a leak amount from the fitting portion is 5 L / hr or less.   The gas sealing method according to any one of claims 1 to 5, further comprising a step of cooling a flange portion of the support portion to which the pressing metal fitting and the fastening member are fixed using a cooling means.

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