JP2013136500A - Apparatus and method for producing trichlorosilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a heat energy loss by recovering efficiently heat generated in a reactor and utilizing the heat effectively for production of trichlorosilane.SOLUTION: In this apparatus having a reactor 2 for fluidizing ad reacting metal silicon powder Si with hydrogen chloride gas HCl, and a distillation column 3 for distilling crude trichlorosilane generated by the reaction, the reactor 2 is provided with a heating medium circulation pipe 6 through which the heating medium is circulated via the reactor 2, and a steam generator 8 for heating water by the heating medium acquiring a high temperature by absorbing heat in the reactor 2 to thereby generate steam is connected to the heating medium circulation pipe 6, and steam transport pipe 26 for utilizing steam as a heat source for the distillation column 3 is connected to the steam generator 8.

Description

  The present invention relates to a trichlorosilane production apparatus and production method for producing trichlorosilane by reacting metal silicon powder with hydrogen chloride gas.

Polycrystalline silicon used as a semiconductor material, for example, is made of trichlorosilane (silicon trichloride: SiHCl ₃ : TCS) and hydrogen as raw materials, and this mixed gas is brought into contact with a red hot silicon rod, so that hydrogen of trichlorosilane at a high temperature is obtained. It is mainly manufactured by a method (Siemens method) in which silicon is deposited on the surface of a silicon rod by reduction or thermal decomposition. In addition, the above-mentioned trichlorosilane is obtained by, for example, introducing metal silicon powder and hydrogen chloride gas into a flow type reaction furnace and reacting them to chlorinate silicon to produce crude trichlorosilane, which is purified by distillation. The one made of trichlorosilane is used.

  As an apparatus for producing this trichlorosilane, for example, there are apparatuses shown in Patent Document 1 and Patent Document 2. These trichlorosilane production devices introduce metal silicon powder and hydrogen chloride gas into the bottom of the reactor, react the metal silicon powder in the reactor while flowing with hydrogen chloride gas, and generate the generated crude trichlorosilane. It comes to take out from the upper part of. Since the reaction between the metal silicon powder and the hydrogen chloride gas is accompanied by heat generation, the reaction furnace is provided with a heat transfer tube for circulating a heat medium along the vertical direction, and absorbs the heat in the reaction furnace to the outside. It is trying to discharge.

JP-A-8-59221 JP 2010-189256 A

  By the way, the heat medium that circulates in the heat transfer tube is circulated and used by adjusting the temperature by a cooler or the like. For example, the cooling medium that has become a high temperature by absorbing the heat of the heat medium is sent to a cooling tower or the like. The heat was normally dissipated and not otherwise utilized.

  The present invention was made in view of such circumstances, and aims to efficiently recover the heat generated in the reaction furnace and effectively use it for the production of trichlorosilane to reduce the loss of heat energy. To do.

The trichlorosilane production apparatus of the present invention comprises a reaction furnace for reacting metal silicon powder while flowing with hydrogen chloride gas, and a distillation column for distilling crude trichlorosilane produced by this reaction. A heat medium circulation pipe through which the heat medium circulates through the reaction furnace is provided, and water is heated in the heat medium circulation pipe by absorbing the heat in the reaction furnace to a high temperature. A steam generator that generates steam is connected to the steam generator, and a steam transport pipe that uses the steam as a heat source of the distillation column is connected to the steam generator.
The heat generated in the reaction furnace is used as a heat source for the distillation tower, and the thermal energy loss of the entire trichlorosilane production apparatus can be reduced. The distillation tower can be applied to either a system in which the bottom of the tower is directly heated with steam or a system in which the reboiler is heated with steam, and the steam is supplied from a steam generator.

  In the trichlorosilane production apparatus of the present invention, a heat medium flow rate control means for controlling a flow rate of the heat medium to the steam generator and the cooler while further connecting a cooler to the heat medium flow tube. The steam generator may be provided with water level control means for controlling the level of water level as a steam source.

The heat in the reactor varies depending on the amount of raw material supplied, particularly hydrogen chloride gas. The heat medium flowing in the heat medium flow pipe is controlled to maintain the inside of the reaction furnace at, for example, about 300 ° C. by controlling the flow amount to the steam generator and the cooler by the heat medium flow amount control means. The Although the temperature of the heat medium sent out from the reaction furnace is lowered by passing through the steam generator, when it is desired to increase the temperature drop, cooling is performed by increasing the circulation amount to the steam generator and the cooler. Conversely, when it is desired to suppress the temperature drop, the amount of circulation to the steam generator and the cooler is reduced. As described above, by controlling the flow rate to the steam generator and the cooler, the temperature of the heat medium can be controlled to appropriately manage the temperature in the reaction furnace.
On the other hand, by controlling the pressure of the steam generated by the steam generator, the quality (pressure and temperature) of the steam sent to the distillation tower can be maintained almost constant.

  The method for producing trichlorosilane according to the present invention comprises a step of reacting metal silicon powder while flowing with hydrogen chloride gas in a reaction furnace to produce crude trichlorosilane, and a distillation operation for the produced crude trichlorosilane. A method for producing trichlorosilane comprising a distillation step for increasing purity, wherein a heat medium is circulated through the reaction furnace, and the heat medium absorbed by the heat in the reaction furnace is heated to a high temperature. Water is heated with a steam generator to generate steam, and the steam is used as a heat source for the distillation step.

  According to the present invention, while producing crude trichlorosilane in a reaction furnace, steam is generated by the reaction heat, and the steam is used as a heat source for distillation of the crude trichlorosilane, thereby reducing thermal energy loss and improving efficiency. In particular, trichlorosilane can be produced.

It is a whole lineblock diagram showing one embodiment of a trichlorosilane manufacturing device concerning the present invention. It is a whole block diagram which shows other embodiment of the trichlorosilane manufacturing apparatus which concerns on this invention.

Hereinafter, embodiments of a trichlorosilane production apparatus and production method according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, a trichlorosilane production apparatus 1 of one embodiment supplies a metal silicon powder Si and a hydrogen chloride gas HCl, and reacts the metal silicon powder Si while flowing with the hydrogen chloride gas HCl. 2 and a distillation column 3 for distilling the crude trichlorosilane produced by this reaction. The high-purity trichlorosilane obtained in the distillation column 3 is vaporized in the vaporizer 4 and then mixed with hydrogen to be used as a raw material for polycrystalline silicon as a mixed gas with hydrogen. , The polycrystalline silicon P is deposited on the surface of the red hot silicon rod S.

  In the reactor 2, the metal silicon powder Si is supplied by being pneumatically transported by a carrier gas (hydrogen chloride gas), and the hydrogen chloride gas HCl supplied to the bottom is jetted upward through a predetermined nozzle (not shown). Thus, the metal silicon powder Si reacts with the hydrogen chloride gas HCl while flowing to produce crude trichlorosilane.

The reaction furnace 2 is connected to a heat medium circulation pipe 6 through which the heat medium circulates and circulates. The heat medium flow pipe 6 is branched in parallel and provided inside the reaction furnace 2, and is branched into two outside the reaction furnace 2, and includes a heater 7, a steam generator 8, and a cooler. 9 is connected. Although the steam generator 8 and the cooler 9 are connected in series, the bypass pipes 10 and 11 are connected in parallel to each other. The heater 7 heats the heat medium in order to raise the inside of the reaction furnace 2 to a necessary temperature in the initial stage of operation of the reaction furnace 2, and the cooler 9 cools the heat medium and lowers the temperature. The steam generator 8 is for generating steam by heating water with a heat medium. The bypass pipes 10 and 11 are provided in each of the steam generator 8 and the cooler 9, and valves 12 and 13 are provided in the bypass pipes 10 and 11, respectively. , 30 can be adjusted to control the flow rate of the heat medium introduced into the steam generator 8 and the cooler 9. The heater 7 is also provided with a valve 14 for controlling the flow rate of the heat medium. A valve 29 is provided behind the steam generator 8, and the amount of steam in the steam generator 8 can be controlled by controlling the flow rate of the heat medium using the valve 29 and the valve 12. Further, a valve 30 is provided behind the cooler 9, and the temperature of the heat medium sent to the reaction furnace 2 can be controlled by controlling the flow rate of the heat medium through the valve 30 and the valves 13 and 14.
Reference numerals 15 and 16 in FIG. 1 denote thermometers for measuring the temperature of the heat medium flowing through the heat medium flow pipe 6, and the opening degree of the valve is controlled based on the measurement result. The thermometer 15 provided at the outlet of the steam generator 8 (between the steam generator 8 and the cooler 9) controls the opening degree of the valve 12 and the valve 29 of the bypass pipe 10 according to the measurement result. The flow rate of the heat medium flowing through the steam generator 8 is controlled. Further, the opening degree of the valve 13 and the valve 30 of the bypass pipe 11 is controlled by the measurement result of the thermometer 16. In this embodiment, the heat medium flow rate control means is constituted by the bypass pipes 10, 11, valves 12, 13, 29, 30 and thermometers 15, 16.
Reference numeral 17 denotes a pump that pumps the heat medium.

  The steam generator 8 stores water W therein, and the heat medium flow pipe 6 is provided in the water W so as to be immersed therein. As the water W stored inside, for example, industrial water is supplied by the water supply pipe 21. In the steam generator 8, a liquid level gauge 22 is provided for detecting the water level of the water W, and a valve 23 is provided in the water supply pipe 21, and the steam generator 8 detected by the liquid level gauge 22. The level of the water W in the steam generator 8 is controlled so as to be maintained within a predetermined range by controlling the opening and closing of the valve 23 in accordance with the water level of the water W inside. In this embodiment, the valve 23 and the liquid level gauge 22 constitute the water level control means of the present invention. Reference numeral 24 is a pump provided in the water supply pipe 21, and reference numeral 25 is a drain pipe from the steam generator 8.

When the steam generated in the steam generator 8 reaches a predetermined temperature and pressure (for example, 0.1 to 0.3 MPaG at 120 to 145 ° C.), the steam is led to the steam transport pipe 26 and adjusted to a predetermined pressure by the pressure adjustment valve 27. After that, it is sent to the distillation column 3.
In the illustrated example, the distillation tower 3 has a reboiler 28 connected to the bottom of the tower, and the steam transport pipe 26 is installed so as to pass through the reboiler 28, and the bottom liquid is heated in the reboiler 28. Yes.

In the trichlorosilane production apparatus 1 configured as described above, when producing trichlorosilane to be supplied to the polycrystalline silicon precipitation furnace 5, metal silicon powder Si and hydrogen chloride gas HCl are supplied into the reaction furnace 2, To produce crude trichlorosilane (crude trichlorosilane production step), and the resulting crude trichlorosilane is distilled in the distillation tower 3 to produce high-purity trichlorosilane (distillation step).
Hereinafter, these steps will be described in detail.

In the crude trichlorosilane production step, the heat medium is circulated in the reaction furnace 2 and the temperature of the heat medium is raised by the heater 7. While confirming the temperature of the heat medium with the thermometer 15, the temperature of the reaction furnace 2 is gradually raised.
In the initial operation of the reaction furnace 2, the valve 14 is opened and the flow path to the heater 7 is connected to the heater 7 by opening / closing control of the other valves 12, 13, 29, 30. When the heated high-temperature heat medium flows, the inside of the reaction furnace 2 is heated to a temperature (for example, 300 ° C.) necessary for the reaction between the metal silicon powder Si and the hydrogen chloride gas HCl. When the reaction between the metal silicon powder Si and the hydrogen chloride gas HCl starts, heat is gradually generated, so that the valve 14 leading to the heater 7 is closed and the other valves 12, 13, 29, 30 are opened and closed stepwise. Controlled.
First, when the temperature in the reaction furnace 2 reaches a certain range, the reaction is started, so that the temperature in the furnace rises and the temperature of the heat medium tends to rise at the same time. The temperature transition of the heat medium is confirmed, the valve 12 and the valve 30 are opened, the heat medium is passed through the cooler 9, the temperature of the heat medium is stabilized, and the temperature in the reaction furnace 2 is kept within a predetermined temperature range. The temperature of the heat medium is adjusted and stabilized by adjusting the opening degree of the valves 13 and 30 based on the measured value of the thermometer 15 so as to enter. The heat medium cooled by the cooler 9 is guided to the reaction furnace 2 for use as a refrigerant in the reaction furnace 2.

In this case, the temperature of the heat medium is detected by thermometers 15 and 16 provided in the heat medium flow pipe 6 so that the temperature in the reaction furnace 2 is maintained at around 300 ° C. (for example, 290 to 310 ° C.). Be controlled. The temperature in the reaction furnace 2 varies depending on the amount of raw material supplied, particularly hydrogen chloride gas HCl. For this reason, the temperature of the heat medium also fluctuates, but when the temperature is not too low, the heat medium is guided to the steam generator 8.
At this time, while checking the temperature of the thermometers 15 and 16, the valve 29 is gradually opened, and the opening degree is adjusted so that there is no sudden change in temperature. At this time, the opening degree is adjusted while confirming that the temperature of the heat medium entering the reaction furnace 2 is within a predetermined temperature range. In this case, the valve 12 may be closed as much as the valve 29 is opened.
The steam generator 8 stores water W supplied from the water supply pipe 21, and water is heated by the heat medium flow pipe 6 immersed in the water to generate steam. As described above, when the steam generated in the steam generator 8 reaches a predetermined temperature and pressure, it is led out to the steam transport pipe 26 and sent to the distillation column 3.
When the temperature measured by the thermometers 15 and 16 becomes stable (when the temperature measured by the thermometer 16 approaches the temperature measured by the thermometer 15), a set value for the thermometer 16 is provided. A stable heat medium is circulated by adjusting the opening of the valve 30, the valve 13 or the valve 29, or the valve 12 so that the temperature difference between the measured temperatures is less than a certain value (for example, 5 ° C. or less).

When the heat medium flowing through the heat medium flow pipe 6 becomes too high, the opening degree of the valves 12 and 13 provided in the bypass pipes 10 and 11 of the steam generator 8 and the cooler 9 is reduced. It is adjusted so that the opening degree of the valves (valves 29, 30) on the outlet side of the steam generator 8 and the cooler 9 is increased, and the heat medium is sent to the steam generator 8 and the cooler 9 to be cooled. . When the temperature of the heat medium is lowered, the opening degree of the valve 30 is adjusted so that the opening degree of the valve 13 provided in the bypass pipe 11 of the cooler 9 is increased. Moreover, the opening degree of the valve 12 and the valve 29 provided in the bypass pipe 10 of the steam generator 8 is also adjusted as appropriate. The distribution ratio of the heat medium between the steam generator 8 and the cooler 9 is controlled based on the detection results of the thermometer 15 at the outlet of the steam generator 8 and the thermometer 16 after the cooler 9 outlet.
Further, when the temperature of the heat medium is excessively lower than the set temperature due to temperature adjustment of the cooler 9 or accompanying temperature fluctuation, adjustment such as increasing the opening of the valve 13 of the bypass pipe 11 is performed intermittently. The flow rate of the heat medium is controlled so as to maintain the reaction furnace temperature within a predetermined temperature range.

In this way, while controlling the flow of the heat medium to the steam generator 8, the cooler 9, and the bypass pipes 10, 11, the temperature in the reaction furnace 2 is maintained within a predetermined temperature range and the metal silicon powder Si and the chloride are maintained. Hydrogen gas HCl is allowed to react stably to produce crude trichlorosilane, while steam is generated in the steam generator 8 using the heat at that time. In this case, since the flow rate of the heat medium to the steam generator 8 fluctuates, by adjusting the amount of water supplied from the water supply pipe 21 while monitoring the liquid level of the steam generator 8 with the liquid level gauge 22, The amount of steam can be adjusted.
The crude trichlorosilane is distilled in the distillation tower 3 (distillation step), and the steam generated in the steam generator 8 is used as a heat source at that time. It is supplied to the furnace 5 and used for the production of polycrystalline silicon P.

  As described above, the trichlorosilane production apparatus 1 recovers heat generated in the reaction furnace 2 while producing crude trichlorosilane in the reaction furnace 2, generates steam using the heat, By using the steam in the distillation column 3 in the post-process, the crude trichlorosilane is distilled to increase the purity, and high-purity trichlorosilane is produced. The heat generated in the reactor 2 is effectively used in the post-process. Utilizing it, it is possible to efficiently produce trichlorosilane with reduced thermal energy loss.

FIG. 2 shows an example of an embodiment of a trichlorosilane production apparatus having a plurality of reaction furnaces. In the present embodiment, the same reference numerals are assigned to common elements as in the previous embodiment, and the description is simplified. Moreover, in FIG. 2, some components, such as a distillation tower and a polycrystalline silicon precipitation furnace, are abbreviate | omitted, About the omitted part, it is the same as that of one Embodiment.
In this trichlorosilane manufacturing apparatus 51, each reaction furnace 2 and one steam generator 8 are connected in parallel by a heat medium flow pipe 6, and each heat medium flow pipe 6 is connected to the steam generator 8. On the other hand, a heater 7 in parallel and a cooler 9 in series with the steam generator 8 are provided, and bypass pipes 10 and 11 are connected to the steam generator 8 and the cooler 9, respectively.

  This embodiment is also operated in the same manner as in the embodiment of FIG. 1, but is operated and stabilized one by one for the two reactors. And the heat generated in these reactors 2 can be efficiently recovered and effectively used for the production of trichlorosilane, and the loss of thermal energy can be reduced.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, although the distillation tower provided with the reboiler was shown in the said embodiment, you may make it heat the bottom of a distillation tower directly with a vapor | steam.
Further, a method may be used in which a form in which steam from the outside is introduced into the steam transport pipe in accordance with fluctuations in the amount of steam generated, and stable steam is sent to the distillation tower. In addition, a method may be used in which the heat medium of a plurality of reactors is supplied to the steam generator in accordance with fluctuations in the amount of steam generated, and stable steam is sent to the distillation tower.
Further, when the heat medium flow rate ratio between the steam generator 8 and the cooler 9 is controlled based on the detection results of the thermometer 15 at the outlet of the steam generator 8 and the thermometer 16 after the outlet of the cooler 9. However, the temperature may be controlled by the preset temperature or temperature range of the thermometers 15 and 16.
In addition, drain in a distillation column, reboiler, or steam generator may be used as a steam water source.
In the steam generator 8, the amount of steam generated in the steam generator 8 also varies by controlling the flow rate of the heat medium with the valves 12, 13, 29, and 30. A method of monitoring the amount of change per unit time of the level with the liquid level gauge 22 and reflecting the result in the control of the flow rate of the heat medium may be used.

DESCRIPTION OF SYMBOLS 1 Trichlorosilane production apparatus 2 Reactor 3 Distillation tower 4 Vaporizer 5 Polycrystalline silicon precipitation furnace 6 Heat-medium flow pipe 7 Heater 8 Steam generator 9 Cooler 10, 11 Bypass pipe 12-14 Valve 15, 16 Thermometer 17 Pump 21 Water supply pipe 22 Level gauge 23 Valve 24 Pump 25 Drain pipe 26 Steam transport pipe 27 Pressure control valve 28 Reboiler 29, 30 Valve 51 Trichlorosilane production equipment

Claims (3)

  A reaction furnace for reacting metal silicon powder while flowing with hydrogen chloride gas; and a distillation column for distilling crude trichlorosilane produced by the reaction. The reactor is heated via the reaction furnace. A heat medium circulation pipe through which the medium circulates is provided, and a steam generator that generates steam by heating water with a heat medium that has absorbed the heat in the reaction furnace and has reached a high temperature is provided in the heat medium circulation pipe. An apparatus for producing trichlorosilane, wherein the apparatus is connected and a steam transport pipe that uses the steam as a heat source of the distillation column is connected to the steam generator.   The heat medium circulation pipe is further connected to a cooler, and is provided with a heat medium flow rate control means for controlling the flow rate of the heat medium to the steam generator and the cooler. The apparatus for producing trichlorosilane according to claim 1, further comprising a water level control means for controlling the level of water as a steam source.   A trichlorosilane production step for reacting metal silicon powder with hydrogen chloride gas in a reaction furnace to produce crude trichlorosilane, and a distillation step for increasing the purity of the produced crude trichlorosilane by distillation operation. In the chlorosilane production method, a heat medium is circulated and circulated through the reaction furnace, and water is heated by a steam generator by the heat medium that has absorbed the heat in the reaction furnace and has become high temperature. A method for producing trichlorosilane, characterized in that the steam is generated and used as a heat source for the distillation step.

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