Hydrogen for polysilicon production, impurity removal method and system, polysilicon production method and system

Abstract

The present invention provides a method and system for purifying hydrogen used in polysilicon production, as well as a method and system for polysilicon production. The purification method includes the following steps: introducing hydrogen used in polysilicon production into boiling trichlorosilane so that the internal moisture reacts with trichlorosilane, and then making the gas phase escaping from trichlorosilane contact with the atomized trichlorosilane sprayed downwards so that the remaining water vapor in it reacts with trichlorosilane to obtain a water-removed gas phase; the water-removed gas phase is then condensed to liquefy the vaporized trichlorosilane in it, and hydrogen used in polysilicon production with impurities removed is obtained. The present invention can dry the moisture in hydrogen used in polysilicon production to less than 1 ppm without introducing external impurities.

Description

Technical Field

[0001] The present invention relates to the technical field of gas purification, and in particular to a method and system for purifying hydrogen used in polysilicon production, a method and system for producing polysilicon, and a method and system for removing impurities in hydrogen used in polysilicon production. Background Art

[0002] Hydrogen is an important chemical raw material and also an important fuel. Common methods for preparing hydrogen include water electrolysis for hydrogen production or water gas method for hydrogen production. No matter which method is used, the hydrogen produced contains a trace amount of oxygen and moisture impurities, and the presence of impurities seriously affects the quality of hydrogen.

[0003] In the process of producing trichlorosilane, the raw material for polysilicon production, hydrogen is first used as a raw material to synthesize hydrogen chloride, and then trichlorosilane is synthesized by reacting hydrogen chloride with silicon powder. The presence of oxygen and moisture will affect the conversion rate of trichlorosilane synthesis and the operation efficiency of the system. Therefore, whether the impurities can be removed is very important for obtaining high-quality hydrogen.

[0004] The prior art removes the water in hydrogen by liquefying it with a cooler, or by contacting the hydrogen containing water vapor with an adsorbent and trichlorosilane, adsorbing and absorbing the moisture into the adsorbent and trichlorosilane to remove the moisture and reduce the dew point. However, the efficiency of water removal by cooling is limited and only part of the water in hydrogen can be removed. When using a solid adsorbent or liquid trichlorosilane, it is inevitable to introduce external impurities, which affects the quality of the final product polysilicon. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide, in view of the above deficiencies in the prior art, a method for removing impurities in hydrogen used in polysilicon production that can improve the water removal rate in hydrogen without introducing external impurities, and also correspondingly provide hydrogen obtained by the impurity removal method, a polysilicon production method and system including the impurity removal method, and a system for implementing the impurity removal method.

[0006] The technical solution adopted to solve the technical problem of the present invention is as follows:

[0007] The present invention provides a method for removing impurities in hydrogen used in polysilicon production, including the following steps:

[0008] Introduce the hydrogen used in polysilicon production into boiling trichlorosilane so that the internal water reacts with trichlorosilane, and the gas phase escaping from trichlorosilane contacts the atomized trichlorosilane sprayed downwards so that the remaining water vapor in it reacts with trichlorosilane to obtain a water-removed gas phase;

[0009] The water-removed gas phase is further condensed to liquefy the vaporized trichlorosilane in it to obtain the hydrogen for polysilicon production with impurities removed.

[0010] Optionally, the liquefied trichlorosilane obtained by condensing the water-removed gas phase is atomized to form the atomized trichlorosilane.

[0011] Optionally, before introducing the hydrogen gas for polysilicon production into trichlorosilane, it further includes: catalytically oxidizing the hydrogen gas for polysilicon production to convert the oxygen carried therein into water.

[0012] Optionally, all the solid phases produced by the reaction of the water in the hydrogen gas for polysilicon production with trichlorosilane enter the boiling trichlorosilane. When the mass ratio of the solid phase to the liquid phase in the boiling trichlorosilane is greater than the set value, the trichlorosilane containing the solid phase is flash-evaporated. The trichlorosilane vapor obtained after flash evaporation is pressurized and liquefied and then heated to form the boiling trichlorosilane.

[0013] Optionally, the temperature of the boiling trichlorosilane is 45 - 60 °C, the temperature of the atomized trichlorosilane is -15 to -5 °C, and the set value is 25% - 35%.

[0014] Optionally, in an environment of 0.2 - 0.3 MpaG, the gas phase escaping from trichlorosilane is brought into contact with the atomized trichlorosilane.

[0015] The present invention also provides hydrogen gas for polysilicon production prepared by the above method.

[0016] The present invention also provides a polysilicon production method, including the following steps:

[0017] Using the purified hydrogen gas for polysilicon production obtained by the above method as a raw material to synthesize hydrogen chloride,

[0018] Reacting the hydrogen chloride with silicon powder to synthesize trichlorosilane,

[0019] Reducing the trichlorosilane to obtain polysilicon.

[0020] The present invention also provides a hydrogen gas purification system for polysilicon production, including a scrubbing tower and a condenser,

[0021] The lower part of the scrubbing tower is used to store boiling trichlorosilane and is provided with an inlet pipe for introducing the hydrogen gas for polysilicon production into the boiling trichlorosilane to make part of the water therein react with trichlorosilane;

[0022] The upper part of the scrubbing tower is provided with a spraying structure for atomizing and spraying trichlorosilane. The gas phase escaping from the boiling trichlorosilane is brought into contact with the atomized trichlorosilane to make the remaining water in the escaping gas phase react with trichlorosilane to obtain a water-removed gas phase;

[0023] The condenser is connected to the first gas pipe at the top of the scrubbing tower and is used for condensing the water-removed gas phase to liquefy the vaporized trichlorosilane therein, thereby obtaining purified hydrogen gas for polysilicon production.

[0024] Optionally, a reflux pipe is provided between the condenser and the spraying structure for introducing the liquefied trichlorosilane into the spraying structure.

[0025] Optionally, a catalytic reactor is further included.

[0026] The outlet of the catalytic reactor is connected to the inlet pipe of the scrubbing tower for catalytic oxidation of the hydrogen for polysilicon production before it enters the scrubbing tower, so that the oxygen therein is converted into water.

[0027] Optionally, a flash tank and a pressurizer are further included. A first discharge pipe is provided between the flash tank and the scrubbing tower, and a second opening and closing valve is provided on the first discharge pipe.

[0028] The flash tank is used to receive the trichlorosilane containing solid phase sent from the scrubbing tower through the first discharge pipe and perform flash evaporation on it to obtain trichlorosilane vapor.

[0029] The pressurizer is respectively connected to the outlet of the flash tank and the inlet of the scrubbing tower, and is used to receive the trichlorosilane vapor sent from the flash tank, pressurize and liquefy it, and then send it back to the scrubbing tower.

[0030] Optionally, a reboiler is provided at the lower part of the scrubbing tower for heating the trichlorosilane at the lower part of the scrubbing tower to a temperature above its boiling point.

[0031] The present invention also provides a polysilicon production system, including a reduction furnace and a material supply unit, and the material supply unit includes the above-mentioned hydrogen impurity removal system for polysilicon production.

[0032] In the present invention, by using the intermediate product trichlorosilane in polysilicon production as the desiccant for hydrogen impurity removal, trichlorosilane reacts with the water in hydrogen to generate precipitation, HCl and hydrogen. The small amount of HCl and vaporized trichlorosilane introduced into the dried gas phase are all raw materials or by-products in the polysilicon production reaction, thereby minimizing the introduction of external impurities and ensuring the quality of the final product polysilicon.

[0033] Moreover, since the water content of the hydrogen for polysilicon production is extremely low, in the present invention, the hydrogen is introduced into the boiling trichlorosilane, so that the hydrogen is in full contact with the trichlorosilane in the form of bubbles, so that the internal water reacts with the boiling trichlorosilane. Then, the gas phase (hydrogen with part of the water removed + trichlorosilane vapor generated by the boiling trichlorosilane) escaping from the boiling trichlorosilane is contacted with the atomized trichlorosilane sprayed down. Under the pressure of the atomized trichlorosilane, the water in the gas phase can react repeatedly with the vaporized and atomized trichlorosilane. Practice shows that the present invention can dry the water in the hydrogen for polysilicon production to less than 1PPm. The trichlorosilane vapor mixed in the dried gas phase is condensed, so that clean hydrogen can be obtained. Brief Description of the Drawings

[0034] Figure 1 FIG. 1 is a schematic structural diagram of a hydrogen purification system for polysilicon production provided in Embodiment 4 of the present invention.

[0035] In the figure: 1, intake pipe; 2, scrubbing tower; 21, spraying structure; 3, reboiler; 4, first gas pipe; 5, first discharge pipe; 6, condenser; 7, reflux pipe; 8, second gas pipe; 9, catalytic reactor; 10, flash tank; 11, pressurizer; 12, second discharge pipe; 13, reflux pump; 14, demister. Detailed Description of the Embodiments

[0036] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the scope of the present invention.

[0037] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of description and simplification, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0038] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "connected", "set", "installed", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The present invention provides a method for purifying hydrogen for polysilicon production, including the following steps:

[0041] Introduce the hydrogen for polysilicon production into boiling trichlorosilane so that the internal moisture reacts with trichlorosilane. The gas phase escaping from trichlorosilane then contacts the atomized trichlorosilane spraying downward so that the remaining water vapor in it reacts with trichlorosilane to obtain a water-removed gas phase.

[0042] The water-removed gas phase is further condensed to liquefy the vaporized trichlorosilane therein, obtaining hydrogen gas for polysilicon production with impurities removed.

[0043] The present invention also provides hydrogen gas for polysilicon production prepared by the above method.

[0044] The present invention also provides a polysilicon production method, including the following steps:

[0045] Using the hydrogen gas for polysilicon production with impurities removed obtained by the above method as a raw material to synthesize hydrogen chloride,

[0046] Reacting the hydrogen chloride with silicon powder to synthesize trichlorosilane,

[0047] Reducing the trichlorosilane to obtain polysilicon.

[0048] The present invention also provides a hydrogen gas impurity removal system for polysilicon production, including a scrubbing tower and a condenser.

[0049] The lower part of the scrubbing tower is used to store boiling trichlorosilane and is provided with an inlet pipe for introducing hydrogen gas for polysilicon production into the boiling trichlorosilane, so that part of the water inside reacts with the trichlorosilane.

[0050] The upper part of the scrubbing tower is provided with a spraying structure for spraying the trichlorosilane atomized. The gas phase escaping from the boiling trichlorosilane contacts the atomized trichlorosilane, enabling the remaining water in the escaping gas phase to react with the trichlorosilane to obtain a water-removed gas phase.

[0051] The condenser is connected to the first gas pipe at the top of the scrubbing tower and is used to condense the water-removed gas phase to liquefy the vaporized trichlorosilane therein, thereby obtaining hydrogen gas for polysilicon production with impurities removed.

[0052] The present invention also provides a polysilicon production system, including a reduction furnace and a material supply unit, and the material supply unit includes the above hydrogen gas impurity removal system for polysilicon production.

[0053] Example 1:

[0054] This example provides a method for removing impurities from hydrogen gas for polysilicon production, including the following steps:

[0055] Introducing hydrogen gas for polysilicon production into boiling trichlorosilane so that part of the water inside reacts with the trichlorosilane. The gas phase escaping from the trichlorosilane further contacts the atomized trichlorosilane spraying downwards, enabling the remaining water vapor inside to react with the trichlorosilane to obtain a water-removed gas phase.

[0056] The water-removed gas phase is further condensed to liquefy the vaporized trichlorosilane therein, obtaining hydrogen gas for polysilicon production with impurities removed.

[0057] By using trichlorosilane, an intermediate product in polysilicon production, as a desiccant for hydrogen purification, trichlorosilane reacts with water in hydrogen to form a precipitate, HCl, and hydrogen. A small amount of HCl introduced into the dried gas phase and vaporized trichlorosilane are both raw materials or by-products in the polysilicon production reaction, thus minimizing the introduction of external impurities and ensuring the quality of the final product, polysilicon.

[0058] Moreover, since the water content in the hydrogen used for polysilicon production is extremely low, in the present invention, hydrogen is introduced into boiling trichlorosilane, so that hydrogen is in full contact with trichlorosilane in a bubbling manner, enabling the internal water to react with the boiling trichlorosilane. Then, the gas phase escaping from the boiling trichlorosilane (hydrogen with some water removed + trichlorosilane vapor generated by the boiling trichlorosilane) is brought into contact with atomized trichlorosilane sprayed downwards. Under the pressure of the atomized trichlorosilane, the water in the gas phase can react repeatedly with the vaporized and atomized trichlorosilane. Practice has shown that the present invention can dry the water in the hydrogen used for polysilicon production to less than 1 ppm. The trichlorosilane vapor mixed in the dried gas phase is condensed to obtain clean hydrogen.

[0059] In this embodiment, the liquefied trichlorosilane obtained by condensing the water-removed gas phase is atomized again to form the atomized trichlorosilane. On the one hand, it realizes the recycling of trichlorosilane, and on the other hand, it further reduces the introduction of external impurities.

[0060] In this embodiment, before introducing the hydrogen used for polysilicon production into trichlorosilane, it also includes: catalytic oxidation of the hydrogen used for polysilicon production to convert the oxygen carried therein into water, thereby further reducing the impurities in hydrogen that affect the quality of polysilicon.

[0061] The catalyst is a mature product and can be obtained through commercial purchase. Its active components generally include nickel, palladium, and copper, and its carriers generally include activated alumina, silica, etc.

[0062] In this embodiment, the solid-phase SiO produced by the reaction of water in the hydrogen used for polysilicon production with trichlorosilane 2 all enters the boiling trichlorosilane. When the mass ratio of the solid-phase SiO in the boiling trichlorosilane 2 to the liquid-phase trichlorosilane is greater than the set value, the trichlorosilane containing the solid-phase SiO 2 is flash-evaporated at a flash-evaporation pressure of 50 KPa. The obtained trichlorosilane vapor is pressurized and liquefied, and then heated to form the boiling trichlorosilane.

[0063] The set value is 25% - 35%.

[0064] Due to the solid-phase product SiO formed by the reaction of water and trichlorosilane 2The particles are extremely fine and exist in trichlorosilane in a suspended manner. As the number of suspended particles increases, the fluidity of trichlorosilane becomes worse. The applicant's practice shows that when the ratio of suspended particles to liquid trichlorosilane is greater than about 30%, the trichlorosilane containing solid phase is difficult to discharge. Therefore, when the ratio of the solid phase to trichlorosilane in the trichlorosilane containing solid phase reaches the set value, the trichlorosilane containing solid phase is discharged.

[0065] The trichlorosilane containing solid phase can be flash-evaporated to separate trichlorosilane and SiO 2 The trichlorosilane can be recycled back to the polysilicon production system for reuse, thereby reducing the production cost. Moreover, compared with other liquid absorbents such as using the by-product silicon tetrachloride in the polysilicon production system as a desiccant (silicon tetrachloride reacts with water to form H 4 SiO 4 gel, resulting in difficult recovery of silicon tetrachloride), trichlorosilane is convenient to recover as a desiccant, greatly improving the recovery efficiency and reducing the recovery cost.

[0066] Specifically, the trichlorosilane vapor obtained by flash evaporation is pressurized and liquefied, heated to boiling, and then participates in the drying of hydrogen for polysilicon production. On the one hand, the recycling of trichlorosilane is realized, and on the other hand, the introduction of external impurities is further reduced.

[0067] In this embodiment, the temperature of the boiling trichlorosilane is 45 - 60 °C, and the temperature of the atomized trichlorosilane is -15 to -5 °C.

[0068] In this embodiment, in an environment of 0.2 - 0.3 MpaG, the gas phase escaping from trichlorosilane is brought into contact with the atomized trichlorosilane.

[0069] Example 2:

[0070] This embodiment provides hydrogen for polysilicon production prepared by the method of Example 1.

[0071] Example 3:

[0072] This embodiment provides a polysilicon production method, including the following steps:

[0073] Using the purified hydrogen for polysilicon production obtained by the method of Example 1 as a raw material to synthesize hydrogen chloride,

[0074] Reacting the hydrogen chloride with silicon powder to synthesize trichlorosilane,

[0075] Reducing the trichlorosilane to obtain polysilicon.

[0076] Example 4:

[0077] As Figure 1As shown in the figure, this embodiment provides a hydrogen purification system for polysilicon production, including a scrubbing tower 2, a condenser 6, a catalytic reactor 9, a flash tank 10, and a pressurizer 11.

[0078] The lower part of the scrubbing tower 2 is used to store boiling trichlorosilane (31.8 °C), and is provided with an inlet pipe 1. The inlet pipe 1 is used to supply hydrogen for polysilicon production into the boiling trichlorosilane, so that the internal moisture reacts with trichlorosilane.

[0079] The upper part of the scrubbing tower 2 is provided with a spraying structure 21 for spraying trichlorosilane atomically. The gas phase escaping from the boiling trichlorosilane contacts the atomized trichlorosilane, so that the remaining moisture in the escaping gas phase reacts with trichlorosilane to obtain a water-removed gas phase.

[0080] The condenser 6 is connected to the first gas pipe 4 at the top of the scrubbing tower 2, and is used to condense the water-removed gas phase to liquefy the vaporized trichlorosilane therein, so as to obtain hydrogen for polysilicon production with impurities removed.

[0081] The source of hydrogen for polysilicon production is hydrogen produced by electrolyzing water, hydrogen obtained by electrolyzing brine, and hydrogen produced by water gas.

[0082] Thus, by using the intermediate product trichlorosilane in polysilicon production as a desiccant for hydrogen purification, the trichlorosilane in the scrubbing tower 2 reacts with the water in hydrogen to generate precipitation, HCl, and hydrogen. The small amount of HCl and vaporized trichlorosilane introduced by the dried hydrogen are all raw materials or by-products in the polysilicon production reaction, thus minimizing the introduction of external impurities and ensuring the quality of the final product polysilicon.

[0083] Moreover, since the moisture content of hydrogen for polysilicon production is extremely low, in the present invention, hydrogen is introduced into the boiling trichlorosilane in the scrubbing tower 2, so that hydrogen is in full contact with trichlorosilane in a bubbling manner, and the internal moisture reacts with the boiling trichlorosilane. The gas phase escaping from the boiling trichlorosilane (hydrogen with part of the water removed + trichlorosilane vapor generated by boiling trichlorosilane) contacts the trichlorosilane atomized by the spraying structure 21. Under the pressure of the atomized trichlorosilane, the water in the gas phase can react with the vaporized and atomized trichlorosilane repeatedly. Practice shows that the present invention can dry the moisture in hydrogen for polysilicon production to below 1 ppm. The trichlorosilane vapor mixed in the dried hydrogen is condensed by the condenser, so that clean hydrogen can be obtained.

[0084] In this embodiment, a reflux pump 13 is provided between the spraying structure 21 and the condenser 6. Since the atomization pressure drop of the spraying structure 21 is very large, the reflux pump 13 is used to increase the pressure to press the liquefied trichlorosilane in the condenser 6 into the spraying structure 21.

[0085] In this embodiment, a second gas guide pipe 8 is provided on the condenser 6 for guiding out the hydrogen gas used in polysilicon production after impurity removal. A demister 14 is provided on the second gas guide pipe 8 to remove the trichlorosilane mist entrained in the hydrogen gas.

[0086] In this embodiment, a reflux pipe 7 is provided between the condenser 6 and the spray structure 21 for guiding the liquefied trichlorosilane into the spray structure 21. On the one hand, it realizes the recycling of trichlorosilane, and on the other hand, it further reduces the introduction of external impurities.

[0087] In this embodiment, the outlet of the catalytic reactor 9 is connected to the inlet pipe of the scrubbing tower 2 for catalytic oxidation of the hydrogen gas used in polysilicon production before it enters the scrubbing tower 2, so that the oxygen in it is converted into water. Thereby further reducing the impurities in the hydrogen gas that affect the quality of polysilicon.

[0088] In this embodiment, a first discharge pipe 5 is provided at the bottom of the scrubbing tower 2, and a first opening and closing valve is provided on the first discharge pipe 5.

[0089] In this embodiment, the set value is 25%-35%.

[0090] The solid-phase SiO produced by the reaction of water in the hydrogen gas used in polysilicon production with trichlorosilane 2 All enter the trichlorosilane in the lower part of the scrubbing tower 2. Due to SiO 2 The particles are extremely fine and exist in the trichlorosilane liquid in a suspended manner. When the suspended particles become more and more, the fluidity of trichlorosilane becomes worse. The applicant's practice shows that when the ratio of suspended particles to liquid trichlorosilane is greater than about 30%, the trichlorosilane containing solid phase is difficult to discharge. Therefore, when the ratio of the solid-phase SiO in the trichlorosilane containing solid phase detected by off-line sampling reaches the set value, the first opening and closing valve is opened to discharge the trichlorosilane containing solid phase, and new trichlorosilane is added to the scrubbing tower 2. 2 When the ratio of the solid-phase SiO in the trichlorosilane containing solid phase detected by off-line sampling reaches the set value, the first opening and closing valve is opened to discharge the trichlorosilane containing solid phase, and new trichlorosilane is added to the scrubbing tower 2.

[0091] In this embodiment, the flash tank 10 is connected to the first discharge pipe 5 for receiving the trichlorosilane containing solid-phase SiO 2 discharged from the scrubbing tower 2 and flashing it to obtain trichlorosilane vapor.

[0092] Thus, through flashing, trichlorosilane and SiO 2 can be separated, and trichlorosilane can be returned to the polysilicon production system for recycling, thereby reducing the production cost. And, compared with other liquid absorbents such as using the by-product silicon tetrachloride in the polysilicon production system as a desiccant (silicon tetrachloride reacts with water to form a gel, resulting in difficult recovery of silicon tetrachloride), trichlorosilane as a desiccant is convenient to recycle, greatly improving the recovery efficiency and reducing the recovery cost.

[0093] In this embodiment, a pressurizer 11 is further included. The pressurizer 11 is respectively connected to the outlet of the flash tank and the inlet of the scrubbing tower, and is used to receive the trichlorosilane vapor sent from the flash tank 10, pressurize and liquefy it, and then send it back to the scrubbing tower 2.

[0094] The trichlorosilane vapor obtained by flashing is pressurized and liquefied and then returned to the scrubbing tower 2 as a desiccant. On the one hand, the recycling of trichlorosilane is realized, and on the other hand, the introduction of external impurities is further reduced.

[0095] In this embodiment, a second discharge pipe 12 is provided at the bottom of the flash tank 10, and a second opening and closing valve is provided on the second discharge pipe. When it is observed that only solid-phase SiO remains in the flash tank 10 2 , the second opening and closing valve is opened, and the solid phase is discharged through the second discharge pipe 12.

[0096] In this embodiment, a reboiler 3 is provided at the lower part of the scrubbing tower 2, and is used to heat the trichlorosilane at the lower part of the scrubbing tower 2 to a temperature above its boiling point (31.8 °C).

[0097] The process flow of the hydrogen purification system for polysilicon production in this embodiment is as follows:

[0098] The crude hydrogen enters the catalytic reactor 9. The oxygen in the hydrogen reacts with the hydrogen under the action of the catalyst to generate water. The reacted gas enters the scrubbing tower 2 through the inlet pipe 1, and contacts the boiling trichlorosilane in the bottom of the scrubbing tower 2 in a bubbling manner to remove part of the moisture in the hydrogen. The unremoved moisture and the hydrogen flow upward from the bottom of the tower kettle and repeatedly contact the trichlorosilane vapor in the scrubbing tower 2 and the atomized silicon tetrachloride sprayed from the top of the tower. The moisture in the hydrogen reacts with the trichlorosilane to generate SiO 2 , hydrogen chloride and hydrogen. The generated SiO 2 is enriched in the tower kettle. The hydrogen with moisture removed and part of the trichlorosilane vapor come out from the top of the scrubbing tower and enter the condenser 6 through the first guide pipe 4. The trichlorosilane is condensed into a liquid and returns to the scrubbing tower 2 through the reflux pipe 7. The hydrogen after purification passes through the second guide pipe 8 to the hydrogen chloride synthesis process. A reboiler 3 is provided at the bottom of the scrubbing tower 2, and part of the trichlorosilane is vaporized by steam heating.

[0099] When the mass ratio of the suspended solid SiO 2 in the trichlorosilane in the tower kettle to the trichlorosilane liquid reaches 30%, the first opening and closing valve is opened, and the trichlorosilane liquid containing solid-phase SiO 2 is discharged to the flash tank 10 through the first discharge pipe 5. The flash tank 10 flashes the liquid-solid mixture fed into it, and the obtained trichlorosilane vapor is pressurized and liquefied by the pressurizer 11 and then returned to the scrubbing tower 2 for recycling. When only the solid phase remains in the flash tank 10, the second opening and closing valve is opened, and the SiO 2The powder is discharged through the second discharge pipe 12.

[0100] Example 5

[0101] This embodiment provides a polysilicon production system, including a reduction furnace and a material supply unit. The material supply unit includes the hydrogen purification system for polysilicon production in Example 4.

[0102] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A method for purifying hydrogen used in polysilicon production, characterized in that, it comprises the following steps: Using trichlorosilane as a desiccant for hydrogen purification, introducing the hydrogen used in polysilicon production into boiling trichlorosilane so that the internal water reacts with trichlorosilane, and the gas phase escaping from trichlorosilane contacts the atomized trichlorosilane sprayed downward so that the remaining water vapor in it reacts with trichlorosilane to obtain a dehydrated gas phase; The dehydrated gas phase is then condensed to liquefy the vaporized trichlorosilane therein to obtain the purified hydrogen for polysilicon production.

2. The method for purifying hydrogen used in polysilicon production according to claim 1, characterized in that, the liquefied trichlorosilane obtained by condensing the dehydrated gas phase is atomized again to form the atomized trichlorosilane.

3. The method for purifying hydrogen used in polysilicon production according to claim 1, characterized in that, before introducing the hydrogen used in polysilicon production into trichlorosilane, it further includes: catalytically oxidizing the hydrogen used in polysilicon production to convert the oxygen carried therein into water.

4. The method for purifying hydrogen used in polysilicon production according to claim 1, characterized in that, the solid phase produced by the reaction of water in the hydrogen for polysilicon production with trichlorosilane all enters the boiling trichlorosilane. When the mass ratio of the solid phase to the liquid phase in the boiling trichlorosilane is greater than the set value, the trichlorosilane containing the solid phase is flash distilled, and the trichlorosilane vapor obtained after flash distillation is pressurized, liquefied and heated to form the boiling trichlorosilane.

5. The method for purifying hydrogen used in polysilicon production according to claim 4, characterized in that, the temperature of the boiling trichlorosilane is 45 - 60 °C, the temperature of the atomized trichlorosilane is -15 ~ -5 °C, and the set value is 25% - 35%.

6. The method for purifying hydrogen used in polysilicon production according to claim 5, characterized in that, in an environment of 0.2 - 0.3 MpaG, the gas phase escaping from trichlorosilane is made to contact the atomized trichlorosilane.

7. Hydrogen for polysilicon production prepared by the method according to any one of claims 1 - 6.

8. A polysilicon production method, characterized in that, it comprises the following steps: using the purified hydrogen for polysilicon production obtained by the method according to any one of claims 1 - 6 as a raw material to synthesize hydrogen chloride, reacting the hydrogen chloride with silicon powder to synthesize trichlorosilane, reducing trichlorosilane to obtain polysilicon.

9. A hydrogen purification system for polysilicon production, characterized in that, it comprises a scrubbing tower (2), a flash tank (10), a pressurizer (11) and a condenser (6), the lower part of the scrubbing tower (2) is used to store boiling trichlorosilane and is provided with an inlet pipe for introducing the hydrogen for polysilicon production into the boiling trichlorosilane so that the internal water reacts with trichlorosilane; the upper part of the scrubbing tower (2) is provided with a spraying structure (21) for atomizing and spraying trichlorosilane. The gas phase escaping from the boiling trichlorosilane contacts the atomized trichlorosilane so that the remaining water in the escaping gas phase reacts with trichlorosilane to obtain a dehydrated gas phase; The condenser (6) is connected to the first gas guide pipe (4) at the top of the scrubbing tower (2) and is used for condensing the water-removed gas phase to liquefy the vaporized trichlorosilane therein, so as to obtain hydrogen gas for polysilicon production with impurities removed. A first discharge pipe (5) is provided between the flash tank (10) and the scrubbing tower (2). A second opening and closing valve is provided on the first discharge pipe (5). The flash tank (10) is used to receive the trichlorosilane containing solid phase sent from the scrubbing tower (2) through the first discharge pipe (5) and perform flashing on it to obtain trichlorosilane vapor. The pressurizer (11) is respectively connected to the outlet of the flash tank (10) and the inlet of the scrubbing tower (2), and is used to receive the trichlorosilane vapor sent from the flash tank (10), pressurize and liquefy it, and then send it back into the scrubbing tower (2).

10. The hydrogen gas impurity removal system for polysilicon production according to claim 9, characterized in that A reflux pipe (7) is provided between the condenser (6) and the spraying structure (21) and is used to introduce the liquefied trichlorosilane into the spraying structure (21).

11. The hydrogen gas impurity removal system for polysilicon production according to claim 9, characterized in that It further includes a catalytic reactor (9), The outlet of the catalytic reactor (9) is connected to the inlet pipe of the scrubbing tower (2) and is used to catalytically oxidize the hydrogen gas for polysilicon production before it enters the scrubbing tower (2) so that the oxygen therein is converted into water.

12. The hydrogen gas impurity removal system for polysilicon production according to any one of claims 9 - 11, characterized in that A reboiler (3) is provided at the lower part of the scrubbing tower (2) and is used to heat the trichlorosilane at the lower part of the scrubbing tower (2) to a temperature above its boiling point.

13. A polysilicon production system includes a reduction furnace and a material supply unit, characterized in that The material supply unit includes the hydrogen gas impurity removal system for polysilicon production according to any one of claims 9 - 12.

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