Device for one-way preparation of electronic-grade silane gas in particle silicon manufacturing process

Abstract

The utility model discloses a device for one-way preparation of electronic grade silane gas in a particle silicon process, the device comprises a preheater, a light component removal unit, a silane reaction unit, a condensation unit, a separation unit and a gasification purification unit which are connected in sequence, and the silane reaction unit comprises more than two silane reaction towers which are arranged in parallel. According to the utility model, more than two silane reaction towers are arranged in the silane reaction unit in parallel, so that trichlorosilane is converted into silane at one time after being sequentially subjected to the steps of preheating, light component removal, reactive distillation, condensation heat exchange, separation and gasification purification; the conversion per pass can be improved, the material condensation and reboiling processes are reduced, the energy consumption is reduced, and the production process cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of silane production, in particular to a device for preparing electronic-grade silane gas in a single pass in a granular silicon production process. Background Art

[0002] Granular silicon is a type of polycrystalline silicon produced by chemical vapor deposition (CVD) in a fluidized bed, with an average particle size of approximately 1-2 mm. Granular silicon has a long history of research and development, with researchers proposing the principle of chemical vapor deposition for producing polycrystalline silicon as early as the 1950s. This process has been continuously refined. The key process flow is as follows: High-purity silicon seed crystals are added to the top of the fluidized bed reactor, where they accumulate to form a bed of seed crystal particles. After the bed is heated to the required reaction temperature, silane gas (reaction gas) and hydrogen gas (carrier gas) are introduced from the bottom of the reactor. This mixture fluidizes the seed crystal bed. As the preheated gas mixture passes through the heated bed, silane decomposes to form elemental silicon, which is deposited on the surface of the silicon seed crystals. The reaction temperature for silane gas pyrolysis in the fluidized bed is 500°C to 800°C. The characteristics of the fluidized bed process bring multiple advantages to the production of granular silicon. For example, the temperature distribution in the silane fluidized bed is relatively uniform, the surface area of silicon deposition in the reactor is large, the deposition rate is fast, and continuous feeding and discharging can be achieved.

[0003] The granular silicon process requires the key intermediate product silane gas. The industrial production methods of silane gas are generally divided into three categories, namely the silicon-magnesium alloy method, the sodium aluminum hydride method and the trichlorosilane disproportionation method.

[0004] The silicon-magnesium alloy method uses a chemical reaction between magnesium silicide powder and ammonium chloride in a liquid ammonia environment to produce silane gas. It is the world's earliest industrialized silane gas production technology and one of the more mature production technologies in China. Its chemical reaction equation is: Mg2Si+NH4CL→MgCL2·6NH3+SiH4

[0005] The production method comprises magnesium silicide synthesis, silane synthesis, molecular sieve adsorption, ammonia tail gas absorption, etc.; the reaction raw materials are mainly silicon powder, magnesium powder, ammonium chloride, ammonia water, etc., which are easily available on the market.

[0006] The typical representative of the sodium aluminum hydride process is MEMC in the United States. Silane gas is synthesized by reacting sodium aluminum hydride with silicon tetrafluoride gas. The chemical reaction equation is:

[0007] SiO2+CaF2+H2SO4→H2SiF6+CaSO4+2H2O

[0008] H2SiF6→SiF4+HF

[0009] Na+Al+2H2→NaAlH4

[0010] NaAlH4+SiF4→SiH4+NaAlF4

[0011] The crude silane gas produced by the reaction is purified and refined in an adsorption tower, a heavy removal tower, and a light removal tower, raising the purity of the crude silane gas to above 6N, a high-purity electronic-grade silane gas. The resulting liquid silane is then stored in a product silane storage tank. The evaporation of the liquid silane gas returns it to room-temperature silane gas for use in the silane reduction polysilicon process. Sodium fluorosilicate, a byproduct of fertilizer production, can be used as a raw material for the production of silicon tetrafluoride. This raw material is readily available even when using the fluorite-sulfuric acid method.

[0012] The by-product, sodium aluminum fluoride, can be used as a raw material for electrolytic aluminum (instead of cryolite) and can be sold to the sulfate industry. In the liquid phase reaction, the HF product of the pyrolysis of fluorosilicic acid is not discharged into the system, but is returned to the first reactor as a fluorine source. The American MEMC company used this process for a scale of more than 1,000 tons 20 years ago, and its technical route is relatively early.

[0013] The chlorosilane disproportionation process was developed by Union Carbide Corporation (UCC). The process involves hydrogenating silicon tetrachloride to produce trichlorosilane, which is then disproportionated to produce dichlorosilane. Dichlorosilane is then disproportionated again to produce silane gas. The reaction equation is:

[0014] SiCl4+H2+Si→SiHCl3

[0015] SiHCl3→SiH2Cl2+SiCl4

[0016] SiH2Cl2→SiHCl3+SiH4

[0017] The process involves three elements, the reaction mechanism is cyclic, the process flow is simple, and it is suitable for large-scale production.

[0018] However, all three of the above-mentioned process methods have certain defects. For example, due to the high cost of the silicon-magnesium alloy method, the production process has not yet developed a production scale of 100 tons, and it is unrealistic to promote industrial production. At the same time, the raw materials introduce a large number of impurity elements, and electronic-grade silane gas products cannot be produced; the sodium aluminum hydride method has a long reaction chain, a complex process, and many impurity elements. The intermediate pyrolysis product HF is a colorless, pungent toxic gas under normal conditions, which is contrary to the modern development of environmentally harmless chemistry, environmentally friendly chemistry, and clean chemistry, that is, reducing or eliminating the use of hazardous substances and the design concept of chemicals and processes, and has gradually withdrawn from the mainstream process route; the chlorosilane disproportionation process has a low single-pass conversion rate of only 8% to 10%, and requires repeated reflux to improve the conversion rate. A large amount of energy is wasted in the continuous condensation and reboiling process of the material, resulting in high production costs and contrary to the modern development of clean chemistry and environmentally friendly chemistry concepts.

[0019] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Utility Model Content

[0020] Purpose of the utility model: The technical problem to be solved by the utility model is to address the deficiencies of the existing technology and provide a device for preparing electronic-grade silane gas in a single pass in the granular silicon process, which can improve the single-pass conversion rate, while reducing the material condensation and reboiling process, reducing energy consumption, and reducing the production process cost.

[0021] In order to solve the above technical problems, the utility model discloses a device for preparing electronic-grade silane gas in a single pass in a granular silicon process, which includes a preheater, a light removal unit, a silane reaction unit, a condensation unit, a separation unit and a gasification purification unit connected in sequence, wherein the silane reaction unit includes two or more silane reaction towers arranged in parallel.

[0022] The utility model arranges two or more silane reaction towers in parallel in a silane reaction unit, so that trichlorosilane is converted into silane at one time after sequentially undergoing the steps of preheating, light removal, reactive distillation, condensation heat exchange, separation, and gasification purification. Compared with other processes in which the product is refluxed and the steps are repeated multiple times to achieve a high conversion rate, the utility model can improve the single-pass conversion rate, and at the same time reduce the material condensation and reboiling processes, reduce energy consumption, and reduce the production process cost.

[0023] In some examples, the light-removal unit includes a light-removal tower, a light-removal tower top condensing unit, a light-removal tower reboiler and a chlorosilane buffer tank, the preheater outlet is connected to the feed plate of the light-removal tower, the top outlet of the light-removal tower is connected to the air inlet of the light-removal tower top condensing unit, the stuffing box area of the silane reaction tower, the shell side inlet of the light-removal tower reboiler and the inlet of the chlorosilane buffer tank are respectively connected to the bottom material outlet of the light-removal tower, the shell side outlet of the light-removal tower reboiler is connected to the lower part of the light-removal tower; the condensate outlet of the light-removal tower top condensing unit is connected to the top reflux port of the light-removal tower through a liquid seal pipeline.

[0024] In some examples, the delightening tower top condensing unit includes a delightening tower condenser and a tail gas condenser, and the air outlet of the delightening tower condenser is connected to the air inlet of the tail gas condenser; the air inlet of the delightening tower top condensing unit is the air inlet of the delightening tower condenser, and the condensate outlet of the delightening tower top condensing unit includes the condensate outlet of the delightening tower condenser and the condensate outlet of the tail gas condenser.

[0025] In some examples, the condensing unit includes a tower top condenser, a boron-phosphorus adsorption tank, a material cryogenic refrigerator, a reflux pump, a silane reaction tower reflux tank, a three-stage cryogenic refrigerator, a four-stage cryogenic refrigerator, a five-stage cryogenic refrigerator, a six-stage cryogenic refrigerator, a silane phase separation tank, and a silane booster pump. The tower top outlet of the silane reaction tower is connected to the air inlet of the tower top condenser, the condensate outlet of the tower top condenser is connected to the inlet of the silane reaction tower reflux tank, the outlet of the silane reaction tower reflux tank is connected to the inlet of the reflux pump, and the tower top reflux port of at least one silane reaction tower among the two or more silane reaction towers is connected to the outlet of the reflux pump; the tower top condenser The air outlet of the device is connected to the shell-side air inlet of the material cryogenic refrigerator through the boron-phosphorus adsorption tank, the air outlet of the material cryogenic refrigerator is connected to the air inlet of the three-stage cryogenic refrigerator, the air outlet of the three-stage cryogenic refrigerator is connected to the air inlet of the four-stage cryogenic refrigerator, the air outlet of the four-stage cryogenic refrigerator is connected to the air inlet of the five-stage cryogenic refrigerator, the condensate outlet of the five-stage cryogenic refrigerator is connected to the tube-side inlet of the six-stage cryogenic refrigerator, and the tube-side outlet of the six-stage cryogenic refrigerator is connected to the inlet of the silane phase-separation tank; the condensate outlet of the silane phase-separation tank is connected to the inlet of the silane booster pump, and the outlet of the silane booster pump is connected to the shell-side inlet of the five-stage cryogenic refrigerator.

[0026] In some examples, the condensate outlet of the material cryogenic refrigerator, the condensate outlet of the third-stage cryogenic refrigerator, and the condensate outlet of the fourth-stage cryogenic refrigerator are connected in parallel to the middle and lower parts of each of the silane reaction towers.

[0027] In some examples, the separation unit includes a silane separation tower, a silane separation tower reboiler, a silane separation tower condenser and a silane buffer tank, the liquid inlet of the silane separation tower is connected to the shell outlet of the five-stage cryogenic refrigerator, the kettle outlet of the silane separation tower is respectively connected to the liquid inlet of the silane buffer tank, the inlet of the silane separation tower reboiler and the middle and lower parts of each of the silane reaction towers through corresponding pipelines; the outlet of the silane separation tower reboiler is connected to the middle and lower parts of the silane separation tower; the air inlet of the silane separation tower condenser is connected to the top air outlet of the silane separation tower, and the condensate outlet of the silane separation tower condenser is connected to the top reflux port of the silane separation tower.

[0028] In some examples, the gasification purification unit includes a silane vaporization tower, a silane vaporization tower condenser, a silane vaporization tower reboiler, a product pipeline, a difluorochloromethane buffer tank and a difluorochloromethane booster pump, the silane liquid inlet of the silane vaporization tower is connected to the middle tower outlet of the silane separation tower, the top gas outlet of the silane vaporization tower is connected to the gas inlet of the silane vaporization tower condenser, and the condensate outlet of the silane vaporization tower condenser is connected to the top tower reflux port of the silane vaporization tower; the middle and upper outlet of the silane vaporization tower is connected to the shell side inlet of the material cryogenic refrigerator, and the shell side outlet of the material cryogenic refrigerator is connected to the product pipeline; the shell side inlet of the silane vaporization tower reboiler is connected to the outlet of the difluorochloromethane booster pump, the shell side outlet of the silane vaporization tower reboiler is connected to the inlet of the difluorochloromethane buffer tank, and the outlet of the difluorochloromethane buffer tank is connected to the inlet of the difluorochloromethane booster pump.

[0029] In some examples, the device also includes a silane impurity vent line, a buffer tank tail gas cryogenic refrigerator, and a silane gas phase vent line, the gas outlet of the silane separation tower condenser, the gas outlet of the silane vaporization tower condenser, and the gas outlet of the six-stage cryogenic refrigerator are connected in parallel to the silane impurity vent line; the air inlet of the buffer tank tail gas cryogenic refrigerator is connected to the gas outlet of the silane buffer tank, and the gas outlet of the buffer tank tail gas cryogenic refrigerator is connected to the silane gas phase vent line.

[0030] In some examples, the device includes a first pipeline for connecting the stuffing box area of the silane reaction tower and the bottom material outlet of the light removal tower, and the first pipeline is provided with a trichlorosilane pressure pump.

[0031] In some examples, the apparatus further includes a feed line for feeding mixed trichlorosilane raw material, wherein the feed line is connected to the preheater inlet.

[0032] Beneficial effects:

[0033] 1) The chlorosilane disproportionation method is upgraded and reconstructed. Compared with the prior art which adopts a single silane reaction tower, the utility model adopts a silane reaction unit with multiple silane reaction towers arranged in parallel, which can improve the single-pass conversion rate, reduce the material condensation and reboiling process, reduce energy consumption, and reduce the cost of the production process; and can produce a variety of silicon source materials such as silane gas, silicon tetrachloride, and dichlorodihydrogen silicon, and can arbitrarily match the product ratio; various reaction products and silane gas are easily separated, and high-purity silane gas of 99.99999999~99.9999999999 (9~11N) can be obtained; high energy consumption is changed to low energy consumption, high cost is changed to low cost, single product is changed to multiple products, and low quality is changed to high quality. Various upgrades and changes make up for and improve product competitiveness.

[0034] 2) The method of efficiently preparing electronic-grade silane gas in a single pass in the granular silicon process is consistent with the modern development of environmentally sound chemistry, environmentally friendly chemistry, and clean chemistry, that is, the design concept of reducing or eliminating the use of hazardous substances and the production of chemicals and processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0036] Figure 1 The present invention is a schematic structural diagram of an apparatus for preparing electronic-grade silane gas in a single pass in a granular silicon production process disclosed in one embodiment of the present invention.

[0037] Description of the accompanying drawings:

[0038] 1. Preheater; 2. Lightness Removal Column; 3. Lightness Removal Column Condenser; 4. Tail Gas Condenser; 5. Lightness Removal Column Reboiler; 6. Trichlorosilane Pressure Pump; 7. Silane Reaction Column; 7-1. First Silane Reaction Column; 7-2. Second Silane Reaction Column; 7-3. Third Silane Reaction Column; 7-4. Fourth Silane Reaction Column; 8. Reboiler; 8-1. First Reboiler; 8-2. Second Reboiler; 8-3. Third Reboiler; 8-4. Fourth Reboiler; 15. Top Condenser; 16. Boron-Phosphorus Adsorption Tank; 17. Material Cryogenic Cooler; 18. Reflux Pump; 19. Third-Stage Cryogenic Cooler; 20. Fourth-Stage Cryogenic Cooler; 21. Fifth-Stage Cryogenic Cooler; 22. Sixth-Stage Cryogenic Cooler 23. Silane phase separation tank; 24. Silane booster pump; 25. Silane separation tower; 26. Silane separation tower reboiler; 27. Silane separation tower condenser; 28. Silane vaporization tower; 29. Silane vaporization tower condenser; 30. Silane vaporization tower reboiler; 31. Difluorochloromethane buffer tank; 32. Difluorochloromethane booster pump; 34. Silane buffer tank; 33. Chlorosilane buffer tank; 35. Buffer tank tail gas deep cooler; 36. Silane reaction tower reflux tank; 1-1 feed pipeline; 1-2. light component vent pipeline; 1-3. product pipeline; 1-4. silane impurity vent pipeline; 1-5 liquid silane product pipeline; 1-6. silane gas phase vent pipeline. DETAILED DESCRIPTION

[0039] The utility model discloses a device for preparing electronic-grade silane gas in a single pass in a granular silicon production process, which comprises a preheater 1, a light removal unit, a silane reaction unit, a condensation unit, a separation unit and a gasification purification unit connected in sequence, wherein the silane reaction unit comprises two or more silane reaction towers 7 arranged in parallel.

[0040] The utility model arranges two or more silane reaction towers 7 in parallel in a silane reaction unit, so that trichlorosilane is converted into silane in one go after sequentially undergoing the steps of preheating, light removal, reactive distillation, condensation heat exchange, separation, and gasification purification. Compared with other processes in which the product is refluxed and the steps are repeated multiple times to achieve a high conversion rate, the utility model can improve the single-pass conversion rate, while reducing the material condensation and reboiling processes, reducing energy consumption, and reducing the production process cost.

[0041] In one example, see Figure 1 The silane reaction unit includes four silane reaction towers arranged in parallel, and a reboiler 8 is provided at the bottom of each silane reaction tower. Figure 1The four silane reaction towers are respectively a first silane reaction tower 7-1, a second silane reaction tower 7-2, a third silane reaction tower 7-3, and a fourth silane reaction tower 7-4. A first reboiler 8-1 is provided at the bottom of the first silane reaction tower 7-1, a second reboiler 8-2 is provided at the bottom of the second silane reaction tower 7-2, a third reboiler 8-3 is provided at the bottom of the third silane reaction tower 7-3, and a fourth reboiler 8-4 is provided at the bottom of the fourth silane reaction tower 7-4.

[0042] For some examples, see Figure 1 The light-removal unit includes a light-removal tower 2, a light-removal tower top condensing unit, a light-removal tower reboiler 5, and a chlorosilane buffer tank 33. The outlet of the preheater 1 is connected to the feed plate of the light-removal tower 2, the top outlet of the light-removal tower 2 is connected to the air inlet of the light-removal tower top condensing unit, the stuffing box area of the silane reaction tower 7, the shell-side inlet of the light-removal tower reboiler 5, and the inlet of the chlorosilane buffer tank 33 are respectively connected to the bottom material outlet of the light-removal tower 2, and the shell-side outlet of the light-removal tower reboiler 5 is connected to the lower part of the light-removal tower 2. The condensate outlet of the light-removal tower top condensing unit is connected to the top reflux port of the light-removal tower 2 through a liquid seal pipeline.

[0043] For some examples, see Figure 1 The delight tower top condensing unit includes a delight tower condenser 3 and a tail gas condenser 4, and the air outlet of the delight tower condenser 3 is connected to the air inlet of the tail gas condenser 4. The air inlet of the delight tower top condensing unit is the air inlet of the delight tower condenser 3, and the condensate outlet of the delight tower top condensing unit includes the condensate outlet of the delight tower condenser 3 and the condensate outlet of the tail gas condenser 4. The vent of the tail gas condenser 4 is connected to the light component vent pipeline 1-2.

[0044] For some examples, see Figure 1The condensing unit includes a top condenser 15, a boron-phosphorus adsorption tank 16, a material cryogenic refrigerator 17, a reflux pump 18, a silane reaction tower reflux tank 36, a third-stage cryogenic refrigerator 19, a fourth-stage cryogenic refrigerator 20, a fifth-stage cryogenic refrigerator 21, a sixth-stage cryogenic refrigerator 22, a silane phase separation tank 23 and a silane booster pump 24. The top outlet of the silane reaction tower 7 is connected to the air inlet of the top condenser 15, the condensate outlet of the top condenser 15 is connected to the inlet of the silane reaction tower reflux tank 36, the outlet of the silane reaction tower reflux tank 36 is connected to the inlet of the reflux pump 18, and the top reflux port of at least one of the two or more silane reaction towers 7 is connected to the outlet of the reflux pump 18. The air outlet of the top condenser 15 is connected to the shell-side air inlet of the material cryogenic refrigerator 17 through the boron-phosphorus adsorption tank 16. The air outlet of the material cryogenic refrigerator 17 is connected to the air inlet of the third-stage cryogenic refrigerator 19. The air outlet of the third-stage cryogenic refrigerator 19 is connected to the air inlet of the fourth-stage cryogenic refrigerator 20. The air outlet of the fourth-stage cryogenic refrigerator 20 is connected to the air inlet of the fifth-stage cryogenic refrigerator 21. The condensate outlet of the fifth-stage cryogenic refrigerator 21 is connected to the tube-side inlet of the sixth-stage cryogenic refrigerator 22. The tube-side outlet of the sixth-stage cryogenic refrigerator 22 is connected to the inlet of the silane phase-separation tank 23. The condensate outlet of the silane phase-separation tank 23 is connected to the inlet of the silane booster pump 24. The outlet of the silane booster pump 24 is connected to the shell-side inlet of the fifth-stage cryogenic refrigerator 21.

[0045] For some examples, see Figure 1 The condensate outlet of the material cryogenic cooler 17 , the condensate outlet of the third-stage cryogenic cooler 19 and the condensate outlet of the fourth-stage cryogenic cooler 20 are connected in parallel to the middle and lower parts of each silane reaction tower 7 .

[0046] For some examples, see Figure 1 The separation unit includes a silane separation tower 25, a silane separation tower reboiler 26, a silane separation tower condenser 27 and a silane buffer tank 34. The silane buffer tank 34 is used to store liquid silane products. The liquid inlet of the silane separation tower 25 is connected to the shell outlet of the five-stage cryogenic refrigerator 21, and the kettle outlet of the silane separation tower 25 is connected to the liquid inlet of the silane buffer tank 34, the inlet of the silane separation tower reboiler 26 and the middle and lower parts of each silane reaction tower 7 through corresponding pipelines. The outlet of the silane separation tower reboiler 26 is connected to the middle and lower part of the silane separation tower 25. The air inlet of the silane separation tower condenser 27 is connected to the top air outlet of the silane separation tower 25, and the condensate outlet of the silane separation tower condenser 27 is connected to the top reflux port of the silane separation tower 25. The liquid outlet of the silane buffer tank 34 is connected to the liquid silane product pipeline 1-5.

[0047] For some examples, see Figure 1The gasification and purification unit includes a silane vaporizer 28, a silane vaporizer condenser 29, a silane vaporizer reboiler 30, product pipelines 1-3, a difluorochloromethane buffer tank 31, and a difluorochloromethane booster pump 32. The silane inlet of the silane vaporizer 28 is connected to the middle outlet of the silane separation tower 25. The top outlet of the silane vaporizer 28 is connected to the air inlet of the silane vaporizer condenser 29. The condensate outlet of the silane vaporizer condenser 29 is connected to the top reflux port of the silane vaporizer 28. The upper and middle outlet of the silane vaporizer 28 is connected to the shell-side inlet of the material cryogenic refrigerator 17. The shell-side outlet of the material cryogenic refrigerator 17 is connected to the product pipeline 1-3. The kettle outlet of the silane vaporizer 28 is connected to the tube-side inlet of the silane vaporizer reboiler 30, and the tube-side outlet of the silane vaporizer reboiler 30 is connected to the middle and lower portion of the silane vaporizer 28. The kettle outlet of the silane vaporizer 28 is connected to the tube-side inlet of the silane vaporizer reboiler 30, and the tube-side outlet of the silane vaporizer reboiler 30 is connected to the middle and lower portion of the silane vaporizer 28. The shell-side inlet of the silane vaporizer reboiler 30 is connected to the outlet of a difluorochloromethane booster pump 32, and the shell-side outlet of the silane vaporizer reboiler 30 is connected to the inlet of a difluorochloromethane buffer tank 31, and the outlet of the difluorochloromethane buffer tank 31 is connected to the inlet of the difluorochloromethane booster pump 32.

[0048] For some examples, see Figure 1 The device also includes a silane impurity vent line 1-4, a buffer tank tail gas cryocooler 35, and a silane vapor phase vent line 1-6. The outlet of the silane separation tower condenser 27, the outlet of the silane vaporization tower condenser 29, and the outlet of the six-stage cryocooler 22 are connected in parallel to the silane impurity vent line 1-4. The air inlet of the buffer tank tail gas cryocooler 35 is connected to the air outlet of the silane buffer tank 34, and the air outlet of the buffer tank tail gas cryocooler 35 is connected to the silane vapor phase vent line 1-6.

[0049] For some examples, see Figure 1 The device includes a first pipeline for connecting the stuffing box area of the silane reaction tower 7 with the bottom material outlet of the light removal tower 2, and the first pipeline is provided with a trichlorosilane pressure pump 6.

[0050] For some examples, see Figure 1 The device also includes a feed pipeline 1-1 for feeding mixed trichlorosilane raw materials, and the feed pipeline 1-1 is connected to the inlet of the preheater 1.

[0051] For some examples, see Figure 1, the heat of preheater 1 comes from the chlorosilane liquid in chlorosilane buffer tank 33. Specifically, chlorosilane buffer tank 33 is a pressurized chlorosilane buffer tank, and the shell-side inlet of preheater 1 is connected with a liquid inlet pipe, the end of which is inserted below the liquid level in the tank of chlorosilane buffer tank 33, and the shell-side outlet of preheater 1 is connected to chlorosilane buffer tank 33 through a corresponding pipeline. Chlorosilane liquid is pressed into the shell side of preheater 1 through the liquid inlet pipe by pressure, and the mixed chlorosilane raw material passes through the tube side of preheater 1 through 1-1 feed pipeline. The two exchange heat in preheater 1 to achieve preheating and temperature increase of the mixed chlorosilane raw material. The chlorosilane liquid after heat exchange flows out from the shell-side outlet of preheater 1 and flows back to chlorosilane buffer tank 33 through the corresponding pipeline.

[0052] Hereinafter, the process of preparing electronic-grade silane gas in the apparatus for preparing electronic-grade silane gas in a single pass in the granular silicon production process disclosed in the present invention will be described in conjunction with the accompanying drawings.

[0053] The upstream trichlorosilane mixture is prepared to supply mixed chlorosilane, the main components of which include trichlorosilane, dichlorodihydrosilane and a small amount of hydrogen, which enter the preheater 1 together and are preheated to a temperature of 70-75°C.

[0054] The preheated mixed chlorosilane raw material enters the tower through the feed plate of the light component removal tower 2, and mass and heat are transferred in the tower. The light component carries heat and rises in the form of gas. During the rising process, it contacts the descending heavy component liquid. After condensation, it descends through the downcomer. The light component contained in the heavy component naturally descends through the downcomer due to gravity. During the descending process, it absorbs the heat of the rising light component and becomes the light component that continues to rise in the gaseous state. During the process of the light component rising and the heavy component descending, mass and heat transfer are also carried out synchronously. Finally, some light components in trichlorosilane TCS rise to the top of the tower and some heavy components descend to the bottom of the tower, achieving the purpose of light component removal and separation. The top outlet of the light-removal tower 2 finally extracts the hydrogen, nitrogen, dichlorosilane, and trichlorosilane components contained in the mixed chlorosilane raw material. The top outlet of the light-removal tower 2 is condensed in turn through the light-removal tower condenser 3 and the tail gas condenser 4 located at the top of the light-removal tower 2. The condensed liquid is refluxed to the top reflux port of the light-removal tower 2 through the liquid seal pipeline, and the mass transfer and heat transfer are circulated again to continuously cycle the process. The bottom material outlet of the light-removal tower 2 extracts mixed chlorosilane, the main components of which are trichlorosilane and dichlorosilane. The bottom material of the light-removal tower 2 is divided into three streams, one of which is reboiled and heated by the light-removal tower reboiler 5. The material that has gained heat enters the lower part of the light-removal tower 2 to replenish the heat lost in the tower. One stream is discharged to the chlorosilane buffer tank 33 to adjust the liquid level in the light-removal tower 2. The last stream is pressurized by the trichlorosilane pressure pump 6 and sent to the stuffing box area of the silane reaction tower 7 for reaction.

[0055] In this example, the bottom temperature of the light-removal tower 2 is 65-66°C, and the top temperature is 63-64°C.

[0056] In this example, the condensation temperature of the lightness removal tower condenser 3 and the condensation temperature of the tail gas condenser 4 are in the range of 28 to 29°C.

[0057] Afterwards, the bottom material of the lightness removal tower 2 is pressurized by the trichlorosilane pressure pump 6 and transported to the silane reaction tower 7 for catalytic disproportionation reaction. The specific process is as follows: after being pressurized, the bottom material of the lightness removal tower 2 passes through the feed plate and enters the stuffing box area of the silane reaction tower 7. In the stuffing box area, the first disproportionation reaction occurs under the action of the catalyst to produce dichlorosilane and silicon tetrachloride:

[0058] SiHCl3(l)→SiH2Cl2(g)↑+SiCl4(l)

[0059] Dichlorosilane rises in the high temperature of the silane reaction tower at a top temperature of 60-70°C. It undergoes a second disproportionation reaction under the action of a catalyst in the stuffing box area to produce silane and trichlorosilane:

[0060] SiH2Cl2(g)→SiHCl3(g)+SiH4(g)↑

[0061] Silane, dichlorosilane, and some trichlorosilane are extracted from the top outlet of the silane reaction tower 7. The top outlet of the silane reaction tower 7 is condensed by the overhead condenser 15 to obtain a condensed liquid mixture and uncondensed gas. The main components of the condensed liquid mixture include trichlorosilane and dichlorosilane, and the uncondensed gas is mainly silane. The condensed liquid mixture is temporarily stored in the silane reaction tower reflux tank 36. The silane reaction tower reflux tank 36 is in a gas phase equilibrium state, with the top containing a gas phase mixture whose main components are silane and the bottom containing a liquid phase mixture whose main components are trichlorosilane and dichlorosilane. The liquid phase mixture is pressurized by the reflux pump 18 and refluxed to the top of the silane reaction tower 7 for reuse. The uncondensed gas phase is adsorbed by the boron-phosphorus adsorption tank 16 and then enters the shell-side air inlet of the material cryogenic refrigerator 17.

[0062] More specifically, the liquid mixture refluxes to the top of silane reactor 7 for reuse as it flows downward under gravity within the packing box region of silane reactor 7. After encountering the rising gaseous dichlorosilane, it undergoes heat exchange. After this heat exchange, trichlorosilane undergoes a subsequent disproportionation reaction. This process simultaneously involves heat exchange, disproportionation reaction, and rectification. The first and second disproportionation reactions continue in the packing box region, and this cycle repeats until both the mid- and top-of-the-tower temperatures of silane reactor 7 stabilize. In this example, the top temperature of silane reactor 7 is controlled at 60-64°C, while the mid-tower temperature is stabilized at 82-85°C, achieving dynamic equilibrium.

[0063] Afterwards, the uncondensed gas phase from the top condenser 15 enters the boron-phosphorus adsorption tank 16, the main function of which is to adsorb the boron and phosphorus elements in the uncondensed gas phase. The uncondensed gas phase after adsorption enters the shell side of the material cryogenic refrigerator 17 for re-condensation. The condensed liquid material is refluxed to the middle and lower part of the silane reaction tower 7. The temperature of the condensed liquid material is -7.8℃~-8.8℃. It enters the middle and lower part and flows to the tower bottom. The tower bottom liquid is reboiled in the reboiler 8 of the silane reaction tower 7 to provide heat lost in the tower. After accumulation, the amount of silicon tetrachloride in the tower bottom gradually increases, and the excess silicon tetrachloride is discharged to the chlorosilane buffer tank 33 through the tower bottom. The uncondensed gas phase of the material cryogenic refrigerator 17 flows out from the air outlet of the material cryogenic refrigerator 17 and enters the air inlet of the tertiary cryogenic refrigerator 19. The uncondensed gas phase of the third-stage cryogenic refrigerator 19 flows out from the air outlet of the third-stage cryogenic refrigerator 19 and enters the air inlet of the fourth-stage cryogenic refrigerator 20, and the condensed liquids from the fourth-stage cryogenic refrigerator 20, the third-stage cryogenic refrigerator 19 and the material cryogenic refrigerator 17 all flow back to the middle and lower part of the silane reaction tower 7. The uncondensed gas phase of the fourth-stage cryogenic refrigerator 20 flows out from the air outlet of the fourth-stage cryogenic refrigerator 20 and enters the air inlet of the fifth-stage cryogenic refrigerator 21. After condensation in the fifth-stage cryogenic refrigerator 21, 99% of the gas phase is condensed into liquid and flows out from the condensate outlet of the fifth-stage cryogenic refrigerator 21 again, entering the pipe inlet of the sixth-stage cryogenic refrigerator 22. After condensation in the sixth-stage cryogenic refrigerator 22, 99% of the gas phase is condensed into liquid and enters the silane phase separation tank 23. When the silane liquid accumulates to a specified level, it is pressurized by the silane booster pump 24 and delivered to the shell-side inlet of the five-stage cryocooler 21. After exchanging cooling energy, it flows out of the shell-side outlet of the five-stage cryocooler 21 in liquid form and enters the liquid inlet of the silane separation tower 25. When the liquid level in the silane separation tower 25 reaches the specified level and fills the silane separation tower reboiler 26, the liquid silane is reboiled in the silane separation tower reboiler 26 and then enters the silane separation tower 25 in a vapor phase. The gaseous silane rising in the silane separation tower 25 contacts and exchanges heat with the liquid silane returned from the shell outlet of the five-stage cryogenic refrigerator 21. 0.00000001% to 0.01% of light impurities in the liquid silane rise to the top of the tower and are extracted. The gaseous silane mixed with the light impurities enters the silane separation tower condenser 27. More than 99% of the silane is refluxed to the silane separation tower 25 in liquid form. The 0.00000001% to 0.01% of light impurities that have not been condensed are The impurities are discharged through the gas outlet of the silane separation tower condenser 27, and the liquid silane and heavy component impurities in the bottom of the silane separation tower 25 are withdrawn from the bottom of the tower and refluxed to the middle and lower part of the silane reaction tower 7 to participate in the reaction and separation process again. The silane separation tower 25 is withdrawn from the middle part of the tower and sent to the silane vaporization tower 28 through the connecting pipe. The liquid phase in the bottom of the silane vaporization tower 28 is reboiled through the silane vaporization tower reboiler 30 tube pass and then enters the silane vaporization tower 28 as a gas phase to provide heat exchange. The rising silane gas and

[0064] 0.000000001% to 0.001% light component impurities are condensed in the silane vaporization tower condenser 29 and then refluxed to the silane vaporization tower 28. 0.000000001% to 0.001% light component impurities are discharged through the vent pipe of the silane vaporization tower condenser 29. The liquid silane and heavy component impurities in the bottom of the silane vaporization tower 28 are refluxed to the middle and lower part of the silane reaction tower 7 through the bottom outlet to participate in the reaction and separation process again. The excess silane liquid in the bottom of the silane separation tower 25 and the bottom of the silane vaporization tower 28 after distribution enters the silane buffer tank 34 for buffering. The silane liquid extracted from the middle part of the silane vaporization tower 28 is exchanged for cooling capacity through the material deep freezer 17 pipe line and then sent out as a product through the product pipeline 1-3.

[0065] The gas phase from the silane buffer tank 34 is cryogenically cooled in the buffer tank tail gas cryocooler 35 and then discharged. The refrigerant in the shell side of the silane vaporizer reboiler 30 is difluorochloromethane. This difluorochloromethane is buffered in the difluorochloromethane buffer tank 31 and pressurized by the difluorochloromethane booster pump 32 before being supplied to the shell side of the silane vaporizer reboiler 30 to provide cooling capacity.

[0066] This utility model provides a concept and method for a single-pass device for producing electronic-grade silane gas in a granular silicon production process. There are many methods and approaches for implementing this technical solution. The above is only a preferred embodiment of the utility model. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the utility model, and such improvements and modifications should also be considered within the scope of protection of the utility model. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. A device for preparing electronic grade silane gas in a single pass in a granular silicon production process, characterized in that: The invention comprises a preheater (1), a light removal unit, a silane reaction unit, a condensation unit, a separation unit and a gasification purification unit which are connected in sequence, wherein the silane reaction unit comprises two or more silane reaction towers (7) arranged in parallel.

2. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 1, characterized in that: The light removal unit comprises a light removal tower (2), a light removal tower top condensing unit, a light removal tower reboiler (5) and a chlorosilane buffer tank (33); the outlet of the preheater (1) is connected to the feed plate of the light removal tower (2); the top outlet of the light removal tower (2) is connected to the air inlet of the light removal tower top condensing unit; the stuffing box area of the silane reaction tower (7), the shell side inlet of the light removal tower reboiler (5) and the inlet of the chlorosilane buffer tank (33) are respectively connected to the bottom material outlet of the light removal tower (2); the shell side outlet of the light removal tower reboiler (5) is connected to the lower part of the light removal tower (2); the condensate outlet of the light removal tower top condensing unit is connected to the top reflux port of the light removal tower (2) through a liquid seal pipeline.

3. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 2, characterized in that: The delightening tower top condensing unit comprises a delightening tower condenser (3) and a tail gas condenser (4); the air outlet of the delightening tower condenser (3) is connected to the air inlet of the tail gas condenser (4); the air inlet of the delightening tower top condensing unit is the air inlet of the delightening tower condenser (3), and the condensate outlet of the delightening tower top condensing unit comprises the condensate outlet of the delightening tower condenser (3) and the condensate outlet of the tail gas condenser (4).

4. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 3, characterized in that: The condensing unit comprises a tower top condenser (15), a boron-phosphorus adsorption tank (16), a material cryogenic refrigerator (17), a reflux pump (18), a silane reaction tower reflux tank (36), a third-stage cryogenic refrigerator (19), a fourth-stage cryogenic refrigerator (20), a fifth-stage cryogenic refrigerator (21), a sixth-stage cryogenic refrigerator (22), a silane phase separation tank (23) and a silane booster pump (24); the tower top outlet of the silane reaction tower (7) is connected to the air inlet of the tower top condenser (15); the condensate outlet of the tower top condenser (15) is connected to the inlet of the silane reaction tower reflux tank (36); the outlet of the silane reaction tower reflux tank (36) is connected to the inlet of the reflux pump (18); the tower top reflux port of at least one of the two or more silane reaction towers (7) is connected to the outlet of the reflux pump (18); the tower top condenser The air outlet of (15) is connected to the shell-side air inlet of the material cryogenic refrigerator (17) through the boron-phosphorus adsorption tank (16), the air outlet of the material cryogenic refrigerator (17) is connected to the air inlet of the third-stage cryogenic refrigerator (19), the air outlet of the third-stage cryogenic refrigerator (19) is connected to the air inlet of the fourth-stage cryogenic refrigerator (20), the air outlet of the fourth-stage cryogenic refrigerator (20) is connected to the air inlet of the fifth-stage cryogenic refrigerator (21), the condensate outlet of the fifth-stage cryogenic refrigerator (21) is connected to the tube-side inlet of the sixth-stage cryogenic refrigerator (22), and the tube-side outlet of the sixth-stage cryogenic refrigerator (22) is connected to the inlet of the silane phase separation tank (23); the condensate outlet of the silane phase separation tank (23) is connected to the inlet of the silane booster pump (24), and the outlet of the silane booster pump (24) is connected to the shell-side inlet of the fifth-stage cryogenic refrigerator (21).

5. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 4, characterized in that: The condensate outlet of the material cryogenic refrigerator (17), the condensate outlet of the third-stage cryogenic refrigerator (19) and the condensate outlet of the fourth-stage cryogenic refrigerator (20) are connected in parallel to the middle and lower parts of each of the silane reaction towers (7).

6. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 4, characterized in that: The separation unit comprises a silane separation tower (25), a silane separation tower reboiler (26), a silane separation tower condenser (27) and a silane buffer tank (34); the liquid inlet of the silane separation tower (25) is connected to the shell outlet of the five-stage cryogenic refrigerator (21); the bottom outlet of the silane separation tower (25) is connected to the liquid inlet of the silane buffer tank (34), the inlet of the silane separation tower reboiler (26) and the middle and lower parts of each of the silane reaction towers (7) through corresponding pipelines; the outlet of the silane separation tower reboiler (26) is connected to the middle and lower parts of the silane separation tower (25); the air inlet of the silane separation tower condenser (27) is connected to the top air outlet of the silane separation tower (25), and the condensate outlet of the silane separation tower condenser (27) is connected to the top reflux port of the silane separation tower (25).

7. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 6, characterized in that: The gasification purification unit comprises a silane vaporization tower (28), a silane vaporization tower condenser (29), a silane vaporization tower reboiler (30), a product pipeline (1-3), a difluorochloromethane buffer tank (31) and a difluorochloromethane booster pump (32); the silane liquid inlet of the silane vaporization tower (28) is connected to the tower middle outlet of the silane separation tower (25); the tower top gas outlet of the silane vaporization tower (28) is connected to the gas inlet of the silane vaporization tower condenser (29); the condensate outlet of the silane vaporization tower condenser (29) is connected to the tower top reflux port of the silane vaporization tower (28); the middle and upper outlet of the silane vaporization tower (28) is connected to the material deep cooler (17); ), the shell-side outlet of the material cryogenic cooler (17) is connected to the product pipeline (1-3); the tower kettle outlet of the silane vaporization tower (28) is connected to the tube-side inlet of the silane vaporization tower reboiler (30), and the tube-side outlet of the silane vaporization tower reboiler (30) is connected to the middle and lower part of the silane vaporization tower (28); the shell-side inlet of the silane vaporization tower reboiler (30) is connected to the outlet of the difluorochloromethane booster pump (32), the shell-side outlet of the silane vaporization tower reboiler (30) is connected to the inlet of the difluorochloromethane buffer tank (31), and the outlet of the difluorochloromethane buffer tank (31) is connected to the inlet of the difluorochloromethane booster pump (32).

8. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 7, characterized in that: It also includes a silane impurity venting pipeline (1-4), a buffer tank tail gas cryogenic refrigerator (35) and a silane gas phase venting pipeline (1-6), the gas outlet of the silane separation tower condenser (27), the gas outlet of the silane vaporization tower condenser (29) and the gas outlet of the six-stage cryogenic refrigerator (22) are connected in parallel to the silane impurity venting pipeline (1-4); the air inlet of the buffer tank tail gas cryogenic refrigerator (35) is connected to the gas outlet of the silane buffer tank (34), and the gas outlet of the buffer tank tail gas cryogenic refrigerator (35) is connected to the silane gas phase venting pipeline (1-6).

9. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 2, characterized in that: It comprises a first pipeline for connecting the stuffing box area of the silane reaction tower (7) and the bottom material outlet of the light removal tower (2), and the first pipeline is provided with a trichlorosilane pressure pump (6).

10. The device for preparing electronic-grade silane gas in a single pass in a granular silicon production process according to claim 1, characterized in that: The invention also comprises a feed pipeline (1-1) for feeding mixed trichlorosilane raw material, wherein the feed pipeline (1-1) is connected to the inlet of the preheater (1).

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