An energy-saving electronic-grade polysilicon cold hydrogenation process device system and production method

Abstract

The present invention relates to an energy-saving electronic-grade polysilicon cold hydrogenation process device system and production method. In the device system, the reaction gas phase outlet of the reactor, a first-stage waste heat recovery heat exchange unit, a gas-solid separation and dust removal unit, a first-stage washing unit, a second-stage waste heat recovery heat exchange unit, a first-stage gas-liquid separation unit, a second-stage washing unit, a cooling unit, a second-stage gas-liquid separation unit, a pressure swing adsorption unit and a circulation unit are connected in sequence along the flow direction of the gas. The reaction gas phase flowing out of the reactor is used as a heat source for the first-stage waste heat recovery heat exchange unit and the second-stage waste heat recovery heat exchange unit to preheat the raw materials, and the chlorosilane in the tail gas is removed by the pressure swing adsorption unit, abandoning the extremely energy-consuming deep cooling mode of the traditional process, improving the energy utilization rate of the system, reducing the energy consumption of the system, and ensuring that the product quality can match the production requirements of electronic-grade polysilicon.

Description

Technical Field

[0001] The present invention relates to the technical field of polysilicon production, and in particular to an energy-saving electronic-grade polysilicon cold hydrogenation process device system and a production method. Background Art

[0002] In the production of polysilicon using the modified Siemens process, or by disproportionation to produce polysilicon, or silane, trichlorosilane is used as the raw material, and the target product is obtained through thermal decomposition or disproportionation. However, both the decomposition and disproportionation reactions produce a large amount of silicon tetrachloride as a byproduct. If this silicon tetrachloride cannot be properly recycled and utilized, the production cost of polysilicon or silane will increase dramatically.

[0003] In order to solve the problem of recycling a large amount of by-product silicon tetrachloride, the current production process of polysilicon or silane gas is usually to convert silicon tetrachloride into raw material trichlorosilane through a hydrogenation method and use it for the production of polysilicon or silane gas, that is, to rationally utilize silicon tetrachloride through a closed production loop to achieve the effect of reducing costs. At present, the methods for synthesizing trichlorosilane from silicon tetrachloride mainly include thermal hydrogenation and cold hydrogenation. Among them, the thermal hydrogenation method is an important method for treating silicon tetrachloride in the early stage. It mainly uses silicon tetrachloride and hydrogen as raw materials, and heats them with a graphite heating element at a temperature of 1200-1250℃ to perform a thermal reduction reaction to generate trichlorosilane. However, this method needs to be carried out at a temperature of 900-1400℃ or even higher and a high pressure of 1-35MPa, which consumes a lot of energy. In addition, the heating device used is an isostatically pressed graphite tape, which is easy to form gases such as methane under high temperature and high pressure conditions, which brings carbon pollution to the product in the closed-loop production of polysilicon or silane gas.

[0004] Currently, the cold hydrogenation process is a hot topic in this field due to its advantages such as low cost, high yield, and environmental friendliness. It also avoids graphite recrystallization and improves the production efficiency of polysilicon or silane gas. It mainly uses copper-based or iron-based catalysts to add silicon powder and hydrogen to a fluidized bed at a temperature of 400-800°C and a pressure of 2-4MPa, causing it to react with silicon tetrachloride to produce trichlorosilane. Currently, the highest conversion rate of cold hydrogenation technology has exceeded 35%, greatly reducing production costs. However, with the rapid development of the industry and the instability of the product's terminal market price, the conversion rate of silicon tetrachloride is no longer the only goal pursued by the cold hydrogenation process. The safety issues, long-term operation cycle issues, and energy consumption issues of the production process have received increasing attention. Energy consumption, in particular, is the next important direction for reducing production costs.

[0005] For example, CN103896280A discloses a method for cold hydrogenation of polysilicon, in which a cryogenic heat exchanger and a gas-liquid separator are used to freeze the polysilicon to -40 to -55°C for gas-liquid separation, thereby separating hydrogen and chlorosilane. However, this method has disadvantages such as high refrigeration costs and high energy consumption.

[0006] Therefore, providing an energy-saving electronic-grade polysilicon cold hydrogenation process device system and production method is a technical problem that needs to be solved in the current field. Summary of the Invention

[0007] In response to the above problems, the purpose of the present invention is to provide an energy-saving electronic-grade polysilicon cold hydrogenation process device system and production method. Compared with the existing technology, the device system and production method provided by the present invention can significantly improve the energy utilization rate of the system and reduce the system energy consumption, while ensuring that the product quality can match the production requirements of electronic-grade polysilicon and ensure the stable and safe operation of the system.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides an apparatus system for an energy-saving electronic-grade polysilicon cold hydrogenation process, the apparatus system comprising a reactor;

[0010] The reaction gas phase outlet of the reactor, a first stage waste heat recovery and heat exchange unit, a gas-solid separation and dust removal unit, a first stage washing unit, a second stage waste heat recovery and heat exchange unit, a first stage gas-liquid separation unit, a second stage washing unit, a cooling unit, a second stage gas-liquid separation unit, a pressure swing adsorption unit and a circulation unit are sequentially connected along the flow direction of the gas;

[0011] The reaction gas phase outlet of the reactor is connected to the heat source inlet of a waste heat recovery heat exchange unit, and the heat source outlet of the waste heat recovery heat exchange unit is connected to the gas-solid separation and dust removal unit;

[0012] The gas phase outlet of the first stage washing unit is connected to the heat source inlet of the second stage waste heat recovery and heat exchange unit, and the heat source outlet of the second stage waste heat recovery and heat exchange unit is connected to the first stage gas-liquid separation unit;

[0013] The purified gas phase outlet of the pressure swing adsorption unit is connected to the circulation unit, and the desorbed gas outlet of the pressure swing adsorption unit is connected to the distillation separation unit;

[0014] The circulation unit is also connected to a silicon tetrachloride air inlet and a hydrogen air inlet, and the mixed raw material outlet of the circulation unit is connected to the cold source inlet of the second stage waste heat recovery and heat exchange unit;

[0015] The cold source outlet of the second-stage waste heat recovery and heat exchange unit is connected to the cold source inlet of the first-stage waste heat recovery and heat exchange unit through the vaporization unit. The cold source outlet of the first-stage waste heat recovery and heat exchange unit is connected to the inlet of the reactor through the electric heating unit. The inlet of the reactor is also connected to the silicon powder feeding unit.

[0016] Based on the above technical scheme, the device system provided by the present invention can, on the one hand, deeply recycle and utilize the heat of the reaction output gas phase through the setting of a first-stage waste heat recovery heat exchange unit and a second-stage waste heat recovery heat exchange unit, thereby reducing the energy consumption of the system; on the other hand, a pressure swing adsorption unit based on the internal pressure difference operation of the system without additional power consumption is used to remove the residual chlorosilane in the exhaust gas, abandoning the extremely energy-consuming deep cooling mode of the traditional process, realizing the separation of chlorosilane, significantly improving the low temperature level of the cooling unit, and greatly saving the refrigeration cost; on the other hand, through the setting of the gas-solid separation and dust removal unit, the first-stage washing unit, and the second-stage washing unit, it can maximize the recovery of silicon and deeply remove impurities such as iron, aluminum, calcium, sulfur, and phosphorus, so that the product quality meets the production requirements of electronic-grade polysilicon.

[0017] In the present invention, the reactor is generally a fluidized bed reactor, and preferably a cyclone separator is configured in the reactor, which is arranged inside the reactor or outside the reactor as part of the gas-solid separation and dust removal unit. It is preferably arranged inside the reactor, which can reduce the complexity of the device system and simplify the operation. A silicon powder collection tank is generally provided at the bottom of the cyclone separator, and the silicon powder obtained in the silicon powder collection tank is generally discharged to a silicon powder recovery feed tank, and then enters the reactor to complete the recovery of solid silicon. The above-mentioned vaporization unit and electric heating unit are not particularly limited, and can be any unit used in the art for vaporizing raw materials or electrically heating raw materials. The device, the vaporization unit can be, for example, a vaporizer, and the electric heating unit can be, for example, an electric heater; the above-mentioned silicon powder feeding unit is not particularly limited, and any silicon powder feeding device commonly used in the art can be used, for example, two stepped tanks are set, namely a silicon powder storage tank and a silicon powder feeding tank, the raw silicon powder is pre-stored and treated in the silicon powder storage tank, and then fed into the silicon powder feeding tank, and then enters the reactor; the above-mentioned circulation unit is not particularly limited, for example, it can include a compressor and a mixer, first pressurizing the raw gas and the raw liquid separately, and then entering the mixer for mixing, and then feeding it into the second-stage waste heat recovery heat exchange unit. In the present invention, the raw gas or raw liquid is controlled by the circulation unit and then the heat exchange of the second-stage waste heat recovery heat exchange unit is carried out, which can reduce the partial pressure of silicon tetrachloride in the gas phase, increase the vaporization rate, and reduce energy consumption. The above-mentioned pressure swing adsorption unit can adsorb a small amount of chlorosilane in the gas phase. For example, it can be a pressure swing adsorption tower. The pressure swing adsorption unit generally includes an even number of units such as 2, 4, and 6. Half of the units are used for adsorption and the other half of the units are used for desorption, thereby realizing the concentration of hydrogen in the gas phase, and thus entering the circulation unit as a reaction raw material. Based on the principle of pressure swing adsorption and the current situation that the pressure difference between the front-end system and the distillation separation unit is higher than 2MPa, the gas desorbed from the pressure swing adsorption unit can be directly sent to the distillation separation unit, abandoning the extremely energy-consuming deep cooling mode of the traditional process to remove residual chlorosilane in the tail gas. The present invention automatically switches the adsorption and desorption operations through an automatic regulating valve.

[0018] As a preferred technical solution of the present invention, the gas phase outlet of the gas-solid separation and dust removal unit is connected to a first-stage washing unit;

[0019] The solid phase outlet of the gas-solid separation and dust removal unit is connected to the reactor;

[0020] The liquid phase outlet of the first stage washing unit is connected to the first stage sedimentation circulation unit;

[0021] The supernatant outlet of the first-stage sedimentation circulation unit is connected to a first-stage washing unit;

[0022] The liquid phase outlet of the first-level gas-liquid separation unit is connected to the first-level product collection unit;

[0023] The liquid phase outlet of the first-stage product collecting unit is connected to a first-stage washing unit;

[0024] The gas phase outlet of the first-stage gas-liquid separation unit is connected to the second-stage washing unit;

[0025] The liquid phase outlet of the second-stage washing unit is connected to the secondary sedimentation circulation unit;

[0026] The supernatant outlet of the secondary sedimentation circulation unit is connected to the second-stage washing unit;

[0027] The gas phase outlet of the second-stage washing unit is connected to the cooling unit;

[0028] The outlet of the cooling unit is connected to the secondary gas-liquid separation unit;

[0029] The liquid phase outlet of the secondary gas-liquid separation unit is connected to the secondary product collection unit;

[0030] The liquid phase outlet of the secondary product collection unit is connected to the second-stage washing unit;

[0031] The gas phase outlet of the secondary gas-liquid separation unit is connected to the pressure swing adsorption unit.

[0032] Based on the above technical solution, the fine silicon powder and other impurities in the gas phase are removed through a first-stage washing unit. The intercepted silicon powder and impurities enter the first-stage sedimentation circulation unit with the washing liquid. After sedimentation separation, the supernatant is circulated back to the first-stage washing unit as the source of the spray liquid. The deposited silicon and impurities are discharged and enter the subsequent slurry system for treatment. The reaction product after the second-stage waste heat recovery and heat exchange unit is in a gas-liquid mixed state. It is separated by a first-stage gas-liquid separation unit. The separated chlorosilane liquid is collected by a first-stage product collection unit and part of the product is returned to the first-stage washing as the source of the spray liquid. The gas phase obtained by the first-stage gas-liquid separation unit undergoes a second-stage washing. The washing liquid containing silicon powder and impurities discharged from the second-stage washing enters a second-stage sedimentation circulation unit. After sedimentation separation, the supernatant is used as the spray liquid of the second-stage washing unit. The deposited chlorosilane liquid containing fine silicon powder and impurities is discharged and enters the slurry system. The gas phase obtained from the second-stage scrubbing is condensed again in a cooling unit and then separated in a secondary gas-liquid separation unit. The separated liquid phase is then collected in a secondary product collection unit, with some of the product returning to the second-stage scrubbing as a source of spray liquid. The separated gas phase is then fed into a pressure swing adsorption unit to further remove residual chlorosilanes from the tail gas. The present invention utilizes multi-stage scrubbing, multi-stage sedimentation cycles, and multi-stage product collection to further ensure the thorough removal of silicon powder and impurities.

[0033] In the present invention, the above-mentioned first-stage washing unit can adopt any device used for gas phase washing in the art, for example, it can be a washing tower, preferably a plate tower structure, and the tower plate is preferably a sieve plate or a float valve; the above-mentioned second-stage washing unit can be, for example, a washing tower, preferably a packed tower structure, for example, a packed tower with structured packing or a packed tower with bulk packing; the above-mentioned first-stage sedimentation circulation unit or the first-stage sedimentation circulation unit can be, for example, a plurality of sedimentation circulation tanks arranged in parallel to ensure that the liquid in the tank has sufficient residence time and control the tank volume; the above-mentioned first-stage product collection unit or the second-stage product collection unit can be, for example, a product collection tank, preferably a collection tank with a conical bottom.

[0034] As a preferred technical solution of the present invention, the overflow outlet of the primary product collecting unit is connected to the secondary product collecting unit;

[0035] The overflow outlet of the secondary product collection unit is connected to the finished product collection unit;

[0036] The outlet of the finished product collecting unit is connected to the distillation separation unit.

[0037] Based on the above technical solution, after the primary product collection unit or the secondary product collection unit collects the liquid, part of the liquid at the bottom enters the slurry system to discharge the silicon and impurities that may be contained therein, and part of the liquid product overflows from the primary product collection unit to the secondary product collection unit, and then overflows from the secondary product collection unit to the finished product collection unit, which can further improve the purity of the product.

[0038] As a preferred technical solution of the present invention, the top product outlet of the distillation separation unit leads to a trichloro product discharge pipeline;

[0039] A tetrachloro product discharge pipeline is drawn out from the bottom product outlet of the distillation separation unit and is connected to a circulation unit.

[0040] Based on the above technical solution, the distillation separation unit can further collect the product from the top of the tower and recover the tetrachloroproduct at the bottom of the tower and recycle it into the system. The distillation separation unit can adopt any distillation tower commonly used in the art, such as a plate tower, a packed tower, or a dividing wall tower, preferably a dividing wall tower.

[0041] As a preferred technical solution of the present invention, the gas-solid separation and dust removal unit includes one or more of a cyclone separator, a venturi scrubber or a microporous filter element;

[0042] The cooling unit is provided with one or more of a waste heat recovery refrigeration unit, an air cooling heat removal device, a circulating water heat removal device or a chilled water heat removal device;

[0043] The chilled water outlet of the waste heat recovery refrigeration unit is connected to the chilled water heat removal device.

[0044] Based on the above technical solution, when a cyclone separator is provided in the reactor, the gas-solid separation and dust removal unit includes any one of a cyclone separator, a venturi scrubber or a microporous filter cartridge filter, preferably a venturi scrubber or a microporous filter cartridge filter, and more preferably a microporous filter cartridge filter. When a cyclone separator is not provided in the reactor, the gas-solid separation and dust removal unit can select one or two gas-solid separation devices. When one is selected, a microporous filter cartridge filter or a venturi scrubber is preferred. When two are selected, the first stage separation preferably adopts a cyclone separator or a microporous filter cartridge filter, more preferably a microporous filter cartridge filter, and the second stage separation preferably adopts any one of a cyclone separator, a microporous filter cartridge filter or a venturi scrubber. The venturi scrubber is provided at the rear section of a waste heat recovery heat exchange unit. The microporous filter cartridge filter can generally be provided at the front, middle or rear section of a waste heat recovery heat exchange unit. In the present invention, it is provided at the rear section of a waste heat recovery heat exchange unit. The cooling system can use a waste heat recovery refrigeration unit to produce any one of chilled water cooling, air cooling, circulating water cooling or chilled water cooling, or a combination of at least two methods for cascade refrigeration. Preferably, a combination of circulating water cooling and chilled water cooling or a waste heat recovery refrigeration unit to produce chilled water cooling, circulating water cooling and chilled water cooling is used. The waste heat recovery refrigeration unit can, for example, use an ammonia refrigeration unit, and its power comes from the reaction gas phase entering the cooling unit. The produced chilled water is directly used in the subsequent chilled water heat removal device for the final cooling of the exhaust gas by the cooling unit.

[0045] As a preferred technical solution of the present invention, the filtration pore size of the microporous filter element is 0.05-20μm, for example, it can be 0.05μm, 1μm, 2μm, 5μm, 8μm, 10μm, 12μm, 15μm, 18μm or 20μm, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 0.05-10μm.

[0046] Based on the above technical solution, the present invention can further effectively remove silicon powder and impurities to ensure the purity of the product.

[0047] As a preferred technical solution of the present invention, 1-4 stages of heat exchangers are arranged in a waste heat recovery heat exchange unit, preferably 2-4 stages, and more preferably 2-3 stages.

[0048] Based on the above technical solution, the present invention can effectively utilize the heat exchange between the reaction gas phase and the raw material phase to cool the reaction gas phase and preheat the raw material gas. In the present invention, the heat exchanger preferably uses a heat exchange tube with expansion compensation or a special-shaped heat exchange tube with an expanded heat exchange area, such as a special-shaped tube heat exchanger with an internal corrugated and externally threaded structure. This helps improve heat exchange efficiency, raises the raw material gas to a higher temperature, and cools the reaction gas phase to a lower temperature. This reduces the energy consumption of the electric heating unit on the feed side and the cooling unit on the exhaust side, thereby reducing the energy consumption of the system.

[0049] In a second aspect, the present invention provides a production method for an energy-saving electronic-grade polysilicon cold hydrogenation process, the production method being used in the apparatus system for the energy-saving electronic-grade polysilicon cold hydrogenation process described in the first aspect of the present invention, the production method comprising the following steps:

[0050] The silicon powder and the raw gas are subjected to a cold hydrogenation reaction in a reactor to obtain a reaction gas phase;

[0051] The reaction gas phase is sequentially subjected to secondary preheating of subsequent raw materials, gas-solid separation and dust removal, a first stage of washing, a first preheating of subsequent raw materials, a first stage of gas-liquid separation, a second stage of washing, cooling, a second stage of gas-liquid separation and pressure swing adsorption, the pressure swing adsorption obtains purified recovered hydrogen, the desorbed gas obtained by the pressure swing adsorption is subjected to rectification and separation, a trichloro product is obtained at the top of the tower, and a recovered tetrachloro product is obtained in the bottom of the tower;

[0052] The raw material gas is obtained by sequentially preheating, vaporizing, preheating and electrically heating the mixed raw material, and the mixed raw material includes hydrogen, tetrachlorosilane, recovered hydrogen and recovered tetrachloro products.

[0053] The production method provided by the present invention is based on the device system provided by the present invention. It realizes the recovery and utilization of waste heat and energy saving through primary preheating, secondary preheating, mixing first and then preheating, etc., replaces the deep cooling operation of the existing process by pressure swing adsorption, greatly saves refrigeration costs, and realizes the recovery of silicon powder and deep removal of impurities through gas-solid separation dust removal and multi-stage washing, thereby ensuring that the quality of the cold hydrogenation product can match the production of electronic-grade polysilicon.

[0054] As a preferred technical solution of the present invention, the temperature of the raw materials after the primary preheating is 105-135°C, for example, it can be 105°C, 106°C, 108°C, 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C or 135°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0055] The temperature of the reaction gas phase after the primary preheating is 80-120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 80-100°C;

[0056] The temperature of the vaporized raw material is 140-170° C., for example, 140° C., 142° C., 145° C., 148° C., 150° C., 152° C., 155° C., 158° C., 160° C., 162° C., 165° C., 168° C., or 170° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0057] The temperature of the raw materials after the secondary preheating is 450-520°C, for example, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C or 520°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0058] The temperature of the reaction gas phase after the secondary preheating is 160-280°C, for example, 160°C, 170°C, 180°C, 190°C, 200°C, 220°C, 240°C, 260°C or 280°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 180-260°C, more preferably 200-240°C;

[0059] The cooling end point temperature is 10-20°C, for example, 10°C, 12°C, 14°C, 16°C, 18°C ​​or 20°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] Based on the above technical solution, the present invention realizes heat exchange between the raw material and the reaction gas phase through primary preheating and secondary preheating. The raw material is not completely vaporized after the above-mentioned primary preheating. After the subsequent vaporization operation, the raw material is completely vaporized or overheated. Preferably, the raw material gas is partially overheated.

[0061] As a preferred technical solution of the present invention, the operating pressure of the cold hydrogenation reaction is 1.0-4.0 MPaG, for example, it can be 1 MPaG, 1.5 MPaG, 2 MPaG, 2.5 MPaG, 3 MPaG, 3.5 MPaG or 4 MPaG, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 2.0-3.5 MPaG, more preferably 2.5-3.0 MPaG;

[0062] The temperature of the cold hydrogenation reaction is 450-650°C, for example, it can be 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C or 650°C, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. It is preferably 500-600°C, and more preferably 550-580°C.

[0063] Based on the above technical solution, silicon and raw gas undergo a cold hydrogenation reaction to convert silicon tetrachloride in the raw gas into trichlorosilane, a raw material required for the production process, to obtain a reaction gas phase.

[0064] As a preferred technical solution of the present invention, the washing liquid obtained after the first stage of washing is subjected to a first-stage sedimentation cycle;

[0065] The average residence time of the primary sedimentation cycle is 1-5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 2-4 hours, more preferably 2.5-3.5 hours;

[0066] The washing liquid obtained after the second stage washing is subjected to a secondary sedimentation cycle;

[0067] The average residence time of the secondary sedimentation cycle is 3-8h, for example, it can be 3h, 4h, 5h, 6h, 7h or 8h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 4-7h, and more preferably 5-6h.

[0068] Based on the above technical solution, by ensuring that the liquid in the tank has sufficient residence time, silicon powder and other impurities can be further promoted to settle at the bottom of the tank and then discharged into the slurry system.

[0069] As a preferred technical solution of the present invention, the production method comprises the following steps:

[0070] The mixed raw materials are preheated to 105-135°C, then vaporized to 140-170°C, then preheated to 450-520°C for the second time, and then electrically heated to the required reaction temperature to obtain raw gas;

[0071] The silicon powder, the recovered solid silicon and the raw gas are subjected to a cold hydrogenation reaction at a temperature of 450-650°C and an operating pressure of 1.0-4.0 MPaG to obtain a reaction gas phase;

[0072] The reaction gas phase is preheated twice for subsequent raw materials to a temperature of the reaction gas phase of 160-280°C, and then gas-solid separation and dust removal are performed. The obtained solid phase silicon is returned to the reactor, and the obtained gas phase is subjected to a first-stage washing. The washing liquid obtained after the first-stage washing is subjected to a first-stage sedimentation cycle, and the average residence time is controlled to be 1-5 hours. The obtained supernatant is reused for the first-stage washing. The gas phase obtained after the first-stage washing is preheated once for subsequent raw materials to a temperature of 80-120°C, and then subjected to a first-stage gas-liquid separation. The liquid phase obtained by the first-stage gas-liquid separation is collected as a product and part of the product is reused in the first-stage washing. The gas phase obtained by the first-stage gas-liquid separation is subjected to a second-stage washing. The washing liquid obtained by the second-stage washing is subjected to a second-stage sedimentation cycle, and the average residence time is controlled to be 3-8 hours. The obtained supernatant is reused for the second-stage washing. The gas phase obtained by the second-stage washing is cooled to 10-20°C, and then subjected to a second-stage gas-liquid separation. The liquid phase obtained by the second-stage gas-liquid separation is collected as a product and part of the product is reused in the second-stage washing.

[0073] Based on the above technical solution, the present invention can further ensure the deep removal of silicon powder and impurities through multi-stage washing, multi-stage sedimentation circulation and multi-stage product collection.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) The present invention can realize deep recovery and utilization of the heat of the gas phase produced by the reaction through the first stage waste heat recovery heat exchange unit and the second stage waste heat recovery heat exchange unit, thereby reducing the energy consumption of the system. The circulation unit is set before the second stage waste heat recovery heat exchange unit, so that the raw materials are first mixed in the circulation unit and then preheated in the second stage waste heat recovery heat exchange unit. The gas phase partial pressure of the chlorosilane component can be reduced, thereby making it easier to complete the vaporization of the liquid phase component, improving the efficiency of the heat transfer process, and achieving the effect of further reducing the energy consumption of the system.

[0076] (2) The present invention achieves the purpose of removing residual chlorosilanes in the tail gas by providing a pressure swing adsorption unit. The adsorption and desorption operations are achieved based on the pressure difference of the system, without the introduction of additional energy consumption. At the same time, it can abandon the extremely energy-consuming deep cooling mode used in the existing process, significantly improving the low temperature level of the cooling unit, which is about 45-65°C higher than the existing deep cooling temperature of -35 to -45°C, thereby saving deep cooling costs and further reducing system energy consumption. Taking the reactor scale of 200,000 tons / year trichlorosilane production capacity as an example, when the feed is 120,000 kg / h of silicon tetrachloride, the present invention can save the refrigeration load of the deep cooling system, which is about 1.043MW.

[0077] (3) On the one hand, the present invention can more efficiently separate and intercept the silicon powder and other impurities brought out of the reactor through the setting of the gas-solid separation and dust removal unit, ensuring that they are not brought into the subsequent device system in large quantities, thereby ensuring the quality of the product and ensuring the safe, stable and long-term operation of the subsequent device. At the same time, the solid silicon separated by the gas-solid separation and dust removal unit is directly returned to the reactor, which can reduce the overall silicon consumption of the reactor and indirectly reduce the energy consumption of the system; on the other hand, by adopting a two-stage washing setting, it can further ensure that part of the silicon powder that cannot be recovered and impurities such as iron, aluminum, calcium, sulfur, and phosphorus are deeply removed; on the other hand, by adopting a multi-stage product collection unit and a multi-stage sedimentation circulation unit, and realizing the final collection by a step-by-step overflow method, the maximum impurity content in the finished product collection unit is made to be below 10ppm, which can fully ensure the quality of the cold hydrogenation product and further ensure that the product meets the production requirements of matching electronic-grade polysilicon.

[0078] (4) The present invention adopts any one or a combination of at least two of the waste heat recovery refrigeration unit, air cooling heat removal device, circulating water heat removal device or chilled water heat removal device in the cooling unit, and can use the heat of the reaction tail gas as a driving heat source, which is used to prepare chilled water in the waste heat recovery refrigeration unit, and then the chilled water is used in the subsequent chilled water heat removal device, thereby reducing the cooling load required for terminal cooling and reducing the energy consumption of the system.

[0079] (5) The present invention can significantly improve the energy recovery efficiency of the system and reduce the energy consumption of the system. The energy recovery efficiency reaches more than 85%. More specifically, taking a reactor with a trichlorosilane production capacity of 200,000 tons / year as an example, when the feed is 120,000 kg / h of silicon tetrachloride, the energy utilization rate of the system is more than 88%. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is a schematic structural diagram of the device system described in Example 1 of the present invention;

[0081] Figure 2 This is a schematic diagram of the structure of the device system described in Example 2 of the present invention;

[0082] Figure 3 This is a schematic structural diagram of the device system described in Comparative Example 1 of the present invention;

[0083] Figure 4 This is a schematic structural diagram of the device system described in Comparative Example 2 of the present invention.

[0084] Among them, 1-reactor; 2-silicon powder feeding unit; 3-first stage waste heat recovery and heat exchange unit; 4-gas-solid separation and dust removal unit; 5-first stage washing unit; 6-second stage waste heat recovery and heat exchange unit; 7-first stage gas-liquid separation unit; 8-first stage sedimentation circulation unit; 9-first stage product collection unit; 10-second stage washing unit; 11-second stage sedimentation circulation unit; 12-cooling unit; 13-secondary gas-liquid separation unit; 14-secondary product collection unit; 15-pressure swing adsorption unit; 16-finished product collection unit; 17-distillation separation unit; 18-hydrogen recovery pipeline; 19-circulation unit; 20-silicon tetrachloride feeding pipeline; 21-hydrogen feeding pipeline; 22-chlorosilane pipeline; 23-trichloro product discharge pipeline; 24-tetrachloro product discharge pipeline; 25-vaporization unit; 26-electric heating unit. DETAILED DESCRIPTION

[0085] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0086] In a specific embodiment of the present invention, the present invention provides an energy-saving electronic grade polysilicon cold hydrogenation process device system, the energy-saving electronic grade polysilicon cold hydrogenation process production method is carried out in the device system, such as Figure 1 As shown, the device system includes a reactor 1, and is connected in sequence along the flow direction of the gas to the reaction gas phase outlet of the reactor 1, a first stage waste heat recovery heat exchange unit 3, a gas-solid separation and dust removal unit 4, a first stage washing unit 5, a second stage waste heat recovery heat exchange unit 6, a first stage gas-liquid separation unit 7, a second stage washing unit 10, a cooling unit 12, a second stage gas-liquid separation unit 13, a pressure swing adsorption unit 15 and a circulation unit 19;

[0087] The reaction gas phase outlet of the reactor 1 is connected to the heat source inlet of the first stage waste heat recovery heat exchange unit 3, the heat source outlet of the first stage waste heat recovery heat exchange unit 3 is connected to the gas-solid separation and dust removal unit 4, the gas phase outlet of the first stage washing unit 5 is connected to the heat source inlet of the second stage waste heat recovery heat exchange unit 6, the heat source outlet of the second stage waste heat recovery heat exchange unit 6 is connected to the primary gas-liquid separation unit 7, the purified gas gas phase outlet of the pressure swing adsorption unit 15 is connected to the circulation unit 19 via the hydrogen recovery pipeline 18, the desorption gas outlet of the pressure swing adsorption unit 15 is connected to the distillation separation unit 17 via the chlorosilane pipeline 22, and the circulation unit 19 is also connected to the silicon tetrachloride feed pipeline 20 via the silicon tetrachloride inlet and the hydrogen inlet The inlet of the circulation unit 19 is connected to the hydrogen feed pipeline 21, the mixed raw material outlet of the circulation unit 19 is connected to the cold source inlet of the second stage waste heat recovery and heat exchange unit 6, the cold source outlet of the second stage waste heat recovery and heat exchange unit 6 is connected to the cold source inlet of the first stage waste heat recovery and heat exchange unit 3 through the vaporization unit 25, the cold source outlet of the first stage waste heat recovery and heat exchange unit 3 is connected to the inlet of the reactor 1 through the electric heating unit 26, the inlet of the reactor 1 is also connected to the silicon powder feeding unit 2, the gas phase outlet of the gas-solid separation and dust removal unit 4 is connected to the first stage washing unit 5, the solid phase outlet of the gas-solid separation and dust removal unit 4 is connected to the reactor 1, the liquid phase outlet of the first stage washing unit 5 is connected to the first stage sedimentation circulation unit 8, and the supernatant outlet of the first stage sedimentation circulation unit 8 is connected to the first stage sedimentation circulation unit 8. The outlet of the first gas-liquid separation unit 7 is connected to the first product collecting unit 9, the liquid phase outlet of the first product collecting unit 9 is connected to the first washing unit 5, the gas phase outlet of the first gas-liquid separation unit 7 is connected to the second washing unit 10, the liquid phase outlet of the second washing unit 10 is connected to the secondary sedimentation circulation unit 11, the supernatant outlet of the secondary sedimentation circulation unit 11 is connected to the second washing unit 10, the gas phase outlet of the second washing unit 10 is connected to the cooling unit 12, the outlet of the cooling unit 12 is connected to the second gas-liquid separation unit 13, the liquid phase outlet of the second gas-liquid separation unit 13 is connected to the secondary product collecting unit 14, the secondary product collecting The liquid phase outlet of the unit 14 is connected to the second-stage washing unit 10, the gas phase outlet of the secondary gas-liquid separation unit 13 is connected to the pressure swing adsorption unit 15, the overflow outlet of the primary product collection unit 9 is connected to the secondary product collection unit 14, the overflow outlet of the secondary product collection unit 14 is connected to the finished product collection unit 16, the outlet of the finished product collection unit 16 is connected to the distillation separation unit 17, the top product outlet of the distillation separation unit 17 leads to the trichloro product discharge pipeline 23, the bottom product outlet of the distillation separation unit 17 leads to the tetrachloro product discharge pipeline 24 and is connected to the circulation unit 19, the gas-solid separation and dust removal unit 4 includes one or more of a cyclone separator, a Venturi scrubber or a microporous filter element filter,The cooling unit 12 is provided with one or more of a waste heat recovery refrigeration unit, an air cooling heat removal device, a circulating water heat removal device or a chilled water heat removal device, and the chilled water outlet of the waste heat recovery refrigeration unit is connected to the chilled water heat removal device.

[0088] The device system and production method provided by the present invention can significantly improve the energy utilization rate of the system and reduce the energy consumption of the system, while ensuring that the product quality can match the production requirements of electronic-grade polysilicon and ensure the stable and safe operation of the system. The technical effects of the present application are further illustrated below from Examples 1-2 and Comparative Examples 1-2.

[0089] Example 1

[0090] This embodiment provides an energy-saving electronic-grade polysilicon cold hydrogenation process device system and production method, the production method is carried out in the energy-saving electronic-grade polysilicon cold hydrogenation process device system, the device system is as follows Figure 1 As shown, taking a reactor scale with a trichlorosilane production capacity of 200,000 tons / year and a silicon tetrachloride feed rate of 120 t / h as an example, the production method comprises the following steps:

[0091] The silicon powder and the raw gas are subjected to a cold hydrogenation reaction in the reactor 1 to convert the silicon tetrachloride in the raw gas into trichlorosilane, a raw material required for the production process. The reaction temperature is controlled at 560°C and the operating pressure is 3.0 MPaG to obtain a reaction gas phase. A cyclone separator is provided in the reactor 1 to perform preliminary gas-solid separation of the reaction gas phase.

[0092] The silicon powder includes silicon powder from the silicon powder feeding unit 2 and recovered solid silicon; the preparation of the raw material gas includes: the mixed raw material is preheated to 120°C in the second-stage waste heat recovery heat exchange unit 6 to be in a gas-liquid two-phase state, and then enters the vaporization unit 25 to achieve complete vaporization at a temperature of 147°C, and continues to be superheated to 170°C, and then in the first-stage waste heat recovery heat exchange unit 3, a three-stage stepped heat exchange mode is used for secondary preheating to 500°C, the temperature between the step heat exchange can be freely changed, and in principle, the temperature difference between the steps of the step heat exchanger is evenly distributed, and then enters the electric heating unit 26 for electric heating to the reaction temperature required to obtain the raw material gas; the preparation of the mixed raw material includes: fresh raw hydrogen from the hydrogen feed pipeline 21 and recovered hydrogen from the hydrogen recovery pipeline 18 (total flow rate is about 35000Nm 3 ), and the raw material tetrachlorosilane from the silicon tetrachloride feed pipeline 20 and the recovered tetrachloro product from the tetrachloro product discharge pipeline 24 (total flow rate is about 120 t / h) are mixed in the circulation unit 19 to obtain a mixed raw material;

[0093] The reaction gas phase is sent to a waste heat recovery heat exchange unit 3 to preheat the subsequent raw materials for a second time until the temperature of the reaction gas phase drops to 210°C, and then enters the gas-solid separation and dust removal unit 4 for gas-solid separation and dust removal. In this embodiment, since the reactor 1 is already provided with a built-in cyclone separator, the gas-solid separation and dust removal unit 4 can only use a microporous filter element filter with a filtration accuracy of 10μm, which can intercept more than 99% of the silicon powder in the gas phase obtained by the reaction to obtain the recovered solid phase silicon and send it to the reactor 1 for recycling, thereby reducing the silicon consumption of the system;

[0094] The gas phase coming out of the gas-solid separation and dust removal unit 4 enters a washing unit 5, i.e., a washing tower, for a washing step, and further removes fine silicon powder and other impurities such as boron compounds, phosphorus compounds, aluminum compounds, iron compounds, etc., to ensure that these impurities do not enter the back section of the system in large quantities. In this embodiment, a sieve plate tower is used as the washing tower. After the first washing step, the washing liquid containing silicon powder and impurities is obtained at the bottom of the tower and discharged into the first-stage sedimentation circulation unit 8, i.e., the first-stage sedimentation circulation tank, for a first-stage sedimentation cycle, ensuring that the residence time of the material in the tank is 3 hours. Two identical tanks are set for independent operation in parallel. The first-stage sedimentation circulation tank has a conical structure so that the chlorosilane liquid with high silicon and impurity content is formed by sedimentation in the tank and continues to be discharged to other processes. The supernatant in the first-stage sedimentation circulation tank is reused for the first-stage washing and used as one of the sources of spray liquid at the top of the washing tower.

[0095] The temperature of the gas phase obtained after the first stage of washing is about 145°C, and it enters the second stage waste heat recovery heat exchange unit 6 to preheat and partially vaporize the subsequent raw materials until the temperature drops to 105°C. The gas phase coming out of the second stage waste heat recovery heat exchange unit 6 begins to condense, and the gas-liquid two-phase logistics enters the first stage gas-liquid separation unit 7 for gas-liquid separation, and the obtained liquid phase enters the first stage product collection unit 9, i.e., the first stage product collection tank, for product collection. The first stage product collection tank has a conical structure, which is conducive to the discharge of the product at the bottom of the tank to other processes. A part of the product in the tank is reused in the first stage washing as another source of spray liquid at the top of the first stage washing tower. The first stage product collection tank has an overflow structure, and the chlorosilane liquid after sedimentation can enter the second stage product collection unit 14, i.e., the second stage product collection tank, in an overflow manner;

[0096] The gas phase obtained by the primary gas-liquid separation enters the second-stage washing unit 10, i.e., the second-stage washing tower, for second-stage washing. The second-stage washing tower adopts a packed tower, and the packing adopts a regular corrugated packing. The washing liquid containing silicon powder and impurities at the bottom of the second-stage washing tower is discharged into the secondary sedimentation circulation unit 11, i.e., the secondary sedimentation circulation tank, for secondary sedimentation circulation, ensuring that the residence time of the material is 5 hours. Two identical tanks are set for parallel independent operation. The secondary sedimentation circulation tank has a conical structure so that the chlorosilane liquid with high silicon and impurity content formed after sedimentation in the tank is continuously discharged to other processes. The supernatant in the secondary sedimentation circulation tank is reused for the second-stage washing as one of the sources of tower top spray liquid;

[0097] The gas phase temperature obtained by the second stage washing is about 95°C and enters the cooling unit 12. In this embodiment, the cooling unit 12 uses three cooling methods, namely, waste heat recovery refrigeration unit to produce chilled water, circulating water cooling and chilled water cooling, to cool the gas phase. The reaction gas phase is first used as a driving heat source to drive the refrigeration unit (using an ammonia refrigeration unit) to produce chilled water, thereby reducing the temperature of the gas phase to 85°C. The gas phase then enters the circulating water cooling heat removal device for circulating water cooling, and then enters the chilled water heat removal device for terminal cooling. Part of the chilled water in the chilled water heat removal device comes from the chilled water produced by the refrigeration unit, and the insufficient water is provided by the outside of the system. The gas phase is cooled to a temperature of 10°C in the cooling unit 12.

[0098] When step cooling is performed in the cooling unit 12, gas phase condensation also occurs. The resulting gas-liquid two-phase flow enters the secondary gas-liquid separation unit 13 for gas-liquid separation, and the resulting liquid phase enters the secondary product collection unit 14, i.e., the secondary product collection tank, for product collection. The secondary product collection tank has a conical structure, which is conducive to the discharge of products to other processes. A portion of the product in the tank is reused in the second-stage washing as another source of liquid phase spraying at the top of the tower. The secondary product collection tank has an overflow structure, and the settled chlorosilane product can overflow into the finished product collection unit 16, i.e., the finished product collection tank.

[0099] The gas phase obtained from the secondary gas-liquid separation enters the pressure swing adsorption unit 15 for pressure swing adsorption to adsorb chlorosilane in the gas phase to increase the concentration of hydrogen. After pressure swing adsorption, the concentration of the recovered hydrogen is increased to more than 99% and is sent to the circulation unit 19 through the hydrogen recovery pipeline 18;

[0100] The pressure swing adsorption unit 15 performs desorption, and the obtained desorbed gas, i.e., chlorosilane gas, is sent to the distillation separation unit 17 through the chlorosilane pipeline 22 and the product in the finished product collection tank for distillation separation. The pressure difference between the front-end device system of the distillation separation unit 17 and the distillation separation unit 17 is also the fundamental reason why the pressure swing adsorption unit 15 can operate without power between adsorption and desorption. After distillation separation, the product mainly composed of trichlorosilane is obtained at the top of the tower and enters the subsequent process section through the trichloro product discharge pipeline 23. The product mainly composed of silicon tetrachloride with a purity of ≥98% is obtained in the bottom of the tower and enters the circulation unit 19 through the tetrachloro product discharge pipeline 24.

[0101] In this embodiment, the heat exchangers used in the first-stage waste heat recovery and heat exchange unit and the second-stage waste heat recovery and heat exchange unit both adopt special-shaped tube heat exchangers with an internal corrugated and external threaded structure.

[0102] In this embodiment, a pressure swing adsorption unit 15 is provided to remove residual chlorosilanes in the tail gas, and adsorption and desorption operations are achieved based on the pressure difference of the system. There is no introduction of additional energy consumption, and at the same time, the extremely energy-consuming deep cooling mode used in the existing process can be abandoned, significantly improving the low temperature level of the cooling unit 12 by about 45-55°C (compared to the deep cooling to -35 to -45°C in the existing cooling unit), thereby saving deep cooling costs and further reducing system energy consumption. Taking the reactor scale of 200,000 tons / year trichlorosilane production capacity as an example, when the feed is 120,000 kg / h of silicon tetrachloride, the present invention can save the refrigeration load of the deep cooling system by about 1.043MW.

[0103] In this embodiment, deep removal of silicon powder and impurities such as iron, aluminum, calcium, sulfur, and phosphorus in the product can be achieved, so that the maximum impurity content in the finished product collection tank reaches below 10 ppm, which can fully ensure the quality of the cold hydrogenation product and further ensure that the product meets the production requirements of electronic-grade polysilicon.

[0104] In addition, in this embodiment, through multiple waste heat utilization methods and reducing system energy consumption, the system energy utilization rate can reach more than 88% under the conditions of a reactor scale with a trichlorosilane production capacity of 200,000 tons / year and a feed of 120,000 kg / h of silicon tetrachloride.

[0105] Example 2

[0106] This embodiment provides an energy-saving electronic grade polysilicon cold hydrogenation process device system, such as Figure 2 As shown, the difference between the device system and Example 1 is that the first-level sedimentation circulation unit, the second-level sedimentation circulation unit, the first-level product collection unit and the second-level product collection unit are not provided, and the liquid phase outlet of the first-level gas-liquid separation unit and the liquid phase outlet of the second-level gas-liquid separation unit are both connected to the finished product collection unit.

[0107] Compared with Example 2, the only difference between Example 1 is that Example 2 does not perform graded sedimentation circulation and graded product collection. Example 1 can make the maximum impurity content in the finished product collection tank reach below 10 ppm, while the impurity content level in Example 2 is about 150 ppm. It can be seen that the present invention can further improve the purity of the finished product by adopting graded sedimentation circulation and graded product collection, that is, the setting of a first-level sedimentation circulation unit, a second-level sedimentation circulation unit, a first-level product collection unit and a second-level product collection unit, which is beneficial to ensure that the product meets the production requirements of matching electronic-grade polysilicon.

[0108] Comparative Example 1

[0109] This comparative example provides an energy-saving electronic grade polysilicon cold hydrogenation process device system, such as Figure 3 As shown, the difference between the device system and Example 1 is that the secondary sedimentation circulation unit and the second-stage washing unit are not provided, and the gas phase outlet of the primary gas-liquid separation unit is connected to the cooling unit.

[0110] The only difference between Example 1 and Comparative Example 1 is that the second-stage washing and the secondary sedimentation cycle are not performed in Comparative Example 1. Example 1 can make the maximum impurity content in the finished product collection tank reach below 10 ppm, while the impurity content level in Comparative Example 1 is about 5000 ppm. It can be seen that the present invention can further improve the purity of the finished product by setting up the secondary sedimentation cycle unit and the second-stage washing unit, which is beneficial to ensure that the product meets the requirements for matching electronic-grade polysilicon production.

[0111] Comparative Example 2

[0112] This comparative example provides an energy-saving electronic grade polysilicon cold hydrogenation process device system, such as Figure 4 As shown, the difference between the device system and Example 1 is that the first-stage washing unit, the first-stage sedimentation circulation unit, the second-stage washing unit and the second-stage sedimentation circulation unit are not provided, the gas phase outlet of the gas-solid separation and dust removal unit is connected to the heat source inlet of the second-stage waste heat recovery and heat exchange unit, and the gas phase outlet of the first-stage gas-liquid separation unit is connected to the cooling unit.

[0113] Compared with Comparative Example 2, Example 1 differs only in that in Comparative Example 2, no one-stage washing, two-stage washing and graded sedimentation are performed, the gas phase after gas-solid separation and dust removal is directly subjected to two-stage waste heat recovery, and the gas phase after the first-stage gas-liquid separation is directly cooled. Example 1 can make the maximum impurity content in the finished product collection tank reach below 10 ppm, while the finished product collection tank in Comparative Example 2 contains about 3% impurities. It can be seen that the present invention can further improve the purity of the finished product by adopting one-stage washing and two-stage washing, as well as graded sedimentation operations, which is beneficial to ensure that the product meets the requirements for matching electronic-grade polysilicon production.

[0114] In summary, the device system and production method provided by the present invention can significantly improve the energy utilization rate of the system and reduce the energy consumption of the system, while ensuring that the product quality can match the production requirements of electronic-grade polysilicon and ensure the stable and safe operation of the system.

[0115] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. An energy-saving device for cold hydrogenation of electronic-grade polysilicon, characterized in that: The device includes a reactor; The reaction gas phase outlet of the reactor, a first stage waste heat recovery and heat exchange unit, a gas-solid separation and dust removal unit, a first stage washing unit, a second stage waste heat recovery and heat exchange unit, a first stage gas-liquid separation unit, a second stage washing unit, a cooling unit, a second stage gas-liquid separation unit, a pressure swing adsorption unit and a circulation unit are sequentially connected along the flow direction of the gas; The reaction gas phase outlet of the reactor is connected to the heat source inlet of a waste heat recovery heat exchange unit, and the heat source outlet of the waste heat recovery heat exchange unit is connected to the gas-solid separation and dust removal unit; The gas phase outlet of the first stage washing unit is connected to the heat source inlet of the second stage waste heat recovery and heat exchange unit, and the heat source outlet of the second stage waste heat recovery and heat exchange unit is connected to the first stage gas-liquid separation unit; The purified gas phase outlet of the pressure swing adsorption unit is connected to the circulation unit, and the desorbed gas outlet of the pressure swing adsorption unit is connected to the distillation separation unit; The circulation unit is also connected to a silicon tetrachloride air inlet and a hydrogen air inlet, and the mixed raw material outlet of the circulation unit is connected to the cold source inlet of the second stage waste heat recovery and heat exchange unit; The cold source outlet of the second-stage waste heat recovery and heat exchange unit is connected to the cold source inlet of the first-stage waste heat recovery and heat exchange unit via a vaporization unit, and the cold source outlet of the first-stage waste heat recovery and heat exchange unit is connected to the inlet of the reactor via an electric heating unit, and the inlet of the reactor is also connected to the silicon powder feeding unit; The gas phase outlet of the gas-solid separation and dust removal unit is connected to the first-stage washing unit; the solid phase outlet of the gas-solid separation and dust removal unit is connected to the reactor; the liquid phase outlet of the first-stage washing unit is connected to the first-stage sedimentation circulation unit; the supernatant outlet of the first-stage sedimentation circulation unit is connected to the first-stage washing unit; the liquid phase outlet of the first-stage gas-liquid separation unit is connected to the first-stage product collecting unit; the liquid phase outlet of the first-stage product collecting unit is connected to the first-stage washing unit; the gas phase outlet of the first-stage gas-liquid separation unit is connected to the second-stage washing unit; the liquid phase outlet of the second-stage washing unit is connected to the second-stage sedimentation circulation unit; the supernatant outlet of the second-stage sedimentation circulation unit is connected to the second-stage washing unit; the gas phase outlet of the second-stage washing unit is connected to the cooling unit; the outlet of the cooling unit is connected to the second-stage gas-liquid separation unit; the liquid phase outlet of the second-stage gas-liquid separation unit is connected to the second-stage product collecting unit; the liquid phase outlet of the second-stage product collecting unit is connected to the second-stage washing unit; the gas phase outlet of the second-stage gas-liquid separation unit is connected to the pressure swing adsorption unit; The overflow outlet of the primary product collecting unit is connected to the secondary product collecting unit; The overflow outlet of the secondary product collection unit is connected to the finished product collection unit; The outlet of the finished product collecting unit is connected to the distillation separation unit.

2. The device for energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 1, characterized in that: The top product outlet of the distillation separation unit leads to a trichloro product discharge pipeline; A tetrachloro product discharge pipeline is drawn out from the bottom product outlet of the distillation separation unit and is connected to a circulation unit.

3. The device for energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 1, characterized in that: The gas-solid separation and dust removal unit includes one or more of a cyclone separator, a venturi scrubber or a microporous filter element; The cooling unit is provided with one or more of a waste heat recovery refrigeration unit, an air cooling heat removal device, a circulating water heat removal device or a chilled water heat removal device; The chilled water outlet of the waste heat recovery refrigeration unit is connected to the chilled water heat removal device.

4. A production method of energy-saving electronic-grade polysilicon cold hydrogenation process, characterized in that: The production method uses the device of the energy-saving electronic-grade polysilicon cold hydrogenation process according to any one of claims 1 to 3, and the production method comprises the following steps: The silicon powder and the raw gas are subjected to a cold hydrogenation reaction in a reactor to obtain a reaction gas phase; The reaction gas phase is sequentially subjected to secondary preheating of subsequent raw materials, gas-solid separation and dust removal, a first stage of washing, a first preheating of subsequent raw materials, a first stage of gas-liquid separation, a second stage of washing, cooling, a second stage of gas-liquid separation and pressure swing adsorption, the pressure swing adsorption obtains purified recovered hydrogen, the desorbed gas obtained by the pressure swing adsorption is subjected to rectification and separation, the trichloro product is obtained at the top of the rectification tower, and the recovered tetrachloro product is obtained in the bottom of the tower; The raw material gas is obtained by sequentially preheating, vaporizing, preheating and electrically heating the mixed raw material, and the mixed raw material includes hydrogen, tetrachlorosilane, recovered hydrogen and recovered tetrachloro products.

5. The production method of energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 4, characterized in that: The temperature of the raw materials after the primary preheating is 105-135°C; The temperature of the reaction gas phase after the primary preheating is 80-120°C; The temperature of the vaporized raw material is 140-170°C; The temperature of the raw materials after the secondary preheating is 450-520°C; The temperature of the reaction gas phase after the secondary preheating is 160-280°C; The cooling end point temperature is 10-20°C.

6. The production method of energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 4, characterized in that: The operating pressure of the cold hydrogenation reaction is 1.0-4.0 MPaG; The temperature of the cold hydrogenation reaction is 450-650°C.

7. The production method of energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 4, characterized in that: The washing liquid obtained after the first stage of washing is subjected to a first-stage sedimentation cycle; The average residence time of the primary sedimentation cycle is 1-5 hours; The washing liquid obtained after the second stage washing is subjected to a secondary sedimentation cycle; The average residence time of the secondary sedimentation cycle is 3-8 hours.

8. The production method of energy-saving electronic-grade polysilicon cold hydrogenation process according to claim 4, characterized in that: The production method comprises the following steps: The mixed raw materials are preheated to 105-135°C, then vaporized to 140-170°C, then preheated to 450-520°C for the second time, and then electrically heated to the required reaction temperature to obtain raw gas; The silicon powder, the recovered solid silicon and the raw gas are subjected to a cold hydrogenation reaction at a temperature of 450-650°C and an operating pressure of 1.0-4.0 MPaG to obtain a reaction gas phase; The reaction gas phase is preheated twice for subsequent raw materials to a temperature of the reaction gas phase of 160-280°C, and then gas-solid separation and dust removal are performed. The obtained solid phase silicon is returned to the reactor, and the obtained gas phase is subjected to a first-stage washing. The washing liquid obtained after the first-stage washing is subjected to a first-stage sedimentation cycle, and the average residence time is controlled to be 1-5 hours. The obtained supernatant is reused for the first-stage washing. The gas phase obtained after the first-stage washing is preheated once for subsequent raw materials to a temperature of 80-120°C, and then subjected to a first-stage gas-liquid separation. The liquid phase obtained by the first-stage gas-liquid separation is collected as a product and part of the product is reused in the first-stage washing. The gas phase obtained by the first-stage gas-liquid separation is subjected to a second-stage washing. The washing liquid obtained by the second-stage washing is subjected to a second-stage sedimentation cycle, and the average residence time is controlled to be 3-8 hours. The obtained supernatant is reused for the second-stage washing. The gas phase obtained by the second-stage washing is cooled to 10-20°C, and then subjected to a second-stage gas-liquid separation. The liquid phase obtained by the second-stage gas-liquid separation is collected as a product and part of the product is reused in the second-stage washing.

Images