Polysilicon reduction tail gas hydrogen chloride desorption equipment and polysilicon production system

Abstract

The present invention provides a device for desorbing hydrogen chloride from the tail gas of polysilicon reduction, comprising a microwave reboiler, an ultrasonic gas-liquid separator, a condenser, a heat exchanger, and a pump. The outer wall of the ultrasonic gas-liquid separator is provided with a hollow jacket. The outlet of the microwave reboiler is connected to the inlet of the ultrasonic gas-liquid separator, the gas outlet of the ultrasonic gas-liquid separator is connected to the condenser, and the liquid outlet of the ultrasonic gas-liquid separator is connected to the heat exchanger. The outlet of the pump is connected to the inlet of the microwave reboiler via a pipeline, which is connected in series with the condenser, the heat exchanger, and the jacket. The pump drives the flow of a primary cold rich solution of chlorosilane containing hydrogen chloride. The device for desorbing hydrogen chloride from the tail gas of polysilicon reduction of the present invention has a reasonable layout, a simple structure, a simple process, high desorption efficiency, high heat utilization rate, and a prolonged equipment service life. The present invention also provides a polysilicon production system.

Description

Technical Field

[0001] The present invention belongs to the technical field of polysilicon production, and in particular relates to a polysilicon reduction tail gas hydrogen chloride desorption device and a polysilicon production system. Background Art

[0002] Currently, the domestic polysilicon production process primarily utilizes the modified Siemens process. In this process, the reduction reaction of trichlorosilane within the bell-jar reactor is often incomplete, resulting in the discharge of a large amount of unreacted products to downstream processes. To effectively utilize all materials and achieve closed-loop production, the post-reaction materials are recycled through downstream separation and purification processes.

[0003] Hydrogen chloride is separated by absorption and desorption. The absorbent for hydrogen chloride is typically a cold chlorosilane liquid, which then desorbs the hydrogen chloride from the chlorosilane. Traditionally, the desorption process utilizes heating within a desorption tower combined with a reboiler. However, this process is plagued by issues such as large desorption tower equipment and inefficient heat utilization. Furthermore, there are challenges such as low hydrogen chloride desorption efficiency, a complex desorption process, and high-temperature corrosion of the equipment.

[0004] While existing desorption equipment on the market has achieved some improvement through improvements to the internal structure of the desorption tower, the tower itself still suffers from inherent issues, including bulky equipment and suboptimal thermal energy utilization. Consequently, existing technologies still fail to effectively address the challenges of desorption of hydrogen chloride, the off-gas from polysilicon reduction. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a polysilicon reduction tail gas hydrogen chloride desorption device with a reasonable layout, simple structure and high heat utilization rate, and also provide a polysilicon production system.

[0006] The present invention provides a device for desorbing hydrogen chloride from polysilicon reduction tail gas, comprising a microwave reboiler, an ultrasonic gas-liquid separator, a condenser, a heat exchanger, and a pump. The outer wall of the ultrasonic gas-liquid separator is provided with a jacket, which is a hollow structure. The microwave reboiler is used to perform microwave heating on a cold chlorosilane-rich liquid containing hydrogen chloride to be desorbed to form a gas-liquid mixture of hydrogen chloride and chlorosilane. The outlet of the microwave reboiler is connected to the inlet of the ultrasonic gas-liquid separator. The ultrasonic gas-liquid separator is used to ultrasonically separate the gas-liquid mixture. The gas outlet of the ultrasonic gas-liquid separator is connected to the condenser, and the liquid outlet of the ultrasonic gas-liquid separator is connected to the heat exchanger. The hot hydrogen chloride gas and hot chlorosilane-lean liquid obtained after ultrasonic separation are respectively introduced into the condenser and the heat exchanger.

[0007] The outlet of the pump is connected to a condenser, a heat exchanger, and a jacket in series through a pipeline, and then connected to the inlet of a microwave reboiler. Chlorosilane containing hydrogen chloride in the polysilicon reduction tail gas, namely, a primary cold rich liquid, is driven by the pump to flow, and is condensed in the condenser by condensing the hot hydrogen chloride gas in the condenser to obtain a first-stage cold rich liquid; the first-stage cold rich liquid enters the heat exchanger and exchanges heat with the hot chlorosilane lean liquid in the heat exchanger to obtain a second-stage cold rich liquid; the second-stage cold rich liquid enters the jacket and exchanges heat with the gas-liquid mixture in the ultrasonic gas-liquid separator to obtain a third-stage cold rich liquid; the third-stage cold rich liquid is introduced into the microwave reboiler as the chlorosilane cold rich liquid containing hydrogen chloride to be desorbed.

[0008] Preferably, the microwave reboiler includes a shell and a microwave feeding probe, the inlet of the microwave reboiler is arranged at the upper part of the shell, the outlet of the microwave reboiler is arranged at the bottom of the shell, and the microwave feeding probe is arranged on the outer surface of the shell for feeding microwaves into the interior of the shell.

[0009] Preferably, the microwave reboiler further comprises a flow guide, which is arranged inside the shell and below the inlet of the microwave reboiler. The flow guide is connected to an external driving device and rotates under the drive of the external driving device. The flow guide is provided with a plurality of spirally arranged flow grooves for guiding the cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed entering the microwave reboiler.

[0010] Preferably, the lower portion of the shell is a conical structure with a gradually narrowing inner wall, and the bottom end of the guide groove of the deflector is connected to the top end of the conical structure of the shell.

[0011] Preferably, the ultrasonic gas-liquid separator includes a shell and an ultrasonic vibrator, the inlet, air outlet and liquid outlet of the ultrasonic gas-liquid separator are arranged on the shell from top to bottom in sequence, and the ultrasonic vibrator is installed on the outer surface of the shell and is located between the inlet and air outlet of the ultrasonic gas-liquid separator, and is used to feed ultrasonic vibration into the shell.

[0012] Preferably, the ultrasonic gas-liquid separator also includes a first filler, which is filled inside the shell corresponding to the position of the ultrasonic vibrator and is located between the inlet and the gas outlet of the ultrasonic gas-liquid separator, and is used to increase the dispersion of the gas-liquid mixture of hydrogen chloride and chlorosilane when it flows through the first filler.

[0013] Preferably, the ultrasonic gas-liquid separator also includes a liquid distributor, which is arranged inside the shell, with its top connected to the inlet of the ultrasonic gas-liquid separator, and its bottom split into multiple branch pipes, each branch pipe is provided with multiple liquid outlet holes for connecting the interior of the liquid distributor and the interior of the shell, and spraying the gas-liquid mixture of hydrogen chloride and chlorosilane obtained from the inlet of the ultrasonic gas-liquid separator into the interior of the shell.

[0014] Preferably, there is a gap between the liquid distributor and the shell, and the ultrasonic gas-liquid separator also includes a second filler, which is filled between the shell and the liquid distributor and is located below the gas outlet and above each liquid outlet, and is used to filter out chlorosilane in the hot hydrogen chloride gas after gas-liquid separation.

[0015] Preferably, the liquid outlet faces the inner wall of the shell.

[0016] Preferably, the inner wall of the shell is provided with folds having a sawtooth-shaped cross section.

[0017] The present invention also provides a polysilicon production system, comprising a bell-jar reactor and an absorption tower, and also comprising the above-mentioned polysilicon reduction tail gas hydrogen chloride desorption equipment, wherein the bell-jar reactor, the absorption tower and the polysilicon reduction tail gas hydrogen chloride desorption equipment are connected in sequence, the absorption tower absorbs and separates the hydrogen chloride gas discharged from the bell-jar reactor by using chlorosilane liquid to obtain a chlorosilane cold rich liquid containing hydrogen chloride to be desorbed from the polysilicon reduction tail gas, and the polysilicon reduction tail gas hydrogen chloride desorption equipment desorbs the chlorosilane cold rich liquid containing hydrogen chloride to be desorbed discharged from the absorption tower.

[0018] The polysilicon reduction tail gas hydrogen chloride desorption equipment disclosed in the present invention adopts a microwave reboiler and an ultrasonic gas-liquid separator to replace the traditional desorption tower equipment, so the overall equipment is more compact and the structure is simpler. Precisely because of the simpler structure, it is more convenient and quick to disassemble and maintain.

[0019] Microwave heating can rapidly heat the cold, rich liquid to be desorbed to a specified temperature, preventing high-temperature corrosion of the equipment caused by excessive temperatures. Ultrasonic gas-liquid separators use ultrasound to intensify the movement of microbubbles dissolved in the liquid. The thermal effect of ultrasound also reduces the solubility of the gas in the liquid, improving gas-liquid separation efficiency.

[0020] The pump connects each device in sequence, first exchanging heat between the primary cold rich liquid and the hot hydrogen chloride gas in the condenser to obtain a heated primary cold rich liquid. In this process, after the hot hydrogen chloride gas is cooled, the small amount of chlorosilane droplets contained in it are also separated due to the cooling, which not only improves the degree of desorption and the purity of the hydrogen chloride gas, but also effectively utilizes heat.

[0021] Afterwards, the first-stage cold rich liquid exchanges heat with the hot lean liquid in the heat exchanger to obtain the second-stage cold rich liquid, making full use of the excess heat in the hot lean liquid that would have been useless and wasted to heat the cold rich liquid.

[0022] Then the secondary cold rich liquid is passed into the jacket and exchanges heat with the gas-liquid mixture in the ultrasonic gas-liquid separator to obtain the tertiary cold rich liquid. This makes full use of the heat originally dissipated into the air through the outer wall of the ultrasonic gas-liquid separator to heat the cold rich liquid and simultaneously cool the gas-liquid mixture, thereby accelerating the gas-liquid separation between chlorosilane and hydrogen chloride.

[0023] Finally, the third-stage cold rich liquid is passed into the microwave reboiler as the cold rich liquid to be desorbed for microwave heating. Since the cold rich liquid has undergone three-stage heat exchange and temperature increase, its temperature is increased to a certain extent, which reduces the burden of microwave heating and reduces the microwave heating output.

[0024] In the series structure of the pumps, since the primary cold rich liquid is in the lowest temperature state, the heat exchange effect with the hot hydrogen chloride gas is the best. Then the useless waste heat in the hot lean liquid is utilized, and finally the waste heat dissipated by the gas-liquid mixture is utilized. It can be seen that the structural layout of this equipment is very reasonable. Through the multi-stage reasonably arranged heat exchange, the heat is fully utilized and the desorption efficiency is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the hydrogen chloride desorption device for polysilicon reduction tail gas in Example 1 of the present invention;

[0026] Figure 2 1 is a schematic structural diagram of a microwave reboiler in the polysilicon reduction tail gas hydrogen chloride desorption device in Example 1 of the present invention;

[0027] Figure 3 It is a structural schematic diagram of the ultrasonic gas-liquid separator in the polysilicon reduction tail gas hydrogen chloride desorption equipment in Example 1 of the present invention.

[0028] In the figure: 1. Microwave reboiler; 11. Shell; 111. First overflow port; 12. Microwave feed probe; 13. Flow guide; 2. Ultrasonic gas-liquid separator; 21. Jacket; 22. Gas outlet; 23. Liquid outlet; 24. Shell; 241. Second overflow port; 25. Ultrasonic vibrator; 26. Liquid distributor; 261. Branch pipe; 262. Liquid outlet; 27. First filler; 28. Second filler; 3. Condenser; 31. Gas outlet pipeline; 32. Small amount of cold lean liquid outlet pipeline; 4. Heat exchanger; 41. Main cold lean liquid outlet pipeline; 5. Pump. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "upper" and "lower" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience and simplification of the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0031] In the description of the present invention, the terms “first”, “second” and “third” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connect," "dispose," "install," "fix," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integral connection; they may refer to direct connection, indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0033] Example 1

[0034] like Figures 1 to 3 As shown, the polysilicon reduction tail gas hydrogen chloride desorption equipment of this embodiment includes a microwave reboiler 1, an ultrasonic gas-liquid separator 2, a condenser 3, a heat exchanger 4 and a pump 5. A jacket 21 is provided on the outer wall of the ultrasonic gas-liquid separator 2. The jacket 21 is a hollow structure for accommodating liquid.

[0035] Microwave reboiler 1 is used to microwave-heat the desorbed cold chlorosilane-rich liquid containing hydrogen chloride to form a gas-liquid mixture of hydrogen chloride and chlorosilane. The outlet of microwave reboiler 1 is connected to the inlet of ultrasonic gas-liquid separator 2, which is used to ultrasonically separate the gas-liquid mixture. The gas outlet 22 of ultrasonic gas-liquid separator 2 is connected to condenser 3, and the liquid outlet 23 of ultrasonic gas-liquid separator 2 is connected to heat exchanger 4. The hot hydrogen chloride gas and hot chlorosilane-lean liquid obtained after ultrasonic separation are respectively passed into condenser 3 and heat exchanger 4. In this embodiment, condenser 3 and heat exchanger 4 can be any of tubular heat exchangers, plate heat exchangers, and extended surface heat exchangers.

[0036] This equipment uses a microwave reboiler 1 and an ultrasonic gas-liquid separator 2 to replace the traditional desorption tower equipment, so the overall equipment is more compact and the structure is simpler. And precisely because the structure is simpler, it is more convenient and quicker to disassemble and maintain. Microwave heating can quickly heat the cold rich liquid to be desorbed to a specified temperature, avoiding high-temperature corrosion of the equipment caused by excessive temperature. The ultrasonic gas-liquid separator 2 uses ultrasound to intensify the movement of microbubbles dissolved in the liquid. At the same time, the thermal effect brought by ultrasound can also reduce the solubility of the gas in the liquid and improve the gas-liquid separation efficiency. The streamlines of the liquid, gas and gas-liquid mixture during the desorption process are as follows: Figure 1 Indicated by the lines with arrows.

[0037] In this embodiment, the gas-liquid mixture in the ultrasonic gas-liquid separator 2 is gradually separated into gas and liquid. By identifying the mass fraction of hydrogen chloride, when the mass fraction of hydrogen chloride in the chlorosilane hot lean liquid obtained after separation in the ultrasonic gas-liquid separator 2 is ≤2×10 -40 . When , it means that the gas-liquid separation meets the requirements and can enter the next process.

[0038] The outlet of pump 5 is connected to the inlet of microwave reboiler 1 via a pipeline, which connects to condenser 3, heat exchanger 4, and jacket 21 in series. Chlorosilanes containing hydrogen chloride in the polysilicon reduction tail gas, or primary cold rich liquid, are driven by pump 5 and condensed in condenser 3 to produce a primary cold rich liquid at a temperature of -25°C to -5°C. During this process, the hot hydrogen chloride gas cools, and the small amount of chlorosilane droplets contained within it are also separated due to the cooling. This not only improves the degree of desorption and the purity of the hydrogen chloride gas, but also effectively utilizes heat. The separated hydrogen chloride gas is transported to the next stage via gas outlet pipeline 31, and the cold chlorosilane liquid is transported to the next stage via a small amount of cold lean liquid outlet pipeline 32.

[0039] The first-stage cold rich liquid then enters heat exchanger 4, where it exchanges heat with the hot chlorosilane lean liquid at 77°C to 107°C, producing a second-stage cold rich liquid at 37°C to 57°C. This utilizes the otherwise wasted heat in the hot lean liquid to heat the cold rich liquid. The cooled lean liquid is then transported to the next stage via main cold lean liquid outlet pipeline 41.

[0040] Then, the secondary cold rich liquid enters the jacket 21 and exchanges heat with the gas-liquid mixture at 90°C to 120°C in the ultrasonic gas-liquid separator 2 to obtain the tertiary cold rich liquid at 56°C to 76°C. This fully utilizes the heat originally dissipated into the air through the outer wall of the ultrasonic gas-liquid separator to heat the cold rich liquid and simultaneously cool the gas-liquid mixture, thereby accelerating the gas-liquid separation between chlorosilane and hydrogen chloride.

[0041] Finally, the tertiary cold rich liquid is fed into the microwave reboiler 1 as the cold rich liquid containing hydrogen chloride to be desorbed, forming a closed loop. Since the cold rich liquid has undergone three stages of heat exchange and temperature increase, its temperature is increased to a certain extent, reducing the burden of microwave heating and the microwave heating output.

[0042] In the series structure of pump 5, since the primary cold rich liquid is in the lowest temperature state, when exchanging heat with the hot hydrogen chloride gas, the separation effect of the hot hydrogen chloride gas and the chlorosilane droplets is the best. Then, the useless waste heat in the hot lean liquid is utilized, and finally the waste heat emitted by the gas-liquid mixture is utilized. It can be seen that the structural layout of this equipment is very reasonable. Through the multi-stage reasonably arranged heat exchange, the heat is fully utilized, the desorption efficiency is effectively improved, and the comprehensive thermal energy utilization efficiency of the desorption equipment is improved. In this embodiment, the pump uses a fluoroplastic centrifugal pump, and its speed can be set to 2000rpm~3000rpm. By controlling the speed of the centrifugal pump, the liquid processing capacity is adjusted to 20m 3 / h~50m 3 / h.

[0043] In this embodiment, the microwave reboiler 1 includes a shell 11 and a microwave feeding probe 12. The inlet of the microwave reboiler 1 is arranged at the upper part of the shell 11, and the outlet of the microwave reboiler 1 is arranged at the bottom of the shell 11. The microwave feeding probe 12 is arranged on the outer surface of the shell 11 and is used to feed microwaves into the interior of the shell 11.

[0044] In this embodiment, multiple microwave feed probes 12 are provided. These multiple microwave feed probes 12 are evenly arranged around the circumference of the housing 11 and located between the inlet and outlet of the microwave reboiler 1. They are used to perform microwave heating on the cold, rich liquid to be desorbed that flows into the housing 11 from the inlet. At least four microwave feed probes 12 are provided to provide a uniform and stable heating environment for the fluid within the housing 11. The heating temperature of the microwave feed probes 12 is set to 86-130°C, the microwave frequency is set to 1500-2500 MHz, and the power is set to 500-900 W.

[0045] In this embodiment, the microwave reboiler 1 further includes a flow guide 13, which is arranged inside the shell 11 and below the inlet of the microwave reboiler 1. The flow guide 13 is connected to an external driving device and rotates under the drive of the external driving device. The flow guide 13 is provided with a plurality of spirally arranged flow grooves for guiding the cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed entering the microwave reboiler 1, so that the cold rich liquid can flow in a spiral streamline along the inner wall of the shell 11. Compared with a vertically falling streamline, this flow form extends the streamline stroke of the fluid, increases the residence time of the fluid in the microwave reboiler 1, and ensures that it can be fully heated.

[0046] In this embodiment, the upper part of the shell 11 is a cylindrical structure, and the lower part is a conical structure with a gradually narrowing inner wall. The deflector 13 of the microwave reboiler 1 is coaxially arranged inside the cylindrical structure of the shell 11. The bottom end of the guide groove of the deflector 13 is connected to the top of the conical structure of the shell 11. The inner wall of the conical structure is provided so that the streamline can always keep in contact with the inner wall while flowing along the spiral. When the cold rich liquid to be desorbed enters the shell 11 from the inlet, it passes through the guide groove to form a spiral streamline gradually downward along the wall of the cone section, as shown in FIG. Figure 2 As shown by the arrowed lines in the figure, the entire desorbed cold rich liquid forms a swirling flow field. This increases the turbulence of the desorbed cold rich liquid, prolonging its residence time within the shell 11 and effectively improving its heating and heat transfer efficiency. Compared to a uniform cylindrical shell 11, this structure reduces the influence of gravity and prevents streamlines from flowing directly down the vertical inner wall under the influence of gravity.

[0047] The deflector 13 includes a rotating shaft and blades. The blades are arranged along a spiral line around the rotating shaft to form a spiral guide groove. In this embodiment, there are at least two blades, so that after being spirally wound, multiple guide grooves are formed. In this embodiment, a first overflow port 111 for overflow is also provided at the top of the housing 11.

[0048] In this embodiment, Figure 3 As shown, the ultrasonic gas-liquid separator 2 includes a housing 24 and ultrasonic vibrators 25. The inlet, gas outlet 22, and liquid outlet 23 of the ultrasonic gas-liquid separator 2 are arranged on the housing 24 in order from top to bottom. The ultrasonic vibrators 25 are mounted on the outer surface of the housing 24 and located between the inlet and gas outlet 22 of the ultrasonic gas-liquid separator 2. They are used to feed ultrasonic vibrations into the housing 24. After the gas-liquid mixture enters the housing 24 through the inlet of the ultrasonic gas-liquid separator 2, the ultrasonic vibrators 25 ultrasonically separate it. In this embodiment, at least four ultrasonic vibrators 25 are provided, with an ultrasonic frequency set to 40kHz to 68kHz and a power set to 500W to 1800W. A second overflow port 241 is also provided at the top of the housing 24 of the ultrasonic gas-liquid separator 2. The inlet and gas outlet 22 of the ultrasonic gas-liquid separator 2 are located at the top of the housing 24, and the liquid outlet 23 is located at the bottom of the housing 24.

[0049] The jacket 21 is wrapped around the outer surface of the shell 24 and is located between the gas outlet 22 and the liquid outlet 23, so as to fully exchange heat during the gas-liquid separation process. The inner width of the jacket 21 is 50mm to 100mm.

[0050] In this embodiment, the ultrasonic gas-liquid separator 2 further includes a first filler 27. This filler 27 is located within the housing 24, corresponding to the position of the ultrasonic oscillator 25, between the inlet and the gas outlet 22 of the ultrasonic gas-liquid separator 2. This filler 27 is used to increase the dispersion of the gas-liquid mixture of hydrogen chloride and chlorosilane as it flows through the first filler 27. The placement of the first filler 27 creates a high porosity, large voids, high flux, and low resistance within this portion of the housing 24, allowing for the free passage of gas and liquid. This ensures good gas and liquid distribution, with liquid sprayed onto the first filler 27 flowing either along its outer or inner walls. This increases liquid dispersion and surface utilization.

[0051] After the first filler 27 is coupled to the ultrasonic vibrator 25 , the movement of microbubbles dissolved in the liquid is further intensified, the gas-liquid contact area and mass transfer flux are increased, and the separation of gas and liquid is promoted.

[0052] In this embodiment, the ultrasonic gas-liquid separator 2 further includes a liquid distributor 26 , which is disposed inside the housing 24 . The top of the liquid distributor 26 is connected to the inlet of the ultrasonic gas-liquid separator 2 , and the bottom of the liquid distributor 26 is divided into multiple branch pipes 261 . Each branch pipe 261 is provided with multiple liquid outlets 262 for connecting the interior of the liquid distributor 26 with the interior of the housing 24 , and spraying the gas-liquid mixture of hydrogen chloride and chlorosilane obtained from the inlet of the ultrasonic gas-liquid separator 2 into the interior of the housing 24 . The liquid outlets 262 face the inner wall of the housing 24 .

[0053] After entering the ultrasonic gas-liquid separator 2, the liquid first passes through the first filler 27 and, after being ultrasonically vibrated by the ultrasonic oscillator 25, enters the liquid distributor 26, achieving the first gas-liquid separation. The liquid then passes through the branch pipe 261 of the liquid distributor 26 and is ejected from the liquid outlet 262, achieving the second gas-liquid separation. Because the liquid outlet 262 faces the inner wall of the housing 24, it allows the fluid to collide with the wall, effectively increasing the fluid's turbulence and achieving the third gas-liquid separation.

[0054] In this embodiment, the bottom of the liquid distributor 26 is divided into at least four branches 261, and each branch 261 is provided with at least eight liquid outlet holes 262. The shape of the hole can be any one of circular, elliptical, diamond, and conical. The distance between the branch 261 and the inner wall of the ultrasonic gas-liquid separator 2 is set to 20 cm to 50 cm.

[0055] In this embodiment, a gap exists between the liquid distributor 26 and the housing 24. The ultrasonic gas-liquid separator 2 also includes a second filler 28, which is placed between the housing 24 and the liquid distributor 26, below the gas outlet 22 and above each liquid outlet 262. This filler 28 is used to filter out chlorosilanes from the hot hydrogen chloride gas after gas-liquid separation. When the hydrogen chloride gas carrying some chlorosilane liquid is about to flow out of the gas outlet 22, it is further filtered by the second filler 28, achieving a fourth gas-liquid separation. Through the action of the two-stage filler, the ultrasonic vibrator 25, and the liquid distributor 26, the degree of gas-liquid separation gradually increases, ensuring a satisfactory desorption effect.

[0056] In this embodiment, both the first filler 27 and the second filler 28 are packed in bulk, with a wire mesh plate positioned at the bottom. This wire mesh plate has a conventional commercially available structure and is not described in detail here. The first and second fillers 27 and 28 can be constructed from any of the following: metal ball rings, metal step rings, metal saddle rings, metal Nutter rings, and metal 84 inner arc rings, with their dimensions larger than the aperture of the wire mesh plate used to hold the filler.

[0057] In this embodiment, in order to further increase the degree of collision between the liquid and the inner wall of the shell 24 and intensify the gas-liquid separation, the inner wall of the shell 24 is provided with folds with a sawtooth cross-section.

[0058] In this embodiment, the primary cold rich liquid is composed of 45% tetrachlorosilane, 53% trichlorosilane and 2% dichlorosilane, and the temperature is -40°C. The speed of pump 5 is set to 2900 rpm, and the processing capacity of the cold rich liquid is 40m3. 3 / h. Four microwave feed probes 12 are provided in the microwave reboiler 1; four ultrasonic vibrators 25 are provided in the ultrasonic gas-liquid separator 2, with an ultrasonic frequency of 50 kHz and a power of 800 W. Metal ball rings are used for the first and second fillers 27 and 28. The liquid distributor 26 has four branch pipes 261, each with eight liquid outlet holes 262 formed in a circular shape. The distance between the branch pipes 261 and the inner wall of the ultrasonic gas-liquid separator 2 is set to 25 cm. The inner width of the jacket 21 is 80 mm. Tubular heat exchangers are used for both the condenser 3 and the heat exchanger 4.

[0059] The desorption process of hydrogen chloride (HCl) from polysilicon reduction tail gas treated by this equipment was compared with that of a conventional desorption tower. Assuming the same primary cold rich liquid throughput and meeting the HCl desorption target, the conventional desorption method requires approximately 4.6 GJ / t HCl of desorption energy. By varying the set temperature of microwave reboiler 1, the desorption energy required by this equipment was calculated, as shown in Table 1:

[0060] Table 1 Comparison of desorption energy consumption between traditional desorption equipment and this equipment

[0061]

[0062] As can be seen, compared with conventional desorption equipment, the desorption energy consumption of this device can be reduced by 69.6% when the microwave temperature is set to 90°C. According to this embodiment, the desorption energy consumption of this device can also be adjusted by adjusting parameters such as ultrasonic power, microwave and ultrasonic vibrator 25, the structure of liquid distributor 26 in ultrasonic gas-liquid separator 2, and the internal width of jacket 21.

[0063] Example 2

[0064] The polysilicon production system of this embodiment includes a bell jar reactor and an absorption tower, and also includes the polysilicon reduction tail gas hydrogen chloride desorption device in Example 1. The bell jar reactor, the absorption tower and the polysilicon reduction tail gas hydrogen chloride desorption device are connected in sequence. The absorption tower absorbs and separates the hydrogen chloride gas discharged from the bell jar reactor through chlorosilane liquid to obtain a cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed in the polysilicon reduction tail gas. The polysilicon reduction tail gas hydrogen chloride desorption device desorbs the cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed discharged from the absorption tower. The desorption process can effectively improve the desorption efficiency, reduce energy consumption, and improve heat utilization. Therefore, the production efficiency and energy utilization of the entire production system are also effectively improved.

[0065] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A polysilicon reduction tail gas hydrogen chloride desorption device, characterized by: The invention comprises a microwave reboiler (1), an ultrasonic gas-liquid separator (2), a condenser (3), a heat exchanger (4) and a pump (5). The outer wall of the ultrasonic gas-liquid separator (2) is provided with a jacket (21), and the jacket (21) is a hollow structure. The microwave reboiler (1) is used to perform microwave heating on the cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed to form a gas-liquid mixture of hydrogen chloride and chlorosilane. The outlet of the microwave reboiler (1) is connected to the inlet of the ultrasonic gas-liquid separator (2). The ultrasonic gas-liquid separator (2) is used to ultrasonically separate the gas-liquid mixture. The gas outlet (22) of the ultrasonic gas-liquid separator (2) is connected to the condenser (3), and the liquid outlet (23) of the ultrasonic gas-liquid separator (2) is connected to the heat exchanger (4). The hot hydrogen chloride gas and the hot chlorosilane lean liquid obtained after ultrasonic separation are respectively introduced into the condenser (3) and the heat exchanger (4). The outlet of the pump (5) is connected to the condenser (3), the heat exchanger (4) and the jacket (21) in series through a pipeline, and then connected to the inlet of the microwave reboiler (1). The chlorosilane containing hydrogen chloride in the polysilicon reduction tail gas, i.e., the primary cold rich liquid, is driven by a pump (5) to flow, and is condensed in the condenser (3) by condensing the hot hydrogen chloride gas in the condenser (3) to obtain a first-stage cold rich liquid; the first-stage cold rich liquid enters the heat exchanger (4) and exchanges heat with the chlorosilane hot lean liquid in the heat exchanger (4) to obtain a second-stage cold rich liquid; the second-stage cold rich liquid enters the jacket (21) and exchanges heat with the gas-liquid mixture in the ultrasonic gas-liquid separator (2) to obtain a third-stage cold rich liquid; the third-stage cold rich liquid heated by the third-stage heat exchange is introduced into the microwave reboiler (1) as the chlorosilane cold rich liquid containing hydrogen chloride to be desorbed, so as to reduce the microwave heating output.

2. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 1, characterized in that: The microwave reboiler (1) comprises a housing (11) and a microwave feeding probe (12). The inlet of the microwave reboiler (1) is arranged at the upper part of the shell (11), and the outlet of the microwave reboiler (1) is arranged at the bottom of the shell (11). The microwave feeding probe (12) is arranged on the outer surface of the shell (11) and is used to feed microwaves into the interior of the shell (11).

3. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 2, characterized in that: The microwave reboiler (1) further comprises a flow guide (13), which is arranged inside the shell (11) and below the inlet of the microwave reboiler (1). The deflector (13) is connected to an external driving device and rotates under the drive of the external driving device. The deflector (13) is provided with a plurality of spirally arranged deflection grooves for guiding the cold rich liquid of chlorosilane containing hydrogen chloride to be desorbed entering the microwave reboiler (1).

4. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 3, characterized in that: The lower portion of the shell (11) is a conical structure with a gradually narrowing inner wall, and the bottom end of the guide groove of the deflector (13) is connected to the top end of the conical structure of the shell (11).

5. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 1, characterized in that: The ultrasonic gas-liquid separator (2) comprises a housing (24) and an ultrasonic vibrator (25). The inlet, gas outlet (22) and liquid outlet (23) of the ultrasonic gas-liquid separator (2) are arranged on the housing (24) in sequence from top to bottom. The ultrasonic vibrator (25) is mounted on the outer surface of the housing (24) and is located between the inlet and the gas outlet (22) of the ultrasonic gas-liquid separator (2), and is used to feed ultrasonic vibration into the housing (24).

6. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 5, characterized in that: The ultrasonic gas-liquid separator (2) further comprises a first filler (27), The first filler (27) is filled inside the housing (24) corresponding to the position of the ultrasonic vibrator (25), and is located between the inlet and the gas outlet (22) of the ultrasonic gas-liquid separator (2), and is used to increase the dispersion of the gas-liquid mixture of hydrogen chloride and chlorosilane when it flows through the first filler (27).

7. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 5, characterized in that: The ultrasonic gas-liquid separator (2) further comprises a liquid distributor (26), The liquid distributor (26) is arranged inside the housing (24), the top of which is connected to the inlet of the ultrasonic gas-liquid separator (2), and the bottom of which is divided into multiple branch pipes (261). Each branch pipe (261) is provided with a plurality of liquid outlet holes (262) for connecting the interior of the liquid distributor (26) and the interior of the housing (24), and spraying the gas-liquid mixture of hydrogen chloride and chlorosilane obtained from the inlet of the ultrasonic gas-liquid separator (2) into the interior of the housing (24).

8. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 7, characterized in that: There is a gap between the liquid distributor (26) and the housing (24), and the ultrasonic gas-liquid separator (2) further includes a second filler (28). The second filler (28) is filled between the shell (24) and the liquid distributor (26), and is located below the gas outlet (22) and above each liquid outlet hole (262), and is used to filter out chlorosilane in the hot hydrogen chloride gas after gas-liquid separation.

9. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 7, characterized in that: The liquid outlet hole (262) faces the inner wall of the outer shell (24).

10. The polysilicon reduction tail gas hydrogen chloride desorption equipment according to claim 5, characterized in that: The inner wall of the outer shell (24) is provided with folds having a sawtooth-shaped cross section.

11. A polysilicon production system comprising a bell jar reactor and an absorption tower, characterized in that: It also includes a desorption device for hydrogen chloride from the polysilicon reduction tail gas according to any one of claims 1 to 10, wherein the bell jar reactor, the absorption tower and the desorption device for hydrogen chloride from the polysilicon reduction tail gas are connected in sequence. The absorption tower absorbs and separates the hydrogen chloride gas discharged from the bell-jar reactor through chlorosilane liquid to obtain a cold rich chlorosilane liquid containing hydrogen chloride to be desorbed from the polysilicon reduction tail gas. The polysilicon reduction tail gas hydrogen chloride desorption equipment desorbs the cold rich chlorosilane liquid containing hydrogen chloride to be desorbed from the absorption tower.

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