Polycrystalline silicon industrial waste gas recycling system

Abstract

The utility model provides a polycrystalline silicon industrial waste gas recycling system. The polycrystalline silicon industrial waste gas recycling system comprises a tail gas buffer tank, a condenser, a front tail gas buffer tank, a compressor and a rear tail gas buffer tank, the tail gas buffer tank is communicated with a tail gas emptying main pipeline and is used for inputting tail gas; the input end of the condenser is communicated with the upper part of the tail gas buffer tank through an exhaust pipeline and is used for condensing tail gas input by the tail gas buffer tank and conveying residual non-condensable gas to the tail gas front buffer tank through a non-condensable gas pipeline; the compressor is communicated between the tail gas front buffer tank and the tail gas rear buffer tank and is used for compressing gas in the tail gas front buffer tank into the tail gas rear buffer tank; the tail gas rear buffer tank is further communicated with a nitrogen output pipeline used for outputting nitrogen. According to the utility model, the nitrogen consumption in the polycrystalline silicon production process is reduced, the public and auxiliary cost of operation is reduced, the tail gas is secondarily recycled, the tail gas treatment load is reduced, the generation of hydrolysis waste gas and the harm to the environment are reduced, and the production cost is saved.

Description

Technical Field

[0001] This utility model belongs to the field of polysilicon industrial technology, specifically illustrating a polysilicon industrial waste gas recovery and utilization system. Background Technology

[0002] During the production of polysilicon, a large amount of waste gas and slurry are generated. The waste gas contains chlorosilanes and silicon powder, while the slurry is mainly composed of about 5% solid phase components (silicon powder particles) and about 95% liquid phase components (chlorosilanes, high-boiling substances, and others), of which chlorosilane liquid components account for more than 90%.

[0003] Currently, such as Figure 1 As shown, the process flow for waste gas treatment in the polysilicon industry is as follows:

[0004] (1) In the original process, the tail gas is vented and enters the tail gas buffer tank 1 through the tail gas venting main pipe 101. The tail gas in the tail gas buffer tank enters the first-stage condenser 2 and the second-stage condenser 5 through the exhaust pipe 102. The generated chlorosilane condensate enters the condensate tank 3 through the condensate pipe 202. The chlorosilane liquid in the condensate tank 3 enters the recovery pump 4 through the recovery pipe 301 and is transported to the chlorosilane recovery device (not shown in this application) through the external delivery pipe 401.

[0005] (2) The non-condensable gas condensed by the primary condenser 2 and the secondary condenser 5 enters the dynamic wave mixer 6 through the non-condensable gas pipelines 501 and 504 to undergo preliminary acid-base neutralization with the alkaline solution, and then enters the tail gas scrubbing tower 7. The tail gas scrubbing tower 7 is equipped with a spray system at the top. The generated waste liquid is circulated or sent out through the circulation pump 8 of the tail gas scrubbing tower 7. Part of the circulating waste liquid is used as the spray liquid for the dynamic wave mixer 6 and the tail gas scrubbing tower 7, and part of it is transported to the sewage treatment device (not shown in this application) through pipeline 801 for further treatment. The waste gas generated in the tail gas scrubbing tower 7 is fully absorbed by the liquid seal in the liquid seal tank 9 and discharged after meeting the standards. The generated waste liquid is returned to the tail gas scrubbing tower 7 through pipeline 902.

[0006] (3) Liquid seal water supply pipe 901 replenishes fresh water and / or alkali solution to liquid seal tank 9, and washing tower water supply pipe 702 replenishes fresh water and / or alkali solution to tail gas washing tower 7 to maintain the liquid level and pH value of tail gas treatment device.

[0007] However, during the production process of polysilicon plants, the nitrogen charging and depressurization, system replacement, and other operations required to maintain system operation result in high nitrogen demand and high operating costs. The exhaust gas emitted from tail gas scrubbing tower 7 is mainly nitrogen, and the large amount of nitrogen emitted leads to waste, increases the load on the nitrogen preparation unit, and raises production costs. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a polysilicon industrial waste gas recovery and utilization system, which reduces the amount of nitrogen used in the polysilicon production process, reduces operating auxiliary costs, and at the same time, allows for secondary recovery and utilization of tail gas, reduces the tail gas treatment load, reduces the generation of hydrolysis waste gas and its harm to the environment, and saves production costs.

[0009] To achieve the above objectives / to solve the above technical problems, this utility model adopts the following technical solution:

[0010] This utility model provides a polysilicon industrial waste gas recovery and utilization system, including a tail gas buffer tank, a condenser, a tail gas pre-buffer tank, a compressor, and a tail gas post-buffer tank.

[0011] The exhaust gas buffer tank is connected to an exhaust gas venting main pipe for inputting exhaust gas.

[0012] The input end of the condenser is connected to the upper part of the exhaust gas buffer tank through an exhaust pipe, which is used to condense the exhaust gas input into the exhaust gas buffer tank and transport the remaining non-condensable gas to the exhaust gas front buffer tank through a non-condensable gas pipe.

[0013] The compressor is connected between the exhaust gas front buffer tank and the exhaust gas rear buffer tank, and is used to compress the gas in the exhaust gas front buffer tank into the exhaust gas rear buffer tank.

[0014] The exhaust gas buffer tank is also connected to a nitrogen output pipe for outputting nitrogen.

[0015] The above setup achieves the following effects: the condenser filters impurities in the exhaust gas from the exhaust gas buffer tank. The non-condensable gas after condensation is mainly nitrogen (content above 98%), along with small amounts of hydrogen and trace amounts of chlorosilanes. After passing through the non-condensable gas pipeline, a portion of the non-condensable gas is introduced into the exhaust gas pre-buffer tank before the compressor. By setting up the exhaust gas pre-buffer tank, compressor, and exhaust gas post-buffer tank, the nitrogen in the exhaust gas is filtered, compressed, and stored. It can then be output through the nitrogen output pipeline. The exhaust gas, pressurized in the exhaust gas post-buffer tank, is transported to downstream process units through the nitrogen output pipeline for use, replacing fresh nitrogen as the pressurization, stabilization, and safe emission gas for the production system.

[0016] Furthermore, a valve is installed on the nitrogen output pipeline.

[0017] The above setup achieves the following effect: the rate and quantity of nitrogen output can be controlled by adjusting the valve on the nitrogen output pipeline.

[0018] Furthermore, the system also includes a condensate tank;

[0019] The liquid output end of the condenser is connected to the condensate tank via a condensate pipe; the exhaust gas buffer tank is connected to the condensate tank via a drain pipe.

[0020] The exhaust gas pre-buffer tank is equipped with a gas inlet, which is connected to the non-condensable gas pipeline through the pre-buffer tank inlet pipe.

[0021] Both the pre-exhaust gas buffer tank and the post-exhaust gas buffer tank are equipped with liquid outlets at their bottoms; the liquid outlets of the pre-exhaust gas buffer tank and the post-exhaust gas buffer tank are connected to the condensate tank via liquid outlet pipes.

[0022] The above setup achieves the following effect: liquid deposition of gas is achieved through the pre-exhaust gas buffer tank and the post-exhaust gas buffer tank, removing chlorosilanes from the exhaust gas, and the liquid is output to the condensate tank through the liquid output terminal.

[0023] Furthermore, the exhaust gas pre-buffer tank is connected to the condensate tank via a pre-liquid outlet pipe; the exhaust gas post-buffer tank is connected to the pre-liquid outlet pipe via a post-liquid outlet pipe.

[0024] Valves are installed on both the front liquid output pipe and the rear liquid output pipe.

[0025] The above setup achieves the following effect: by controlling the quantity and rate at which liquid is delivered from the pre-exhaust gas buffer tank and the post-exhaust gas buffer tank to the condensate tank via valves, it is easier to adjust the liquid recovery efficiency.

[0026] Furthermore, the bottom of the condensate tank is connected to a recovery pump via a recovery pipe, the recovery pump being used to transport the liquid from the condensate tank to the outside to recover silicon chloride.

[0027] The above setup achieves the following effects: the chlorosilane condensate in the pre-buffer tank is collected in the condensate tank through the pre-liquid output pipe, the chlorosilane condensate in the post-buffer tank is collected in the condensate tank through the post-liquid output pipe and the pre-liquid output pipe, the condensate in the condensate tank is collected in the condensate tank through the recovery pipe to the recovery pump, and then transported to the chlorosilane recovery device through the external transmission pipe.

[0028] Furthermore, the exhaust gas pre-buffer tank and the exhaust gas post-buffer tank are connected by a return pipe, and a return regulating valve is installed on the return pipe.

[0029] The above settings achieve the following effect: the pressure of the exhaust gas pre-buffer tank and exhaust gas post-buffer tank is adjusted by the reflux regulating valve. When the pressure of the exhaust gas pre-buffer tank is high or the pressure of the exhaust gas pre-buffer tank is too low, the reflux regulating valve is opened and the gas returns to the exhaust gas pre-buffer tank through the reflux pipeline.

[0030] Furthermore, the system also includes an exhaust gas scrubbing subsystem;

[0031] The exhaust gas scrubbing subsystem is connected to the non-condensable gas pipeline via a check valve, thereby receiving gas from the non-condensable gas pipeline in one direction for exhaust gas scrubbing.

[0032] The above setup achieves the following effect: Through the check valve, the exhaust gas scrubbing subsystem receives gas from the non-condensable gas pipeline in one direction for exhaust gas scrubbing, which facilitates the treatment of gases with more impurities, can also share the exhaust gas treatment pressure, and speed up the treatment rate.

[0033] Furthermore, the upper part of the exhaust gas buffer tank is connected to the exhaust gas washing subsystem via a washing pipe; a washing valve is installed on the washing pipe.

[0034] The above settings achieve the following effect: when the reflux regulating valve is not adjusted in time or the pressure of the exhaust gas pre-buffer tank is high, the washing valve can also be opened to transport the exhaust gas through the washing pipeline and the washing input pipeline to the power wave mixer for neutralization treatment.

[0035] Furthermore, the system also includes a gas detector installed on the exhaust gas after buffer tank, used to analyze the oxygen content and / or dew point of the gas in the exhaust gas after buffer tank and output the results for display.

[0036] The gas detector will sound an alarm when the oxygen content and / or dew point of the gas in the exhaust gas buffer tank exceeds the preset value.

[0037] Furthermore, the washing valve is an electrically controlled valve, which is electrically connected to the gas detector; when the oxygen content and dew point of the gas in the exhaust gas buffer tank exceed the preset value, the gas detector controls the washing valve to open.

[0038] The above setup achieves the following effect: An AI001 gas detector for online detection of oxygen content and dew point is installed in the exhaust gas buffer tank. When the oxygen content is >50PPM and the dew point is >-40℃, the scrubbing valve is opened, and the exhaust gas is transported to the exhaust gas scrubbing subsystem for neutralization treatment through the scrubbing pipeline and the scrubbing input pipeline.

[0039] Furthermore, the system also includes a pressure detector installed on the exhaust gas after buffer tank, used to collect the gas pressure in the exhaust gas after buffer tank and output and display it.

[0040] Furthermore, both the washing valve and the reflux regulating valve are electrically controlled valves;

[0041] The pressure detector is electrically connected to the washing valve and the reflux regulating valve respectively, and is used to control the opening and closing of the washing valve and the reflux regulating valve according to the gas pressure in the exhaust gas buffer tank.

[0042] The above settings achieve the following effect: the pressure of the exhaust gas pre-buffer tank and exhaust gas post-buffer tank is adjusted by the reflux regulating valve. When the pressure of the exhaust gas post-buffer tank collected by the pressure detector is high or the pressure of the exhaust gas pre-buffer tank is too low, the reflux regulating valve is opened and the gas returns to the exhaust gas pre-buffer tank through the reflux pipeline.

[0043] When the reflux regulating valve is not adjusted in time or the pressure of the exhaust gas pre-buffer tank is high, the washing valve can also be opened to send the washing pipeline and washing input pipeline to the exhaust gas washing subsystem for neutralization treatment.

[0044] Furthermore, the condenser includes a primary condenser and a secondary condenser that are connected in series;

[0045] Both the primary condenser and the secondary condenser are equipped with a gas inlet, a gas outlet, and a liquid outlet.

[0046] The gas output end of the first-stage condenser is connected to the upper part of the tail gas buffer tank through the exhaust pipe; the gas output end of the first-stage condenser is connected to the gas input end of the second-stage condenser through pipe one; the gas output end of the second-stage condenser is connected to the tail gas pre-buffer tank through the non-condensable gas pipe; the liquid output ends of the first-stage condenser and the liquid output ends of the second-stage condenser are both connected to the condensate tank through condensate pipes.

[0047] Furthermore, the exhaust gas scrubbing subsystem includes a power wave mixer, an exhaust gas scrubbing tower, a circulating pump, and a liquid seal tank.

[0048] The dynamic wave mixer is connected to the non-condensable gas pipeline through the washing input pipeline and the check valve, thereby obtaining the exhaust gas to be treated;

[0049] The gas enters the dynamic wave mixer and undergoes preliminary acid-base neutralization with the alkaline solution, and then enters the tail gas scrubbing tower through pipeline three. The tail gas scrubbing tower is equipped with a spray system at the top.

[0050] The waste liquid generated in the tail gas scrubbing tower is circulated or sent out through the circulating pump of the tail gas scrubbing tower. Part of the circulating waste liquid is used as a dynamic wave mixer through pipes six and seven, part of it is used as spray liquid in the tail gas scrubbing tower through pipes six and eight, and another part is transported to the sewage treatment device (not shown in this application) through pipe five for further treatment. The waste gas generated in the tail gas scrubbing tower is fully absorbed by the liquid seal in the liquid seal tank and discharged after meeting the standards. The waste liquid generated is returned to the tail gas scrubbing tower through pipe nine.

[0051] The liquid seal tank is connected to a liquid seal water supply pipe, which replenishes the liquid seal tank with fresh water and / or alkaline solution.

[0052] The exhaust gas scrubbing tower is connected to a water supply pipe; the water supply pipe replenishes the exhaust gas scrubbing tower with fresh water and / or alkaline solution to maintain the liquid level and pH value of the exhaust gas treatment device.

[0053] Compared with the prior art, the beneficial effects achieved by this utility model are as follows:

[0054] 1. This patent provides a novel production method for recycling and utilizing waste gas in the polysilicon industry. This application mainly reduces the amount of nitrogen used in the polysilicon production process, reduces operating auxiliary costs, and at the same time, it enables secondary recycling and utilization of tail gas, reduces the tail gas treatment load, reduces the generation of hydrolysis waste gas and its harm to the environment, and saves production costs.

[0055] 2. Compared with traditional methods, nitrogen can be recovered and used as a pressurizing, stabilizing, and safety protection gas for other devices, reducing the amount of fresh nitrogen used and lowering the cost of nitrogen production for operating auxiliary facilities;

[0056] 3. Process exhaust gas is recycled to reduce the generation of hydrolysis waste gas and its harm to the environment;

[0057] 4. The amount of exhaust gas produced is less than that of enterprises with the same production scale, thus reducing the investment in exhaust gas treatment equipment. Attached Figure Description

[0058] Figure 1 This is a structural diagram of existing technology;

[0059] Figure 2 This is a schematic diagram of the structure of this utility model.

[0060] In the diagram: 1. Exhaust gas buffer tank; 101. Exhaust gas vent main pipe; 102. Exhaust pipe; 103. Drain pipe; 2. First-stage condenser; 201. Pipeline 1; 202. Condensate pipe; 3. Condensate tank; 301. Recovery pipe; 4. Recovery pump; 401. External delivery pipe; 5. Second-stage condenser; 501. Non-condensable gas pipe; 502. Pre-buffer tank inlet pipe; 503. Pipeline 2; 504. Check valve; 505. Scrubber input pipe; 6. Power wave mixer; 601. Pipeline 3; 7. Exhaust gas scrubber; 701. Pipeline 4; 702. Scrubber makeup water. Pipeline; 8. Circulation pump; 801. Pipeline 5; 802. Pipeline 6; 803. Pipeline 7; 804. Pipeline 8; 9. Liquid seal tank; 901. Liquid seal water supply pipeline; 902. Pipeline 9; 10. Exhaust gas pre-buffer tank; 1001. Pre-liquid output pipeline; 11. Compressor; 12. Exhaust gas post-buffer tank; 1201. Post-liquid output pipeline; 1202. Return pipeline; 1203. Return regulating valve; 1204. Washing pipeline; 1205. Washing valve; 1206. Nitrogen output pipeline; AI001. Gas detector; PI001. Pressure detector. Detailed Implementation

[0061] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0062] In the description of this embodiment, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment. Example 1

[0063] This embodiment provides a polysilicon industrial waste gas recovery and utilization system, such as... Figure 2 As shown, the system includes an exhaust gas buffer tank 1, a condenser, an exhaust gas pre-buffer tank 10, a compressor 11, and an exhaust gas post-buffer tank 12. The exhaust gas buffer tank 1 is connected to an exhaust gas vent pipe 101 for inputting exhaust gas. The input end of the condenser is connected to the upper part of the exhaust gas buffer tank 1 via an exhaust pipe 102, for condensing the exhaust gas input into the exhaust gas buffer tank 1 and transporting the remaining non-condensable gas to the exhaust gas pre-buffer tank 10 via a non-condensable gas pipe 501. The compressor 11 is connected between the exhaust gas pre-buffer tank 10 and the exhaust gas post-buffer tank 12, for compressing the gas in the exhaust gas pre-buffer tank 10 into the exhaust gas post-buffer tank 12. The exhaust gas post-buffer tank 12 is also connected to a nitrogen output pipe 1206 for outputting nitrogen.

[0064] Implementation principle: The condenser filters impurities in the tail gas from the tail gas buffer tank 1. The non-condensable gas after condensation is mainly nitrogen (content above 98%), a small amount of hydrogen, and trace amounts of chlorosilane. After passing through the non-condensable gas pipeline 501, a portion of the non-condensable gas is introduced into the tail gas pre-buffer tank 10 before the compressor 11. By setting up the tail gas pre-buffer tank 10, the compressor 11, and the tail gas post-buffer tank 12, the nitrogen in the tail gas is filtered, compressed, and stored. It can be output through the nitrogen output pipeline 1206. The tail gas, after being pressurized in the tail gas post-buffer tank 12, is transported to downstream process units through the nitrogen output pipeline 1206 for use, replacing fresh nitrogen as the pressurization, stabilization, and safe emission gas of the production system. Example 2

[0065] Based on a design principle similar to that of Example 1, this embodiment provides a polycrystalline silicon industrial waste gas recovery and utilization system, such as... Figure 2As shown, it includes an exhaust gas buffer tank 1, a primary condenser 2, a secondary condenser 5, an exhaust gas pre-buffer tank 10, a compressor 11, an exhaust gas post-buffer tank 12, a condensate tank 3, and an exhaust gas scrubbing subsystem.

[0066] The exhaust gas buffer tank 1 is connected to the exhaust gas venting main pipe 101 for inputting exhaust gas.

[0067] The input end of the condenser is connected to the upper part of the exhaust gas buffer tank 1 through the exhaust pipe 102, which is used to condense the exhaust gas input into the exhaust gas buffer tank 1, and to transport the remaining non-condensable gas to the exhaust gas front buffer tank 10 through the non-condensable gas pipe 501.

[0068] The compressor 11 is connected between the exhaust gas front buffer tank 10 and the exhaust gas rear buffer tank 12, and is used to compress the gas in the exhaust gas front buffer tank 10 into the exhaust gas rear buffer tank 12.

[0069] The exhaust gas buffer tank 12 is also connected to a nitrogen output pipe 1206 for outputting nitrogen.

[0070] Impurities in the exhaust gas from the exhaust gas buffer tank 1 are filtered by a condenser. The non-condensable gas after condensation is mainly nitrogen (content above 98%), a small amount of hydrogen, and trace amounts of chlorosilane. After passing through the non-condensable gas pipeline 501, a portion of the non-condensable gas is introduced into the exhaust gas pre-buffer tank 10 before the compressor 11. By setting up the exhaust gas pre-buffer tank 10, the compressor 11, and the exhaust gas post-buffer tank 12, the nitrogen in the exhaust gas is filtered, compressed, and stored. It can be output through the nitrogen output pipeline 1206. The exhaust gas, after being pressurized in the exhaust gas post-buffer tank 12, is transported to downstream process units through the nitrogen output pipeline 1206 for use, replacing fresh nitrogen as the pressurization, stabilization, and safe emission gas for the production system.

[0071] Preferably, a valve is installed on the nitrogen output pipe 1206. The rate and quantity of nitrogen output can be adjusted by the valve on the nitrogen output pipe 1206.

[0072] The liquid outlet of the condenser is connected to the condensate tank 3 via condensate pipe 202; the tail gas buffer tank 1 is connected to the condensate tank 3 via drain pipe 103; the tail gas pre-buffer tank 10 is equipped with a gas inlet, which is connected to the non-condensable gas pipeline via the pre-buffer tank inlet pipe 502; both the tail gas pre-buffer tank 10 and the tail gas post-buffer tank 12 have liquid outlets at their bottoms; the liquid outlets of the tail gas pre-buffer tank 10 and the tail gas post-buffer tank 12 are connected to the condensate tank 3 via liquid outlet pipes. Liquid deposition of the gas is performed through the tail gas pre-buffer tank 10 and the tail gas post-buffer tank 12 to remove chlorosilanes from the tail gas, and the gas is then output to the condensate tank 3 via the liquid outlet.

[0073] The exhaust gas pre-buffer tank 10 is connected to the condensate tank 3 via a pre-liquid output pipe 1001; the exhaust gas post-buffer tank 12 is connected to the pre-liquid output pipe 1001 via a post-liquid output pipe 1201; both the pre-liquid output pipe 1001 and the post-liquid output pipe 1201 are equipped with valves. The quantity and rate of liquid delivered from the exhaust gas pre-buffer tank 10 and the exhaust gas post-buffer tank 12 to the condensate tank 3 are controlled by the valves, facilitating the adjustment of liquid recovery efficiency.

[0074] The bottom of the condensate tank 3 is connected to a recovery pump 4 via a recovery pipe 301. The recovery pump 4 is used to transport the liquid from the condensate tank 3 to the outside to recover silicon chloride.

[0075] The exhaust gas front buffer tank 10 and the exhaust gas rear buffer tank 12 are connected by a return pipe 1202, and a return regulating valve 1203 is installed on the return pipe 1202.

[0076] Specifically, the exhaust gas scrubbing subsystem is connected to the non-condensable gas pipeline 501 via a check valve 504, thereby unidirectionally receiving gas from the non-condensable gas pipeline 501 for exhaust gas scrubbing. The check valve 504 allows the exhaust gas scrubbing subsystem to unidirectionally receive gas from the non-condensable gas pipeline 501 for exhaust gas scrubbing, facilitating the treatment of gases with high impurity levels, and also reducing exhaust gas processing pressure and accelerating the processing rate.

[0077] The upper part of the exhaust gas buffer tank 12 is also connected to the exhaust gas washing subsystem through a washing pipe 1204; a washing valve 1205 is installed on the washing pipe 1204.

[0078] Preferably, the system also includes a gas detector AI001 installed on the exhaust gas after buffer tank 12, which is used to analyze the oxygen content and dew point of the gas in the exhaust gas after buffer tank 12 and output the results for display; when the oxygen content and dew point of the gas in the exhaust gas after buffer tank 12 exceed the preset values, the gas detector AI001 will sound an alarm.

[0079] Preferably, the washing valve 1205 is an electrically controlled valve, which is electrically connected to the gas detector AI001; when the oxygen content and dew point of the gas in the exhaust gas buffer tank 12 exceed the preset value, the gas detector AI001 controls the washing valve 1205 to open.

[0080] The system also includes a pressure detector PI001 installed on the exhaust gas after buffer tank 12, which is used to collect the gas pressure in the exhaust gas after buffer tank 12 and output and display it.

[0081] Preferably, both the pressure detector PI001 and the gas detector AI001 are real-time detectors available on the market, which are easy to use, provide accurate data, and allow for the free setting of warning standards and the output of alarm and control signals.

[0082] Preferably, both the washing valve 1205 and the reflux regulating valve 1203 are electrically controlled valves; the pressure detector PI001 is electrically connected to the washing valve 1205 and the reflux regulating valve 1203 respectively, and is used to control the opening and closing of the washing valve 1205 and the reflux regulating valve 1203 according to the gas pressure in the exhaust gas buffer tank 12.

[0083] Specifically, the condenser includes a primary condenser 2 and a secondary condenser 5 connected in series; both the primary condenser 2 and the secondary condenser 5 are provided with a gas inlet, a gas outlet, and a liquid outlet; the gas outlet of the primary condenser 2 is connected to the upper part of the exhaust gas buffer tank 1 through an exhaust pipe 102, and the gas outlet of the primary condenser 2 is connected to the gas inlet of the secondary condenser 5 through a pipe 201; the gas outlet of the secondary condenser 5 is connected to the exhaust gas pre-buffer tank 10 through a non-condensable gas pipe 501; the liquid outlets of both the primary condenser 2 and the secondary condenser 5 are connected to the condensate tank 3 through a condensate pipe 202.

[0084] Specifically, the exhaust gas scrubbing subsystem includes a dynamic wave mixer 6, an exhaust gas scrubbing tower 7, a circulating pump 8, and a liquid seal tank 9. The dynamic wave mixer 6 is connected to the non-condensable gas pipeline 501 through the scrubbing input pipeline 505 and the check valve 504, thereby obtaining the exhaust gas to be treated. The gas enters the dynamic wave mixer 6 and undergoes preliminary acid-base neutralization with the alkaline solution, and then enters the exhaust gas scrubbing tower 7 through the pipeline 601. The exhaust gas scrubbing tower 7 is equipped with a spray system at the top.

[0085] The waste liquid generated in the tail gas scrubbing tower 7 is circulated or sent out through the circulation pump 8 of the tail gas scrubbing tower 7. Part of the circulated waste liquid is used as the power wave mixer 6 through pipes 6 802 and 7 803, part of it is used as the spray liquid for the tail gas scrubbing tower 7 through pipes 6 802 and 8 804, and the rest is transported to the sewage treatment plant (not shown in this application) through pipe 5 801 for further treatment. The waste gas generated in the tail gas scrubbing tower 7 is fully absorbed by the liquid seal in the liquid seal tank 9 and discharged after meeting the standards. The waste liquid generated is returned to the tail gas scrubbing tower 7 through pipe 9 902.

[0086] A liquid seal water supply pipe 901 is connected to the liquid seal tank 9. The liquid seal water supply pipe 901 replenishes the liquid seal tank 9 with fresh water and / or alkaline solution.

[0087] The exhaust gas scrubbing tower 7 is connected to a scrubbing tower water supply pipe 702; the scrubbing tower water supply pipe 702 replenishes the exhaust gas scrubbing tower 7 with fresh water and / or alkaline solution to maintain the liquid level and pH value of the exhaust gas treatment device.

[0088] In practical use, the vented exhaust gas emitted from the production unit enters the exhaust gas buffer tank 1 through the exhaust gas venting main pipe 101. The exhaust gas in the exhaust gas buffer tank enters the first-stage condenser 2 and the second-stage condenser 5 through the exhaust pipe 102. The generated chlorosilane condensate enters the condensate tank 3 through the condensate pipe 202. The chlorosilane liquid in the condensate tank 3 enters the recovery pump 4 through the recovery pipe 301, and is transported to the chlorosilane recovery device (not shown in this application) through the external delivery pipe 401.

[0089] The non-condensable gas after condensation by the primary condenser 2 and the secondary condenser 5 is mainly nitrogen (content above 98%), as well as a small amount of hydrogen and trace amounts of chlorosilane. After passing through the non-condensable gas pipeline 501, part of the non-condensable gas enters the tail gas washing subsystem through pipeline 503, check valve 504 and washing input pipeline 505, while the other part is introduced into the tail gas pre-buffer tank 10 of the compressor 11 through pipeline 502.

[0090] The exhaust gas in the pre-exhaust gas buffer tank 10 is compressed by the compressor 11 and then into the post-exhaust gas buffer tank 12. The pressure of the post-exhaust gas buffer tank 12 is measured by PI001 and regulated by the reflux regulating valve 1203 and the washing valve 1205.

[0091] An online oxygen content and dew point detector AI001 is installed in the exhaust gas buffer tank 12. When the oxygen content is >50PPM and the dew point is >-40℃, the washing valve 1205 is opened, and the exhaust gas is transported to the power wave mixer 6 through the washing pipe 1204 and the washing input pipe 505 for neutralization treatment.

[0092] The pressure of the exhaust gas pre-buffer tank 10 and exhaust gas post-buffer tank 12 is adjusted by the reflux regulating valve 1203. When the pressure of the exhaust gas post-buffer tank is high or the pressure of the exhaust gas pre-buffer tank 10 is too low, the reflux regulating valve 1203 is opened and the exhaust gas returns to the exhaust gas pre-buffer tank 10 through the reflux pipe 1202.

[0093] When the reflux regulating valve 1203 is not adjusted in time or the pressure of the exhaust gas pre-buffer tank 10 is too high, the washing valve 1205 can also be opened to send the exhaust gas through the washing pipe 1204 and the washing input pipe 505 to the power wave mixer 6 for neutralization treatment.

[0094] The exhaust gas, after being pressurized in the exhaust gas buffer tank 12, is transported to downstream process units (not shown in this application) through the nitrogen output pipeline 1206 to replace fresh nitrogen as the pressurization, stabilization and safe emission gas of the production system.

[0095] The chlorosilane condensate in the pre-buffer tank 10 is collected in the condensate tank 3 through the pre-liquid output pipe 1001. The chlorosilane condensate in the post-buffer tank 12 is collected in the condensate tank 3 through the post-liquid output pipe 1201 and the pre-liquid output pipe 1001. The condensate in the condensate tank 3 is sent to the recovery pump 4 through the recovery pipe 301, and then transported to the chlorosilane recovery device (not shown in this application) through the external transmission pipe 401.

[0096] This application primarily reduces nitrogen usage during polysilicon production, lowers operating costs, and enables secondary recycling of exhaust gas, reducing exhaust gas treatment load, minimizing hydrolysis waste gas generation and environmental hazards, and saving production costs.

[0097] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0098] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0099] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0100] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0101] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A polycrystalline silicon industrial waste gas recovery and utilization system, characterized in that, It includes an exhaust gas buffer tank (1), a condenser, an exhaust gas pre-buffer tank (10), a compressor (11), and an exhaust gas post-buffer tank (12); The exhaust gas buffer tank (1) is connected to an exhaust gas venting main pipe (101) for inputting exhaust gas; The input end of the condenser is connected to the exhaust gas buffer tank (1) through the exhaust pipe (102) for condensing the exhaust gas input to the exhaust gas buffer tank (1) and transporting the remaining non-condensable gas to the exhaust gas front buffer tank (10) through the non-condensable gas pipe (501). The compressor (11) is connected between the exhaust gas front buffer tank (10) and the exhaust gas rear buffer tank (12) and is used to compress the gas in the exhaust gas front buffer tank (10) into the exhaust gas rear buffer tank (12). The exhaust gas buffer tank (12) is also connected to a nitrogen output pipe (1206) for outputting nitrogen.

2. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 1, characterized in that, A valve is installed on the nitrogen output pipeline (1206).

3. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 1, characterized in that, The system also includes a condensate tank (3); The bottom of both the exhaust gas pre-buffer tank (10) and the exhaust gas post-buffer tank (12) is provided with a liquid output end; the liquid output ends of the exhaust gas pre-buffer tank (10) and the exhaust gas post-buffer tank (12) are connected to the condensate tank (3) through a liquid output pipe.

4. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 3, characterized in that, The exhaust gas pre-buffer tank (10) is connected to the condensate tank (3) via the pre-liquid output pipe (1001); the exhaust gas post-buffer tank (12) is connected to the pre-liquid output pipe (1001) via the post-liquid output pipe (1201); Valves are installed on both the front liquid output pipe (1001) and the rear liquid output pipe (1201).

5. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 4, characterized in that, The bottom of the condensate tank (3) is connected to a recovery pump (4), which is used to transport the liquid in the condensate tank (3) to the outside to recover silicon chloride.

6. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 1, characterized in that, The exhaust gas front buffer tank (10) and the exhaust gas rear buffer tank (12) are connected by a return pipe (1202), and a return regulating valve (1203) is provided on the return pipe (1202).

7. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 6, characterized in that, The system also includes an exhaust gas scrubbing subsystem; The exhaust gas scrubbing subsystem is connected to the non-condensable gas pipeline (501) via a check valve (504), thereby receiving gas from the non-condensable gas pipeline (501) in one direction for exhaust gas scrubbing.

8. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 7, characterized in that, The exhaust gas buffer tank (12) is also connected to the exhaust gas washing subsystem via a washing pipe (1204); a washing valve (1205) is provided on the washing pipe (1204).

9. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 8, characterized in that, The system also includes a gas detector (AI001) installed on the exhaust gas after buffer tank (12), used to analyze the gas oxygen content and / or dew point of the gas in the exhaust gas after buffer tank (12) and output the results for display. When the oxygen content and / or dew point of the gas in the exhaust gas buffer tank (12) exceeds the preset value, the gas detector (AI001) will sound an alarm and control the washing valve (1205) to open.

10. The polycrystalline silicon industrial waste gas recovery and utilization system according to claim 8, characterized in that, The system also includes a pressure detector (PI001) installed on the exhaust gas after buffer tank (12) for collecting and displaying the gas pressure in the exhaust gas after buffer tank (12); When the gas pressure in the buffer tank (12) after the exhaust gas is collected exceeds the preset value, the pressure detector (PI001) will sound an alarm and control the washing valve (1205) or the reflux regulating valve (1203) to open.

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