Polycrystalline silicon production waste gas adsorption tower on-line detection device

Abstract

The utility model discloses an on-line detection device for a polycrystalline silicon production waste gas adsorption tower, relates to the technical field of polycrystalline silicon production, and mainly aims to judge gas components adsorbed by the adsorption tower on line, reduce alkali consumption and reduce chlorosilane loss. The main technical scheme of the utility model is as follows: the on-line detection device for the polycrystalline silicon production waste gas adsorption tower comprises an adsorption tower and a detection part, an outlet in the upper end of the adsorption tower is connected to the alkali liquor leaching unit and the deep cooling unit respectively; the detection part comprises a regulating valve, a filter, an electric heater, a temperature sensor and a gas chromatograph which are sequentially connected, an inlet of the regulating valve is connected to an outlet in the upper end of the adsorption tower, and an outlet of the gas chromatograph is connected to the alkali liquor leaching unit and the deep cooling unit.

Description

TECHNICAL FIELD

[0001] The utility model relates to polycrystal silicon production technical field especially relates to a polycrystal silicon production waste gas adsorption tower on -line detection device. BACKGROUND

[0002] Polycrystal silicon is the basic raw material of the current photovoltaic industry, and the main method for producing polycrystal silicon is the modified Siemens method. The main processes of the modified Siemens method include cold hydrogenation synthesis of trichlorosilane (TCS), rectification and purification of TCS, reduction reaction of high-purity TCS, and tail gas recovery, etc. In the production process, these sections will produce waste gas composed of dichlorosilane (DCS), silicon tetrachloride (STC), hydrogen (H2), hydrogen chloride (HCl) and TCS, etc. These waste gases are mostly toxic, harmful, flammable and explosive substances, and need to be treated further to reach the emission standard before being discharged. The main method currently used is dry recovery, and the main process of dry recovery is as shown in Figure 1 The core of dry recovery is the adsorption tower, and the larger the capacity of the adsorption tower, the less the chlorosilane content in the waste gas, and the less the loss of the production system, so that the modified Siemens method can realize true closed cycle. Due to the influence of random pressure relief of the production system, the adsorption capacity of the adsorption tower under different working conditions changes. If the waste gas amount is large on that day, the adsorption capacity of the adsorption tower will be saturated, and chlorosilane will directly go to the caustic lye washing from the top of the adsorption tower, causing the increase of chlorosilane loss and the increase of caustic lye consumption. Taking a 60,000-ton-per-year polycrystal silicon project as an example, the average daily caustic lye consumption is about 30t, which is equivalent to the loss of 30t / day of chlorosilane, and the annual loss is close to 50 million yuan.

[0003] To evaluate the adsorption capacity of the adsorption tower, on the one hand, the size of the treated waste gas amount needs to be considered, and the larger the treated waste gas amount, the stronger the adsorption capacity; on the other hand, when the waste gas amount is certain, the lower the chlorosilane and HCl content in the adsorption tower, the stronger the adsorption capacity. At present, the chlorosilane and HCl content in the adsorption tower can only be deduced by analyzing the caustic lye consumption of the rear section, which has strong hysteresis and cannot adjust the parameters of the adsorption tower in time to ensure the stability of production; another method is to use offline detection to take the gas sample from the top of the adsorption tower to the laboratory for offline analysis. However, the representative sample cannot be taken by offline detection, and the deviation between the detection result and the actual value is large. Therefore, a set of online detection method and equipment are needed to determine the components in the adsorption tower to evaluate the adsorption capacity of the adsorption tower.

[0004] Current methods for treating polysilicon waste gas primarily employ dry recovery, which generally includes a waste gas buffer system, a waste gas pressurization system, a waste gas condensation system, and an adsorption system. While the technologies for waste gas buffering, pressurization, and condensation systems are relatively mature, the detection of gas components at the adsorption tower outlet in the adsorption system remains a significant challenge for dry recovery. As mentioned earlier, the waste gas treatment volume fluctuates due to unstable emissions from upstream processes (for example, with an annual polysilicon production capacity of 60,000 tons, the waste gas volume is approximately 3000 Nm³). 3 / h-6000Nm 3 Fluctuations in waste gas volume ( / h) can lead to unstable operation of the adsorption tower. When the waste gas volume suddenly exceeds the maximum adsorption capacity of the adsorption tower for a certain period, it can cause the adsorption tower to fail and lose its adsorption capacity. Currently, samples are taken from the top of the adsorption tower using gas cylinders and then analyzed offline. However, the test results show almost no acidic gases, which is seriously inconsistent with actual production operation. Therefore, the only way to reduce the acidic substance content at the adsorption tower outlet is to adjust the alkaline consumption during the downstream alkaline rinsing process. However, this method is too slow and not conducive to timely production adjustments.

[0005] Therefore, the existing technology has the following drawbacks:

[0006] 1. Offline testing requires manual sampling, which necessitates opening the drain at the adsorption tower outlet, posing a risk of injury to sampling personnel.

[0007] 2. Currently, offline detection methods cannot obtain representative samples, resulting in significant discrepancies between the detection results and actual operation.

[0008] 3. The current operating mode has a strong lag, resulting in a large consumption of alkali solution and losses of chlorosilane. Utility Model Content

[0009] In view of this, the present invention provides an online detection device for polycrystalline silicon production waste gas adsorption tower, the main purpose of which is to determine the composition of the gas after adsorption in the adsorption tower online, thereby reducing alkali consumption and chlorosilane loss.

[0010] To achieve the above objectives, this utility model mainly provides the following technical solutions:

[0011] This utility model provides an online detection device for polysilicon production waste gas adsorption tower, the device comprising: an adsorption tower and a detection unit;

[0012] The upper outlet of the adsorption tower is connected to the alkaline rinsing unit and the cryogenic unit, respectively.

[0013] The detection part comprises a regulating valve, a filter, an electric heater, a temperature sensor and a gas chromatograph connected in sequence, the inlet of the regulating valve is connected to the upper end outlet of the adsorption tower, and the outlet of the gas chromatograph is connected to the alkali liquid elution unit and the cryogenic unit respectively.

[0014] The purposes and technical problems of the utility model can also be further realized by the following technical measures.

[0015] Optionally, the upper end outlet of the adsorption tower is connected to the alkali liquid elution unit through a first pipeline and to the cryogenic unit through a second pipeline, the outlet of the gas chromatograph is connected to the alkali liquid elution unit through a third pipeline and to the cryogenic unit through a fourth pipeline, the first pipeline is provided with a first control valve, the second pipeline is provided with a second control valve, the third pipeline is provided with a third control valve, and the fourth pipeline is provided with a fourth control valve.

[0016] Optionally, the adsorption tower comprises a first adsorption tower, a second adsorption tower and a third adsorption tower connected in parallel, the upper end outlet of the first adsorption tower is connected to the inlet of the regulating valve through a first branch pipe, the upper end outlet of the second adsorption tower is connected to the inlet of the regulating valve through a second branch pipe, the upper end outlet of the third adsorption tower is connected to the inlet of the regulating valve through a third branch pipe, the first branch pipe is provided with a fifth control valve, the second branch pipe is provided with a sixth control valve, and the third branch pipe is provided with a seventh control valve.

[0017] Optionally, the first branch pipe, the second branch pipe and the third branch pipe are respectively provided with check valves.

[0018] Optionally, the upper end outlet of the first adsorption tower, the upper end outlet of the second adsorption tower and the upper end outlet of the third adsorption tower are respectively connected to nitrogen purge pipes.

[0019] Optionally, the alkali liquid elution unit comprises a elution tower, an alkali liquid tank, a water seal tank, a buffer tank and a plate and frame filter press, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph are respectively connected to the waste gas inlets of the elution tower, the alkali liquid tank is connected to the inlet of an alkali liquid pump, the outlet of the alkali liquid pump is connected to the spraying pipe of the elution tower, the upper end exhaust pipe of the spraying tower is connected to the water seal tank, the lower end liquid discharge pipe of the spraying tower is connected to the inlet of the buffer tank, and the outlet of the buffer tank is connected to the plate and frame filter press.

[0020] Optionally, the deep cooling unit comprises a first heat exchanger, a second heat exchanger and a third heat exchanger connected in sequence in a tube side, the outlet of the upper end of the adsorption tower and the outlet of the gas chromatograph are connected to the inlet of the tube side of the first heat exchanger respectively, the outlet of the tube side of the third heat exchanger is connected to a gas-liquid separation tank, the lower end liquid discharge pipe of the gas-liquid separation tank is connected to a rectification unit, the upper end gas discharge pipe of the gas-liquid separation tank is connected to the inlet of the shell side of the second heat exchanger, and the outlet of the shell side of the second heat exchanger is connected to the inlet of the lower end of the adsorption tower.

[0021] By the above technical scheme, the utility model has at least the following advantages:

[0022] In use of the device, the upper end outlet valve of the adsorption tower in the adsorption state is opened, and the waste gas after the adsorption of the adsorption tower is divided into two parts, wherein one part of the waste gas flows through the adjusting valve, the filter, the electric heater, the temperature sensor and the gas chromatograph in sequence, in the above process, the opening of the adjusting valve is adjusted by the controller, the gas amount entering the gas chromatograph can be effectively controlled, the filter effectively filters the small amount of impurities at the outlet of the adsorption tower, prevents the gas chromatographic column from being blocked, the electric heater and the temperature sensor are interlocked and controlled by the controller, the sample injection temperature of the gas chromatographic column tends to the design temperature of the gas chromatograph, and the component concentration of the waste gas after the adsorption of the adsorption tower is measured by the gas chromatograph.

[0023] When the concentration of chlorosilane in the waste gas component is less than 0.1%, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph are communicated with the alkali leaching unit respectively, the waste gas after the adsorption enters the alkali leaching unit, the acidic gas component in the waste gas is removed, and then the waste gas is emptied.

[0024] When the concentration of chlorosilane in the waste gas component is greater than 0.1%, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph are communicated with the deep cooling unit respectively, the waste gas after the adsorption enters the deep cooling unit, and the chlorosilane in the waste gas is continuously cooled and recovered, so that the loss of chlorosilane in the polysilicon process system is reduced, and the alkali consumption is also reduced. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a polysilicon production waste gas treatment process flow chart;

[0026] Figure 2 It is a structure schematic view of a polysilicon production waste gas adsorption tower on-line detection device provided by the utility model embodiment;

[0027] Figure 3 It is a structure schematic view of an alkali leaching unit;

[0028] Figure 4 It is a structure schematic view of a deep cooling unit;

[0029] Figure 5 It is a structure schematic view of a gas chromatograph.

[0030] The reference numerals in the accompanying drawings include: 1. Alkaline elution unit; 2. Cryogenic unit; 3. Control valve; 4. Filter; 5. Electric heater; 6. Temperature sensor; 7. Gas chromatograph; 7. Flow limiting orifice plate; 701. Pressure control valve; 702. Pressure transmitter; 703. Microfilter; 704. Electromagnetic flowmeter; 705. Column pre-column control valve; 706. Quantitative loop; 707. Gas chromatographic column; 708. Detector; 709. First pipe; 8. Second pipe; 9. Third pipe; 10. Fourth pipe; 11. First control valve; 12. Second control valve; 13. Second control valve; 14. Third control valve; 15. Fourth control valve; 16. Third control valve; 17. Fourth control valve; 18. Third control valve; 19. Third control valve; 10. Fourth control valve; 11. First control valve; 12. Second control valve; 13. Third control valve; 14. Third control valve; 15. Fourth control valve; 16. Third control valve; 17. Third control valve; 18. Third control valve; 19. Fourth control valve; 10. Third control valve; 11. Third control valve; 12. Third control valve; 13. Third control valve; 14. Third control valve; 15. Fourth control valve; 16. Third control valve; 17. Third control valve; 18. Third control valve; 19. Third control valve; 10. Third control valve; 11. Fourth control valve; 12. Third control valve; 13. Third control valve; 14. Third control valve; 15. Third control valve; 16. Third control valve; 17. Third control valve; 18. Third control valve; 19. Third control valve; 10. Third control valve; 19. Fourth Control valve 13, third control valve 14, fourth control valve 15, first adsorption tower 16, second adsorption tower 17, third adsorption tower 18, first branch pipe 19, second branch pipe 20, third branch pipe 21, fifth control valve 22, sixth control valve 23, seventh control valve 24, check valve 25, nitrogen purging pipe 26, scrubbing tower 27, alkali tank 28, water seal tank 29, buffer tank 30, plate and frame filter press 31, first heat exchanger 32, second heat exchanger 33, third heat exchanger 34, gas-liquid separator 35. Detailed Implementation

[0031] To further illustrate the technical means and effects adopted by this utility model to achieve its intended purpose, the specific implementation methods, structures, features, and effects according to this utility model application are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0033] like Figure 2 As shown, an embodiment of this utility model provides an online detection device for polycrystalline silicon production waste gas adsorption tower, which includes: an adsorption tower and a detection unit;

[0034] The upper outlet of the adsorption tower is connected to the alkaline rinsing unit 1 and the cryogenic unit 2, respectively.

[0035] The detection unit includes a regulating valve 3, a filter 4, an electric heater 5, a temperature sensor 6, and a gas chromatograph 7 connected in sequence. The inlet of the regulating valve 3 is connected to the upper outlet of the adsorption tower, and the outlet of the gas chromatograph 7 is connected to the alkaline elution unit 1 and the cryogenic unit 2, respectively.

[0036] The working process of the online monitoring device for the polysilicon production waste gas adsorption tower is as follows:

[0037] When using this device, the upper outlet valve of the adsorption tower in the adsorption state is opened. The waste gas after adsorption in the adsorption tower is divided into two parts. One part of the waste gas flows sequentially through the regulating valve 3, filter 4, electric heater 5, temperature sensor 6, and gas chromatograph 7. During the above process, the opening of the regulating valve 3 can be adjusted by the controller to effectively control the amount of gas entering the gas chromatograph 7. The filter 4 effectively filters out a small amount of impurities at the outlet of the adsorption tower to prevent blockage of the gas chromatograph column. The electric heater 5, temperature sensor 6, and gas chromatograph 7 are interlocked by the controller to control the injection temperature of the gas chromatograph column to approach the design temperature of the gas chromatograph column. The concentration of the waste gas components after adsorption in the adsorption tower is measured by the gas chromatograph 7.

[0038] When the concentration of chlorosilane in the waste gas components is less than 0.1%, the outlet at the top of the adsorption tower and the outlet of the gas chromatograph 7 are connected to the alkaline rinsing unit 1, respectively. After adsorption, the waste gas enters the alkaline rinsing unit 1 to remove the acidic gas components, and then is discharged into the air.

[0039] When the concentration of chlorosilane in the waste gas component is greater than 0.1%, the outlet at the top of the adsorption tower and the outlet of the gas chromatograph 7 are connected to the cryogenic unit 2 respectively. After adsorption, the waste gas enters the cryogenic unit 2 to continue cooling and recovering the chlorosilane in the waste gas, thereby reducing the loss of chlorosilane in the polycrystalline silicon process system and also reducing the alkali consumption.

[0040] like Figure 5 As shown, specifically, the gas chromatograph 7 has a dual-channel inlet channel, including a flow-limiting orifice plate 701, a pressure control valve 702, a pressure transmitter 703, a microfilter 704, an electromagnetic flowmeter 705, a column pre-control valve 706, a metering loop 707, a gas chromatographic column 708, and a detector 709. The detector 709 is connected to both the alkaline elution unit 1 and the cryogenic unit 2. The chromatographic column is an inert metal capillary column made of stainless steel, which has good corrosion resistance. The detector 709 is a flame photometric detector (FPD), and the detection data is automatically acquired after processing by relevant software.

[0041] Specifically, this device enables real-time and accurate monitoring of the concentration of gas components at the top outlet of the waste gas adsorption tower.

[0042] like Figure 2 As shown, in a specific embodiment, the upper outlet of the adsorption tower is connected to the alkaline elution unit 1 via a first pipe 8 and to the cryogenic unit 2 via a second pipe 9. The outlet of the gas chromatograph 7 is connected to the alkaline elution unit 1 via a third pipe 10 and to the cryogenic unit 2 via a fourth pipe 11. A first control valve 12 is installed on the first pipe 8, a second control valve 13 is installed on the second pipe 9, a third control valve 14 is installed on the third pipe 10, and a fourth control valve 15 is installed on the fourth pipe 11.

[0043] In this embodiment, specifically, when the gas chromatograph 7 detects that the concentration of chlorosilane in the waste gas component is greater than 0.1%, the second control valve 13 and the fourth control valve 15 are opened; when the gas chromatograph 7 detects that the concentration of chlorosilane in the waste gas component is less than 0.1%, the first control valve 12 and the third control valve 14 are opened.

[0044] like Figure 2 As shown, in a specific embodiment, the adsorption tower includes a first adsorption tower 16, a second adsorption tower 17, and a third adsorption tower 18 connected in parallel. The upper outlet of the first adsorption tower 16 is connected to the inlet of the regulating valve 3 through a first branch pipe 19. The upper outlet of the second adsorption tower 17 is connected to the inlet of the regulating valve 3 through a second branch pipe 20. The upper outlet of the third adsorption tower 18 is connected to the inlet of the regulating valve 3 through a third branch pipe 21. A fifth control valve 22 is installed on the first branch pipe 19, a sixth control valve 23 is installed on the second branch pipe 20, and a seventh control valve 24 is installed on the third branch pipe 21.

[0045] In this embodiment, specifically, assuming that at a certain moment, the first adsorption tower 16 adsorbs, the second adsorption tower 17 regenerates, and the third adsorption tower 18 cools, then the fifth control valve is opened, and the sixth control valve 23 and the seventh control valve 24 are closed. The activated carbon in the first adsorption tower 16 adsorbs the acidic substances in the waste gas in a low temperature and high pressure environment. The remaining nitrogen, hydrogen and a small amount of chlorosilane and hydrogen chloride are discharged from the top of the adsorption tower to the alkaline rinsing unit 1 or the cryogenic unit 2.

[0046] The first adsorption tower 16, the second adsorption tower 17, and the third adsorption tower 18 sequentially circulate online adsorption, while the fifth control valve 22, the sixth control valve 23, and the seventh control valve 24 sequentially open in a cyclical manner. This allows for the monitoring of the online adsorption effect of chlorosilanes in the adsorption towers. The standard is whether the chlorosilane concentration is greater than 0.1%, thereby determining whether the waste gas should be cryogenically recovered again or discharged after alkaline washing.

[0047] like Figure 2 As shown, in a specific embodiment, the first branch pipe 19, the second branch pipe 20 and the third branch pipe 21 are respectively equipped with check valves 25.

[0048] In this embodiment, specifically, due to the setting of the check valve 25, the waste gas to be detected is prevented from flowing back to the adsorption tower along the first branch pipe 19, the second branch pipe 20 and the third branch pipe 21, thus ensuring the stability of the waste gas flow rate entering the gas chromatograph 7.

[0049] like Figure 2As shown in the specific embodiment, the upper end outlet of the first adsorption tower 16, the upper end outlet of the second adsorption tower 17 and the upper end outlet of the third adsorption tower 18 are respectively connected to the nitrogen purge pipe 26.

[0050] In the present embodiment, specifically, when switching the online adsorption tower (the first adsorption tower 16 switches to the second adsorption tower 17), before switching, the valve of the nitrogen purge pipe 26 of the upper end outlet of the first adsorption tower 16 is opened, nitrogen is used to purge the first branch pipe 19 and the subsequent pipeline, the residual waste gas from the first adsorption tower 16 in the subsequent pipeline is removed, and then the second adsorption tower 17 is switched, so as to avoid the influence of the residual waste gas on the detection accuracy of the gas chromatograph 7 on the concentration of the waste gas components after the adsorption of the second adsorption tower 17.

[0051] As shown in the specific embodiment, the upper end outlet of the first adsorption tower 16, the upper end outlet of the second adsorption tower 17 and the upper end outlet of the third adsorption tower 18 are respectively connected to the nitrogen purge pipe 26. Figure 3 As shown in the specific embodiment, the alkali elution unit 1 includes an elution tower 27, an alkali tank 28, a water seal tank 29, a buffer tank 30 and a plate and frame filter press 31, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph 7 are respectively connected to the waste gas inlet of the elution tower 27, the alkali tank 28 is connected to the inlet of an alkali pump, the outlet of the alkali pump is connected to the spraying pipe of the elution tower 27, the upper end exhaust pipe of the spraying tower is connected to the water seal tank 29, the lower end liquid discharge pipe of the spraying tower is connected to the inlet of the buffer tank 30, and the outlet of the buffer tank 30 is connected to the plate and frame filter press 31.

[0052] In the present embodiment, specifically, when the gas chromatograph 7 detects that the concentration of chlorosilane in the waste gas is less than 0.1%, the waste gas discharged from the online adsorption tower and the gas chromatograph 7 enters the elution tower 27 and is subjected to alkali spraying to remove the acidic components in the waste gas, the neutralized waste gas enters the water seal tank 29 and is then emptied, and meanwhile, the solution after elution and cooling enters the buffer tank 30, the solution contains solid impurities, the solution passes through the plate and frame filter press 31 to remove the solid impurities, and the remaining clear liquid is discharged to avoid environmental pollution.

[0053] As shown in the specific embodiment, the alkali elution unit 1 includes an elution tower 27, an alkali tank 28, a water seal tank 29, a buffer tank 30 and a plate and frame filter press 31, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph 7 are respectively connected to the waste gas inlet of the elution tower 27, the alkali tank 28 is connected to the inlet of an alkali pump, the outlet of the alkali pump is connected to the spraying pipe of the elution tower 27, the upper end exhaust pipe of the spraying tower is connected to the water seal tank 29, the lower end liquid discharge pipe of the spraying tower is connected to the inlet of the buffer tank 30, and the outlet of the buffer tank 30 is connected to the plate and frame filter press 31. Figure 4 As shown in the specific embodiment, the alkali elution unit 1 includes an elution tower 27, an alkali tank 28, a water seal tank 29, a buffer tank 30 and a plate and frame filter press 31, the upper end outlet of the adsorption tower and the outlet of the gas chromatograph 7 are respectively connected to the waste gas inlet of the elution tower 27, the alkali tank 28 is connected to the inlet of an alkali pump, the outlet of the alkali pump is connected to the spraying pipe of the elution tower 27, the upper end exhaust pipe of the spraying tower is connected to the water seal tank 29, the lower end liquid discharge pipe of the spraying tower is connected to the inlet of the buffer tank 30, and the outlet of the buffer tank 30 is connected to the plate and frame filter press 31.

[0054] In the embodiment, specifically, the shell side of the first heat exchanger 32 uses 7℃ water as the cooling medium, and the shell side of the third heat exchanger 34 uses freon as the cooling medium; when the gas chromatograph 7 detects that the concentration of chlorosilane in the exhaust gas is greater than 0.1%, the exhaust gas discharged from the online adsorption tower and the gas chromatograph 7 enters the first heat exchanger 32, the second heat exchanger 33 and the third heat exchanger 34 in sequence, and finally realizes gas-liquid separation in the gas-liquid separation tank 35, the gas in which enters the adsorption tower again for impurity removal, and the liquid phase components in which enter the rectification unit;

[0055] Through the above process, the chlorosilane in the exhaust gas components is condensed and liquefied to the maximum extent for rectification, and the uncondensed gas in the exhaust gas enters the adsorption tower again, so that only the gas after being washed by the washing tower 27 can be exhausted in the whole system, the above process maximizes the guarantee of the recovery rate of chlorosilane, and reduces the amount of alkali solution used.

[0056] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An online detection device for a polycrystalline silicon production waste gas adsorption tower, characterized in that, include: An adsorption tower, the upper outlet of which is connected to an alkaline rinsing unit and a cryogenic unit respectively. The detection unit includes a regulating valve, a filter, an electric heater, a temperature sensor, and a gas chromatograph connected in sequence. The inlet of the regulating valve is connected to the upper outlet of the adsorption tower, and the outlet of the gas chromatograph is connected to the alkaline elution unit and the cryogenic unit, respectively.

2. The online detection device for the polycrystalline silicon production waste gas adsorption tower according to claim 1, characterized in that, The upper outlet of the adsorption tower is connected to the alkaline elution unit via a first pipe and to the cryogenic unit via a second pipe. The outlet of the gas chromatograph is connected to the alkaline elution unit via a third pipe and to the cryogenic unit via a fourth pipe. A first control valve is installed on the first pipe, a second control valve is installed on the second pipe, a third control valve is installed on the third pipe, and a fourth control valve is installed on the fourth pipe.

3. The online detection device for the polycrystalline silicon production waste gas adsorption tower according to claim 2, characterized in that, The adsorption tower includes a first adsorption tower, a second adsorption tower, and a third adsorption tower connected in parallel. The upper outlet of the first adsorption tower is connected to the inlet of the regulating valve through a first branch pipe. The upper outlet of the second adsorption tower is connected to the inlet of the regulating valve through a second branch pipe. The upper outlet of the third adsorption tower is connected to the inlet of the regulating valve through a third branch pipe. A fifth control valve is installed on the first branch pipe, a sixth control valve is installed on the second branch pipe, and a seventh control valve is installed on the third branch pipe.

4. The online detection device for the polycrystalline silicon production waste gas adsorption tower according to claim 3, characterized in that, The first branch pipe, the second branch pipe and the third branch pipe are each equipped with a check valve.

5. The online detection device for the polycrystalline silicon production waste gas adsorption tower according to claim 3, characterized in that, The upper outlets of the first adsorption tower, the second adsorption tower, and the third adsorption tower are respectively connected to nitrogen purging pipes.

6. The online detection device for polycrystalline silicon production waste gas adsorption tower according to any one of claims 1 to 5, characterized in that, The alkaline rinsing unit includes a rinsing tower, an alkaline tank, a water seal tank, a buffer tank, and a plate and frame filter press. The upper outlet of the adsorption tower and the outlet of the gas chromatograph are respectively connected to the exhaust gas inlet of the rinsing tower. The alkaline tank is connected to the inlet of the alkaline pump. The outlet of the alkaline pump is connected to the spray pipe of the rinsing tower. The upper exhaust pipe of the spray tower is connected to the water seal tank. The lower drain pipe of the spray tower is connected to the inlet of the buffer tank. The outlet of the buffer tank is connected to the plate and frame filter press.

7. The online detection device for polycrystalline silicon production waste gas adsorption tower according to any one of claims 1 to 5, characterized in that, The cryogenic unit includes a first heat exchanger, a second heat exchanger, and a third heat exchanger connected in sequence by tubes. The upper outlet of the adsorption tower and the outlet of the gas chromatograph are respectively connected to the tube inlet of the first heat exchanger. The tube outlet of the third heat exchanger is connected to a gas-liquid separator. The lower drain pipe of the gas-liquid separator is connected to a distillation unit. The upper exhaust pipe of the gas-liquid separator is connected to the shell inlet of the second heat exchanger. The shell outlet of the second heat exchanger is connected to the lower inlet of the adsorption tower.

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