A system for recovering and purifying argon gas from monocrystalline silicon process waste gas

Abstract

This invention discloses an argon recovery and purification system for waste gas from monocrystalline silicon production processes, aiming to solve the technical problems of high argon extraction costs and argon resource waste during production. The system includes a multi-stage purification unit, a waste gas collection and transportation unit, a compression and pretreatment unit, an adsorption purification unit, a cryogenic distillation unit, and a refrigerant circulation and product output unit, all connected sequentially via pipelines. This invention employs a three-stage purification process—cyclone separation, bag filtration, and oil mist filtration—to remove particulate and oil mist impurities; a combined process of carbon monoxide adsorption, catalytic deoxygenation, and deep drying to remove gaseous impurities; and cryogenic distillation technology to achieve argon-nitrogen separation. A liquid argon storage tank with a diversion design simultaneously provides refrigerant to the distillation column and serves as a product output outlet. Ultimately, the purified high-purity argon is recycled back to the silicon crystal furnace, forming a closed-loop production system. This system boasts significant advantages, including high recovery rate, high product purity, low operating costs, and high resource utilization.

Description

Technical Field

[0001] This utility model belongs to the field of argon recovery and purification technology, specifically relating to an argon recovery and purification system for waste gas from monocrystalline silicon processes. Background Technology

[0002] Argon, as an important inert protective gas, is widely used in the single-crystal silicon pulling process to prevent oxidation of silicon materials at high temperatures. However, argon is present in extremely low concentrations in the air, accounting for only about 0.93%. Extraction using traditional air separation methods is not only technically challenging but also prohibitively expensive, making it a scarce and valuable resource. Currently, China has the world's largest number of single-crystal furnaces, and this number is rapidly increasing. Each furnace consumes a huge amount of argon annually, generating substantial amounts of argon-rich process waste gas. Directly discharging this waste gas not only results in a severe waste of argon resources but also increases production costs and environmental burden. Therefore, developing a technology and device that can efficiently and economically recover and purify argon from single-crystal silicon process waste gas, achieving the recycling of this scarce resource, has become a critical technical problem urgently needing to be solved in this field. Utility Model Content

[0003] This invention aims to provide a system for recovering and purifying argon gas from monocrystalline silicon process waste gas, solving the technical problems of high argon extraction costs, huge argon consumption during monocrystalline silicon production, and serious resource waste caused by direct emission of process waste gas in the existing technology.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A system for recovering and purifying argon gas from monocrystalline silicon process waste gas includes: Silicon crystal furnace; The multi-stage purification unit includes a cyclone separator, a bag filter, and an oil mist filter connected in sequence by pipes. The exhaust gas outlet of the silicon crystal furnace is connected to the cyclone separator by a pipe, and a vacuum pump is installed on the pipe. The exhaust gas collection and conveying unit includes a duct fan and a dual-membrane gas holder connected in sequence by a pipeline, and the oil mist filter is connected to the duct fan. The compression and pretreatment unit includes an intake filter and a raw gas compressor connected in sequence by pipelines, and the intake filter is connected to a dual-membrane gas holder; The adsorption and purification unit includes a carbon monoxide removal adsorbent, a deoxygenation adsorbent, and a purifier connected in sequence by pipelines. The carbon monoxide removal adsorbent is connected to the raw material gas compressor. The deoxygenation adsorbent is also connected to an electrolytic water hydrogen production device via a pipeline. The low-temperature distillation unit includes a distillation column and a heat exchanger connected in sequence by pipes, and the heat exchanger is connected to a purifier by pipes; the top of the distillation column is connected to a waste gas discharge pipe; The product output and recycling unit includes a liquid argon storage tank, a vaporizer, and an argon compressor. The outlet of the liquid argon storage tank is connected to the distillation column and the vaporizer via pipelines. The gas phase outlet of the vaporizer is connected to the recycling inlet of the silicon crystal furnace via a recycling pipeline. The inlet of the argon compressor is connected to the heat exchanger, and its outlet is connected to the recycling pipeline from the vaporizer to the silicon crystal furnace.

[0005] Furthermore, the aforementioned argon recovery and purification system for monocrystalline silicon process waste gas also includes a heater, which is installed on the connecting pipe between the raw material gas compressor and the carbon monoxide adsorber.

[0006] Furthermore, the heat exchanger is connected to the distillation column via two heat exchange pipes to form a heat exchange loop.

[0007] Compared with existing technologies, the beneficial effects of this invention are as follows: First, this invention uses a three-stage series purification process of cyclone separation, bag filtration, and oil mist filtration to efficiently remove particulate matter and oily impurities from the waste gas, ensuring the stable operation of subsequent equipment. Then, a deep purification process combining catalytic deoxygenation and adsorption is employed to thoroughly remove gaseous impurities such as oxygen, carbon monoxide, and moisture. Finally, low-temperature distillation technology is used to achieve efficient separation of argon and nitrogen. Through a unique refrigerant and product synergistic circulation design, the recovered and purified high-purity argon is directly reused in the silicon crystal furnace, forming a complete closed-loop resource utilization. This not only increases the argon recovery and extraction rate to over 95% and the product purity to a stable 99.999%, but also significantly reduces production costs and dependence on expensive external argon resources, while simultaneously improving the resource utilization efficiency and environmental friendliness of monocrystalline silicon production. Attached Figure Description

[0008] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flow chart of the argon recovery process of this utility model. Detailed Implementation

[0009] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0010] The present invention will be further described in detail below with reference to the embodiments.

[0011] like Figure 1 As shown, this utility model discloses an argon recovery and purification system for monocrystalline silicon process waste gas, aiming to solve the problems of high argon extraction costs, huge argon consumption during monocrystalline silicon production, and resource waste caused by direct emission of waste gas in existing technologies. This utility model achieves efficient recovery and high-purity purification of argon from monocrystalline silicon process waste gas by constructing a complete waste gas purification system and argon purification system.

[0012] The aforementioned argon recovery and purification system for monocrystalline silicon process waste gas mainly includes a multi-stage purification unit, a waste gas collection and transportation unit, a compression and pretreatment unit, an adsorption purification unit, a low-temperature distillation unit, and a product output and reuse unit.

[0013] The operation of this system begins with the monocrystalline silicon crystal pulling process. During the monocrystalline silicon pulling process, argon gas is continuously and uniformly introduced into the furnace chamber of the silicon crystal furnace 1 as a protective gas. Simultaneously, vacuum pump 1 continuously evacuates gas from the furnace chamber to remove the waste gas generated during the process and maintains the vacuum level within the furnace chamber within the range of (2.7~5.3)×10³ Pa. The discharged waste gas is mainly composed of argon gas, but also contains impurities such as silicon dust, oxygen, nitrogen, carbon monoxide, carbon dioxide, and moisture.

[0014] First, the exhaust gas enters a multi-stage purification unit for physical purification. This unit is the front end of the exhaust gas purification system, employing a combination of multiple devices to remove solid and oily impurities in stages. Specifically, the exhaust gas first enters a cyclone separator 3 for the first stage of purification, using centrifugal force to separate and remove most of the larger silica powder particles. Then, the gas enters a bag filter 4 for the second stage of purification, where the fine fiber structure of the filter bags captures ultrafine dust particles. Finally, the airflow passes through an oil mist filter 5 for the third stage of purification, thoroughly removing oil mist and trace amounts of heavy metal vapor brought in by the vacuum pump 1. After three stages of purification, the solid and oily impurities in the exhaust gas have been effectively removed.

[0015] The purified waste gas is transported and treated by the waste gas collection and transportation unit. The duct fan 6 provides the power for the gas flow, sending the gas into the double-membrane gas holder 7. As a large, variable-capacity gas tank, the double-membrane gas holder 7 plays the role of collecting, buffering and storing gas, effectively balancing the instability of gas production at the front end and gas consumption at the back end, and ensuring the continuous and stable operation of the system.

[0016] The gas then enters the compression and pretreatment unit. First, it passes through the intake filter 8 for deep filtration, ensuring that any tiny particles that could damage the compressor are removed. Then, the feed gas compressor 9 compresses the gas, boosting it to the operating pressure required for subsequent adsorption and distillation processes.

[0017] The compressed gas then enters the adsorption purification unit, the first part of the argon purification system, primarily responsible for removing gaseous impurities. The gas first enters the carbon monoxide removal adsorber 11, where a specialized adsorbent selectively adsorbs and removes impurities such as carbon monoxide and carbon dioxide. Subsequently, the gas enters the oxygen removal adsorber 12. Simultaneously, hydrogen produced by the water electrolysis hydrogen production unit 13 is quantitatively added to the oxygen removal adsorber 12. Under the action of a catalyst within the oxygen removal adsorber 12, the hydrogen reacts catalytically with oxygen in the waste gas to generate water, effectively removing oxygen. Finally, the gas flows through the purifier 14, which is filled with a high-performance desiccant (such as a molecular sieve) for deep adsorption and removal of moisture generated during the above process, as well as residual trace amounts of moisture, ensuring the gas is extremely dry. In another preferred embodiment, the system also includes a heater 10, which is installed on the connecting pipe between the raw material gas compressor 9 and the carbon monoxide removal adsorber 11.

[0018] The deeply purified gas enters the cryogenic distillation unit, the core of the argon purification system, used to achieve the final separation of argon and nitrogen. The gas first enters heat exchanger 15, where it exchanges heat with the cryogenic product argon from distillation column 16, and is pre-cooled to a low temperature. It then enters distillation column 16, where the different boiling points of argon and nitrogen components are utilized for distillation separation at low temperature. Argon is liquefied and extracted from the bottom of the column, while non-condensable gases such as nitrogen, with even lower boiling points, accumulate at the top of distillation column 16 and are discharged as waste gas. This method has low energy consumption and produces products with extremely high purity and cleanliness.

[0019] Finally, the high-purity liquid argon product enters the product output and reuse unit. Specifically, the liquid argon storage tank 18 serves as the storage unit, and its outlet liquid argon is divided into two paths: the first path, where liquid argon is used as a refrigerant and transported through pipelines to the distillation column 16 to provide and replenish the required cooling for the distillation process; the second path, where liquid argon is used as a product and directly enters the vaporizer 19 through pipelines. In the vaporizer 19, the liquid argon is heated and vaporized into high-purity argon gas at room temperature. The high-purity argon gas at the outlet of the vaporizer 19 is directly transported back to the reuse inlet of the silicon crystal furnace 1 through the reuse pipeline, realizing the closed-loop recycling of argon gas. At the same time, to meet different output pressure requirements, a stream of product gas can be drawn from the heat exchanger 15, compressed to the required pressure by the argon compressor 17, and injected into the reuse pipeline for reuse together with the main gas flow or as high-pressure product gas output.

[0020] In another preferred embodiment, the heat exchanger 15 is connected to the distillation column 16 via two heat exchange pipes to form a heat exchange loop. This design constitutes an efficient internal reflux system, which draws the liquid at the bottom of the distillation column 16, heats it in the heat exchanger 15, and then partially vaporizes it before returning it to the column.

[0021] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0022] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for recovering and purifying argon gas from monocrystalline silicon process waste gas, characterized in that, include: Silicon crystal furnace; The multi-stage purification unit includes a cyclone separator, a bag filter, and an oil mist filter connected in sequence by pipes. The exhaust gas outlet of the silicon crystal furnace is connected to the cyclone separator by a pipe, and a vacuum pump is installed on the pipe. The exhaust gas collection and conveying unit includes a duct fan and a dual-membrane gas holder connected in sequence by a pipeline, and the oil mist filter is connected to the duct fan. The compression and pretreatment unit includes an intake filter and a raw gas compressor connected in sequence by pipelines, and the intake filter is connected to a dual-membrane gas holder; The adsorption and purification unit includes a carbon monoxide removal adsorbent, a deoxygenation adsorbent, and a purifier connected in sequence by pipelines. The carbon monoxide removal adsorbent is connected to the raw material gas compressor. The deoxygenation adsorbent is also connected to an electrolytic water hydrogen production device via a pipeline. The low-temperature distillation unit includes a distillation column and a heat exchanger connected in sequence by pipes, and the heat exchanger is connected to a purifier by pipes; the top of the distillation column is connected to a waste gas discharge pipe; The product output and recycling unit includes a liquid argon storage tank, a vaporizer, and an argon compressor. The outlet of the liquid argon storage tank is connected to the distillation column and the vaporizer via pipelines. The gas phase outlet of the vaporizer is connected to the recycling inlet of the silicon crystal furnace via a recycling pipeline. The inlet of the argon compressor is connected to the heat exchanger, and its outlet is connected to the recycling pipeline from the vaporizer to the silicon crystal furnace.

2. The system for recovering and purifying argon from monocrystalline silicon process exhaust gas according to claim 1, characterized in that, It also includes a heater, which is installed on the connecting pipe between the raw gas compressor and the carbon monoxide adsorber.

3. The system for recovering and purifying argon from monocrystalline silicon process exhaust gas according to claim 2, characterized in that, The heat exchanger is also connected to the distillation column via two heat exchange pipes to form a heat exchange loop.

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