Recovery method and recovery system for electronic grade dichlorosilane and helium

Abstract

The invention provides a recovery method and a recovery system for electronic grade dichlorosilane and helium, and belongs to the field of tail gas treatment.The recovery method comprises the steps that tail gas containing dichlorosilane and helium is filtered, and then solid particle impurities are removed; performing multistage gas-liquid separation and condensation on the tail gas from which the solid particle impurities are removed by utilizing the difference between boiling points of dichlorosilane and helium, so as to obtain liquid dichlorosilane and primarily separated gaseous helium; after the primarily separated gaseous helium is subjected to multi-stage adsorption, residual organic impurities and inorganic impurities in the helium are removed; and separating and purifying the impurity-removed helium through a multi-stage membrane, and removing residual impurities to obtain the high-purity helium. Harmless treatment of tail gas can be achieved, tail gas emission is reduced to the maximum extent, and energy consumption and environmental pollution are reduced; meanwhile, useful substances in the tail gas are recycled, and helium is purified to reach the purity standard which can be used for producing electronic-grade products again, so that the aim of recycling resources is fulfilled, the production cost is reduced, and the economic benefits of enterprises are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tail gas treatment, and particularly relates to a recovery method and a recovery system for electronic-grade dichlorodihydrogen silicon and helium. BACKGROUND

[0002] In the field of semiconductor manufacturing and the like, electronic-grade dichlorodihydrogen silicon is an important silicon source special gas in semiconductor manufacturing, and is often used in core processes such as thin film deposition and silicon epitaxial growth. In the production and filling process, helium is often used as a displacement gas or a protective gas to ensure the stability of the process and the quality of the product. However, the used helium is often directly discharged, causing waste of resources and increase in cost. Helium is a rare gas with limited reserves on earth and high acquisition cost. At the same time, directly discharging helium containing a small amount of impurities (such as trace amounts of dichlorodihydrogen silicon) also does not meet the environmental protection concept. Therefore, how to effectively recycle and utilize the displacement helium has become a problem to be solved in the field.

[0003] At present, although there are some helium recovery technologies, there are still problems of low recovery rate, difficult to guarantee purity, high recovery cost and the like for the recovery of helium containing electronic-grade dichlorodihydrogen silicon and the like. The traditional tail gas treatment process has many drawbacks: (1) Some traditional processes use a simple combustion method to treat tail gas, which can decompose part of the harmful substances, but produces a large amount of high-temperature waste gas, consumes a large amount of energy, and may produce new pollutants such as chlorine-containing organic compounds due to incomplete combustion, and cannot recover useful resources in the tail gas.

[0004] (2) Some wet treatment processes absorb tail gas by water or lye, but this easily leads to the generation of a large amount of wastewater containing high concentrations of silicides and chlorides, which is difficult and costly to treat, and may cause serious pollution to water bodies and soil if not properly treated.

[0005] (3) In addition, since electronic products have very high purity requirements, the traditional treatment process cannot effectively treat the tail gas while meeting the high-purity requirements of the recovered material, and cannot achieve efficient recycling of resources.

[0006] With the increasingly stringent environmental regulations and the pursuit of efficient use of resources in the electronics industry, it is urgent to develop an efficient, environmentally friendly and resource-recovering tail gas treatment process. SUMMARY

[0007] The embodiments of the present application provide a recovery method and a recovery system for electronic-grade dichlorodihydrogen silicon and helium, aiming to solve the problems of high energy consumption, low recovery rate and secondary pollution to the environment caused by the traditional treatment process.

[0008] In a first aspect, to achieve the above object, the present application adopts the technical solution of providing a recovery method for electronic-grade dichlorodihydrogen silicon and helium, the recovery method comprising: filtering the tail gas containing dichlorodihydrogen silicon and helium to remove solid particle impurities; using the difference in boiling points of dichlorodihydrogen silicon and helium, the tail gas after removal of solid particle impurities is subjected to multi-stage gas-liquid separation condensation to obtain liquid dichlorodihydrogen silicon and preliminarily separated gaseous helium; the preliminarily separated gaseous helium is subjected to multi-stage adsorption to remove residual organic impurities and inorganic impurities in the helium; the helium after removal of impurities is subjected to multi-stage membrane separation and purification to remove residual impurities to obtain high-purity helium.

[0009] In an implementable manner in combination with the first aspect, the filtering of the tail gas containing dichlorodihydrogen silicon and helium to remove solid particle impurities comprises: the tail gas containing dichlorodihydrogen silicon and helium is introduced into a buffer tank, pressurized by a pressurizing machine to 0.2-1.0 MPa, and then introduced into a 0.1 μm filter to remove solid particle impurities.

[0010] In an implementable manner in combination with the first aspect, the multi-stage gas-liquid separation condensation of the tail gas after removal of solid particle impurities to obtain liquid dichlorodihydrogen silicon and preliminarily separated gaseous helium comprises: the tail gas after removal of solid particle impurities is sent into a first gas-liquid separator, cooled to -30℃, to obtain liquid dichlorodihydrogen silicon which is sent into a first collection tank for storage; the tail gas after separation by the first gas-liquid separator is introduced into a second gas-liquid separator, cooled to -50℃, and subjected to gas-liquid separation again to obtain liquid dichlorodihydrogen silicon which is sent into a second collection tank for storage.

[0011] In an implementable manner in combination with the first aspect, the multi-stage adsorption of the preliminarily separated gaseous helium comprises: the gaseous helium is introduced into a multi-stage adsorption tower to remove organic impurities and inorganic impurities in stages; wherein the multi-stage adsorption tower is filled with 3A molecular sieve, modified activated carbon layer and activated carbon fiber layer from bottom to top in sequence, the activated carbon fiber is used to adsorb residual organic impurities in the helium, the modified activated carbon is used to adsorb part of the inorganic impurities in the helium, and the 3A molecular sieve is used to remove carbon and water small molecule impurities among the inorganic impurities to process carbon dioxide and water in the helium to <0.5 ppm.

[0012] In an implementable manner in combination with the first aspect, the adsorption temperature in the multi-stage adsorption tower is 25-50℃, and the gas flow rate is 0.3-0.8 m / s.

[0013] In combination with the first aspect, in an implementable manner, the impurity-removed helium is separated by multi-stage membranes, including: The impurity-removed helium enters a primary membrane separator for rough separation, so that most of the nitrogen and hydrocarbons in the organic impurities in the helium are separated out; The helium separated by the primary membrane separator is pressurized by a compressor and then enters a secondary membrane separator for refining and purification, so that the remaining impurity gas in the helium is separated out, and high-purity helium is obtained.

[0014] In combination with the first aspect, in an implementable manner, a hollow fiber membrane assembly is arranged in the primary membrane separator, and a high-performance composite membrane assembly is arranged in the secondary membrane separator.

[0015] In the second aspect, the embodiments of the present application further provide an electronic-grade dichlorodihydrogen silicon and helium recovery system for the electronic-grade dichlorodihydrogen silicon and helium recovery method, which includes, connected in sequence through pipelines, a buffer tank, a pressurizing machine, a filter, a multi-stage gas-liquid separator, a multi-stage adsorption tower, a primary membrane separator, a compressor, a secondary membrane separator, and a helium storage tank; the multi-stage gas-liquid separator is connected with a liquid dichlorodihydrogen silicon collection tank.

[0016] In the second aspect, the embodiments of the present application further provide that the multi-stage gas-liquid separator includes a primary gas-liquid separator and a secondary gas-liquid separator connected in series, the primary gas-liquid separator is connected with a first collection tank through a pipeline, and the secondary gas-liquid separator is connected with a second collection tank through a pipeline; the first collection tank and the second collection tank are connected in communication with the liquid dichlorodihydrogen silicon collection tank through a pipeline, and the liquid dichlorodihydrogen silicon condensed at different temperatures is collected in the respective collection tanks and then flows into the liquid dichlorodihydrogen silicon collection tank after being stabilized.

[0017] In the second aspect, the embodiments of the present application further provide that the recovery system further includes a regenerated adsorption tower, which is connected in parallel with the multi-stage adsorption tower between the multi-stage gas-liquid separator and the primary membrane separator, so that the recovery system is switched between the regenerated adsorption tower and the multi-stage adsorption tower.

[0018] The electronic-grade dichlorodihydrogen silicon and helium recovery method provided by the present application has the following beneficial effects compared with the prior art: (1) In view of the problem that the traditional high-temperature combustion method for treating tail gas consumes a large amount of energy, produces a large amount of high-temperature waste gas, and cannot recover helium and dichlorodihydrogen silicon and other useful resources, the present application replaces chemical combustion with physical separation, solving the problems of energy consumption and resource waste: By utilizing the significant boiling point difference between dichlorosilane (boiling point 8.2℃) and helium (boiling point -268.94℃), a multi-stage gas-liquid separation and condensation technology can achieve highly efficient separation of the two. This process does not require high-temperature combustion, does not produce high-temperature waste gas, does not consume a large amount of heat source, does not generate new pollutants due to incomplete combustion, and does not affect the recovery of helium and dichlorosilane. After the exhaust gas is condensed by a gas-liquid separator, liquid dichlorosilane is obtained directly, avoiding the loss of silicon source in the combustion method. Combined with subsequent purification processes, the purity of the recovered helium can reach electronic grade of 99.999% or higher, and can be directly reused in processes such as thin film deposition and silicon epitaxial growth, realizing a closed-loop cycle of helium. (2) For wet treatment processes, which generate high-concentration silicide and chloride wastewater, there is a serious risk of water and soil pollution. This invention completely eliminates secondary pollution through a fully dry process design: This invention removes impurities using dry methods such as filtration and adsorption. The multi-stage adsorption process efficiently captures residual organic and inorganic impurities, avoiding the high costs and pollution risks associated with wastewater treatment in wet processes. After the dichlorodihydrosilicon in the exhaust gas is condensed and recovered, the concentration of residual impurities in the helium gas has been significantly reduced. The subsequent adsorption-membrane separation combination can further reduce the impurity content. The final exhaust gas contains only trace amounts of inert gas, which fully complies with the stringent environmental protection regulations and requires no additional exhaust gas treatment facilities. (3) Electronic-grade products require helium purity of 99.999% or higher (GB / T4844-2011 standard), and traditional processes struggle to balance recovery rate and purity. This technical solution removes impurities from helium through multi-stage condensation, multi-stage adsorption, and multi-stage membrane separation, increasing helium purity to 99.9996%. Combined with a closed-loop reflux design, the total helium recovery rate can reach over 95%. While purifying helium, the dichlorosilane obtained from condensation can be further processed to meet electronic-grade standards, significantly improving the efficiency of resource recycling.

[0019] The method and system for recovering electronic-grade dichlorosilane and helium provided by this invention can achieve harmless treatment of exhaust gas, minimize exhaust gas emissions, and reduce energy consumption and environmental pollution. At the same time, it can efficiently recover useful substances in the exhaust gas and purify them to a purity standard that can be reused in the production of electronic-grade products, thereby achieving the purpose of resource recycling, reducing production costs, and improving the economic and environmental benefits of enterprises.

[0020] This invention is particularly effective in the efficient, energy-saving, and high-purity recovery of exhaust gases from electronic-grade dichlorosilane (SiH2Cl2) and helium, achieving harmless treatment and resource recycling of exhaust gases while meeting the environmental protection and cost control requirements of the electronics industry in the production process of high-purity products. Attached Figure Description

[0021] Figure 1 A schematic flowchart illustrating the method for recovering electronic-grade dichlorosilane and helium provided in an embodiment of the present invention; Figure 2 A schematic diagram of the process for recovering electronic-grade dichlorosilane and helium provided in an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Buffer tank; 2. Compressor; 3. Filter; 4. Primary gas-liquid separator; 5. Secondary gas-liquid separator; 6. Multistage adsorption tower; 7. Primary membrane separator; 8. Compressor; 9. Secondary membrane separator; 10. Helium storage tank; 11. First collection tank; 12. Second collection tank. Detailed Implementation

[0022] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0023] Please see Figure 1 and Figure 2 The present invention will now describe a method for recovering electronic-grade dichlorosilane and helium. The method for recovering electronic-grade dichlorosilane and helium includes the following steps: S001, the tail gas containing dichlorosilane and helium is filtered to remove solid particulate impurities. S002, utilizing the difference in boiling points between dichlorosilane and helium, the tail gas after removing solid particulate impurities is condensed through multi-stage gas-liquid separation to obtain liquid dichlorosilane and preliminarily separated gaseous helium. S003, the initially separated gaseous helium is subjected to multi-stage adsorption to remove residual organic and inorganic impurities in the helium; S004, the helium gas after removing impurities is purified by multi-stage membrane separation to remove residual impurities and obtain high-purity helium gas.

[0024] In some embodiments, see Figure 2 Before step S001, the exhaust gas containing dichlorosilane and helium needs to be introduced into buffer tank 1, pressurized to 0.2-1.0 MPa by pressurizer 2, and then enters 0.1μm high efficiency filter 3 to remove solid particulate impurities greater than or equal to 0.1μm, so as to avoid the risk of subsequent equipment blockage and contamination of semiconductor wafers.

[0025] In step S002, the difference in boiling points between dichlorosilane and helium is utilized to perform multi-stage gas-liquid separation on the filtered tail gas by gradually reducing the temperature to different ranges, thereby achieving the separation of dichlorosilane and helium.

[0026] Specifically, the boiling point of dichlorodihydrosilicon is 8.2℃, while that of helium is -268.94℃, a significant difference exists between the two. Therefore, in the first-stage gas-liquid separator 4, the exhaust gas is cooled to approximately -30℃, causing the dichlorodihydrosilicon to condense into a liquid state. This liquid substance is then separated out by the first-stage gas-liquid separator 4. The exhaust gas separated by the first-stage gas-liquid separator 4 enters the second-stage gas-liquid separator 5, where the temperature is further reduced to -50℃, causing the remaining dichlorodihydrosilicon to liquefy and undergo gas-liquid separation again.

[0027] This process allows dichlorosilane to fully condense, while the helium gas remains in a gaseous state. The condensed liquid dichlorosilane can be stored in a liquid collection tank for subsequent treatment or reuse. Thus, the recovery of dichlorosilane from the exhaust gas is achieved.

[0028] In step S003, see Figure 2 The main process involves drying, adsorbing, and purifying the initially separated helium through multi-stage adsorption, removing moisture and most impurities to achieve preliminary purification of the helium.

[0029] The multi-stage adsorption tower 6 is filled from bottom to top with a 3A molecular sieve, a modified activated carbon layer, and an activated carbon fiber layer. Preliminarily purified helium enters the multi-stage adsorption tower 6, first passing through the activated carbon fiber to adsorb residual dichlorosilane and some hydrocarbon organic impurities, such as methane and ethane; then passing through the middle modified activated carbon layer to remove some inorganic impurities such as CO2 and CO; finally, passing through the 3A molecular sieve to further remove small molecule impurities such as carbon and water from the helium. Because the moisture content of the helium needs to be reduced to below 0.5 ppm before entering the subsequent membrane separation process, it is necessary to protect downstream equipment or pipelines from ice blockage.

[0030] To explain, 3A molecular sieve, also known as 3A zeolite molecular sieve, is an alkali metal aluminosilicate with the chemical formula 2 / 3K₂O·1 / 3Na₂O·Al₂O₃·2SiO₂·9 / 2H₂O. Its effective pore size is 3 Å (0.3 nanometers), specifically designed to adsorb water molecules with a diameter smaller than 3 Å. It repels large molecules such as ethane, thus effectively removing moisture from helium gas.

[0031] The adsorption temperature in the multi-stage adsorption tower 6 is 25-50℃, and the gas flow rate is 0.3-0.8m / s, achieving a good adsorption effect.

[0032] In this application, two parallel multi-stage adsorption towers 6 are provided, which can be periodically regenerated by switching between high-temperature desorption and low-pressure desorption to extend the service life of the adsorbent and ensure the continuity of the recovery process.

[0033] For example, the regeneration conditions using high-temperature desorption are as follows: purging with hot nitrogen gas at 150°C, with a regeneration cycle of 4-8 hours.

[0034] In step S004, see Figure 2 The main method utilizes the different affinities of helium and its impurities with the membrane material under pressure difference to purify and refine helium, obtaining 99.999% high-purity helium.

[0035] The working principle of membrane separation is as follows: First, there's adsorption and dissolution: the mixed gas comes into contact with the membrane surface under pressure. Due to intermolecular forces between gas molecules and the membrane material, the gas is adsorbed onto the membrane surface and dissolves into the membrane material. Gases with small molecular sizes and high affinity for membrane materials dissolve more easily. Helium (He), because of its extremely small molecules and inert nature, has weak interactions with most polymer membranes, but due to its extremely small size, it can easily squeeze into the gaps between the molecular chains of the membrane material.

[0036] Secondly, there is diffusion: gas molecules dissolved within the membrane move from the high-pressure side to the low-pressure side, driven by the concentration difference across the membrane (driven by the pressure difference). The speed of this movement (diffusion rate) depends on the size and shape of the molecules. The smaller and lighter the molecules, the faster the diffusion rate. Helium is one of the smallest and lightest molecules of all gases, therefore its diffusion rate within the membrane is much faster than that of larger molecules such as nitrogen (N2) and methane (CH4).

[0037] Finally, desorption occurs: gas molecules that have diffused to the other side of the membrane (the low-pressure side) are released from the membrane material and become permeate gas.

[0038] After multi-stage adsorption, the impurities in helium mainly include small amounts of nitrogen and methane. Since the diameter of helium molecules (approximately 0.26 nm) is much smaller than that of common impurity gases such as nitrogen (0.364 nm) and methane (0.38 nm), helium molecules are more easily dissolved in the membrane material and diffuse through the membrane pores to the other side of the membrane under the drive of the concentration gradient, thereby achieving separation from other gases.

[0039] This invention employs a two-stage membrane separation process. After passing through the first-stage membrane separator 7, most of the nitrogen and hydrocarbon impurities in organic impurities such as methane and ethane are separated. The helium is then concentrated 7-10 times before entering the permeate gas stage, and then passes through the more selective second-stage membrane separator 9 to achieve the purification of the helium.

[0040] Selection of primary membrane separator 7: The helium gas after multi-stage adsorption has a high impurity gas content and high partial pressure. Therefore, primary membrane separator 7 needs to be a membrane with high permeation flux, good mechanical strength, and strong antifouling ability, such as hollow fiber membrane modules made of polyimide or polysulfone. It has moderate selectivity for helium but a large throughput.

[0041] The primary membrane separation process is as follows: Helium gas is pressurized to a certain pressure (e.g., 3.0 MPa) and enters the first-stage membrane separator 7. Under pressure, helium gas will preferentially permeate through the membrane and reach the low-pressure side; while most impurities such as nitrogen, methane and ethane cannot permeate through the membrane due to their extremely slow permeation rate and are discharged from the high-pressure side outlet of the first-stage membrane separator 7.

[0042] After passing through the first-stage membrane separator 7, the helium concentration in the permeate gas is concentrated by about 7-10 times, but it still contains a considerable proportion of impurities such as nitrogen and methane.

[0043] Selection of Secondary Membrane Separator 9: The goal of the secondary membrane separator 9 is to further purify the helium after primary concentration to 99.999% high-purity helium. At this point, the total gas volume has been reduced, the helium concentration is high, and the impurity partial pressure is low. Therefore, a highly selective membrane can be selected, such as a membrane based on polytrimethylsilylpropyne (PTMSP) or other high-performance composite materials, to further separate the helium from other residual impurity gases, thereby obtaining high-purity helium.

[0044] Secondary membrane separation process: The permeate gas pressure in the first-stage membrane separator is relatively low. After being pressurized by the compressor 8 (e.g., to 2.0 MPa), it enters the second-stage membrane separator 9.

[0045] In highly selective secondary membranes, helium can pass through rapidly due to its extremely small molecular size, while residual impurities such as nitrogen and methane are strictly blocked.

[0046] After two-stage purification and separation, high-purity helium gas with a purity of 99.999% can be obtained from the low-pressure side of the membrane.

[0047] The exhaust gas from the recovery of electronic-grade dichlorosilane and helium in this invention contains total hydrocarbons, primarily organic impurities such as methane, ethane, and residual solvents; and inorganic impurities mainly consisting of carbon monoxide, carbon dioxide, nitrogen, and oxygen; among which carbon and water are small molecule impurities. This invention utilizes corresponding treatment methods tailored to the characteristics of different substances in the exhaust gas to remove impurities in a graded manner, and can efficiently recover dichlorosilane and helium.

[0048] After the exhaust gas is treated using the recovery method provided by this invention, the purified helium is monitored in real time by a mass flow controller (MFC) and a laser gas analyzer (detection accuracy 0.1ppm), and impurities in the helium are detected. The detection results are shown in Table 1 below: Table 1

[0049] In Table 1, GC represents gas chromatography; B indicates basic qualification, and G represents qualification; the moisture analyzer refers to a dew point meter and a Karl Fischer moisture analyzer; and the trace O2 is measured by an electrochemical sensor and a laser spectroscopy method.

[0050] The data in the table directly proves that the core quality and impurity control of the recovered products meet or even exceed the preset requirements, as detailed below: (1) Helium purity meets and exceeds the standard: total purity ≥ 99.9997% (5.7N grade), which meets the stringent standards for industrial-grade high-purity materials. The fact that the target product is purified to meet the design expectations even without an upper limit setting indicates that the purification effect of the target product has met the design expectations. (2) Extreme control of key impurities: The actual values ​​of key impurities such as water (≤0.02ppm) and oxygen (≤0.01ppm), which are most harmful to product stability and downstream applications, are all lower than the control limit and are marked as G, which proves the system's ability to remove impurities. (3) Other impurities are fully compliant: Nitrogen (≤1.00ppm), total hydrocarbons (such as methane, ethane and solvent residues ≤0.10ppm), CO2+CO (≤0.10ppm) and other major impurities, although the control upper limit is slightly higher than that of key impurities (due to the higher difficulty of removal), the actual values ​​are all within the standard and the status is marked as B (generally qualified), achieving compliance control of all impurities without any risk of omission. The structural rationality and operational effectiveness of the recycling system were verified: Firstly, the adsorption and separation efficiency is excellent: the dual achievement of high purity and low impurities proves that the combination of multi-stage adsorption towers and regeneration adsorption towers can effectively intercept different types of impurities such as moisture, oxygen, and hydrocarbons, and the selectivity and adsorption capacity of the adsorbent meet the design requirements.

[0051] Secondly, the switching of regeneration mode is reliable: no indicators exceeded the standard (especially the core impurities were consistently within the standard), indicating that the "dual-tower alternating adsorption-regeneration" mode avoids impurity penetration caused by adsorption saturation, realizes continuous purification without downtime, and ensures the stability of product quality. Third, the multi-stage gas-liquid separation + adsorption process effectively removes the vast majority of impurities, achieving high-purity helium recovery.

[0052] Fourth, the detection methods are highly adaptable: the combination of specialized instruments (moisture analyzer, trace O2 analyzer) and gas chromatography (GC) ensures accurate quantification of trace / ultra-micro impurities and verifies the reliability of the detection data, providing reliable support for quality conclusions.

[0053] The stringency of the indicators suggests that the products of this recovery system can meet the requirements of scenarios with extremely high requirements for material purity and impurity control, proving that the system has practical application value. With a total purity of 5.7N and impurity control below ppm, it meets the quality requirements of the electronics industry (such as semiconductor manufacturing), high-end chemicals (such as catalyst raw materials), and standard gas preparation, and can replace high-cost virgin high-purity materials, enabling resource recycling and reuse.

[0054] The following is an explanation of the impurity control parameters in Table 1: Regarding moisture: Moisture content is expressed in ppm (parts per million) by volume, with an upper limit of ≤0.02ppm. If the actual value is lower than this upper limit, the state is G, and the detection method is a moisture meter (such as a dew point meter or Karl Fischer moisture meter).

[0055] Moisture is one of the most common and harmful impurities in industrial recycling. The strict limits on moisture content are due to: ① preventing moisture from reacting with the target product (e.g., hydrolysis, oxidation), leading to product deterioration; ② preventing moisture from condensing under low temperature or high pressure conditions, causing equipment corrosion and pipeline blockage (especially applicable to gas recovery systems); ③ meeting the requirements of downstream processes for an anhydrous environment (e.g., moisture in electronic component manufacturing can cause product defects, and moisture in chemical reactions can affect catalyst activity). Meeting this standard indicates that the adsorption unit (multi-stage adsorption tower + regeneration adsorption tower) of the recovery system has a strong adsorption capacity for trace amounts of moisture.

[0056] Regarding oxygen: The upper limit of oxygen content is ≤0.01ppm. The actual value is lower than the upper limit. The state is G. The detection method is trace O2 (such as electrochemical sensor, laser spectroscopy).

[0057] The presence of oxygen can cause two types of problems: ① Oxidation reaction risk (e.g., when the target product is an easily oxidized gas / solvent, oxygen can cause product deterioration, aging, or even safety hazards); ② Affect product performance (e.g., in semiconductor manufacturing, trace amounts of oxygen can cause chip oxidation defects; oxygen impurities in high-purity gases can reduce the purity level of materials).

[0058] The stringent upper limit of 0.01 ppm for oxygen content demonstrates the system's ability to deeply remove oxidizing impurities and verifies the effectiveness of the specialized adsorbent in the adsorption tower.

[0059] Regarding nitrogen: The upper limit of nitrogen content is ≤1.00ppm. If the actual value is lower than the upper limit, the status is Class B, and the detection method is GC (gas chromatography).

[0060] Nitrogen is usually an inert gas, but when it exists as an impurity, the consequences are: ① dilution of the purity of the target product (especially in scenarios requiring high purity, nitrogen is the main dilutive impurity); ② impact on process stability (for example, in some catalytic reactions, the accumulation of inert gases can reduce the reaction rate).

[0061] The upper limit of nitrogen index (1 ppm) is higher than that of oxygen, water and other indicators. This is because nitrogen molecules have a stable structure and it is difficult for adsorbents to selectively adsorb nitrogen. The control level of 1 ppm is already a routine and stringent standard for industrial high-purity recovery.

[0062] Regarding total hydrocarbons (THC): the upper limit of content is ≤0.10ppm. If the actual value is lower than the upper limit, the state is B, and the detection method is GC.

[0063] Hydrocarbons (such as methane, ethane, and solvent residues) are organic impurities that may remain during the recycling process. Their hazards include: ① contaminating the target product (e.g., hydrocarbons in high-purity gases can affect combustion efficiency and lead to carbon buildup); ② posing safety risks (some hydrocarbons are flammable and explosive, and may accumulate to the explosion limit in a closed system); ③ failing to meet environmental protection requirements (if the recycled product is used for emission or secondary utilization, excessive hydrocarbons will cause pollution).

[0064] The fact that this indicator meets the standard proves that the multi-stage adsorption tower has sufficient adsorption capacity for organic impurities, and that the desorption and regeneration process of the regeneration adsorption tower can effectively remove the adsorbed hydrocarbons and avoid the accumulation of impurities in the adsorption-regeneration cycle.

[0065] Regarding carbon dioxide + carbon monoxide: The upper limit of the total content of CO2 and CO is ≤0.10ppm. If the actual value is lower than the upper limit, the state is B, and the detection method is GC.

[0066] These two gases are acidic oxides / reducing impurities, and their hazards are manifested in the following ways: ① Corrosion of equipment (CO2 dissolves in water to form carbonic acid, which corrodes pipes and the inner walls of equipment); ② Affecting product quality; in the electronics industry, CO can cause oxidation of metal plating); ③ Environmental compliance risks (CO is a toxic gas, and exceeding emission standards will violate environmental standards).

[0067] The reason for combining the detection of CO2 and CO is that they often coexist in industrial exhaust gases (such as chemical reaction exhaust gases and combustion exhaust gases), and gas chromatography can achieve separation and quantification through the same detection channel. Combining the control of indicators simplifies the detection process and can comprehensively cover the control requirements of carbon oxide impurities.

[0068] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0069] Based on the same inventive concept, embodiments of this application also provide an electronic-grade dichlorosilane and helium recovery system, see [link to relevant documentation]. Figure 2 The method for recovering electronic-grade dichlorosilane and helium includes a buffer tank 1, a compressor 2, a filter 3, a multi-stage gas-liquid separator, a multi-stage adsorption tower 6, a primary membrane separator 7, a compressor 8, a secondary membrane separator 9, and a helium storage tank 10 connected in sequence by pipelines; the multi-stage gas-liquid separator is connected to a liquid dichlorosilane collection tank.

[0070] The system provided by this invention can recover the exhaust gas of electronic-grade dichlorosilane and helium, which can minimize exhaust gas emissions, reduce energy consumption and environmental pollution. At the same time, it can efficiently recover useful substances in the exhaust gas and purify them to a purity standard that can be reused in the production of electronic-grade products, thereby achieving the purpose of resource recycling, reducing production costs, and improving the economic and environmental benefits of enterprises.

[0071] In some embodiments, see Figure 2 The multi-stage gas-liquid separator includes a first-stage gas-liquid separator 4 and a second-stage gas-liquid separator 5 connected in series. The first-stage gas-liquid separator 4 is connected to a first collection tank 11 via a pipeline, and the second-stage gas-liquid separator 5 is connected to a second collection tank 12 via a pipeline. The first collection tank 11 and the second collection tank 12 are connected to a liquid dichlorosilane collection tank via pipelines. Liquid dichlorosilane condensed to different temperatures is stabilized in its respective collection tank and then flows into the liquid dichlorosilane collection tank for subsequent treatment or reuse.

[0072] In some embodiments, see Figure 2 The recovery system also includes a regeneration adsorption tower, which is connected in parallel with the multi-stage adsorption tower 6 between the multi-stage gas-liquid separator and the primary membrane separator 7, allowing the recovery system to switch between the regeneration adsorption tower and the multi-stage adsorption tower 6. The regeneration adsorption tower and the multi-stage adsorption tower 6 have the same internal structure and function, and are connected in parallel within the recovery system (see reference). Figure 2 However, no attached diagram of the regeneration adsorption tower was provided.

[0073] The recycling system provided by this invention is equipped with two adsorption towers, which can be periodically switched for regeneration to ensure continuous recycling and improve recycling efficiency, as detailed below: When a multi-stage adsorption tower needs to be regenerated due to adsorption saturation, it can be directly switched to the regeneration adsorption tower for operation without interrupting the feeding and separation process of the entire recovery system. This ensures the continuity of material recovery in industrial production and is especially suitable for continuous production scenarios with high requirements for operational stability, significantly reducing capacity loss and material waste caused by downtime.

[0074] This avoids the decrease in adsorption capacity caused by long-term saturation and lack of treatment of the adsorbent, and ensures that each set of towers is in the optimal adsorption state when put into use, thereby improving the adsorption selectivity and recovery rate of the target components.

[0075] In addition, the parallel design of the two towers can prevent the entire system from shutting down due to the failure of a single tower, thus improving the operational reliability of the recycling system and reducing production risks.

[0076] The recycling system provided by this invention is equipped with temperature sensors, pressure sensors, level gauges, and electrically controlled valves. It employs a DCS (Distributed Control System) automatic control system, enabling real-time monitoring and automatic adjustment of process parameters, reducing manual intervention, and improving system stability and reliability. This DCS automatic control system is a type of industrial automation control system based on a distributed architecture. It is a conventional technical means and is not the inventive point or scope of protection of this invention; therefore, it will not be described in detail herein.

[0077] The beneficial effects of the electronic-grade dichlorosilane and helium recovery system and method provided by this invention are as follows: (1) High recovery rate: Through a series of steps such as condensation separation, adsorption purification and membrane separation, the helium recovery rate can reach more than 95%, which greatly improves the utilization rate of helium and reduces production costs.

[0078] (2) High purity: After being processed by the recycling system of the present invention, the purity of helium can reach more than 99.999%, which meets the strict requirements of high-end fields such as semiconductor manufacturing for helium purity, and ensures the stability of the process and product quality.

[0079] (3) Environmental protection and energy saving: It realizes the recycling of helium, reduces helium emissions, and conforms to the concept of environmental protection.

[0080] (4) Cost-effectiveness: It reduces the need for purchasing new helium, thereby lowering the company's operating costs. Furthermore, the equipment investment in the recovery system can be quickly recouped through the recycling of helium during long-term operation, demonstrating good cost-effectiveness.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the recovery of electronic grade dichlorodihydrogen silane and helium gas, characterized in that, The recovery method comprises: The tail gas containing dichlorodihydrogen silicon and helium is filtered to remove solid particle impurities; The tail gas after removing solid particle impurities is condensed by multi-stage gas-liquid separation to obtain liquid dichlorodihydrogen silicon and preliminarily separated gaseous helium; The preliminarily separated gaseous helium is adsorbed by multi-stage adsorption to remove residual organic and inorganic impurities in the helium; The helium after removing impurities is separated by multi-stage membrane separation to remove residual impurities to obtain high-purity helium.

2. The process of claim 1, wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, The tail gas containing dichlorodihydrogen silicon and helium is introduced into a buffer tank (1), pressurized by a pressurizing machine (2) to 0.2-1.0 MPa, and then enters a 0.1 μm filter (3) to remove solid particle impurities. The tail gas after removing solid particle impurities is sent into a first-stage gas-liquid separator (4) to be cooled to -30 ℃ to obtain liquid dichlorodihydrogen silicon, which is stored in a first collection tank (11); 3. The process of claim 1 wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, The tail gas after the first-stage gas-liquid separator (4) is cooled to -50 ℃ to be separated again to obtain liquid dichlorodihydrogen silicon, which is stored in a second collection tank (12). The preliminarily separated gaseous helium is adsorbed by multi-stage adsorption to remove residual organic and inorganic impurities in the helium; The multi-stage adsorption tower (6) is filled with 3A molecular sieve, modified activated carbon layer and activated carbon fiber from bottom to top, the activated carbon fiber is used to adsorb residual organic impurities in the helium, the modified activated carbon is used to adsorb part of inorganic impurities in the helium, and the 3A molecular sieve is used to remove carbon and water small molecule impurities in the inorganic impurities to process carbon dioxide and water in the helium to be less than 0.5 ppm.

4. The process of claim 1 wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, The adsorption temperature in the multi-stage adsorption tower (6) is 25-50 ℃, and the gas flow rate is 0.3-0.8 m / s. The helium after removing impurities is separated by multi-stage membrane separation to remove residual impurities to obtain high-purity helium. The first-stage membrane separator (7) is provided with a hollow fiber membrane assembly, and the second-stage membrane separator (9) is provided with a high-performance composite membrane assembly.

5. The process of claim 4 wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, ​ 6. The process of claim 1 wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, ​ ​ ​ 7. The process of claim 6 wherein the electronic grade dichlorodihydrogen silane and helium gas are recovered by, ​ 8. A recovery system of electronic grade dichlorodihydrogen silane and helium gas for the recovery method of electronic grade dichlorodihydrogen silane and helium gas as claimed in any one of claims 1 to 7, characterized by, ​ 9. The electronic grade dichlorodihydrogen silane and helium gas recovery system of claim 8 wherein, The multi-stage gas-liquid separator comprises a first-stage gas-liquid separator (4) and a second-stage gas-liquid separator (5) connected in series, the first-stage gas-liquid separator (4) is connected to a first collection tank (11) through a pipeline, and the second-stage gas-liquid separator (5) is connected to a second collection tank (12) through a pipeline; the first collection tank (11) and the second collection tank (12) are connected to the liquid dichlorodihydrogen silicon collection tank through a pipeline, and the liquid dichlorodihydrogen silicon condensed to different temperatures is collected in the respective collection tanks and then collected into the liquid dichlorodihydrogen silicon collection tank after being stabilized.

10. The electronic grade dichlorodihydrogen silane and helium gas recovery system of claim 8 wherein, The recovery system further comprises a regenerated adsorption tower connected in parallel with the multi-stage adsorption tower (6) between the multi-stage gas-liquid separator and the first-stage membrane separator (7), so that the recovery system switches between the regenerated adsorption tower and the multi-stage adsorption tower (6).

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