An electronic grade acetylene purification system based on double membrane method

Abstract

The utility model relates to an electronic grade acetylene purification system based on double membrane method, it includes according to material flow direction connection's small molecule separation membrane subassembly, macromolecular separation membrane subassembly, absorption tower and analysis tower, wherein small molecule separation membrane subassembly's retentate side is connected with macromolecular separation membrane subassembly's feed side, macromolecular separation membrane subassembly's permeation side is connected with absorption tower's feed side, the film in small molecule separation membrane subassembly is molecular sieve membrane, selects one or more in STT, DDR, CHA type, the film in macromolecular separation membrane subassembly is molecular sieve membrane, selects one or more in MFI type, LTA type, T type, the utility model discloses that double membrane method separation technology and solvent absorption process are coupled, effectively remove various impurities in industrial grade acetylene, can realize the production of electronic grade acetylene, the acetylene purity of this method purification reaches 99.99999% or above, reaches the highest purity level of the present disclosure report, satisfies the strict requirement of electronic industry etc. to high purity completely.

Description

Technical Field

[0001] This utility model relates to an acetylene purification system, specifically a system based on the coupling of a dual-membrane method and a solvent absorption method to remove impurities from acetylene to the electronic level, belonging to the field of gas separation. Background Technology

[0002] Electronic specialty gases are core materials in semiconductor manufacturing, often referred to as the "lifeblood of the electronics industry." They are widely used in critical processes such as photolithography, etching, and doping of chips, and their purity directly determines the yield and performance of integrated circuits. Among them, electronic-grade acetylene with a purity higher than 99.99% is a key electronic specialty gas and is widely used in chemical vapor deposition (CVD) processes in semiconductor manufacturing. However, my country's self-sufficiency rate in this field is low. The annual demand for electronic-grade acetylene exceeds 2,000 tons, but the self-sufficiency rate is less than 10%, making it highly dependent on imports.

[0003] Industrial acetylene production mainly employs the calcium carbide method and thermal cracking method. The acetylene produced typically contains various impurities such as hydrogen, oxygen, argon, nitrogen, carbon dioxide, methane, ethane, ethylene, propane, and propylene. However, these impurities have a significant impact on the purity of acetylene and its downstream applications, especially in the production of electronic-grade acetylene, where impurity control is particularly stringent. Cryogenic distillation is a commonly used gas separation method in industry, but its application is limited due to the safety hazard of explosion after acetylene liquefaction at low temperatures. Currently, many companies at home and abroad are attempting to purify acetylene using adsorption and solvent absorption methods (e.g., CN113563151B, CN115246760A, CN117658732B). However, these processes still have the following shortcomings: (1) the impurity content in the purified acetylene is relatively high; (2) the process has high energy consumption and a large footprint; and (3) the adsorbent is prone to deactivation and has a short service life.

[0004] Membrane separation technology offers significant advantages in gas separation. The separation process involves no phase change, resulting in substantial energy reduction and making it a highly efficient and energy-saving method. Membrane separation equipment is characterized by its compact structure and small footprint. This technology enables continuous separation and online operation, minimizing downtime and improving production efficiency. While organic membranes have achieved industrial application in gas separation, they suffer from problems such as plasticization, aging, and chemical degradation, leading to decreased separation performance, shortened lifespan, and higher maintenance costs. Compared to organic membranes, inorganic membranes offer advantages such as corrosion resistance and high mechanical strength, enabling stable operation under more complex conditions and providing higher separation efficiency.

[0005] Existing technologies have disclosed the use of membrane separation for acetylene purification; however, these devices are limited to laboratory research, and the commonly used test gases are limited to binary gases containing acetylene and carbon dioxide, with a carbon dioxide content greater than 5%, which is insufficient to cover actual working conditions. Because industrial-grade acetylene contains various small and large molecular impurities, and the impurity content is generally at the ppm level, current methods, such as using membrane separation technology alone or simply coupling membrane separation with other purification technologies, cannot purify industrial-grade acetylene into electronic-grade acetylene.

[0006] Therefore, there is an urgent need to optimize existing membrane separation methods for preparing electronic-grade acetylene. Utility Model Content

[0007] This invention addresses the challenge of multi-component impurities coexisting in industrial-grade acetylene, with impurity levels at the ppm level, by proposing a dual-membrane method for preparing electronic-grade acetylene. The inorganic membrane used possesses excellent corrosion resistance, high mechanical strength, and a long service life, enabling long-term stable operation under complex working conditions.

[0008] This invention discloses an electronic-grade acetylene purification system based on a dual-membrane method. It includes a small-molecule separation membrane module, a large-molecule separation membrane module, an absorption tower, and a desorption tower connected according to the material flow direction. The permeate side of the small-molecule separation membrane module is connected to the feed side of the large-molecule separation membrane module, and the permeate side of the large-molecule separation membrane module is connected to the feed side of the absorption tower. The membrane in the small-molecule separation membrane module is a molecular sieve membrane, selected from one or more of the STT, DDR, and CHA types. The membrane in the large-molecule separation membrane module is a molecular sieve membrane, selected from one or more of the MFI, LTA, and T types. The small-molecule separation membrane module is used to remove small-molecule impurities from industrial-grade acetylene, and the large-molecule separation membrane module is used to remove large-molecule impurities from industrial-grade acetylene. Here, small-molecule impurities refer to impurities with a permeation rate faster than acetylene during membrane separation, while large-molecule impurities refer to impurities with a permeation rate slower than acetylene during membrane separation. The small molecule impurities include hydrogen, oxygen, argon, nitrogen, and carbon dioxide, while the large molecule impurities include methane, ethane, ethylene, propane, and propylene.

[0009] Preferably, the membrane type in the small molecule separation membrane assembly and the macromolecule separation membrane assembly is one or more of the following: flat sheet membrane, tubular membrane, multi-channel membrane, or hollow fiber membrane.

[0010] Preferably, the solvent in the absorption tower is one of liquid ammonia, dimethylformamide (DMF), N-methylpyrrolidone (NMP), methanol, liquid ammonia, and acetone.

[0011] Preferably, a first compressor is provided upstream of the small molecule separation membrane assembly, and a second compressor is provided between the macromolecule separation membrane assembly and the absorption tower.

[0012] Preferably, the middle section of the absorption tower is connected to the top of the absorption tower via a first hydraulic pump and a first heat exchanger.

[0013] Preferably, the bottom of the absorption tower is connected to the desorption tower via a second hydraulic pump and a second heat exchanger, and the bottom of the desorption tower is connected to the top of the absorption tower via a second heat exchanger, a third hydraulic pump, and a third heat exchanger.

[0014] Preferably, a reboiler is connected to the bottom of the stripping column.

[0015] Preferably, the top of the analytical tower is connected to the gas-liquid separator via a fourth heat exchanger, the top of the gas-liquid separator is provided with an acetylene-rich gas outlet, and the bottom of the gas-liquid separator is connected to the analytical tower via a fourth hydraulic pump 16.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] First, this invention couples a dual-membrane separation technology with a solvent absorption process, effectively removing various impurities from industrial-grade acetylene and enabling the production of electronic-grade acetylene. The acetylene purified by this method achieves a purity of over 99.99999%, reaching the highest purity level reported to date, fully meeting the stringent high-purity requirements of the electronics industry and other sectors.

[0018] Secondly, this invention couples membrane separation technology with solvent absorption process, further reducing energy consumption in the solution desorption process. This significantly reduces overall operating costs while achieving efficient purification, combining good economic efficiency and sustainability, and is suitable for the preparation of electronic-grade acetylene.

[0019] Furthermore, compared to traditional organic membranes, the molecular sieve membrane used in this invention has advantages such as corrosion resistance and high mechanical strength, enabling stable operation in complex working environments. These characteristics significantly improve the service life of the membrane module, avoid problems such as aging and plasticization that are common in organic membranes, and reduce the frequency and cost of equipment maintenance. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow of Embodiment 1 of this utility model;

[0021] Figure 2 This is a schematic diagram of the process flow of Embodiment 2 of this utility model;

[0022] Among them, 1-small molecule separation membrane module, 2-large molecule separation membrane module, 3-absorption tower, 4-desorption tower, 5-first compressor, 6-second compressor, 7-first hydraulic pump, 8-first heat exchanger, 9-second hydraulic pump, 10-second heat exchanger, 11-third hydraulic pump, 12-third heat exchanger, 13-reboiler, 14-fourth heat exchanger, 15-gas-liquid separator, 16-fourth hydraulic pump. Detailed Implementation

[0023] Example 1

[0024] Figure 1 This is a schematic diagram of the process in this embodiment, as shown below. Figure 1 As shown, the electronic-grade acetylene purification system based on the dual-membrane method in this embodiment includes a small molecule separation membrane module 1, a large molecule separation membrane module 2, an absorption tower 3, and a desorption tower 4 connected according to the material flow direction. The permeate side of the small molecule separation membrane module 1 is connected to the feed side of the large molecule separation membrane module 2, and the permeate side of the large molecule separation membrane module 2 is connected to the feed side of the absorption tower 3. The small molecule separation membrane module 1 is used to remove small molecule impurities from industrial-grade acetylene, and the large molecule separation membrane module 2 is used to remove large molecule impurities from industrial-grade acetylene. The membrane in the small molecule separation membrane module 1 is a molecular sieve membrane, selected from one or more of the STT, DDR, and CHA types. The membrane in the large molecule separation membrane module 2 is a molecular sieve membrane, selected from one or more of the MFI, LTA, and T types. The membrane types of the small molecule separation membrane module 1 and the large molecule separation membrane module 2 are selected from one or more of the flat sheet membrane, tubular membrane, multi-channel membrane, or hollow fiber membrane.

[0025] Example 2

[0026] Figure 2 This is a detailed process flow diagram of this embodiment, such as... Figure 2 As shown, the electronic-grade acetylene purification system based on the dual-membrane method in this embodiment includes a small molecule separation membrane module 1, a large molecule separation membrane module 2, an absorption tower 3, and a desorption tower 4 connected according to the material flow direction. The permeate side of the small molecule separation membrane module 1 is connected to the feed side of the large molecule separation membrane module 2, and the permeate side of the large molecule separation membrane module 2 is connected to the feed side of the absorption tower 3. The small molecule separation membrane module 1 is used to remove small molecule impurities from industrial-grade acetylene, and the large molecule separation membrane module 2 is used to remove large molecule impurities from industrial-grade acetylene. The membrane in the small molecule separation membrane module 1 is an STT molecular sieve hollow fiber membrane, and the membrane in the large molecule separation membrane module 2 is an MFI molecular sieve hollow fiber membrane.

[0027] In addition, a first compressor 5 is installed upstream of the first small molecule separation membrane assembly 1, and a second compressor 6 is located between the macromolecule separation membrane assembly 2 and the absorption tower 3. The solvent is cooled and returned to the top of the absorption tower 3 via a first hydraulic pump 7 and a first heat exchanger 8 at the middle end. The bottom of the absorption tower 3 is connected to the desorption tower 4 via a second hydraulic pump 9 and a second heat exchanger 10 to transport the saturated acetylene-rich liquid to the top of the desorption tower 4. The bottom of the desorption tower 4 is connected to the top of the absorption tower via a second heat exchanger 10, a third hydraulic pump 11, and a third heat exchanger 12 to cool the desorbed lean acetylene liquid and transport it to the top of the absorption tower for recycling. A reboiler is also connected to the bottom of the desorption tower 4. The top of the desorption tower 4 is connected to a gas-liquid separator 15 via a fourth heat exchanger 14. The top of the gas-liquid separator 15 has an acetylene-rich gas outlet, and the bottom of the gas-liquid separator 15 is connected to the desorption tower 4 via a fourth hydraulic pump 16.

[0028] Example 3

[0029] A method for purifying electronic-grade acetylene using a dual-film method employing the system of Example 2 includes the following steps:

[0030] Industrial-grade acetylene enters the small molecule separation membrane module, where most of the small molecule impurities in the industrial-grade acetylene are removed by permeation.

[0031] The industrial-grade acetylene processed in step (1) continues to enter the macromolecular separation membrane module, where most of the macromolecular impurities in the industrial-grade acetylene are retained and removed.

[0032] The industrial-grade acetylene processed in step (2) continues to enter the absorption tower. The acetylene gas in the industrial-grade acetylene is absorbed by the solvent in the absorption tower, and other non-condensable gases are discharged through the top of the absorption tower.

[0033] (4) The acetylene-rich liquid at the bottom of the absorption tower enters the desorption tower for desorption, thereby obtaining electronic-grade acetylene product. The industrial-grade acetylene has a purity of 99.92%, a hydrogen content of 85 ppm, an oxygen content of 166 ppm, an argon content of 122 ppm, a nitrogen content of 149 ppm, a carbon dioxide content of 5.3 ppm, a methane content of 103 ppm, an ethane content of 83 ppm, an ethylene content of 14 ppm, a propane content of 11 ppm, and a propylene content of 12 ppm. The small molecule separation membrane module operates at a pressure of 2.0 MPa and a temperature of 25°C, as does the large molecule separation membrane module. The solvent in the absorption tower is dimethylformamide (DMF), and the absorption tower operates at a pressure of 2.0 MPa and a temperature of 25°C. The desorption tower operates at a pressure of 2.0 MPa and a temperature of 200°C. After processing, the final electronic-grade acetylene obtained reaches a purity of 99.999995%, with the contents of hydrogen, oxygen, argon, nitrogen, methane, ethane, ethylene, and propylene all below 0.1 ppb, carbon dioxide at 37 ppb, and propane at 14 ppb.

[0034] Example 4

[0035] This embodiment uses the same method as Example 3, except that: the membrane material used in the small molecule separation membrane module is a DDR type molecular sieve membrane, and the operating pressure is 1.0 MPa. The membrane material used in the macromolecule separation membrane module is an LTA type molecular sieve membrane, and the operating pressure is 1.0 MPa. NMP is used as the absorption solvent in the absorption process. All other steps and process parameters are consistent with those in Example 2.

[0036] After processing, the final electronic-grade acetylene obtained reaches a purity of 99.999990%, with the contents of hydrogen, oxygen, argon, nitrogen, methane, ethane, ethylene, and propylene all below 0.1 ppb, carbon dioxide at 75 ppb, and propane at 27 ppb.

[0037] Although embodiments of the 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 invention, the scope of which is defined by the appended claims and their equivalents.

[0038] 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. An electronic-grade acetylene purification system based on a dual-membrane method, characterized in that, The system includes a small molecule separation membrane module, a large molecule separation membrane module, an absorption tower, and a desorption tower connected according to the material flow direction. The permeate side of the small molecule separation membrane module is connected to the feed side of the large molecule separation membrane module, and the permeate side of the large molecule separation membrane module is connected to the feed side of the absorption tower. The membrane in the small molecule separation membrane module is a molecular sieve membrane, selected from one or more of the STT, DDR, and CHA types. The membrane in the large molecule separation membrane module is a molecular sieve membrane, selected from one or more of the MFI, LTA, and T types.

2. The purification system according to claim 1, characterized in that, The membrane types in the small molecule separation membrane module and the macromolecule separation membrane module are one or more of the following: flat sheet membrane, tubular membrane, multichannel membrane, or hollow fiber membrane.

3. The purification system according to claim 1, characterized in that, The solvent in the absorption tower is one of liquid ammonia, dimethylformamide, N-methylpyrrolidone, methanol, liquid ammonia, and acetone.

4. The purification system according to claim 1, characterized in that, A first compressor is also provided upstream of the small molecule separation membrane module, and a second compressor is provided between the macromolecule separation membrane module and the absorption tower.

5. The purification system according to claim 1, characterized in that, The middle section of the absorption tower is connected to the top of the absorption tower via a first hydraulic pump and a first heat exchanger.

6. The purification system according to claim 1, characterized in that, The bottom of the absorption tower is connected to the desorption tower via a second hydraulic pump and a second heat exchanger. The bottom of the desorption tower is connected to the top of the absorption tower via a second heat exchanger, a third hydraulic pump, and a third heat exchanger.

7. The purification system according to claim 1, characterized in that, A reboiler is connected to the bottom of the stripping column.

8. The purification system according to claim 1, characterized in that, The top of the analytical tower is connected to the gas-liquid separator via a fourth heat exchanger. The top of the gas-liquid separator is equipped with an acetylene-rich gas outlet, and the bottom of the gas-liquid separator is connected to the analytical tower via a fourth hydraulic pump.

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