Silane impurity removal system for removing impurities from crude silane gas containing impurity ammonia

Abstract

The utility model relates to the technical field of silane impurity removal, and provides a silane impurity removal system for removing impurities from crude silane gas containing impurity ammonia, which is used for purifying the crude silane gas containing the impurity ammonia, so that the operation cycle of the system is favorably improved, and the blocking risk is reduced. The system comprises a rectifying tower, a rectifying condenser, a rectifying condensing tank and a solidification separator, the rectifying tower is connected with the crude product gas conveying pipeline, so that ammonia in the silane crude product gas is rectified and separated, and rectified silane gas is obtained; an inlet of the rectification condenser is connected with the tower top gas outlet of the rectification tower through a pipeline; an inlet of the rectification condensation tank is connected with an outlet of the rectification condenser through a pipeline so as to perform condensation treatment on the silane gas treated by the rectification condenser and obtain ammonia condensate and a silane-containing gas phase; and the solidification separator is used for continuously carrying out condensation treatment on the silane-containing gas phase output from the rectification condensation tank to obtain liquid silane and ammonia crystal substances.

Description

Technical Field

[0001] The utility model relates to the technical field of silane impurity removal, in particular to a silane impurity removal system for removing impurities from crude silane gas containing ammonia as an impurity. Background Art

[0002] Silane products are widely used in the production processes of photovoltaics, panels, and semiconductors. The silane products used in the semiconductor field are electronic grade, so there are strict requirements on the impurity content in silane.

[0003] A common method for producing silane gases is the silicon-magnesium process. This method produces silane and disilane gases containing significant amounts of ammonia. Conventional condensation-liquefaction separation methods, such as distillation and rectification, often cause equipment blockages during the purification of low-ammonia silane gases due to ammonia solidification caused by excessively low temperatures. To avoid frequent equipment blockages, the separation temperature must be increased, but this typically only reduces the ammonia content in the silane gas to ~1.0% and is unable to completely remove it.

[0004] In existing applications, a common method is to further remove trace amounts of ammonia remaining in silane after distillation through a pressure swing adsorption process, leveraging the selective adsorption properties of porous adsorption materials at low temperatures. However, this adsorption process is a batch process, requiring high energy consumption and equipment costs for regeneration. Reducing the ammonia content in the distillation process can significantly extend the regeneration cycle of the ammonia adsorption equipment, thereby improving efficiency and reducing costs. Utility Model Content

[0005] In response to at least one shortcoming in the prior art, the present invention provides a silane impurity removal system for removing impurities from crude silane gas containing ammonia as an impurity. The silane impurity removal system of the present invention is used to purify crude silane gas containing ammonia as an impurity, which is beneficial to improving the system operation cycle and reducing the risk of blockage.

[0006] In order to achieve its purpose, the present invention provides the following technical solutions:

[0007] The utility model provides a silane impurity removal system for removing impurities from crude silane gas containing ammonia as an impurity. The system comprises a distillation tower, a distillation condenser, a distillation condensation tank and a solidification separator.

[0008] The distillation tower is connected to a crude gas delivery pipeline for delivering crude silane gas to perform distillation and separation on impurities in the crude silane gas and obtain rectified silane gas; the distillation tower is provided with a tower top gas outlet for outputting the rectified silane gas;

[0009] The inlet of the rectification condenser is connected to the top gas outlet of the rectification tower through a pipeline;

[0010] The inlet of the rectification condensation tank is connected to the outlet of the rectification condenser through a pipeline to condense the silane gas after being treated by the rectification condenser and obtain an ammonia-containing condensate and a silane-containing gas phase;

[0011] The solidification separator is used to continue condensing the silane-containing gas phase output from the distillation condensation tank to obtain crystals of liquid silane and ammonia; the solidification separator includes a tank body and a silane gas inlet, a nitrogen inlet and an outlet arranged on the tank body, the silane gas inlet is connected to the gas outlet of the distillation condensation tank through a pipeline, and the nitrogen inlet is connected to a nitrogen inlet pipe for introducing nitrogen into the liquid silane condensed in the solidification separator; a first filter for filtering the liquid silane in the solidification separator is provided in the inner cavity of the tank body, and a liquid phase outlet is provided on the tank body for outputting the liquid silane filtered by the first filter to the outside.

[0012] Preferably, the tank body of the solidification separator is provided with a partition for dividing the inner cavity of the tank body into an air inlet area and an air outlet area, the silane gas inlet and the nitrogen gas inlet are provided on the wall surface of the tank body corresponding to the air inlet area, and the air outlet is provided on the wall surface of the tank body corresponding to the air outlet area;

[0013] The lower parts of the air inlet area and the air outlet area are communicated with each other.

[0014] Preferably, in the gas outlet area, along the gas flow direction of the gas outlet, a defoaming net and a second filter are sequentially provided at the bottom of the gas outlet.

[0015] Preferably, the pore size of the defoaming net is no greater than 5 μm, and the filtration pore sizes of the second filter and the first filter are no greater than 0.01 μm respectively.

[0016] Preferably, the system further comprises a cryogenic condenser;

[0017] The gas inlet of the cryogenic condenser is connected to the gas outlet of the solidification separator through a pipeline to condense the gas output from the solidification separator and obtain non-condensable gas and liquid phase;

[0018] The cryogenic condenser is provided with a non-condensable gas outlet for outputting the non-condensable gas and a liquid outlet for outputting the liquid phase obtained in the cryogenic condenser;

[0019] The non-condensable gas outlet is connected to the nitrogen gas inlet pipe through a non-condensable gas output pipeline.

[0020] Furthermore, a compressor is provided on the nitrogen inlet pipe.

[0021] Furthermore, the liquid outlet of the cryogenic condenser is connected to the solidification separator through a pipeline.

[0022] Preferably, the first filter is a filter plate;

[0023] The bottom of the solidification separator is provided with a crystallized precipitate outlet, and the filter plate is arranged obliquely in the inner cavity of the tank body, and is arranged so that the crystallized precipitate trapped on the filter plate tends to flow toward the area at the bottom of the solidification separator where the crystallized precipitate outlet is provided;

[0024] The crystallized precipitate outlet is communicated with the rectification condenser through a crystallized precipitate output pipeline, and a valve is provided on the crystallized precipitate output pipeline.

[0025] Preferably, the liquid phase outlet of the tank body is connected to a product output pipeline, and a liquid filter and a valve are provided on the product output pipeline.

[0026] Furthermore, a reboiler is provided at the bottom of the distillation tower;

[0027] The distillation condensation tank is provided with a condensate outlet, and the condensate outlet is connected to the upper part of the distillation tower through a pipeline.

[0028] The technical solution provided by the utility model has the following beneficial effects:

[0029] The silane impurity removal system of the utility model is used to purify the crude silane gas containing the impurity ammonia, which can reduce the risk of blockage and help improve the system operation cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a silane impurity removal system in accordance with one embodiment. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with the embodiments. It should be understood that the following embodiments are only for a better understanding of the present invention and do not mean that the present invention is limited to the following embodiments.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0033] Directional terms such as "upper," "lower," "top," and "bottom" mentioned or potentially mentioned in this specification are defined relative to the configurations shown in the accompanying drawings. These terms are relative and may vary depending on the location and usage of the component. The words "inner" and "outer" refer to directions toward and away from the geometric center of a particular component, respectively. Furthermore, the terms "first," "second," and so on are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] See also Figure 1 The utility model provides a silane impurity removal system for removing impurities from crude silane gas containing ammonia as an impurity. The system mainly includes a distillation tower T101, a distillation condenser E101, a distillation condensation tank V101 and a solidification separator V102.

[0035] Among them, the distillation tower T101 is used to distill and separate impurities such as ammonia in the crude silane gas and obtain distilled silane gas. The distillation tower T101 is connected to the crude gas delivery pipeline 17 for conveying the crude silane gas. The crude silane gas containing impurities such as ammonia is distilled and separated by the distillation tower T101 to obtain distilled silane gas; the distillation tower T101 is provided with a top gas outlet for outputting the distilled silane gas obtained in the distillation tower T101.

[0036] The inlet of the distillation condenser E101 and the top gas outlet of the distillation tower T101 are connected by a pipeline, and are used to receive the distilled silane gas obtained in the distillation tower T101 and further condense and cool it.

[0037] The outlet of the distillation condenser E101 and the inlet of the distillation condenser V101 are connected by a pipeline. The distillation condenser V101 is used to further condense and cool the silane gas condensed in the distillation condenser E101, and liquefy ammonia by condensation to obtain ammonia-containing condensate and a silane-containing gas phase.

[0038] The solidification separator V102 is used to further condense the silane-containing gas phase output from the distillation condenser V101, thereby liquefying the silane to obtain liquid silane. A small amount of ammonia entrained therein is condensed and crystallized to produce ammonia crystals. The solidification separator V102 comprises a tank body 16, which is provided with a silane gas inlet, a nitrogen gas inlet, and a gas outlet. The silane gas inlet of the solidification separator V102 is connected to the gas outlet of the distillation condenser V101 via pipeline 9. The silane gas condensed in the distillation condenser V101 enters the solidification separator V102 for further condensation and cooling, resulting in a liquid phase primarily consisting of silane. The nitrogen inlet is connected to a nitrogen inlet pipe 8 for introducing nitrogen into the liquid silane condensed in the solidification separator V102. During the condensation process in the solidification separator V102, nitrogen is introduced into the condensed liquid silane through the nitrogen inlet pipe 8. Specifically, the nitrogen inlet pipe 8 extends, for example, into the lower portion of the inner cavity of the solidification separator V102 so that it can contact or be immersed in the liquid phase condensed in the solidification separator V102. The nitrogen inlet pipe 8 can also be connected to a nitrogen gas source via a pipeline. A nitrogen valve 5 is provided on the pipeline, and the nitrogen valve 5 is opened as needed to replenish nitrogen.

[0039] A first filter 3 is installed within the interior of tank 16, filtering the liquid silane condensed in coagulation separator V102. Tank 16 also has a liquid outlet for discharging the filtered liquid silane from first filter 3 to produce purified silane. Furthermore, the liquid outlet of tank 16 is connected to product output pipeline 11, which is also equipped with a liquid filter 4 and a valve 7.

[0040] During the condensation process in solidification separator V102, the silane gas is condensed and liquefied. The introduction of nitrogen into the liquid phase during this condensation process can reduce the size of the entrained trace ammonia as it condenses into ice crystals, forming micro-ice crystals and reducing the risk of equipment blockage. The introduction of nitrogen into the liquid phase provides a large number of microbubbles as condensation nuclei for the trace ammonia in the liquid. In the liquid silane environment, the trace ammonia gas forms micro-ice crystals under the action of the condensation nuclei and settles to the bottom. The nitrogen introduced into solidification separator V102 also prevents ice crystals from depositing on the tube walls and container sidewalls, reducing the risk of blockage.

[0041] Preferably, if Figure 1 As shown, a partition 14 is provided within the tank body 16 of the solidification separator V102. This partition 14 divides the inner cavity of the tank body 16 into an air inlet region 12 and an air outlet region 13. The lower portions of the air inlet region 12 and the air outlet region 13 are interconnected. The silane gas inlet and nitrogen gas inlet of the solidification separator V102 are both located on the wall of the tank body 16 corresponding to the position of the air inlet region 12. The air outlet of the solidification separator V102 is located on the wall of the tank body 16 corresponding to the position of the air outlet region 13.

[0042] Preferably, in the outlet region 13, along the gas flow direction of the outlet of the solidification separator V102, a defoaming net 1 and a second filter 2 are sequentially arranged at the bottom of the outlet. Preferably, the pore size of the defoaming net 1 is no greater than 5 μm, and the filtration pore sizes of the second filter 2 and the first filter 3 are each no greater than 0.01 μm. The filters are made of, for example, sintered ceramic. Uncondensed gas within the solidification separator V102 is defoamed by the defoaming net 1 and filtered by the second filter 2 in the outlet region 13 before being discharged downstream through the outlet.

[0043] Preferably, the first filter 3 is a filter plate, and the bottom of the solidification separator V102 is provided with a crystallized precipitate outlet. The filter plate is arranged obliquely at the lower part of the inner cavity of the tank body 16 and is located above the liquid phase outlet, such as Figure 1 As shown, when tilted, the filter plates are arranged so that the crystallized precipitate trapped on them tends to flow toward the bottom of the solidification separator V102, where a crystallization outlet is located. This outlet is connected to the distillation condenser V101 via a crystallization outlet pipeline 10, which is equipped with a valve 6. Crystallized precipitates, such as ammonia crystals, can be conveniently discharged into the distillation condenser V101 for heating and liquefaction, depending on cleaning needs.

[0044] Preferably, the system of the present invention also includes a cryogenic condenser E102, which is used to further condense and separate the uncondensed gas in the solidification separator V102 to obtain non-condensable gas and a liquid phase. The gas inlet of the cryogenic condenser E102 is connected to the gas outlet of the solidification separator V102 via a pipeline. The cryogenic condenser E102 also has a non-condensable gas outlet for outputting non-condensable gas and a liquid outlet for outputting the liquid phase obtained in the cryogenic condenser E102. The non-condensable gas outlet is connected to the nitrogen inlet pipe 8 via a non-condensable gas output pipeline 15. The non-condensable gas is primarily nitrogen. This arrangement allows the nitrogen to be recycled within the system. The nitrogen inlet pipe 8 is equipped with a compressor C101, such as a diaphragm compressor, for pressurizing the gas transported by the nitrogen inlet pipe 8. The liquid outlet of the cryogenic condenser E102 is connected to the solidification separator V102 through a pipeline, so that the condensed liquid phase is refluxed into the solidification separator V102.

[0045] More specifically, a reboiler E103 is provided at the bottom of the distillation tower T101. The packing in the distillation tower T101 can be conventional packing in the art, including but not limited to metal perforated plate packing, porous ceramic material, metal mesh packing, etc.

[0046] The silane impurity removal system of the present invention is used to purify crude silane gas containing impure ammonia. The crude silane gas is first distilled and separated by a distillation tower T101 to remove constant-level ammonia. Then, the silane gas containing trace ammonia is condensed multiple times in sequence through a distillation condenser E101, a distillation condensation tank V101, and a solidification separator V102. During the condensation process in the solidification separator V102, nitrogen is introduced into the liquid phase to facilitate the formation of smaller micro-ice crystals. Purification of crude silane gas containing impurity ammonia by this system can reduce the risk of equipment blockage during impurity removal and extend the operating cycle of the process system.

[0047] In the silane impurity removal system of the present invention, the devices or components such as the distillation tower, distillation condenser, distillation condensation tank, and reboiler used can all be conventional devices or components with corresponding functions in the art, and no further description is given.

[0048] When the silane impurity removal system of the present invention is used to purify crude silane gas, those skilled in the art can adopt the appropriate process conditions required according to the purification requirements. Figure 1 When the silane impurity removal system shown is used to purify crude silane gas containing ammonia impurities, for example, the following process conditions can be adopted: the pressure of the distillation tower T101 is 0.12-2Mpa, and the top temperature is ≤-10°C, for example, -10°C to -75°C; the bottom temperature is ≥10°C, for example, 10-35°C; the temperature of the distillation condenser E101 is -20 to -50°C; the temperature of the distillation condenser V101 is -40°C to -90°C and the pressure is 0.13-1.9Mpa; the temperature of the solidification separator V102 is -80°C to -160°C, and the pressure is 0.14-1.85Mpa; the temperature of the cryogenic condenser E102 is, for example, 10-20°C lower than the temperature of the solidification separator V102.

[0049] The silane impurity removal system of the present invention can be used for the impurity removal treatment of various crude silane gases, such as one or more of monosilane, disilane, and trisilane; the impurities contained therein include, in addition to ammonia, hydrogen sulfide, etc.

[0050] The following examples illustrate the application of the silane impurity removal system of the present invention in the impurity removal treatment of crude silane gas.

[0051] Example 1

[0052] Example Figure 1 The silane impurity removal system shown is used to purify crude silane gas containing ammonia. Figure 1The system shown includes a distillation tower T101, a distillation condenser E101, a distillation condenser tank V101, a solidification separator V102, and a cryogenic condenser E102. A reboiler E103 is located at the bottom of distillation tower T101. Crude silane gas containing ammonia (20% ammonia by volume) is first passed into distillation tower T101 for rectification. The pressure of distillation tower T101 is 0.6 MPa, the top temperature is -40°C, and the bottom temperature is 25°C. The packing in distillation tower T101 is Raschig ring metal packing. Silane gas output from the top of distillation tower T101 first flows through distillation condenser E101 at a temperature of -43°C before entering distillation condenser tank V101 for condensation at a temperature of -58°C and a pressure of 0.55 MPa. At least a portion of the condensed liquid phase is refluxed back into distillation tower T101 at a reflux ratio of 5. The silane gas treated in the distillation condenser V101 enters the gas inlet area 12 from the silane gas inlet of the solidification separator V102 to continue condensing. The temperature of the solidification separator is -80°C and the pressure is 0.5 MPa. During the condensation process, pressurized nitrogen is introduced into the condensed liquid phase through the nitrogen inlet pipe 8 (the nitrogen temperature is -90°C and the nitrogen flow rate is 5% of the silane gas flow rate entering the solidification separator (the flow rate unit is m 3 / h)); the remaining gas that has not condensed is defoamed by the defoaming net 1 and filtered by the second filter 2 in the gas outlet area 13, and then enters the cryogenic condenser E102. The temperature of the cryogenic condenser E102 is 15°C lower than that of the solidification separator; the non-condensable gas in the cryogenic condenser E102 is introduced into the nitrogen inlet pipe 8 through the non-condensable gas output pipeline 15, and is pressurized by the compressor C101 and circulated to the solidification separator V102. The liquid phase in the cryogenic condenser E102 refluxes into the solidification separator V102. After the liquid phase in the solidification separator V102 is filtered by the first filter 3 to intercept the crystalline precipitate, it enters the product output pipeline 11 through the liquid phase outlet, and is filtered by the liquid filter 4 and extracted as purified silane. The pore size of the defoaming net 1 is 5μm, and the filtration pore sizes of the second filter 2 and the first filter 3 are 0.01μm respectively. About Figure 1 For any parts of the system not otherwise explained, please refer to the previous description and no further details will be given.

[0053] Purified monosilane extracted from product output pipeline 11 was heated to a gaseous state and then tested for ammonia content, which was found to be <0.01% by volume. The system operated for a total of 2,160 hours, with no blockages requiring cleaning or maintenance.

[0054] Comparative Example 1

[0055] Compared with the above Example 1, the main difference is that the silane impurity removal system used is Figure 1In contrast, no nitrogen inlet and nitrogen inlet pipe are provided on the solidification separator. Therefore, in the purification process of crude monosilane gas, no nitrogen is introduced into the solidification separator in this comparative example.

[0056] The purified monosilane was finally produced and heated to a gaseous state to detect the ammonia content, which was found to be 8% by volume. After the system had been running for a total of 480 hours, it was necessary to clean the blockage and conduct maintenance.

[0057] It will be readily understood that the above embodiments are merely examples for clarity of description and are not intended to limit the present invention to these embodiments. Persons skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A silane impurity removal system for removing impurities from crude silane gas containing ammonia impurities, characterized in that: The system includes a distillation tower, a distillation condenser, a distillation condensation tank and a solidification separator; The distillation tower is connected to a crude gas delivery pipeline for delivering crude silane gas to perform distillation and separation on impurities in the crude silane gas and obtain rectified silane gas; the distillation tower is provided with a tower top gas outlet for outputting the rectified silane gas; The inlet of the rectification condenser is connected to the top gas outlet of the rectification tower through a pipeline; The inlet of the rectification condensation tank is connected to the outlet of the rectification condenser through a pipeline to condense the silane gas after being treated by the rectification condenser and obtain an ammonia-containing condensate and a silane-containing gas phase; The solidification separator is used to continue condensing the silane-containing gas phase output from the distillation condensation tank to obtain crystals of liquid silane and ammonia; the solidification separator includes a tank body and a silane gas inlet, a nitrogen inlet and an air outlet arranged on the tank body, the silane gas inlet is connected to the gas outlet of the distillation condensation tank by a pipeline, and the nitrogen inlet is connected to a nitrogen inlet pipe for introducing nitrogen into the liquid silane condensed in the solidification separator; a first filter for filtering the liquid silane in the solidification separator is provided in the inner cavity of the tank body, and a liquid phase outlet for outputting the liquid silane filtered by the first filter is provided on the tank body; along the gas flow direction of the air outlet, a defoaming net and a second filter are provided at the bottom of the air outlet in sequence; a compressor is provided on the nitrogen inlet pipe; the first filter is arranged obliquely in the inner cavity of the tank body.

2. The silane impurity removal system according to claim 1, characterized in that: The tank body of the solidification separator is provided with a partition for dividing the inner cavity of the tank body into an air inlet area and an air outlet area, the silane gas inlet and the nitrogen gas inlet are provided on the wall surface of the tank body corresponding to the air inlet area, and the air outlet is provided on the wall surface of the tank body corresponding to the air outlet area; The lower parts of the air inlet area and the air outlet area are communicated with each other.

3. The silane impurity removal system according to claim 2, characterized in that: In the gas outlet area, a defoaming net and a second filter are sequentially provided at the bottom of the gas outlet along the gas flow direction of the gas outlet.

4. The silane impurity removal system according to claim 3, characterized in that: The pore size of the defoaming net is no greater than 5 μm, and the filtration pore sizes of the second filter and the first filter are no greater than 0.01 μm respectively.

5. The silane impurity removal system according to any one of claims 1 to 4, characterized in that: The system also includes a cryogenic condenser; The gas inlet of the cryogenic condenser is connected to the gas outlet of the solidification separator through a pipeline to condense the gas output from the solidification separator and obtain non-condensable gas and liquid phase; The cryogenic condenser is provided with a non-condensable gas outlet for outputting the non-condensable gas and a liquid outlet for outputting the liquid phase obtained in the cryogenic condenser; The non-condensable gas outlet is connected to the nitrogen gas inlet pipe through a non-condensable gas output pipeline.

6. The silane impurity removal system according to claim 5, characterized in that: The liquid outlet of the cryogenic condenser is connected to the solidification separator through a pipeline.

7. The silane impurity removal system according to any one of claims 1 to 4, characterized in that: The first filter is a filter plate; The bottom of the solidification separator is provided with a crystallized precipitate outlet, and the filter plate is arranged obliquely in the inner cavity of the tank body, and is arranged so that the crystallized precipitate trapped on the filter plate tends to flow toward the area at the bottom of the solidification separator where the crystallized precipitate outlet is provided; The crystallized precipitate outlet is communicated with the rectification condenser through a crystallized precipitate output pipeline, and a valve is provided on the crystallized precipitate output pipeline.

8. The silane impurity removal system according to any one of claims 1 to 4, characterized in that: The liquid phase outlet of the tank body is connected to a product output pipeline, and a liquid filter and a valve are provided on the product output pipeline.

9. The silane impurity removal system according to any one of claims 1 to 4, characterized in that: The bottom of the distillation tower is provided with a reboiler; The distillation condensation tank is provided with a condensate outlet, and the condensate outlet is connected to the upper part of the distillation tower through a pipeline.

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