Polycrystalline silicon production waste gas treatment system
By adopting the combination technology of membrane separation unit and adsorption unit in the polycrystalline silicon production waste gas treatment system, the problems of high operating costs of the waste gas treatment system, exceeding the standard of combustible materials and floating out of hydrolysate are solved, and zero emissions of waste gas and reduced operating costs are achieved.
Patent Information
- Application Number
- CN202421620660.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-10
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2034-07-10
AI Technical Summary
The existing polycrystalline silicon production waste gas treatment system has high operating costs, and the combustible substances exceed the standard and hydrolysates float out of the system when the waste gas is exhausted affecting the external environment.
The exhaust gas treatment system is adopted that combines a membrane separation unit and an adsorption unit. The exhaust gas is initially separated into hydrogen and nitrogen through the membrane separation unit, and then circulated through two adsorption units until all are purified to achieve zero exhaust emissions.
It achieves zero emissions of waste gas, reduces the operating costs of the polysilicon industry, and avoids the problems of excessive combustible materials and hydrolysate floating out when exhaust gas is discharged.
Smart Images
Figure CN222943223U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of polysilicon production, in particular to a polysilicon production waste gas treatment system. Background Art
[0002] At present, the current status of waste gas treatment in the polysilicon industry is that the waste gas of the whole plant is centrally treated. The waste gas contains a large amount of nitrogen, hydrogen and a small amount of chlorosilane. After the waste gas is compressed and condensed to recover the chlorosilane in the waste gas, the remaining gas is all hydrolyzed through the leaching tower, and the non-condensing steam is discharged into the air. There are still the following shortcomings in the above waste gas treatment process: 1. The waste gas contains a large amount of nitrogen and hydrogen. After this part of the waste gas is vented, the system will lack hydrogen and nitrogen, so it is necessary to build a new hydrogen production device and air separation nitrogen production device, which greatly increases the operating cost of polysilicon; 2. When the waste gas is vented, the vent pipeline will catch fire due to excessive combustibles in the system (hydrogen, dichlorosilane, etc.); 3. When the waste gas is vented, the hydrolyzate (silicon dioxide) mixed in the waste gas will cause the hydrolyzate to float out of the outside world, thereby affecting the external environment. Summary of the invention
[0003] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the utility model is to provide a polysilicon production waste gas treatment system, which solves the technical problems of high operating cost of the existing polysilicon production waste gas treatment system, excessive combustible matter in the system when the waste gas is discharged, and hydrolyzate floating out and affecting the external environment.
[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:
[0005] A polysilicon production waste gas treatment system includes: a membrane separation unit, the input end of which is connected to an air intake pipe; a first adsorption unit, the inlet of which is connected to the post-membrane gas outlet of the membrane separation unit; a second adsorption unit, the inlet of which is connected to the pre-membrane gas outlet of the membrane separation unit; the desorption gas outlet of the first adsorption unit is connected to the inlet of the second adsorption unit; the desorption gas outlet of the second adsorption unit is connected to the membrane separation unit. The desorption gas separated by the first adsorption unit is mixed with the pre-membrane gas separated by the membrane separation unit and then enters the second adsorption unit, and the desorption gas separated by the second adsorption unit flows back to the membrane separation unit.
[0006] The utility model simultaneously applies a membrane separation unit and an adsorption unit to the waste gas treatment system, and circulates the waste gas through two sets of separation devices until it is completely purified, thereby achieving zero waste gas emission, completely solving the waste gas emission problem of waste gas elution, and greatly reducing the operating cost of the polysilicon industry.
[0007] Optionally, the membrane separation unit is used to separate the waste gas and obtain post-membrane gas and pre-membrane gas; the first adsorption unit is used to separate the post-membrane gas and obtain product hydrogen and a first desorption gas; the second adsorption unit is used to separate the mixed pre-membrane gas and the first desorption gas and obtain product hydrogen and a second desorption gas, and the second desorption gas flows back to the membrane separation unit.
[0008] Optionally, the output end of the membrane separation unit is connected to the input ends of the first adsorption unit and the second adsorption unit through the first pipeline and the second pipeline respectively; the first adsorption unit is connected with a first product pipeline and a first desorption gas pipeline; one end of the first desorption gas pipeline is connected to the output end of the first adsorption unit, and the other end is connected to the second pipeline; the second adsorption unit is connected with a second product pipeline and a second desorption gas pipeline; one end of the second desorption gas pipeline is connected to the output end of the second adsorption unit, and the other end is connected to the air intake pipeline.
[0009] Optionally, the first adsorption unit and / or the second adsorption unit is a pressure swing adsorption unit.
[0010] Optionally, the first adsorption unit uses a PSA hydrogen purification pressure swing adsorption column.
[0011] Optionally, the second adsorption unit uses a PSA nitrogen purification pressure swing adsorption column.
[0012] Optionally, the system further comprises a pretreatment unit, the output end of the pretreatment unit is connected to the input end of the membrane separation unit via the air inlet pipe, the pretreatment unit purifies the recovered exhaust gas and sends the purified hydrogen-nitrogen mixed gas into the membrane separation unit.
[0013] Optionally, the pretreatment unit includes an alkali washing tower and a filter, the filter input end is connected to the output end of the alkali washing tower, and the filter output end is connected to the input end of the membrane separation unit;
[0014] Optionally, the pretreatment unit includes a caustic washing tower and a filter, the input end of the caustic washing tower is connected to the output end of the filter, and the output end of the caustic washing tower is connected to the input end of the membrane separation unit.
[0015] The pretreatment unit comprises an alkali washing tower and a filter, and the pretreatment unit comprises a water washing tower, wherein the output end of the water washing tower is connected to the input end of the membrane separation unit.
[0016] Compared with the prior art, the beneficial effects of the utility model are:
[0017] The utility model simultaneously applies a membrane separation unit and an adsorption unit to the waste gas treatment system, and circulates the waste gas through two sets of separation devices until it is completely purified, thereby achieving zero waste gas emission, completely solving the waste gas emission problem of waste gas elution, and greatly reducing the operating cost of the polysilicon industry. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0019] Figure 1 It is a structural schematic diagram of the utility model.
[0020] Figure numerals: 1, pretreatment unit; 11, air inlet pipeline; 2, membrane separation unit; 21, first pipeline; 22, second pipeline; 3, first adsorption unit; 31, first product pipeline; 32, first desorption gas pipeline; 4, second adsorption unit; 41, second product pipeline; 42, second desorption gas pipeline. DETAILED DESCRIPTION
[0021] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.
[0022] In the description of the embodiments of the present utility model application, it needs to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", "end", "side", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present utility model application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present utility model application.
[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present utility model application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.
[0024] In the embodiments of the present utility model application, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present utility model application can be understood according to the specific circumstances.
[0025] In the embodiments of the utility model application, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.
[0026] The disclosure below provides many different embodiments or examples for realizing different structures of the embodiments of the utility model application. In order to simplify the disclosure of the embodiments of the utility model application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the utility model application. In addition, the embodiments of the utility model application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.
[0027] The embodiments of the present utility model are described in detail below with reference to the accompanying drawings.
[0028] The current status of waste gas treatment in the polysilicon industry: the waste gas of the whole plant is centrally treated. The waste gas contains a large amount of nitrogen, hydrogen and a small amount of chlorosilane. After the waste gas is compressed and condensed to recover the chlorosilane in the waste gas, the remaining gas is all hydrolyzed through the leaching tower, and the non-condensing steam is discharged into the air. There are still the following shortcomings in the above waste gas treatment process: 1. The waste gas contains a large amount of nitrogen and hydrogen. After this part of the waste gas is vented, the system will lack hydrogen and nitrogen, so it is necessary to build a new hydrogen production device and air separation nitrogen production device, which greatly increases the operating cost of polysilicon; 2. When the waste gas is vented, the vent pipeline will catch fire due to excessive combustibles in the system (hydrogen, dichlorosilane, etc.); 3. When the waste gas is vented, the hydrolyzate (silicon dioxide) mixed in the waste gas will cause the hydrolyzate to float out of the outside world, thereby affecting the external environment.
[0029] like Figure 1 As shown, the embodiment of the utility model application provides a polysilicon production waste gas treatment system to solve the above problems. The system includes: a membrane separation unit 2, a first adsorption unit 3 and a second adsorption unit 4.
[0030] The inlet of the first adsorption unit 3 is connected to the outlet of the post-membrane gas of the membrane separation unit 2; the inlet of the second adsorption unit 4 is connected to the outlet of the pre-membrane gas of the membrane separation unit 2; the outlet of the first adsorption unit 3 is connected to the inlet of the second adsorption unit 4, and the outlet of the second adsorption unit 4 is connected to the membrane separation unit 2. The purified hydrogen-nitrogen mixed gas is sent to the membrane separation unit 2, and the membrane separation unit 2 is used to separate the purified hydrogen-nitrogen mixed gas and obtain the post-membrane gas (main component hydrogen) and the pre-membrane gas (main component nitrogen). The post-membrane gas separated by the membrane separation unit 2 is sent to the first adsorption unit 3, and the first adsorption unit 3 adsorbs and separates the post-membrane gas to obtain the first decomposition gas (containing more nitrogen) and the product hydrogen. The pre-membrane gas separated by the membrane separation unit 2 is mixed with the first decomposition gas and sent to the second adsorption unit 4. The second adsorption unit 4 separates the mixed pre-membrane gas and the first decomposition gas to obtain the second decomposition gas (containing more hydrogen) and the product hydrogen, and the second decomposition gas flows back to the membrane separation unit 2. Through continuous circulation and separation, the complete separation of the hydrogen and nitrogen mixture is finally achieved.
[0031] Specifically, the membrane separation unit 2 can effectively perform preliminary separation of hydrogen and nitrogen, that is, obtain post-membrane gas mainly containing high-purity hydrogen and part of nitrogen, and pre-membrane gas rich in relatively high-purity nitrogen and part of hydrogen. The input end of the first adsorption unit 3 is connected to the output end of the membrane separation unit 2, and the membrane separation unit 2 introduces the post-membrane gas into the first adsorption unit 3. The post-membrane gas is separated by the first adsorption unit 3 to obtain purified product hydrogen and the first analytical gas (a mixed gas rich in relatively high-purity nitrogen and part of hydrogen), and the first analytical gas and the pre-membrane gas are mixed and then enter the second adsorption unit 4. The second adsorption unit 4 is connected to the membrane separation unit 2, and the second adsorption unit 4 separates the mixed pre-membrane gas and the first analytical gas to obtain the second analytical gas (a mixed gas rich in relatively high-purity hydrogen and part of nitrogen) and purified product hydrogen, and the second analytical gas is circulated and introduced into the membrane separation unit 2.
[0032] More specifically, the output end of the membrane separation unit 2 is connected to the input end of the first adsorption unit 3 and the second adsorption unit 4 through the first pipeline 21 and the second pipeline 22 respectively; the first adsorption unit 3 is connected with a first product pipeline 31 and a first desorption gas pipeline 32; one end of the first desorption gas pipeline 32 is connected to the output end of the first adsorption unit 3, and the other end is connected to the second pipeline 22; the desorption gas in the first desorption gas pipeline 32 is mixed with the tail gas in the second pipeline 22 and enters the second adsorption unit 4; the second adsorption unit 4 is connected with a second product pipeline 41 and a second desorption gas pipeline 42; one end of the second desorption gas pipeline 42 is connected to the output end of the second adsorption unit 4, and the other end is connected to the intake pipeline 11, and the desorption gas in the second desorption gas pipeline 42 flows back to the intake pipeline 11 through the second desorption gas pipeline 42 and is mixed with the hydrogen-nitrogen mixed gas in the intake pipeline 11 and then sent to the membrane separation unit 2 for a new round of separation and purification. The hydrogen purified by the first adsorption unit 3 and the second adsorption unit 4 can be connected to the hydrogen user through the first product pipeline 31 and the second product pipeline 41.
[0033] Optionally, the membrane separation unit 2 uses a membrane separator, which uses the difference in the permeation rate of different gases in the membrane material to achieve gas separation. In this process, the permeated gas (gas after the membrane) is mainly high-purity hydrogen and part of nitrogen, while the tail gas (gas before the membrane) is rich in high-purity nitrogen and part of hydrogen.
[0034] Optionally, the first adsorption unit 3 and / or the second adsorption unit 4 is a pressure swing adsorption unit.
[0035] Optionally, the first adsorption unit 3 uses a PSA hydrogen purification pressure swing adsorption column. The PSA technology uses the adsorption capacity of the adsorbent for specific gases to achieve gas separation under pressure changes. In this process, the product gas is hydrogen with a purity of more than 99%, while the analysis gas is a mixed gas rich in higher purity nitrogen and part of hydrogen. The purity of the hydrogen is further improved by the first adsorption unit 3 to meet the standards for industrial applications.
[0036] Optionally, the second adsorption unit 4 uses a PSA nitrogen purification pressure swing adsorption column. In the second adsorption unit 4, the nitrogen is further purified, and the product gas is nitrogen with a purity of more than 99.9%, while the desorption gas is a mixed gas rich in high-purity hydrogen and part of nitrogen. The second adsorption unit 4 not only achieves efficient purification of nitrogen, but also makes full use of the gas in the entire system, thereby improving the efficiency of resource utilization.
[0037] Optionally, the system further includes a pretreatment unit 1, which purifies the recovered waste gas to obtain a hydrogen-nitrogen mixed gas. Specifically, the input end of the membrane separation unit 2 is connected to the output end of the pretreatment unit 1, and more specifically, the output end of the pretreatment unit 1 is connected to the input end of the membrane separation unit 2 through an air intake pipe 11.
[0038] As an implementation scenario, in this scenario, the pretreatment unit 1 includes an alkali washing tower and a filter. Optionally, the output end of the alkali washing tower is connected to the input end of the filter, and the output end of the filter is connected to the input end of the membrane separation unit 2; or the output end of the filter is connected to the input end of the alkali washing tower, and the output end of the alkali washing tower is connected to the input end of the membrane separation unit 2. When in use, first, the waste gas from which chlorosilane has been recovered is introduced into the alkali washing tower and the filter. The alkaline solution in the alkali washing tower can effectively neutralize the acidic substances in the waste gas and remove harmful components such as chlorosilane, while the filter further intercepts solid particles in the waste gas, such as silicon dioxide, to ensure the purity of the waste gas. Through the pretreatment unit 1, the impurities in the waste gas are greatly reduced, laying a solid foundation for subsequent purification work.
[0039] As another implementation scenario, in this scenario, the pretreatment unit 1 includes a water washing tower, and the output end of the water washing tower is connected to the input end of the membrane separation unit 2. When in use, the waste gas of the recovered chlorosilane is purified to obtain a hydrogen-nitrogen mixed gas.
[0040] A polysilicon production waste gas treatment system comprises the following steps:
[0041] Step S1, introduce the waste gas from which chlorosilane has been recovered into the alkali washing tower and the filter. The alkaline solution in the alkali washing tower can effectively neutralize the acidic substances in the waste gas and remove harmful components such as chlorosilane. The filter further intercepts solid particles in the waste gas, such as silicon dioxide, to ensure the purity of the waste gas. After this step, the impurities in the waste gas are greatly reduced, laying a solid foundation for subsequent purification work.
[0042] Step S2, the purified hydrogen-nitrogen mixed gas is sent to a membrane separator. The membrane separator uses the difference in the permeation rate of different gases in the membrane material to achieve gas separation. In this process, the permeated gas is mainly high-purity hydrogen and part of nitrogen, while the tail gas is rich in high-purity nitrogen and part of hydrogen. This step effectively separates hydrogen and nitrogen preliminarily, which facilitates the subsequent purification work.
[0043] Step S3, the permeate gas is introduced into the PSA hydrogen purification pressure swing adsorption column. PSA technology uses the adsorption capacity of the adsorbent for specific gases to achieve gas separation under pressure changes. In this process, the product gas is hydrogen with a purity of more than 99%, while the desorption gas is a mixed gas rich in higher purity nitrogen and part of hydrogen. This step further improves the purity of hydrogen to meet the standards for industrial applications.
[0044] In step S4, the tail gas is mixed with the desorption gas from the hydrogen adsorption column and then enters the PSA nitrogen purification pressure swing adsorption column. Here, the nitrogen is further purified, and the product gas is nitrogen with a purity of more than 99.9%, while the desorption gas is a mixed gas rich in high-purity hydrogen and some nitrogen. This step not only achieves efficient purification of nitrogen, but also makes full use of the gas in the entire system, improving the efficiency of resource utilization.
[0045] In step S5, the decomposed gas from the nitrogen adsorption column enters the membrane separator again for a new round of separation and purification. This step is to ensure that the gas in the system can be fully recycled and improve the efficiency of the entire separation and purification process. Through continuous circulation and separation, the complete separation of the hydrogen and nitrogen mixture is finally achieved, achieving the goal of the project.
[0046] Throughout the process, modern chemical engineering technology and advanced equipment were fully utilized, and through careful design and operation, efficient separation and purification of waste gas was achieved. This not only helps to maximize the utilization of resources, but also provides strong support for the sustainable development of the chlorosilane industry. At the same time, it ensures that valuable components in the waste gas can be efficiently recovered and meet environmental emission standards, making a positive contribution to environmental protection. The system can achieve efficient treatment of waste gas after the recovery of chlorosilane, achieving maximum utilization of resources and maximization of environmental benefits.
[0047] Parts not described in detail in this embodiment are well-known techniques in the art.
[0048] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.
Claims
1. A polysilicon production waste gas treatment system, characterized in that: include: A membrane separation unit, the input end of which is connected to an air inlet pipeline; A first adsorption unit, the inlet of which is connected to the post-membrane gas outlet of the membrane separation unit; A second adsorption unit, the inlet of which is connected to the pre-membrane gas outlet of the membrane separation unit; The desorption gas outlet of the first adsorption unit is connected to the inlet of the second adsorption unit; The analytical gas outlet of the second adsorption unit is communicated with the membrane separation unit.
2. A polysilicon production waste gas treatment system according to claim 1, characterized in that: The membrane separation unit is used to separate the waste gas and obtain post-membrane gas and pre-membrane gas; the first adsorption unit is used to separate the post-membrane gas and obtain product hydrogen and a first desorption gas; the second adsorption unit is used to separate the mixed pre-membrane gas and the first desorption gas and obtain product hydrogen and a second desorption gas, and the second desorption gas flows back to the membrane separation unit.
3. A polysilicon production waste gas treatment system according to claim 1 or 2, characterized in that: The output end of the membrane separation unit is connected to the input ends of the first adsorption unit and the second adsorption unit through the first pipeline and the second pipeline respectively; the first adsorption unit is connected with a first product pipeline and a first desorption gas pipeline; one end of the first desorption gas pipeline is connected to the output end of the first adsorption unit, and the other end is connected to the second pipeline; the second adsorption unit is connected with a second product pipeline and a second desorption gas pipeline; one end of the second desorption gas pipeline is connected to the output end of the second adsorption unit, and the other end is connected to the air intake pipeline.
4. A polysilicon production waste gas treatment system according to claim 1, characterized in that: The first adsorption unit and / or the second adsorption unit is a pressure swing adsorption unit.
5. A polysilicon production waste gas treatment system according to claim 1 or 4, characterized in that: The first adsorption unit uses a PSA hydrogen purification pressure swing adsorption column; and / or, The second adsorption unit adopts a PSA nitrogen purification pressure swing adsorption column.
6. A polysilicon production waste gas treatment system according to claim 1, characterized in that: The system also includes a pretreatment unit, the output end of which is connected to the input end of the membrane separation unit through the air inlet pipeline. The pretreatment unit purifies the recovered waste gas and sends the purified hydrogen-nitrogen mixed gas to the membrane separation unit.
7. A polysilicon production waste gas treatment system according to claim 6, characterized in that: The pretreatment unit comprises an alkali washing tower and a filter, the filter input end is connected to the output end of the alkali washing tower, and the filter output end is connected to the input end of the membrane separation unit; or, The pretreatment unit comprises an alkali washing tower and a filter, the input end of the alkali washing tower is connected to the output end of the filter, and the output end of the alkali washing tower is connected to the input end of the membrane separation unit.
8. A polysilicon production waste gas treatment system according to claim 6, characterized in that: The pretreatment unit comprises a water washing tower, and the output end of the water washing tower is connected to the input end of the membrane separation unit.