Silane gas recovery system for polycrystalline silicon production tail gas
By designing polycrystalline silicon production tail gas recycling system, the problem of failure to recycle the use of acne gas in the polysilicon production process in the production process of polysilicon production, realized the reduction of raw material consumption and the reduction of production costs, while reducing the environmental impact.
Patent Information
- Application Number
- CN202421090366.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2025-01-28
- Estimated Expiration
- 2034-05-20
AI Technical Summary
The reusable silane gas contained in the exhaust gas during the polysilicon production process cannot be effectively recycled, resulting in greater raw material consumption and higher production costs.
Design a polysilicon -producing gas recycling system, including liquefied storage device, heat exchanger, and separation device. Through liquefaction and storage tail gas, the heat exchanger is used for gas treatment. Recycle.
By recycling polysilicon to produce a silicane gas in the tail gas, the consumption of raw materials is reduced, the production cost is reduced, and the impact on the environment is reduced.
Smart Images
Figure CN222411071U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of polysilicon production, and in particular relates to a silane gas recovery system for tail gas in polysilicon production. Background Art
[0002] Polysilicon is the most important basic material for the electronic information industry and the solar photovoltaic power generation industry. The existing polysilicon production process for large-scale industrial production is mainly the silane thermal decomposition method; the silane thermal decomposition method is a process of reducing silicon hydride with hydrogen, decomposing silicon hydride into silane, and then cracking it under high temperature conditions to obtain polysilicon.
[0003] The silane thermal decomposition method has many advantages. For example, the preparation of polysilicon does not require too much process equipment and materials, only hydrogen and silicon hydride; the yield of polysilicon preparation is relatively high, reaching more than 90%, and is relatively stable; the temperature and pressure control in the process of preparing polysilicon is relatively strict, and the operation is relatively safe.
[0004] However, the silane thermal decomposition method also has disadvantages. For example, the raw material consumption in the preparation of polysilicon is large, resulting in relatively high production costs. The production exhaust gas of polysilicon contains reusable silane gas. If the silane gas is recycled, the consumption of raw materials in the preparation of polysilicon will be reduced, thereby reducing production costs. Summary of the invention
[0005] The purpose of the utility model is to overcome the deficiencies in the prior art and provide a silane gas recovery system for polysilicon production tail gas. By setting up a silane gas recovery system, reusable silane in the polysilicon production tail gas can be recovered, reducing the consumption of raw materials when preparing polysilicon, thereby reducing production costs.
[0006] The technical solution provided by the utility model is as follows:
[0007] A silane gas recovery system for polysilicon production tail gas comprises a liquefaction storage device for liquefying and storing the polysilicon production tail gas, a first heat exchanger, a second heat exchanger, and a separation device for purifying and separating the silane gas; the separation device comprises an air inlet and an air outlet; the outlet of the liquefaction storage device is connected to the tube-side inlet of the first heat exchanger, the tube-side outlet of the first heat exchanger is connected to the shell-side inlet of the second heat exchanger, the shell-side outlet of the second heat exchanger is connected to the air inlet of the separation device, the air outlet of the separation device is connected to the tube-side inlet of the second heat exchanger, and the tube-side outlet of the second heat exchanger is connected to the silane gas delivery pipeline.
[0008] Furthermore, the liquefied storage device includes an exhaust gas delivery pipe for transporting polysilicon production exhaust gas, a third heat exchanger, a fourth heat exchanger and a storage tank; the exhaust gas delivery pipe is connected to the tube side inlet of the third heat exchanger, the tube side outlet of the third heat exchanger is connected to the tube side inlet of the fourth heat exchanger, the tube side outlet of the fourth heat exchanger is connected to the inlet of the storage tank, and the outlet of the storage tank is connected to the tube side inlet of the first heat exchanger.
[0009] Furthermore, the shell side inlet of the third heat exchanger is connected to a hydrogen gas source, and the shell side outlet of the third heat exchanger is connected to a hydrogen exhaust pipe.
[0010] Furthermore, the shell side inlet of the fourth heat exchanger is connected to a liquid nitrogen source, and the shell side outlet of the fourth heat exchanger is connected to a nitrogen exhaust pipe.
[0011] Furthermore, the shell side inlet of the first heat exchanger is connected to the condensate, and the shell side outlet of the first heat exchanger is connected to the drain pipe.
[0012] Furthermore, the separation device includes a demethanizer, which includes an air inlet and an air outlet. The air inlet of the demethanizer is connected to the shell side outlet of the second heat exchanger, and the air outlet of the demethanizer is connected to the tube side inlet of the second heat exchanger.
[0013] Furthermore, the separation device also includes a sixth heat exchanger, and the methane removal tower also includes a liquid discharge port and a gas reflux port; the shell side inlet of the sixth heat exchanger is connected to the Freon liquid source, and the shell side outlet of the sixth heat exchanger is connected to the Freon discharge pipe; the tube side inlet of the sixth heat exchanger is connected to the liquid discharge port of the methane removal tower, and the tube side outlet of the sixth heat exchanger is connected to the gas reflux port of the methane removal tower.
[0014] Furthermore, the separation device also includes a fifth heat exchanger, and the demethanization tower also includes a gas exhaust port and a liquid reflux port; the shell side inlet of the fifth heat exchanger is connected to the gas exhaust port of the demethanization tower, and the shell side outlet of the fifth heat exchanger is connected to the liquid reflux port of the demethanization tower; the tube side inlet of the fifth heat exchanger is connected to an ethylene liquid source, and the tube side outlet of the fifth heat exchanger is connected to an ethylene exhaust pipe.
[0015] Furthermore, the fifth heat exchanger also includes a methane emission pipe, and the methane emission pipe is connected to the shell-side flow channel of the fifth heat exchanger.
[0016] Compared with the prior art, the beneficial effects of the utility model are:
[0017] 1. By setting up a liquefied storage device to liquefy and store the tail gas produced by polysilicon, the volume of the tail gas produced by polysilicon can be greatly reduced, making it easier to store; by setting up a first heat exchanger to quickly vaporize the liquefied mixed liquid, sufficient mixed gas can be provided for the purification and separation of the separation device.
[0018] 2. By setting up a separation device and a second heat exchanger, the separation device can purify and separate the mixed gas to obtain silane gas; the low-temperature silane gas separated by the separation device can be introduced into the tube-side flow channel of the second heat exchanger to cool the mixed gas in the shell-side flow channel of the second heat exchanger, thereby reducing the consumption of cooling capacity in the separation device.
[0019] 3. By setting up a silane gas recovery system and recovering the silane gas in the tail gas of polysilicon production, the content of silane gas in the tail gas of polysilicon production is reduced, and the impact of the tail gas of polysilicon production on the environment is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a schematic structural diagram of a silane gas recovery system for tail gas from polysilicon production in Example 1 of the utility model.
[0021] Numbers in the figure: liquefied storage device 1, tail gas delivery pipe 11, third heat exchanger 12, fourth heat exchanger 13, storage tank 14, nitrogen exhaust pipe 15, hydrogen exhaust pipe 16, first heat exchanger 2, drain pipe 21, second heat exchanger 3, separation device 4, demethanization tower 41, fifth heat exchanger 42, sixth heat exchanger 43, methane exhaust pipe 44, ethylene exhaust pipe 45, Freon discharge pipe 46. DETAILED DESCRIPTION
[0022] The utility model is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the utility model, and cannot be used to limit the protection scope of the utility model.
[0023] It should be noted that, in the description of the present invention, the directions or positional relationships indicated by terms such as "front", "rear", "left", "right", "up", "down", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.
[0024] Embodiment 1:
[0025] like Figure 1As shown, this embodiment provides a silane gas recovery system for polysilicon production tail gas, including a liquefaction storage device 1 for liquefying and storing polysilicon production tail gas, a first heat exchanger 2, a second heat exchanger 3, and a separation device 4 for purifying and separating silane gas; the separation device includes an air inlet and an air outlet; the outlet of the liquefaction storage device 1 is connected to the tube side inlet of the first heat exchanger 2, the tube side outlet of the first heat exchanger 2 is connected to the shell side inlet of the second heat exchanger 3, the shell side outlet of the second heat exchanger 3 is connected to the air inlet of the separation device 4, the air outlet of the separation device 4 is connected to the tube side inlet of the second heat exchanger 3, and the tube side outlet of the second heat exchanger 3 is connected to the silane gas delivery pipeline.
[0026] The liquefaction storage device 1 includes an exhaust gas delivery pipe 11 for transporting polysilicon production exhaust gas, a third heat exchanger 12, a fourth heat exchanger 13 and a storage tank 14; the exhaust gas delivery pipe 11 is connected to the tube side inlet of the third heat exchanger 12, the tube side outlet of the third heat exchanger 12 is connected to the tube side inlet of the fourth heat exchanger 13, the tube side outlet of the fourth heat exchanger 13 is connected to the inlet of the storage tank 14, and the outlet of the storage tank 14 is connected to the tube side inlet of the first heat exchanger 2.
[0027] In this embodiment, after the polysilicon production exhaust gas is filtered (the filtered polysilicon production exhaust gas includes silane gas, hydrogen and a trace amount of methane), it is transported to the liquefied storage device 1 through the exhaust gas delivery pipe 11, and first passes through the third heat exchanger 12 to cool it to about -155°C; then passes through the fourth heat exchanger 13 to cool it to about -170°C, and then the liquefied mixed liquid is stored in the storage tank 14; the mixed liquid in the storage tank 14 is transported to the first heat exchanger 2, and the mixed liquid is vaporized by the heat medium of the first heat exchanger 2; then the vaporized mixed gas enters the second heat exchanger 3.
[0028] The shell side inlet of the third heat exchanger 12 is connected to a hydrogen gas source, and the shell side outlet of the third heat exchanger 12 is connected to a hydrogen exhaust pipe 16 .
[0029] In this embodiment, the hydrogen source is transported to the third heat exchanger 12 through the hydrogen transport pipe, and the hydrogen in the third heat exchanger 12 is transported to the granular silicon production system through the hydrogen exhaust pipe 16 to be directly used as a raw material for granular silicon production.
[0030] The shell side inlet of the fourth heat exchanger 13 is connected to a liquid nitrogen source, and the shell side outlet of the fourth heat exchanger 13 is connected to a nitrogen exhaust pipe 15 .
[0031] In this embodiment, the liquid nitrogen source is transported to the fourth heat exchanger 13 through the liquid nitrogen transport pipe, and the nitrogen in the fourth heat exchanger 13 is transported to the nitrogen recovery device through the nitrogen exhaust pipe 15 for recycling.
[0032] The shell side inlet of the first heat exchanger 2 is connected to the condensate, and the shell side outlet of the first heat exchanger 2 is connected to the drain pipe 21. The condensate is high temperature water, which can reach about 100°C. It is the condensate liquefied after being used in the silane gas production system. The condensate is recycled through secondary heat to heat the liquid silane gas.
[0033] In this embodiment, the condensate is transported to the first heat exchanger 2 through the transport pipe, and the condensate in the first heat exchanger 2 is transported to the water recovery device for recycling through the drain pipe 21. By using the condensate as a heat medium to heat and vaporize the mixed liquid, it has the advantages of being easy to obtain and can be recycled.
[0034] In this embodiment, the first heat exchanger 2 is a coiled heat exchanger, which has good heat exchange effect and can achieve more efficient heat exchange for liquid silane, so that the silane is completely vaporized, the liquid is reduced, the effect on the results of the metering instrument is small, and the instrument measurement is more accurate.
[0035] In this embodiment, the second heat exchanger 3 can lower the temperature of the gaseous silane sent from the granular silicon production system, so that the consumption of ethylene refrigerant can be reduced when entering the demethanizer 41, and the separation efficiency can be improved. The low-temperature silane gas discharged from the demethanizer 41 is heated to room temperature and can be sent to the silane gas device condensation system together with the silane gas prepared by the silane gas device, and first enters the adsorption tank to adsorb boron and phosphorus, and further remove impurities in the silane gas.
[0036] The separation device 4 includes a demethanizer 41, which includes an air inlet and an air outlet (the air inlet is arranged at the upper part of the demethanizer 41, and the air outlet is arranged at the middle part of the demethanizer 41), the air inlet of the demethanizer 41 is connected to the shell side outlet of the second heat exchanger 3, and the air outlet of the demethanizer 41 is connected to the tube side inlet of the second heat exchanger 3.
[0037] In this embodiment, the mixed gas is purified by the demethanizer 41 to separate the low-temperature silane gas, and then the low-temperature silane gas is introduced into the tube-side flow channel of the second heat exchanger 3 to cool the mixed gas in the shell-side flow channel of the second heat exchanger 3, thereby reducing the consumption of cold capacity in the demethanizer 41; the low-temperature silane gas after heat exchange is transported to the condensation system of the silane gas device for secondary separation and purification, and then participates in the production of granular silicon. The demethanizer 41 can increase the silane gas concentration and the purity of silane recovered from granular silicon.
[0038] The separation device 4 also includes a sixth heat exchanger 43, and the demethanizer 41 also includes a liquid discharge port and a gas reflux port (the liquid discharge port and the gas reflux port are both arranged at the lower part of the demethanizer 41); the shell side inlet of the sixth heat exchanger 43 is connected to the Freon liquid source, and the shell side outlet of the sixth heat exchanger 43 is connected to the Freon liquid discharge pipe 46; the tube side inlet of the sixth heat exchanger 43 is connected to the liquid discharge port of the demethanizer 41, and the tube side outlet of the sixth heat exchanger 43 is connected to the gas reflux port of the demethanizer 41.
[0039] In this embodiment, the Freon liquid source is transported to the sixth heat exchanger 43 through the Freon transport pipe, and the Freon in the sixth heat exchanger 43 is transported to the Freon recovery device through the Freon drain pipe 46 for recycling.
[0040] The separation device 4 also includes a fifth heat exchanger 42, and the demethanizer 41 also includes a gas discharge port and a liquid reflux port (the gas discharge port is arranged at the top of the demethanizer 41, and the liquid reflux port is arranged at the upper part of the demethanizer 41); the shell side inlet of the fifth heat exchanger 42 is connected to the gas discharge port of the demethanizer 41, and the shell side outlet of the fifth heat exchanger 42 is connected to the liquid reflux port of the demethanizer 41; the tube side inlet of the fifth heat exchanger 42 is connected to an ethylene liquid source, and the tube side outlet of the fifth heat exchanger 42 is connected to an ethylene exhaust pipe 45.
[0041] In this embodiment, the ethylene liquid source is transported to the fifth heat exchanger 42 through the ethylene transport pipe, and the ethylene in the fifth heat exchanger 42 is transported to the ethylene recovery device through the ethylene exhaust pipe 45 for recycling.
[0042] The fifth heat exchanger 42 further includes a methane discharge pipe 44 , which is connected to the shell-side flow passage of the fifth heat exchanger 42 .
[0043] In this embodiment, when the mixed gas is separated in the demethanization tower 41, the temperature of the top of the tower is controlled at about -70 to -50°C by setting the fifth heat exchanger 42, and the cooling capacity in the tower is mainly provided by the fifth heat exchanger 42. The methane gas that is not liquefied in the fifth heat exchanger 42 is transported to the exhaust gas treatment device through the methane discharge pipe 44 for treatment; by setting the sixth heat exchanger 43, the mixed liquid in the lower part of the demethanization tower 4 is vaporized, and the temperature of the bottom of the tower is controlled at -70°C to -50°C.
[0044] Embodiment 2:
[0045] This embodiment provides a method for recovering silane gas using the system described in Embodiment 1, comprising the following steps:
[0046] Step 1: introducing the tail gas from polysilicon production into the liquefaction storage device 1 for liquefaction, and storing the liquefied mixed liquid;
[0047] Step 2: passing the stored mixed liquid into the first heat exchanger 2 for vaporization to obtain a mixed gas;
[0048] Step 3: The vaporized mixed gas passes through the shell-side flow channel of the second heat exchanger 3 and is introduced into the separation device 4 to separate the silane gas through purification;
[0049] Step 4: The separated silane gas is introduced into the tube-side flow channel of the second heat exchanger 3 to cool the mixed gas in the shell-side flow channel of the second heat exchanger 3 to obtain heated silane gas.
[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.
Claims
1. A silane gas recovery system for tail gas from polysilicon production, characterized in that: The invention comprises a liquefaction storage device (1) for liquefying and storing polysilicon production tail gas, a first heat exchanger (2), a second heat exchanger (3), and a separation device (4) for purifying and separating silane gas; the separation device comprises an air inlet and an air outlet; The outlet of the liquefied storage device (1) is connected to the tube-side inlet of the first heat exchanger (2), the tube-side outlet of the first heat exchanger (2) is connected to the shell-side inlet of the second heat exchanger (3), the shell-side outlet of the second heat exchanger (3) is connected to the air inlet of the separation device (4), the air outlet of the separation device (4) is connected to the tube-side inlet of the second heat exchanger (3), and the tube-side outlet of the second heat exchanger (3) is connected to a silane gas delivery pipeline.
2. A silane gas recovery system for polysilicon production tail gas according to claim 1, characterized in that: The liquefied storage device (1) comprises an exhaust gas delivery pipe (11) for delivering exhaust gas from polysilicon production, a third heat exchanger (12), a fourth heat exchanger (13) and a storage tank (14); The tail gas delivery pipe (11) is connected to the tube-side inlet of the third heat exchanger (12), the tube-side outlet of the third heat exchanger (12) is connected to the tube-side inlet of the fourth heat exchanger (13), the tube-side outlet of the fourth heat exchanger (13) is connected to the inlet of the storage tank (14), and the outlet of the storage tank (14) is connected to the tube-side inlet of the first heat exchanger (2).
3. A silane gas recovery system for polysilicon production tail gas according to claim 2, characterized in that: The shell-side inlet of the third heat exchanger (12) is connected to a hydrogen gas source, and the shell-side outlet of the third heat exchanger (12) is connected to a hydrogen exhaust pipe (16).
4. The silane gas recovery system for polysilicon production tail gas according to claim 2, characterized in that: The shell-side inlet of the fourth heat exchanger (13) is connected to a liquid nitrogen source, and the shell-side outlet of the fourth heat exchanger (13) is connected to a nitrogen exhaust pipe (15).
5. The silane gas recovery system for polysilicon production tail gas according to claim 1, characterized in that: The shell-side inlet of the first heat exchanger (2) is connected to the condensate, and the shell-side outlet of the first heat exchanger (2) is connected to the drain pipe (21).
6. The silane gas recovery system for polysilicon production tail gas according to claim 1, characterized in that: The separation device (4) comprises a demethanizer (41), the demethanizer comprising an air inlet and an air outlet, the air inlet of the demethanizer (41) being connected to the shell side outlet of the second heat exchanger (3), and the air outlet of the demethanizer (41) being connected to the tube side inlet of the second heat exchanger (3).
7. A silane gas recovery system for polysilicon production tail gas according to claim 6, characterized in that: The separation device (4) further comprises a sixth heat exchanger (43), and the demethanization tower (41) further comprises a liquid discharge port and a gas reflux port; The shell-side inlet of the sixth heat exchanger (43) is connected to a Freon liquid source, and the shell-side outlet of the sixth heat exchanger (43) is connected to a Freon liquid discharge pipe (46); The tube-side inlet of the sixth heat exchanger (43) is connected to the liquid outlet of the demethanizer (41), and the tube-side outlet of the sixth heat exchanger (43) is connected to the gas reflux port of the demethanizer (41).
8. The silane gas recovery system for polysilicon production tail gas according to claim 6, characterized in that: The separation device (4) further comprises a fifth heat exchanger (42), and the demethanization tower (41) further comprises a gas discharge port and a liquid reflux port; The shell side inlet of the fifth heat exchanger (42) is connected to the gas outlet of the demethanizer (41), and the shell side outlet of the fifth heat exchanger (42) is connected to the liquid reflux port of the demethanizer (41); The tube-side inlet of the fifth heat exchanger (42) is connected to an ethylene liquid source, and the tube-side outlet of the fifth heat exchanger (42) is connected to an ethylene exhaust pipe (45).
9. A silane gas recovery system for polysilicon production tail gas according to claim 8, characterized in that: The fifth heat exchanger (42) further comprises a methane discharge pipe (44), the methane discharge pipe being in communication with a shell-side flow passage of the fifth heat exchanger (42).