Polycrystalline silicon production reduction tail gas condensation recovery system

Abstract

The utility model discloses a polycrystalline silicon production reduction tail gas condensation recovery system, relates to the technical field of polycrystalline silicon production, and mainly aims to improve the cold energy utilization efficiency in the polycrystalline silicon tail gas recycling process. The main technical scheme of the utility model is as follows: the system for condensing and recovering the reduction tail gas in the polycrystalline silicon production comprises a pretreatment part, wherein the pretreatment part comprises a material heat exchanger, a circulating water heat exchanger and a leaching tower which are connected in sequence; the post-treatment part comprises a hydrogen heat exchanger, a chlorosilane heat exchanger, an ethylene glycol heat exchanger and a collecting tank; an exhaust port of the leaching tower, a first space of the hydrogen heat exchanger, a first space of the chlorosilane heat exchanger, the ethylene glycol heat exchanger and the collecting tank are sequentially communicated; wherein the lower end of the collecting tank, the second space of the chlorosilane heat exchanger and the spraying pipe of the leaching tower are sequentially communicated, and the upper end of the collecting tank, the second space of the hydrogen heat exchanger and the hydrogen compressor are sequentially connected.

Description

Technical Field

[0001] The utility model relates to the technical field of polysilicon production, in particular to a polysilicon production reduction tail gas condensation recovery system. Background Art

[0002] The principle of the polysilicon production process is to reduce high-purity trichlorosilane with high-purity hydrogen on a high-purity silicon core at about 1100°C to generate polysilicon deposited on the silicon core. A large amount of by-products such as H2, HCI, SiCI4, SIHCL3, SIH2CL2 and a large amount of by-product heat energy are generated in the production process. The tail gas recovery workshop mostly adopts a dry recovery process, which mainly processes the by-products and a large amount of by-product heat energy sent from the reduction workshop, including a mixed high-temperature gas of trichlorosilane, dichlorodihydrosilane, silicon tetrachloride, hydrogen and hydrogen chloride. After deep cooling, the separated hydrogen is purified and sent to the reduction workshop for use as raw material. The condensed material is sent to the distillation workshop for separation and purification again, and then sent to the reduction workshop for use as raw material.

[0003] In the above process, the reduced tail gas is cooled down in turn by circulating water heat exchanger, gas-to-gas heat exchanger and chilled brine heat exchanger, so as to achieve the purpose of separating tail gas components. This method requires a large amount of cold energy to separate the condensable components from the non-condensable components in the tail gas, which has high energy consumption and the cold energy cannot be fully utilized. Utility Model Content

[0004] In view of this, the utility model provides a polysilicon production reduction tail gas condensation recovery system, the main purpose of which is to improve the cold utilization efficiency in the process of polysilicon tail gas recovery and utilization.

[0005] In order to achieve the above purpose, the utility model mainly provides the following technical solutions:

[0006] The utility model provides a polysilicon production reduction tail gas condensation recovery system, the system comprises: a pre-processing part and a post-processing part;

[0007] The pretreatment part includes a material heat exchanger, a circulating water heat exchanger and a washing tower which are connected in sequence;

[0008] The post-processing unit includes a hydrogen heat exchanger, a chlorosilane heat exchanger, an ethylene glycol heat exchanger and a collecting tank, and the exhaust port of the elution tower, the first space of the hydrogen heat exchanger, the first space of the chlorosilane heat exchanger, the ethylene glycol heat exchanger and the collecting tank are connected in sequence;

[0009] The lower end of the collecting tank, the second space of the chlorosilane heat exchanger and the spray pipe of the elution tower are connected in sequence, and the upper end of the collecting tank, the second space of the hydrogen heat exchanger and the hydrogen compressor are connected in sequence.

[0010] The purpose of the utility model and the solution to its technical problems can also be further achieved by adopting the following technical measures.

[0011] Optionally, the post-processing unit also includes a condenser, the drain port at the lower end of the ethylene glycol heat exchanger is connected to the collecting tank via a first U-shaped tube, and the lower end side of the ethylene glycol heat exchanger, the condenser and the collecting tank are connected in sequence.

[0012] Optionally, the drain port at the lower end of the first space of the chlorosilane heat exchanger is connected to the collecting tank via a second U-shaped tube, and the lower end side of the first space of the chlorosilane heat exchanger is connected to the inlet of the ethylene glycol heat exchanger.

[0013] Optionally, an air cooler is also included, and the exhaust port of the elution tower, the air cooler, and the inlet of the first space of the hydrogen heat exchanger are connected in sequence.

[0014] Optionally, the discharge port at the lower end of the material heat exchanger is connected to the inlet of the elution tower through a third U-shaped tube.

[0015] Optionally, the drain port at the lower end of the circulating water heat exchanger is connected to the inlet of the elution tower through a fourth U-shaped tube.

[0016] By means of the above technical solution, the utility model has at least the following advantages:

[0017] The high-temperature mixed tail gas (150°C) containing chlorosilane, hydrogen chloride and hydrogen from the reduction furnace enters the material heat exchanger and the circulating water heat exchanger in turn for heat exchange, is cooled to 30 to 35°C, then enters the leaching tower, is discharged through the exhaust port of the leaching tower, and flows through the first space of the hydrogen heat exchanger, the first space of the chlorosilane heat exchanger, the ethylene glycol heat exchanger and the collection tank in turn, so that the material temperature in the collection tank is reduced to -30 to -40°C;

[0018] The condensate in the collecting tank is pumped from the lower end of the collecting tank to the second space of the chlorosilane heat exchanger to reduce the temperature of the material in the first space of the chlorosilane heat exchanger, and then reaches the spray pipe of the elution tower to be sprayed as a spray liquid;

[0019] The low-temperature hydrogen in the collection tank first enters the second space of the hydrogen heat exchanger. After reducing the temperature of the material in the first space of the hydrogen heat exchanger, the temperature of the low-temperature hydrogen rises to 8°C and then enters the hydrogen compressor for further purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic structural diagram of a polysilicon production reduction tail gas condensation recovery system provided in an embodiment of the utility model.

[0021] The figure marks in the drawings of the specification include: material heat exchanger 1, circulating water heat exchanger 2, elution tower 3, hydrogen heat exchanger 4, chlorosilane heat exchanger 5, ethylene glycol heat exchanger 6, collecting tank 7, shielded pump 8, condenser 9, first U-shaped tube 10, second U-shaped tube 11, air cooler 12, third U-shaped tube 13, fourth U-shaped tube 14. DETAILED DESCRIPTION

[0022] In order to further explain the technical means and effects adopted by the utility model to achieve the predetermined utility model purpose, the specific implementation methods, structures, features and effects of the utility model application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0023] The utility model is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, an embodiment of the utility model provides a polysilicon production reduction tail gas condensation recovery system, which includes: a pre-treatment part and a post-treatment part;

[0025] The pretreatment part includes a material heat exchanger 1, a circulating water heat exchanger 2 and a washing tower 3 which are connected in sequence;

[0026] The post-processing unit includes a hydrogen heat exchanger 4, a chlorosilane heat exchanger 5, an ethylene glycol heat exchanger 6 and a collecting tank 7, and the exhaust port of the elution tower 3, the first space of the hydrogen heat exchanger 4, the first space of the chlorosilane heat exchanger 5, the ethylene glycol heat exchanger 6 and the collecting tank 7 are connected in sequence;

[0027] The lower end of the collecting tank 7, the second space of the chlorosilane heat exchanger 5 and the spray pipe of the elution tower 3 are connected in sequence, and the upper end of the collecting tank 7, the second space of the hydrogen heat exchanger 4 and the hydrogen compressor are connected in sequence.

[0028] The working process of the polysilicon production reduction tail gas condensation recovery system is as follows:

[0029] The high-temperature mixed tail gas (150°C) containing chlorosilane, hydrogen chloride and hydrogen from the reduction furnace enters the material heat exchanger 1 and the circulating water heat exchanger 2 for heat exchange in sequence, is cooled to 30 to 35°C, then enters the elution tower 3, is discharged through the exhaust port of the elution tower 3, and flows through the first space of the hydrogen heat exchanger 4, the first space of the chlorosilane heat exchanger 5, the ethylene glycol heat exchanger 6 and the collection tank 7 in sequence, so that the material temperature in the collection tank 7 is reduced to -30 to -40°C;

[0030] The condensate in the collecting tank 7 (mainly condensed chlorosilane and hydrogen chloride) is pumped from the lower end of the collecting tank 7 to the second space of the chlorosilane heat exchanger 5 to reduce the material temperature in the first space of the chlorosilane heat exchanger 5, and then reaches the spray pipe of the elution tower 3 to be sprayed as a spray liquid;

[0031] The low-temperature hydrogen in the collecting tank 7 first enters the second space of the hydrogen heat exchanger 4, and after reducing the temperature of the material in the first space of the hydrogen heat exchanger 4, the temperature of the low-temperature hydrogen rises to 8°C, and then enters the hydrogen compressor for further purification.

[0032] In the technical solution of the utility model, the device uses the non-condensable material after cooling in the collection tank 7 as a refrigerant, the front material in the cooling process, and the condensed material as a spray liquid to remove silicon powder. The liquid at the bottom of the elution tower 3 enters the distillation tank area, making full use of the temperature difference of the materials before and after the process, and improving the cold utilization efficiency in the exhaust gas recovery process.

[0033] Specifically, it also includes a shielded pump 8 , the inlet of the shielded pump 8 is connected to the lower outlet of the collecting tank 7 , and the outlet of the shielded pump 8 is connected to the second space of the chlorosilane heat exchanger 5 .

[0034] like Figure 1 As shown, in a specific embodiment, the post-processing part also includes a condenser 9, the discharge port at the lower end of the ethylene glycol heat exchanger 6 is connected to the collecting tank 7 through a first U-shaped tube 10, and the lower end side of the ethylene glycol heat exchanger 6, the condenser 9 and the collecting tank 7 are connected in sequence.

[0035] Specifically, the material heat exchanger 1, the circulating water heat exchanger 2, the hydrogen heat exchanger 4, the chlorosilane heat exchanger 5 and the ethylene glycol heat exchanger 6 are all vertical shell-and-tube heat exchangers, and the condenser 9 is a Freon condenser 9;

[0036] Specifically, the reduction furnace tail gas material flows through the tube side of the material heat exchanger 1, the tube side of the circulating water heat exchanger 2, the tube side of the hydrogen heat exchanger 4, the tube side of the chlorosilane heat exchanger 5, and the tube side of the ethylene glycol heat exchanger 6 in sequence, and ethylene glycol flows through the shell side of the ethylene glycol heat exchanger 6 as a refrigerant;

[0037] The shell side of the material heat exchanger 1 uses 7°C hydrogen produced by the reduction tail gas recovery system as the refrigerant.

[0038] Specifically, after condensation in the ethylene glycol heat exchanger 6, the liquid phase material therein is discharged from the drain port through the first U-shaped tube 10 to the collecting tank 7. Since the first U-shaped tube 10 acts as a liquid seal, it prevents the unliquefied gas phase material from directly reaching the collecting tank 7, thereby forcing the gas phase material to first enter the condenser 9 and then enter the collecting tank 7, thereby improving the degree of material condensation.

[0039] like Figure 1As shown, in a specific embodiment, the discharge port at the lower end of the first space of the chlorosilane heat exchanger 5 is connected to the collecting tank 7 through a second U-shaped tube 11, and the lower end side of the first space of the chlorosilane heat exchanger 5 is connected to the inlet of the ethylene glycol heat exchanger 6.

[0040] In this embodiment, specifically, after condensation in the chlorosilane heat exchanger 5, the liquid phase material therein is discharged from the drain port through the second U-shaped tube 11 to the collecting tank 7. Since the second U-shaped tube 11 acts as a liquid seal, it prevents the unliquefied gas phase material from directly reaching the collecting tank 7, thereby forcing the gas phase material to first enter the tube side of the ethylene glycol heat exchanger 6 for further liquefaction.

[0041] like Figure 1 As shown, in a specific embodiment, an air cooler 12 is also included, and the exhaust port of the elution tower 3, the air cooler 12, and the inlet of the first space of the hydrogen heat exchanger 4 are connected in sequence.

[0042] In this embodiment, specifically, by using the air cooler 12, the sprayed material absorbs the coldness in the air and then enters the first space of the hydrogen heat exchanger 4 to be further cooled.

[0043] like Figure 1 As shown, in a specific embodiment, the discharge port at the lower end of the material heat exchanger 1 is connected to the inlet of the elution tower 3 through a third U-shaped tube 13 .

[0044] In this embodiment, specifically, the reduction tail gas material entering the lower end inlet of the material heat exchanger 1 includes gas phase material and liquid phase material, wherein the liquid phase material directly enters the elution tower 3 through the third U-shaped tube 13, wherein the gas phase material rises from the bottom to the top, and the temperature gradually decreases, and the gas phase material that has not yet been liquefied enters the circulating water heat exchanger 2 and is further cooled;

[0045] The third U-shaped tube 13 plays a role of liquid sealing to prevent the gas phase material from flowing to the elution tower 3 through the third U-shaped tube 13 .

[0046] like Figure 1 As shown, in a specific embodiment, the discharge port at the lower end of the circulating water heat exchanger 2 is connected to the inlet of the elution tower 3 through a fourth U-shaped tube 14 .

[0047] In this embodiment, specifically, in the tube path of the circulating water heat exchanger 2, part of the gas phase material is liquefied and refluxed, discharged from the drain port at the lower end, and enters the elution tower 3 through the fourth U-shaped tube 14, and the unliquefied gas phase material enters the elution tower 3 alone.

[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 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 reduction tail gas condensation recovery system, characterized in that: include: A pretreatment section, the pretreatment section comprising a material heat exchanger, a circulating water heat exchanger and a washing tower connected in sequence; A post-processing unit, the post-processing unit comprising a hydrogen heat exchanger, a chlorosilane heat exchanger, an ethylene glycol heat exchanger and a collecting tank, the exhaust port of the elution tower, the first space of the hydrogen heat exchanger, the first space of the chlorosilane heat exchanger, the ethylene glycol heat exchanger and the collecting tank being connected in sequence; The lower end of the collecting tank, the second space of the chlorosilane heat exchanger and the spray pipe of the elution tower are connected in sequence, and the upper end of the collecting tank, the second space of the hydrogen heat exchanger and the hydrogen compressor are connected in sequence.

2. The polysilicon production reduction tail gas condensation recovery system according to claim 1, characterized in that: The post-processing unit also includes a condenser, the drain port at the lower end of the ethylene glycol heat exchanger is connected to the collection tank through a first U-shaped tube, and the lower end side of the ethylene glycol heat exchanger, the condenser and the collection tank are connected in sequence.

3. The polysilicon production reduction tail gas condensation recovery system according to claim 2, characterized in that: The drain port at the lower end of the first space of the chlorosilane heat exchanger is connected to the collecting tank through a second U-shaped tube, and the lower end side of the first space of the chlorosilane heat exchanger is connected to the inlet of the ethylene glycol heat exchanger.

4. The polysilicon production reduction tail gas condensation recovery system according to claim 1, characterized in that: It also includes an air cooler, and the exhaust port of the elution tower, the air cooler, and the inlet of the first space of the hydrogen heat exchanger are connected in sequence.

5. The polysilicon production reduction tail gas condensation recovery system according to any one of claims 1 to 4, characterized in that: The liquid discharge port at the lower end of the material heat exchanger is connected to the inlet of the elution tower through a third U-shaped pipe.

6. The polysilicon production reduction tail gas condensation recovery system according to any one of claims 1 to 4, characterized in that: The liquid discharge port at the lower end of the circulating water heat exchanger is connected to the inlet of the elution tower through a fourth U-shaped tube.

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