Reduction furnace heat recovery device, polycrystalline silicon reaction furnace and polycrystalline silicon production system

Abstract

This utility model provides a heat recovery device for a reduction furnace, a polycrystalline silicon reactor, and a polycrystalline silicon production system, which can reduce heat loss during the heat recovery process of the reduction furnace, thereby reducing equipment and operating costs. The heat recovery device for the reduction furnace includes a cold hydrogenation vaporizer, a first flash tank, a second flash tank, and a cooling jacket for the reduction furnace. The inlet of the first flash tank is connected to the outlet of the cold hydrogenation vaporizer, and the gas phase outlet of the first flash tank is connected to a second saturated steam network. The inlet of the second flash tank is connected to the liquid phase outlet of the first flash tank, and the gas phase outlet of the second flash tank is connected to the second saturated steam network. The cooling jacket for the reduction furnace is located outside the polycrystalline silicon reduction furnace; the water inlet of the cooling jacket is connected to the liquid phase outlet of the second flash tank, and the water outlet of the cooling jacket is connected to the inlet of the second flash tank. The inlet of the second flash tank is also connected to an external condensate pipe.

Description

Technical Field

[0001] This utility model relates to the field of polysilicon production technology, and in particular to a heat recovery device for a reduction furnace, a polysilicon reactor, and a polysilicon production system. Background Technology

[0002] The modified Siemens process for producing polycrystalline silicon uses trichlorosilane as a raw material, which is reduced by hydrogen at high temperatures (1080℃~1100℃). This process offers advantages such as high safety, high purity, high quality, and stable performance. To reduce energy consumption during polycrystalline silicon production, it is necessary to improve the efficiency of heat recovery and utilization.

[0003] Steam consumption in the modified Siemens process accounts for approximately 3% to 5% of the total energy consumption in polysilicon production. Of this, the cold hydrogenation and reduction processes account for 15% and 20% of the total system steam consumption, respectively, totaling one-third. Therefore, when recovering and utilizing heat from the polysilicon production process, the recovered heat is typically used to generate steam for reuse within the polysilicon production process.

[0004] Flash tanks and steam pipelines are important devices for heat recovery and utilization in the polysilicon production process. The heat-generating process uses water as a medium to carry heat to the flash tank, where it is depressurized and cooled to generate supersaturated steam. Then, water and steam are separated, and the obtained steam is redistributed through a unified pipeline network to enter the downstream heating process.

[0005] like Figure 1 As shown, Figure 1The existing flowchart for heat recovery from a polycrystalline silicon reactor is as follows: External makeup water L1 enters a low-temperature condensate tank A1 at atmospheric pressure, where it mixes with the hot water from the reboiler of the cold hydrogenation coarse fractionation tower. To ensure the safe operation of the low-temperature condensate tank A1, the steam inside the tank is cooled and condensed into low-temperature water via heat exchanger A2 (cooling water inlet temperature 28℃, outlet temperature 40℃~45℃), which is then returned to the low-temperature condensate tank A1. The water outlet from the low-temperature condensate tank (temperature 110℃~120℃) is pressurized by the raw material booster pump A6 and enters the raw material horizontal tank A3, where it mixes with the liquid from other processes (temperature 110℃~120℃). The mixed hot water enters the reduction flash evaporation tank A4, and the 0.38MPa, 150℃ steam generated after flash evaporation enters the external pipeline network LS1 of the reduction zone. The 150°C effluent from the reduction flash tank is pumped by reduction booster pump A7 into the furnace cylinder and chassis of reduction furnace A5 to cool them. The cooled furnace cylinder water, at 170°C, returns to the reduction flash tank A4. Since the reduction flash tank A4 produces steam, it requires external replenishment of 70°C condensate water L2.

[0006] The above-mentioned heat recovery methods suffer from heat loss, increased equipment costs, and increased operating costs, for the following reasons:

[0007] (1) The raw materials and cold hydrogenation water directly enter the low-temperature condensate tank A1, without realizing the cascade heat recovery and utilization.

[0008] (2) The water entering the reduction flash tank includes: ① water from the raw material horizontal tank A3, with a temperature of 110~120℃; ② furnace water, with a temperature of 170℃; ③ external condensate, with a temperature of 70℃. The three parts of water have a large temperature difference, and there is a large heat loss after mixing.

[0009] (3) In order to ensure that 150°C saturated steam is generated in the reduction flash tank A4, the amount of saturated steam generated at one time will be reduced, and the amount of water circulating in the reduction flash tank A4 will be increased.

[0010] (4) In order to ensure the safe operation of the cryogenic condenser, steam condensation heat exchange needs to be added at the top of the tank, which consumes the steam heat of the system.

[0011] (5) The top of the atmospheric pressure condensate receiving tank located in the raw material and cold hydrogenation workshop is cooled by circulating water / air cooling. It requires 1216 tons of circulating water and a 7.5kW air-cooled fan per hour to cool down, which increases the equipment cost and operating cost of the entire system. Utility Model Content

[0012] The technical problem to be solved by this utility model is to address the above-mentioned deficiencies in the existing heat recovery technology between the cold hydrogenation and reduction processes of polycrystalline silicon, and to provide a heat recovery device for a reduction furnace, a polycrystalline silicon reactor, and a polycrystalline silicon production system, which can reduce heat loss during the heat recovery process of the reduction furnace and reduce equipment and operating costs.

[0013] In a first aspect, this utility model provides a heat recovery device for a reduction furnace, comprising a cold hydrogenation vaporizer, a first flash tank, a second flash tank, and a reduction furnace cooling jacket. The inlet of the cold hydrogenation vaporizer is connected to a first saturated steam network. The inlet of the first flash tank is connected to the outlet of the cold hydrogenation vaporizer, and the gas phase outlet of the first flash tank is connected to a second saturated steam network. The inlet of the second flash tank is connected to the liquid phase outlet of the first flash tank, and the gas phase outlet of the second flash tank is connected to the second saturated steam network. The reduction furnace cooling jacket is disposed outside the polycrystalline silicon reduction furnace and is used to cool the furnace wall; the water inlet of the reduction furnace cooling jacket is connected to the liquid phase outlet of the second flash tank, and the water outlet of the reduction furnace cooling jacket is connected to the inlet of the second flash tank. The inlet of the second flash tank is also connected to an external condensate pipe.

[0014] In some embodiments, the inlet of the second flash tank is connected to the liquid phase outlet of the first flash tank via a first manifold; the outlet of the reduction furnace cooling jacket is connected to the inlet of the second flash tank after being connected to the first manifold; and the external condensate pipe is connected to the inlet of the second flash tank after being connected to the first manifold.

[0015] In some embodiments, the outlet of the reduction furnace cooling jacket is located above the inlet of the reduction furnace cooling jacket.

[0016] In some embodiments, a drain valve is provided between the inlet of the first flash tank and the outlet of the cold hydrogen vaporizer.

[0017] In some embodiments, a first booster pump is provided between the liquid phase outlet of the first flash tank and the first manifold.

[0018] In some embodiments, a second booster pump is provided between the water inlet of the reduction furnace cooling jacket and the liquid phase outlet of the second flash tank.

[0019] In some embodiments, a third booster pump is provided between the external condensate pipe and the first manifold.

[0020] In some embodiments, a second manifold is provided between the vapor phase outlet of the first flash tank and the second saturated steam network; the vapor phase outlet of the second flash tank is connected to the second saturated steam network through the second manifold.

[0021] Therefore, the reduction furnace heat recovery device provided in this embodiment of the invention, by setting up a cold hydrogenation vaporizer and a first flash tank, and connecting the inlet of the cold hydrogenation vaporizer to a first saturated steam pipeline, and the inlet of the first flash tank to the outlet of the cold hydrogenation vaporizer, allows the steam-water mixture generated by the cold hydrogenation vaporizer to be input into the first flash tank to generate first saturated steam. Thus, heat from the polysilicon production process can be recovered through the first saturated steam. By setting up a second flash tank, connecting the inlet of the second flash tank to the liquid phase outlet of the first flash tank, and connecting the gas phase outlet of the second flash tank to a second saturated steam pipeline, hot water generated in the first flash tank can be transported to the second flash tank to generate second saturated steam, thereby recovering heat from the polysilicon production process through the second saturated steam. By setting up a cooling jacket for the reduction furnace, which is located outside the polycrystalline silicon reduction furnace, the inlet of the cooling jacket is connected to the liquid phase outlet of the second flash tank, and the outlet is connected to the inlet of the second flash tank. Hot water generated in the second flash tank can flow into the cooling jacket to recover heat from the polycrystalline silicon reduction furnace. This heat then flows back to the second flash tank, where it continues to generate second saturated steam. The inlet of the second flash tank is also connected to an external condensate pipe, allowing for water replenishment to maintain the normal circulation of the reduction furnace heat recovery device. Compared to existing technologies, the reduction furnace heat recovery device provided in this embodiment has a smaller inlet water temperature difference in the first flash tank, avoiding significant heat loss due to large inlet water temperature differences. Furthermore, compared to existing technologies, this embodiment eliminates the low-temperature condensate tank and the circulating water / air-cooled heat exchanger at its top, saving equipment and operating costs.

[0022] Secondly, this utility model embodiment also provides a polycrystalline silicon reactor, which includes a polycrystalline silicon reduction furnace and the reduction furnace heat recovery device mentioned in the first aspect. The polycrystalline silicon reduction furnace is connected to a hydrogen conveying pipeline and a trichlorosilane conveying pipeline, respectively.

[0023] Thirdly, this utility model embodiment also provides a polycrystalline silicon production system, which includes the polycrystalline silicon reactor and the trichlorosilane synthesis furnace mentioned in the second aspect. The trichlorosilane synthesis furnace is connected to the polycrystalline silicon reduction furnace of the polycrystalline silicon reactor via a trichlorosilane conveying pipeline.

[0024] The polysilicon reactor and polysilicon production system described above have the same beneficial technical effects as the reduction furnace heat recovery device provided in some of the above embodiments, and will not be described again here. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of this utility model, the accompanying drawings used in some embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only drawings of some embodiments of this utility model, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this utility model.

[0026] Figure 1 A flowchart for recovering heat from a polycrystalline silicon reactor, provided by existing technology;

[0027] Figure 2 This is a schematic diagram of a heat recovery device for a reduction furnace provided in an embodiment of the present invention.

[0028] 1-Cold hydrogenation vaporizer; 2-First flash tank; 3-Second flash tank; 4-Reduction furnace cooling jacket; 5-Drain valve; 6-First booster pump; 7-Second booster pump; 8-Third booster pump; A1-Low-temperature condensate tank; A2-Heat exchanger; A3-Raw material horizontal tank; A4-Reduction flash tank; A5-Reduction furnace; A6-Raw material booster pump; A7-Reduction booster pump. Detailed Implementation

[0029] The technical solutions of some embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments provided by this utility model, all other embodiments obtained by those skilled in the art are within the protection scope of this utility model.

[0030] Where there is no conflict, the various embodiments of this utility model and the features thereof can be combined with each other.

[0031] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." Furthermore, the specific features, structures, materials, or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

[0032] In describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be interpreted broadly; for example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. The embodiments of the utility model described herein are not necessarily limited to the content of this document.

[0033] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0034] Example 1:

[0035] like Figure 2 As shown, this utility model embodiment provides a heat recovery device for a reduction furnace. The prefabricated chamber is used in polysilicon production to recover heat from the reduction furnace.

[0036] like Figure 2 As shown, the reduction furnace heat recovery device includes a cold hydrogenation vaporizer 1, a first flash tank 2, a second flash tank 3, and a reduction furnace cooling jacket 4. The inlet of the cold hydrogenation vaporizer 1 is connected to the first saturated steam network LS2. The inlet of the first flash tank 2 is connected to the outlet of the cold hydrogenation vaporizer 1, and the vapor phase outlet of the first flash tank 2 is connected to the second saturated steam network LS3. The inlet of the second flash tank 3 is connected to the liquid phase outlet of the first flash tank 2, and the vapor phase outlet of the second flash tank 3 is connected to the second saturated steam network LS3. The reduction furnace cooling jacket 4 is located outside the polycrystalline silicon reduction furnace and is used to cool the furnace wall. The water inlet of the reduction furnace cooling jacket 4 is connected to the liquid phase outlet of the second flash tank 3, and the water outlet of the reduction furnace cooling jacket 4 is connected to the inlet of the second flash tank 3. The inlet of the second flash tank 3 is also connected to an external condensate pipe L3.

[0037] The operation process of the heat recovery device for the reduction furnace is as follows: The first saturated steam in the first saturated steam pipeline LS2 enters the cold hydrogen vaporizer 1, and after sufficient heat exchange in the cold hydrogen vaporizer 1, it becomes a water-steam mixture. The water-steam mixture enters the first flash tank 2 for flash evaporation, and the second saturated steam generated at the gas phase outlet of the first flash tank 2 enters the second saturated steam pipeline LS3 for recovery. The hot water discharged from the liquid phase outlet of the first flash tank 2 enters the second flash tank 3 for flash evaporation, and the third saturated steam generated at the gas phase outlet of the second flash tank 3 enters the second saturated steam pipeline LS3 for recovery. The hot water discharged from the liquid phase outlet of the second flash tank 3 enters the reduction furnace cooling jacket 4 to cool and heat the furnace cylinder and chassis of the polycrystalline silicon reduction furnace, and then exits from the outlet of the reduction furnace cooling jacket 4, and then re-enters the second flash tank 3 for flash evaporation. The condensate replenished by the external condensate pipeline L3 also enters the second flash tank 3 to replenish the water in the second flash tank 3.

[0038] For example, neither the first flash tank 2 nor the second flash tank 3 contains heat transfer elements such as gas-liquid separators, heating coils or jackets.

[0039] In some examples, the temperature of the second saturated steam generated at the vapor phase outlet of the first flash tank 2 is greater than 140°C and the pressure is greater than 0.36 MPa, while the temperature of the hot water discharged from the liquid phase outlet of the first flash tank 2 is greater than 140°C. The temperature of the third saturated steam generated at the vapor phase outlet of the second flash tank 3 is greater than 140°C and the pressure is greater than 0.36 MPa, while the temperature of the hot water discharged from the liquid phase outlet of the second flash tank 3 is greater than 140°C. The temperature of the hot water discharged from the outlet of the reduction furnace cooling jacket 4 is greater than 160°C.

[0040] The application of the heat recovery device for the reduction furnace in actual production is described below: The pressure of the first saturated steam in the first saturated steam pipeline LS2 is 1 MPa, and the temperature is 184.1℃. After sufficient heat exchange in the cold hydrogenation vaporizer 1, the first saturated steam becomes a water-vapor mixture at 160℃. The water-vapor mixture can enter the first flash tank 2 under its own pressure. Alternatively, a fourth booster pump can be installed between the cold hydrogenation vaporizer 1 and the first flash tank 2 to pressurize the water-vapor mixture before it is input into the first flash tank 2.

[0041] After the water vapor mixture enters the first flash tank 2, it undergoes flash evaporation. The pressure of the second saturated steam generated at the gas phase outlet of the first flash tank 2 is 0.38 MPa and the temperature is 150°C. The second saturated steam enters the second saturated steam pipeline LS3 for recovery. The temperature of the hot water discharged from the liquid phase outlet of the first flash tank 2 is about 150°C.

[0042] The hot water discharged from the liquid phase outlet of the first flash tank 2 enters the second flash tank 3 for flash evaporation. The pressure of the third saturated steam generated at the gas phase outlet of the second flash tank 3 is 0.38 MPa and the temperature is 150°C. The third saturated steam enters the second saturated steam pipeline LS3 for recovery. The temperature of the hot water discharged from the liquid phase outlet of the second flash tank 3 is approximately 150°C.

[0043] The hot water discharged from the liquid phase outlet of the first flash tank 2 enters the cooling jacket 4 of the reduction furnace and its temperature rises to 170°C. After mixing with the condensate water replenished by the external condensate water pipe L3 and the hot water discharged from the liquid phase outlet of the first flash tank 2, it enters the second flash tank 3 again for flash evaporation.

[0044] The above process is repeated continuously, so that the heat recovery device of the reduction furnace can continuously recover the heat of the polycrystalline silicon reduction furnace.

[0045] Compared with the existing technology, the present technical solution has the following beneficial effects:

[0046] First, the low-temperature condensate tank A1 at atmospheric pressure has been eliminated. The incoming water from the cold hydrogen vaporizer 1 does not need to directly enter the low-temperature condensate tank A1 at atmospheric pressure, thus avoiding the problem of large heat loss caused by the large temperature difference of the incoming water.

[0047] Secondly, the elimination of the circulating water / air-cooled heat exchanger at the top of the cryogenic condensate tank A1 can save 1216 tons / hour of circulating water consumption during the operation of the unit, as well as the electricity consumption of a 7.5kW air-cooled fan. This also saves on the cost of the aforementioned equipment and reduces the heat generated during heat exchange in the circulating water / air-cooled heat exchanger to ensure the safe operation of the cryogenic condensate tank A1.

[0048] Third, the incoming water from the raw material horizontal tank A3 to the reduction flash tank A4 has been eliminated because its temperature is only 110~120℃, which is significantly different from the furnace water return temperature of 170℃. Mixing the two before entering the reduction flash tank A4 would result in substantial energy loss. This technical solution reduces steam energy loss by mixing the incoming water (150℃) from the cold hydrogenation vaporizer 1 with the furnace water return (170℃).

[0049] Fourth, in order to ensure that the first flash tank 2 flashes out saturated steam at 150℃, the temperature difference of the incoming water in the first flash tank 2 in this technical solution is small, which can increase the amount of saturated steam generated in a single flash, reduce the amount of water circulating in the first flash tank 2, and improve the flashing efficiency of the first flash tank 2.

[0050] The inventors of this application have calculated the energy-saving effect of this technical solution in practical application: Compared with the prior art, the reduction furnace heat recovery device can recover 10.29 × 10⁶ KJ of heat per hour, and the amount of steam converted from the recovered heat energy is 3.3 t / h. Based on a steam price of 102 yuan / t and a pipeline heat loss coefficient of 0.85, the annual benefit is 2.2889 million yuan. The low-temperature condensate tank A1 and heat exchanger A2 in the prior art can be decommissioned, saving 1216 t / h of circulating water and 7.5 kW·h / h of electricity. Based on a circulating water cost of 0.113 yuan / t and an electricity price of 0.234 yuan / kW·h, the annual cost saving is 1.1133 million yuan. After comprehensive calculation, the project can save 3.4022 million yuan annually after implementation.

[0051] In summary, the heat recovery device for reduction furnaces provided in this embodiment of the invention can reduce heat loss during the heat recovery process of reduction furnaces, thereby reducing equipment costs and operating costs.

[0052] Therefore, the reduction furnace heat recovery device provided in this embodiment of the present invention, by setting up a cold hydrogenation vaporizer 1 and a first flash tank 2, and connecting the inlet of the cold hydrogenation vaporizer 1 to the first saturated steam network LS2, and the inlet of the first flash tank 2 to the outlet of the cold hydrogenation vaporizer 1, can input the steam-water mixture generated by the cold hydrogenation vaporizer 1 into the first flash tank 2 to generate first saturated steam in the first flash tank 2. Thus, heat from the polysilicon production process can be recovered through the first saturated steam. By setting up a second flash tank 3, connecting the inlet of the second flash tank 3 to the liquid phase outlet of the first flash tank 2, and connecting the gas phase outlet of the second flash tank 3 to the second saturated steam network LS3, hot water generated by the first flash tank 2 can be transported to the second flash tank 3 to generate second saturated steam, thereby recovering heat from the polysilicon production process through the second saturated steam. By setting up a reduction furnace cooling jacket 4, which is located outside the polycrystalline silicon reduction furnace, the inlet of the reduction furnace cooling jacket 4 is connected to the liquid phase outlet of the second flash tank 3, and the outlet of the reduction furnace cooling jacket 4 is connected to the inlet of the second flash tank 3. Hot water generated in the second flash tank 3 can flow into the reduction furnace cooling jacket 4 to recover heat from the polycrystalline silicon reduction furnace. After flowing back to the second flash tank 3, it continues to generate second saturated steam. By also connecting the inlet of the second flash tank 3 to an external condensate pipe L3, water can be replenished to the second flash tank 3 through the external condensate pipe L3 to maintain the normal circulation of the reduction furnace heat recovery device. Compared with the prior art, in the heat recovery device for the reduction furnace provided in this embodiment of the present invention, the temperature difference of the incoming water in the first flash tank 2 is smaller, which can avoid the problem of large heat loss caused by the large temperature difference of the incoming water; and compared with the prior art, the heat recovery device for the reduction furnace provided in this embodiment of the present invention eliminates the low temperature condensate tank A1 and the circulating water / air-cooled heat exchanger on its top, which can save equipment costs and operating costs.

[0053] In some embodiments, such as Figure 2 As shown, the inlet of the second flash tank 3 is connected to the liquid phase outlet of the first flash tank 2 through the first manifold; the outlet of the reduction furnace cooling jacket 4 is connected to the inlet of the second flash tank 3 after being connected to the first manifold; the external condensate pipe L3 is connected to the inlet of the second flash tank 3 after being connected to the first manifold.

[0054] With the above settings, as Figure 2 As shown, the hot water discharged from the liquid phase outlet of the first flash tank 2, the hot water discharged from the outlet of the reduction furnace cooling jacket 4, and the condensate supplemented by the external condensate pipe L3 can be mixed before being input into the second flash tank 3, thereby reducing the temperature fluctuation of the hot water input into the second flash tank 3.

[0055] In some embodiments, such as Figure 2As shown, the outlet of the reduction furnace cooling jacket 4 is located above the inlet of the reduction furnace cooling jacket 4.

[0056] The above settings can improve the heat exchange efficiency between the water in the cooling jacket 4 of the reduction furnace and the polycrystalline silicon reduction furnace.

[0057] In some embodiments, such as Figure 2 As shown, a steam trap 5 is provided between the inlet of the first flash tank 2 and the outlet of the cold hydrogen vaporizer 1.

[0058] The steam trap 5 can prevent the steam in the cold hydrogen vaporizer 1 from directly entering the first flash tank 2, thereby improving the heat exchange efficiency of the steam in the cold hydrogen vaporizer 1.

[0059] In some embodiments, such as Figure 2 As shown, a first booster pump 6 is installed between the liquid phase outlet of the first flash tank 2 and the first manifold.

[0060] The first booster pump 6 can pressurize the hot water discharged from the liquid phase outlet of the first flash tank 2 and then pressurize it into the first manifold, and finally into the second flash tank 3.

[0061] In some embodiments, such as Figure 2 As shown, a second booster pump 7 is installed between the water inlet of the reduction furnace cooling jacket 4 and the liquid phase outlet of the second flash tank 3.

[0062] The second booster pump 7 can pressurize the hot water discharged from the liquid phase outlet of the second flash tank 3 and force it into the reduction furnace cooling jacket 4, and also force the hot water discharged from the reduction furnace cooling jacket 4 into the second flash tank 3; it can also increase the water flow rate in the reduction furnace cooling jacket 4 and improve the cooling effect on the polycrystalline silicon reduction furnace.

[0063] In some embodiments, such as Figure 2 As shown, a third booster pump 8 is installed between the external condensate pipe L3 and the first manifold.

[0064] The third booster pump 8 can pressurize the condensate in the external condensate pipe L3 and then force it into the first manifold, and finally into the second flash tank 3.

[0065] In some embodiments, such as Figure 2 As shown, a second manifold is provided between the vapor phase outlet of the first flash tank 2 and the second saturated steam network LS3; the vapor phase outlet of the second flash tank 3 is connected to the second saturated steam network LS3 through the second manifold.

[0066] With the above settings, the saturated steam generated by the first flash tank 2 and the saturated steam generated by the second flash tank 3 can be collected and input into the second saturated steam pipeline network LS3, which can reduce the number of openings that need to be set on the second saturated steam pipeline network LS3.

[0067] Example 2:

[0068] This utility model embodiment also provides a polycrystalline silicon reactor, which is used in the polycrystalline silicon production process.

[0069] The polycrystalline silicon reactor includes a polycrystalline silicon reduction furnace and the reduction furnace heat recovery device in Example 1. The polycrystalline silicon reduction furnace is connected to a hydrogen delivery pipeline and a trichlorosilane delivery pipeline, respectively.

[0070] The hydrogen delivery pipeline is used to deliver hydrogen to the polysilicon reduction furnace, and the trichlorosilane delivery pipeline is used to deliver trichlorosilane to the polysilicon reduction furnace. The hydrogen and trichlorosilane react in the polysilicon reduction furnace to generate polysilicon.

[0071] The heat recovery device for the reduction furnace can recover the heat generated during the polysilicon reduction furnace reaction and store it in steam. This can improve the heat recovery and utilization rate of the polysilicon reactor in the polysilicon production process and reduce the operating cost of the polysilicon reactor.

[0072] Example 3:

[0073] This utility model embodiment also provides a polycrystalline silicon production system, which includes the polycrystalline silicon reactor and the trichlorosilane synthesis furnace as described in embodiment 2. The trichlorosilane synthesis furnace is connected to the polycrystalline silicon reduction furnace of the polycrystalline silicon reactor through a trichlorosilane conveying pipeline.

[0074] For example, the trichlorosilane synthesis furnace is connected to a hydrogen chloride gas pipeline and a silicon powder conveying pipeline. The hydrogen chloride gas pipeline is used to supply hydrogen chloride gas to the trichlorosilane synthesis furnace, and the silicon powder conveying pipeline is used to supply silicon powder to the trichlorosilane synthesis furnace. The silicon powder and hydrogen chloride gas react in the trichlorosilane synthesis furnace to generate trichlorosilane.

[0075] The synthesized trichlorosilane is fed into a polycrystalline silicon reduction furnace through a trichlorosilane conveying pipeline for reaction.

[0076] With the above setup, the heat generated during polysilicon production can be recovered by the reduction furnace heat recovery device, thereby improving the heat recovery efficiency of the polysilicon production system and reducing the equipment and operating costs of the polysilicon production system.

[0077] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A heat recovery device for a reduction furnace, characterized in that, include: The cold hydrogen vaporizer (1) has its inlet connected to the first saturated steam pipeline; The first flash tank (2) has its inlet connected to the outlet of the cold hydrogen vaporizer (1) and its gas phase outlet connected to the second saturated steam pipeline. The second flash tank (3) has its inlet connected to the liquid phase outlet of the first flash tank (2), and its gas phase outlet connected to the second saturated steam pipeline network; and, The reduction furnace cooling jacket (4) is set outside the polysilicon reduction furnace and is used to cool the furnace wall of the polysilicon reduction furnace; the water inlet of the reduction furnace cooling jacket (4) is connected to the liquid phase outlet of the second flash tank (3), and the water outlet of the reduction furnace cooling jacket (4) is connected to the inlet of the second flash tank (3). The inlet of the second flash tank (3) is also connected to an external condensate pipe.

2. The heat recovery device for the reduction furnace according to claim 1, characterized in that, The inlet of the second flash tank (3) is connected to the liquid phase outlet of the first flash tank (2) through the first manifold; the outlet of the cooling jacket (4) of the reduction furnace is connected to the inlet of the second flash tank (3) after being connected to the first manifold; the external condensate pipe is connected to the inlet of the second flash tank (3) after being connected to the first manifold.

3. The heat recovery device for the reduction furnace according to claim 2, characterized in that, The outlet of the reduction furnace cooling jacket (4) is located above the inlet of the reduction furnace cooling jacket (4).

4. The heat recovery device for the reduction furnace according to claim 2, characterized in that, A condensate valve (5) is provided between the inlet of the first flash tank (2) and the outlet of the cold hydrogen vaporizer (1).

5. The heat recovery device for the reduction furnace according to claim 2, characterized in that, A first booster pump (6) is provided between the liquid phase outlet of the first flash tank (2) and the first manifold.

6. The heat recovery device for the reduction furnace according to claim 2, characterized in that, A second booster pump (7) is provided between the water inlet of the cooling jacket (4) of the reduction furnace and the liquid phase outlet of the second flash tank (3).

7. The heat recovery device for the reduction furnace according to claim 2, characterized in that, A third booster pump (8) is installed between the external condensate pipe and the first manifold.

8. The heat recovery device for the reduction furnace according to claim 2, characterized in that, A second manifold is provided between the vapor phase outlet of the first flash tank (2) and the second saturated steam network; the vapor phase outlet of the second flash tank (3) is connected to the second saturated steam network through the second manifold.

9. A polycrystalline silicon reactor, characterized in that, include: The polycrystalline silicon reduction furnace is connected to a hydrogen supply pipeline and a trichlorosilane supply pipeline, respectively; and, The heat recovery device for the reduction furnace according to any one of claims 1-8.

10. A polycrystalline silicon production system, characterized in that, include: The polycrystalline silicon reactor as described in claim 9; and, The trichlorosilane synthesis furnace is connected to the polycrystalline silicon reduction furnace of the polycrystalline silicon reactor via a trichlorosilane delivery pipeline.

Images