Polycrystalline silicon reduction tail gas recovery system
By adjusting the polycrystalline silicon reduction exhaust gas treatment process, first filter impurities and then use the exhaust heat for adsorption, the risk of energy consumption and explosion is solved, and efficient and clean polycrystalline silicon production is achieved.
Patent Information
- Application Number
- CN202421968327.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-14
- Publication Date
- 2025-07-29
- Estimated Expiration
- 2034-08-14
AI Technical Summary
During the polysilicon production process, the treatment process of reducing furnace exhaust gas consumes a lot of energy, and the leakage of material in the adsorption column is prone to explosion in contact with high temperature water, resulting in high production costs.
Adjust the exhaust gas treatment process of the reduction furnace, first filter impurities through a silicon powder filter and then directly enter the adsorption column, use the heat of the exhaust gas for adsorption, avoid the use of high-temperature water, and recover heat through the exhaust gas cooling device and the recovery condensation system, and finally recover hydrogen in the adsorption column.
It reduces energy consumption, avoids leakage and explosion in the adsorption column, improves production efficiency and product quality, and achieves clean and efficient polysilicon production.
Smart Images
Figure CN223159069U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of polysilicon production, and particularly relates to a polysilicon reduction tail gas recovery system. Background Art
[0002] At present, there are some problems in the production process of polysilicon, especially in the tail gas recovery and treatment process of the reduction furnace. Among them, the tail gas discharged from the reduction furnace will be processed in turn through a tail cooler - a silicon powder filter - a recovery condensation system - an adsorption column. When the reduction furnace tail gas is treated in the tail cooler, heat exchange treatment will be carried out first and high-temperature water will be used as an auxiliary to adjust the temperature range of the tail gas for the operation of subsequent processes. Then, after the tail gas is treated in turn through the silicon powder filter and the recovery condensation system, it will enter the adsorption column and the operation of recovering hydrogen from the tail gas will be carried out. During the treatment process of the adsorption column, high-temperature water will be input to assist the adsorption column in hydrogen recovery operation. Here, both the adsorption column and the previous tail cooler treatment use high-temperature water. The use of this part of high-temperature water, on the one hand, requires more energy consumption to generate high-temperature water for use, and on the other hand, the overall treatment process of the reduction furnace tail gas becomes slightly complicated. In addition, when the adsorption column is in operation, if there is material leakage in the adsorption column and the material meets high-temperature water, it is easy to explode, which will also lead to a significant increase in production costs. Content of the Utility Model
[0003] The utility model provides a polysilicon reduction tail gas recovery system to solve the problems in the prior art that more energy consumption is required in the treatment process of the reduction furnace tail gas and it is easy to explode when high-temperature water is introduced into the adsorption column due to material leakage. By adjusting the treatment process of the reduction furnace tail gas, the heat energy of the reduction furnace tail gas can be recovered and utilized, energy consumption can be reduced, and the explosion caused by the leakage of materials in the adsorption column meeting high-temperature water can be avoided.
[0004] The technical solution adopted by the utility model is as follows:
[0005] A polysilicon reduction tail gas recovery system is provided, including:
[0006] A reduction furnace for heating and melting silicon powder and generating tail gas; a silicon powder filter, the air inlet of which is communicated with the exhaust port of the reduction furnace for filtering fine silicon powder in the tail gas; an adsorption column, the air inlet of which is connected with the exhaust port of the silicon powder filter for adsorbing and recovering residual hydrides in the tail gas; a tail gas cooling device, the air inlet of which is connected with the exhaust port of the adsorption column for cooling the tail gas; a recovery condensation system having an air inlet end and an air outlet end, the air inlet end of which is communicated with the exhaust port of the tail gas cooling device, and the air outlet end of which is communicated with the air inlet of the adsorption column for condensing chlorosilane in the tail gas into a liquid.
[0007] In some embodiments of the present utility model, a first communication pipeline is provided between the exhaust port of the silicon powder filter and the intake port of the tail gas cooling device, and a valve is provided on the first communication pipeline.
[0008] In some embodiments of the present utility model, the valve is a regulating valve.
[0009] In some embodiments of the present utility model, a second communication pipeline is provided between the adsorption column and the reduction furnace for introducing the recycled hydrogen into the reduction furnace.
[0010] In some embodiments of the present utility model, the recovery condensation system includes a heat exchanger and a condenser. The intake port of the heat exchanger is communicated with the exhaust port of the tail gas cooling device, the intake port of the condenser is communicated with the exhaust port of the heat exchanger, and the exhaust port of the condenser is communicated with the intake port of the adsorption column.
[0011] In some embodiments of the present utility model, the tail gas cooling device is a tubular heat exchanger.
[0012] The beneficial effects of the present utility model are as follows:
[0013] In the present utility model, the treatment process of the tail gas discharged from the reduction furnace is adjusted. The tail gas is first filtered by the silicon powder filter to remove impurities and fine particles in the silicon powder to ensure the purity and quality of the silicon powder. Then, the tail gas filtered by the silicon powder filter is directly introduced into the interior of the adsorption column. Since the reduction furnace is used to heat and melt the silicon powder, the temperature of the tail gas generated in the reduction furnace is relatively high. At this time, the tail gas directly enters the adsorption column, and the heat contained in the tail gas is directly utilized. Compared with using high-temperature water, when there is a leakage of materials in the adsorption column, the explosion caused by the contact between the materials and the high-temperature water is avoided. After the adsorption column utilizes the tail gas filtered by the silicon powder filter, the tail gas in the adsorption column will lead to the connected tail gas cooling device, and the tail gas cooling device cools the tail gas and collects the heat therein to reduce environmental pollution. Finally, the cooled tail gas is introduced into the recovery condensation system, and the system condenses the chlorosilane contained in the tail gas in the polysilicon production into a liquid to achieve the separation of hydrogen, hydrogen chloride and chlorosilane, and then the hydrogen is introduced into the adsorption column for use. Description of the Drawings
[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art description. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0015] Figure 1Schematic diagram of the process for the polysilicon reduction tail gas recovery system Figure 1 ;
[0016] Figure 2 Schematic diagram of the process for the polysilicon reduction tail gas recovery system Figure 2 。
[0017] Reference numerals:
[0018] 1 - Reduction furnace, 2 - Silicon powder filter, 3 - Adsorption column, 4 - Tail gas cooling device, 5 - Recovery condensation system, 6 - First communication pipeline, 7 - Second communication pipeline, 8 - Control valve. Detailed implementation manners
[0019] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are the orientation or positional relationships based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.
[0020] The following disclosure provides many different implementation manners or examples for implementing different structures of the present utility model. In order to simplify the disclosure of the present utility model, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present utility model.
[0021] The embodiments of the utility model will be described in detail below with reference to the drawings.
[0022] Embodiment
[0023] As Figure 1 shown, this embodiment provides a polysilicon reduction tail gas recovery system, including:
[0024] Reduction furnace 1, the reduction furnace 1 is used for heating and melting silicon powder and generating tail gas;
[0025] Silicon powder filter 2, the air inlet of the silicon powder filter 2 is communicated with the exhaust port of the reduction furnace 1, and is used for filtering fine silicon powder in the tail gas;
[0026] Adsorption column 3, the air inlet of the adsorption column 3 is connected to the exhaust port of the silicon powder filter 2, and is used for adsorbing and recovering the remaining hydrides in the tail gas;
[0027] The tail gas cooling device 4, the air inlet of the tail gas cooling device 4 is connected to the exhaust port of the adsorption column 3, and is used for cooling the tail gas;
[0028] The recovery and condensation system 5, the recovery and condensation system 5 has an air inlet end and an air outlet end, the air inlet end of the recovery and condensation system 5 is communicated with the exhaust port of the tail gas cooling device 4, and the air outlet end of the recovery and condensation system 5 is communicated with the air inlet of the adsorption column 3, and is used for condensing the chlorosilane in the tail gas into a liquid.
[0029] After the reduction furnace 1 heats and melts the silicon powder in the furnace, the generated tail gas will be discharged through its own exhaust port and enter the silicon powder filter 2. This step is different from the existing treatment method of the tail gas of the reduction furnace 1. In the existing tail gas treatment, after the tail gas is discharged from the reduction furnace 1, it first enters the tail gas cooling device 4 for heat exchange and cooling treatment, and then passes through the silicon powder filter 2 for filtration. In this embodiment, the impurities and fine particles in the silicon powder are first filtered through the silicon powder filter 2, and then passed into the adsorption column 3 first, aiming to utilize the heat contained in the tail gas in advance. The way of adsorbing and utilizing the heat in the tail gas by the adsorption column is as follows: during the adsorption process of the adsorption column, the gas molecules move towards the solid surface, and their molecular movement speed will be greatly reduced, so heat is released. This phenomenon of heat release is called adsorption heat. The adsorption heat of physical adsorption is equal to the condensation heat of the adsorbate plus the wetting heat, generally ranging from a few hundred to several thousand joules per mole, and the maximum does not exceed 40 kJ / mol. The adsorption heat of the chemical adsorption process is larger than that of the physical adsorption process, generally 84 - 417 kJ / mol. This means that when the tail gas discharged from the polysilicon enters the adsorption column, whether it is physical adsorption or chemical adsorption, heat will be released, that is, when the tail gas is discharged from the silicon powder filter 2 and enters the adsorption column 3, only the heat of the tail gas is absorbed and utilized, and its effect is equivalent to that of a heat exchanger, and the heat of the tail gas can be transferred to the adsorption column, which realizes the replacement of the high-temperature water required for the hydrogen recovery absorption and desorption process in the process of the adsorption column 3. When the adsorption column 3 leaks materials, it can avoid the explosion caused by the contact between the material and the high-temperature water, and also saves the energy consumption required for the high-temperature water. Finally, the tail gas discharged from the adsorption column 3 is sequentially processed by the tail gas cooling device 4 and the recovery and condensation system 5, and then passed into the adsorption column 3 to complete the adsorption of impurities, so as to achieve the purification and recovery of hydrogen.
[0030] Further, as Figure 2 shown, a first communication pipeline 6 is provided between the exhaust port of the silicon powder filter 2 and the air inlet of the tail gas cooling device 4, and a valve is provided on the first communication pipeline 6.
[0031] After the tail gas of the reduction furnace 1 is treated by the silicon powder filter 2, it is discharged from the exhaust port of the silicon powder filter 2. At this time, there are two circulation paths for the tail gas. The first path is the silicon powder filter 2 - adsorption column 3 - tail gas cooling device 4 - recovery condensation system 5 - adsorption column 3. The second path is that while the first path maintains the tail gas transportation, the tail gas will also be discharged from the first connecting pipeline 6. The tail gas discharged through the second path will directly lead to the tail gas cooling device 4, and then sequentially pass through the recovery condensation system 5 and the adsorption column 3 for treatment. Compared with the situation where the tail gas can only be transported through the first path, the expansion of the second path not only makes the heat of the tail gas reach reasonable utilization, but also improves the efficiency of tail gas treatment. In addition, the tail gas that has been treated by the recovery condensation system 5 and enters the adsorption column 3 is then purified and recovered for hydrogen in the tail gas through corresponding treatment methods in the adsorption column 3. It should be noted that the tail gas treatment process here is not connected to the tail gas that directly enters the adsorption column 3 through the silicon powder filter 2 for heat recovery and utilization in the early stage, that is, these two processes do not affect each other by being connected in series. In the specific implementation scenario, they are distinguished through different pipelines to avoid the tail gas connection between the two, which may affect the recovery and treatment of the tail gas.
[0032] Further, the valve is a regulating valve 8.
[0033] The regulating valve 8 is used to regulate process parameters such as the medium flow rate, pressure, temperature, and liquid level in the field of industrial automation process control. According to the control signal in the automation system, the opening of the regulating valve 8 is automatically adjusted, thereby realizing the regulation of the medium flow rate, pressure, temperature, and liquid level. After selecting the regulating valve 8, it can be adjusted according to the actual working conditions of the adsorption column 3. For example, when the amount of tail gas introduced into the adsorption column 3 exceeds the amount of tail gas required by the adsorption column 3, the regulating valve 8 can be adjusted so that the excess tail gas filtered and discharged from the silicon powder filter 2 can enter the tail gas cooling device 4 for treatment through another path controlled by the regulating valve 8.
[0034] Further, as Figure 1 and Figure 2 shown, a second connecting pipeline 7 is provided between the adsorption column 3 and the reduction furnace 1 for introducing the recovered hydrogen into the reduction furnace 1.
[0035] The second connecting pipeline 7 can recover the hydrogen in the adsorption column 3 for use in the reduction furnace 1, specifically used in the following aspects:
[0036] 1. Hydrogen replacement during the start-up and shutdown of the reduction furnace 1: During the start-up and shutdown of the reduction furnace 1, hydrogen replacement in the furnace is required to ensure the smooth progress of the production process;
[0037] 2. Hydrogen purging during the regeneration of the adsorption column 3 for tail gas recovery: When the adsorption column 3 needs to be regenerated, hydrogen is required for purging to ensure the smooth progress of the regeneration process of the adsorption column 3;
[0038] 3. Hydrogen sealing and pressure feeding applications in the rectification tank area: In the rectification tank area, hydrogen is used for hydrogen sealing and pressure feeding, which is crucial for maintaining the stability of the production process and product quality.
[0039] Through effective hydrogen recovery and utilization, not only can production costs be reduced, but environmental pollution can also be minimized, product quality can be improved, and hydrogen can regulate the atmosphere in the silicon furnace, reduce the impact of impurity gases, prevent the formation of surface catalysts and impurities, thereby improving the purity and quality of the crystals and achieving clean, efficient, and low-energy consumption in polysilicon production.
[0040] Furthermore, the recovery and condensation system 5 includes a heat exchanger and a condenser. The inlet of the heat exchanger is connected to the exhaust port of the tail gas cooling device 4, the inlet of the condenser is connected to the exhaust port of the heat exchanger, and the exhaust port of the condenser is connected to the inlet of the adsorption column 3.
[0041] The heat exchanger in the recovery and condensation system 5 is connected to the exhaust port of the tail gas cooling device 4. After the tail gas cooling device 4 cools and processes the tail gas, the tail gas then enters the heat exchanger through the exhaust port of the tail gas cooling device 4 and the inlet of the heat exchanger. The heat exchanger transfers the remaining heat in the tail gas to cooling water or other cooling media. Meanwhile, the tail gas processed by the heat exchanger then passes through the connected condenser to condense the water vapor contained in the tail gas into a liquid.
[0042] In this embodiment, the recovery and condensation system 5 further includes a pretreatment system, a water storage system, and a control and monitoring system. The pretreatment system mainly includes devices such as filters and demisters. Before the tail gas enters the heat exchanger and condenser, it first passes through the pretreatment system to remove impurities and droplets therein. This step can ensure the smooth progress of the subsequent treatment process and prevent impurities and droplets from causing blockage or corrosion to the equipment and pipelines. After the tail gas is discharged from the pretreatment system and processed by the heat exchanger and condenser, the condensed water enters the water storage system under the action of gravity. In the water storage system, the water can be used for other purposes or directly discharged after further treatment and clarification. The final control and monitoring system is to monitor and control the operating status of the equipment in real time to ensure the normal operation and safety of the equipment. At the same time, according to actual needs, the operating parameters of the equipment can be adjusted and optimized to improve the operating efficiency and stability of the equipment. Among them, an online cleaning device is also included. This device includes a first cleaning pipeline and a second cleaning pipeline, which are used to realize the online cleaning of the gas-gas heat exchanger and the brine heat exchanger, without the need to disassemble and clean after the tail gas recovery system is shut down, reducing the safety risk of the tail gas recovery and condensation system 5 and maintaining the continuous and stable operation of the tail gas recovery and condensation system 5, thereby achieving the efficient reuse of liquid chlorosilane.
[0043] Furthermore, the tail gas cooling device 4 is a tubular heat exchanger.
[0044] The tubular heat exchanger is composed of a series of pipes. The fluid flows inside the pipes and heat exchange occurs through the pipe walls. This heat exchanger has the advantages of simple structure, high temperature and high pressure resistance, and wide application range. It is suitable for occasions with large flow rates and high heat transfer coefficients. In this embodiment, the flow rate of the tail gas is large and the flow velocity is fast, so it is suitable to use a tubular heat exchanger. It should be noted that, as shown in the attached Figure 1 and attached Figure 2 figures, in the process of the tail gas cooling device 4, there is a step of hot water in and hot water out. In this step, the way of hot water in and hot water out is essentially the same as the cooling method of cold water in and hot water out, both of which are used to achieve the heat exchange effect. The only difference is that the temperature of the hot water when it enters is higher than that of the cold water when it enters in the latter case, and the temperature of the hot water when it exits is higher than the temperature of the hot water when it enters in the former case. Generally speaking, the essence of achieving heat exchange is the same.
[0045] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Without conflict, the embodiments of this application and the features in the embodiments can be arbitrarily combined with each other. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A polysilicon reduction tail gas recovery system, characterized in that, Comprising: A reduction furnace for heating and melting silicon powder and generating tail gas; A silicon powder filter, the air inlet of which is communicated with the exhaust port of the reduction furnace for filtering fine silicon powder in the tail gas; An adsorption column, the air inlet of which is connected to the exhaust port of the silicon powder filter for adsorbing and recovering residual hydrides in the tail gas; A tail gas cooling device, the air inlet of which is connected to the exhaust port of the adsorption column for cooling the tail gas; A recovery and condensation system having an air inlet end and an air outlet end, the air inlet end of the recovery and condensation system is communicated with the exhaust port of the tail gas cooling device, and the air outlet end of the recovery and condensation system is communicated with the air inlet of the adsorption column for condensing chlorosilane in the tail gas into a liquid.
2. The polysilicon reduction tail gas recovery system according to claim 1, characterized in that, A first communication pipeline is provided between the exhaust port of the silicon powder filter and the air inlet of the tail gas cooling device, and a valve is provided on the first communication pipeline.
3. The polysilicon reduction tail gas recovery system according to claim 2, wherein The valve is a regulating valve.
4. The polysilicon reduction tail gas recovery system according to claim 1, characterized in that A second communication pipeline is provided between the adsorption column and the reduction furnace for introducing the recovered hydrogen into the reduction furnace.
5. The polysilicon reduction tail gas recovery system according to claim 1, wherein The recovery and condensation system includes a heat exchanger and a condenser, the air inlet of the heat exchanger is communicated with the exhaust port of the tail gas cooling device, the air inlet of the condenser is communicated with the exhaust port of the heat exchanger, and the air outlet of the condenser is communicated with the air inlet of the adsorption column.
6. The polysilicon reduction tail gas recovery system according to claim 1, wherein, The tail gas cooling device is a tubular heat exchanger.