Device for absorbing silane tail gas in FBR particle silicon production process

Abstract

The utility model provides a device for absorbing silane tail gas in an FBR particle silicon production process. The device comprises a leaching tower (3) for receiving the silane tail gas; an alkali liquor inlet and a clear water inlet for respectively injecting alkali liquor and clear water into the tower kettle are formed in the middle of the leaching tower (3); an alkali liquor outlet is formed in the bottom of the leaching tower (3) and is in fluid connection with a spraying device at the top of the leaching tower (3) through a heater (6); alkali liquor is discharged from the alkali liquor outlet through a waste alkali regulating valve (13); according to the utility model, through intelligent interlocking of waste lye delivery and clear water supplement, multi-stage filler optimization and hydrogen inerting protection, the problems of blockage, ignition at an explosion vent and unstable operation are solved.

Description

Technical Field

[0001] This utility model relates to a device for absorbing exhaust gas, and more particularly to a device for absorbing silane exhaust gas in the FBR particulate silicon production process. Background Technology

[0002] This section provides only background information relevant to this disclosure and is not necessarily prior art.

[0003] Silane (SiH4) is a compound containing four hydrogen atoms and one silicon atom. At room temperature and pressure, it is a colorless, toxic, flammable gas with a strong pungent odor.

[0004] In the FBR fluidized bed granular silicon production process, the silane gas production unit and the granular silicon production unit will generate tail gas containing SiH4, which contains N2, H2, SiH4, etc.; for example Figure 2 The existing technology involves introducing exhaust gas into a hollow fiberglass spray tower and absorbing it with water. However, the reaction between SiH4 and H2O in the exhaust gas is rapid and intense, producing SiO2 which easily clogs the spray nozzles. Furthermore, due to the high reaction temperature, the generated H2 is prone to spontaneous combustion with air at the top vent of the spray tower. Additionally, the SiO2 produced enters the collection tank with the spray liquid, frequently causing wear and damage to the spray pump. In summary, the shortcomings of the existing technology include:

[0005] 1. SiH4 reacts violently with water and is prone to ignition at the vent outlet of the hollow fiberglass spray tower;

[0006] 2. The spray liquid in the collection tank contains SiO2, which can easily cause the spray nozzles to become clogged and the spray pump to wear out and be damaged.

[0007] 3. Waste alkali discharge and clean water replenishment rely on manual operation, and concentration fluctuations lead to unstable absorption efficiency;

[0008] 4. The accumulation of hydrogen in the mixed exhaust gas poses an explosion risk, and there is a lack of real-time monitoring and inert interlock control.

[0009] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0010] Purpose of the invention: The technical problem to be solved by this utility model is to provide a device for silane tail gas absorption in the FBR particulate silicon production process, which addresses the shortcomings of the existing technology.

[0011] To solve the above-mentioned technical problems, this utility model discloses a device for silane tail gas absorption in the FBR particulate silicon production process, comprising:

[0012] A scrubbing tower for receiving the silane tail gas; the middle of the scrubbing tower is provided with an alkali inlet and a water inlet for injecting alkali solution and water into the tower bottom, respectively; the bottom of the scrubbing tower is provided with an alkali outlet, which is fluidly connected to the spray device at the top of the scrubbing tower through a heater; the alkali outlet also discharges alkali solution through a waste alkali regulating valve.

[0013] Furthermore, the alkali inlet is fluidly connected to the alkali tank via an alkali regulating valve, and the clean water inlet is connected to externally input clean water via a clean water regulating valve.

[0014] Furthermore, the scrubbing tower is equipped with pH and turbidity sensors inside the tower bottom, which are electrically connected to the waste alkali regulating valve and the clean water regulating valve.

[0015] Furthermore, the alkali outlet is fluidly connected to the waste alkali regulating valve via a filter and a corrosion-resistant pump.

[0016] Furthermore, the alkali outlet is fluidly connected to the input end of the heater via a filter, a corrosion-resistant pump, and a heater valve; the output end of the heater is fluidly connected to the spraying device via a spray pipe valve.

[0017] Furthermore, a silane concentration detector is installed at the tail gas inlet of the scrubbing tower, and the silane concentration detector is electrically connected to the valve of the spray pipe.

[0018] Furthermore, the scrubbing tower is provided with a packing layer, which is located between the spraying device and the tail gas inlet, for the tail gas to react with the alkaline solution.

[0019] Furthermore, a nitrogen pipe is provided at the exhaust gas inlet via a nitrogen valve, and a hydrogen concentration sensor (10) is provided at the spray device, the hydrogen concentration sensor being electrically connected to the nitrogen valve.

[0020] Furthermore, the alkali tank is used to store alkali solution, and the alkali solution is output to the outside through the alkali solution pump, forming a self-circulation.

[0021] Furthermore, the packing layer is configured as multiple segments, and its structure is one or a combination of plate structure, structured packing or random packing, and the material is metal, non-metal or polymeric biopolymer material.

[0022] Beneficial effects:

[0023] 1. By using this utility model, the reaction temperature can be controlled to ≤25~75℃, thereby reducing the formation of SiO2·nH2O colloid.

[0024] 2. Using this utility model, the silane removal rate is ≥99.9% and the outlet H2 concentration is <0.5% LEL, which can effectively reduce the ignition of the vent at the top of the scrubbing tower. Attached Figure Description

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0026] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0027] Figure 2 This is a schematic diagram of the overall structure of an exhaust gas absorption device in the prior art.

[0028] In the diagram, 1 is the alkali tank, 2 is the alkali pump, 3 is the scrubbing tower, 4 is the filter, 5 is the corrosion-resistant pump, 6 is the heater, 7 is the silane concentration detector, 8 is the pH and turbidity sensor, 9 is the packing layer, 10 is the hydrogen concentration sensor, 11 is the clean water regulating valve, 12 is the alkali regulating valve, and 13 is the waste alkali regulating valve. Detailed Implementation

[0029] The overall concept of this utility model is as follows: It provides a scrubbing tower system and method for silane tail gas, which solves the problems of blockage, explosion vent ignition and unstable operation by means of intelligent interlocking of waste alkali liquid delivery and clean water replenishment, multi-stage packing optimization and hydrogen inertization protection.

[0030] The technical solution of this utility model is as follows: A device is provided for absorbing silane tail gas in the FBR granular silicon production process, used to absorb silane-containing tail gas generated during the granular silicon production process. For example... Figure 1 As shown, this device mainly consists of an alkali tank 1, an alkali pump 2, a scrubbing tower 3, a filter 4, a corrosion-resistant pump 5, a heater 6, a silane concentration detector 7, a pH and turbidity sensor 8, a packing layer 9, a hydrogen concentration sensor 10, a clean water regulating valve 11, an alkali regulating valve 12, and a waste alkali regulating valve 13, as detailed below:

[0031] The alkali outlet of the alkali tank 1 is equipped with an alkali regulating valve 12. The alkali regulating valve 12 and the clean water regulating valve 11 are respectively connected to the bottom of the scrubbing tower 3 for feeding alkali and clean water into the bottom of the tower.

[0032] The bottom of the scrubbing tower 3 is equipped with an alkali outlet. After passing through the filter 4 and the corrosion-resistant pump 5, it is fluidly connected to the input end of the heater 6. The output end of the heater 6 is connected to the spray head at the top of the scrubbing tower 3, which is used to spray the heated mixed alkali solution downwards from the top of the scrubbing tower 3.

[0033] In one embodiment, a heater valve may be provided between the corrosion-resistant pump 5 and the heater 6.

[0034] In another embodiment, the corrosion-resistant pump 5 can be configured to return the alkali solution to the scrubbing tower via a reflux valve.

[0035] The scrubbing tower 3 is equipped with a tail gas inlet in the middle, which is used to input the silane tail gas in the FBR particulate silicon production process.

[0036] Below the spray heads and above the tail gas inlet in the scrubbing tower 3, there is a packing layer 9 for the reaction of alkaline solution and tail gas. The packing layer can be n segments, and the structure can be one or more combinations of plate structure, structured packing, random packing, etc. The structural material can be metal, non-metal, or high-molecular biopolymer material.

[0037] Between the corrosion-resistant pump 5 and the heater 6, there is also a waste alkali regulating valve 13, which is used to output the waste liquid at the bottom of the tower.

[0038] The bottom of the scrubbing tower 3 is equipped with a pH and turbidity sensor 8. The pH and turbidity sensor 8 is electrically connected to the waste alkali regulating valve 13 and the clean water regulating valve 11 to control their opening and closing.

[0039] A hydrogen concentration sensor 10 is installed at the top of the scrubbing tower 3. The hydrogen concentration sensor 10 is electrically connected to the nitrogen valve to control its opening and closing. The nitrogen valve is fluidly connected to the tail gas inlet in the middle of the scrubbing tower 3 to input nitrogen.

[0040] In use, the alkali solution in the alkali tank 1 is transported to the bottom of the scrubbing tower 3 by the first alkali pump 2. Clean water is added through the clean water regulating valve 11 on the clean water pipeline, and the alkali solution is prepared into a concentration of 1% to 80% in the bottom of the scrubbing tower 3. The alkali solution in the bottom of the tower is transported to the heater 6 through the filter 4 and the corrosion-resistant pump 5. After being heated by the heater 6, the alkali solution enters the top of the scrubbing tower 3 and is sprayed from top to bottom through the packing layer 9. The tail gas containing silane participates in the reaction in the packing layer 9 and is absorbed. The reaction products flow into the bottom of the tower with the alkali solution. Finally, the waste alkali solution is sent to the downstream for treatment through the waste alkali solution pipeline. The tail gas after scrubbing contains only nitrogen and hydrogen. After passing the test, it is discharged into the atmosphere from the top vent of the tower.

[0041] The alkaline solution in alkaline solution tank 1 can be NaOH, KOH, Ca(OH)2, Ba(OH)2, CsOH, LiOH, RbOH, etc.

[0042] The heat transfer medium for heater 6 can be steam, steam condensate, heat transfer oil, resistance wire, etc.

[0043] The tower is equipped with a packing layer 9, which can be n segments. The structure can be one or more combinations of plate structure, structured packing, random packing, etc. The structural material can be metal, non-metal or high molecular biopolymer material. A silane concentration detector 7 is installed on the exhaust gas inlet pipeline, a hydrogen concentration sensor 10 is installed on the upper part of the packing layer in the tower, and a pH & turbidity sensor 8 is installed in the tower bottom.

[0044] The alkaline solution in the bottom of the tower is transported to the top spray head via a corrosion-resistant pump 5, with a spray particle size of ≤50-150μm.

[0045] The alkaline solution in the bottom of the tower is monitored by the online pH and turbidity sensor 8. When the pH is <8.5 or the turbidity of suspended solids is >1% to 35%, the waste alkali delivery pipeline regulating valve 13 is automatically opened. At this time, the alkaline solution in the bottom of the tower is waste alkali solution and is discharged from the system. At the same time, the clear water pipeline regulating valve 11 and the alkali solution regulating valve 12 are opened to replenish and mix, maintaining the alkali solution concentration at 1% to 80%.

[0046] Hydrogen inertization control: A hydrogen concentration sensor 10 is installed on the upper part of the packing layer. The hydrogen concentration sensor 10 and the nitrogen valve are automatically controlled. When the H2 concentration is >1% LEL, nitrogen dilution is started to the safe threshold.

[0047] A silane concentration detector 7 is installed on the exhaust gas intake line. The spray volume is automatically adjusted according to the silane concentration (0.1% to 10%) in the exhaust gas, and the gas-liquid ratio (G / L) ranges from 15 to 150:1.

[0048] The core reaction mechanism inside the reactor of scrubbing tower 3 is as follows:

[0049] Main reaction: SiH4 + 2NaOH → Na2SiO3 + 2H2↑

[0050] Side reaction: Na₂SiO₃ + H₂O → SiO₂·nH₂O + 2NaOH (accelerated by high temperature)

[0051] Therefore, the use of this invention can control the reaction temperature to ≤25~75℃, thereby reducing the formation of SiO2·nH2O colloid.

[0052] In one embodiment, at 1000 Nm 3 The results of the / h exhaust gas verification implementation are as follows:

[0053] Processing gas volume:

[0054] 1000Nm 3 / h, silane concentration 0.8%, H2 content 15%;

[0055] Operating parameters:

[0056] NaOH circulation rate 15m 3 / h, waste alkali external delivery rate 0.5m 3 / h, clean water replenishment 0.3m 3 / h; pressure drop of packing layer ≤300Pa / m, system resistance <5kPa;

[0057] Effect:

[0058] The silane removal rate is ≥99.9%, and the outlet H2 concentration is <0.5% LEL, effectively reducing the risk of fire at the top vent of the scrubbing tower.

[0059] This invention provides a concept and method for silane tail gas absorption in the FBR granular silicon production process. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of this invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. A device for silane tail gas absorption in the FBR granular silicon production process, characterized in that, include: A scrubbing tower (3) for receiving the silane tail gas; the middle part of the scrubbing tower (3) is provided with an alkali inlet and a water inlet for injecting alkali and water into the tower bottom respectively; the bottom of the scrubbing tower (3) is provided with an alkali outlet, which is fluidly connected to the spray device at the top of the scrubbing tower (3) through a heater (6); the alkali outlet also discharges alkali through a waste alkali regulating valve (13).

2. The device for silane tail gas absorption in the FBR granular silicon production process according to claim 1, characterized in that, The alkali inlet is fluidly connected to the alkali tank (1) through the alkali regulating valve (12), and the clean water inlet is connected to the externally input clean water through the clean water regulating valve (11).

3. The device for silane tail gas absorption in the FBR granular silicon production process according to claim 2, characterized in that, The rinsing tower (3) is equipped with a pH value and turbidity sensor (8) in the tower bottom, and is electrically connected to the waste alkali regulating valve (13) and the clean water regulating valve (11).

4. The device for silane tail gas absorption in the FBR granular silicon production process according to claim 3, characterized in that, The alkali outlet is fluidly connected to the waste alkali regulating valve (13) via a filter (4) and a corrosion-resistant pump (5).

5. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 4, characterized in that, The alkali outlet is fluidly connected to the input end of the heater (6) through a filter (4), a corrosion-resistant pump (5), and a heater valve; the output end of the heater (6) is fluidly connected to the spraying device through a spray pipe valve.

6. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 5, characterized in that, The exhaust gas inlet of the scrubbing tower (3) is equipped with a silane concentration detector (7), which is electrically connected to the valve of the spray pipe.

7. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 6, characterized in that, The scrubbing tower (3) is provided with a packing layer (9), which is located between the spraying device and the tail gas inlet, and is used for the tail gas to react with the alkaline solution.

8. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 7, characterized in that, A nitrogen pipe is provided at the exhaust gas inlet through a nitrogen valve, and a hydrogen concentration sensor (10) is provided at the spray device. The hydrogen concentration sensor (10) is electrically connected to the nitrogen valve.

9. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 8, characterized in that, The alkali tank (1) is used to store alkali solution and outputs alkali solution to the outside through the alkali pump (2) to form a self-circulation.

10. The apparatus for silane tail gas absorption in the FBR granular silicon production process according to claim 9, characterized in that, The packing layer (9) is configured as multiple segments, and its structure is one or more combinations of plate structure, structured packing or random packing, and the material is metal, non-metal or polymeric biopolymer material.

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