A dynamic control method for a feed of trichlorosilane synthesis

Abstract

The application discloses a kind of feed dynamic regulation methods of synthesizing trichlorosilane, through multispectral synergistic detection, through the accurate calculation of key parameters such as hydroxyl inhibition factor, amorphous phase activity gain and metal impurity inhibition factor, the activity condition of silicon powder in fluidized bed can be accurately and real-time reflected, the technical bottleneck that silicon powder activity cannot be monitored on line is broken through, and then in industrial production, for the proportion of fluidized bed feed etc. Real-time regulation provides control basis.Through feed dynamic regulation mechanism, silicon powder feed rate, H2 / SiCl4 ratio and catalyst addition amount can be optimized in real time, ensure that silicon powder is always in high activity state, promote the reaction to proceed, improve trichlorosilane yield and purity, solve the problem that traditional fixed regulation mode and silicon powder dynamic activity do not match, and then improve regulation accuracy.

Description

Technical Field

[0001] This invention relates to the field of trichlorosilane synthesis, and more specifically to a method for dynamic control of feed for the synthesis of trichlorosilane. Background Technology

[0002] Polycrystalline silicon is a core material for photovoltaic power generation and semiconductor chips, and its high-purity preparation is crucial in advanced manufacturing. In the mainstream modified Siemens process, silicon powder, as the core raw material for synthesizing trichlorosilane (SiHCl3), an important intermediate, participates in the chemical reaction Si + 3SiCl4 + 2H2 → 4SiHCl3. The reaction efficiency of this step directly affects the yield and energy consumption of subsequent high-purity silicon, while the activity of silicon powder has a significant impact on reaction efficiency and product purity.

[0003] As the reaction proceeds, the activity of silicon powder changes dynamically, and the activity also varies between different manufacturers and batches. However, current feeding methods do not take into account the dynamic characteristics of silicon powder, but instead adopt a fixed control mode. This lack of dynamic adjustment based on the real-time activity of the silicon powder results in the following main problems: because online real-time monitoring of silicon powder activity is currently impossible, real-time adjustment of process parameters is not possible. The fixed control mode leads to insufficient precision in control, failing to ensure that the silicon powder activity remains at a consistently high value, which in turn affects the conversion efficiency of the fluidized bed and increases energy consumption. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a method for dynamic control of feed in the synthesis of trichlorosilane.

[0005] This invention is implemented by the following technical solution:

[0006] A method for dynamic control of feed in the synthesis of trichlorosilane includes the following steps:

[0007] (1) Collaborative detection: During the operation of the fluidized bed, multiple spectral detectors are used to monitor the characteristic parameters;

[0008] (2) Real-time calculation of silicon powder activity: The real-time activity index of silicon powder in the fluidized bed is calculated using the characteristic parameters monitored in step (1) of the collaborative detection according to the silicon powder activity calculation method;

[0009] (3) Dynamic control of feed: Based on the real-time activity index of silicon powder in the fluidized bed calculated in step (2) real-time silicon powder activity calculation. The feed parameters entering the fluidized bed are dynamically controlled according to the feed dynamic control mechanism.

[0010] Furthermore, in step (1) of the collaborative detection, multiple spectroscopic detectors include an infrared detector, an in-situ Raman spectroscopic detector, and an ultraviolet-visible detector installed in the conical section of the fluidized bed reactor; the characteristic parameters include those at 3650 cm⁻¹. -1 Surface hydroxyl absorbance A 3650 At 600cm -1 Absorbance A of the Si-Cl bond at the location 600 At 480cm -1 Peak intensity I of the amorphous silicon phase at the location 480 At 520cm -1 Peak intensity I of the crystal at that location 520 And the absorbance of surface metallic impurities.

[0011] Furthermore, the absorbance of surface metallic impurities includes the absorbance of aluminum, a (Al).

[0012] Furthermore, the absorbance of surface metallic impurities also includes the absorbance of iron, a (Fe).

[0013] Furthermore, in step (2) real-time calculation of silicon powder activity, the silicon powder activity calculation method includes the following steps:

[0014] (21) Calculate the intermediate parameters based on the feature parameters detected in the collaborative detection in step (1):

[0015] The formula for converting parameters for calculating the hydroxyl inhibitor X1 is as follows:

[0016]

[0017] The parameter conversion formula for calculating the amorphous phase activity gain X2 is as follows:

[0018]

[0019] The formula for calculating the parameter conversion of the metal impurity inhibition factor X3 is as follows:

[0020]

[0021] (22) Calculate the real-time activity index of silicon powder in the fluidized bed using intermediate parameters:

[0022]

[0023] Where k is the hydroxyl inhibition coefficient, with a value of 1.2.

[0024] Furthermore, step (1) collaborative detection also includes monitoring the inlet and outlet pressure difference of the fluidized bed using a differential pressure sensor; in step (3) dynamic feed control, the dynamic feed control mechanism includes:

[0025] when If the concentration is ≤60%, then the machine should be shut down for maintenance and the dead ash should be removed.

[0026] When 60% < When the pressure difference is ≤80%, further determine whether the fluidized bed pressure difference is normal: if the fluidized bed pressure difference is <0.1MPa, increase the silicon powder feed rate by 10%-20% based on the current feed rate; if the fluidized bed pressure difference is >0.16MPa, first stop adding silicon powder; if the fluidized bed pressure difference is still >0.16MPa after 30 minutes, then stop the machine for maintenance.

[0027] when When the rate is greater than 80%, no special adjustments will be made to production to maintain stable operation.

[0028] Furthermore, step (1) collaborative detection also includes monitoring the TCS concentration using a mass spectrometer gas analyzer; in step (3) dynamic feed control, the dynamic feed control mechanism includes:

[0029] When the TCS concentration detected by the mass spectrometer gas analyzer is ≤22%, the H2 / SiCl4 molar ratio is increased from (1.5-2):1 to (1.6-2.3):1, and the amount of copper-based catalyst added is adjusted to 1‰ of the amount of silicon powder added.

[0030] No adjustment is made when the TCS concentration detected by the mass spectrometer gas analyzer is >22%.

[0031] Furthermore, the silicon powder particle size entering the fluidized bed is 0.125mm-0.6mm.

[0032] Advantages of this invention:

[0033] This invention utilizes multispectral synergistic detection to accurately and in real-time reflect the activity status of silicon powder in a fluidized bed through precise calculation of key parameters such as hydroxyl inhibitory factor, amorphous phase activity gain, and metal impurity inhibitory factor. This overcomes the technical bottleneck of the inability to monitor silicon powder activity online, providing a basis for real-time control of fluidized bed feed ratios in industrial production. Through a dynamic feed control mechanism, the silicon powder feed rate, H2 / SiCl4 ratio, and catalyst addition can be optimized in real-time, ensuring that the silicon powder remains in a highly active state, promoting the forward reaction, and improving the yield and purity of trichlorosilane. This solves the problem of mismatch between traditional fixed control modes and the dynamic activity of silicon powder, thereby improving control precision and avoiding low reaction efficiency and increased energy consumption due to insufficient silicon powder activity. Simultaneously, precise control reduces raw material waste (such as excess silicon powder or hydrogen), lowering production costs. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1:

[0036] A method for dynamic control of feed in the synthesis of trichlorosilane includes the following steps:

[0037] (1) Synergistic detection: During the operation of the fluidized bed, infrared detectors, in-situ Raman spectroscopy detectors, and ultraviolet-visible detectors installed in the conical section of the fluidized bed reactor are used to detect the temperature at 3650 cm⁻¹. -1 Surface hydroxyl absorbance A 3650 At 600cm -1 Absorbance A of the Si-Cl bond at the location 600 At 480cm -1 Peak intensity I of the amorphous silicon phase at the location 480 At 520cm -1 Peak intensity I of the crystal at that location 520 Simultaneous detection of absorbance a (Al) of aluminum and absorbance a (Fe) of iron was also performed. At the same time, differential pressure was monitored by differential pressure sensors installed in the inlet and outlet pipes of the fluidized bed, and TCS concentration was monitored by mass spectrometry gas analyzer.

[0038] (2) Real-time calculation of silicon powder activity, specifically including the following steps:

[0039] (21) Calculate the intermediate parameters based on the feature parameters detected in the collaborative detection in step (1):

[0040] The formula for converting parameters for calculating the hydroxyl inhibitor X1 is as follows:

[0041]

[0042] The parameter conversion formula for calculating the amorphous phase activity gain X2 is as follows:

[0043]

[0044] The formula for calculating the parameter conversion of the metal impurity inhibition factor X3 is as follows:

[0045]

[0046] (22) Calculate the real-time activity index of silicon powder in the fluidized bed using intermediate parameters:

[0047]

[0048] Wherein, k is the hydroxyl inhibition coefficient, with a value of 1.2 (determined through extensive experimental fitting, used to correct the nonlinear effect of hydroxyl groups on activity).

[0049] (3) Dynamic control of feed: Based on the real-time activity index of silicon powder in the fluidized bed calculated in step (2) real-time silicon powder activity calculation. The feed parameters entering the fluidized bed are dynamically controlled according to the feed dynamic control mechanism; the specific feed dynamic control mechanism includes:

[0050] when If the concentration is ≤60%, then the machine should be shut down for maintenance and the dead ash (i.e., deactivated material) should be removed.

[0051] When 60% < When the pressure difference is ≤80%, further determine whether the fluidized bed pressure difference is normal: if the fluidized bed pressure difference is <0.1MPa, increase the silicon powder feed rate by 10%-20% based on the current feed rate; if the fluidized bed pressure difference is >0.16MPa, first stop adding silicon powder; if the fluidized bed pressure difference is still >0.16MPa after 30 minutes, then stop the machine for maintenance.

[0052] when When the rate is greater than 80%, no special adjustments will be made to production to maintain stable operation.

[0053] When the TCS concentration detected by the mass spectrometer gas analyzer is ≤22%, the H2 / SiCl4 molar ratio is increased from (1.5-2):1 to (1.6-2.3):1, and the amount of copper-based catalyst added is adjusted to 1‰ of the amount of silicon powder added.

[0054] No adjustment is made when the TCS concentration detected by the mass spectrometer gas analyzer is >22%.

[0055] A TCS concentration ≤22% indicates a low silicon tetrachloride conversion rate, meaning the reversible reaction SiCl4 + Si + 2H2 = 4SiHCl3 is not progressing sufficiently to the right, and the silicon tetrachloride concentration in the fluidized bed is high. According to Le Chatelier's principle, increasing the reactant concentration or decreasing the product concentration should shift the equilibrium towards the forward reaction. Therefore, increasing the H2 / SiCl4 molar ratio increases the H2 concentration, applying a "reactant increase" pressure to the equilibrium system. To counteract this pressure, the equilibrium shifts to the right, thereby increasing the SiCl4 conversion rate and the apparent activity of the silicon powder. Simultaneously, as the reaction proceeds, the silicon powder is consumed, reducing reactivity; increasing the amount of silicon powder added can improve the conversion rate.

[0056] In this embodiment, the silicon powder particle size entering the fluidized bed is 0.125mm-0.6mm. Silicon powder within this particle size range can ensure good fluidization effect and avoid poor fluidization and insufficient reaction due to excessively large silicon powder particles. It can also prevent silicon powder particles that are too small from not participating in fluidization and escaping directly, causing system blockage after entering the system. At the same time, it avoids affecting the accuracy of the real-time activity index calculation of silicon powder due to the failure to calculate the particle size value of escaped silicon powder.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for dynamic control of feed in the synthesis of trichlorosilane, characterized in that, Includes the following steps: (1) Collaborative detection: During the operation of the fluidized bed, multiple spectral detectors are used to monitor the characteristic parameters; (2) Real-time calculation of silicon powder activity: The real-time activity index of silicon powder in the fluidized bed is calculated using the characteristic parameters monitored in step (1) of the collaborative detection according to the silicon powder activity calculation method; (3) Dynamic control of feed: Based on the real-time activity index of silicon powder in the fluidized bed calculated in step (2) real-time silicon powder activity calculation. The feed parameters entering the fluidized bed are dynamically controlled according to the feed dynamic control mechanism; In the collaborative detection of step (1), multiple spectral detectors include an infrared detector, an in-situ Raman spectroscopy detector, and an ultraviolet-visible detector set in the conical section of the fluidized bed reactor; The characteristic parameters include 3650cm -1 Surface hydroxyl absorbance A 3650 At 600cm -1 Absorbance A of the Si-Cl bond at the location 600 At 480cm -1 Peak intensity I of the amorphous silicon phase at the location 480 At 520cm -1 Peak intensity I of the crystal at that location 520 And the absorbance of surface metallic impurities; The absorbance of surface metallic impurities includes the absorbance a (Al) of aluminum, and also includes the absorbance a (Fe) of iron. In step (2), the real-time calculation of silicon powder activity includes the following steps: (21) Calculate the intermediate parameters based on the feature parameters detected in the collaborative detection in step (1): The formula for converting parameters for calculating the hydroxyl inhibitor X1 is as follows: The parameter conversion formula for calculating the amorphous phase activity gain X2 is as follows: The formula for calculating the parameter conversion of the metal impurity inhibition factor X3 is as follows: (22) Calculate the real-time activity index of silicon powder in the fluidized bed using intermediate parameters: Where k is the hydroxyl inhibition coefficient, with a value of 1.

2.

2. The method for dynamic control of feed in the synthesis of trichlorosilane according to claim 1, characterized in that, The collaborative detection in step (1) also includes monitoring the pressure difference between the inlet and outlet of the fluidized bed using a differential pressure sensor; In step (3) dynamic control of feed, the dynamic control mechanism of feed includes: when If the concentration is ≤60%, then the machine should be shut down for maintenance and the dead ash should be removed. When 60% < When the pressure difference is ≤80%, further determine whether the fluidized bed pressure difference is normal: if the fluidized bed pressure difference is <0.1MPa, increase the silicon powder feed rate by 10%-20% based on the current feed rate; if the fluidized bed pressure difference is >0.16MPa, first stop adding silicon powder; if the fluidized bed pressure difference is still >0.16MPa after 30 minutes, then stop the machine for maintenance. when When the rate is greater than 80%, no special adjustments will be made to production to maintain stable operation.

3. The method for dynamic control of feed in the synthesis of trichlorosilane according to claim 1, characterized in that, The collaborative detection step (1) also includes monitoring the TCS concentration using a mass spectrometer gas analyzer; the dynamic feed control mechanism in step (3) includes: When the TCS concentration detected by the mass spectrometer gas analyzer is ≤22%, the H2 / SiCl4 molar ratio is increased from (1.5-2):1 to (1.6-2.3):1, and the amount of copper-based catalyst added is adjusted to 1‰ of the amount of silicon powder added. No adjustment is made when the TCS concentration detected by the mass spectrometer gas analyzer is >22%.

4. The method for dynamic control of feed in the synthesis of trichlorosilane according to claim 1, characterized in that, The silicon powder entering the fluidized bed has a particle size of 0.125 mm to 0.6 mm.

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