A preparation method of trichlorosilane

Abstract

The present invention provides a method for preparing trichlorosilane, comprising the following steps: continuously adding hydrogen chloride gas and silicon powder to a fluidized bed reactor for reaction, wherein the flow rate of hydrogen chloride gas is within the range of 400 to 750 standard cubic meters per hour, and the feed rate of silicon powder is within the range of 19 to 290 kg / h, to obtain a set of hydrogen chloride gas flow rate and silicon powder feed rate that stabilize the bed pressure difference, and to maintain the flow rate of hydrogen chloride gas and the feed rate of silicon powder unchanged during the reaction process; regulating the cooling water flow rate during the reaction process so that the reaction temperature is maintained between 340 and 350°C, and maintaining the cooling water flow rate unchanged during the reaction process after the regulation is completed. The preparation method provided in the present invention can produce trichlorosilane at a constant temperature and a constant bed pressure difference, and can effectively reduce by-products and improve the conversion rate of trichlorosilane compared to the production method of centralized feeding and intermittent cooling used in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of synthesizing trichlorosilane, and in particular to a method for preparing trichlorosilane. Background Art

[0002] The process of synthesizing trichlorosilane using silicon powder and hydrogen chloride is as follows: silicon powder enters the fluidized bed from the top feed port of the fluidized bed reactor, and hydrogen chloride enters the fluidized bed from the air inlet of the lower head of the fluidized bed reactor. The two react inside the fluidized bed reactor to synthesize trichlorosilane. The reaction temperature during the reaction process has a great influence on the generated product. The relationship between the reaction principle and the reaction temperature is as follows:

[0003] Main reaction: Si+3HCl→(340℃-350℃)SiHCl3+H2

[0004] Si+4HCl→(>350℃)SiCl4+2H2

[0005] Side reaction: Si+2HCl→(<280℃)SiH2Cl3

[0006] nSi+(2n+2)HCl→Si n Cl 2n+2 +(n+1)H2.

[0007] As can be seen from the above reaction equation, to reduce the production of byproducts, the reaction temperature must be maintained between 340°C and 350°C. In the prior art, jacket water is commonly used to cool the fluidized bed reactor. Specifically, when the reaction temperature inside the fluidized bed reactor is detected to be too high, jacket water is added to cool it down to a certain value. Then, after a period of reaction, if the temperature again becomes too high, jacket water is added again to cool it down to a certain value. This cooling method exhibits hysteresis, and the temperature fluctuates significantly during the reaction, resulting in a high number of byproducts. Furthermore, a centralized feeding method is also commonly used in the prior art. 300-500 kg of silicon powder is placed in a container and heated for 4-5 hours. Based on production conditions, centralized feeding is then added. When the silicon powder is consumed to a certain extent, new silicon powder is added to replenish the raw material. The temperature of the newly added silicon powder also affects the reaction temperature inside the fluidized bed reactor. Therefore, the current greatest difficulty in producing trichlorosilane using the hydrosilicon chlorination process is achieving a constant temperature of 350°C.

[0008] When synthesizing trichlorosilane using a fluidized bed reactor, in addition to maintaining a stable reaction temperature between 340°C and 350°C, the bed thickness of the fluidized bed is another important factor affecting the efficiency of trichlorosilane synthesis. Excessively thick or thin bed thicknesses can lead to incomplete reaction and low production efficiency. Therefore, maintaining an appropriate bed thickness is crucial when producing trichlorosilane. Summary of the Invention

[0009] In view of this, the present invention provides a method for preparing trichlorosilane. The preparation method of the present invention can ensure that trichlorosilane is synthesized at a stable bed thickness and a constant reaction temperature, thereby improving the conversion rate of trichlorosilane.

[0010] In order to solve the technical problems raised in the background technology, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing trichlorosilane, wherein the preparation method comprises:

[0012] Hydrogen chloride gas and silicon powder are continuously added to a fluidized bed reactor for reaction, wherein the flow rate of the hydrogen chloride gas is regulated within a range of 400 standard cubic meters per hour to 750 standard cubic meters per hour, and the feed rate of the silicon powder is regulated within a range of 190 kg / hour to 290 kg / hour to obtain a set of corresponding hydrogen chloride gas flow rates and silicon powder feed rates, so that the bed pressure difference of the fluidized bed reactor is maintained at any value between 45 kPa and 55 kPa, and the bed pressure difference fluctuates by no more than 1 kPa during the reaction; after the regulation is completed, the flow rate of the hydrogen chloride gas and the feed rate of the silicon powder are maintained unchanged during the reaction;

[0013] The outer wall of the fluidized bed reactor is provided with a jacket, and cooling water is continuously introduced into the jacket for cooling during the reaction process. The flow rate of the cooling water is regulated so that the reaction temperature inside the fluidized bed is maintained between 340°C and 350°C. After the regulation is completed, the flow rate of the cooling water is kept unchanged during the reaction process.

[0014] Furthermore, regulating the flow rate of the hydrogen chloride gas and the feed amount of the silicon powder includes:

[0015] When the flow rate of the hydrogen chloride gas is 400 standard cubic meters / h to 420 standard cubic meters / h, the feed rate of the silicon powder is 190 kg / h to 200 kg / h, and the corresponding bed pressure difference is maintained between 45 kPa and 48 kPa; or

[0016] When the flow rate of the hydrogen chloride gas is 500 standard cubic meters / h to 530 standard cubic meters / h, the feed rate of the silicon powder is 210 kg / h to 220 kg / h, and the corresponding bed pressure difference is maintained between 48 kPa and 50 kPa; or

[0017] When the flow rate of the hydrogen chloride gas is 600 standard cubic meters / h to 635 standard cubic meters / h, the feed rate of the silicon powder is 250 kg / h to 260 kg / h, and the corresponding bed pressure difference is maintained between 50 kPa and 52 kPa; or

[0018] When the flow rate of the hydrogen chloride gas is 700 standard cubic meters / h to 750 standard cubic meters / h, the feed rate of the silicon powder is 280 kg / h to 290 kg / h, and the corresponding bed pressure difference is maintained between 52 KPa and 55 KPa.

[0019] Furthermore, before the reaction, heated hydrogen is introduced into the fluidized bed reactor to make the temperature inside the fluidized bed reactor reach above 280° C., and then the hydrogen chloride gas and the silicon powder are introduced to react.

[0020] Furthermore, during the reaction process: if the reaction temperature of the fluidized bed reactor becomes abnormal, when the reaction temperature is lower than 330° C., it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reaction is shut down; and / or if the bed pressure difference of the fluidized bed reactor becomes abnormal, when the bed pressure difference of the fluidized bed reactor is lower than 45 kPa, higher than 55 kPa, or the bed pressure difference fluctuates by more than 1 kPa, it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reaction is shut down.

[0021] Furthermore, the method utilizes a trichlorosilane synthesis system;

[0022] The trichlorosilane synthesis system comprises: a fluidized bed reactor, a silicon powder feeding tank, a silicon powder regulating valve, a hydrogen chloride feeding tank, a hydrogen chloride gas regulating valve, a temperature measuring device, a first pressure gauge, a second pressure gauge, a jacket water tank and a cooling water regulating valve;

[0023] The fluidized bed reactor comprises: a fluidized bed shell, a reaction section located in the middle of the fluidized bed shell, a hydrogen chloride gas inlet and a silicon powder inlet provided on the fluidized bed shell and connected to the reaction section, and a jacket provided on the outer wall of the fluidized bed shell;

[0024] The temperature measuring device is arranged inside the reaction section for measuring the reaction temperature of the reaction section; the first pressure gauge and the second pressure gauge are respectively installed at the upper and lower ends of the fluidized bed reactor for measuring the bed pressure difference of the fluidized bed reactor;

[0025] The silicon powder feeding tank is connected to the silicon powder regulating valve and communicates with the silicon powder inlet through a pipeline; the hydrogen chloride feeding tank is connected to the hydrogen chloride gas regulating valve and communicates with the hydrogen chloride gas inlet through a pipeline; the jacket water tank contains cooling water, and the jacket water tank is connected to the cooling water regulating valve and communicates with the jacket on the outer wall of the fluidized bed shell through a pipeline.

[0026] Furthermore, the hydrogen chloride gas inlet is arranged at the bottom end of the reaction section, and the silicon powder inlet is arranged at the top end of the reaction section.

[0027] Furthermore, the fluidized bed reactor also includes: a lower cone connected to the lower end of the reaction section, and an upper head connected to the upper end of the reaction section; the reaction section includes a main reaction section and a secondary reaction section, wherein the main reaction section is the lower half close to the lower cone, and the secondary reaction section is the upper half close to the upper head; the temperature measuring device includes a first temperature meter and a second temperature meter, the first temperature meter is arranged at the upper end of the main reaction section, and the second temperature meter is arranged at the lower end of the main reactor.

[0028] Furthermore, a method for preparing trichlorosilane using the trichlorosilane synthesis system is as follows: hydrogen chloride gas in the hydrogen chloride feeding tank is continuously fed into the fluidized bed reaction section through the hydrogen chloride gas inlet via a pipeline; simultaneously, silicon powder in the silicon powder feeding tank is continuously fed into the fluidized bed reaction section through the silicon powder inlet via a pipeline; the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor, and according to the test results, the flow rate of the hydrogen chloride gas is 400 standard cubic meters / h to 750 standard cubic meters / h and the feed rate of the silicon powder is 190 kg / h to 290 kg / h to obtain a set of corresponding hydrogen chloride gas flow rates and silicon powder feed rates, so that the bed pressure difference of the fluidized bed reactor reaches any value between 45 kPa and 55 kPa, and the bed pressure difference fluctuates by no more than 1 kPa during the reaction; after the control is completed, the flow rate of the hydrogen chloride gas and the feed rate of the silicon powder are maintained unchanged during the reaction;

[0029] The reaction temperature of the reaction section is tested by the temperature measuring device, and cooling water is continuously passed into the jacket using the jacket water tank for cooling according to the temperature measurement result. The flow rate of the cooling water is regulated so that the reaction temperature is maintained between 340°C and 350°C. After the regulation is completed, the flow rate of the cooling water is kept unchanged during the reaction process.

[0030] Furthermore, the trichlorosilane synthesis system also includes a controller, which is electrically connected to the temperature measuring device, the silicon powder regulating valve, the hydrogen chloride gas regulating valve, the first pressure gauge, the second pressure gauge and the cooling water regulating valve.

[0031] Furthermore, at the start of the reaction, the temperature measuring device measures the temperature and sends a temperature signal to the controller. When the controller obtains the temperature signal indicating that the reaction temperature reaches 350°C, it controls the opening of the cooling water regulating valve until the reaction temperature is maintained between 340°C and 350°C during the reaction, and maintains the cooling water regulating valve unchanged during the reaction.

[0032] During the reaction process, if the controller obtains a temperature signal indicating that the reaction temperature is lower than 330° C., the openings of the silicon powder regulating valve and the hydrogen chloride gas regulating valve are controlled to gradually decrease until they are closed; and / or the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor and provide a bed pressure difference signal to the controller. When the controller obtains any one of the bed pressure difference signals of lower than 45 kPa, higher than 55 kPa, and the bed pressure difference fluctuates by more than 1 kPa, the controller controls the openings of the silicon powder regulating valve and the hydrogen chloride gas regulating valve to gradually decrease until they are closed.

[0033] The beneficial effects of the above technical solution of the present invention are as follows:

[0034] The present invention provides a method for preparing trichlorosilane, which realizes the production of trichlorosilane at a constant temperature and a constant bed pressure difference (i.e., bed thickness). In the present invention, a suitable raw material feed amount and feed rate are obtained through debugging, and this raw material feed amount and feed rate are used for continuous feeding, thereby achieving the purpose of stabilizing the bed pressure difference and stabilizing the heat of the reaction system. At this time, by debugging a suitable cooling water flow rate to take away excess heat, it is possible to achieve the production of trichlorosilane at a constant temperature and a constant bed pressure difference. Compared with the production method of centralized feeding and intermittent cooling used in the prior art, the method for preparing trichlorosilane provided in the present invention can effectively reduce by-products and improve the conversion rate of trichlorosilane. It has been verified that the preparation method of the present invention can increase the conversion rate of trichlorosilane from 75% to 78% in the prior art to 82% to 88%. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of the trichlorosilane synthesis system. Description of the drawings:

[0037] Fluidized bed reactor 1, silicon powder feeding tank 2, silicon powder buffer tank 3, silicon powder regulating valve 4, hydrogen chloride feeding tank 5, hydrogen chloride gas regulating valve 6, temperature measuring device 7, jacket water tank 8, cooling water regulating valve 9, controller 10. DETAILED DESCRIPTION

[0038] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than for limiting the present invention.

[0039] In a first aspect, the present invention provides a method for preparing trichlorosilane, wherein the preparation method comprises:

[0040] Hydrogen chloride gas and silicon powder are continuously added to a fluidized bed reactor 1 for reaction, wherein the flow rate of the hydrogen chloride gas is regulated within a range of 400 standard cubic meters per hour (SCM) to 750 SCM per hour (SCM), and the feed rate of the silicon powder is regulated within a range of 190 kg / h to 290 kg / h. A set of corresponding hydrogen chloride gas flow rates and silicon powder feed rates are obtained, such that the bed pressure difference of the fluidized bed reactor 1 is maintained at any value between 45 kPa and 55 kPa, and the bed pressure difference fluctuates by no more than 1 kPa during the reaction. After the regulation is completed, the flow rate of the hydrogen chloride gas and the feed rate of the silicon powder are maintained unchanged during the reaction. The outer wall of the fluidized bed reactor 1 is provided with a jacket, and cooling water is continuously introduced into the jacket for cooling during the reaction. The flow rate of the cooling water is regulated so that the reaction temperature inside the fluidized bed is maintained between 340° C. and 350° C., and the flow rate of the cooling water is maintained unchanged during the reaction.

[0041] The present invention provides a method for producing trichlorosilane at a constant temperature and a constant bed pressure difference (i.e., bed thickness). Specifically, the preparation method and principle of the present invention are as follows: First, in the present invention, hydrogen chloride gas and silicon powder are continuously introduced into the fluidized bed reactor 1. The bed pressure difference is determined by the flow rate of hydrogen chloride gas and the feed amount of silicon powder. That is, if the flow rate of hydrogen chloride gas and the feed amount of silicon powder are controlled to be continuous and stable, the bed pressure difference can be kept stable. The method provided by the present invention is to regulate the flow rate of the hydrogen chloride gas between 400 standard cubic meters / h and 750 standard cubic meters / h, and to regulate the feed amount of the silicon powder between 190kg / h and 290kg / h. It is required to obtain a set of mutually corresponding hydrogen chloride gas flow rates and silicon powder feed amounts, so that the bed pressure difference of the fluidized bed reactor 1 is an arbitrary value between 45KPa and 55KPa, and the bed pressure difference fluctuates by no more than 1KPa during the reaction. Once the corresponding set of hydrogen chloride gas flow rates and silicon powder feed rates are determined through debugging, the reaction is then conducted using that set of feed rates. As long as the synthesis reaction does not malfunction, the fixed feed rates, bed pressure differential, and reaction rate can be maintained throughout the entire reaction process. During the reaction, since the silicon powder feed rate is fixed, the cooling energy introduced into the fluidized bed by the silicon powder is also fixed. Since the reaction rate is also fixed, the heat of reaction is also fixed. Furthermore, since a relatively stable reaction temperature (340°C to 350°C) must be maintained, cooling water is required to continuously and steadily remove some heat. This heat is also fixed. Assuming the cooling water temperature is constant, debugging can determine a cooling water flow rate that maintains a stable reaction temperature within the fluidized bed between 340°C and 350°C. In summary, the present invention obtains a suitable raw material feed amount and feed rate, and uses this raw material feed amount and feed rate for continuous feeding, so as to achieve the purpose of stabilizing the bed pressure difference and stabilizing the heat of the reaction system. At this time, by adjusting a suitable cooling water flow rate to take away excess heat, it is possible to produce trichlorosilane at a constant temperature and a constant bed pressure difference. The method for preparing trichlorosilane provided in the present invention can effectively reduce by-products and improve the conversion rate of trichlorosilane compared to the production method of centralized feeding and intermittent cooling used in the prior art. It has been verified that the preparation method of the present invention can increase the conversion rate of trichlorosilane from 75% to 78% in the prior art to 82% to 88%.

[0042] The preparation method provided in the present invention takes into account the influence of external media on the fluidized bed during the production of trichlorosilane, the cooling water temperature drop, and the cooling capacity carried by the added silicon powder. The temperature inside the fluidized bed is predicted, and the reaction temperature is balanced by the cooling water flow rate and the silicon powder feed rate. During the balancing process, the adjustment of the cooling water flow rate and the silicon powder consumption are combined to obtain a stable bed pressure difference and reaction temperature. The balanced two-way regulation realizes the continuous, stable, and constant temperature production of trichlorosilane.

[0043] Furthermore, the inventors of the present invention debugged and obtained some hydrogen chloride gas flow rates and corresponding silicon powder feed rates, including: when the hydrogen chloride gas flow rate is 400 standard cubic meters / h to 420 standard cubic meters / h, the silicon powder feed rate is 190kg / h to 200kg / h, and the corresponding bed pressure difference is maintained between 45KPa and 48KPa; or when the hydrogen chloride gas flow rate is 500 standard cubic meters / h to 530 standard cubic meters / h, the silicon powder feed rate is 210kg / h to 220kg / h, and the corresponding bed pressure difference is maintained between 45KPa and 48KPa. The layer pressure difference is maintained between 48KPa and 50KPa; or when the flow rate of the hydrogen chloride gas is 600 standard cubic meters / h to 635 standard cubic meters / h, the feed rate of the silicon powder is 250kg / h to 260kg / h, and the corresponding bed pressure difference is maintained between 50KPa and 52KPa; or when the flow rate of the hydrogen chloride gas is 700 standard cubic meters / h to 750 standard cubic meters / h, the feed rate of the silicon powder is 280kg / h to 290kg / h, and the corresponding bed pressure difference is maintained between 52KPa and 55KPa. Specifically, the flow rate of hydrogen chloride gas can be set to 400 standard cubic meters / h, and the feed rate of silicon powder can be set to 190 kg / h; or the flow rate of hydrogen chloride gas can be set to 500 standard cubic meters / h, and the feed rate of silicon powder can be set to 210 kg / h; or the flow rate of hydrogen chloride gas can be set to 600 standard cubic meters / h, and the feed rate of silicon powder can be set to 250 kg / h; or the flow rate of hydrogen chloride gas can be set to 700 standard cubic meters / h, and the feed rate of silicon powder can be set to 280 kg / h.

[0044] According to some embodiments of the present invention, heated hydrogen is introduced into the fluidized bed reactor 1 before the reaction so that the temperature inside the fluidized bed reactor 1 reaches above 280° C., and then the hydrogen chloride gas and the silicon powder are introduced to react.

[0045] According to some embodiments of the present invention, during the reaction process, if the reaction temperature of the fluidized bed reactor 1 becomes abnormal, when the reaction temperature is lower than 330°C, it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reaction is shut down; if the bed pressure difference of the fluidized bed reactor 1 becomes abnormal, when the bed pressure difference of the fluidized bed reactor 1 is lower than 45KPa, higher than 55KPa, or the bed pressure difference fluctuates by more than 1KPa, it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reaction is shut down.

[0046] It should be noted that during normal production, the method for preparing trichlorosilane provided herein should be able to maintain a stable reaction temperature between 340°C and 350°C, while maintaining a bed pressure differential between 45 kPa and 55 kPa, with the bed pressure differential fluctuating by no more than 1 kPa during the reaction. Therefore, if the reaction temperature falls below 330°C, the bed pressure differential of the fluidized bed reactor 1 falls below 45 kPa or exceeds 55 kPa, or the bed pressure differential fluctuates by more than 1 kPa, it indicates that an abnormality has occurred in the synthesis reaction, and in this case, the flow rate of hydrogen chloride gas and the silicon powder feed rate need to be gradually reduced until the reaction is shut down.

[0047] According to other embodiments of the present invention, the method for preparing trichlorosilane utilizes a trichlorosilane synthesis system, wherein the trichlorosilane synthesis system is as follows: Figure 1 shown.

[0048] Participate in the Figure 1 The trichlorosilane synthesis system includes: a fluidized bed reactor 1, a silicon powder feeding tank 2, a silicon powder regulating valve 4, a hydrogen chloride feeding tank 5, a hydrogen chloride gas regulating valve 6, a temperature measuring device 7, a first pressure gauge, a second pressure gauge, a jacket water tank 8 and a cooling water regulating valve 9;

[0049] In which, the fluidized bed reactor 1 includes: a fluidized bed shell, a reaction section located in the middle of the fluidized bed shell, a hydrogen chloride gas inlet and a silicon powder inlet arranged on the fluidized bed shell and connected to the reaction section, and a jacket arranged on the outer wall of the fluidized bed shell; the temperature measuring device 7 is arranged inside the reaction section for testing the reaction temperature of the reaction section; the first pressure gauge and the second pressure gauge are respectively installed at the upper and lower ends of the fluidized bed reactor 1 for testing the bed pressure difference of the fluidized bed reactor 1; the silicon powder feeding tank 2 is connected to the silicon powder regulating valve 4 and is connected to the silicon powder inlet through a pipeline; the hydrogen chloride feeding tank 5 is connected to the hydrogen chloride gas regulating valve 6 and is connected to the hydrogen chloride gas inlet through a pipeline; the jacket water tank 8 contains cooling water, the jacket water tank 8 is connected to the cooling water regulating valve 9, and is connected to the jacket on the outer wall of the fluidized bed shell through a pipeline.

[0050] According to some other embodiments of the present invention, the trichlorosilane synthesis system further includes: a silicon powder buffer tank 3, which is arranged below the silicon powder feeding tank 2, and the silicon powder first enters the silicon powder buffer tank 3 from the silicon powder feeding tank 2, and then enters the fluidized bed reactor 1.

[0051] According to other embodiments of the present invention, the hydrogen chloride gas inlet is located at the bottom of the reaction section, and the silicon powder inlet is located at the top of the reaction section. During the reaction, the silicon powder enters the reaction section from top to bottom, and the hydrogen chloride gas enters the reactor from bottom to top. Furthermore, when the silicon powder enters the reaction section, hydrogen chloride gas or hydrogen is blown into the reaction section. The amount of hydrogen chloride gas or hydrogen used is very small, generally 3 to 4 standard cubic meters per hour.

[0052] According to some other embodiments of the present invention, the fluidized bed reactor 1 further includes: a lower cone connected to the lower end of the reaction section, and an upper head connected to the upper end of the reaction section; the reaction section includes a main reaction section and a secondary reaction section, wherein the main reaction section is the lower half close to the lower cone, and the secondary reaction section is the upper half close to the upper head; the temperature measuring device 7 includes a first temperature detector and a second temperature detector, the first temperature detector is arranged at the upper end of the main reaction section, and the second temperature detector is arranged at the lower end of the main reactor. In the present invention, the temperatures of the upper and lower parts of the main reaction section are measured by the first temperature detector and the second temperature detector. During the reaction process, the temperature values measured by the first temperature detector and the second temperature detector should differ by within 5°C.

[0053] According to other embodiments of the present invention, the method for preparing trichlorosilane using the trichlorosilane synthesis system is:

[0054] The hydrogen chloride gas in the hydrogen chloride feeding tank 5 is continuously fed into the fluidized bed reaction section through the hydrogen chloride gas inlet via a pipeline; at the same time, the silicon powder in the silicon powder feeding tank 2 is continuously fed into the fluidized bed reaction section through the silicon powder inlet via a pipeline; the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor 1, and according to the test results, the flow rate of the hydrogen chloride gas is 400 standard cubic meters / h to 750 standard cubic meters / h and the feed rate of the silicon powder is 190 kg / h to 290 kg / h, thereby obtaining a set of corresponding flow rates of the hydrogen chloride gas and the feed rate of the silicon powder. The fluidized bed reactor 1 is provided with a material amount so that the bed pressure difference of the fluidized bed reactor 1 reaches any value between 45 kPa and 55 kPa, and the fluctuation of the bed pressure difference during the reaction does not exceed 1 kPa; after the regulation is completed, the flow rate of hydrogen chloride gas and the feed amount of silicon powder are kept unchanged during the reaction; the reaction temperature of the reaction section is tested by the temperature measuring device 7, and cooling water is continuously introduced into the jacket through the jacket water tank 8 according to the temperature measurement result, and the water flow of the cooling water is regulated so that the reaction temperature is maintained between 340° C. and 350° C., and the water flow of the cooling water is kept unchanged during the reaction.

[0055] Specifically, the method for preparing trichlorosilane using the trichlorosilane synthesis system can be as follows: the hydrogen chloride gas in the hydrogen chloride feeding tank 5 is continuously fed into the fluidized bed reaction section through the hydrogen chloride gas inlet via a pipeline; simultaneously, the silicon powder in the silicon powder feeding tank 2 is continuously fed into the fluidized bed reaction section through the silicon powder inlet via a pipeline; the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor 1, and according to the test results, the hydrogen chloride gas flow rate is 400 standard cubic meters / h to 750 standard cubic meters / h and the silicon powder feed rate is 190 kg / h to 290 kg / h, thereby achieving a hydrogen chloride gas flow rate of 400 standard cubic meters / h and a silicon powder feed rate of 190 kg / h, at which point the bed pressure difference is 47 kPa and fluctuates within 1 kPa. During the reaction, the hydrogen chloride gas flow rate is maintained at 400 standard cubic meters / h and the silicon powder feed rate is maintained at 190 kg / h. The reaction temperature of the reaction section is tested by the temperature measuring device 7. The temperature measured when the raw materials are just introduced will be lower. As the reaction starts, the temperature rises. When the reaction temperature is higher than 350°C, the flow rate of the cooling water is regulated so that the reaction temperature is maintained between 340°C and 350°C. Specifically, when the flow rate of hydrogen chloride gas is 400 standard cubic meters / h, the feed rate of silicon powder is 190kg / h, and the temperature of the feed silicon powder is 15°C, the flow rate of the cooling water is regulated to 3.6m 3 / h, the reaction temperature can be kept stable, that is, the system heat is stable, and the cooling water flow rate is kept at 3.6m 3 / h remains unchanged.

[0056] According to some other embodiments of the present invention, the trichlorosilane synthesis system further includes a controller 10, and the controller 10 is electrically connected to the temperature measuring device 7, the silicon powder regulating valve 4, the hydrogen chloride gas regulating valve 6, the first pressure gauge, the second pressure gauge and the cooling water regulating valve 9.

[0057] Furthermore, the trichlorosilane synthesis system also includes a controller 10, which can obtain temperature and bed pressure difference signals and control the openings of the silicon powder regulating valve 4, the hydrogen chloride gas regulating valve 6, and the cooling water regulating valve 9 to regulate the trichlorosilane synthesis system during the start and progress of the reaction.

[0058] According to other embodiments of the present invention, at the start of the reaction, the temperature measuring device 7 measures the temperature and sends a temperature signal to the controller 10. When the controller 10 obtains a temperature signal indicating that the reaction temperature reaches 350°C, it controls the opening of the cooling water regulating valve 9 until the reaction temperature is maintained between 340°C and 350°C during the reaction, and maintains the opening of the cooling water regulating valve 9 unchanged during the reaction. During the reaction, if the controller 10 obtains a temperature signal indicating that the reaction temperature is lower than 330°C, it controls the openings of the silicon powder regulating valve 4 and the hydrogen chloride gas regulating valve 6 to gradually decrease until they are closed.

[0059] At the same time, the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor 1 and provide a bed pressure difference signal to the controller 10. When the controller 10 obtains any one of the bed pressure difference signals, namely, the bed pressure difference is lower than 45 kPa, higher than 55 kPa, and the bed pressure difference fluctuates by more than 1 kPa, the opening of the silicon powder regulating valve 4 and the hydrogen chloride gas regulating valve 6 is controlled to gradually decrease until they are closed.

[0060] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the ordinary meaning understood by persons having ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0061] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing trichlorosilane, characterized in that: The preparation method is: Hydrogen chloride gas and silicon powder are continuously added to the fluidized bed reactor for reaction. During the reaction, the bed pressure difference fluctuates by no more than 1 kPa. After the regulation is completed, the flow rate of hydrogen chloride gas and the feed amount of silicon powder are kept constant during the reaction. The outer wall of the fluidized bed reactor is provided with a jacket, and cooling water is continuously passed into the jacket for cooling during the reaction process. The flow rate of the cooling water is regulated so that the reaction temperature inside the fluidized bed is maintained between 340° C. and 350° C. After the regulation is completed, the flow rate of the cooling water is maintained unchanged during the reaction process; During the reaction: If the reaction temperature of the fluidized bed reactor becomes abnormal, when the reaction temperature is lower than 330°C, it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reactor is shut down; and / or If the bed pressure difference of the fluidized bed reactor is abnormal, such as when the bed pressure difference of the fluidized bed reactor is lower than 45 kPa, higher than 55 kPa, or when the bed pressure difference fluctuates by more than 1 kPa, it is necessary to gradually reduce the flow rate of hydrogen chloride gas and the feed rate of silicon powder until the reactor is shut down; regulating the flow rate of the hydrogen chloride gas and the feed amount of the silicon powder; Regulating the flow rate of the hydrogen chloride gas and the feed amount of the silicon powder includes: When the flow rate of the hydrogen chloride gas is 400 standard cubic meters / h to 420 standard cubic meters / h, the feed rate of the silicon powder is 190 kg / h to 200 kg / h, and the corresponding bed pressure difference is maintained between 45 kPa and 48 kPa; or When the flow rate of the hydrogen chloride gas is 500 standard cubic meters / h to 530 standard cubic meters / h, the feed rate of the silicon powder is 210 kg / h to 220 kg / h, and the corresponding bed pressure difference is maintained between 48 kPa and 50 kPa; or When the flow rate of the hydrogen chloride gas is 600 standard cubic meters / h to 635 standard cubic meters / h, the feed rate of the silicon powder is 250 kg / h to 260 kg / h, and the corresponding bed pressure difference is maintained between 50 kPa and 52 kPa; or When the flow rate of the hydrogen chloride gas is 700 standard cubic meters / h to 750 standard cubic meters / h, the feed rate of the silicon powder is 280 kg / h to 290 kg / h, and the corresponding bed pressure difference is maintained between 52 KPa and 55 KPa.

2. The preparation method according to claim 1, characterized in that Before the reaction, heated hydrogen is introduced into the fluidized bed reactor to make the temperature inside the fluidized bed reactor reach above 280° C., and then the hydrogen chloride gas and the silicon powder are introduced to react.

3. The preparation method according to claim 1, characterized in that The method utilizes a trichlorosilane synthesis system; The trichlorosilane synthesis system comprises: a fluidized bed reactor, a silicon powder feeding tank, a silicon powder regulating valve, a hydrogen chloride feeding tank, a hydrogen chloride gas regulating valve, a temperature measuring device, a first pressure gauge, a second pressure gauge, a jacket water tank and a cooling water regulating valve; The fluidized bed reactor comprises: a fluidized bed shell, a reaction section located in the middle of the fluidized bed shell, a hydrogen chloride gas inlet and a silicon powder inlet provided on the fluidized bed shell and connected to the reaction section, and a jacket provided on the outer wall of the fluidized bed shell; The temperature measuring device is arranged inside the reaction section for measuring the reaction temperature of the reaction section; the first pressure gauge and the second pressure gauge are respectively installed at the upper and lower ends of the fluidized bed reactor for measuring the bed pressure difference of the fluidized bed reactor; The silicon powder feeding tank is connected to the silicon powder regulating valve and communicates with the silicon powder inlet through a pipeline; the hydrogen chloride feeding tank is connected to the hydrogen chloride gas regulating valve and communicates with the hydrogen chloride gas inlet through a pipeline; the jacket water tank contains cooling water, and the jacket water tank is connected to the cooling water regulating valve and communicates with the jacket on the outer wall of the fluidized bed shell through a pipeline.

4. The preparation method according to claim 3, characterized in that The hydrogen chloride gas inlet is arranged at the bottom end of the reaction section, and the silicon powder inlet is arranged at the top end of the reaction section.

5. The preparation method according to claim 3, characterized in that The fluidized bed reactor further comprises: a lower cone connected to the lower end of the reaction section, and an upper head connected to the upper end of the reaction section; the reaction section comprises a main reaction section and a secondary reaction section, wherein the main reaction section is the lower half close to the lower cone, and the secondary reaction section is the upper half close to the upper head; The temperature measuring device includes a first temperature measuring device and a second temperature measuring device. The first temperature measuring device is arranged at the upper end of the main reaction section, and the second temperature measuring device is arranged at the lower end of the main reaction section.

6. The preparation method according to claim 3, characterized in that The method for preparing trichlorosilane using the trichlorosilane synthesis system is as follows: The hydrogen chloride gas in the hydrogen chloride feeding tank continuously enters the reaction section through the hydrogen chloride gas inlet through a pipeline; simultaneously, the silicon powder in the silicon powder feeding tank continuously enters the reaction section through the silicon powder inlet through a pipeline; the first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor, and according to the test results, the flow rate of the hydrogen chloride gas is 400 standard cubic meters / h to 750 standard cubic meters / h and the feed rate of the silicon powder is 190 kg / h to 290 kg / h, so as to obtain a set of corresponding hydrogen chloride gas flow rates and silicon powder feed rates, so that the bed pressure difference of the fluidized bed reactor reaches any value between 45 kPa and 55 kPa, and the bed pressure difference fluctuates by no more than 1 kPa during the reaction; After the control is completed, the flow rate of hydrogen chloride gas and the feed amount of silicon powder are kept unchanged during the reaction process; The reaction temperature of the reaction section is tested by the temperature measuring device, and cooling water is continuously passed into the jacket using the jacket water tank for cooling according to the temperature measurement result. The flow rate of the cooling water is regulated so that the reaction temperature is maintained between 340°C and 350°C. After the regulation is completed, the flow rate of the cooling water is kept unchanged during the reaction process.

7. The preparation method according to claim 6, characterized in that The trichlorosilane synthesis system further includes a controller, which is electrically connected to the temperature measuring device, the silicon powder regulating valve, the hydrogen chloride gas regulating valve, the first pressure gauge, the second pressure gauge, and the cooling water regulating valve.

8. The preparation method according to claim 7, characterized in that At the start of the reaction, the temperature measuring device measures the temperature and sends a temperature signal to the controller. When the controller obtains the temperature signal that the reaction temperature reaches 350°C, it controls the opening of the cooling water regulating valve until the reaction temperature is maintained between 340°C and 350°C during the reaction, and maintains the cooling water regulating valve unchanged during the reaction; During the reaction process, if the controller obtains a temperature signal indicating that the reaction temperature is lower than 330° C., the controller controls the openings of the silicon powder regulating valve and the hydrogen chloride gas regulating valve to gradually decrease until they are shut down; and / or The first pressure gauge and the second pressure gauge measure the bed pressure difference of the fluidized bed reactor and provide a bed pressure difference signal to the controller. When the controller obtains any one of the bed pressure difference signals, namely, the bed pressure difference is lower than 45 kPa, higher than 55 kPa, and the bed pressure difference fluctuates by more than 1 kPa, the controller controls the opening of the silicon powder regulating valve and the hydrogen chloride gas regulating valve to gradually decrease until they are shut down.

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