A method and device for synthesizing trichlorosilane

Abstract

An embodiment of the present invention provides a method and apparatus for synthesizing trichlorosilane. The method comprises: adding silicon powder of a first particle size range to a first feed port of a fluidized bed reactor, and adding silicon powder of a second particle size range to a second feed port of the fluidized bed reactor, wherein the particle size in the first particle size range is larger than the particle size in the second particle size range, and the distance from the first feed port to the bottom of the fluidized bed reactor is larger than the distance from the second feed port to the bottom of the fluidized bed reactor; and passing a reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder to generate trichlorosilane. Silicon powder of different particle size ranges is added to the feed ports of the fluidized bed reactor corresponding to the particle size ranges, so that the silicon powder of the first particle size range added from the first feed port can block the silicon powder of the second particle size range added from the second feed port, thereby reducing the amount of silicon powder lost with the reaction gas, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-solid phase reaction, and in particular to a synthesis method and equipment of trichlorosilane. Background Art

[0002] Currently, the cold hydrogenation process is commonly used to treat silicon tetrachloride (silicon tetrachloride), a byproduct of polysilicon production. This involves converting silicon tetrachloride into trichlorosilane (TCS). This prevents environmental pollution from silicon tetrachloride while allowing the resulting TCS to participate in the polysilicon production process, achieving a closed-loop recycling system. The cold hydrogenation process involves heating a mixture of silicon tetrachloride and hydrogen, then passing it through a fluidized bed reactor. The mixture reacts with silicon powder fed into the reactor to produce TCS.

[0003] However, in the prior art, when silicon powder is added to a fluidized bed reactor, a large amount of fine silicon powder enters downstream equipment along with the reaction gas, resulting in waste of silicon powder resources and clogging or wearing out of subsequent pipelines and equipment.

[0004] It can be seen that the existing cold hydrogenation process has the problem of low silicon powder utilization. Summary of the Invention

[0005] The embodiment of the present invention provides a method and apparatus for synthesizing trichlorosilane to solve the problem of low silicon powder utilization rate in the existing cold hydrogenation process.

[0006] An embodiment of the present invention provides a method for synthesizing trichlorosilane, the method comprising: adding silicon powder in a first particle size range to a first feed port of a fluidized bed reactor, and adding silicon powder in a second particle size range to a second feed port of the fluidized bed reactor, wherein the particle sizes in the first particle size range are larger than the particle sizes in the second particle size range, and the distance from the first feed port to the bottom of the fluidized bed reactor is larger than the distance from the second feed port to the bottom of the fluidized bed reactor;

[0007] The reaction gas is introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor to react with silicon powder to generate trichlorosilane, wherein the reaction gas includes tetrachlorosilane and hydrogen.

[0008] Optionally, the reaction temperature in the fluidized bed reactor is 450° C. to 550° C., and the reaction pressure in the fluidized bed reactor is 2.4 MPa to 2.6 MPa.

[0009] Optionally, the molar ratio of hydrogen to tetrachlorosilane is 1.8 to 2.5, and the molar ratio of tetrachlorosilane to silicon powder is 2.5 to 3.5.

[0010] Optionally, the mass ratio of silicon powder having the first particle size range to silicon powder having the second particle size range is 1 to 2.

[0011] Optionally, the first particle size ranges from 10 mesh to 60 mesh, and the second particle size ranges from 60 mesh to 120 mesh.

[0012] Optionally, the ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor ranges from 7:3 to 9:1.

[0013] Optionally, after introducing the reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder, the method further comprises:

[0014] obtaining silicon powder in a third particle size range flowing out of the fluidized bed reactor through a separator connected to the top of the fluidized bed reactor, wherein the particle sizes in the third particle size range are smaller than the particle sizes in the first particle size range;

[0015] The silicon powder in the third particle size range is added to a third feed port of the fluidized bed reactor, wherein the third feed port is located between the first feed port and the second feed port.

[0016] Optionally, after introducing the reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder, the method further comprises:

[0017] obtaining silicon powder in a fourth particle size range flowing out of the separator through a filter connected to the separator, wherein the particle sizes in the fourth particle size range are smaller than the particle sizes in the second particle size range;

[0018] The silicon powder in the fourth particle size range is added to a fourth feed port of the fluidized bed reactor, where the fourth feed port is close to the bottom of the fluidized bed reactor.

[0019] The embodiment of the present invention further provides a trichlorosilane synthesis device for implementing the above-mentioned trichlorosilane synthesis method, wherein the trichlorosilane synthesis device comprises:

[0020] A fluidized bed reactor comprising a first feed port for adding silicon powder having a first particle size range, a second feed port for adding silicon powder having a second particle size range, a fluidized bed reactor inlet for introducing a reaction gas, and a fluidized bed reactor outlet for discharging a target substance, wherein the reaction gas comprises tetrachlorosilane and hydrogen, and the target substance comprises trichlorosilane;

[0021] The distance from the first feed port to the bottom of the fluidized bed reactor is greater than the distance from the second feed port to the bottom of the fluidized bed reactor, the inlet of the fluidized bed reactor is located near the bottom of the fluidized bed reactor, and the outlet of the fluidized bed reactor is located near the top of the fluidized bed reactor.

[0022] Optionally, the fluidized bed reactor further comprises a third feed port for adding silicon powder in a third particle size range, and a fourth feed port for adding silicon powder in a fourth particle size range, wherein the third feed port is located between the first feed port and the second feed port, and the fourth feed port is close to the bottom of the fluidized bed reactor;

[0023] The synthesis equipment of trichlorosilane also includes:

[0024] a separator, wherein the inlet of the separator is connected to the outlet of the fluidized bed reactor to obtain the silicon powder in the third particle size range flowing out of the fluidized bed reactor, and the first outlet of the separator is connected to the third feed port;

[0025] a filter, wherein the inlet of the filter is connected to the second outlet of the separator to obtain the silicon powder in the fourth particle size range flowing out of the separator, and the first outlet of the filter is connected to the fourth feed port;

[0026] and / or,

[0027] The fluidized bed reactor has an expansion zone and a non-expansion zone. The expansion zone is located between the outlet of the fluidized bed reactor and the first feed inlet. The diameter of the expansion zone is larger than that of the non-expansion zone.

[0028] In an embodiment of the present invention, silicon powder of different particle size ranges is added to the feed port of the fluidized bed reactor corresponding to the particle size range, so that the silicon powder of the first particle size range added from the first feed port can block the silicon powder of the second particle size range added from the second feed port, thereby reducing the amount of silicon powder lost with the reaction gas, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder, thereby improving the efficiency of generating trichlorosilane from the silicon powder and the reaction gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 1 is a schematic flow chart of a method for synthesizing trichlorosilane provided in an embodiment of the present invention;

[0031] Figure 2 It is a structural schematic diagram of a trichlorosilane synthesis device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] The terms "first," "second," and the like in the specification and claims of the present invention are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the structures used in this manner are interchangeable where appropriate, so that the embodiments of the present invention can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," and the like are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, the term "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship.

[0034] See also Figure 1 , Figure 1 Schematic diagram of the synthesis method of trichlorosilane provided by the embodiment of the present invention. Figure 1 As shown, a method for synthesizing trichlorosilane provided by an embodiment of the present invention comprises the following steps:

[0035] Step 101: Add silicon powder of a first particle size range to a first feed port of a fluidized bed reactor, and add silicon powder of a second particle size range to a second feed port of the fluidized bed reactor, wherein the particle size in the first particle size range is larger than the particle size in the second particle size range, and the distance from the first feed port to the bottom of the fluidized bed reactor is larger than the distance from the second feed port to the bottom of the fluidized bed reactor;

[0036] The fluidized bed reactor is provided with feed ports for silicon powder of different particle size ranges. The silicon powder is classified according to its particle size. The classification can be performed by setting the mesh size of a sieve to distinguish silicon powder with a larger particle size (i.e., a first particle size range) from silicon powder with a smaller particle size (i.e., a second particle size range). Silicon powder of the first particle size range is added to the first feed port of the fluidized bed reactor, and silicon powder of the second particle size range is added to the second feed port of the fluidized bed reactor. The silicon powder reacts with the reaction gas in step 102 to produce trichlorosilane.

[0037] Among them, the distance from the first feed port to the bottom of the fluidized bed reactor is greater than the distance from the second feed port to the bottom of the fluidized bed reactor, that is, in the height direction of the fluidized bed reactor, the height of the first feed port is greater than the height of the second feed port. Since the particle size in the first particle size range is greater than the particle size in the second particle size range, after the silicon powder in the first particle size range is added to the fluidized bed reactor from the first feed port, it moves toward the bottom of the fluidized bed reactor under the action of gravity, and can block the silicon powder in the second particle size range added to the fluidized bed reactor from the second feed port. In this way, the amount of silicon powder entering the downstream equipment with the reaction gas is reduced, the reaction time of the silicon powder is increased, and the utilization rate of the silicon powder is improved.

[0038] Step 102: introducing a reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with silicon powder to generate trichlorosilane. The reaction gas includes tetrachlorosilane and hydrogen.

[0039] After silicon powder of the second particle size range is added to the fluidized bed reactor through the second feed port, it moves toward the top of the fluidized bed reactor under the thrust of the incoming reaction gas. The silicon powder of the first particle size range added through the first feed port blocks the silicon powder of the second particle size range added through the second feed port. This reduces silicon powder loss, increases the reaction time of silicon powder with tetrachlorosilane and hydrogen, and thus improves the efficiency of trichlorosilane production from silicon powder and reaction gas.

[0040] In this embodiment, silicon powder of different particle size ranges is added to the feed port of the fluidized bed reactor with the corresponding particle size range, so that the silicon powder of the first particle size range added from the first feed port can block the silicon powder of the second particle size range added from the second feed port, thereby reducing the amount of silicon powder lost with the reaction gas, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder, thereby improving the efficiency of the silicon powder and the reaction gas in generating trichlorosilane.

[0041] The silicon powder in the first particle size range and the silicon powder in the second particle size range can be obtained by screening the silicon powder before adding it to the fluidized bed reactor for reaction. The silicon powder in the first particle size range and the silicon powder in the second particle size range can also be obtained by screening the silicon powder recovered from the top outlet of the fluidized bed reactor.

[0042] The silicon powder can be new silicon powder that has not entered the fluidized bed reactor, or can be silicon powder recovered from the top outlet of the fluidized bed reactor.

[0043] The method may include:

[0044] Before the silicon powder is added to the fluidized bed reactor, new silicon powder that has not entered the fluidized bed reactor is screened to obtain silicon powder with a first particle size range and silicon powder with a second particle size range;

[0045] The method may include:

[0046] Silicon powder flowing out of the top outlet of the fluidized bed reactor is recovered and sieved to obtain silicon powder having a first particle size range and silicon powder having a second particle size range. The reaction temperature in the fluidized bed reactor may be 450°C to 550°C. For example, the reaction temperature in the fluidized bed reactor may be 540°C. This can reduce the decomposition of trichlorosilane (SiHCl3) and catalyst damage at excessively high temperatures, and can also reduce the low reaction rate and catalytic efficiency at excessively low temperatures.

[0047] The reaction pressure in the fluidized bed reactor can be 2.4 MPa to 2.6 MPa. For example, the reaction pressure in the fluidized bed reactor can be 2.5 MPa. This can avoid excessively high pressure, which can increase the cost of the fluidized bed reactor. Furthermore, it can reduce the slow reaction rate caused by excessively low pressure, thereby improving the reaction rate while balancing equipment quality and cost.

[0048] The molar ratio of hydrogen to tetrachlorosilane can be 1.8 to 2.5, and the molar ratio of tetrachlorosilane to silicon powder can be 2.5 to 3.5, thereby improving the efficiency of generating trichlorosilane from silicon powder, tetrachlorosilane and hydrogen, and improving the utilization rate of silicon powder.

[0049] The mass ratio of silicon powder in the first particle size range to silicon powder in the second particle size range can be 1 to 2. This allows the silicon powder in the first particle size range and the silicon powder in the second particle size range to gather in the middle of the fluidized bed reactor, thereby improving the reaction efficiency of the silicon powder. This reduces the situation where the silicon powder in the first particle size range and the silicon powder in the second particle size range gather at the bottom of the fluidized bed reactor when there is too much silicon powder in the first particle size range, resulting in insufficient contact between the silicon powder and the reaction gas; and reduces the situation where the silicon powder in the first particle size range and the silicon powder in the second particle size range gather at the top of the fluidized bed reactor when there is too little silicon powder in the first particle size range, resulting in the silicon powder easily flowing out with the reaction gas. As a result, the efficiency of the silicon powder, tetrachlorosilane, and hydrogen in generating trichlorosilane is improved, and the utilization rate of the silicon powder is improved.

[0050] Wherein, the first particle size range can be 10 mesh to 60 mesh (equivalent to 0.25 mm to 2 mm), and the second particle size range is 60 mesh to 120 mesh (equivalent to 0.125 mm to 0.25 mm). In this way, the particle size in the first particle size range is larger than the particle size in the second particle size range. In the height direction of the fluidized bed reactor, the height of the first feed port is greater than the height of the second feed port. Therefore, after the silicon powder in the first particle size range is added to the fluidized bed reactor from the first feed port, it moves toward the bottom of the fluidized bed reactor under the action of gravity; after the silicon powder in the second particle size range is added to the fluidized bed reactor from the second feed port, it moves toward the top of the fluidized bed reactor under the thrust of the introduced reaction gas, so that the silicon powder in the first particle size range and the silicon powder in the second particle size range gather in the middle of the fluidized bed reactor. The silicon powder in the first particle size range blocks the silicon powder in the second particle size range, reducing the amount of silicon powder entering the downstream equipment with the reaction gas, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder.

[0051] Wherein, the ratio between the distance from the first feed port to the bottom of the fluidized bed reactor and the distance from the second feed port to the bottom of the fluidized bed reactor is in the range of 7:3 to 9:1. Exemplarily, the distance from the top to the bottom of the fluidized bed reactor may be 22573 mm, wherein the distance of the fluidized bed flow area may be 18280 mm. The first feed port is set at a position of 15801.1 mm to 20315.7 mm from the bottom of the fluidized bed reactor, and the second feed port is set at a position of 2257.3 mm to 6771.9 mm from the bottom of the fluidized bed reactor, so that the distance from the first feed port to the bottom of the fluidized bed reactor is greater than the distance from the second feed port to the bottom of the fluidized bed reactor, that is, in the height direction of the fluidized bed reactor, the height of the first feed port is greater than the height of the second feed port. Since the particle size in the first particle size range is greater than the particle size in the second particle size range, the silicon powder in the first particle size range is added to the fluidized bed from the first feed port. After entering the reactor, it moves toward the bottom of the fluidized bed reactor under the action of gravity, and can block the silicon powder of the second particle size range added to the fluidized bed reactor from the second feed inlet; and after the silicon powder of the second particle size range is added to the fluidized bed reactor from the second feed inlet, it moves toward the top of the fluidized bed reactor under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range and the silicon powder in the second particle size range gather in the middle of the fluidized bed reactor, reducing the amount of silicon powder entering the downstream equipment with the reaction gas, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder.

[0052] In this way, silicon powder of different particle size ranges is added to the feed port of the fluidized bed reactor with the corresponding particle size range, so that the silicon powder of the first particle size range added from the first feed port can block the silicon powder of the second particle size range added from the second feed port, thereby reducing the amount of silicon powder lost with the reaction gas; at the same time, the reaction time of the silicon powder is increased, so that the contact time between the silicon powder and the reaction gas is greater than or equal to 20 seconds, reducing the situation where insufficient contact time leads to insufficient reaction, thereby improving the utilization rate of the silicon powder and improving the efficiency of the silicon powder and the reaction gas to generate trichlorosilane.

[0053] In some optional embodiments, within the fluidized bed reactor, the gas flow rate near the inner sidewall is greater than the gas flow rate in the central region. This prevents silicon powder from accumulating on the inner sidewall, reduces the resistance of the inner sidewall, and improves the efficiency of trichlorosilane production from silicon powder and reaction gas.

[0054] In some optional embodiments, at a position close to the outlet of the fluidized bed reactor, the pressure at that position can be reduced by extracting gas, lowering the temperature, etc., thereby reducing the amount of silicon powder discharged through the outlet of the fluidized bed reactor along with the reaction gas, thereby improving the utilization rate of the silicon powder.

[0055] In other optional embodiments, an expansion zone is provided near the outlet of the fluidized bed reactor, and the diameter of the expansion zone is larger than the diameter of other areas on the fluidized bed reactor to reduce the pressure in the expansion zone, thereby reducing the amount of silicon powder discharged from the outlet of the fluidized bed reactor along with the reaction gas, thereby improving the utilization rate of the silicon powder.

[0056] In some optional embodiments, after introducing the reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder, the method further comprises:

[0057] obtaining silicon powder in a third particle size range flowing out of the fluidized bed reactor through a separator connected to the top of the fluidized bed reactor, wherein the particle size in the third particle size range is smaller than the particle size in the first particle size range and larger than a separation limit (200 μm) of the separator;

[0058] The silicon powder in the third particle size range is added to a third feed port of the fluidized bed reactor, wherein the third feed port is located between the first feed port and the second feed port.

[0059] In this embodiment, a separator is connected to the outlet of the fluidized bed reactor to capture silicon powder flowing out of the fluidized bed reactor with the reaction gas. The silicon powder flowing out is post-reaction silicon powder, and thus has a particle size within a third particle size range, which is smaller than the particle size within the first particle size range. The silicon powder flowing out of the fluidized bed reactor with the reaction gas is recovered by the separator and fed into the fluidized bed reactor through the third feed port, forming a closed-loop silicon powder cycle, reducing silicon powder loss and improving silicon powder utilization.

[0060] At the same time, feed ports are set at different heights of the fluidized bed reactor according to the particle sizes of the fed silicon powder (i.e. silicon powder in the first particle size range and silicon powder in the second particle size range) and the recovered silicon powder (i.e. silicon powder in the third particle size range).

[0061] Specifically, the third feed port is set between the first feed port and the second feed port. After the silicon powder in the first particle size range is added to the fluidized bed reactor from the first feed port, it moves toward the bottom of the fluidized bed reactor under the action of gravity, and can block the silicon powder in the second particle size range added to the fluidized bed reactor from the second feed port; and after the silicon powder in the second particle size range is added to the fluidized bed reactor from the second feed port, it moves toward the top of the fluidized bed reactor under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range and the silicon powder in the second particle size range are gathered in the middle of the fluidized bed reactor; and the silicon powder in the first particle size range recovered by the separator is re-added to the middle of the fluidized bed reactor from the third feed port, and gathered with the silicon powder in the fluidized bed reactor, thereby realizing the closed-loop circulation of the silicon powder, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder.

[0062] In some optional embodiments, after introducing the reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder, the method further comprises:

[0063] obtaining silicon powder in a fourth particle size range flowing out of the separator through a filter connected to the separator, wherein the particle size in the fourth particle size range is smaller than the particle size in the second particle size range and larger than a separation limit (1 μm) of the filter;

[0064] The silicon powder in the fourth particle size range is added to a fourth feed port of the fluidized bed reactor, where the fourth feed port is close to the bottom of the fluidized bed reactor.

[0065] In this embodiment, a separator is connected to the outlet of the fluidized bed reactor to capture silicon powder flowing out of the fluidized bed reactor with the reaction gas. Silicon powder flowing out of the fluidized bed reactor with the reaction gas in a third particle size range is post-reaction silicon powder, and thus the particle size within the third particle size range is smaller than the particle size within the first particle size range. Furthermore, a filter is connected to the outlet of the separator to capture silicon powder flowing out of the separator with the reaction gas. Silicon powder flowing out of the separator with the reaction gas in a fourth particle size range is post-reaction silicon powder separated by the separator, and thus the particle size within the fourth particle size range is smaller than the particle size within the second particle size range.

[0066] In this way, the silicon powder flowing out of the fluidized bed reactor along with the reaction gas is recovered through the separator, and then added to the fluidized bed reactor through the third feed port; and the silicon powder flowing out of the separator along with the reaction gas is recovered through the filter, and then added to the fluidized bed reactor through the fourth feed port, forming a closed-loop circulation of silicon powder, further reducing the loss of silicon powder and further improving the utilization rate of silicon powder.

[0067] At the same time, the feed silicon powder raw material (i.e., silicon powder in the first particle size range and silicon powder in the second particle size range) and the recovered silicon powder (i.e., silicon powder in the third particle size range and silicon powder in the fourth particle size range) are fed at different heights of the fluidized bed reactor.

[0068] Specifically, the third feed port is located between the first feed port and the second feed port, and the fourth feed port is close to the bottom of the fluidized bed reactor, wherein the fourth feed port and the second feed port can be located on opposite sides of the fluidized bed reactor, respectively, and the distance from the fourth feed port to the bottom of the fluidized bed reactor is less than or equal to the distance from the second feed port to the bottom of the fluidized bed reactor.

[0069] The silicon powder in the third particle size range is silicon powder recovered from the fluidized bed reactor by the separator, and the silicon powder in the fourth particle size range is silicon powder recovered from the separator by the filter. The silicon powder in the third particle size range is added back to the middle of the fluidized bed reactor through the third feed port, and the silicon powder in the fourth particle size range is added back to the bottom of the fluidized bed reactor through the fourth feed port. After silicon powder in the first particle size range is added to the fluidized bed reactor from the first feed port, it moves toward the bottom of the fluidized bed reactor under the action of gravity, and can block the silicon powder added to the fluidized bed reactor from the second feed port and the fourth feed port; and after silicon powder in the second particle size range is added to the fluidized bed reactor from the second feed port, and silicon powder in the fourth particle size range is added to the fluidized bed reactor from the fourth feed port, they move toward the top of the fluidized bed reactor under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range, the silicon powder in the second particle size range, the silicon powder in the third particle size range and the silicon powder in the fourth particle size range gather in the middle of the fluidized bed reactor, realizing the closed-loop circulation of the silicon powder, increasing the reaction time of the silicon powder and improving the utilization rate of the silicon powder.

[0070] The embodiment of the present invention also provides a trichlorosilane synthesis device for implementing the above-mentioned trichlorosilane synthesis method, such as Figure 2 As shown, the synthesis equipment of trichlorosilane includes:

[0071] A fluidized bed reactor 10, comprising a first feed port 101 for adding silicon powder in a first particle size range, a second feed port 102 for adding silicon powder in a second particle size range, a fluidized bed reactor inlet for introducing a reaction gas, and a fluidized bed reactor outlet for discharging a target substance, wherein the reaction gas comprises tetrachlorosilane and hydrogen, and the target substance comprises trichlorosilane;

[0072] Among them, the distance from the first feed inlet 101 to the bottom of the fluidized bed reactor is greater than the distance from the second feed inlet 102 to the bottom of the fluidized bed reactor, the inlet of the fluidized bed reactor is located near the bottom of the fluidized bed reactor, and the outlet of the fluidized bed reactor is located near the top of the fluidized bed reactor.

[0073] In this embodiment, a first feed port 101 and a second feed port 102 are provided on the fluidized bed reactor 10, so that the distance from the first feed port 101 to the bottom of the fluidized bed reactor is greater than the distance from the second feed port 102 to the bottom of the fluidized bed reactor, and the silicon powder is classified according to the particle size of the silicon powder to distinguish silicon powder with a larger particle size (i.e., the first particle size range) and silicon powder with a smaller particle size (i.e., the second particle size range). Silicon powder in a first particle size range is added to the first feed port 101 of the fluidized bed reactor 10, and silicon powder in a second particle size range is added to the second feed port 102 of the fluidized bed reactor 10. Since the particle size in the first particle size range is larger than the particle size in the second particle size range, the silicon powder in the first particle size range moves toward the bottom of the fluidized bed reactor 10 under the action of gravity, and can block the silicon powder in the second particle size range added to the fluidized bed reactor from the second feed port; and the silicon powder in the second particle size range moves toward the top of the fluidized bed reactor 10 under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range and the silicon powder in the second particle size range gather in the middle of the fluidized bed reactor, reducing the amount of silicon powder entering the downstream equipment with the reaction gas, increasing the reaction time of the silicon powder, improving the utilization rate of the silicon powder, and improving the efficiency of the silicon powder and the reaction gas in generating trichlorosilane.

[0074] Optionally, the fluidized bed reactor further includes a third feed port 103 for adding silicon powder in a third particle size range, and a fourth feed port 104 for adding silicon powder in a fourth particle size range, wherein the third feed port 103 is located between the first feed port 101 and the second feed port 102, and the fourth feed port 104 is close to the bottom of the fluidized bed reactor 10;

[0075] The synthesis equipment of trichlorosilane also includes:

[0076] a separator 20, wherein the inlet of the separator 20 is connected to the outlet of the fluidized bed reactor to obtain the silicon powder in the third particle size range flowing out of the fluidized bed reactor 10, and the first outlet of the separator 20 is connected to the third feed port 103;

[0077] a filter 30, wherein the inlet of the filter 30 is connected to the second outlet of the separator 20 to obtain the silicon powder in the fourth particle size range flowing out of the separator 20, and the first outlet of the filter 30 is connected to the fourth feed port;

[0078] and / or,

[0079] The fluidized bed reactor has an expansion zone and a non-expansion zone. The expansion zone is located between the outlet of the fluidized bed reactor and the first feed inlet. The diameter of the expansion zone is larger than that of the non-expansion zone.

[0080] Specifically, the trichlorosilane synthesis equipment may include a fluidized bed reactor 10, a separator 20 (i.e., an external cyclone separator), a filter 30, an internal cyclone separator 40, a first storage tank 50, a first pressurized tank 60, a second storage tank 70, a second pressurized tank 80, and a heater 90. Silicon tetrachloride and hydrogen are mixed and heated in heater 90, and then the reaction gas is introduced into the fluidized bed reactor 10. In the fluidized bed reactor 10, the reaction gas reacts with the silicon powder added to the fluidized bed reactor to produce trichlorosilane. After the reaction, the internal cyclone separator 40 can be used to initially separate silicon powder particles of a first gradient particle size, the separator 20 can further separate silicon powder particles of a second gradient particle size, and the filter 30 can further separate silicon powder particles of a third gradient particle size, wherein the first gradient particle size is larger than the second gradient particle size, and the second gradient particle size is larger than the third gradient particle size. The silicon powder particles separated in the three stages are recovered and transported to the fluidized bed respectively, and are fed at different heights of the fluidized bed reactor 10 according to the particle size of the silicon powder particles.

[0081] When adding silica fume:

[0082] The silicon powder is classified according to its particle size to distinguish silicon powder with a larger particle size (ie, a first particle size range) from silicon powder with a smaller particle size (ie, a second particle size range). Silicon powder in a first particle size range is added to the first feed port 101 of the fluidized bed reactor 10, and silicon powder in a second particle size range is added to the second feed port 102 of the fluidized bed reactor 10. Since the particle size in the first particle size range is larger than the particle size in the second particle size range, the silicon powder in the first particle size range moves toward the bottom of the fluidized bed reactor 10 under the action of gravity, and can block the silicon powder in the second particle size range added to the fluidized bed reactor from the second feed port; and the silicon powder in the second particle size range moves toward the top of the fluidized bed reactor 10 under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range and the silicon powder in the second particle size range gather in the middle of the fluidized bed reactor, reducing the amount of silicon powder entering the downstream equipment with the reaction gas, increasing the reaction time of the silicon powder, improving the utilization rate of the silicon powder, and improving the efficiency of the silicon powder and the reaction gas in generating trichlorosilane.

[0083] When recycling silicon powder:

[0084] The silicon powder separated by the built-in cyclone separator 40 can be directly transported to the bottom of the fluidized bed reactor 10. The silicon powder separated by the separator 20 (i.e., the external cyclone separator) is first transported to the first storage tank 50. After the silicon powder flowing out of the self-fluidized bed reactor 10 recovered in the first storage tank 50 reaches a certain height, the recovered silicon powder is transported to the first pressurized tank 60. After the first pressurized tank 60 is pressurized by the reaction gas (i.e., silicon tetrachloride and hydrogen), the recovered silicon powder flowing out of the self-fluidized bed reactor is transported to the middle of the fluidized bed reactor 10 through the third feed port 103, and aggregated with the silicon powder in the fluidized bed reactor, thereby realizing the closed-loop circulation of the silicon powder, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder. Among them, multiple feeding tanks can be designed to have more than one for use. The silicon powder separated by the filter 30 is first transported to the second storage tank 70 by intermittent blowing of nitrogen. After the silicon powder flowing out of the separator 20 recovered in the second storage tank 70 reaches a certain height, the recovered silicon powder is transported to the second pressurized tank 80. The second pressurized tank 80 can be pressurized by the reaction gas (i.e., silicon tetrachloride and hydrogen), and the recovered silicon powder flowing out of the separator 20 is transported to the bottom of the fluidized bed reactor 10 through the fourth feed port 104, and aggregated with the silicon powder in the fluidized bed reactor, thereby realizing a closed-loop circulation of the silicon powder, increasing the reaction time of the silicon powder, and improving the utilization rate of the silicon powder. Among them, multiple feeding tanks can be designed to have more reserves.

[0085] In this way, the silicon powder flowing out of the fluidized bed reactor 10 along with the reaction gas is recovered through the separator 20 and then re-added to the middle of the fluidized bed reactor 10 through the third feed port 103; and the silicon powder flowing out of the fluidized bed reactor 20 along with the reaction gas is recovered through the filter 30 and then re-added to the bottom of the fluidized bed reactor 10 through the fourth feed port 104, forming a closed-loop circulation of silicon powder, thereby further reducing the loss of silicon powder. After silicon powder in the first particle size range is added to the fluidized bed reactor 10 from the first feed port 101, it moves toward the bottom of the fluidized bed reactor 10 under the action of gravity, and can block the silicon powder added to the fluidized bed reactor 10 from the second feed port 102 and the fourth feed port 104; and after silicon powder in the second particle size range is added to the fluidized bed reactor from the second feed port 102, and silicon powder in the fourth particle size range is added to the fluidized bed reactor from the fourth feed port 104, they move toward the top of the fluidized bed reactor 10 under the thrust of the introduced reaction gas. Under the blocking effect of the silicon powder in the first particle size range, the silicon powder in the first particle size range, the silicon powder in the second particle size range, the silicon powder in the third particle size range and the silicon powder in the fourth particle size range gather in the middle of the fluidized bed reactor 10, which increases the reaction time of the silicon powder while improving the utilization rate of the silicon powder.

[0086] In addition, an expansion zone can be provided near the outlet of the fluidized bed reactor. The expansion zone is located between the outlet of the fluidized bed reactor and the first feed port 101. The diameter of the expansion zone is larger than the diameters of other areas of the fluidized bed reactor. This reduces the pressure in the expansion zone, thereby reducing the amount of silicon powder discharged from the outlet of the fluidized bed reactor along with the reaction gas, thereby improving the utilization rate of the silicon powder. The pressure in the expansion zone can also be reduced by extracting gas or lowering the temperature, thereby reducing the amount of silicon powder discharged from the outlet of the fluidized bed reactor along with the reaction gas, thereby improving the utilization rate of the silicon powder.

[0087] The present invention will be further described below through some specific examples.

[0088] Example 1:

[0089] adding silicon powder of a first particle size range to a first feed port of a fluidized bed reactor, and adding silicon powder of a second particle size range to a second feed port of the fluidized bed reactor, wherein the particles in the first particle size range are larger than the particles in the second particle size range; introducing a reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder to generate trichlorosilane, wherein the reaction gas comprises tetrachlorosilane and hydrogen;

[0090] The reaction temperature in the fluidized bed reactor is 550° C., the reaction pressure in the fluidized bed reactor is 2.4 MPa; the molar ratio of hydrogen to tetrachlorosilane is 1.8, the molar ratio of tetrachlorosilane to silicon powder is 3.5, the mass ratio of silicon powder having a first particle size range to silicon powder having a second particle size range is 2, the first particle size range is 10 mesh to 40 mesh, and the second particle size range is 60 mesh to 90 mesh.

[0091] The ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 9:1.

[0092] The utilization rate of silicon powder in the above embodiment is 92.5%.

[0093] Example 2:

[0094] The difference between Example 2 and Example 1 is that:

[0095] In Example 2, the reaction temperature in the fluidized bed reactor is 450° C., and the reaction pressure in the fluidized bed reactor is 2.6 MPa.

[0096] The utilization rate of silicon powder in the above embodiment is 91.6%.

[0097] Example 3:

[0098] The difference between Example 3 and Example 1 is that:

[0099] In Example 3, the molar ratio of hydrogen to tetrachlorosilane is 2.5, the molar ratio of tetrachlorosilane to silicon powder is 2.5, and the mass ratio of silicon powder having the first particle size range to silicon powder having the second particle size range is 1.

[0100] The utilization rate of silicon powder in the above embodiment is 92.3%.

[0101] Example 4:

[0102] The difference between Example 4 and Example 1 is that:

[0103] In Example 4, the first particle size range is 40 mesh to 60 mesh, and the second particle size range is 70 mesh to 120 mesh.

[0104] The utilization rate of silicon powder in the above embodiment is 92.7%.

[0105] Example 5:

[0106] The difference between Example 5 and Example 1 is that:

[0107] In Example 5, the ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 7:3.

[0108] The utilization rate of silicon powder in the above embodiment is 90.4%.

[0109] Example 6:

[0110] The difference between Example 6 and Example 1 is that:

[0111] In Example 6, the ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 5:1.

[0112] The utilization rate of silicon powder in the above embodiment is 91.3%.

[0113] Comparative Example 1:

[0114] Add all the silicon powder to the first feed port of the fluidized bed reactor, and introduce the reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder to generate trichlorosilane, wherein the reaction gas includes tetrachlorosilane and hydrogen;

[0115] The reaction temperature in the fluidized bed reactor is 550° C., the reaction pressure in the fluidized bed reactor is 2.4 MPa; the molar ratio of hydrogen to tetrachlorosilane is 1.8, the molar ratio of tetrachlorosilane to silicon powder is 3.5, the mass ratio of silicon powder having a first particle size range to silicon powder having a second particle size range is 2, the first particle size range is 10 mesh to 40 mesh, and the second particle size range is 60 mesh to 90 mesh.

[0116] The ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 9:1.

[0117] The utilization rate of silicon powder in the above embodiment is 58.7%.

[0118] Comparative Example 2:

[0119] Add all the silicon powder to the second feed port of the fluidized bed reactor, and introduce reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with the silicon powder to generate trichlorosilane, wherein the reaction gas includes tetrachlorosilane and hydrogen;

[0120] The reaction temperature in the fluidized bed reactor is 550° C., the reaction pressure in the fluidized bed reactor is 2.4 MPa; the molar ratio of hydrogen to tetrachlorosilane is 1.8, the molar ratio of tetrachlorosilane to silicon powder is 3.5, the mass ratio of silicon powder having a first particle size range to silicon powder having a second particle size range is 2, the first particle size range is 10 mesh to 40 mesh, and the second particle size range is 60 mesh to 90 mesh.

[0121] The ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 9:1.

[0122] The utilization rate of silicon powder in the above embodiment is 59.4%.

[0123] Example 7:

[0124] Step 1: adding silicon powder of a first particle size range to a first feed port of a fluidized bed reactor, and adding silicon powder of a second particle size range to a second feed port of the fluidized bed reactor, wherein the particle size in the first particle size range is larger than the particle size in the second particle size range; wherein the mass ratio of the silicon powder of the first particle size range to the silicon powder of the second particle size range is 2, the first particle size range is 30 mesh to 60 mesh, and the second particle size range is 90 mesh to 120 mesh, and the ratio of the distance from the first feed port to the bottom of the fluidized bed reactor to the distance from the second feed port to the bottom of the fluidized bed reactor is 9:1;

[0125] Step 2: introducing a reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with silicon powder to generate trichlorosilane, wherein the reaction gas comprises tetrachlorosilane and hydrogen; wherein the reaction temperature in the fluidized bed reactor is 550° C., the reaction pressure in the fluidized bed reactor is 2.6 MPa; the molar ratio of hydrogen to tetrachlorosilane is 1.8, and the molar ratio of tetrachlorosilane to silicon powder is 3.5;

[0126] Step 3: Receiving silicon powder in a third particle size range from the fluidized bed reactor through a separator connected to the top of the fluidized bed reactor, wherein the particles in the third particle size range are smaller than the particles in the first particle size range; and adding the silicon powder in the third particle size range to a third feed port of the fluidized bed reactor, wherein the third feed port is located between the first and second feed ports. The third particle size range is 60 mesh to 90 mesh, and the ratio of the distance from the third feed port to the first feed port to the distance from the third feed port to the second feed port is 1:1.

[0127] The utilization rate of silicon powder in the above embodiment is 94.2%.

[0128] Example 8:

[0129] The difference between Example 8 and Example 7 is that:

[0130] In step 1 of Example 8, the ratio of the distance from the first feed inlet to the bottom of the fluidized bed reactor to the distance from the second feed inlet to the bottom of the fluidized bed reactor is 7:3.

[0131] The utilization rate of silicon powder in the above embodiment is 94.4%.

[0132] Example 9:

[0133] The difference between Example 9 and Example 7 is that:

[0134] In step 2 of Example 9, the reaction temperature in the fluidized bed reactor is 450° C., the reaction pressure in the fluidized bed reactor is 2.4 MPa, the molar ratio of hydrogen to tetrachlorosilane is 2.5, and the molar ratio of tetrachlorosilane to silicon powder is 2.5.

[0135] The utilization rate of silicon powder in the above embodiment is 94.0%.

[0136] Example 10:

[0137] The difference between Example 10 and Example 7 is that:

[0138] In step 1 of Example 10, the mass ratio of the silicon powder having the first particle size range to the silicon powder having the second particle size range is 1.

[0139] The utilization rate of silicon powder in the above embodiment is 93.9%.

[0140] Example 11:

[0141] The difference between Example 11 and Example 7 is that:

[0142] In step 1 of Example 11, the first particle size range is 10 mesh to 40 mesh, and the second particle size range is 60 mesh to 90 mesh.

[0143] The utilization rate of silicon powder in the above embodiment is 94.2%.

[0144] Example 12:

[0145] The difference between Example 12 and Example 7 is that:

[0146] Step 3 of Example 11 also includes:

[0147] Silicon powder in a fourth particle size range flowing out of the fluidized bed reactor is obtained through a separator connected to the top of the fluidized bed reactor, and the silicon powder in the fourth particle size range is added to the fourth feed port of the fluidized bed reactor, where the fourth feed port is close to the bottom of the fluidized bed reactor; the fourth particle size range is 120 mesh to 150 mesh.

[0148] The utilization rate of silicon powder in the above embodiment is 95.1%.

[0149] Comparative Example 3:

[0150] The difference between Comparative Example 3 and Example 7 is:

[0151] In step 1 of Comparative Example 3, silicon powders having the first particle size range and the second particle size range are added to the first feed port of the fluidized bed reactor, and no silicon powder is added to the second feed port.

[0152] The utilization rate of silicon powder in the above comparative example is: 60.3%.

[0153] Comparative Example 4:

[0154] The difference between Comparative Example 4 and Example 7 is:

[0155] In step 1 of Comparative Example 4, silicon powders having the first particle size range and the second particle size range are added to the second feed port of the fluidized bed reactor, and no silicon powder is added to the first feed port.

[0156] The utilization rate of silicon powder in the above comparative example is: 60.8%.

[0157] Comparative Example 5:

[0158] The difference between Comparative Example 5 and Example 7 is:

[0159] In step 2 of Comparative Example 5, the reaction temperature in the fluidized bed reactor was 400° C., the reaction pressure in the fluidized bed reactor was 2.3 MPa, the molar ratio of hydrogen to tetrachlorosilane was 1.5, and the molar ratio of tetrachlorosilane to silicon powder was 2.

[0160] The utilization rate of silicon powder in the above comparative example is: 72.4%.

[0161] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present invention is not limited to performing functions in the order discussed, but may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0162] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for synthesizing trichlorosilane, characterized in that: The method comprises: adding silicon powder of a first particle size range to a first feed port of a fluidized bed reactor, and adding silicon powder of a second particle size range to a second feed port of the fluidized bed reactor, wherein the particle size in the first particle size range is larger than the particle size in the second particle size range, and the distance from the first feed port to the bottom of the fluidized bed reactor is larger than the distance from the second feed port to the bottom of the fluidized bed reactor; wherein the mass ratio of the silicon powder of the first particle size range to the silicon powder of the second particle size range is 1 to 2; and the ratio of the distance from the first feed port to the bottom of the fluidized bed reactor to the distance from the second feed port to the bottom of the fluidized bed reactor is in a range of 7:3 to 9:1; Passing reaction gas from the bottom of the fluidized bed reactor into the fluidized bed reactor to react with silicon powder to generate trichlorosilane, wherein the reaction gas includes tetrachlorosilane and hydrogen; After the reaction gas is introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor to react with the silicon powder, the method further comprises: obtaining silicon powder in a third particle size range flowing out of the fluidized bed reactor through a separator connected to the top of the fluidized bed reactor, wherein the particle sizes in the third particle size range are smaller than the particle sizes in the first particle size range; adding the silicon powder of the third particle size range to a third feed port of the fluidized bed reactor, wherein the third feed port is located between the first feed port and the second feed port; After the reaction gas is introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor to react with the silicon powder, the method further comprises: obtaining silicon powder in a fourth particle size range flowing out of the separator through a filter connected to the separator, wherein the particle sizes in the fourth particle size range are smaller than the particle sizes in the second particle size range; The silicon powder in the fourth particle size range is added to the fourth feed port of the fluidized bed reactor, and the fourth feed port is close to the bottom of the fluidized bed reactor; wherein the fourth feed port and the second feed port are located on opposite sides of the fluidized bed reactor, and the distance from the fourth feed port to the bottom of the fluidized bed reactor is less than or equal to the distance from the second feed port to the bottom of the fluidized bed reactor.

2. The method according to claim 1, characterized in that The reaction temperature in the fluidized bed reactor is 450° C. to 550° C., and the reaction pressure in the fluidized bed reactor is 2.4 MPa to 2.6 MPa.

3. The method according to claim 1, characterized in that The molar ratio of hydrogen to tetrachlorosilane is 1.8 to 2.5, and the molar ratio of tetrachlorosilane to silicon powder is 2.5 to 3.

5.

4. The method according to claim 1, wherein The first particle size ranges from 10 mesh to 60 mesh, and the second particle size ranges from 60 mesh to 120 mesh.

5. A synthesis device for trichlorosilane, characterized in that: For implementing the method according to any one of claims 1 to 3, the trichlorosilane synthesis equipment comprises: A fluidized bed reactor comprising a first feed port for adding silicon powder having a first particle size range, a second feed port for adding silicon powder having a second particle size range, a fluidized bed reactor inlet for introducing a reaction gas, and a fluidized bed reactor outlet for discharging a target substance, wherein the reaction gas comprises tetrachlorosilane and hydrogen, and the target substance comprises trichlorosilane; The distance from the first feed port to the bottom of the fluidized bed reactor is greater than the distance from the second feed port to the bottom of the fluidized bed reactor, the inlet of the fluidized bed reactor is located near the bottom of the fluidized bed reactor, and the outlet of the fluidized bed reactor is located near the top of the fluidized bed reactor.

6. The synthesis equipment of trichlorosilane according to claim 5, characterized in that: The fluidized bed reactor further includes a third feed port for adding silicon powder having a third particle size range, and a fourth feed port for adding silicon powder having a fourth particle size range, wherein the third feed port is located between the first feed port and the second feed port, and the fourth feed port is located near the bottom of the fluidized bed reactor; The synthesis equipment of trichlorosilane also includes: a separator, wherein the inlet of the separator is connected to the outlet of the fluidized bed reactor to obtain the silicon powder in the third particle size range flowing out of the fluidized bed reactor, and the first outlet of the separator is connected to the third feed port; a filter, wherein the inlet of the filter is connected to the second outlet of the separator to obtain the silicon powder in the fourth particle size range flowing out of the separator, and the first outlet of the filter is connected to the fourth feed port; and / or, The fluidized bed reactor has an expansion zone and a non-expansion zone. The expansion zone is located between the outlet of the fluidized bed reactor and the first feed inlet. The diameter of the expansion zone is larger than that of the non-expansion zone.

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