Online silicon powder adding system

Abstract

According to the online silicon powder adding system, the bottom end of a low-pressure hopper is connected with the top end of a high-pressure hopper, a low-pressure hopper filter and a silicon powder conveying pipe are installed at the top end of the low-pressure hopper, and an emptying pipe is arranged at the top end of the low-pressure hopper filter; the top end of the high-pressure hopper is connected with the high-pressure hopper filter, the lower end of the high-pressure hopper is connected with the reactor, and the top end of the high-pressure hopper filter is provided with a blow-down pipe; the nitrogen conveying pipe is respectively connected to the bottom of the low-pressure hopper, a connecting pipe of the high-pressure hopper and the reactor, the upper part of the low-pressure hopper filter, the upper part of the high-pressure hopper filter and a connecting pipe of the low-pressure hopper and the high-pressure hopper; the hydrogen conveying pipe is respectively connected to a connecting pipe of the high-pressure hopper and the high-pressure hopper filter, and the nitrogen conveying pipe is arranged on a connecting pipe of the high-pressure hopper and the reactor. Therefore, the technical problems of incomplete replacement of the silicon powder and poor product quality can be solved.

Description

Technical Field

[0001] The utility model relates to the field of machinery, in particular to an online silicon powder adding system. Background Art

[0002] This system involves online addition of silicon powder to a fluidized bed reactor used in trichlorosilane synthesis. A fluidized bed reactor is a device where gases undergo a chemical reaction within a fluidized bed of solid material or catalyst. Silicon powder used to synthesize trichlorosilane is used as the feed material in the reactor. Trichlorosilane, a type of chlorosilane, is produced by a high-temperature reaction of silicon powder, hydrogen, and silicon tetrachloride in a fluidized bed reactor.

[0003] During the implementation of the present invention, it was found that the existing replacement of silicon powder was not very thorough, and impurities such as moisture and air might enter the reactor, which had a certain impact on product quality. Utility Model Content

[0004] In view of this, the embodiment of the present invention provides a silicon powder online adding system, which can solve the technical problems of incomplete silicon powder replacement and poor product quality.

[0005] To achieve the above-mentioned purpose, according to an embodiment of the present invention, a silicon powder online adding system is provided, comprising a low-pressure hopper, a low-pressure hopper filter, a high-pressure hopper, a high-pressure hopper filter, a hydrogen delivery pipe and a nitrogen delivery pipe; wherein, the bottom end of the low-pressure hopper is connected to the top end of the high-pressure hopper, and a low-pressure hopper filter and a silicon powder delivery pipe are installed at the top end of the low-pressure hopper, and a vent pipe is provided at the top end of the low-pressure hopper filter; the top end of the high-pressure hopper is connected to the high-pressure hopper filter, and the lower end of the high-pressure hopper is connected to the reactor, and a vent pipe is provided at the top end of the high-pressure hopper filter; the nitrogen delivery pipe is respectively connected to the bottom of the low-pressure hopper, the connecting pipe between the high-pressure hopper and the reactor, the upper part of the low-pressure hopper filter, the upper part of the high-pressure hopper filter, and the connecting pipe between the low-pressure hopper and the high-pressure hopper; the hydrogen delivery pipe is respectively connected to the connecting pipe between the high-pressure hopper and the high-pressure hopper filter, and the nitrogen delivery pipe installed on the connecting pipe between the high-pressure hopper and the reactor.

[0006] Optionally, the method includes installing a differential pressure gauge on the low-pressure hopper filter and the high-pressure hopper filter respectively.

[0007] Optionally, it includes: installing a low-pressure hopper high material level alarm and a low-pressure hopper low material level alarm on the upper part and the lower part of the low-pressure hopper respectively, and installing a high-pressure hopper low material level alarm on the high-pressure hopper.

[0008] Optionally, the method includes: installing pressure gauges on the high-pressure hopper and the connecting pipe between the high-pressure hopper and the reactor.

[0009] Optionally, the nitrogen delivery pipe connected to the bottom end of the low-pressure hopper is designed as a double delivery pipe, and the double delivery pipes are respectively connected to both sides of the bottom end of the low-pressure hopper.

[0010] Optionally, it includes: three shut-off valves are sequentially installed on the connecting pipe between the bottom end of the low-pressure hopper and the top end of the high-pressure hopper, and a nitrogen delivery pipe is connected between the two shut-off valves close to the low-pressure hopper.

[0011] Optionally, the method includes installing a shut-off valve on a nitrogen delivery pipe connected between two shut-off valves close to the low-pressure hopper.

[0012] Optionally, it includes: a vent pipe is provided between two shut-off valves close to the high-pressure hopper, and a shut-off valve is installed on the vent pipe.

[0013] Optionally, the method includes: installing two shut-off valves in sequence on the connecting pipe between the high-pressure hopper and the reactor, and installing a shut-off valve on the nitrogen delivery pipe connected to the connecting pipe between the high-pressure hopper and the reactor.

[0014] Optionally, the method includes: a regulating valve being installed on the hydrogen delivery pipe connected to the connecting pipe between the high-pressure hopper and the high-pressure hopper filter, and a pressure reducing valve being installed on the hydrogen delivery pipe connected to the nitrogen delivery pipe.

[0015] One embodiment of the above-mentioned utility model has the following advantages or beneficial effects: the silicon powder online addition system provided by the utility model can achieve thorough replacement of the silicon powder to be added to the reactor by first replacing the silicon powder with nitrogen and then replacing it again with the material participating in the reaction (hydrogen), ensuring that the moisture, air, nitrogen, etc. in the silicon powder are completely replaced before entering the fluidized bed reactor under the promotion of hydrogen to participate in the synthesis of trichlorosilane; and, the impurity content in the silicon powder participating in the reaction is greatly reduced, thereby ensuring system safety, reducing the generation of by-products, and improving product quality.

[0016] The further effects of the above-mentioned non-conventional optional manner will be described below in conjunction with specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are provided to facilitate a better understanding of the present invention and do not constitute an undue limitation of the present invention.

[0018] Figure 1 It is a structural schematic diagram of a silicon powder online adding system according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0019] The following description of exemplary embodiments of the present invention is made in conjunction with the accompanying drawings, which include various details of the embodiments of the present invention to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0020] At least one embodiment of the present invention provides a silicon powder online addition system, which can be used not only for online addition of silicon powder in the reaction of synthesizing trichlorosilane, but also for online addition of raw materials and auxiliary materials in the production of other hazardous chemicals. Figure 1 As shown, the silicon powder online addition system may include a low-pressure hopper 1, a high-pressure hopper 2, a low-pressure hopper filter 3, a high-pressure hopper filter 4, a silicon powder delivery pipe 5, a nitrogen delivery pipe 6, a hydrogen delivery pipe 7, and a vent pipe 8. The low-pressure hopper 1 is used to determine the mass of silicon powder added to the reactor, the high-pressure hopper 2 is used to completely displace impurities in the silicon powder before feeding it into the reactor for trichlorosilane synthesis, the low-pressure hopper filter 3 is used to collect silicon powder that escapes during the addition process, and the high-pressure hopper filter 4 is used to collect silicon powder that escapes during the displacement process. The nitrogen in the nitrogen delivery pipe 6 is an inert gas used to displace air and moisture that may be entrained in the silicon powder. The hydrogen in the hydrogen delivery pipe 7 is used to displace air, moisture, and nitrogen that may be entrained in the silicon powder and deliver the silicon powder to the reactor.

[0021] In the embodiment, the bottom end 1 of the low-pressure hopper is connected to the top end of the high-pressure hopper 2, and a low-pressure hopper filter 3 and a silicon powder conveyor 5 are installed at the top end of the low-pressure hopper 1. A vent pipe 8 is provided at the top end of the low-pressure hopper filter 3. The top end of the high-pressure hopper 2 is connected to the high-pressure hopper filter 4, and the lower end of the high-pressure hopper 2 is connected to the reactor. A vent pipe 8 is provided at the top end of the high-pressure hopper filter 4. A nitrogen delivery pipe 6 is respectively connected to the bottom of the low-pressure hopper 1, the connecting pipe between the high-pressure hopper 2 and the reactor, the upper part of the low-pressure hopper filter 3, the upper part of the high-pressure hopper filter 4, and the connecting pipe between the low-pressure hopper 1 and the high-pressure hopper 2. A hydrogen delivery pipe 7 is respectively connected to the connecting pipe between the high-pressure hopper 2 and the high-pressure hopper filter 4, and the nitrogen delivery pipe 6 installed on the connecting pipe between the high-pressure hopper 2 and the reactor.

[0022] It should be noted that the low-pressure hopper filter 2 and high-pressure hopper filter 4 are capable of collecting and recycling silicon powder that escapes during the process, thereby reducing material loss. In addition, the nitrogen delivery pipe 6 connected to the low-pressure hopper filter 2 and the high-pressure hopper filter 4 can be purged with pulsed nitrogen, eliminating the need to wait for the pressure differential to increase before backflushing.

[0023] It can be seen that the silicon powder online addition system described in the embodiment can ensure the quality of the silicon powder fed into the reactor, reduce the possibility of impurities such as moisture, air, and nitrogen entering the reactor, ensure system safety, reduce the generation of by-products, and improve product quality.

[0024] In a further embodiment, the nitrogen delivery pipe 6 connected to the bottom of the low-pressure hopper 1 is designed as a double delivery pipe, and the double delivery pipes are respectively connected to the two sides of the bottom of the low-pressure hopper 1 (see Figure 1 ).

[0025] In some further embodiments, a regulating valve 14 is installed on the hydrogen delivery pipe 7 connected to the connecting pipe between the high-pressure hopper 2 and the high-pressure hopper filter 4 to control the pressure of the hydrogen entering the high-pressure hopper 2. And a pressure reducing valve 15 is installed on the hydrogen delivery pipe 7 connected to the nitrogen delivery pipe 6 (the nitrogen delivery pipe 6 installed on the connecting pipe between the high-pressure hopper 2 and the reactor) to control the hydrogen purge pressure entering the high-pressure hopper.

[0026] In addition, a shut-off valve 13 is installed on the vent pipe 8 at the top of the high-pressure hopper filter 4, so that the purge exhaust gas can be controlled.

[0027] As some preferred embodiments of the present invention, Figure 1 As shown, the silicon powder online adding system described in the present invention is respectively equipped with a differential pressure gauge 9 on the low-pressure hopper filter 2 and the high-pressure hopper filter 4, exemplified as: a low-pressure hopper filter differential pressure gauge and a high-pressure hopper filter differential pressure gauge.

[0028] Furthermore, a low-pressure hopper high-level alarm 10 and a low-pressure hopper low-level alarm 11 are installed at the upper and lower parts of the low-pressure hopper 1, respectively. Therefore, the mass of the silicon powder fed into the reactor is determined using these alarms. A weighing device can also be added before the low-pressure hopper 1 for more accurate measurement. A high-pressure hopper low-level alarm 16 is also installed on the high-pressure hopper 2.

[0029] In addition, pressure gauges 12 are installed on the high-pressure hopper 2 and the connecting pipe between the high-pressure hopper 2 and the reactor, for example: a high-pressure hopper pressure gauge and a reactor pressure gauge.

[0030] As other preferred embodiments of the present invention, Figure 1 As shown, the silicon powder online addition system of the present invention has three shut-off valves 13 installed in sequence on the connecting pipes at the bottom of the low-pressure hopper 1 and the top of the high-pressure hopper 2, thereby controlling the feed from the low-pressure hopper 1 to the high-pressure hopper 3. Furthermore, a nitrogen delivery pipe 6 is connected between the two shut-off valves 13 near the low-pressure hopper 1.

[0031] In a further embodiment, a shutoff valve 13 is installed on the nitrogen delivery pipe 6 connected between the two shutoff valves 13 near the low-pressure hopper 1, thereby controlling the nitrogen purge. In addition, a vent pipe 8 is provided between the two shutoff valves 13 near the high-pressure hopper 2, and a shutoff valve 13 is installed on the vent pipe 8, thereby controlling the purge of the exhaust gas.

[0032] As some more preferred embodiments of the present invention, Figure 1 As shown, two shut-off valves 13 are sequentially installed on the connecting pipe between the high-pressure hopper 2 and the reactor of the silicon powder online addition system of the present invention, thereby controlling the feed of the high-pressure hopper 2 to the reactor. Furthermore, a shut-off valve 13 is installed on the nitrogen delivery pipe 6 connected to the connecting pipe between the high-pressure hopper 2 and the reactor, thereby controlling the nitrogen purge.

[0033] For example, in the initial state of the silicon powder online addition system of the present invention, all valves are closed, and there is no silicon powder in the low-pressure hopper 1 and the high-pressure hopper 2, that is, the tank is empty. The low-pressure hopper 1 is in a low material level alarm (the low-pressure hopper low material level alarm 11 alarms, and the low-pressure hopper high material level alarm 10 is normal), and the high-pressure hopper 2 is in a low material level alarm (the high-pressure hopper low material level alarm 16 alarms). The pressure gauge 12 installed on the connecting pipe between the high-pressure hopper 2 and the reactor is about 3Mpag. The treated silicon powder is added to the low-pressure hopper 1 through the silicon powder conveying pipe 5. When the low-pressure hopper high material level alarm 10 alarms, the silicon powder addition is stopped. At this time, a fixed amount of silicon powder is stored in the low-pressure hopper 1, and the conditions for adding high-pressure hopper 2 are met.

[0034] After opening the shut-off valve 13 on the connecting pipe between the high-pressure hopper 2 and the high-pressure hopper filter 4, and the shut-off valve 13 installed on the vent pipe 8 at the top of the high-pressure hopper filter 4, open the three shut-off valves 13 installed in sequence on the connecting pipe between the bottom of the low-pressure hopper 1 and the top of the high-pressure hopper 2 (the opening order can start from the shut-off valve 13 near the top of the high-pressure hopper 2). Transfer the silicon powder in the low-pressure hopper 1 to the high-pressure hopper 2 by gravity. During the addition process, the low-pressure hopper high-level alarm 10 returns to normal until the low-pressure hopper low-level alarm 11 alarms and remains for 2 minutes. Close the shut-off valve 13 near the low-pressure hopper 1 on the connecting pipe between the bottom of the low-pressure hopper 1 and the top of the high-pressure hopper 2, open the middle shut-off valve 13 on the connecting pipe between the bottom of the low-pressure hopper 1 and the top of the high-pressure hopper 2, and blow the silicon powder in the pipeline to the high-pressure hopper 2 for 1 minute. Close the shut-off valve 13 on the connecting pipe between the bottom of the low-pressure hopper 1 and the top of the high-pressure hopper 2, which is close to the high-pressure hopper 2. Open the shut-off valve 13 on the vent pipe 8 provided between the two shut-off valves close to the high-pressure hopper 2, and blow the remaining silicon powder in the pipeline to a safe place for discharge.

[0035] Close the shutoff valve 13 on the vent pipe 8 between the two shutoff valves near high-pressure hopper 2, the middle shutoff valve 13 on the pipe connecting the bottom of low-pressure hopper 1 to the top of high-pressure hopper 2, and the shutoff valve 13 installed on the nitrogen delivery pipe 6 connecting the two shutoff valves near low-pressure hopper 1 in sequence. At this point, the silicon powder in low-pressure hopper 1 has been completely transferred to high-pressure hopper 2, and the high-pressure hopper low-level alarm 16 has returned to normal during the silicon powder delivery process. Open the shutoff valve 13 on the nitrogen delivery pipe 6 installed on the pipe connecting high-pressure hopper 2 to the reactor, and purge high-pressure hopper 2 and related pipelines with nitrogen to replace moisture and air in the system. The replacement time should be no less than 2 minutes.

[0036] Close the shut-off valve 13 on the nitrogen delivery pipe 6 installed on the connecting pipe between the high-pressure hopper 2 and the reactor. When the pressure of the pressure reducing valve 15 drops to about 30 kpag, close the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4, open the pressure reducing valve 15, and decompress the high-pressure hydrogen. The high-pressure hopper 2 is pressurized to 0.3-0.4 MPag (monitored by the instrument 5) by the decompressed hydrogen. Close the pressure reducing valve 15, open the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4, and perform the first hydrogen replacement.

[0037] When the pressure of the pressure gauge 12 installed on the high-pressure hopper 2 drops to about 30 kpag, close the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4, open the pressure reducing valve 15, and decompress the high-pressure hydrogen. The high-pressure hopper 2 is pressurized to 0.3-0.4 Mpag by the decompressed hydrogen (monitored by the pressure gauge 12 installed on the high-pressure hopper 2), close the pressure reducing valve 15, and open the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4 to perform a second hydrogen replacement.

[0038] When the pressure gauge 12 installed on the high-pressure hopper 2 drops to about 30 kPag, close the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4, open the pressure reducing valve 15, reduce the pressure of the high-pressure hydrogen, and use the reduced-pressure hydrogen to increase the pressure of the high-pressure hopper 2 to 0.3-0.4 MPag (monitored by the instrument 5), and close the pressure reducing valve 15. Open the regulating valve 14 and use the high-pressure hydrogen to increase the pressure of the high-pressure hopper 2. When the pressure gauge 12 installed on the high-pressure hopper 2 is about 0.2 MPag higher than the pressure gauge 12 installed on the connecting pipe between the high-pressure hopper 2 and the reactor, open the two shut-off valves 13 on the connecting pipe between the high-pressure hopper 2 and the reactor in sequence (open the shut-off valve closest to the reactor first), and transport the replaced silicon powder in the high-pressure hopper 2 to the reactor through hydrogen. During this process, control the opening of the regulating valve 14 to keep the pressure in the high-pressure hopper 2 always about 0.2 MPag higher than the pressure in the reactor.

[0039] When the high-pressure hopper low-level alarm 16 sounds and the pressure on the pressure gauge 12 installed on the connecting pipe between the high-pressure hopper 2 and the reactor rises rapidly, close the two shut-off valves 13 on the connecting pipe between the high-pressure hopper 2 and the reactor in sequence (the order is to close the shut-off valve near the high-pressure hopper 2 first), and close the regulating valve 14. Open the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4 to release the high-pressure hydrogen in the high-pressure hopper 2 to a safe place. When the pressure gauge 12 installed on the high-pressure hopper 2 shows a pressure of approximately 30 MPag, open valve 6 and replace the hydrogen in the high-pressure hopper 2 with nitrogen for 2 minutes. Close the shut-off valve 13 on the nitrogen delivery pipe 6 installed on the connecting pipe between the high-pressure hopper 2 and the reactor. When the pressure in the high-pressure hopper 2 reaches approximately 30 kPag (monitored by instrument 5), close the shut-off valve 13 on the connecting pipe between the high-pressure hopper 2 and the high-pressure hopper filter 4 and the shut-off valve 13 on the vent pipe 8 at the top of the high-pressure hopper filter 4. At this point, the process of adding silicon powder to the reactor through low-pressure hopper 1 and high-pressure hopper 2 is complete, and the process returns to step 1 for the next silicon powder addition. When the pressure difference on the differential pressure gauge 9 on low-pressure hopper filter 2 and high-pressure hopper filter 4 increases, nitrogen can be injected into low-pressure hopper filter 3 and high-pressure hopper filter 4 to backflush them and recover the silicon powder adsorbed on the filters.

[0040] It should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" in this utility model may refer to fixed connection, detachable connection, or integral connection. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0041] The above specific embodiments do not limit the scope of protection of this utility model. Those skilled in the art will understand that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model shall be included in the scope of protection of this utility model.

Claims

1. A silicon powder online adding system, characterized in that: It includes a low-pressure hopper, a low-pressure hopper filter, a high-pressure hopper, a high-pressure hopper filter, a hydrogen delivery pipe and a nitrogen delivery pipe; Among them, the bottom end of the low-pressure hopper is connected to the top end of the high-pressure hopper, and a low-pressure hopper filter and a silicon powder conveying pipe are installed on the top end of the low-pressure hopper, and a vent pipe is provided on the top end of the low-pressure hopper filter; the top end of the high-pressure hopper is connected to the high-pressure hopper filter, and the lower end of the high-pressure hopper is connected to the reactor, and a vent pipe is provided on the top end of the high-pressure hopper filter; The nitrogen delivery pipes are respectively connected to the bottom of the low-pressure hopper, the connecting pipe between the high-pressure hopper and the reactor, the upper part of the low-pressure hopper filter, the upper part of the high-pressure hopper filter, and the connecting pipe between the low-pressure hopper and the high-pressure hopper; The hydrogen delivery pipe is respectively connected to the connecting pipe between the high-pressure hopper and the high-pressure hopper filter, and the nitrogen delivery pipe is installed on the connecting pipe between the high-pressure hopper and the reactor.

2. The silicon powder online adding system according to claim 1, characterized in that: include: Differential pressure gauges are installed on the low-pressure hopper filter and the high-pressure hopper filter respectively.

3. The silicon powder online adding system according to claim 1, characterized in that: include: A low-pressure hopper high material level alarm and a low-pressure hopper low material level alarm are respectively installed on the upper part and the lower part of the low-pressure hopper, and a high-pressure hopper low material level alarm is installed on the high-pressure hopper.

4. The silicon powder online adding system according to claim 1, characterized in that: include: Pressure gauges are respectively installed on the high-pressure hopper and the connecting pipe between the high-pressure hopper and the reactor.

5. The silicon powder online adding system according to claim 1, characterized in that: include: The nitrogen delivery pipe connected to the bottom end of the low-pressure hopper is designed as a double delivery pipe, and the double delivery pipes are respectively connected to both sides of the bottom end of the low-pressure hopper.

6. The silicon powder online adding system according to claim 1, characterized in that: include: Three shut-off valves are sequentially installed on the connecting pipe between the bottom of the low-pressure hopper and the top of the high-pressure hopper, and a nitrogen delivery pipe is connected between the two shut-off valves close to the low-pressure hopper.

7. The silicon powder online adding system according to claim 6, characterized in that: include: A shut-off valve is installed on the nitrogen delivery pipe connected between the two shut-off valves near the low-pressure hopper.

8. The silicon powder online adding system according to claim 6, characterized in that: include: A vent pipe is provided between the two shut-off valves close to the high-pressure hopper, and a shut-off valve is installed on the vent pipe.

9. The silicon powder online adding system according to claim 1, characterized in that: include: Two shut-off valves are sequentially installed on the connecting pipe between the high-pressure hopper and the reactor, and a shut-off valve is installed on the nitrogen delivery pipe connected to the connecting pipe between the high-pressure hopper and the reactor.

10. The silicon powder online adding system according to any one of claims 1 to 9, characterized in that: include: A regulating valve is installed on the hydrogen delivery pipe connected to the connecting pipe of the high-pressure hopper and the high-pressure hopper filter, and a pressure reducing valve is installed on the hydrogen delivery pipe connected to the nitrogen delivery pipe.

Images