Non-stop maintenance processes and equipment in chlorosilane production

Abstract

This invention relates to a non-stop maintenance process and apparatus for chlorosilane production. The apparatus comprises, in sequence, a hydrogen main, a second switching valve, a hydrogen buffer tank, a ninth switching valve, a hydrogen compressor, a static mixer, a first heat exchanger, a seventh switching valve, a heater, and a fluidized bed reactor. The other inlet of the static mixer is connected in sequence to the STC buffer tank and the tenth switching valve. The first and second ends of the first heat exchanger are respectively connected to the outlet of the static mixer and one end of the seventh switching valve. The third end of the first heat exchanger is connected to subsequent processes via a sixth switching valve, and the second end of the first heat exchanger is connected to subsequent processes via a first branch and a fifth switching valve. This maintenance process and apparatus prevents bed damage and material clogging at the bottom and internal components of the tower during fluidized bed cooling and depressurization, reducing the workload during fluidized bed restart and avoiding personnel entering confined spaces, thus reducing the risk of accidents.

Description

Technical fields:

[0001] This invention relates to a chemical process and equipment, particularly a non-stop maintenance process and apparatus for the production of chlorosilanes. Background technology:

[0002] During the production of chlorosilanes, chemical equipment often requires maintenance. Many containers and pipelines are under high temperature and pressure during the production process, so leaks in containers and pipelines often occur. If a container or a section of pipeline malfunctions, the fluidized bed reactor needs to be cooled and depressurized urgently to stop the feeding of subsequent processes. At this time, the bed of the fluidized bed reactor will be damaged.

[0003] The materials inside a fluidized bed reactor are mainly hydrogen, silicon powder, silicon tetrachloride, and trichlorosilane. Once the reactor is cooled and depressurized, silicon tetrachloride and trichlorosilane will partially condense and wrap with silicon powder to form lumps, thereby damaging the bed. The material will fall to the bottom of the reactor and condense, which will block the distributor and bubble breaker and other internal components of the reactor.

[0004] When restarting the fluidized bed reactor, it is necessary to open the manhole to enter the reactor tower for cleaning. The condensate blocking the bottom of the reactor and the trays needs to be removed before feeding can resume production.

[0005] Meanwhile, during the production of silane and chlorosilane, the reactors, pipelines, and containers are all under high temperature and high pressure. During maintenance, it is necessary to cool down and depressurize. Equipment under high temperature conditions is often in an expanded state. After cooling down, the degree of expansion decreases, and the screws at the pipe and equipment connection will loosen. They need to be tightened as the temperature drops, otherwise it will cause serious accidents such as pipe leakage or crack expansion.

[0006] If a non-stop fluidized bed reactor is selected during maintenance, the generated chlorosilanes can only be discharged to the tail gas tower for treatment. A large amount of chlorosilane products entering the tail gas tower will cause the tail gas tower to operate under overload, creating danger and wasting materials. Summary of the Invention:

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a non-stop maintenance process and device for chlorosilane production. The non-stop maintenance process and device for chlorosilane production is reasonably designed, which avoids the bed layer being damaged during fluidized bed cooling and depressurization, and the material falling and clogging the bottom of the tower and the internal parts of the tower. It greatly reduces the workload when restarting the fluidized bed, and also avoids personnel entering the confined space for operation, thus reducing the risk of accidents.

[0008] This invention is implemented using the following scheme:

[0009] The present invention relates to a non-stop maintenance device for chlorosilane production, characterized in that it comprises a hydrogen main pipe, a second switching valve, a hydrogen buffer tank, a ninth switching valve, a hydrogen compressor, a static mixer, a first heat exchanger, a seventh switching valve, a heater, and a fluidized bed reactor connected in sequence. The other inlet of the static mixer is connected in sequence to the STC buffer tank and the tenth switching valve. The first end and the second end of the first heat exchanger are respectively connected to the outlet of the static mixer and one end of the seventh switching valve. The third end of the first heat exchanger is connected to the subsequent process through the sixth switching valve. The second end of the first heat exchanger is connected to the subsequent process through the first branch and the fifth switching valve.

[0010] The hydrogen main pipe is connected to the first inlet of a gas compressor via a second branch and a first switching valve. The second inlet of the gas compressor is connected to the fourth end of a first heat exchanger via a third branch and a third switching valve and a fourth switching valve connected in series thereon. The outlet of the gas compressor is connected to the inlet of a heater via a fourth branch and an eighth switching valve connected in series thereon.

[0011] The outlet of the fluidized bed reactor is sequentially connected to a first silicon powder filter, a thirteenth switch valve, a second silicon powder filter, and an eleventh switch valve. The outlet of the eleventh switch valve is connected to the pipeline between the third and fourth switch valves after passing through a second heat exchanger. The outlet of the first silicon powder filter is located between the thirteenth switch valve, the second silicon powder filter, and the eleventh switch valve, and a twelfth switch valve is connected in parallel.

[0012] The present invention relates to a non-stop maintenance process in the production of chlorosilanes using the aforementioned apparatus, characterized by: the working method for maintenance and repair of process sections before and after the fluidized bed reactor.

[0013] (1) Close the second, fourth, fifth, seventh, ninth, tenth and twelfth switch valves, and open the first, eighth, thirteenth, eleventh and third switch valves. Hydrogen enters the gas compressor through the first switch valve and the second branch.

[0014] (2) The product in the fluidized bed reactor is filtered by the first silicon powder filter and the second silicon powder filter to remove the silicon powder carried in the gas phase. The gas is cooled to 100-120°C by the second heat exchanger and enters the gas compressor through the third switch valve. The gas phase is pressurized to 1.0-1.5 MPa by the gas compressor and heated to 300-400°C by the heater. The reaction rate of the material in the fluidized bed is reduced by cutting off the feed of silicon tetrachloride and silicon powder to the fluidized bed reactor and by cooling and depressurizing the fluidized bed reactor.

[0015] (3) After the above cycle is established, the back end can start to cool down and depressurize, and the equipment of the downstream process can be cooled down to room temperature. After the replacement is qualified, the inspection and maintenance work can be started. The equipment at the front end of the fluidized bed reactor can also be inspected and maintained.

[0016] (4) After the maintenance work is completed, close the first switch valve to cut off the hydrogen feed to the gas compressor. At the same time, open the second and ninth switch valves. The hydrogen compressor starts up. Simultaneously open the tenth switch valve to introduce STC and hydrogen into the static mixer for mixing. After preheating through the first heat exchanger, the fourth and seventh switch valves open simultaneously, and the third and eighth switch valves close simultaneously. Open the sixth switch valve and close the fifth switch valve. After the material flows normally to the next process, open the twelfth switch valve and close the eleventh and thirteenth switch valves at the same time. Close the second silicon powder filter. The non-stop maintenance process is completed.

[0017] Working procedures for inspecting and maintaining fluidized bed reactors:

[0018] (1) When the fluidized bed needs maintenance, the STC buffer tank is shut down. Hydrogen is compressed by the hydrogen compressor and the pressure drops to 1.0-1.5MPa to maintain the pressure of the downstream process. The hydrogen is introduced into the downstream process through the first branch, the fifth switch valve is opened, and the sixth and seventh switch valves are closed at the same time. The first, third, eighth, eleventh and thirteenth valves are kept closed. If the liquid level of each storage tank in the downstream process drops, the feed pump of the STC buffer tank can be started to transport STC to the downstream process to maintain the stability of the storage tank liquid level.

[0019] (2) At this time, the fluidized bed reactor can be cooled and depressurized for inspection and maintenance.

[0020] (3) After the inspection and maintenance work is completed, open the fourth and seventh switch valves. When the fluidized bed reactor bed is established and the temperature and pressure are under normal operating conditions, open the sixth switch valve and simultaneously close the fifth switch valve to introduce the product into the next process.

[0021] (4) That is, the process is completed.

[0022] This invention keeps the fluidized bed running during maintenance, thus avoiding damage to the bed layer and material clogging the bottom and internal components of the tower when the fluidized bed is cooled and depressurized. This greatly reduces the workload when restarting the fluidized bed and also avoids personnel entering confined spaces, reducing the risk of accidents.

[0023] At the same time, it avoids the frequent cold tightening of bolts at equipment and pipeline connections during cooling and pressure reduction, reduces metal fatigue of bolts, and thus improves the strength of equipment and pipeline connections.

[0024] After establishing a bypass circulation in the fluidized bed, the material reaction efficiency is reduced to a minimum. The generated material is repeatedly circulated in the fluidized bed through the bypass circulation, avoiding a large amount of chlorosilane from entering the tail gas tower for treatment and reducing the load on the tail gas tower.

[0025] The present invention provides a process route scheme for overhauling fluidized bed reactors. By using a cross-line connection, materials such as STC and hydrogen are bypassed from the fluidized bed reactor and delivered to the next process stage. This avoids the problem of subsequent processes also shutting down when the fluidized bed reactor is shut down, thereby reducing maintenance work when restarting. After the overhaul is completed, the blind flange and valves can be removed, and production can be resumed immediately, saving a significant amount of time and materials. Attached image description:

[0026] The present invention will be further described below with reference to the accompanying drawings;

[0027] Figure 1 This is a schematic diagram of the working principle of existing chlorosilane production;

[0028] Figure 2 This is a schematic diagram illustrating the working principle of the device of the present invention;

[0029] Figure 3-5 This is a schematic diagram illustrating the working principle of the device of the present invention under different working conditions. Detailed implementation method:

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, the non-stop maintenance device in the production of chlorosilane of the present invention includes a hydrogen main pipe A1, a second switch valve 2, a hydrogen buffer tank A2, a ninth switch valve 9, a hydrogen compressor A3, a static mixer A4, a first heat exchanger A5, a seventh switch valve 7, a heater A6, and a fluidized bed reactor A7 connected in sequence. The other inlet end of the static mixer A4 is connected in sequence to the STC buffer tank A8 and the tenth switch valve 10. The first end and the second end of the first heat exchanger are respectively connected to the outlet end of the static mixer A4 and one end of the seventh switch valve 7. The third end of the first heat exchanger is connected to the subsequent process A9 through the sixth switch valve 6. The second end of the first heat exchanger is connected to the subsequent process A9 through the first branch A10 and the fifth switch valve 5.

[0032] The hydrogen main pipe A1 is connected to the first inlet of a gas compressor A12 via the second branch A11 and the first switch valve 1. The second inlet of the gas compressor A12 is connected to the fourth end of the first heat exchanger via the third branch A13 and the third switch valve 3 and the fourth switch valve 4 connected in series thereon. The outlet of the gas compressor is connected to the inlet of the heater A6 via the fourth branch A14 and the eighth switch valve 8 connected in series thereon.

[0033] The outlet of the fluidized bed reactor A7 is sequentially connected to the first silicon powder filter A15, the thirteenth switch valve 13, the second silicon powder filter A16, and the eleventh switch valve 11. The outlet of the eleventh switch valve 11 is connected to the pipeline between the third switch valve 3 and the fourth switch valve 4 after passing through the second heat exchanger A17. The outlet of the first silicon powder filter A15, located between the thirteenth switch valve 13, the second silicon powder filter A16, and the eleventh switch valve 11, is connected in parallel to the twelfth switch valve 12.

[0034] This invention relates to a non-stop maintenance process in the production of chlorosilanes using the aforementioned apparatus, specifically a method for performing maintenance on the process sections before and after the fluidized bed reactor.

[0035] (1) Close the second, fourth, fifth, seventh, ninth, tenth and twelfth switch valves, and open the first, eighth, thirteenth, eleventh and third switch valves. Hydrogen enters the gas compressor through the first switch valve and the second branch.

[0036] (2) The product in the fluidized bed reactor is filtered by two filters, the first silicon powder filter A15 and the second silicon powder filter A16, to remove the silicon powder carried in the gas phase. The gas is cooled to 100-120°C by the second heat exchanger A17 and enters the gas compressor through the third switch valve 3. The gas phase is pressurized to 1.0-1.5 MPa by the gas compressor A12 and heated to 300-400°C by the heater A6. The reaction rate of the material in the fluidized bed is reduced by cutting off the feed of silicon tetrachloride and silicon powder to the fluidized bed reactor and by cooling and depressurizing the fluidized bed reactor. Through the established circulation, the fluidized bed reactor can be kept running without stopping at a very low cost, avoiding the internal silicon powder from collapsing due to the destruction of the bed and making it difficult to restart the reactor. The main purpose of opening the eleventh and thirteenth switch valves and activating the second silicon powder filter is to remove silicon powder as much as possible, prevent silicon powder from entering the gas compressor, and ensure the service life of the gas compressor.

[0037] (3) After the above cycle is established, the downstream equipment can begin to cool and depressurize, bringing it down to room temperature. After the equipment is replaced and deemed qualified, maintenance and repair work can begin. Maintenance and repair work can also be carried out on the equipment at the front end of the fluidized bed reactor (e.g., Figure 3 As shown, the dashed lines represent pipeline routes, and the solid lines represent blocked routes.

[0038] (4) After the maintenance work is completed, close the first switch valve to cut off the hydrogen feed to the gas compressor. At the same time, open the second and ninth switch valves to start the hydrogen compressor. Simultaneously open the tenth switch valve to introduce STC and hydrogen into the static mixer for mixing. After preheating through the first heat exchanger A5, the fourth switch valve 4 and the seventh switch valve 7 are opened simultaneously, and the third switch valve 3 and the eighth switch valve 8 are closed simultaneously. Open the sixth switch valve 6 and close the fifth switch valve 5. After the material flows normally to the next process, open the twelfth switch valve 12 and simultaneously close the eleventh switch valve 11 and the thirteenth switch valve 13. Close the second silicon powder filter A16, thus completing the non-stop maintenance process (e.g. Figure 4 As shown, the dashed lines represent pipeline routes, and the solid lines represent blocked routes.

[0039] Working procedures for inspecting and maintaining fluidized bed reactors:

[0040] (1) When the fluidized bed needs maintenance, the STC buffer tank is shut down. Hydrogen is compressed by the hydrogen compressor and the pressure drops to 1.0-1.5MPa to maintain the pressure of the downstream process. The hydrogen is introduced into the downstream process through the first branch A10, the fifth switch valve 5 is opened, and the sixth and seventh switch valves are closed at the same time. The first, third, eighth, eleventh and thirteenth valves are kept closed. If the liquid level of each storage tank in the downstream process drops, the feed pump of the STC buffer tank can be started to transport STC to the downstream process to maintain the stability of the storage tank liquid level.

[0041] (2) At this time, the fluidized bed reactor can be cooled and depressurized for inspection and maintenance.

[0042] (3) After the inspection and maintenance work is completed, open the fourth and seventh switch valves. When the fluidized bed reactor bed is established and the temperature and pressure are under normal operating conditions, open the sixth switch valve and simultaneously close the fifth switch valve to introduce the product into the next process (restore to normal). Figure 3 (as shown)

[0043] (4) That is, the process is completed.

[0044] This invention keeps the fluidized bed running during maintenance, thus avoiding damage to the bed layer and material clogging the bottom and internal components of the tower when the fluidized bed is cooled and depressurized. This greatly reduces the workload when restarting the fluidized bed and also avoids personnel entering confined spaces, reducing the risk of accidents.

[0045] At the same time, it avoids the frequent cold tightening of bolts at equipment and pipeline connections during cooling and pressure reduction, reduces metal fatigue of bolts, and thus improves the strength of equipment and pipeline connections.

[0046] After establishing a bypass circulation in the fluidized bed, the material reaction efficiency is reduced to a minimum. The generated material is repeatedly circulated in the fluidized bed through the bypass circulation, avoiding a large amount of chlorosilane from entering the tail gas tower for treatment and reducing the load on the tail gas tower.

[0047] The present invention provides a process route scheme for overhauling fluidized bed reactors. By using a cross-line connection, materials such as STC and hydrogen are bypassed from the fluidized bed reactor and delivered to the next process stage. This avoids the problem of subsequent processes also shutting down when the fluidized bed reactor is shut down, thereby reducing maintenance work when restarting. After the overhaul is completed, the blind flange and valves can be removed, and production can be resumed immediately, saving a significant amount of time and materials.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A non-stop maintenance process for chlorosilane production, characterized in that: The system includes a hydrogen main pipe, a second switching valve, a hydrogen buffer tank, a ninth switching valve, a hydrogen compressor, a static mixer, a first heat exchanger, a seventh switching valve, a heater, and a fluidized bed reactor, connected in sequence. The other inlet of the static mixer is connected in sequence to the STC buffer tank and the tenth switching valve. The first and second ends of the first heat exchanger are respectively connected to the outlet of the static mixer and one end of the seventh switching valve. The third end of the first heat exchanger is connected to the subsequent process via the sixth switching valve. The second end of the first heat exchanger is connected to the subsequent process via the first branch and the fifth switching valve. The hydrogen main pipe is connected to the first inlet of a gas compressor via a second branch and a first switching valve. The second inlet of the gas compressor is connected to the fourth end of a first heat exchanger via a third branch and a third switching valve and a fourth switching valve connected in series thereon. The outlet of the gas compressor is connected to the inlet of a heater via a fourth branch and an eighth switching valve connected in series thereon. The outlet of the fluidized bed reactor is sequentially connected to a first silicon powder filter, a thirteenth switch valve, a second silicon powder filter, and an eleventh switch valve. The outlet of the eleventh switch valve is connected to the pipeline between the third switch valve and the fourth switch valve after passing through a second heat exchanger. The outlet of the first silicon powder filter is located between the thirteenth switch valve, the second silicon powder filter, and the eleventh switch valve, and a twelfth switch valve is connected in parallel. Working methods for inspecting and maintaining the process sections before and after a fluidized bed reactor: (1) Close the second, fourth, fifth, seventh, ninth, tenth and twelfth switch valves, and open the first, eighth, thirteenth, eleventh and third switch valves. Hydrogen enters the gas compressor through the first switch valve and the second branch. (2) The product in the fluidized bed reactor is filtered by the first silicon powder filter and the second silicon powder filter to remove the silicon powder carried in the gas phase. The gas is cooled to 100-120°C by the second heat exchanger and enters the gas compressor through the third switch valve. The gas phase is pressurized to 1.0-1.5 MPa by the gas compressor and heated to 300-400°C by the heater. The reaction rate of the material in the fluidized bed is reduced by cooling and depressurizing the silicon tetrachloride and silicon powder in the fluidized bed reactor. That is, the reaction rate of the material in the fluidized bed is reduced by cutting off the feed of silicon tetrachloride and silicon powder to the fluidized bed reactor and cooling and depressurizing the fluidized bed reactor. (3) After the above cycle is established, the back end can start to cool down and depressurize, and the equipment of the downstream process can be cooled down to room temperature. After the replacement is qualified, the inspection and maintenance work can be started. The equipment at the front end of the fluidized bed reactor can also be inspected and maintained. (4) After the maintenance work is completed, close the first switch valve to cut off the hydrogen feed to the gas compressor. At the same time, open the second and ninth switch valves. The hydrogen compressor starts up. Simultaneously open the tenth switch valve to introduce STC and hydrogen into the static mixer for mixing. After preheating through the first heat exchanger, the fourth and seventh switch valves open simultaneously, and the third and eighth switch valves close simultaneously. Open the sixth switch valve and close the fifth switch valve. After the material flows normally to the next process, open the twelfth switch valve and close the eleventh and thirteenth switch valves at the same time. Close the second silicon powder filter. The non-stop maintenance process is completed.

2. The non-stop maintenance process in chlorosilane production according to claim 1, characterized in that: Working procedures for inspecting and maintaining fluidized bed reactors: (1) When the fluidized bed needs maintenance, the STC buffer tank is shut down. Hydrogen is compressed by the hydrogen compressor and the pressure drops to 1.0-1.5MPa to maintain the pressure of the downstream process. The hydrogen is introduced into the downstream process through the first branch, the fifth switch valve is opened, and the sixth and seventh switch valves are closed at the same time. The first, third, eighth, eleventh and thirteenth valves are kept closed. If the liquid level of each storage tank in the downstream process drops, the feed pump of the STC buffer tank can be started to transport STC to the downstream process to maintain the stability of the storage tank liquid level. (2) At this time, the fluidized bed reactor can be cooled and depressurized for inspection and maintenance. (3) After the inspection and maintenance work is completed, open the fourth and seventh switch valves. When the fluidized bed reactor bed is established and the temperature and pressure are under normal operating conditions, open the sixth switch valve and simultaneously close the fifth switch valve to introduce the product into the next process. (4) That is, the process is completed.

Images