Organosilicon monomer synthesis aggregate and return device and process

Abstract

The invention discloses an organic silicon monomer synthesis material collecting and returning device and process. A gas phase outlet in the top of a fluidized bed is connected with an inlet of a secondary cyclone separator; a gas phase outlet of the second-stage cyclone separator is connected with an inlet of the third-stage cyclone separator, and a solid phase outlet of the second-stage cyclone separator is connected with a receiving hopper of the second-stage cyclone separator; a receiving hopper of the secondary cyclone separator is connected with inlets of the fine powder tank A and the fine powder tank B; silicon powder and chloromethane react in the fluidized bed, most of silicon powder is separated through a built-in cyclone separator and directly returns to the bed through a dipleg, other gas-solid mixtures enter a secondary cyclone to collect fine powder, the fine powder is alternately and continuously returned to the bed, and the efficiency of the secondary cyclone is adjustable. The reaction of the fluidized bed is stabilized, the automation level and intrinsic safety of the device are improved, and the labor intensity is greatly reduced.

Description

Technical Field

[0001] The invention relates to a process and a device for producing an organosilicon monomer, and belongs to the technical field of organosilicon production. Background Art

[0002] Organic silicon materials are a new type of material that has only been developed in recent decades. They are mainly divided into four categories: silicone rubber, silicone oil, silane coupling agent, and silicone resin. They are widely used in aerospace, pharmaceutical engineering, machinery manufacturing and other industries. At present, the industrial production of organic silicon monomers adopts a direct synthesis process, that is, methyl chloride and silicon powder react in a fluidized bed reactor in a gas-solid phase, and the reaction product is recovered by a cyclone separator. Most of the silicon powder is then separated and purified in the back system. Domestic monomer fluidized bed synthesis technology generally adopts an external multi-stage cyclone, and the fine powder is intermittently returned to the bed. That is, the first-stage cyclone recovers fine powder and is discharged to the fine powder tank through a hopper. The silicon powder in the fine powder tank is returned to the bed through weight loss measurement at a certain interval (5min-30min). The second-stage cyclone recovers fine powder and is discharged to the fine powder tank through a hopper. The silicon powder in the fine powder tank is returned to the bed through weight loss measurement at a certain interval (20min-60min), and so on to the third-stage cyclone and the fourth-stage cyclone. The latter two cyclones return the collected ultrafine powder to the bed or discharge it externally according to the situation.

[0003] In the traditional material collection and recycling process, the first-level cyclone basically needs to recover 80%-95% of the silicon powder brought out of the fluidized bed. The recycling operation is frequent and intensive, and the intermittent return of a large amount of fine powder to the bed causes large fluctuations in bed control, high equipment wear and failure rate, and large heat loss of high-temperature fine powder. In addition, in traditional technology, since the cyclone is a static device, if the cyclone selection is fixed, the separation effect cannot be changed according to the adjustment of production load and changes in raw materials, which is not conducive to improving the automation of the device and production stability. Summary of the invention

[0004] The present invention aims to overcome the aggregation and return technology in the traditional fluidized bed production process of organic silicon monomers, to reduce the operating intensity of workers and realize automation; to solve the impact of large intermittent return materials on the fluidized state and the wear of equipment; to achieve controllable cyclone efficiency, to ensure that harmful impurities are completely taken out of the reaction system, and to extend the operation cycle.

[0005] The solution of the present invention is: An organic silicon monomer synthesis collection and recycling device, comprising a fluidized bed, a primary cyclone separator, a secondary cyclone separator, a secondary cyclone separator receiving hopper, a fine powder tank A, a fine powder tank B, a third cyclone separator, a third cyclone separator receiving hopper, a waste powder tank and connecting pipelines, and an automated instrument valve; The gas phase outlet at the top of the fluidized bed is connected to the inlet of the secondary cyclone separator; The gas phase outlet of the secondary cyclone separator is connected to the inlet of the tertiary cyclone separator, and the solid phase outlet of the secondary cyclone separator is connected to the receiving hopper of the second-stage cyclone separator; the receiving hopper of the second-stage cyclone separator is connected to the inlets of fine powder tank A and fine powder tank B.

[0006] A primary cyclone separator is fixed inside the fluidized bed, and the top outlet of the primary cyclone separator is connected to the gas phase outlet at the top of the fluidized bed. The primary cyclone separator is used to intercept the silicon powder and catalyst carried by the gas phase in the bed and directly return them to the middle and lower part of the fluidized bed to participate in the chemical reaction, reducing the workload of the external cyclone by 60-90%, and reducing the manual operation load and equipment investment.

[0007] A feed leg is set at the bottom of the first-stage cyclone separator, extending into the middle and lower part of the straight section of the fluidized bed, so that the fine powder recovered by the first cyclone can be discharged smoothly by gravity and participate in the reaction in the long stroke of the straight section. If the feed leg is too short, the material discharge may be blocked, and if the material is discharged to the upper part of the straight section, the recovered silicon powder and catalyst may be carried to the expansion section by the gas phase without participating in the reaction.

[0008] The first-stage cyclone separators are 2-4 in parallel, each cyclone is provided with an independent material leg, and the outlets of the cyclone separators are equidistantly collected on a main pipe, and selectively collected in the fluidized bed, or collected outside the fluidized bed.

[0009] In the embodiments of the present case, in the technical solution of the present application, several first-stage cyclone separators connected in parallel correspond to several material legs. Multiple material legs (multiple cyclone separators connected in parallel) can achieve uniformity in the step-by-step material discharge, which is convenient for process stability when the fluidized bed has a large capacity. If the capacity is small and the fluidized bed is small, fewer material legs can be set, and one will be sufficient.

[0010] The parallel outlets of the first-stage cyclone separators are collected into one pipe in the fluidized bed. The effect is that only one gas phase outlet is designed on the head of the fluidized bed, and the fluidized bed shell is simple to manufacture, but the height of the expanded section of the fluidized bed will be increased to leave space for the collecting pipe.

[0011] The effect of the first-stage cyclone separator outlet being aggregated outside the fluidized bed is that each cyclone outlet corresponds to the gas phase outlet of the fluidized bed head. The fluidized bed head will have 2-4 gas phase outlets, which are aggregated to a main pipe outside the bed. In this way, the height of the fluidized bed expansion section will be reduced, the structure outside the bed will be complicated, and it will have no effect on the process effect.

[0012] In some preferred cases, three parallel cyclone separators are arranged in the fluidized bed, and the outlets of the cyclone separators are combined outside the fluidized bed.

[0013] Fine powder tank A and fine powder tank B are connected to the solid phase inlet at the bottom of the fluidized bed through pipelines. Fine powder tank A and fine powder tank B receive and return materials alternately, and are switched by automatic valves; a nitrogen pressure pipeline is set on the top of each tank; a ceramic lined valve body (i.e. a valve body lined with ceramic and without moving parts) is set between the return pipe from the fine powder tank to the fluidized bed, the upper part of the valve body is connected to the fine powder tank pipeline, the middle part is connected to the gas booster pipeline, one end of the bottom is connected to the gas booster pipeline, and the other end is connected to the fluidized bed through a pipeline. During operation, the booster pipeline, the flow meter on the nitrogen pressure pipeline, the regulating valve, the fine powder tank pressure, and the return pipeline pressure difference cooperate to achieve quantitative and continuous return of fine powder to the bed.

[0014] The gas phase outlet of the three-stage cyclone separator is dehumidified and dust removed by the dust removal system. The solid phase outlet of the three-stage cyclone separator is connected to the receiving hopper of the three-stage cyclone separator, and the receiving hopper of the three-stage cyclone separator is connected to the waste powder tank.

[0015] The fluidized bed is provided with a heat transfer oil heat exchange pipe to maintain a constant reaction temperature. The diameter of the expanded section is 1-2 times that of the straight section, and the length is 0.3-0.8 times that of the straight section. The height of the straight section of the fluidized bed is 6-10 meters, generally 6-9 meters.

[0016] A back-blowing system is set at the bottom ash hopper of the secondary cyclone separator. The back-blowing gas uses hot nitrogen or hot methyl chloride gas. The reaction products pass through the secondary cyclone separator and then selectively go to the third-stage cyclone separator or the post-wet dust removal system.

[0017] For the above-mentioned organosilicon monomer synthesis aggregate and recycling system, the process concept is as follows: Methyl chloride, silicon powder and catalyst react in a fluidized bed at a certain pressure and temperature. The reaction products and unreacted methyl chloride, silicon powder and catalyst enter the primary cyclone separator. The unreacted silicon powder (mainly methyl chloride and silicon powder due to a small amount of catalyst) is intercepted by the primary cyclone separator and returns to the dense phase section of the fluidized bed through its feed leg to participate in the reaction again. The fine powder that is not intercepted enters the secondary cyclone separator with the gas phase for further separation. The secondary cyclone separator collects the fine powder and enters the secondary cyclone separator receiving hopper. The fine powder in the secondary cyclone separator receiving hopper is discharged alternately to fine powder tanks A and B. Fine powder tanks A and B receive and discharge materials alternately. When fine powder tank A receives materials, fine powder tank B is disconnected from the first-stage cyclone separator receiving hopper. The top of fine powder tank B is pressurized to 0.35-0.55Mpa by nitrogen. The valve of the solid phase inlet pipeline between the bottom of fine powder tank and the bottom of fluidized bed is opened. By adjusting the booster gas flow and pressure difference relationship between the front end and the side end of the special pipe fittings on the pipeline, the speed of fine powder returning to the fluidized bed in fine powder tank B can be adjusted to achieve uniform and continuous return to the bed. A small amount of ultrafine powder is entrained at the outlet of the second-stage cyclone separator and enters the third-stage cyclone separation system for gas-solid separation again. According to the reaction effect of the fluidized bed, the efficiency of the second-stage cyclone separator is adjusted by controlling the backwash gas at the bottom of the cyclone separator; the booster gas for the return of fine powder tanks A and B to the bed and the backwash gas of the second-stage cyclone include methyl chloride gas and nitrogen.

[0018] In view of the above technical concept, another object of the present invention is to provide a process for synthesizing aggregates and recycling of organic silicon monomers, comprising the following steps: (1) Methyl chloride, silicon powder and catalyst react in a fluidized bed at a certain pressure and temperature. The reaction products and unreacted methyl chloride and silicon powder enter the primary cyclone separator for interception. After being intercepted by the primary cyclone separator, they return to the dense phase section of the fluidized bed through its feed leg to participate in the reaction again. (2) The fine powder that is not intercepted enters the secondary cyclone separator with the gas phase for further separation. The fine powder collected by the secondary cyclone separator (3) enters the secondary cyclone separator receiving hopper. The fine powder in the secondary cyclone separator receiving hopper is discharged alternately to fine powder tank A and fine powder tank B. Fine powder tank A and fine powder tank B then enter the fluidized bed to participate in the reaction, thereby achieving aggregation and recycling.

[0019] A catalyst well known in the art is copper powder.

[0020] The primary cyclone separator is supported and fixed inside the fluidized bed, the top outlet of the primary cyclone separator is connected to the gas phase outlet at the top of the fluidized bed, and a material leg is arranged at the bottom of the primary cyclone separator, extending into the middle and lower part of the fluidized bed.

[0021] In some preferred embodiments, the reaction products and unreacted methyl chloride and silicon powder enter the primary cyclone separator, penetrate into the 1 / 2 of the straight section of the fluidized bed through the material legs to the lower end of the straight tube, and intercept the silicon powder and catalyst brought into the expanded diameter section of the fluidized bed. The interception efficiency in this process is 60-90%. It is further preferred that 80-90% of the unreacted silicon powder can be intercepted. The percentage is a weight percentage, and the material range of the weight percentage is any value in the range value. The silicon powder collected in the above is returned to the straight section of the fluidized bed to participate in the reaction again.

[0022] The first-stage cyclone separators are 2-4 in parallel, each cyclone is provided with an independent material leg, and the outlets of the cyclone separators are equidistantly collected on a main pipe, and selectively collected in the fluidized bed, or collected outside the fluidized bed.

[0023] Three parallel cyclone separators are arranged in the fluidized bed, and the outlets of the cyclone separators are combined outside the fluidized bed.

[0024] The multiple parallel cyclone separators can stably collect unreacted silicon powder and catalyst to avoid entering the next-stage separator. First, the continuous direct reflux fluidized bed participates in the reaction to improve the stability of the reaction. Second, the workload and equipment investment of the external cyclone are reduced, and the labor intensity of the personnel is alleviated.

[0025] In step (2), the secondary cyclone separator collects 5-45% of the total amount of silicon powder and catalyst carried out by the gas (the amount collected by the secondary cyclone / the total amount of solids entering the first, second and third stages), which enter the receiving hopper of the secondary cyclone separator. The interception efficiency of the secondary cyclone separator is 85%-95% (the amount of solids collected / the amount of solids entering the secondary cyclone).

[0026] The fine powder that is not completely collected above enters the secondary cyclone separator again for collection to realize the complete collection and return process of the material and avoid pollution.

[0027] The collected materials enter the fine powder tank A and the fine powder tank B through the receiving hopper of the stage cyclone separator, and the fine powder tank A and the fine powder tank B are alternately receiving and discharging materials.

[0028] When fine powder tank A receives material, fine powder tank B is disconnected from the receiving hopper of the secondary cyclone separator, the top of fine powder tank B is pressurized to 0.35-0.55Mpa by nitrogen, and the valve of the solid phase inlet pipeline between the bottom of fine powder tank B and the bottom of the fluidized bed is opened to achieve uniform and continuous reflux of the fluidized bed; Or, when fine powder tank B receives material, fine powder tank A is disconnected from the receiving hopper of the secondary cyclone separator, the top of fine powder tank A is pressurized to 0.35-0.55Mpa by nitrogen, and the valve of the solid phase inlet pipeline between the bottom of fine powder tank A and the bottom of the fluidized bed is opened to achieve uniform and continuous reflux of the fluidized bed.

[0029] In this way, a reciprocating cycle is realized in which when fine powder tank A receives material, fine powder tank B returns material, and then when fine powder tank B receives material, fine powder tank A returns material.

[0030] Taking a reciprocating motion as an example, the booster gas flow rate at the bottom and middle of the ceramic valve body on the pipeline from the fine powder tank B to the fluidized bed and the pressure difference between the fine powder tank and the inlet pipeline are adjusted to realize the return of the fine powder in the fine powder tank B to the fluidized bed, and the speed of the booster gas and fine powder to the fluidized bed is controlled to be 15-30m / s; Alternatively, the fine powder in fine powder tank A can be returned to the fluidized bed by adjusting the booster gas flow and pressure difference between the bottom and middle of the ceramic-lined pipe on the pipeline from fine powder tank A to the fluidized bed, and the speed of the fine powder to the fluidized bed can be controlled to be 10-20m / s; fine powder tank A and fine powder tank B are alternately fed and returned to the fluidized bed.

[0031] The booster gas is selected from methyl chloride gas and / or nitrogen; the booster gas temperature is 100-150°C. Too low a temperature will cause the organic silicon substance in the fine powder to condense and agglomerate and block the pipeline. The booster gas in the middle of the ceramic valve body is set according to the working condition during normal use, and the booster gas flow rate in the lower part of the ceramic valve body is adjusted according to the needs of powder transportation. The overall flow rate of the booster gas is 15-30m / s. The pressure difference between the fine powder tank and the bed inlet pipeline is controlled at 30-200KPa. The structural setting of the ceramic valve body can realize the flow regulation linkage of the two-way gas and the continuous stability of feeding and feeding, and the structure is wear-resistant. The flow rate of the booster gas and silicon powder enables dilute phase (dilute phase transportation refers to a small amount of material in the airflow, a low solid-gas ratio, and the material is transported in a suspended state in the airflow.) transportation, which ensures the continuity and stability of fine powder transportation and has low abrasiveness to pipeline accessories.

[0032] A small amount of ultrafine powder is carried by the outlet of the secondary cyclone separator into the third-stage cyclone separation system for further gas-solid separation, and the separated ultrafine powder is returned to the bed or discharged as needed.

[0033] The process of the present invention is implemented by using the device described above.

[0034] Advantages of the present invention: (1) Multiple units are connected in parallel at one stage. The cyclone body is set in the fluidized bed, and the cyclone outlets are merged outside the bed, which reduces the processing cost of the fluidized bed.

[0035] (2) The first-stage cyclone aggregate is directly and evenly returned to the bed, and the silicon powder collected by the second-stage cyclone is continuously and quantitatively returned to the bed, which greatly reduces the labor intensity and reduces the heat loss of fine powder outside the bed. At the same time, it effectively improves the stability of the bed layer in the fluidized bed and improves the reaction activity and selectivity.

[0036] (3) This technology reduces external wear of the device and lowers the failure rate of equipment. It requires less investment than traditional technology devices and does not require the installation of a large fine powder storage tank, thus increasing the inherent safety of the device.

[0037] (4) The secondary rotation efficiency can be adjusted according to the reaction conditions, which can better stabilize production, extend the production cycle and improve the economic benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a diagram of the organic silicon monomer synthesis collection and recycling system of the present invention, wherein: fluidized bed; 2, primary cyclone separator; 3, secondary cyclone separator; 4, secondary cyclone separator receiving hopper; 5, fine powder tank A; 6, fine powder tank B; 7, third-stage cyclone separator; 8, third-stage cyclone separator receiving hopper; 9, waste powder tank; 10, lined ceramic valve body. The remaining automatic control instruments, valves and control logic are not shown one by one, which can meet the automatic continuous collection and recycling of this system.

[0039] Figure 2 This is a diagram of the organosilicon monomer synthesis aggregation and recycling system of Example 2, wherein 1', fluidized bed; 2', first-stage cyclone separator; 3', first-stage cyclone separator receiving hopper; 4', fine powder tank A; 5', fine powder tank B; 6', second-stage cyclone separator; 7', second-stage cyclone separator receiving hopper; 8', second-stage cyclone discharge hopper; 9', third-stage cyclone separator; 10', third-stage cyclone separator receiving hopper; 11', waste powder tank.

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Each embodiment is only for illustrating the technical concept and features of the present invention, and its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0041] Example 1 A system for collecting and recycling organic silicon monomer synthesis materials, comprising a fluidized bed 1, a primary cyclone separator 2, a secondary cyclone separator 3, a secondary cyclone separator receiving hopper 4, a fine powder tank A 5, a fine powder tank B 6, a tertiary cyclone separator 7, a tertiary cyclone separator receiving hopper 8, a waste powder tank 9, and a ceramic-lined valve body 10. The gas phase outlet at the top of the fluidized bed 1 is connected to the inlet of the secondary cyclone separator 3; the gas phase outlet of the secondary cyclone separator 3 is connected to the tertiary cyclone separator 7, and the solid phase outlet is connected to the secondary cyclone separator receiving hopper 4; the secondary cyclone separator receiving hopper 4 is connected to the inlets of the fine powder tank A 5 and the fine powder tank B 6. A valve body lined with ceramic and having no moving parts is arranged between the fine powder tank and the return pipe of the fluidized bed, the upper part of the valve body is connected to the fine powder tank pipeline, the middle part is connected to the gas booster pipeline, one end of the bottom is connected to the gas booster pipeline, and one end is connected to the fluidized bed through a pipeline. During operation, the quantitative and continuous return of fine powder to the bed is achieved through the cooperation of the flow meter on the booster pipeline, the nitrogen pressure pipeline, the regulating valve, the pressure of the fine powder tank, and the pressure difference of the return pipeline.

[0042] The primary cyclone separator 2 is supported and fixed inside the fluidized bed 1, and its outlet is connected to the gas phase outlet at the top of the fluidized bed. A feed leg is arranged at the bottom of the primary cyclone separator 2, extending into the lower 1 / 5 of the fluidized bed.

[0043] The fine powder tank A5 and the fine powder tank B6 are connected to the solid phase inlet at the bottom of the fluidized bed 1 through pipelines respectively.

[0044] The outlet of the secondary cyclone separator 3 is connected to the inlet of the tertiary cyclone separator 7, the gas phase outlet of the tertiary cyclone is a dehumidification dust removal system, the solid phase outlet of the tertiary cyclone is connected to the hopper 8 of the tertiary cyclone separator, and the hopper 8 of the tertiary cyclone separator is connected to the waste powder tank 9. Each storage tank is equipped with a pressure instrument, a nitrogen pipeline is set on the top of the fine powder tank and the flow rate can be controlled, and a material level meter is designed for the fine powder tank. Fine powder tank A 5 and fine powder tank B 6 receive and return materials alternately, and are switched by automatic valves. A special pipe fitting is set on the return pipe from the fine powder tank to the fluidized bed, and a gas booster pipeline and corresponding automatic control instruments are set at the front and side ends of the special pipe fitting. The first-stage cyclone separator 2 is 3 in parallel. Each cyclone is equipped with an independent material leg, and the outlets of each cyclone are equidistantly collected on a main pipe outside the fluidized bed. A backflush system is set at the bottom ash hopper of the second-stage cyclone. After the second-stage cyclone, the reaction product can go to the third-stage cyclone system or directly to the post-wet dust removal system.

[0045] Example 2 A recycling system for synthesizing aggregates of organic silicon monomers comprises a fluidized bed 1' top connected to a primary cyclone separator 2' via a pipeline, the primary cyclone separator 2' is connected to a primary cyclone separator receiving hopper 3' via a pipeline, the primary cyclone separator receiving hopper 3' is respectively connected to a fine powder tank A 4' and a fine powder tank B 5' via pipelines, and the fine powder tank A 4' and the fine powder tank B 5' are respectively connected to a bottom inlet of the fluidized bed 1' via pipelines.

[0046] Valves are provided on the connecting pipes from the first-stage cyclone separator receiving hopper 3' to the fine powder tank A 4' and fine powder tank B 5'; valves are provided on the connecting pipes from the fine powder tank A 4' and fine powder tank B 5' to the fluidized bed 1'.

[0047] The top of the first-stage cyclone separator 2' is connected to the second-stage cyclone separator 6' via a pipeline, the bottom of the second-stage cyclone separator 6' is connected to the second-stage cyclone separator receiving hopper 7', the bottom of the second-stage cyclone separator receiving hopper 7' is connected to the second-stage cyclone discharge hopper 8', and the bottom of the second-stage cyclone separator discharge hopper 8' is connected to the bottom inlet of the fluidized bed 1' via a pipeline.

[0048] A valve is provided on the connecting pipe from the discharge hopper 8' of the secondary cyclone separator to the fluidized bed 1'.

[0049] The top of the secondary cyclone separator 6' is connected to the tertiary cyclone separator 9' through a pipeline, the bottom of the tertiary cyclone separator 9' is connected to the tertiary cyclone separator receiving hopper 10', the bottom of the tertiary cyclone separator receiving hopper 10' is connected to the waste powder tank 11', a part of the waste powder tank 11' is connected to the bottom inlet of the fluidized bed 1' through a pipeline, and a part is connected to the waste collection area.

[0050] A valve is provided on the pipeline from the waste powder tank 11 ′ to the fluidized bed 1 ′.

[0051] The process steps of the organic silicon monomer synthesis aggregate and recycling technology of the above system are as follows: silicon powder and methyl chloride react in a fluidized bed at 0.2 MPa and 300°C, and the reaction products and unreacted silicon powder and methyl chloride are recovered through a first-level cyclone outside the bed and discharged to fine powder tank A through a hopper. After A reaches a certain weight, the discharge valve is closed, and the valve for fine powder B is opened, and tank B receives the material. Tank A is pressurized to about 0.5 MPa with nitrogen, and the material is pressed into the fluidized bed once every 15-30 minutes. When pressing the material, the switch valve of the lower pipeline of the fine powder tank is opened. The amount of return to the bed is controlled by observing the weighing instrument of the fine powder tank, and the switch valve at the bottom of the fine powder tank is closed after returning to the bed. Fine powder tanks A and B are operated alternately. After the gas phase material passes through the first-stage cyclone, about 90% of the silicon powder is captured, and the remaining 10% of the silicon powder is collected in the second-stage cyclone. The collected silicon powder is pressed into the fluidized bed every 30-60 minutes, and a small amount of ultrafine powder enters the subsequent cyclone separation. The collected ultrafine powder is returned to the bed or discharged according to the situation. For a single fluidized bed reaction system with an annual output of 150,000 tons of organic silicon monomer, about 30-60 tons of silicon powder is brought out per hour. The first-stage cyclone system collects and returns about 27-54 tons of materials per hour. The venting, nitrogen, return valves and other valves are operated hundreds of times per hour, with high operating intensity and large wear and tear of valves due to frequent switching. The amount of silicon powder returned each time is more than 10 tons, which affects the stability of the fluidized bed layer. The high-temperature silicon powder also has a large heat loss during the process.

[0052] Example 3 In the organosilicon monomer synthesis aggregate and recycling system composed of Example 1, methyl chloride and silicon powder react in a fluidized bed at 0.18 MPa and 310°C, and the reaction product and unreacted methyl chloride, silicon powder and catalyst enter the first-stage cyclone separator, wherein 80-90% of the silicon powder and catalyst entering the first-stage cyclone separator are intercepted by the first-stage cyclone separator and return to the lower part of the fluidized bed through its material legs to participate in the reaction again.

[0053] The fine powder that is not intercepted enters the secondary cyclone separator with the gas phase for further separation. The secondary cyclone separator collects about 9-20% of the fine powder and enters the secondary cyclone separator receiving hopper. The fine powder in the secondary cyclone separator receiving hopper is discharged alternately to fine powder tank A and fine powder tank B. Fine powder tank A and fine powder tank B receive and discharge materials alternately. When fine powder tank A receives materials, fine powder tank B is disconnected from the secondary cyclone receiving hopper, and the top of fine powder tank B is pressurized to 0.35-0.55Mpa by nitrogen. The valve of the solid phase inlet pipeline between the bottom of fine powder tank B and the bottom of the fluidized bed is opened, and the 100°C methyl chloride booster gas flow rate at the lower and middle parts of the ceramic valve body on the pipeline is adjusted, and the pressure difference between the top pressure of fine powder tank B and the return line is controlled to be 30kpa, so that the fine powder in fine powder tank B can be evenly and continuously returned to the fluidized bed. The methyl chloride flow rate in the middle of the ceramic valve body is controlled at 200-500 standard cubic meters / hour, and the methyl chloride flow rate at the lower part of the ceramic valve body is adjusted at 300-1000 standard cubic meters / hour to control the fine powder conveying rate. The overall flow rate of the booster gas is 18m / s. After the material in the fine powder tank B enters the fluidized bed, the valve is closed, the fine powder tank A receives the material, the fine powder tank A is disconnected from the secondary cyclone separator receiving hopper, the top of the fine powder tank A is pressurized to 0.35-0.55Mpa by nitrogen, the valve of the solid phase inlet pipeline between the bottom of the fine powder tank A and the bottom of the fluidized bed is opened, and the fine powder of tank B is continuously transported back to the bed with the same process control as the fine powder tank B. After the above-mentioned reciprocating collection and recovery of fine materials, a small amount of ultrafine powder is entrained at the outlet of the secondary cyclone separator and enters the third-stage cyclone separation system for gas-solid separation again. The separated ultrafine powder is returned to the fluidized bed or discharged as needed. In a single fluidized bed reaction system with an annual output of 150,000 tons of organic silicon monomer, about 70%-80% of the silicon powder is directly returned to the bed through the first-stage cyclone, and about 15-25% of the silicon powder is recovered through the second-stage cyclone. The second cyclone return material is about 10 tons / hour. The material is uniformly and continuously returned to the bed, which has a good effect on the fluidized bed layer and reaction stability.

[0054] Example 4 In the organic silicon monomer synthesis aggregate and recycling system composed of Example 1, methyl chloride, silicon powder and catalyst react in a fluidized bed at 0.2MPa and 305°C, and the fluidized bed has a production capacity of 150,000 tons of organic silicon monomer. The bed is equipped with a first-level cyclone separator with a separation efficiency of 85-90%. The separated fine powder and catalyst are returned to the lower part of the fluidized bed through the material legs to participate in the reaction again; the reaction products, unreacted methyl chloride, unintercepted fine powder and catalyst at the gas phase outlet of the first-level cyclone separator enter the second-level cyclone separator for further separation. The second-level cyclone separator collects about 8 tons of fine powder per hour and enters the second-level cyclone separator receiving hopper. The fine powder in the second-level cyclone separator receiving hopper is alternately discharged to fine powder tank A and fine powder tank B. After fine powder tank A receives material for 1 hour, the feed valve of fine powder tank B is opened, and tank B receives material. The feed valve of fine powder tank A is closed, and tank A stops receiving material. The top of the fine powder tank A is pressurized to 0.5Mpa by nitrogen, the valve of the solid phase inlet pipeline between the bottom of the fine powder tank A and the bottom of the fluidized bed is opened, the 150℃ chloromethane booster gas in the middle of the ceramic valve body corresponding to the fine powder tank A is opened, the flow rate is 200 standard cubic meters / hour, the chloromethane booster pipeline regulating valve at the bottom of the ceramic valve is opened, the flow rate is 500 standard cubic meters / hour, and the pressure difference between the top pressure of the fine powder tank B and the return line is controlled to be 50kpa, and the fine powder tank B continuously and evenly returns 8 tons of fine powder to the bed in 1 hour, the first-level cyclone and the second-level cyclone aggregates continuously and evenly return to the bed, the fluidized bed is stable, and the fluidization effect is good. The three-stage cyclone separator collects about 100kg of fine powder per hour as waste contact discharge.

Claims

1. A system for synthesizing and recycling organic silicon monomers, characterized in that: It comprises a fluidized bed (1), a first-stage cyclone separator (2), a second-stage cyclone separator (3), a second-stage cyclone separator receiving hopper (4), a fine powder tank A (5), a fine powder tank B (6), a third-stage cyclone separator (7), a third-stage cyclone separator receiving hopper (8), a waste powder tank (9), connecting pipelines, and automated instrument valves; The gas phase outlet at the top of the fluidized bed (1) is connected to the inlet of the secondary cyclone separator (3); The solid phase outlet of the secondary cyclone separator (3) is connected to the receiving hopper (4) of the secondary cyclone separator; the receiving hopper (4) of the secondary cyclone separator is connected to the inlets of the fine powder tank A (5) and the fine powder tank B (6).

2. The organic silicon monomer synthesis aggregate and recycling device according to claim 1, characterized in that: A first-stage cyclone separator (2) is fixedly arranged inside the fluidized bed (1); a top outlet of the first-stage cyclone separator (2) is connected to a gas phase outlet at the top of the fluidized bed (1); and a feed leg is arranged at the bottom of the first-stage cyclone separator (2) and extends into the middle and lower part of the fluidized bed.

3. The organic silicon monomer synthesis aggregate and recycling device according to claim 2, characterized in that: The first-stage cyclone separators (2) are 2 to 4 connected in parallel, each cyclone is provided with an independent material leg, and the outlets of the cyclone separators are uniformly connected to a main pipe, and are selectively connected in the fluidized bed or outside the fluidized bed.

4. The organic silicon monomer synthesis aggregate and recycling device according to claim 3, characterized in that: Three parallel-connected cyclone separators are arranged in the fluidized bed (1), and the outlets of the cyclone separators are collected outside the fluidized bed (1).

5. The organic silicon monomer synthesis aggregate and recycling device according to claim 1, characterized in that: The fine powder tank A (5) and the fine powder tank B (6) are respectively connected to the solid phase inlet at the bottom of the fluidized bed (1) through pipelines; the fine powder tank A (5) and the fine powder tank B (6) are switched by automatic valves to realize alternate material receiving and material return; a nitrogen pressure pipeline is arranged at the top of each tank; a lined ceramic valve body (10) is respectively arranged between the bottom of the fine powder tank A (5) and the fine powder tank B (6) and the return pipe of the fluidized bed (1); the upper part of the lined ceramic valve body (10) is connected to the pipeline of the corresponding fine powder tank, the middle part is connected to the gas booster pipeline, one end of the bottom is connected to the gas booster pipeline, and the other end is connected to the fluidized bed through the pipeline.

6. The organic silicon monomer synthesis aggregate and recycling device according to claim 1, characterized in that: The gas phase outlet of the secondary cyclone separator (3) is connected to the inlet of the tertiary cyclone separator (7); the gas phase outlet of the tertiary cyclone separator (7) is dehumidified and dust removed by the dust removal system; the solid phase outlet of the tertiary cyclone separator (7) is connected to the receiving hopper (8) of the tertiary cyclone separator; the receiving hopper (8) of the tertiary cyclone separator is connected to the waste powder tank (9); a heat transfer oil heat exchange pipe is arranged inside the fluidized bed (1) to maintain a constant reaction temperature; the diameter of the expanded section of the fluidized bed (1) is 1 to 2 times that of the straight section, the length is 0.3 to 0.8 times that of the straight section, and the height of the straight section of the fluidized bed is 6 to 10 meters.

7. The organic silicon monomer synthesis aggregate and recycling device according to claim 1, characterized in that: A back-flushing system is provided at the bottom ash hopper of the secondary cyclone separator (3), and the reaction product passes through the secondary cyclone separator (3) and selectively goes to the third-stage cyclone separator (7) or to the post-wet dust removal system.

8. A process for synthesizing and recycling organic silicon monomers, characterized in that: The steps include: (1) Methyl chloride, silicon powder and catalyst react in a fluidized bed (1) at a certain pressure and temperature. The reaction products and unreacted methyl chloride and silicon powder enter the primary cyclone separator (2) for interception. After being intercepted by the primary cyclone separator, they return to the dense phase section of the fluidized bed through its feed leg to participate in the reaction again. (2) The fine powder that is not intercepted enters the secondary cyclone separator (3) with the gas phase for further separation. The fine powder collected by the secondary cyclone separator (3) enters the secondary cyclone separator receiving hopper (4). The fine powder in the secondary cyclone separator receiving hopper (4) is discharged alternately to fine powder tank A (5) and fine powder tank B (6). Fine powder tank A (5) and fine powder tank B (6) then enter the fluidized bed (1) respectively to participate in the reaction, thereby achieving aggregation and recycling.

9. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 8, characterized in that: The first-stage cyclone separator (2) is supported and fixed inside the fluidized bed (1); the top outlet of the first-stage cyclone separator (2) is connected to the top gas phase outlet of the fluidized bed (1); and a material leg is provided at the bottom of the first-stage cyclone separator (2) and extends into the middle and lower part of the fluidized bed.

10. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 9, characterized in that: The first-stage cyclone separators (2) are 2 to 4 connected in parallel, each cyclone separator is provided with an independent material leg, and the outlets of the cyclone separators are uniformly connected to a main pipe and selectively connected in the fluidized bed or outside the fluidized bed.

11. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 10, characterized in that: Three parallel-connected cyclone separators are arranged in the fluidized bed (1), and the outlets of the cyclone separators are collected outside the fluidized bed (1).

12. A process for synthesizing aggregates and recycling systems of organosilicon monomers according to any one of claim 11, characterized in that: In step (1), the first-stage cyclone separator (2) intercepts the silicon powder and catalyst in the gas phase with the cyclone separator, with an interception efficiency of 60%-90%, and returns to the bottom of the straight tube section of the fluidized bed to re-participate in the reaction.

13. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 8, characterized in that: In step (2), the secondary cyclone separator (3) collects 5-45% of the fine powder and enters the secondary cyclone separator receiving hopper (4); The fine powder tank A (5) and the fine powder tank B (6) receive and discharge materials alternately; When the fine powder tank A (5) receives the material, the fine powder tank B (6) is disconnected from the secondary cyclone separator receiving hopper (4), the top of the fine powder tank B (6) is pressurized to 0.35-0.55 MPa by nitrogen, and the valve of the solid phase inlet pipeline between the bottom of the fine powder tank B (6) and the bottom of the fluidized bed is opened to achieve uniform and continuous refluidization of the fluidized bed (1); Alternatively, when the fine powder tank B (6) is receiving material, the fine powder tank A (5) is disconnected from the secondary cyclone separator receiving hopper, the top of the fine powder tank A (5) is pressurized to 0.35-0.55 MPa by nitrogen, and the valve of the solid phase inlet pipeline between the bottom of the fine powder tank A (5) and the bottom of the fluidized bed is opened to achieve uniform and continuous reflux of the fluidized bed (1).

14. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 13, characterized in that: By adjusting the booster gas flow rate and pressure difference between the bottom and middle of the ceramic-lined valve body on the pipeline from the fine powder tank B (6) to the fluidized bed (1), the fine powder in the fine powder tank B (6) is returned to the fluidized bed (1), so that the speed of the fine powder and the booster gas to the fluidized bed (1) is controlled to be 10-20 m / s; Alternatively, the fine powder in the fine powder tank A (5) is returned to the fluidized bed (1) by adjusting the booster gas flow rate and pressure difference between the bottom and middle of the ceramic-lined pipe on the pipeline from the fine powder tank A (5) to the fluidized bed (1), so that the speed of the fine powder to the fluidized bed (1) is controlled to be 15-30 m / s; The fine powder tank A and the fine powder tank B receive materials and reflux the fluidized bed alternately.

15. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 14, characterized in that: The booster gas is selected from methyl chloride gas or nitrogen gas; the booster gas temperature is 100-150°C.

16. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 15, characterized in that: The booster gas in the middle of the ceramic valve body is set according to the working condition during normal use. The booster gas flow in the lower part of the ceramic valve body is adjusted according to the needs of powder transportation. The overall flow rate of the booster gas is 15-30m / s; the pressure difference between the fine powder tank and the bed inlet pipeline is controlled at 30-200KPa.

17. The process of the organic silicon monomer synthesis aggregate and recycling system according to claim 8, characterized in that: A small amount of ultrafine powder is carried by the outlet of the secondary cyclone separator (3) into the third-stage cyclone separation system for further gas-solid separation. The separated ultrafine powder is returned to the bed or discharged as required.

18. A process for a synthetic aggregate and recycling system of organic silicon monomers according to any one of claims 8 to 17, characterized in that: The process is carried out using the device described in any one of claims 1 to 7.

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