An air inlet assembly for a fluidized bed used in the synthesis of organosilicon monomers and an organosilicon fluidized bed.

Abstract

This invention provides a plateless air inlet assembly for an organosilicon fluidized bed and the organosilicon fluidized bed itself. The air inlet assembly comprises a bottom central hole air inlet and a sidewall injection air inlet. The bottom central hole air inlet is located at the bottom of the lower cone of the fluidized bed, while the sidewall injection air inlet is located on the sidewall of the cone, above the central hole. The organosilicon fluidized bed includes a lower cone, a fluidized bed body, an enlarged section, and a top end cap. Chloromethane gas enters the cone through the bottom central hole and the sidewall injection pipe, carrying silicon powder particles upwards to form a jet-fluidized flow. The silicon powder particles are carried out of the fluidized bed by the chloromethane gas from the top end cap and enter a cyclone separator. The fluidized bed is suitable for silicon powder with a wide sieve particle size distribution, which helps solve the problems of distribution plate clogging and large-volume carryover, reduces the wear of silicon powder particles on the heat exchange tubes, improves the surface renewal of silicon powder and the mixing efficiency of chloromethane gas and silicon powder particles, thereby increasing monomer yield and enabling online feeding.

Description

Technical Field

[0001] This invention relates to an air intake method combining a non-distribution plate and a side-swirling air intake in a fluidized bed for synthesizing organosilicon monomers, and to an organosilicon fluidized bed. Background Technology

[0002] The production of organosilicon materials is inseparable from methylchlorosilane monomers, among which dimethyldichlorosilane monomer (dimethyl) is the most important and largest-volume basic raw material (accounting for 80% of the total monomers). Currently, the industrial synthesis of organosilicon monomers is mainly completed in fluidized bed reactors. The performance of the fluidized bed has a significant impact on organosilicon yield, monomer selectivity, and conversion rate. Among them, the gas inlet device is the core component of the organosilicon monomer fluidized bed, playing an important role in the fluidization quality and stable operation within the fluidized bed. Large-scale organosilicon monomer fluidized beds generally use perforated gas distribution plates to fluidize materials, where the orifice size and spacing affect the pressure drop of the distributor and the fluidization quality of solid particles. The silicon powder particles used in industrial production have a wide sieve distribution, and their fluidization process is prone to particle segregation at different bed heights. A reasonable distribution plate structure design is crucial to ensuring efficient fluidization of silicon powder and reducing particle segregation. An improperly designed gas distribution plate can cause uneven gas distribution, leading to flow deviation, channeling, and leakage and blockage of the vents. This reduces the gas-solid mass transfer rate, prevents the timely removal of heat released from the reaction, and increases side reactions, thus affecting yield. To address these issues, CN216630756U discloses a combined upper and lower layer gas injection device for an organosilicon fluidized bed reactor, improving the uniformity of gas distribution within the bed and breaking up silica powder agglomerates to promote catalyst surface renewal. CN110559955A discloses a gas distributor for an organosilicon fluidized bed, with radially distributed air inlets on the distribution plate, located on the lower end face of the vent cap to prevent leakage. CN113877489A discloses a combined central and sidewall air inlet device, where most of the chloromethane gas enters through the central inlet pipe to generate jet fluidization, while a small portion enters through the sidewall inlet pipe. The aforementioned literature attempted to partially solve the problems of material leakage and uneven fluidization in the distribution plate by changing the structure of the distribution plate and the air inlet combination. However, these gas distributors did not consider the influence of particle size distribution during the design process, and could not solve the problems of particle segregation and stratification, as well as large-scale carryover. Therefore, a rationally designed air inlet device is of great significance for improving the fluidization quality in the fluidized bed, thereby increasing the monomer yield and ensuring safe production. Summary of the Invention

[0003] The purpose of this invention is to provide an air inlet assembly for an organosilicon fluidized bed and the organosilicon fluidized bed itself. This air inlet assembly and fluidized bed have a reasonable structure, which helps to solve the problem of distribution plate blockage, reduces wear of the heat exchange tubes by silicon powder particles, improves the surface renewal of silicon powder and the mixing efficiency of chloromethane gas and silicon powder particles, thereby increasing monomer yield and enabling online feeding.

[0004] The present invention provides a high-efficiency air intake combination device for organosilicon fluidized beds, wherein the air intake combination device includes a combination air intake method in which a bottom central air intake hole is provided at the bottom of the cone component and an injection device is provided on the side wall.

[0005] The central air inlet is cylindrical, with a diameter 0.08-0.15 times that of the upper part of the conical component, and is used to allow chloromethane gas to enter. The chloromethane gas enters the fluidized bed reactor vertically from the central inlet at a relatively high velocity, which reduces the accumulation of silicon powder particles on the wall surface and the blockage of silicon powder particles at the central inlet.

[0006] The injection device includes a ring section, an inlet section, and an injection pipe. The ring section surrounds the outside of the cone-shaped component and provides a pressure environment to ensure that the raw material chloromethane gas is ejected from the nozzle at a high gas velocity to form a swirling flow. The injection pipe extends into the interior of the cone-shaped component. The inlet section is fixed to the side wall of the cone between the ring section and the injection pipe, and its diameter gradually decreases.

[0007] Several injection pipes are installed in the inlet section, with a length between 50-300 mm and a diameter between 5-20 mm.

[0008] The injection pipe is installed in the inlet section at a 30-50° offset from the radial direction on the same cross section of the cone and is inclined upwards. This is used to make the chloromethane gas rise and flow in a rotating state in the fluidized bed. The side wall injection can increase the radial mixing of silicon powder particles and the renewal of the silicon powder particle surface, which is conducive to a more uniform distribution of silicon powder particles in the radial and axial directions.

[0009] The cone-shaped component is equipped with symmetrically arranged silicon powder feeding ports and contact body return ports; and the silicon powder feeding ports and contact body return ports are located between the central air inlet and the spraying device to realize the entry and return of silicon powder.

[0010] Another object of the present invention is to provide an organosilicon fluidized bed, including the aforementioned air intake assembly.

[0011] The upper part of the cone component is connected to the fluidized bed body via a flange and fixed with bolts; the upper part of the fluidized bed body is provided with an enlarged section, the diameter of which is 1.2-1.5 times the diameter of the fluidized bed body.

[0012] The upper part of the expansion section is equipped with an upper end cap, and the upper part of the upper end cap is equipped with a material outlet. The fresh silicon powder is added into the fluidized bed reactor through the feed port, while the silicon powder recovered from the cyclone separator is returned to the bed through the return port.

[0013] A method for preparing a dimethyldichlorosilane monomer, comprising reacting it in an organosilicon fluidized bed, and the preparation steps are as follows:

[0014] Fresh silicon powder enters the cone component through the silicon powder feed port and mixes with chloromethane gas from the bottom center air inlet. At the same time, chloromethane gas enters the cone component through the injection device. Under the reaction temperature and pressure conditions, the chloromethane gas carries the silicon powder upward within the cone component, forming a jet fluidization that enters the fluidized bed. This causes the chloromethane gas to react in an upward and rotating state within the fluidized bed, thus preparing dimethyldichlorosilane monomer.

[0015] The flow rate ratio of chloromethane gas entering through the bottom center inlet to that entering through the self-injection device is 0.3-0.6; the velocity of chloromethane gas entering the conical component through the bottom center inlet is 3-10 m / s; the velocity of chloromethane gas entering the conical component through the self-injection device is 150-300 m / s. This gas intake combination ensures good axial and radial dispersion of silicon powder particles in the fluidized bed, which helps reduce silicon powder particle accumulation in the wall area, reduces wear of the heat exchange tubes by silicon powder particles, solves the problem of gas distribution plate blockage, and enables online feeding.

[0016] In some embodiments, a fresh silicon powder feed port and a silicon powder return port are respectively installed on the side wall of the cone, above the central hole. Fresh silicon powder is added into the fluidized bed reactor through the feed port. Unreacted silicon powder particles are carried out of the fluidized bed from the top end cap by chloromethane gas and enter the cyclone separator. Silicon powder recovered from the cyclone separator is returned to the bed through the return port.

[0017] Beneficial effects

[0018] The purpose of this invention is to provide a high-efficiency air intake combination device for organosilicon fluidized beds. The air intake device has a reasonable structure, which helps to reduce the accumulation of silicon powder particles in the wall area, ensures that the silicon powder particles are evenly distributed in the axial and radial directions, reduces particle segregation, and improves the mixing efficiency of chloromethane gas and silicon powder particles, thereby improving the monomer yield.

[0019] The key points and protection points of this invention.

[0020] A high-efficiency air intake combination device and the main structure of an organosilicon fluidized bed. Using the organosilicon fluidized bed described in this invention can reduce silicon powder particle accumulation in the wall area, ensure uniform axial and radial distribution of silicon powder particles, increase particle circulation speed, and improve monomer yield. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the organosilicon fluidized bed structure of the present invention.

[0022] Figure 2 This is a top view of the structural schematic diagram of the injection device.

[0023] Figure 3 Simplify the front view of the tapered component.

[0024] In the above-mentioned device, there are: bottom center air inlet 1, fresh silicon powder feed port 2, contact body return port 3, side wall jet air inlet 4, lower cone 5, fluidized bed body 6, expansion section 7, upper end cap 8, material outlet 9, ring pipe section 10, inlet section 11, and jet pipe 12. Detailed Implementation

[0025] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0026] Example 1

[0027] See Figure 1 A high-efficiency air intake combination device for organosilicon fluidized beds, the air intake combination device includes a combination air intake method in which a bottom center air intake hole 1 is provided at the bottom of the cone component and an injection device 4 is provided on the side wall.

[0028] The central air inlet 1 is cylindrical, and its diameter is 0.12 times the diameter of the upper part of the conical component, which is used to allow the entry of chloromethane gas.

[0029] The injection device 4 includes a ring section 10, an inlet section 11, and an injection pipe 12; the ring section 10 surrounds the outside of the cone component to allow the entry of chloromethane gas and provide a suitable pressure environment; the injection pipe 12 extends into the interior of the cone component; the injection pipe 12 is fixed to the side wall of the cone between the ring section 10 and the inlet section 11, and its diameter gradually decreases.

[0030] Several injection pipes 12 are installed inside the inlet section 11. Each injection pipe 12 is 240 mm long and 16 mm in diameter. The injection pipes are made of pressure-resistant carbon steel.

[0031] The injection pipe 12 is installed in the inlet section 11 at a 45° offset from the radial direction on the same cross section of the cone, so as to enable the chloromethane gas to be fed in a rotating state and rise into the fluidized bed.

[0032] The cone-shaped component is also symmetrically provided with a silicon powder feeding port 2 and a contact body return port 3; and the silicon powder feeding port 2 and the contact body return port 3 are located between the central air inlet 1 and the spraying device 4, for the purpose of realizing the entry and return of silicon powder.

[0033] Example 2

[0034] An organosilicon fluidized bed is disclosed, wherein the air inlet assembly adopts the structure of Example 1. The upper part of the cone-shaped component in the air inlet assembly is connected to the fluidized bed body 6 via a flange and secured with bolts. An enlarged section 7 is provided on the upper part of the fluidized bed body 6, the diameter of which is 1.2 times the diameter of the fluidized bed body 6. An upper end cap is provided on the upper part of the enlarged section, and a material outlet is provided on the upper part of the upper end cap.

[0035] Example 3

[0036] A method for preparing a dimethyldichlorosilane monomer, comprising reacting in an organosilicon fluidized bed as described in Example 2, and the preparation steps are as follows:

[0037] Fresh silicon powder enters the cone-shaped reactor through the silicon powder feed port 2 and mixes with chloromethane gas from the bottom center inlet 1. Simultaneously, chloromethane gas enters the cone-shaped reactor through the injection device 4. Under the reaction temperature and pressure conditions (reaction temperature between 285-325℃, pressure between 0.15-0.35MPa), the chloromethane gas carries the silicon powder upwards within the cone-shaped reactor, forming a jet-fluidized flow into the fluidized bed. This causes the chloromethane gas to react in an upward and rotating state within the fluidized bed, producing dimethyldichlorosilane monomer. Fresh silicon powder is replenished into the fluidized bed reactor through the feed port. Unreacted silicon powder particles are carried out of the fluidized bed by the chloromethane gas from the top end cap and enter the cyclone separator. Silicon powder recovered from the cyclone separator is returned to the bed through the return port.

[0038] The flow rate ratio of the chloromethane gas entering through the bottom central inlet 1 to that entering through the self-injection device 4 is 0.5; the velocity of the chloromethane gas entering the conical component through the bottom central inlet 1 is 10 m / s; and the velocity of the chloromethane gas entering the conical component through the self-injection device 4 is 300 m / s. Using the technical solution of this invention, there are no blockage problems during the first three months of operation, the accumulation of silicon powder on the wall surface is small, and it does not affect the stable production of materials. The combined jetting and sidewall jetting air intake method increases the axial and radial mixing of silicon powder particles, improves the silicon powder particle circulation, and thus improves the reaction efficiency, enabling a single-pass conversion rate of chloromethane to reach 55% and a monomer space-time yield of 280 kg / t silicon powder•h.

Claims

1. A high-efficiency air intake assembly for an organosilicon fluidized bed, characterized in that, The air intake assembly includes a combination of a bottom center air intake hole (1) at the bottom of the vertebral body component and an injection device (4) on the side wall. The injection device (4) includes a ring pipe section (10), an inlet section (11), and an injection pipe (12). The injection pipe (12) extends into the interior of the vertebral body component. The inlet section (11) is fixed to the side wall of the vertebral body between the ring pipe section (10) and the injection pipe (12), and its diameter gradually decreases. Several injection pipes (12) are installed in the inlet section (11). 12) The length is between 50-300mm and the diameter is between 5-20mm. The spray pipe is installed at the end of the inlet section (11) on the same cross section of the cone at a deviation of 30-50° from the radial direction, so as to realize the upward flow of chloromethane gas in the fluidized bed in a rotating state; the cone component is also symmetrically provided with silicon powder feed port (2) and contact body return port (3); the silicon powder feed port (2) and contact body return port (3) are located between the central air inlet (1) and the spray device (4) to realize the entry of silicon powder and the entry of contact body return material.

2. The high-efficiency air intake assembly for organosilicon fluidized beds according to claim 1, characterized in that, The central air inlet (1) is cylindrical, and its diameter is 0.08-0.15 times the diameter of the upper part of the cone component, which is used to allow the entry of chloromethane gas.

3. The high-efficiency air intake assembly for organosilicon fluidized beds according to claim 1, characterized in that... The annular section (10) surrounds the outside of the cone-shaped component to allow the entry of chloromethane gas and provide a suitable pressure environment.

4. An organosilicon fluidized bed, characterized in that, Includes the air intake assembly as described in any one of claims 1-3.

5. The organosilicon fluidized bed according to claim 4, characterized in that, The upper part of the cone component is connected to the fluidized bed body (6) by a flange and fixed with bolts; the upper part of the fluidized bed body (6) is provided with an enlarged section (7), the diameter of which is 1.2-1.5 times the diameter of the fluidized bed body (6).

6. A method for preparing a dimethyldichlorosilane monomer, characterized in that, The preparation is carried out by reaction using the organosilicon fluidized bed described in claim 4 or 5, and the preparation steps are as follows: Fresh silicon powder enters the cone component through the silicon powder feed port and mixes with chloromethane gas from the bottom center air inlet. At the same time, chloromethane gas enters the cone component through the injection device. Under the reaction temperature and pressure conditions, the chloromethane gas carries the silicon powder upward within the cone component. The injection air intake method creates a radially mixed and enhanced swirling state of the chloromethane gas in the fluidized bed, which is conducive to the reaction and prepares dimethyldichlorosilane monomer.

7. The method for preparing dimethyldichlorosilane monomer according to claim 6, characterized in that, The flow rate ratio of chloromethane gas entering through the bottom center inlet to that entering through the self-injection device is 0.3-0.

6.

8. The method for preparing dimethyldichlorosilane monomer according to claim 7, characterized in that, The velocity of chloromethane gas entering the cone-shaped component from the bottom center air inlet is 3-10 m / s.

9. The method for preparing dimethyldichlorosilane monomer according to claim 8, characterized in that, The velocity of chloromethane gas entering the cone-shaped component from the injection device is 150-300 m / s.

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