An ultra large fluidized bed reaction system

Abstract

The ultra-large fluidized bed reactor system provided by this invention includes a tank, a distributor, and a heat exchange tube bundle. The heat exchange tube bundle is connected to the inner wall of the tank via hangers at both ends. An annular jet pipe, coaxial with the tank, is installed between the distributor and the heat exchange tube bundle. A ring of nozzles is provided at the top of the jet pipe, and a gas supply pipe is connected to the bottom of the jet pipe. The gas supply pipe passes downwards through the distributor and the tank and connects to the high-pressure reaction gas. In use, this ultra-large fluidized bed reactor system can significantly reduce obstruction of the mixed fluid. While improving fluidization permeability, the high-speed annular jet sprayed through the heat exchange tube bundle guides and accelerates the mixed fluid in the tank, thereby forming a stable fluidized bed state, increasing the yield of the target product, and reducing catalyst pulverization and loss caused by turbulence. This enables the ultra-large fluidized bed reactor system to achieve a production capacity of 400,000 tons per year with low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of fluidized bed reactor technology, and more specifically to an ultra-large fluidized bed reaction system. Background Technology

[0002] Fluidized bed reactors are core equipment for the production of organosilicon, trichlorosilane, and polycrystalline silicon monomers, as well as core equipment in coal chemical gasification and synthesis plants. The large-scale development of fluidized bed reactors is key to energy conservation and consumption reduction.

[0003] like Figure 1 As shown, the structure of a traditional fluidized bed reactor includes a tank, a flat distributor located inside the tank, and a heat exchange tube bundle. The distributor is located at the bottom of the tank, and the heat exchange tube bundle extends axially along the tank. The reactant gas enters from below the distributor, disperses upwards, and mixes with the material particles. The mixed fluid flows upwards through the heat exchange tube bundle, releasing or absorbing heat to produce a reaction. The reactants flow out from the top outlet of the tank for separation. Because the heat exchange tube bundle has multiple layers of supporting grids, the fluidization effect is greatly obstructed, resulting in insufficient fluidization permeability. When scaled up, at least the following problems exist: 1. It is difficult to establish a stable fluidized bed state; 2. The residence time of the gas and solid phases is long, leading to inappropriate product distribution and low yield of the target product; 3. The material particles and reactant gas are violently agitated in turbulent flow, which accelerates the pulverization of the catalyst, causing it to be carried out and lost; 4. The outer layer of the material particles is easily coated, resulting in low reaction efficiency; 5. Pure tube heat exchange makes it difficult to further improve the heat exchange efficiency. Summary of the Invention

[0004] The purpose of this invention is to overcome one or more drawbacks in the prior art and provide an ultra-large fluidized bed reaction system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is an ultra-large fluidized bed reaction system, including a tank, a distributor, and a heat exchange tube bundle; the two ends of the heat exchange tube bundle are respectively connected to the inner wall of the tank through hangers; an annular jet pipe is provided between the distributor and the heat exchange tube bundle; the jet pipe is coaxial with the tank; a ring of spray holes is provided at the top of the jet pipe; a gas supply pipe is connected to the bottom of the jet pipe; the gas supply pipe passes downward through the distributor and the tank and is connected to the high-pressure reaction gas; in use, the jet pipe sprays a high-speed annular jet that penetrates the heat exchange tube bundle to guide and accelerate the mixed fluid in the tank.

[0006] Preferably, the spray pipe includes an inner pipe, an outer pipe located outside the inner pipe, and a short pipe connecting the inner pipe and the outer pipe. The inner pipe and the outer pipe are provided with spray holes. There are two short pipes symmetrically distributed along the axis of the tank.

[0007] Preferably, the heat exchange tube bundle includes multiple heat exchange straight tubes and a U-shaped tube connecting the top and bottom of these heat exchange straight tubes. The upper part of the heat exchange straight tube corresponds to the dilute phase region, and star-shaped fins are connected to the outer wall of this part.

[0008] More preferably, the heat exchange tube bundle has a cross-section that is a regular hexagonal coaxial with the tank body. On this cross-section, the distribution density of the heat exchange straight tubes corresponding to the jet pipe region is 40%-60% lower than that in other regions.

[0009] Preferably, the distributor is a conical distributor coaxial with the tank body, and a discharge pipe is connected to the center of the bottom of the distributor. The discharge pipe is located on one side of the air supply pipe and extends downward through the tank body to form a discharge port.

[0010] Preferably, the lower part of the tank is connected to a feed injector, which includes an inclined jet pipe that is lower than the feed pipe and higher than the distributor. There are two inclined jet pipes that are symmetrically distributed on both sides of the feed pipe of the tank. The shortest distance from the intersection of the extended lines of the centerlines of the two inclined jet pipes to the inner wall of the tank is 25%-35% of the radius of the tank.

[0011] More preferably, there are multiple feed injectors evenly distributed around the centerline of the tank body, the oblique jet pipes of all the feed injectors are connected to the reaction gas pipe, all the feed pipes are connected to the material particle pipe, and the material particle pipe and the reaction gas pipe are each provided with a temperature regulator that is connected to the jacket of the tank body.

[0012] More preferably, the reaction gas pipe is bypassed by a first branch pipe connected to the air inlet at the bottom of the tank and a second branch pipe connected to the material particle pipe, and both the first branch pipe and the second branch pipe are located between the temperature controller and the tank.

[0013] Preferably, a primary separator and a secondary separator are sequentially connected to the top outlet of the tank, and a return bed pipe extending downward to the lower end of the heat exchange tube bundle is also provided on the top of the tank. The upper opening of the return bed pipe is connected to the return port of the primary separator and the secondary separator.

[0014] Preferably, a steam heater is provided on one side of the tank body. The steam heater is connected to the heat exchange tube bundle to heat the heat transfer oil in the heat exchange tube bundle. The heat transfer oil flowing out of the heat exchange tube bundle first enters the jacket of the tank body, undergoes secondary heat release, and then flows back to the steam heater.

[0015] Due to the application of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art: 1. The heat exchange tube bundle is connected to the tank only through hangers at both ends, eliminating the need for multi-layer support grids, significantly reducing obstruction of the mixed fluid, and improving the permeability of fluidization.

[0016] 2. By adding an annular jet pipe between the distributor and the heat exchange tube bundle and introducing high-pressure reaction gas, a high-speed annular jet that penetrates the heat exchange tube bundle can be formed to guide and accelerate the mixed fluid in the tank, thereby forming a stable fluidized bed state, improving the yield of the target product, and reducing catalyst pulverization and loss caused by turbulence.

[0017] 3. It can realize the scaling up of fluidized bed reactors, achieving a production capacity of 400,000 tons (and above) per year with low energy consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a traditional fluidized bed reactor.

[0019] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0020] Figure 3 yes Figure 2 A partially enlarged schematic diagram of the feed injector.

[0021] Figure 4 yes Figure 2 A schematic diagram of the cross-section of the feed injector.

[0022] Figure 5 yes Figure 2 A magnified view of a portion of the central jet pipe.

[0023] Figure 6 yes Figure 2 A schematic diagram of the cross-section of the central jet pipe.

[0024] Figure 7 yes Figure 2 A schematic diagram of the lower cross-section of the heat exchanger tube bundle.

[0025] Figure 8 yes Figure 2 A schematic diagram showing the connection between the straight heat exchange tubes and the U-shaped tubes in the heat exchange tube bundle.

[0026] Figure 9 yes Figure 8 A schematic diagram of the cross-section of the straight heat exchanger tube.

[0027] Figure 10 This is a schematic cross-sectional view of the lower part of the heat exchange tube bundle in Embodiment 2 of the present invention.

[0028] The components are as follows: 1. High-pressure chloromethane gas; 2. Chloromethane gas pipe; 3. Material particle pipe; 4. Temperature controller; 5. First branch pipe; 6. Second branch pipe; 7. Support grid; 8. Steam heater; 10. Tank body; 11. Bottom air inlet; 12. Feed pipe; 13. Top outlet; 14. Feed injector; 15. Angled jet pipe; 16. Arc pipe; 17. Jacket; 181. Primary separator; 182. Secondary separator; 19. Return bed pipe; 20. Distributor; 21. Discharge pipe; 22. Discharge port; 30. Heat exchange tube bundle; 31. Upper hanger; 32. Lower hanger; 33. Heat exchange straight pipe; 34. U-shaped pipe; 35. Star-shaped fins; 36. Zone; 40. Spray pipe; 41. Spray hole; 42. Gas supply pipe; 43. Inner pipe; 44. Outer pipe; 45. Short pipe. Detailed Implementation

[0029] Example 1, as Figures 2 to 9 As shown, this invention provides an ultra-large fluidized bed reaction system for the organosilicon industry. It includes a tank 10, a distributor 20, and a heat exchange tube bundle 30. The tank 10 extends vertically, the distributor 20 is located inside the tank 10 and at its bottom, and the heat exchange tube bundle 30 is located inside the tank 10 and extends axially. Specifically, the tank 10 has two bottom inlets 11 for introducing chloromethane gas, located below the distributor 20. These two bottom inlets 11 are symmetrically distributed along the axis of the tank 10. The tank 10 also has two feed pipes 12 for supplying silicon powder (containing copper catalyst powder). These feed pipes 12 are higher than the distributor 20 and lower than the heat exchange tube bundle 30. These two feed pipes 12 are also symmetrically distributed along the axis of the tank 10. The heat exchange tube bundle 30 is symmetrically distributed, with a top outlet 13 at the center of the top of the tank 10. In this embodiment, the two ends of the heat exchange tube bundle 30 are connected to the inner wall of the tank 10 through an upper hanger 31 and a lower hanger 32, respectively. An annular jet pipe 40 is provided between the distributor 20 and the heat exchange tube bundle 30. The jet pipe 40 is coaxial with the tank 10 and parallel to the horizontal plane. A ring of spray holes 41 is provided at the top of the jet pipe 40. A gas supply pipe 42 is connected to the bottom of the jet pipe 40. The gas supply pipe 42 passes downward through the distributor 20 and the tank 10 and is connected to the high-pressure chloromethane gas 1. In use, the jet pipe 40 sprays a high-speed annular jet that penetrates the heat exchange tube bundle 30 to guide and accelerate the mixed fluid formed by the chloromethane gas sent into the tank 10 through the bottom air inlet 11 and the silicon powder sent into the feed pipe 12.

[0030] The advantage of this setup is that it can significantly reduce the obstruction of the mixed fluid, improve fluidization permeability, and use a high-speed annular jet to guide and accelerate the mixed fluid, thereby forming a stable fluidized bed state, improving the yield of the target product, and reducing catalyst pulverization and loss caused by turbulence. This enables the ultra-large fluidized bed reaction system to achieve a production capacity of 400,000 tons per year with low energy consumption.

[0031] To ensure the above effects, in this embodiment, the jet pipe 40 includes an inner pipe 43, an outer pipe 44 located outside the inner pipe 43, and a short pipe 45 connecting the inner pipe 43 and the outer pipe 44. Both the inner pipe 43 and the outer pipe 44 are provided with nozzles 41. There are two short pipes 45, which are symmetrically distributed along the axis of the tank 10, so that the inner pipe 43 and the outer pipe 44 remain coaxial. Furthermore, the high-speed annular jet ejected by the jet pipe 40 should be as close as possible to the middle position in the radial direction of the heat exchange tube bundle 30. That is, the radius of the outer pipe 44 should not exceed 65% of the radius of the tank 10. In this embodiment, the radius of the outer pipe 44 is 60% of the radius of the tank 10.

[0032] In this embodiment, the distributor 20 is a conical distributor coaxial with the tank body 10. The bottom center of the distributor 20 is connected to the discharge pipe 21, which is located on one side of the air supply pipe 42. The discharge pipe 21 penetrates the tank body 10 downward to form a discharge port 22. The distributor 20 can better cooperate with the spray pipe 40 to form a stable fluidized bed.

[0033] In this embodiment, the cross-section of the heat exchange tube bundle 30 is a regular hexagon coaxial with the tank body 10 (in other embodiments, the cross-section of the heat exchange tube bundle 30 may also be a circle, equilateral triangle, rectangle, or other regular polygon). The heat exchange tube bundle 30 includes multiple heat exchange straight tubes 33 and U-shaped tubes 34 connecting the top and bottom of these heat exchange straight tubes 33. Due to the increased flow velocity of the mixed fluid, the interface between the dilute phase region and the dense phase region shifts upward. The upper part of the heat exchange straight tube 33 corresponds to the dilute phase region, and the outer wall of this part is connected with star-shaped fins 35. The star-shaped fins 35 consist of six fins extending along the axis of the heat exchange straight tube 33 towards... The heat exchange tubes 33 are arranged in a radiating, plate-like configuration. This configuration improves the heat exchange efficiency of the heat exchange tubes 33 in the dilute phase region. At the same time, the lower part of the heat exchange tubes 33 in the dense phase region remains a bare tube, which does not obstruct the flow of the mixed fluid in the dense phase region and does not affect the fluidized bed state. Under the same conditions, the heat exchange efficiency of the heat exchange tubes 33 is 4%-6% higher than that of the pure bare tubes. The fluidized bed state formed by the heat exchange tube bundle 30 can make the temperature distribution of the ultra-large fluidized bed reaction system more uniform. The temperature difference from bottom to top is basically controlled within ±3 degrees, thereby improving the reaction efficiency by 3%-5%.

[0034] Under the influence of temperature and copper powder catalyst, silicon powder continuously emulsifies with chloromethane in the flow field. During the reaction, some carbon deposits gradually accumulate on the outside of the silicon powder, affecting subsequent reactions. To solve this problem, in this embodiment, the lower part of the tank 10 is connected to a feed injector 14, which includes an inclined jet pipe 15 that is lower than the feed pipe 12 and higher than the distributor 20 and the jet pipe 40. There are two inclined jet pipes 15, which are symmetrically distributed on both sides of the feed pipe 12. The shortest distance from the intersection of the extended lines of the centerlines of these two inclined jet pipes 15 to the inner wall of the tank 10 is preferably 25%-35% of the radius of the tank 10. In this embodiment, this proportion is 30% to achieve self-cleaning of silicon powder and avoid premature feeding of silicon powder into the high-speed annular jet.

[0035] In this embodiment, there are four feed injectors 14, evenly distributed around the axis of the tank body 10. Two of them correspond to two feed pipes 12, and the other two serve as the basis for further improvements. The two oblique jet pipes 15 of each feed injector 14 are connected to the two ends of the same arc-shaped pipe 16. The arc-shaped pipe 16 is located on the outside of the tank body 10 and is coaxial with the tank body 10. The arc-shaped pipes 16 of all feed injectors 14 are connected to the reaction gas pipe 2 (chloromethane pipe), and all feed pipes 12 are connected to the material particle pipe 3 (silicon powder pipe). The material particle pipe 3 and the reaction gas pipe 2 are both equipped with a temperature controller 4 that is connected to the jacket 17 of the tank body 10 to achieve preheating. In order to facilitate the feeding of silicon powder and optimize the chloromethane gas supply pipeline, the reaction gas pipe 2 is further connected to a first branch pipe 5 that is connected to the bottom air inlet 11 of the tank body 10 and a second branch pipe 6 that is connected to the material particle pipe 3. The first branch pipe 5 and the second branch pipe 6 are both located between the temperature controller 4 and the tank body 10.

[0036] This setup enables self-cleaning of carbon deposits on the surface of silicon powder, with a cleaning efficiency of up to 90%. Combined with the reduction in catalyst pulverization and loss, it can improve the overall reaction efficiency of this ultra-large fluidized bed reaction system by 10%-12%, and reduce silicon powder consumption by about 20% and catalyst consumption by about 15% when producing a unit of product.

[0037] To achieve better product screening results and avoid waste, in this embodiment, the top outlet 13 of the tank 10 is connected in sequence to a primary separator 181 and a secondary separator 182. The top of the tank 10 is also provided with a return bed pipe 19 that extends downward to the lower end of the heat exchange tube bundle 30 and is close to the lower hanger 32. The upper opening of the return bed pipe 19 is connected to the return port of the primary separator 181 and the secondary separator 182.

[0038] To achieve stable heating, in this embodiment, a steam heater 8 is provided on one side of the tank 10. The steam heater 8 is connected to the heat exchange tube bundle 30 to heat the heat transfer oil in the heat exchange tube bundle 30. The heat transfer oil flowing out of the heat exchange tube bundle 30 first enters the jacket 17 of the tank 10, and after secondary heat release, it flows back to the steam heater 8. The heat transfer oil in the heat exchange tube bundle 30 dissipates heat from the outside to the inside along the radial direction of the tank 10, forming an interdigital effect with the high-speed annular jet that gradually diffuses upward and outward, thus achieving sufficient heat exchange.

[0039] Example 2, as Figure 10 As shown, Embodiment 2 is basically the same as Embodiment 1, except that, in order to further improve fluidization permeability, the distribution density of the heat exchange straight tubes 33 corresponding to the jet pipe 40 region 36 on the cross-section of the heat exchange tube bundle 30 is 40%-60% lower than that in other regions. Specifically, in this embodiment, the ratio is 50%.

[0040] It should be noted that, in the above embodiment, the pressure of the high-pressure chloromethane gas 1 is the same as the gas pressure in the chloromethane gas pipe 2. Two times or more .

[0041] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A large-scale fluidized bed reaction system, comprising a tank, a distributor, and a heat exchange tube bundle; characterized in that: Both ends of the heat exchange tube bundle are connected to the inner wall of the tank via hangers. An annular jet pipe is provided between the distributor and the heat exchange tube bundle. The jet pipe is coaxial with the tank and has a ring of nozzles at the top. A gas supply pipe is connected to the bottom of the jet pipe. The gas supply pipe passes downward through the distributor and the tank and is connected to the high-pressure reaction gas. In use, the jet pipe sprays a high-speed annular jet that penetrates the heat exchange tube bundle to guide and accelerate the mixed fluid in the tank.

2. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: The jet pipe includes an inner pipe, an outer pipe located outside the inner pipe, and a short pipe connecting the inner pipe and the outer pipe. Both the inner pipe and the outer pipe are provided with the jet holes. There are two short pipes symmetrically distributed along the axis of the tank.

3. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: The heat exchange tube bundle includes multiple heat exchange straight tubes and a U-shaped tube connecting the top and bottom of these heat exchange straight tubes. The upper part of the heat exchange straight tubes corresponds to the dilute phase region, and star-shaped fins are connected to the outer wall of this part.

4. The ultra-large fluidized bed reaction system according to claim 3, characterized in that: The heat exchange tube bundle has a cross-section that is a regular hexagonal shape coaxial with the tank body. On this cross-section, the distribution density of the heat exchange straight tubes corresponding to the jet pipe region is 40%-60% lower than that in other regions.

5. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: The distributor is a conical distributor coaxial with the tank body. The bottom center of the distributor is connected to a discharge pipe, which is located on one side of the air supply pipe and extends downward through the tank body to form a discharge port.

6. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: The lower part of the tank is connected to a feed injector, which includes an inclined jet pipe that is lower than the feed pipe and higher than the distributor. There are two inclined jet pipes that are symmetrically distributed on both sides of the feed pipe of the tank. The shortest distance from the intersection of the extended lines of the center lines of the two inclined jet pipes to the inner wall of the tank is 25%-35% of the radius of the tank.

7. The ultra-large fluidized bed reaction system according to claim 6, characterized in that: The feed injectors are multiple and evenly distributed around the centerline of the tank body. The oblique jet pipes of all the feed injectors are connected to the reaction gas pipe, and all the feed pipes are connected to the material particle pipe. The material particle pipe and the reaction gas pipe are each equipped with a temperature controller that is connected to the jacket of the tank body.

8. The ultra-large fluidized bed reaction system according to claim 7, characterized in that: The reaction gas pipe is bypassed by a first branch pipe that connects to the air inlet at the bottom of the tank and a second branch pipe that connects to the material particle pipe. Both the first branch pipe and the second branch pipe are located between the temperature controller and the tank.

9. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: The top outlet of the tank is connected in sequence to a primary separator and a secondary separator. The top of the tank is also provided with a return bed pipe that extends downward to the lower end of the heat exchange tube bundle. The upper opening of the return bed pipe is connected to the return port of the primary separator and the secondary separator.

10. The ultra-large fluidized bed reaction system according to claim 1, characterized in that: A steam heater is provided on one side of the tank body. The steam heater is connected to the heat exchange tube bundle to heat the heat transfer oil in the heat exchange tube bundle. The heat transfer oil flowing out of the heat exchange tube bundle first enters the jacket of the tank body, undergoes secondary heat release, and then flows back to the steam heater.

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