Novel hydrochlorination coupling fluidized bed reactor

Abstract

The utility model discloses a novel hydrochlorination coupling fluidized bed reactor which comprises a fluidized bed reactor, a cyclone separator and a hydrogen chloride gas distributor, one group of cyclone separators are arranged at the upper part in the fluidized bed reactor; and the hydrogen chloride gas distributor is arranged at the middle part in the fluidized bed reactor. Fine powder generated in the cold hydrogenation fluidized bed is consumed and utilized in the dilute phase section of the fluidized bed. HCl gas is introduced into the upper part of the reaction area of the cold hydrogenation fluidized bed to react with fine-particle silicon powder which does not participate in the cold hydrogenation main reaction in the dilute phase section, and the silicon powder contained in the fine powder is consumed, so that the stability of the fluidized bed is effectively improved, and the product yield is improved.

Description

Technical Field

[0001] The utility model belongs to the field of polysilicon production, and particularly relates to a novel hydrochlorination coupled fluidized bed reactor. Background Art

[0002] In the hydrogenation process of polysilicon production, the fluidized bed reactor is the core equipment of this process. The process is that the mixed gas of silicon tetrachloride and hydrogen is heated to a certain temperature and then enters the fluidized bed, where the industrial silicon powder mixed with a certain proportion of catalyst is fluidized to carry out the reaction to generate trichlorosilane. As the reaction progresses, the particle size of the silicon powder gradually decreases; the industrial silicon powder contains other impurities that do not participate in the hydrogenation reaction, and the fine particles of silicon powder and impurities entrained by the reaction gas are discharged from the top of the fluidized bed. In order to improve the utilization rate of the silicon powder, the existing process sets a cyclone separator inside the fluidized bed to separate the larger particles of silicon powder and re-add them to the reaction zone of the fluidized bed; or cyclone separators are set both inside the fluidized bed and in the outlet pipeline to separate the silicon powder in the gas.

[0003] The existing process improves the utilization rate of the silicon powder to a certain extent and reduces the cost, but there is still a considerable part of the silicon powder that is not utilized. And as the operation time of the device increases, a large amount of fine silicon powder and impurities will still accumulate in the bed. These fine particles have high viscosity and are easy to agglomerate, resulting in abnormal fluidization forms in the fluidized bed, such as slugging and channeling. The deterioration of the fluidization form further affects the system stability and reduces the yield. Moreover, the increase in impurities will gradually reduce the proportion of silicon powder in the solid phase in the fluidized bed, reduce the effective bed layer, greatly reduce the raw material gas-solid contact area, reduce the yield, and greatly shorten the operation cycle of the device. Especially for the fluidized bed operating at a high bed layer, the discharge of more silicon powder from the fluidized bed will cause the three-stage heat exchanger used for heat exchange of the gas before and after the reaction to be blocked, reduce the heat exchange efficiency, increase the power consumption of the system, and serious blockage will also greatly shorten the operation cycle of the device. The silicon powder content in the gas phase after the reaction is large, and the dust removal unit of the hydrogenation device and the downstream slurry treatment have high pressure. Summary of the Invention

[0004] Purpose of the Utility Model: The technical problem to be solved by the utility model is to provide a fluidized bed reactor aiming at the deficiencies of the existing technology, so as to reduce the content of fine powder in the cold hydrogenation fluidized bed and the risk of abnormal phenomena such as slugging and channeling.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A novel hydrochlorination-coupled fluidized bed reactor includes a fluidized bed reactor, a cyclone separator, and a hydrogen chloride gas distributor; a set of the cyclone separators is arranged in the upper part inside the fluidized bed reactor; the hydrogen chloride gas distributor is arranged in the middle part inside the fluidized bed reactor. The fine powder generated in the cold-hydrogenation fluidized bed is consumed through reaction in the dilute-phase section of the fluidized bed. HCl gas is introduced into the upper part of the reaction zone of the cold-hydrogenation fluidized bed to react with the fine granular silicon powder that has not participated in the main cold-hydrogenation reaction in the dilute-phase section, consuming the silicon powder contained in the fine powder.

[0007] Specifically, the hydrogen chloride gas distributor is arranged in the upper part of the main reaction zone of the fluidized bed reactor and is located below the cyclone separator, that is, in the reaction zone of the dilute-phase section of the fluidized bed.

[0008] Further, the hydrogen chloride gas distributor includes a set of horizontally arranged gas pipelines, and a set of air outlet holes are opened downward on the surface of each gas pipeline.

[0009] Further, the gas pipelines of the hydrogen chloride gas distributor include a main pipeline and a set of branch pipelines; the outer end of the main pipeline is connected to a hydrogen chloride gas source, and the other end extends into the interior of the fluidized bed reactor after passing through the inner wall of the fluidized bed; the branch pipelines are vertically fixed below the main pipeline at intervals and are communicated with the main pipeline.

[0010] Preferably, a set of air outlet holes are uniformly arranged downward on the surface of the branch pipelines. Hydrogen chloride is introduced into the upper part of the reaction zone of the dense-phase section of the fluidized bed. The air outlet holes of each branch of the hydrogen chloride gas distributor face downward, forming a cross-flow with the upward airflow in the fluidized bed, and hydrogen chloride reacts with the fine granular silicon powder entrained in the upward airflow in the fluidized bed.

[0011] Preferably, the installation height of the hydrogen chloride gas distributor is 0.5 - 1.5 m away from the main reaction zone.

[0012] Specifically, a feed pipe for introducing H 2 and SiCl 4 is connected to the bottom of the fluidized bed reactor.

[0013] Preferably, a pair of cyclone separators are oppositely arranged on both sides of the top of the fluidized bed reactor.

[0014] Preferably, the gas phase pipes of the cyclone separators are led out from the top of the fluidized bed reactor and are connected to a subsequent treatment system through a gas phase main pipe.

[0015] Further, a detector for monitoring the hydrogen chloride concentration is arranged on the gas phase main pipe.

[0016] Compared with the prior art, the present utility model has the following advantages:

[0017] The content of fine powder in the cold hydrofluosilation fluidized bed is reduced, greatly decreasing the probability of abnormal phenomena such as slugging and channeling in the fluidized bed. The fluidized bed achieves better dispersed fluidization, effectively increasing the stability of the fluidized bed and improving the product yield. The fine silicon powder is fully utilized, reducing the production cost. The fine powder is converted into trichlorosilane in the fine powder fluidized bed, and the overall yield of cold hydrofluosilation is improved. The content of solid particles in the gas phase entering the downstream is reduced, and the amount of fine powder adhering to the inner wall of the tube side of the waste heat recovery heat exchanger is decreased. The three-stage heat exchanger maintains good heat transfer efficiency, reducing power consumption and extending the operation cycle of the device. The workload of the downstream dust removal unit is reduced, and the risk of system blockage is lowered. The amount of waste residue treated by the slurry treatment device is decreased, reducing the waste residue treatment cost. The content of fine silicon powder that is prone to flash explosion in the waste residue is reduced, enhancing safety. Brief Description of the Drawings

[0018] The following further specifically describes the present utility model in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present utility model will become clearer.

[0019] Figure 1 It is a schematic diagram of the overall structure of the fluidized bed reactor.

[0020] Figure 2 It is a top view of the hydrogen chloride gas distributor in the fluidized bed reactor.

[0021] Among them, each reference numeral represents respectively:

[0022] 1 - fluidized bed reactor; 101 - feed pipe; 2 - cyclone separator; 201 - gas phase pipe; 3 - main reaction zone; 4 - hydrogen chloride gas distributor; 401 - main pipeline; 402 - branch pipeline; 403 - air outlet hole; 5 - inner wall of the fluidized bed; 6 - reaction zone in the dilute phase of the fluidized bed. Specific Embodiments

[0023] The present utility model can be better understood according to the following embodiments.

[0024] The structures, ratios, sizes, etc. shown in the drawings of the specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limited conditions under which the present utility model can be implemented. Therefore, they do not have technical essential significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present utility model can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed by the present utility model. At the same time, terms such as "upper", "lower", "front", "rear", "middle", etc. cited in this specification are only for the convenience of clear narration and are not used to limit the scope under which the present utility model can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present utility model can be implemented.

[0025] As shown Figure 1 in the figure, the utility model discloses a new type of chlorohydrogenation coupling fluidized bed reactor, which includes a fluidized bed reactor 1, a cyclone separator 2 and a hydrogen chloride gas distributor 4; the cyclone separator 2 is a group and is arranged in the upper part of the fluidized bed reactor 1; the hydrogen chloride gas distributor 4 is arranged in the middle of the fluidized bed reactor 1. The fine powder generated in the cold hydrogenation fluidized bed is consumed in the reaction in the dilute phase section of the fluidized bed. HCl gas is introduced into the upper part of the cold hydrogenation fluidized bed reaction zone to react with the fine particle silicon powder that has not participated in the main cold hydrogenation reaction in the dilute phase section, consuming the silicon powder contained in the fine powder.

[0026] In this embodiment, the hydrogen chloride gas distributor 4 is arranged above the main reaction zone 3 of the fluidized bed reactor 1 and is located below the cyclone separator 2, that is, the reaction zone 6 in the dilute phase section of the fluidized bed.

[0027] In this embodiment, the hydrogen chloride gas distributor 4 includes a group of horizontally arranged gas pipelines, and a group of air outlet holes 403 are opened downward on the surface of each gas pipeline.

[0028] In this embodiment, the gas pipelines of the hydrogen chloride gas distributor 4 include a main pipeline 401 and a group of branch pipelines 402; the outer end of the main pipeline 401 is connected to a hydrogen chloride gas source, and the other end extends into the fluidized bed reactor 1 after passing through the inner wall 5 of the fluidized bed; the branch pipelines 402 are vertically fixed at intervals below the main pipeline 401 and are communicated with the main pipeline 401.

[0029] In this embodiment, a group of air outlet holes 403 are uniformly arranged downward on the surface of the branch pipeline 402. Hydrogen chloride is introduced into the upper part of the dense phase section reaction zone of the fluidized bed. The air outlet holes of each branch of the hydrogen chloride gas distributor face downward, forming a cross flow with the upward airflow in the fluidized bed, and hydrogen chloride reacts with the fine particle silicon powder entrained in the upward airflow in the fluidized bed.

[0030] In this embodiment, the installation height of the hydrogen chloride gas distributor 4 is about 1 m away from the main reaction zone 3.

[0031] In this embodiment, the bottom of the fluidized bed reactor 1 is connected with a feed pipe 101 for introducing H 2 and SiCl 4 .

[0032] In this embodiment, the cyclone separator 2 is a pair and is relatively arranged on both sides of the top of the fluidized bed reactor 1.

[0033] In this embodiment, the gas phase pipe 201 of the cyclone separator 2 is led out from the top of the fluidized bed reactor 1 and is connected to a subsequent treatment system through a gas phase main pipe.

[0034] In this embodiment, a detector for monitoring the hydrogen chloride concentration is provided on the gas main pipe. After hydrogen chloride is introduced into the fluidized bed reactor 1, the hydrogen chloride content in the gas in the gas main pipe at the top of the fluidized bed reactor 1 is detected, and the flow rate of hydrogen chloride entering the fluidized bed reactor 1 is adjusted according to the hydrogen chloride content. If the hydrogen chloride content in the detected gas is high, the hydrogen chloride flow rate is reduced; if there is no or low hydrogen chloride content in the detected gas, the hydrogen chloride flow rate is increased.

[0035] By passing hydrogen chloride gas through the reaction zone 6 in the dilute phase section of the fluidized bed of the fluidized bed reactor, the silicon powder in the fine powder is reacted, the utilization rate of the silicon powder is improved, the cost is reduced, and the product yield is increased. The pressure of the dust removal system downstream of the cold hydrogenation and the slurry treatment cost are effectively reduced, the content of fine silicon powder that is prone to flash explosion in the waste residue is reduced, and the safety is improved.

[0036] The present utility model provides an idea and method for a novel chlorine-hydrogenation coupled fluidized bed reactor. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model. Each component not clearly defined in this embodiment can be realized by the prior art.

Claims

1. A novel hydrochlorination coupled fluidized bed reactor, characterized in that: It comprises a fluidized bed reactor (1), a cyclone separator (2) and a hydrogen chloride gas distributor (4); the cyclone separator (2) is a group and is arranged in the upper part of the fluidized bed reactor (1); the hydrogen chloride gas distributor (4) is arranged in the middle part of the fluidized bed reactor (1).

2. The novel hydrochlorination coupled fluidized bed reactor according to claim 1, characterized in that: The hydrogen chloride gas distributor (4) is arranged at the upper part of the main reaction zone (3) of the fluidized bed reactor (1) and is located below the cyclone separator (2).

3. The novel hydrochlorination coupled fluidized bed reactor according to claim 1, characterized in that: The hydrogen chloride gas distributor (4) comprises a group of horizontally arranged gas pipelines, each gas pipeline having a group of gas outlet holes (403) opened downward on its surface.

4. The novel hydrochlorination coupled fluidized bed reactor according to claim 3, characterized in that: The gas pipeline of the hydrogen chloride gas distributor (4) comprises a main pipeline (401) and a group of branch pipelines (402); the outer end of the main pipeline (401) is connected to the hydrogen chloride gas source, and the other end passes through the inner wall of the fluidized bed (5) and extends into the fluidized bed reactor (1); the branch pipelines (402) are arranged at intervals and vertically fixed below the main pipeline (401), and are connected to the main pipeline (401).

5. The novel hydrochlorination coupled fluidized bed reactor according to claim 4, characterized in that: A group of air outlet holes (403) are evenly arranged on the surface of the branch pipe (402) facing downward.

6. The novel hydrochlorination coupled fluidized bed reactor according to claim 2, characterized in that: The hydrogen chloride gas distributor (4) is arranged at a height of 0.5 to 1.5 m from the main reaction zone (3).

7. The novel hydrochlorination coupled fluidized bed reactor according to claim 1, characterized in that: The bottom of the fluidized bed reactor (1) is connected to a feed pipe (101) for introducing H2 and SiCl4.

8. The novel hydrochlorination coupled fluidized bed reactor according to claim 1, characterized in that: The cyclone separators (2) are a pair, arranged opposite to each other on two sides of the top of the fluidized bed reactor (1).

9. The novel hydrochlorination coupled fluidized bed reactor according to claim 8, characterized in that: The gas phase pipe (201) of the cyclone separator (2) is led out from the top of the fluidized bed reactor (1) and is connected to a subsequent processing system via a gas phase main pipe.

10. The novel hydrochlorination coupled fluidized bed reactor according to claim 9, characterized in that: The gas phase main pipe is provided with a detector for monitoring the concentration of hydrogen chloride.

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