Vapor phase impurity removal system of polycrystalline silicon slurry drying machine
By introducing purification towers and multi-stage condensers into the polycrystalline silicon slurry dryer, the problem of pipeline blockage caused by impurities in the gas-phase chlorosilane is solved, the equipment cleaning cycle is extended, and the system operation efficiency is improved.
Patent Information
- Application Number
- CN202510707507.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-07-18
AI Technical Summary
In existing polycrystalline silicon slurry dryers, gas-phase chlorosilane contains metal chloride and silicon powder, which causes pipelines and condensers to be scaled and frequently blocked, reducing the system operation cycle and increasing the maintenance frequency.
Using a purification tower and a multi-stage condensation mechanism, the purification tower removes impurities in the gas-phase chlorosilane by spraying, and the multi-stage condenser realizes cooling and condensation to reduce impurity deposition.
It reduces the maintenance frequency of the steam-phase outlet pipeline of the dryer, extends the cleaning cycle, and improves the system operation efficiency.
Smart Images
Figure CN120328565A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vapor phase impurity removal system for a polysilicon slurry dryer, belonging to the technical field of polysilicon slurry treatment. Background Art
[0002] Please refer to Figure 1 , the process flow of the existing polysilicon slurry dryer is as follows: In the dryer 1, steam enters the dryer 1 through the pipeline 12, and the exhausted steam and a small amount of steam condensate after steam heating are discharged through the pipeline 13. The solid waste after the slurry is filtered by the drum or filter is dried in the dryer 1. After being heated by steam, the chlorosilane in the solid waste vaporizes, and the formed gaseous chlorosilane reaches the gas phase condenser 8 through the pipeline 14 and condenses into a liquid.
[0003] However, since some of the metal chlorides contained in the solid waste are vaporized during the drying of the solid waste, a small amount of vaporized metal chlorides are contained in the gaseous chlorosilane. At the same time, some fine silicon powder is entrained by the vaporized chlorosilane gas and carried out of the dryer 1. These metal chlorides precipitate after being cooled by the pipeline 14 and the condenser 8, and are deposited inside the pipeline 14 and the gas phase condenser 8. The deposited metal chlorides and the silicon powder entrained by the gaseous chlorosilane are mixed to form scale on the inner walls of the pipeline 14 and the gas phase condenser 8, and the scale blocks the gas phase pipeline 14 and the gas phase condenser 8. In some specific use environments, the operation time of the vapor phase outlet pipeline does not exceed 1 month, and the operation time of the gas phase condenser tube bundle blockage does not exceed 3 months before it is necessary to stop the machine for cleaning. Therefore, it is necessary to frequently disassemble and clean the vapor phase outlet pipeline and the gas phase condenser, which reduces the system operation cycle and increases the maintenance frequency and maintenance cost. Summary of the Invention
[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a vapor phase impurity removal system for a polysilicon slurry dryer, aiming to reduce blockage caused by impurities through impurity removal and multi-stage cooling of gaseous chlorosilane.
[0005] To achieve the above purpose, the present invention is implemented by the following technical solutions: The present invention provides a vapor phase impurity removal system for a polysilicon slurry dryer, including: A dryer for accommodating solids containing chlorosilane and obtaining gaseous chlorosilane by heating the solids with steam; A purification tower, the inlet of which is connected to the top outlet of the dryer; the purification tower is used to remove impurities in the gaseous chlorosilane by spraying to obtain the impurity-removed gaseous chlorosilane and the liquid with impurities; A multi-stage condensation mechanism, the inlet of which is connected to the top outlet of the purification tower; the multi-stage condensation mechanism is used to receive the gaseous chlorosilane output from the purification tower and condense the gaseous chlorosilane to obtain liquid chlorosilane.
[0006] Furthermore, the multi-stage condensation mechanism includes: A primary cooler, whose inlet is connected to the top outlet of the purification tower; A secondary condenser, whose inlet is connected to the gas outlet of the primary cooler; The primary cooler and the secondary condenser are used to sequentially condense the gaseous chlorosilane to obtain liquid chlorosilane.
[0007] Furthermore, it also includes a condensate tank; The bottom outlet of the purification tower, the liquid outlet of the primary cooler, and the liquid outlet of the secondary condenser are all connected to the inlet of the condensate tank; the condensate tank is used to collect the liquid in the purification tower and the liquid chlorosilane obtained by condensation from the primary cooler and the secondary condenser.
[0008] Furthermore, the gas outlet of the secondary condenser is connected to a cryogenic unit through a tail gas pipeline.
[0009] Furthermore, the liquid outlet of the condensate tank is connected to one end of a first transfer pipe; The other end of the first transfer pipe is connected to a slurry tank and is used to transfer a part of the liquid in the condensate tank to the slurry tank.
[0010] Furthermore, the liquid outlet of the condensate tank is also connected to one end of a second transfer pipe, and the other end of the second transfer pipe is connected to a spray cooler; and it is used to transfer a part of the liquid in the condensate tank to the spray cooler; the spray cooler is used to cool the liquid transported from the second transfer pipe and then continue it to the purification tower as spray liquid.
[0011] Furthermore, the liquid outlet of the condensate tank is connected to the inlet of a residue pump, and the outlet of the residue pump is connected to one end of the first transfer pipe and one end of the second transfer pipe.
[0012] Furthermore, an input pipe for inputting a heating medium is connected to the inlet of the dryer.
[0013] Furthermore. The heating medium is hot water or superheated water, and the temperature value of the hot water or superheated water is 90 - 180 °C.
[0014] Furthermore, the heating medium is saturated steam or superheated steam, and the temperature value of the saturated steam or superheated steam is 100 - 180 °C.
[0015] Compared with the prior art, the beneficial effects achieved by the present invention: The present invention provides a vapor phase impurity removal system for a polysilicon slag slurry dryer. By setting up a purification tower, the inlet of the purification tower is connected to the top outlet of the dryer; the purification tower is used to remove impurities in the vapor phase chlorosilane by spraying, so as to obtain the impurity-removed vapor phase chlorosilane and the liquid with impurities. The purification tower can remove impurities from the vapor phase chlorosilane, thereby directly reducing the impact of impurities on subsequent equipment.
[0016] The present invention also sets up a multi-stage condensation mechanism after the purification tower. Both the multi-stage condensation mechanism and the purification tower can achieve the cooling and condensation of the vapor phase chlorosilane. Therefore, the length of the pipeline between the dryer and the purification tower can be designed to be the shortest length when meeting the requirements, and the impurity deposition caused by the cooling of the vapor phase chlorosilane in this pipeline can also be reduced. Therefore, the present invention can significantly reduce the maintenance frequency of the vapor phase outlet pipeline of the dryer. Due to the impurity removal operation of the purification tower, the multi-stage condensation mechanism does not need to stop for maintenance and cleaning of scale, and the overall operation efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a schematic structural diagram of a vapor phase impurity removal system for a polysilicon slag slurry dryer in the prior art; Figure 2 is a schematic structural diagram of a vapor phase impurity removal system for a polysilicon slag slurry dryer provided by an embodiment of the present invention; In the figure: 1, dryer; 11, first pipeline; 12, input pipe; 13, discharge pipe; 14, cooling pipe; 2, purification tower; 21, liquid delivery pipe; 22, second pipeline; 3, condensate tank; 31, residual liquid delivery pipe; 32, return air pipe; 4, residual liquid pump; 41, first delivery pipe; 42, second delivery pipe; 5, spray cooler; 51, return liquid pipe; 6, primary cooler; 61, third pipeline; 62, fourth pipeline; 7, secondary condenser; 71, fifth pipeline; 72, tail gas pipeline; 8, vapor phase condenser; 81, condenser drain pipe; 82, condenser exhaust pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0018] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.
[0019] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.
[0020] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances. Embodiment
[0021] Please refer to Figure 2 , this embodiment introduces a vapor phase impurity removal system for a polysilicon slurry dryer, including a dryer 1, a purification tower 2, and a multi-stage condensation mechanism.
[0022] Among them, the solid waste residue after the polysilicon slurry is filtered by a rotary drum or a filter is dried in a dryer 1. After being heated by steam, the chlorosilane in the solid waste residue vaporizes to form gaseous chlorosilane. Since some of the metal chlorides contained in the solid waste residue are vaporized during the drying of the solid waste residue, a small amount of vaporized metal chlorides are contained in the gaseous chlorosilane. At the same time, some fine silicon powder is entrained out of the dryer 1 by the vaporized chlorosilane gas. The inlet of the purification tower 2 is connected to the top outlet of the dryer 1 through a first pipeline 11; the purification tower 2 is used to remove impurities in the gaseous chlorosilane by spraying to obtain the purified gaseous chlorosilane and the liquid with impurities. Since the purification tower can realize the cooling and condensation of the gaseous chlorosilane, the length of the first pipeline 11 between the dryer 1 and the purification tower 2 can be designed to be the shortest length when meeting the necessary requirements, thereby reducing the impurity deposition caused by the cooling of the gaseous chlorosilane in the first pipeline 11 due to the long pipeline length. The inlet of the multi-stage condensation mechanism is connected to the top outlet of the purification tower 2; the multi-stage condensation mechanism is used to receive the gaseous chlorosilane output from the purification tower 2 and condense the gaseous chlorosilane to obtain liquid chlorosilane.
[0023] Specifically, in this embodiment, the multi-stage condensation mechanism includes a primary cooler 6 and a secondary condenser 7. The inlet of the primary cooler is connected to the top outlet of the purification tower 2 through a second pipeline 22. The inlet of the secondary condenser 7 is connected to the gas outlet of the primary cooler 6 through a fourth pipeline 62. The primary cooler 6 and the secondary condenser 7 are used to condense the gaseous chlorosilane in sequence to obtain liquid chlorosilane.
[0024] In addition, in order to collect the liquid chlorosilane, a condensate tank 3 is provided in this embodiment. The bottom outlet of the purification tower 2 is connected to the inlet of the condensate tank 3 through an infusion pipe 21. The liquid outlet of the primary cooler 6 is connected to the inlet of the condensate tank 3 through a second pipeline 61. The liquid outlet of the secondary condenser 7 is connected to the inlet of the condensate tank 3 through a fifth pipeline 71; the condensate tank 3 is used to collect the liquid in the purification tower 2 and the liquid chlorosilane condensed by the primary cooler 6 and the secondary condenser 7.
[0025] Further, the liquid outlet of the condensate tank 3 is connected to one end of the first delivery pipe 41; the other end of the first delivery pipe 41 is connected to a slurry tank (not shown in the figure) and is used to deliver a part of the liquid in the condensate tank 3 to the slurry tank. The liquid outlet of the condensate tank 3 is also connected to one end of the second delivery pipe 42, and the other end of the second delivery pipe 42 is connected to the spray cooler 5; and it is used to deliver another part of the liquid in the condensate tank 3 to the spray cooler 5; the spray cooler 5 is used to cool the liquid delivered from the second delivery pipe 42 and continue to deliver it to the purification tower 2 through the return pipe 51 for use as spray liquid. Among them, the liquid chlorosilane for spraying is cooled by the spray cooler 5, and the temperature of the sprayed chlorosilane is -25 - 30 °C. Preferably, the temperature of the sprayed chlorosilane can be -20 ~ 15 °C. The gas outlet of the condensate tank 3 is connected to the fourth pipe 62 through the return pipe 32, so as to return the generated gas to the secondary condenser 7 for condensation.
[0026] It should be added that, please refer to Figure 2 , in order to improve the output efficiency of the liquid in the condensate tank 3, in this embodiment, the liquid outlet of the condensate tank 3 is connected to the inlet of the residue pump 4 through the residue delivery pipe 31, and the outlet of the residue pump 4 is connected to one end of the first delivery pipe 41 and one end of the second delivery pipe 42.
[0027] It should be noted that the drying temperature of the dryer is 90 - 180 °C, and the inlet of the dryer 1 is connected to the input pipe 12 for inputting the heating medium. In this embodiment, the heating medium input through the input pipe 12 is steam, and the steam is saturated steam or superheated steam, and the temperature value of the saturated steam or superheated steam is 100 - 180 °C. The bottom outlet of the dryer 1 is connected with a discharge pipe 13 for discharging the waste steam and steam condensate generated after heating the steam in the dryer 1.
[0028] In addition, in other embodiments, the steam can be replaced by hot water, and the hot water is hot water with a temperature value of 90 - 100 °C or superheated water with a temperature value of 100 - 160 °C. After being heated in the dryer 1, the hot water can be discharged from the discharge pipe 13.
[0029] Among them, preferably, superheated water at 130 °C - 155 °C is used. After heating the dryer 1, it is used as the cooling water for cooling to a higher temperature or as the makeup water for the flash tank that generates steam by flashing superheated water.
[0030] It should be noted that in the specific implementation, the present invention greatly reduces the maintenance frequency of the first pipe 11 at the vapor outlet of the dryer 1. The cleaning cycle of the first pipe 11 is reduced from less than 1 month to regular cleaning once a year, and the primary cooler 6 and secondary condenser 7 no longer need to be shut down for maintenance and cleaning of scale, greatly improving the production efficiency. Embodiment
[0031] This embodiment provides a vapor phase impurity removal system for a polysilicon slurry dryer, which is different from that of Embodiment 1. In this embodiment, a tail gas pipeline 72 is connected to a cryogenic unit at the gas outlet of the secondary condenser 7, so that the tail gas that fails to be condensed in the secondary condenser 7 is transported through the tail gas pipeline 72 to the cryogenic unit for further condensation.
[0032] In addition, the cryogenic unit can be replaced with a tail gas treatment unit for further treatment of the waste gas.
[0033] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.
[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than to limit the scope of its protection. Although the present disclosure has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the present disclosure, various changes, modifications or equivalent replacements can still be made to the specific implementation manners of the invention, but these changes, modifications or equivalent replacements are all within the protection scope of the claims pending for the disclosure.
Claims
1. A vapor phase impurity removal system for a polysilicon slurry dryer, characterized in that, Comprising: A dryer for containing solids containing chlorosilane and heating the solids with steam to obtain gaseous chlorosilane; A purification tower, the inlet of which is connected to the top outlet of the dryer; the purification tower is used to remove impurities in the gaseous chlorosilane by spraying to obtain the impurity-removed gaseous chlorosilane and the liquid with impurities; A multi-stage condensation mechanism, the inlet of which is connected to the top outlet of the purification tower; the multi-stage condensation mechanism is used to receive the gaseous chlorosilane output from the purification tower and condense the gaseous chlorosilane to obtain liquid chlorosilane.
2. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 1, wherein, The multi-stage condensation mechanism includes: A primary cooler, the inlet of which is connected to the top outlet of the purification tower; A secondary condenser, the inlet of which is connected to the gas outlet of the primary cooler; The primary cooler and the secondary condenser are used to sequentially condense the gaseous chlorosilane to obtain liquid chlorosilane.
3. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 2, wherein It further includes a condensate tank; The bottom outlet of the purification tower, the liquid outlet of the primary cooler and the liquid outlet of the secondary condenser are all connected to the inlet of the condensate tank; the condensate tank is used to collect the liquid in the purification tower and the liquid chlorosilane condensed by the primary cooler and the secondary condenser.
4. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 2, characterized in that, The gas outlet of the secondary condenser is connected to a cryogenic unit through a tail gas pipeline.
5. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 1, characterized in that, The liquid outlet of the condensate tank is connected to one end of a first conveying pipe; The other end of the first conveying pipe is connected to a slurry tank and is used to convey a part of the liquid in the condensate tank to the slurry tank.
6. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 5, characterized in that, The liquid outlet of the condensate tank is also connected to one end of a second conveying pipe, and the other end of the second conveying pipe is connected to a spray cooler; and it is used to convey a part of the liquid in the condensate tank to the spray cooler; the spray cooler is used to cool the liquid conveyed from the second conveying pipe and convey it to the purification tower as spray liquid.
7. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 6, wherein The liquid outlet of the condensate tank is connected to the inlet of a residue pump, and the outlet of the residue pump is connected to one end of the first conveying pipe and one end of the second conveying pipe.
8. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 1, wherein An input pipe for inputting a heating medium is connected to the inlet of the dryer.
9. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 8, wherein, The heating medium is hot water or superheated water, and the temperature value of the hot water or superheated water is 90 - 180 °C.
10. The vapor phase impurity removal system of the polysilicon slurry dryer according to claim 8, characterized in that, The heating medium is saturated steam or superheated steam, and the temperature value of the saturated steam or superheated steam is 100 - 180 °C.