Polycrystalline silicon cold hydrogenation slurry high-boiling recovery system and recovery method thereof

Abstract

The invention discloses a polycrystalline silicon cold hydrogenation slurry high-boiling recovery system and a recovery method thereof. The polycrystalline silicon cold hydrogenation slurry high-boiling recovery system comprises a solid-liquid separation device, a separation and purification device and a high-boiling cracking device, the solid-liquid separation device comprises a flash evaporation cooling tank, a vacuum filter, a clear liquid tank and a flash evaporation condenser which are connected through pipelines; the separation and purification device comprises a rectifying tower, a tower top water cooler, a tower top deep freezer, a tower top tail gas supercharger and a return tank which are connected through a pipeline; the high-boiling cracking device comprises a feeding cooler, a filter and a high-boiling reactor which are connected through a pipeline, a rectifying tower is used for separating and recycling slag slurry clear liquid and cracking products at the same time, the equipment utilization rate is increased, the equipment investment is reduced, and then the construction cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of high boiling point recovery of polysilicon cold hydrogenation slag slurry, and in particular relates to a high boiling point recovery system and a recovery method of polysilicon cold hydrogenation slag slurry. Background Art

[0002] In the process of implementing the present invention, the inventors found that the prior art has at least the following problems:

[0003] Patent CN202010351447- Cracking process of high-boiling chlorosilane by-products in polysilicon production discloses filtering high-boiling chlorosilane by-products in polysilicon production to remove amorphous silicon, then using a catalyst to crack hydrogen chloride and purified high-boiling products to obtain a cracking product system, and then separating and recovering the cracking product system through a distillation tower. However, this method requires preheating before cracking, and the cracking product system must be cooled and condensed before being sent to a distillation tower for separation. This method has the problems of high energy consumption and insufficient heat utilization. In addition, the device of this method only processes high-boiling products alone, and the utilization rate of the device is insufficient. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a polysilicon cold hydrogenation slag high boiling point recovery system and a recovery method thereof, which utilizes a distillation tower to simultaneously separate and recover the slag slurry clear liquid and cracking products, thereby improving equipment utilization, reducing equipment investment, and thus reducing construction costs.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a polysilicon cold hydrogenation slag slurry high boiling point recovery system, having:

[0006] It includes a solid-liquid separation device, a separation and purification device and a high-boiling cracking device;

[0007] The solid-liquid separation device comprises a flash cooling tank, a vacuum filter, a clear liquid tank and a flash condenser connected by pipelines;

[0008] The separation and purification device comprises a distillation tower, a tower top water cooler, a tower top deep cooler, a tower top tail gas booster, and a reflux tank connected by pipelines;

[0009] The high boiling cracking device comprises a feed cooler, a filter and a high boiling reactor connected by pipelines.

[0010] The distillation tower is connected to the top water cooler through a gas phase pipeline, the top water cooler is connected to the top deep freezer through a gas phase outlet pipeline, the top deep freezer is connected to the top tail gas booster through a gas phase pipeline, the top tail gas booster is connected to the high boiling cracking device through a gas phase outlet pipeline, and the distillation tower is connected to the high boiling cracking device through a bottom discharge pipeline.

[0011] The reflux tank receives liquid materials from the tower top water cooler and the tower top deep cooler through a liquid feed pipe; the reflux tank returns the liquid materials to the distillation tower for reflux through a liquid discharge pipe, and extracts the liquid materials through an extraction pipeline and sends them to the hydrogenation system for recycling.

[0012] The distillation tower receives the cracking product of the high-boiling cracking unit through a gas phase feed pipeline.

[0013] The feed cooler is connected to the distillation tower via a tower bottom discharge pipeline, and the filter and the high boiling reactor are sequentially connected to the downstream of the feed cooler.

[0014] The high boiling reactor receives gas from the tail gas booster at the top of the tower through a gas phase pipeline, receives high boiling products from the bottom of the distillation tower through a high boiling pipeline, and the gas generated by the reaction is sent to the distillation tower through the gas phase pipeline for separation and purification.

[0015] The top of the high boiling reactor is provided with a silicon tetrachloride feeding pipeline, and the bottom is provided with a residual discharge pipeline connected with the feeding port of the flash cooling tank.

[0016] The invention also comprises a neutralization treatment device, which is a neutralization tank connected with a filter.

[0017] The above-mentioned recovery method of the polysilicon cold hydrogenation slag slurry high boiling point recovery system comprises the following steps:

[0018] 1) Discharge the cold hydrogenated slag slurry into a flash cooling tank for flash evaporation to obtain a first gas phase and a first slurry, control the flash pressure at 0.01-0.1 MPa, the temperature of the first slurry at 30-50°C, and the liquid level at 20-60%; condense the first gas phase through a flash condenser to obtain a first clear liquid, which is sent to a clear liquid tank for buffering, and control the temperature of the first clear liquid at -10--30°C; separate the first slurry into a first solid slag and a second clear liquid through a vacuum drum filter for solid-liquid separation, and send the first solid slag to a neutralization tank through a solid slag discharge pipeline for treatment and then discharge, and send the second clear liquid to a clear liquid tank and mix it with the first clear liquid to obtain a third clear liquid;

[0019] 2) The third clear liquid is sent to a distillation tower for separation, and a second gas phase containing light component chlorosilane is obtained at the top of the tower, and a high-boiling product of chlorosilane is obtained at the bottom of the tower. The pressure at the top of the tower is controlled to be 0.1-0.2MPa, the temperature is 60-80°C, and the pressure at the bottom of the tower is 0.15-0.25MPa, and the temperature is 80°C-100°C; the second gas phase is condensed by a water cooler at the top of the tower and a deep cooler at the top of the tower to obtain a fourth clear liquid and a third gas phase, and the temperature of the third gas phase is controlled to be -10--30°C and the pressure is 0.08-0.18MPa. A part of the fourth clear liquid is used as a reflux at the top of the distillation tower, and the other part is sent back to the cold hydrogenation system for reuse. The third gas phase is pressurized by a tail gas booster at the top of the tower to obtain a fourth gas phase, and the fourth gas phase is sent to the bottom of the high-boiling reactor to participate in the reaction, and the temperature of the fourth gas phase is controlled to be 70-90°C and the pressure is 0.15-0.25Mpa;

[0020] 3) The high-boiling chlorosilanes are sent to a high-boiling reactor to participate in the reaction after the temperature is controlled at 70-95° C. by a feed cooler. A filter is set before the high-boiling chlorosilanes enter the high-boiling reactor. The filter removes fine silicon powder and metal chloride in the high-boiling chlorosilanes, and the high-boiling chlorosilanes are sent to a neutralization tank for treatment; the high-boiling chlorosilanes and the fourth gas phase undergo a cracking reaction in the high-boiling reactor to obtain a fifth gas phase containing light-component chlorosilanes, and the reaction temperature is indirectly controlled at 70-100° C. by a feed cooler, and the reaction pressure is controlled at 0.1-0.25 MPa; the fifth gas phase is sent to a distillation tower to separate and recover the light-component chlorosilanes therein, and the unreacted high-boiling chlorosilanes are sent to the high-boiling reactor again through the bottom of the tower to continue to participate in the reaction;

[0021] 4) A silicon tetrachloride elution pipeline is added to the top of the high boiling reactor. When the conversion rate of high boiling silane is lower than 75%, 3-4 t / h of silicon tetrachloride is used to continuously wash the catalyst from top to bottom for 20-40 minutes through the silicon tetrachloride elution pipeline to wash the fine silicon powder off the catalyst surface. The washed fine silicon powder and silicon tetrachloride are discharged to the flash cooling tank through the residual discharge pipeline at the bottom of the high boiling reactor, and finally filtered out through the vacuum drum cake layer, and the silicon tetrachloride used for washing is recovered.

[0022] One of the above technical solutions has the following advantages or beneficial effects: a distillation tower is used to simultaneously separate and recover the slurry clear liquid and the cracking product, thereby improving equipment utilization, reducing equipment investment, and thus reducing construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a high boiling point recovery system for polysilicon cold hydrogenation slag slurry provided in an embodiment of the present invention;

[0024] The marks in the above figure are:

[0025] 01. Flash cooling tank, 02. Vacuum filter, 03. Clear liquid tank, 04. Flash condenser,

[0026] 05. Distillation tower, 06. Tower top water cooler, 07. Tower top deep cooler, 08. Tower top tail gas booster, 09. Reflux tank,

[0027] 10. Feed cooler, 11. Filter, 12. High boiling reactor,

[0028] 13. Neutralization tank.

[0029] 011, cold hydrogenation slag slurry, 012, first gas phase, 013, first slag slurry; 041, first clear liquid, 021, second clear liquid, 022, first solid slag, 031, third clear liquid, 052, second gas phase, 053, high-boiling chlorosilane, 071, third gas phase, 091, fourth clear liquid, 081, fourth gas phase, 121, fifth gas phase, 122, silicon tetrachloride elution. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 A high-boiling recovery system for polysilicon cold hydrogenation slag slurry comprises: a solid-liquid separation device, a separation and purification device and a high-boiling cracking device; the solid-liquid separation device comprises a flash cooling tank 01, a vacuum filter 02, a clear liquid tank 03 and a flash condenser 04 connected by pipelines; the separation and purification device comprises a distillation tower 05, a tower top water cooler 06, a tower top deep cooler 07, a tower top tail gas booster 08, and a reflux tank 09 connected by pipelines; the high-boiling cracking device comprises a feed cooler 10, a filter 11 and a high-boiling reactor 12 connected by pipelines.

[0032] The residual liquid of the cold hydrogenated slag slurry 011 is connected to the flash cooling tank 01 through a residual discharge pipeline, the flash cooling tank 01 is connected to the vacuum filter 02 through a slurry discharge pipeline, and the vacuum filter 02 is connected to the clear liquid tank 03 through a two-phase flow pipeline; the flash cooling tank 01 is connected to the flash condenser 04 through a gas phase pipeline, the flash condenser 04 is connected to the clear liquid tank 03 through a pipeline, and the clear liquid tank 03 is connected to the separation and purification device through the clear liquid pipeline; the vacuum filter 02 is provided with a solid slag discharge port, which is connected to the neutralization treatment device through a solid slag discharge pipeline;

[0033] The cold hydrogenated slag slurry 011 can be separated into solid and liquid by the solid-liquid separation device to obtain a clear liquid and a solid slag. The clear liquid is recycled after separation and purification, thereby improving the utilization rate of the silicon element and reducing the production cost. The solid slag is discharged after neutralization treatment, thereby reducing the generation of wastewater and reducing the cost of wastewater treatment.

[0034] The flash cooling tank 01 is provided with a circulating water cooling jacket for cooling the slurry in the tank, which is beneficial to the precipitation of metal chlorides in the slurry.

[0035] Through the above-mentioned structural setting, the metal chloride in the slurry is precipitated so as to be separated by the vacuum filter 02, thereby avoiding the enrichment of the metal chloride in the system, improving the separation and purification effect, extending the use time of the cracking reaction catalyst, and thus improving production efficiency and reducing production costs.

[0036] The separation and purification device includes a distillation tower 05, a top water cooler 06, a top deep freezer 07, a top tail gas booster 08, and a reflux tank 09. The distillation tower 05 is connected to the clear liquid tank 03 through a liquid phase pipeline to receive the clear liquid from the clear liquid tank 03; the distillation tower 05 is connected to the top water cooler 06 through a gas phase pipeline, the top water cooler 06 is connected to the top deep freezer 07 through a gas phase outlet pipeline, the top deep freezer 07 is connected to the top tail gas booster 08 through a gas phase pipeline, the top tail gas booster 08 is connected to the high boiling point cracking device through a gas phase outlet pipeline, and the distillation tower 05 is connected to the high boiling point cracking device through a bottom discharge pipeline.

[0037] The reflux tank 09 receives liquid materials from the tower top water cooler 06 and the tower top deep cooler 07 through the liquid phase feed pipe, and returns the liquid materials to the distillation tower 05 for reflux through the liquid phase discharge pipe, and extracts part of the liquid materials through the extraction pipeline and sends them to the hydrogenation system for recycling; the distillation tower 05 receives the cracking products of the high-boiling cracking device through the gas phase feed pipeline, and separates and recovers the cracking products.

[0038] Through the above structural setting, a distillation tower 05 is used to separate and recover the slurry clear liquid and the cracking product at the same time, thereby improving the equipment utilization rate, reducing equipment investment, and further reducing construction costs.

[0039] The high-boiling cracking device includes a feed cooler 10, a filter 11, and a high-boiling reactor 12; the feed cooler 10 is connected to the bottom of the distillation tower 05 through a bottom discharge pipeline, and the filter 11 and the high-boiling reactor 12 are connected in sequence downstream of the feed cooler 10; the high-boiling reactor 12 receives the gas from the top tail gas booster 08 through a gas phase pipeline, and receives the high-boiling substances from the bottom of the distillation tower 05 through a high-boiling pipeline, and the gas generated by the reaction is sent to the distillation tower 05 through the gas phase pipeline for separation and purification.

[0040] Through the above-mentioned structural arrangement, the heat of the high-boiling materials in the distillation tower 05 kettle is fully utilized to provide heat for high-boiling cracking, thereby achieving the purpose of energy saving. When the temperature of the high-boiling reactor is too high, the high-boiling materials can be cooled by adjusting the load of the feed cooler 10, thereby achieving the purpose of controlling the reaction temperature of the high-boiling reactor and making the reaction more stable. In addition, a filter 11 is arranged before the high-boiling reactor 12 to remove metal chlorides precipitated from the high-boiling materials, reduce the influence of metal chlorides on the service life of the catalyst, and thus save production and maintenance costs.

[0041] A silicon tetrachloride feed pipeline is arranged at the top of the high boiling reactor 12, and a residual discharge pipeline is arranged at the bottom to be connected to the feed port of the flash cooling tank 01. Through the above-mentioned structural arrangement, when the high boiling cracking conversion rate decreases, the silicon tetrachloride is sprayed from the top of the high boiling reactor 12 to clean and remove the fine silicon powder and other microparticles attached to the catalyst surface from the catalyst surface, thereby restoring the effective specific surface area of ​​the catalyst, extending the service life of the catalyst, and thus saving production costs and maintenance costs. The residual liquid after cleaning is sent to the flash cooling tank 01 through the residual discharge pipeline at the bottom of the high boiling reactor 12, and then the microparticles therein are removed by the vacuum filter 02 to prevent the microparticles from being enriched in the system, improve the separation and purification effect, and extend the use time of the cracking reaction catalyst, thereby improving production efficiency and reducing production costs.

[0042] The neutralization treatment device includes a neutralization tank 13, which can receive the solid residue from the vacuum filter 02 and the filter 11, and is provided with a stirrer. After the neutralization reaction materials are fully stirred, they are sent out through an external pipeline. The above-mentioned structural setting makes the neutralization reaction more stable, while reducing the amount of wastewater generated by the treatment of solid residues and reducing production costs.

[0043] The above-mentioned polysilicon cold hydrogenation slag slurry 011 high boiling point recovery system recovery method comprises the following steps:

[0044] 1) The cold hydrogenated slag slurry 011 is discharged to the flash cooling tank 01 for flash evaporation to obtain the first gas phase 012 and the first slurry 013, and the flash pressure is controlled at 0.01-0.1 MPa, the temperature of the first slurry 013 is 30-50°C, and the liquid level is 20-60%; the first gas phase 012 is condensed by the flash condenser 04 to obtain the first clear liquid 041 which is sent to the clear liquid tank 03 for buffering, and the temperature of the first clear liquid 041 is controlled at -10--30°C; the first slurry 013 is subjected to solid-liquid separation by a vacuum drum filter to obtain the first solid slag 022 and the second clear liquid 021, the first solid slag 022 is sent to the neutralization tank 13 through the solid slag discharge pipeline for treatment and then discharged, and the second clear liquid 021 is sent to the clear liquid tank 03 to mix with the first clear liquid 041 to obtain the third clear liquid 031;

[0045] 2) The third clear liquid 031 is sent to a distillation tower 05 for separation, and a second gas phase 052 containing light chlorosilane components is obtained at the top of the tower, and a chlorosilane high boiling product 053 is obtained at the bottom of the tower. The pressure at the top of the tower is controlled to be 0.1-0.2 MPa, and the temperature is 60-80°C, and the pressure at the bottom of the tower is controlled to be 0.15-0.25 MPa, and the temperature is 80°C-100°C; the second gas phase 052 is condensed by a tower top water cooler 06 and a tower top deep cooler 07 to obtain a fourth clear liquid 091 and a third gas phase 071, and the first gas phase 052 is controlled to be The temperature of the third gas phase 071 is -10~-30℃, and the pressure is 0.08~0.18MPa. A part of the fourth clear liquid 091 is used as the top reflux of the distillation tower 05, and the other part is sent back to the cold hydrogenation system for reuse. The third gas phase 071 is pressurized by the top tail gas booster 08 to obtain the fourth gas phase 081, and the fourth gas phase 081 is sent to the bottom of the high boiling reactor 12 to participate in the reaction. The temperature of the fourth gas phase 081 is controlled to be 70~90℃, and the pressure is 0.15~0.25Mpa;

[0046] 3) The high boiling chlorosilane product 053 is sent to the high boiling reactor 12 to participate in the reaction after the temperature is controlled at 70-95°C by the feed cooler 10. A filter 11 is set before the high boiling chlorosilane product 053 enters the high boiling reactor 12. The filter 11 removes fine silicon powder and metal chloride in the high boiling chlorosilane product 053, and sends it to the neutralization tank 13 for treatment; the high boiling chlorosilane product 053 and the fourth gas phase 081 undergo a cracking reaction in the high boiling reactor 12 to obtain a fifth gas phase 121 containing light chlorosilane. The reaction temperature is indirectly controlled at 70-100°C by the feed cooler 10, and the reaction pressure is controlled at 0.1-0.25MPa; the fifth gas phase 121 is sent to the distillation tower 05 to separate and recover the light chlorosilane component therein, and the unreacted high boiling chlorosilane product 053 is sent to the high boiling reactor 12 through the bottom of the tower again to continue to participate in the reaction;

[0047] 4) A silicon tetrachloride elution line 122 is added to the top of the high boiling reactor 12. When the conversion rate of the high boiling silane 053 is lower than 75%, 3 to 4 t / h of silicon tetrachloride is used to continuously flush the catalyst from top to bottom for 20 to 40 minutes through the silicon tetrachloride elution line 122 to flush the fine silicon powder off the catalyst surface. The flushed fine silicon powder and silicon tetrachloride are discharged to the flash cooling tank 01 through the residual discharge line at the bottom of the high boiling reactor 12, and finally filtered out through a vacuum drum cake layer, and the silicon tetrachloride used for flushing is recovered.

[0048] The advantages of this method are as follows: ① The same distillation tower is used to separate and purify the slurry clear liquid and high-boiling reaction products at the same time, reducing the cost of equipment investment; ② This process makes full use of the preheating of the distillation tower kettle for cracking reaction, and there is no need to heat the high-boiling chlorosilane for reaction, which reduces the reaction energy consumption, and the reaction temperature can be indirectly controlled by the feed cooler to make the reaction more stable and reduce the generation of by-products; ③ When the catalyst surface is gradually covered with fine silicon powder, the effective contact area between it and the reactant is reduced, resulting in a decrease in mass transfer and heat transfer rate, which in turn leads to a decrease in reaction rate or even failure to react. Through the silicon tetrachloride elution pipeline set at the top of the high-boiling reactor, silicon tetrachloride is used to flush the fine silicon powder on the catalyst surface away from the catalyst surface, so that the effective contact area between the catalyst and the reactant can be restored, thereby improving the reaction rate and extending the service life of the catalyst.

[0049] Beneficial effects of the above scheme:

[0050] (1) The same distillation tower is used to separate and purify the slurry clear liquid and high-boiling reaction products at the same time, reducing the cost of equipment investment.

[0051] (2) The high-boiling substances are extracted from the bottom of the distillation tower and enter the cracking reactor through the bottom cooler. The gaseous chlorosilane obtained by cracking is returned to the distillation tower for separation and recovery, and then returned to the cold hydrogenation system for recycling, thereby improving the utilization rate of silicon elements. The temperature of the cracking reactor is controlled by adjusting the power of the feed cooler to stabilize it within a reasonable range, effectively avoiding the abnormality caused by overheating of the high-boiling reactor or the inability to react due to low temperature. At the same time, the heat of the bottom is fully utilized, and the high-boiling substances can complete the required reaction before or after entering the high-boiling reactor without additional heating, thereby reducing the heating energy consumption compared with the existing technology, thereby saving costs.

[0052] (3) By setting a silicon tetrachloride spray pipeline on the top of the high boiling reactor, the microparticles attached to the catalyst surface can be effectively cleaned and removed, and the residual liquid after cleaning is recovered through the slurry treatment system to recover the chlorosilane therein, thereby extending the service life of the catalyst and improving the chlorosilane recovery rate.

[0053] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0054] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polysilicon cold hydrogenation slag slurry high boiling point recovery system, characterized in that: have: It includes a solid-liquid separation device, a separation and purification device and a high-boiling cracking device; The solid-liquid separation device comprises a flash cooling tank, a vacuum filter, a clear liquid tank and a flash condenser connected by pipelines; The separation and purification device comprises a distillation tower, a tower top water cooler, a tower top deep cooler, a tower top tail gas booster, and a reflux tank connected by pipelines; The high boiling cracking device comprises a feed cooler, a filter and a high boiling reactor connected by pipelines.

2. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 1, characterized in that: The distillation tower is connected to the top water cooler through a gas phase pipeline, the top water cooler is connected to the top deep freezer through a gas phase outlet pipeline, the top deep freezer is connected to the top tail gas booster through a gas phase pipeline, the top tail gas booster is connected to the high boiling cracking device through a gas phase outlet pipeline, and the distillation tower is connected to the high boiling cracking device through a bottom discharge pipeline.

3. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 2, characterized in that: The reflux tank receives liquid materials from the tower top water cooler and the tower top deep cooler through a liquid feed pipe; the reflux tank returns the liquid materials to the distillation tower for reflux through a liquid discharge pipe, and extracts the liquid materials through an extraction pipeline and sends them to the hydrogenation system for recycling.

4. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 3, characterized in that: The distillation tower receives the cracking product of the high-boiling cracking unit through a gas phase feed pipeline.

5. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 4, characterized in that: The feed cooler is connected to the distillation tower via a tower bottom discharge pipeline, and the filter and the high boiling reactor are sequentially connected to the downstream of the feed cooler.

6. The polysilicon cold hydrogenation slag high boiling point recovery system according to claim 5, characterized in that: The high boiling reactor receives gas from the tail gas booster at the top of the tower through a gas phase pipeline, receives high boiling products from the bottom of the distillation tower through a high boiling pipeline, and the gas generated by the reaction is sent to the distillation tower through the gas phase pipeline for separation and purification.

7. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 6, characterized in that: The top of the high boiling reactor is provided with a silicon tetrachloride feeding pipeline, and the bottom is provided with a residual discharge pipeline connected with the feeding port of the flash cooling tank.

8. The polysilicon cold hydrogenation slag slurry high boiling point recovery system according to claim 7, characterized in that: The invention also comprises a neutralization treatment device, which is a neutralization tank connected with a filter.

9. The recovery method of the polysilicon cold hydrogenation slag high boiling point recovery system according to any one of claims 1 to 8, characterized in that: The steps include: 1) Discharge the cold hydrogenated slag slurry into a flash cooling tank for flash evaporation to obtain a first gas phase and a first slurry, control the flash pressure at 0.01-0.1 MPa, the temperature of the first slurry at 30-50°C, and the liquid level at 20-60%; condense the first gas phase through a flash condenser to obtain a first clear liquid, which is sent to a clear liquid tank for buffering, and control the temperature of the first clear liquid at -10--30°C; separate the first slurry into a first solid slag and a second clear liquid through a vacuum drum filter for solid-liquid separation, and send the first solid slag to a neutralization tank through a solid slag discharge pipeline for treatment and then discharge, and send the second clear liquid to a clear liquid tank and mix it with the first clear liquid to obtain a third clear liquid; 2) The third clear liquid is sent to a distillation tower for separation, and a second gas phase containing light component chlorosilane is obtained at the top of the tower, and a high-boiling product of chlorosilane is obtained at the bottom of the tower. The pressure at the top of the tower is controlled to be 0.1-0.2MPa, the temperature is 60-80°C, and the pressure at the bottom of the tower is 0.15-0.25MPa, and the temperature is 80°C-100°C; the second gas phase is condensed by a water cooler at the top of the tower and a deep cooler at the top of the tower to obtain a fourth clear liquid and a third gas phase, and the temperature of the third gas phase is controlled to be -10--30°C and the pressure is 0.08-0.18MPa. A part of the fourth clear liquid is used as a reflux at the top of the distillation tower, and the other part is sent back to the cold hydrogenation system for reuse. The third gas phase is pressurized by a tail gas booster at the top of the tower to obtain a fourth gas phase, and the fourth gas phase is sent to the bottom of the high-boiling reactor to participate in the reaction, and the temperature of the fourth gas phase is controlled to be 70-90°C and the pressure is 0.15-0.25Mpa; 3) The high-boiling chlorosilanes are sent to a high-boiling reactor to participate in the reaction after the temperature is controlled at 70-95° C. by a feed cooler. A filter is set before the high-boiling chlorosilanes enter the high-boiling reactor. The filter removes fine silicon powder and metal chloride in the high-boiling chlorosilanes, and the high-boiling chlorosilanes are sent to a neutralization tank for treatment; the high-boiling chlorosilanes and the fourth gas phase undergo a cracking reaction in the high-boiling reactor to obtain a fifth gas phase containing light-component chlorosilanes, and the reaction temperature is indirectly controlled at 70-100° C. by a feed cooler, and the reaction pressure is controlled at 0.1-0.25 MPa; the fifth gas phase is sent to a distillation tower to separate and recover the light-component chlorosilanes therein, and the unreacted high-boiling chlorosilanes are sent to the high-boiling reactor again through the bottom of the tower to continue to participate in the reaction; 4) A silicon tetrachloride elution pipeline is added to the top of the high boiling reactor. When the conversion rate of high boiling silane is lower than 75%, 3-4 t / h of silicon tetrachloride is used to continuously wash the catalyst from top to bottom for 20-40 minutes through the silicon tetrachloride elution pipeline to wash the fine silicon powder off the catalyst surface. The washed fine silicon powder and silicon tetrachloride are discharged to the flash cooling tank through the residual discharge pipeline at the bottom of the high boiling reactor, and finally filtered out through the vacuum drum cake layer, and the silicon tetrachloride used for washing is recovered.

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