CN219429723U - Waste gas and slag slurry recovery system in polycrystalline silicon production process - Google Patents

Abstract

The application relates to a waste gas, sediment thick liquid recovery system in polycrystalline silicon production process, exhaust emission pipeline links to each other with the exhaust gas inlet of scrubbing tower, the liquid phase export of scrubbing tower and sediment thick liquid emission pipeline all link to each other with the import of flash tank, the light component export of flash tank links to each other with the import of retort, the heavy component export of flash tank links to each other with the import of ground jar, the supernatant export of ground jar links to each other with the import of retort, the blowdown exit linkage of ground jar bottom has drying device, drying device's gaseous phase export links to each other with the import of retort, drying device's solid phase export is the silica mud export. The chlorosilane and the silicon powder in the waste gas and the slag slurry can be recovered, the resource waste is avoided, the recovery rate is improved through multistage recovery, a large amount of cold energy, alkali liquor and lime milk are not required to be consumed, the purchasing expenditure is reduced, the waste gas treatment cost is reduced, and the silicon slurry recovery can bring considerable economic benefit for enterprises additionally, so that the economic benefit in the production of the polysilicon is improved.

Description

Waste gas and slag slurry recovery system in polycrystalline silicon production process

Technical Field

The application relates to the technical field of polysilicon production, in particular to a waste gas and slag slurry recovery system in the polysilicon production process.

Background

In the production process of polysilicon, a large amount of waste gas and slag slurry are generated, wherein the waste gas contains chlorosilane, silicon powder and the like, and the slag slurry mainly comprises about 5% of solid-phase components (silicon powder particles) and about 95% of liquid-phase components (chlorosilane, high-boiling substances and the like), wherein the liquid components of the chlorosilane account for more than 90%.

At present, the waste gas treatment mode in the polysilicon industry is mainly to treat the waste gas by leaching and absorbing with alkali liquor, the method consumes a large amount of alkali liquor and causes waste of chlorosilane and silicon powder, in order to reduce resource waste, polysilicon production enterprises begin to adopt various methods to recycle the waste gas, and at present, the waste gas recovery treatment in the polysilicon production process mainly adopts the following methods: the deep cooling method adopts a low-temperature leaching or condensing method to deeply cool the waste gas, reduces the temperature of the gas to below 20 ℃ below zero, condenses chlorosilane in the waste gas into liquid, and thus recovers part of the effective substance chlorosilane in the waste gas. The method has the defects that a large amount of cold energy is required to be consumed, silicon powder is not recovered, the recovery rate of chlorosilane is low, resource waste is caused, and the waste gas is still required to be treated again by adopting an alkaline solution leaching method after being subjected to deep cooling.

The method for treating the slag slurry in the polycrystalline silicon industry is to adopt drying equipment to heat, evaporate and recycle the chlorosilane in the slag slurry, and discharge the treated waste slag into water for hydrolysis, but the waste slag contains silicon powder and chlorosilane, if the waste slag is directly subjected to hydrolysis treatment, the silicon powder and the chlorosilane are wasted, so that the waste of resources is caused, a large amount of lime milk and water resources are consumed in the hydrolysis treatment process, no economic benefit is generated, a large amount of lime milk purchase cost is required, a large amount of water resources are required to be consumed in the hydrolysis reaction, and the water resources are polluted by metal chloride generated in the reaction process.

Disclosure of Invention

Based on the above, it is necessary to solve the problems of the prior art that a large amount of cold energy, alkali liquor, lime milk and water resources are consumed in the treatment of waste gas and slag slurry, no economic benefit is generated, a large amount of purchasing cost is required, the recovery rate is low, and silicon powder and chlorosilane resources are wasted. The utility model provides a waste gas, sediment thick liquid recovery system in polycrystalline silicon production process can retrieve chlorosilane and silica flour in waste gas and the sediment thick liquid, avoids causing the wasting of resources, and through multistage recovery, has improved the rate of recovery, need not consume a large amount of coldness, alkali lye and lime milk, and the silicon mud is retrieved and can bring considerable economic benefits for the enterprise is extra, avoids not producing any economic benefits and need expend a large amount of purchase expense.

The utility model provides an exhaust gas, sediment thick liquid recovery system in polycrystalline silicon production process, includes sediment thick liquid discharge pipeline, exhaust gas discharge pipeline, scrubbing tower, flash tank, retort and ground jar, exhaust gas discharge pipeline with the exhaust gas inlet of scrubbing tower links to each other, the gaseous phase export of scrubbing tower is the evacuation mouth, the liquid phase export of scrubbing tower with sediment thick liquid discharge pipeline all with the import of flash tank links to each other, the light component export of flash tank with the import of retort links to each other, the light component export of retort links to each other with cold hydrogenation system, the heavy component outlet of retort is high boiling recovery export, the heavy component outlet of flash tank with the import of ground jar links to each other, the supernatant export of ground jar with the import of retort links to each other, the bottom of ground jar has the drain outlet, the drain outlet is connected with drying device, drying device's gaseous phase export with the import of retort links to each other, drying device's solid phase export is the mud export.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the system further comprises a precipitation tank, a liquid phase outlet of the washing tower is connected with an inlet of the precipitation tank, a supernatant outlet of the precipitation tank is connected with an inlet of the flash tank, and a precipitation outlet at the bottom of the precipitation tank is connected with an inlet of the drying device.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the washing tower is provided with a reflux pipeline, one end of the reflux pipeline is connected with the bottom of the washing tower, and the other end of the reflux pipeline is connected with a washing water inlet of the washing tower.

Preferably, in the waste gas and slag slurry recovery system in the polysilicon production process, a flame arrester is installed at a gas phase outlet of the washing tower.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the system further comprises a filter, the slurry discharge pipeline is further connected with an inlet of the filter, a gas-liquid outlet of the filter is connected with an inlet of the distillation tank, and a solid phase outlet of the filter is connected with an inlet of the drying device.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the system further comprises a clean liquid tank and a first cooling device, wherein the light component outlet of the flash tank, the supernatant outlet of the ground tank and the gas phase outlet of the drying device are all connected with the inlet of the first cooling device, the outlet of the first cooling device is connected with the inlet of the clean liquid tank, and the outlet of the clean liquid tank is connected with the inlet of the distillation tank.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the system further comprises a condensate cooling tank, wherein a light component outlet of the distillation tank is connected with an inlet of the condensate cooling tank, and an outlet of the condensate cooling tank is connected with the cold hydrogenation system.

Preferably, in the waste gas and slurry recycling system in the polysilicon production process, the system further comprises a second cooling device, wherein the heavy component outlet of the flash tank is connected with the inlet of the second cooling device, and the outlet of the second cooling device is connected with the inlet of the ground tank.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the distillation tank and the flash tank are both of an outer coil heating structure, and a steam heating outlet of the distillation tank is connected with a steam heating inlet of the flash tank.

Preferably, in the waste gas and slurry recovery system in the polysilicon production process, the drying device is an outer coil heating structure, and the steam heating outlet of the distillation tank is also connected with the steam heating inlet of the drying device.

The technical scheme that this application adopted can reach following beneficial effect:

in this application embodiment disclosed in waste gas, sediment thick liquid recovery system in polycrystalline silicon production process, at first drip washing waste gas, with silica flour and chlorosilane drip washing in the waste gas to wash in the mother liquor, other waste gas evacuation in the waste gas, then let in the flash tank with washing mother liquor and sediment thick liquid, let in the flash tank the light component that flash tank flash distillation obtained into the still pot, the still pot evaporates the chlorosilane in the liquid light component, and let in the cold hydrogenation system conversion turns into trichlorosilane, and then realize the recycle of chlorosilane, avoid the chlorosilane extravagant, and play the effect of rectification purification through the still pot, so that the high-boiling substance that will not evaporate of still pot is let in high-boiling recovery system through high-boiling recovery export, with high-boiling substance schizolysis conversion recovery, avoid the wasting of resources, let in the floor pot through the heavy component that flash tank obtains into the floor pot and keep still the sediment, let in the supernatant in the still pot, the lower floor's cloudy thing after layering is let in drying device through the drain export and is turned into trichlorosilane, and realize the recovery of chlorosilane, wherein, the recovery of the gaseous state mud is carried out to the silicon through the dry silicon, the silicon is realized to retrieve the silica flour.

Drawings

Fig. 1 is a schematic diagram of an exhaust gas and slurry recovery system in a polysilicon production process according to an embodiment of the present application.

Wherein: slurry discharge line 110, off-gas discharge line 120, scrubber 210, return line 211, flame arrestor 212, flash tank 220, distillation tank 230, ground tank 240, settling tank 250, drying unit 310, filter 320, clear liquid tank 330, first cooling unit 340, condensate cooling tank 350, and second cooling unit 360.

Description of the embodiments

In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "top," "bottom," "top," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, an embodiment of the present application discloses a waste gas and slurry recovery system in a polysilicon production process, which includes a slurry discharge pipe 110, a waste gas discharge pipe 120, a scrubber 210, a flash tank 220, a distillation tank 230 and a ground tank 240, wherein:

the exhaust gas discharge pipeline 120 is connected with an exhaust gas inlet of the washing tower 210, so that exhaust gas generated in the production process of polysilicon is introduced into the washing tower 210 through the exhaust gas discharge pipeline 120 to be leached, silicon powder and chlorosilane in the exhaust gas are leached into washing mother liquor, other exhaust gases (hydrogen, nitrogen and the like) in the exhaust gas are discharged through a gas phase outlet of the washing tower 210, the gas phase outlet of the washing tower 210 is an emptying port, and other exhaust gases in the exhaust gas are emptied after hydrogen in the exhaust gas is ignited and combusted during emptying, so that the environment is prevented from being polluted by the hydrogen. The liquid phase outlet of the washing tower 210 and the slag slurry discharge pipeline 110 are connected with the inlet of the flash tank 220 so as to introduce the washing mother liquor and slag slurry in the production process of polysilicon into the flash tank 220, so that silicon powder and chlorosilane in waste gas are introduced into the flash tank 220 and recycled in the subsequent process flow, other waste gases in the waste gas are emptied, the waste gas treatment is realized, a large amount of cold energy and alkali liquor are not consumed in the process, purchasing expenditure is reduced, waste gas treatment cost is reduced, and the silicon powder and chlorosilane are recycled, so that the resource waste is avoided.

When the flash tank 220 works, the temperature is about 70 ℃ to 80 ℃, so that the light components (chlorosilane) in the washing mother liquor and the slag slurry are flashed into gas, and part of high-boiling substances also enter the light components during the flash evaporation, and heavy components (silicon powder, polymers, high-boiling substances and the like) in the washing mother liquor and the slag slurry exist at the bottom of the flash tank 220 in the form of a solid-liquid mixture.

The light component outlet of the flash tank 220 is connected with the inlet of the distillation tank 230, so that the light component obtained by flash evaporation of the washing mother liquor and the slag slurry through the flash tank 220 is introduced into the distillation tank 230, the light component is gradually cooled into a liquid state in the pipeline in the process of being introduced into the distillation tank 230 through the pipeline, the light component entering the distillation tank 230 is in the liquid state, the temperature is about 120 ℃ when the distillation tank 230 works, so that chlorosilane in the liquid light component is distilled out, and the distillation tank 230 has the effect of rectification and purification. The light component outlet of the distillation tank 230 is connected with the cold hydrogenation system, so that chlorosilane distilled out of the distillation tank 230 is introduced into the cold hydrogenation system to be converted into trichlorosilane, the trichlorosilane is introduced into the reduction furnace to be produced into polysilicon, further, recycling of chlorosilane in washing mother liquor and slag slurry is realized, the chlorosilane is avoided being wasted, meanwhile, the distillation tank 230 has the effect of rectifying and purifying, so that the purity of the recycled chlorosilane is higher, the effect that the effect of introducing part of recycled chlorosilane into the cold hydrogenation system to react is avoided, the efficiency of the cold hydrogenation system is influenced due to lower purity and lower yield, unreacted chlorosilane returns into the slag slurry, the load of the cold hydrogenation slag slurry treatment system is larger, the unreacted chlorosilane is caused to circulate in the system but not be recycled, and the meaning of setting the cold hydrogenation slag slurry treatment system is poor.

Most of the non-steamed parts of the distillation tank 230 are high-boiling residues, and the heavy component outlet of the distillation tank 230 is a high-boiling recovery outlet, so that the non-steamed high-boiling residues of the distillation tank 230 are introduced into a high-boiling recovery system through the high-boiling recovery outlet, and the high-boiling residues are cracked, converted and recovered, so that resource waste is avoided.

The heavy component outlet of the flash tank 220 is connected with the inlet of the ground tank 240, so that heavy components obtained by passing the washing mother liquor and the slag slurry through the flash tank 220 are introduced into the ground tank 240 from the bottom of the flash tank 220, the heavy components are gradually cooled to normal temperature in a pipeline in the process of being introduced into the ground tank 240 through the pipeline, the temperature of the heavy components entering the ground tank 240 is normal temperature, the solid-liquid mixture of the heavy components is kept stand and precipitated in the ground tank 240, layering is realized, the upper layer is supernatant, the main component is chlorosilane, the lower layer is turbid, and the main components are silicon powder, polymers, high-boiling substances and the like. The supernatant outlet of the ground tank 240 is connected with the inlet of the distillation tank 230, so that the supernatant in the ground tank 240 is introduced into the distillation tank 230, the supernatant is mixed with the light component liquid obtained by flash evaporation of the flash tank 220, the chlorosilane is distilled out through the distillation tank 230, and the distillation tank 230 has the effect of rectification and purification, so that the purity of the recovered chlorosilane is higher.

The bottom of the ground tank 240 is provided with a drain outlet, the lower turbid material after standing and layering of the ground tank 240 is discharged through the drain outlet, the drain outlet is connected with a drying device 310, so that the lower turbid material is introduced into the drying device 310 for drying, the drying device 310 is mainly heated by steam for drying, a gas phase outlet of the drying device 310 is connected with an inlet of the distillation tank 230, liquid substances (mainly chlorosilane) in the lower turbid material are all changed into gas in the drying process, then part of gaseous chlorosilane is introduced into the distillation tank 230, and similarly, part of gaseous chlorosilane is gradually cooled into liquid in a pipeline in the process of being introduced into the distillation tank 230 for rectification and purification.

In the drying process, solid matters (mainly silicon powder, polymers, high-boiling matters and the like) in the turbid matters at the lower layer are all changed into solid matters, the silicon mud is obtained after drying, a solid-phase outlet of the drying device 310 is a silicon mud outlet, and the dried silicon mud is discharged through the silicon mud outlet.

In the waste gas and slag slurry recovery system in the polycrystalline silicon production process disclosed by the embodiment of the application, firstly, leaching waste gas is carried out, so that silicon powder and chlorosilane in the waste gas are leached into washing mother liquor, other waste gas in the waste gas is emptied, then the washing mother liquor and slag slurry are introduced into a flash tank 220, light components obtained by flash evaporation of the flash tank 220 are introduced into a distillation tank 230, the distillation tank 230 evaporates chlorosilane in the liquid light components and is introduced into a cold hydrogenation system to convert the liquid light components into trichlorosilane, further, recycling of the chlorosilane is realized, waste of the chlorosilane is avoided, and the effect of rectification and purification is achieved through the distillation tank 230, so that the recovered chlorosilane has higher purity, high-boiling substances which are not evaporated out of the distillation tank 230 are introduced into the high-boiling recovery system through a high-boiling recovery outlet, the high-boiling substances are cracked and converted to be recovered, resource waste is avoided, heavy components obtained through the flash tank 220 are introduced into a ground tank 240 to be placed in a still precipitation tank, supernatant in the ground tank 240 is introduced into the distillation tank 230, the chlorosilane is recovered, the turbid ground tank 240 is layered and then is converted into trichlorosilane, the recycling of the trichlorosilane is realized, the silicon is discharged into the silicon through a drying device through the distillation tank 310, and the silicon powder is recovered through the drying device, and the waste of the silicon is avoided.

Therefore, the waste gas and slag slurry recovery system in the polysilicon production process disclosed by the embodiment of the application can recover the chlorosilane and silicon powder in the waste gas and slag slurry, so that resource waste is avoided, and the chlorosilane is fully and effectively recovered through multistage recovery, the silicon powder is completely recovered through the silicon slurry, the recovery rate is improved, a large amount of cold energy, alkali liquor and lime milk are not required to be consumed, and the silicon slurry recovery can additionally bring considerable economic benefit to enterprises, so that the economic benefit is avoided, a large amount of purchasing cost is required to be paid, purchasing cost is reduced, waste gas treatment cost is reduced, the related problems in the prior art are solved, the treatment recovery of the waste gas and slag slurry is realized, the economic benefit in the polysilicon production is improved, and the resource-saving polysilicon production mode is constructed.

Further, the system for recycling waste gas and slurry in the production process of polysilicon disclosed in the application can further comprise a precipitation tank 250, wherein the liquid phase outlet of the washing tower 210 is connected with the inlet of the precipitation tank 250, so that washing mother liquor is introduced into the precipitation tank 250 for standing, precipitating and layering, the upper layer is supernatant, the lower layer is a precipitated silica mud layer containing a large amount of silicon powder, the supernatant outlet of the precipitation tank 250 and the slurry discharge pipeline 110 are both connected with the inlet of the flash tank 220, so that the supernatant is introduced into the flash tank 220 for recycling chlorosilane, and the precipitation outlet at the bottom of the precipitation tank 250 is connected with the inlet of the drying device 310, so that the precipitated silica mud layer is introduced into the drying device 310 for drying, and the silica mud is recycled. According to the technical scheme, the precipitation tank 250 is arranged, and the leaching mother liquor is kept stand for precipitation, so that all leaching mother liquor is prevented from being fully introduced into the flash tank 220 and the subsequent process flow, and the loads of the flash tank 220 and the subsequent process flow are reduced.

Preferably, the washing tower 210 has a reflux pipe 211, one end of the reflux pipe 211 is connected to the bottom of the washing tower 210, and the other end is connected to a washing water inlet of the washing tower 210, and the washing mother liquor at the bottom of the washing tower 210 is pumped to the washing water inlet through the reflux pipe 211, and then the waste gas is leached again through the washing water inlet, so that the reflux of the washing mother liquor is realized, and the consumption of washing water is effectively reduced.

Preferably, the gas phase outlet of the scrubber 210 is provided with the flame arrester 212, other waste gases (hydrogen, nitrogen, etc.) in the waste gases are discharged through the gas phase outlet of the scrubber 210, and as a small amount of silicon powder may exist in the waste gases, the silicon powder combusts and ignites spontaneously, the flame arrester 212 can prevent the silicon powder combusts and ignites to cause the fire condition of the whole system, safety accidents occur, and the safety of the whole system is improved.

For the slurry with the solid content of more than 5% by adopting the disclosed system, for the slurry with the solid content of less than 5%, because the slurry has fewer solid particles, that is, less silicon powder, most of the slurry is recyclable chlorosilane, if the disclosed system is adopted, the slurry treatment process with the solid content of less than 5% is complicated, and the treatment cost is high, therefore, in an alternative embodiment, the waste gas and slurry recycling system in the polysilicon production process disclosed in the application can further comprise a filter 320, the slurry discharge pipeline 110 is further connected with the inlet of the filter 320, so as to introduce the slurry with the solid content of less than 5% into the filter 320, in the filter 320, the slurry realizes solid-liquid separation, the separated slurry is a gas-liquid mixture and a solid-liquid mud-like mixture, the gas-liquid outlet of the filter 320 is connected with the inlet of the distillation tank 230, so that the gas-liquid mixture (mainly chlorosilane) separated in the filter 320 is introduced into the distillation tank 230, the chlorosilane is discharged from the distillation tank 230, and the distillation tank 230 is distilled to realize the recycling effect of the purified silane. The solid phase outlet of the filter 320 is connected with the inlet of the drying device 310, so that the solid-liquid mud-like mixture separated in the filter 320 is introduced into the drying device 310 for drying, the gaseous chlorosilane obtained by drying is introduced into the distillation tank 230, the chlorosilane in the gaseous chlorosilane is recovered, the dried silicon mud is discharged through the silicon mud outlet, and the silicon mud is recovered, so that the recovery of silicon powder is realized, and the waste of silicon powder is avoided.

Above adopts different processing systems to the sediment thick liquid of solid content difference to convenient high-efficient processing sediment thick liquid avoids redundant processing, avoids processing cost higher.

As described above, the light components obtained by flash evaporation of the slurry in the flash evaporation tank 220 are gradually cooled in the pipeline to be in liquid state, so that the light components entering the distillation tank 230 are in liquid state, if the gaseous substances are directly introduced into the distillation tank 230, the gaseous substances are directly discharged from the light component outlet of the distillation tank 230, so that the distillation tank 230 does not carry out rectification purification on the part of the gaseous substances, and the meaning of the distillation tank 230 is not great, so that the substances to be rectified and purified introduced into the distillation tank 230 need to be in liquid state, and in order to ensure that the substances introduced into the distillation tank 230 are in liquid state, in an alternative embodiment, the waste gas and slurry recovery system in the polysilicon production process disclosed in the application further comprises a clean liquid tank 330, wherein the light component outlet of the flash tank 220, the supernatant outlet of the ground tank 240 and the gas phase outlet of the drying device 310 are all connected with the inlet of the clean liquid tank 330, and the outlet of the clean liquid tank 330 is connected with the inlet of the distillation tank 230. The front end of the inlet of the distillation tank 230 is provided with the clear liquid tank 330 so that gaseous substances are gradually cooled into liquid state in a pipeline, and then are introduced into the clear liquid tank 330 for buffering, even if part of the gaseous substances are not cooled into liquid state, the uncooled gaseous substances are gradually cooled into liquid state in the clear liquid tank 330 due to the existence of the clear liquid tank 330, and then the liquid substances are introduced into the distillation tank 230 for rectification and purification, so that the substances introduced into the distillation tank 230 are ensured to be liquid state, and the phenomenon that the distillation tank 230 does not rectify and purify the gaseous substances due to the fact that the gaseous substances are directly introduced into the distillation tank 230 is avoided, and the recovered chlorosilane is prevented from being lower in purity.

Further, the waste gas and slurry recovery system in the polysilicon production process disclosed in the application may further include a first cooling device 340, wherein the light component outlet of the flash tank 220, the supernatant outlet of the ground tank 240 and the gas phase outlet of the drying device 310 are all connected with the inlet of the first cooling device 340, the outlet of the first cooling device 340 is connected with the inlet of the supernatant tank 330, and substances introduced into the distillation tank 230 are firstly cooled by adding the first cooling device 340 to be guaranteed to be cooled to be liquid, then introduced into the supernatant tank 330 for buffering, and then the liquid substances are introduced into the distillation tank 230 for rectification and purification, so that the substances introduced into the distillation tank 230 are further guaranteed to be liquid, and the reliability of the cold hydrogenated slurry treatment system is improved.

Preferably, the system for recycling waste gas and slurry in the polysilicon production process disclosed in the application may further include a condensate cooling tank 350, wherein the light component outlet of the distillation tank 230 is connected to the inlet of the condensate cooling tank 350, the outlet of the condensate cooling tank 350 is connected to the cold hydrogenation system, and the condensate cooling tank 350 is used for cooling and buffering so that chlorosilane introduced into the cold hydrogenation system is in a liquid state, and chlorosilane can be continuously introduced into the cold hydrogenation system through the condensate cooling tank 350.

As described above, heavy components obtained by passing slurry through the flash tank 220 are introduced into the ground tank 240 from the bottom of the flash tank 220, and because the temperature of the heavy components obtained by the flash tank 220 is relatively high in the flash tank 220, if heat is introduced into the ground tank 240 by directly introducing the heavy components into the ground tank 240, part of liquid substances in the ground tank 240 are vaporized, resulting in poor settling effect of the ground tank 240, and the settling time period of settling is prolonged.

As described above, when the flash tank 220 is operated at a temperature of about 70 ℃ to 80 ℃, and when the distillation tank 230 is operated at a temperature of about 120 ℃, the flash tank 220 and the distillation tank 230 are heated by steam, so that the flash tank 220 needs to be heated by steam of about 90 ℃, the distillation tank 230 needs to be heated by steam of about 130 ℃, preferably, the distillation tank 230 and the flash tank 220 are both in an outer coil heating structure, and the steam heating outlet of the distillation tank 230 is connected with the steam heating inlet of the flash tank 220, so that the steam after heating the distillation tank 230 is used for heating the flash tank 220, thereby realizing the cascade utilization of heat in the steam, reducing the consumption of the steam and avoiding the waste of heat in the steam.

Further, the drying device 310 may also be an external coil heating structure, and the steam heating outlet of the distillation tank 230 is further connected with the steam heating inlet of the drying device 310, so that the steam after heating the distillation tank 230 is used for providing heat required for drying for the drying device 310, so that the steam can be utilized in two stages, the heat in the steam can be fully utilized, the consumption of the steam can be reduced, and the waste of the heat in the steam can be avoided.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the claims. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims (10)

1. Waste gas, sediment thick liquid recovery system in polycrystalline silicon production process, characterized by, including sediment thick liquid discharge pipeline (110), waste gas discharge pipeline (120), scrubbing tower (210), flash distillation tank (220), distillation tank (230) and ground jar (240), waste gas discharge pipeline (120) with the waste gas import of scrubbing tower (210) links to each other, the gas phase export of scrubbing tower (210) is the evacuation mouth, the liquid phase export of scrubbing tower (210) with sediment thick liquid discharge pipeline (110) all with the import of flash distillation tank (220) links to each other, the light fraction export of flash distillation tank (220) with the import of distillation tank (230) links to each other, the light fraction export of distillation tank (230) links to each other with cold hydrogenation system, the heavy fraction export of distillation tank (230) is high-boiling recovery export, the heavy fraction export of distillation tank (220) with the import of ground jar (240) links to each other, the supernatant export of ground jar (240) links to each other with the import of distillation tank (230), the bottom of ground jar (240) has the export of drying device (310) has, drying device (310) has the import of drying device.

2. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, further comprising a settling tank (250), wherein a liquid phase outlet of the washing tower (210) is connected to an inlet of the settling tank (250), a supernatant outlet of the settling tank (250) is connected to an inlet of the flash tank (220), and a settling outlet at a bottom of the settling tank (250) is connected to an inlet of the drying device (310).

3. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, wherein the washing tower (210) is provided with a return pipe (211), one end of the return pipe (211) is connected with the bottom of the washing tower (210), and the other end is connected with a washing water inlet of the washing tower (210).

4. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, wherein a flame arrester (212) is installed at the gas phase outlet of the scrubber (210).

5. The system for recycling waste gas and slurry in a polysilicon production process according to claim 1, further comprising a filter (320), wherein the slurry discharge pipe (110) is further connected to an inlet of the filter (320), a gas-liquid outlet of the filter (320) is connected to an inlet of the distillation tank (230), and a solid phase outlet of the filter (320) is connected to an inlet of the drying device (310).

6. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, further comprising a clean liquid tank (330) and a first cooling device (340), wherein the light component outlet of the flash tank (220), the supernatant outlet of the ground tank (240) and the gas phase outlet of the drying device (310) are all connected with the inlet of the first cooling device (340), the outlet of the first cooling device (340) is connected with the inlet of the clean liquid tank (330), and the outlet of the clean liquid tank (330) is connected with the inlet of the distillation tank (230).

7. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, further comprising a condensate cooling tank (350), wherein the light component outlet of the distillation tank (230) is connected to the inlet of the condensate cooling tank (350), and the outlet of the condensate cooling tank (350) is connected to the cold hydrogenation system.

8. The system for recycling waste gas and slurry in the production process of polysilicon according to claim 1, further comprising a second cooling device (360), wherein the heavy component outlet of the flash tank (220) is connected to the inlet of the second cooling device (360), and the outlet of the second cooling device (360) is connected to the inlet of the ground tank (240).

9. The system for recycling waste gas and slurry in a polysilicon production process according to claim 1, wherein the distillation tank (230) and the flash tank (220) are both of an external coil heating structure, and a steam heating outlet of the distillation tank (230) is connected with a steam heating inlet of the flash tank (220).

10. The system for recovering waste gas and slurry in a polysilicon production process according to claim 9, wherein the drying device (310) is an external coil heating structure, and the steam heating outlet of the distillation tank (230) is further connected to the steam heating inlet of the drying device (310).