Treatment system for slag slurry in trichlorosilane production process

Abstract

The utility model provides a treatment system for slag slurry in a trichlorosilane production process. The treatment system comprises an evaporation unit, a chlorosilane recovery unit, a hydrolysis unit and a hydrolysis tank gas treatment unit, the evaporation unit comprises a slurry tank and a cylindrical cone dryer, and a slurry pump is arranged on a slurry pipeline; the chlorosilane recovery unit comprises a heat exchanger and a chlorosilane storage tank, and a liquid outlet of the heat exchanger is communicated with the chlorosilane storage tank; the hydrolysis unit comprises a screw pump, a hydrolysis tank, a rectification high-boiling pipeline and a calcium oxide adding groove, the inlet end of the screw pump is connected with a bottom outlet of the cylindrical cone dryer, the outlet end of the screw pump is connected with an upper feed port of the hydrolysis tank, the outlet end of the rectification high-boiling pipeline is connected with a feed port of the hydrolysis tank, and the calcium oxide adding groove is communicated with the top of the hydrolysis tank; and the hydrolysis tank gas treatment unit is connected with a top gas outlet of the hydrolysis tank. According to the invention, efficient recovery of chlorosilane in the slag slurry generated in the production process of trichlorosilane is realized, and pollution of hydrogen chloride to the environment in the slag slurry treatment process is avoided.

Description

Technical Field

[0001] This application relates to the technical field of polysilicon production, and particularly to a treatment system for slurry in the production process of trichlorosilane. Background Technique

[0002] As an important chemical raw material, trichlorosilane has a wide range of applications and plays an important role in fields such as organic synthesis, surface treatment, photovoltaic industry, pesticide manufacturing, and pharmaceutical field. In the synthesis of trichlorosilane, dry silicon powder reacts with dry hydrogen chloride gas in a chlorination boiling furnace at 340°C. The resulting crude trichlorosilane is subjected to wet dust removal, condensation, multi-stage rectification, and then condensation again to obtain trichlorosilane finished product.

[0003] During the wet dust removal process of crude trichlorosilane, a liquid-solid mixture gradually deposits at the bottom of the washing tower. At the same time, high-boiling substances are obtained at the bottom of the rectification tower (primary rectification) of multi-stage rectification, jointly forming slurry. The solids in the slurry are mainly silicon powder particles and entrained metal chloride impurities, and the main components of the liquid are chlorosilane and high-boiling silicone oil. Among the main components of the slurry, trichlorosilane, silicon tetrachloride, and hexachlorodisilane are widely used raw materials in engineering and have great utilization value.

[0004] However, the current treatment method for slurry is to neutralize a large amount of chlorosilane in the slurry through alkali hydrolysis. This not only causes a great waste of resources, but also increases the complexity of subsequent treatment processes, and the hydrogen chloride acid gas generated during the hydrolysis process pollutes the environment. Utility Model Content

[0005] This application provides a treatment system for slurry in the production process of trichlorosilane to solve the above problems mentioned in the background technique.

[0006] This application provides a treatment system for slurry in the production process of trichlorosilane, including: an evaporation unit, a chlorosilane recovery unit, a hydrolysis unit, and a hydrolysis tank gas treatment unit;

[0007] The evaporation unit includes a slurry pool and a cylinder-cone dryer connected to the slurry pool through a slurry pipeline, and a slurry pump is arranged on the slurry pipeline;

[0008] The chlorosilane recovery unit includes a heat exchanger and a chlorosilane storage tank. The air inlet of the heat exchanger is connected to the top air outlet of the cylinder-cone dryer through a first negative pressure fan, and the liquid outlet of the heat exchanger is connected to the chlorosilane storage tank;

[0009] The hydrolysis unit includes a screw pump, a hydrolysis tank, a rectification high-boiling pipeline, and a calcium oxide addition tank. The inlet end of the screw pump is connected to the bottom outlet of the cylinder-cone dryer, the outlet end of the screw pump is connected to the upper feed port of the hydrolysis tank, the outlet end of the rectification high-boiling pipeline is connected to the upper feed port of the hydrolysis tank, the calcium oxide addition tank communicates with the top of the hydrolysis tank, and the hydrolysis tank gas treatment unit is connected to the top gas outlet of the hydrolysis tank.

[0010] Optionally, the bottom outlet of the hydrolysis tank is connected to a filter press, and a solid-phase recovery tank is connected to the solid-phase outlet of the filter press.

[0011] Optionally, the cylinder-cone dryer includes an upper cylinder, a lower cone, and a stirring unit. The upper cylinder and the lower cone are connected by a flange. An upper jacket is provided outside the upper cylinder, a lower jacket is provided outside the lower cone, and the stirring unit is arranged in the drying cavity formed by the upper cylinder and the lower cone.

[0012] Optionally, the stirring unit includes a motor, a main gear, a driven gear, a stirring shaft, a rotary joint, a support housing, and a plurality of support pipes;

[0013] The motor is fixed to the top of the cylinder-cone dryer by bolts. The main gear is fixedly sleeved on the output shaft of the motor. The main gear is meshed and connected with the driven gear. The driven gear is fixedly sleeved on the stirring shaft. The inlet end of the rotary joint is connected to the heat medium pipeline, and the outlet end of the rotary joint is connected to one end of the stirring shaft close to the driven gear. The other end of the stirring shaft vertically extends into the cylinder-cone dryer, and a spiral stirring paddle is arranged outside the stirring shaft;

[0014] The lower end of the stirring shaft extends into the support housing. One ends of the plurality of support pipes communicate with the support housing, and the other ends of the plurality of support pipes communicate with the lower jacket. The connection between the stirring shaft and the support housing is sealed by a bearing.

[0015] Optionally, the hydrolysis tank gas treatment unit includes a first scrubbing tower and an alkali solution tank. A second negative pressure fan is connected between the lower inlet of the first scrubbing tower and the top gas outlet of the hydrolysis tank. The alkali solution tank is connected to the upper part of the first scrubbing tower through a first spray pipe, and a first alkali solution spray pump is arranged on the first spray pipe.

[0016] Optionally, the hydrolysis tank gas treatment unit further includes a second scrubbing tower, a second spray pipe, and a second alkali solution spray pump. The lower inlet of the second scrubbing tower is connected to the top gas outlet of the first scrubbing tower. The second spray pipe is connected between the second scrubbing tower and the alkali solution tank, and the second alkali solution spray pump is arranged on the second spray pipe.

[0017] Optionally, pH meters are arranged in the bottom of both the first scrubbing tower and the second scrubbing tower. A first circulation pipeline is connected between the bottom of the first scrubbing tower and the first spray pipe, and a second circulation pipeline is connected between the bottom of the second scrubbing tower and the second spray pipe.

[0018] Optionally, a vibrator is provided on the outer side of the lower cone.

[0019] The slurry treatment system for trichlorosilane production provided by this application realizes the efficient recovery of chlorosilane in the slurry generated during the trichlorosilane production process. Compared with the prior art, it has the following beneficial effects:

[0020] (1) By heating and raising the temperature of the slurry in the cylinder-cone dryer, trichlorosilane and tetrachlorosilane are evaporated into gases, condensed in the heat exchanger and then recycled. The output of trichlorosilane is increased, the waste of trichlorosilane and tetrachlorosilane is avoided, and the enterprise achieves the effect of increased production. At the same time, the remaining solid residue in the cylinder-cone dryer is hydrolyzed by adding calcium oxide in the hydrolysis tank to generate silicon dioxide and calcium chloride. At the same time, the hydrogen chloride gas generated during the hydrolysis process is introduced into the gas treatment unit of the hydrolysis tank for absorption treatment and then discharged, greatly reducing the waste gas emissions and avoiding the corrosion of substances in the surrounding environment caused by the direct discharge of hydrogen chloride gas, which has good environmental benefits. And when hydrolyzing, the high-boiling substances of the last-stage rectification column are introduced into the hydrolysis tank for slurry preparation, improving the efficiency of the hydrolysis reaction. Compared with adding water for slurry preparation, it not only saves costs, but also converts the polysilanes in the high-boiling substances into silicon dioxide and calcium chloride and recycles them, reducing waste emissions. At the same time, by resourceizing the high-boiling substances through hydrolysis, the waste treatment load of the factory is also greatly reduced. Compared with directly hydrolyzing the slurry, the hydrolysis amount of the slurry is reduced, the usage amount of calcium oxide is reduced, and at the same time, the recovery rates of trichlorosilane and tetrachlorosilane are increased.

[0021] (2) The upper end of the stirring shaft is connected to the heat medium pipeline through a rotary joint. The lower end of the stirring shaft extends into the support shell, and the lower end of the stirring shaft is open. The heat medium enters the stirring shaft through the heat medium pipeline via the rotary joint, so that while the stirring shaft stirs the slurry, it also heats the slurry. The heat medium flows from top to bottom in the stirring shaft and then flows into the support shell. The heat medium in the support shell flows into the lower jacket through multiple support pipes and is discharged. The stirring shaft cooperates with the upper jacket and the lower jacket to heat the slurry simultaneously inside and outside, improving the heating efficiency of the slurry, thereby improving the evaporation efficiency of trichlorosilane and tetrachlorosilane, and at the same time greatly reducing the time used in the slurry evaporation process and improving the slurry treatment efficiency. The connection between the stirring shaft and the support shell is sealed by a bearing to prevent the slurry from entering the support shell.

[0022] (3) For the slurry treatment system provided by this application, the usage amount of alkali liquor is greatly reduced during the treatment process, and the amounts of waste liquid and solid waste are also reduced. Moreover, the structure is simple and it is convenient for large-scale promotion in the industry. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic structural diagram of a slurry treatment system in the production process of trichlorosilane provided by an embodiment of the present application;

[0025] Figure 2 It is a schematic structural diagram of a cylinder-cone dryer provided by an embodiment of the present application;

[0026] Figure 3 It is a schematic structural diagram of a slurry treatment system in the production process of trichlorosilane provided by another embodiment of the present application;

[0027] Explanation of reference numerals:

[0028] 1: slurry pond, 2: cylinder-cone dryer, 110: slurry pipeline, 120: slurry pump, 201: flange, 202: drying chamber, 210: upper cylinder, 211: upper jacket, 220: lower cone, 221: lower jacket, 231: motor, 232: main gear, 233: driven gear, 234: stirring shaft, 235: rotary joint, 236: support housing, 237: support pipe, 238: bearing, 250: vibrator, 310: heat exchanger, 320: chlorosilane storage tank, 330: first negative pressure fan, 410: screw pump, 420: hydrolysis tank, 430: rectification high-boiling pipeline, 431: high-boiling substance valve, 440: calcium oxide addition tank, 450: filter press, 460: solid-phase recovery tank, 510: first washing tower, 520: lye tank, 530: second negative pressure fan, 540: first spray pipe, 541: first lye valve, 550: first lye spray pump, 560: first circulation pipeline, 561: first valve, 610: second washing tower, 620: second spray pipe, 621: second lye valve, 630: second lye spray pump, 640: pH meter, 650: second circulation pipeline, 651: second valve, 2340: spiral stirring paddle. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following clearly and completely describes the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts also belong to the scope of protection of the present application.

[0030] As Figure 1 shown, the present application provides a treatment system for slurry in the production process of trichlorosilane, including: an evaporation unit, a chlorosilane recovery unit, a hydrolysis unit, and a hydrolysis tank gas treatment unit;

[0031] The evaporation unit includes a slurry tank 1 and a cylinder-cone dryer 2 connected to the slurry tank 1 through a slurry pipeline 110, and a slurry pump 120 is arranged on the slurry pipeline 110;

[0032] The chlorosilane recovery unit includes a heat exchanger 310 and a chlorosilane storage tank 320. The air inlet of the heat exchanger 310 is communicated with the top outlet of the cylinder-cone dryer 2 through a first negative pressure fan 330, and the liquid outlet of the heat exchanger 310 is communicated with the chlorosilane storage tank 320;

[0033] The hydrolysis unit includes a screw pump 410, a hydrolysis tank 420, a rectification high-boiling pipeline 430, and a calcium oxide addition tank 440. The inlet end of the screw pump 410 is connected to the bottom outlet of the cylinder-cone dryer 2, the outlet end of the screw pump 410 is connected to the upper feed port of the hydrolysis tank 420, the outlet end of the rectification high-boiling pipeline 430 is connected to the upper feed port of the hydrolysis tank 420, the calcium oxide addition tank 440 is communicated with the top of the hydrolysis tank 420, and the hydrolysis tank gas treatment unit is connected to the top outlet of the hydrolysis tank 420. The connections of the screw pump 410, the rectification high-boiling pipeline 430 and the hydrolysis tank 420 can be the same inlet or different inlets.

[0034] Specifically, during the production process of trichlorosilane, it is necessary to purify the crude trichlorosilane. During the wet dust removal process of the crude trichlorosilane, a liquid-solid mixture gradually deposits at the bottom of the washing tower. After wet dust removal, it still needs to enter a multi-stage rectification tower for further purification, and high-boiling substances are obtained at the bottom of the first-stage rectification tower. The liquid-solid mixture from the washing tower and the high-boiling substances from the first-stage rectification tower form slurry. The composition ratio of the slurry is: monosilicon chlorosilane (30-70 wt%) mainly composed of trichlorosilane and tetrachlorosilane, disilicon chlorosilane (10-20 wt%) mainly composed of hexachlorodisilane (Si2Cl6), high-boiling silicone oil (Si3C l8 、Si4Cl 10 , 5-10 wt%), metal chlorides and solids (AlCl3, FeCl3, Si, 10-30 wt%), etc. The main components in the slurry, trichlorosilane and tetrachlorosilane, are widely used raw materials in engineering and have great utilization value. Through the slurry treatment system provided by the present application, the chlorosilane in the slurry is recovered to improve the recovery rate of trichlorosilane and tetrachlorosilane and avoid waste of resources.

[0035] In this application, the evaporation unit is used to heat the slurry, so that silicon tetrachloride and trichlorosilane in the slurry are heated and evaporated into gas state, and then recovered by the chlorosilane recovery unit, which improves the recovery efficiency and recovery amount of chlorosilane. After the slurry is evaporated, the remaining solid residue is transported to the hydrolysis unit for hydrolysis. Hydrogen chloride gas will be generated during the hydrolysis process. The gas in the hydrolysis unit is introduced into the gas treatment unit of the hydrolysis tank to absorb the hydrogen chloride gas and make the hydrolysis gas harmless before discharging, avoiding the pollution of the hydrogen chloride gas to the atmosphere and the corrosion of the surrounding environment, and having good environmental protection benefits.

[0036] The evaporation unit includes a slurry tank 1 and a cylinder-cone dryer 2. A slurry pump 120 is arranged on the slurry pipeline 110. The slurry tank 1 is used to temporarily store the slurry. Powered by the slurry pump 120, the slurry is transported through the slurry pipeline 110 to the cylinder-cone dryer 2. In the cylinder-cone dryer 2, the slurry is heated, and trichlorosilane and silicon tetrachloride are evaporated into gas, and are sucked into the heat exchanger 310 by the first negative pressure fan 330 to be condensed into liquid, and temporarily stored in the chlorosilane storage tank 320 for recycling. Refrigerant, such as chilled water, is introduced into the heat exchanger 310 to exchange heat with the gaseous chlorosilane, so that the gaseous chlorosilane is condensed into liquid for easy recovery. In this way, the output of trichlorosilane is increased, the waste of trichlorosilane and silicon tetrachloride is avoided, and the enterprise achieves the effect of increasing production.

[0037] After the evaporation in the cylinder-cone dryer 2 is completed, the remaining solid residue is transported to the hydrolysis tank 420 by the screw pump 410. At the same time, the high-boiling substances of the last-stage rectification tower are transported to the hydrolysis tank 420 through the rectification high-boiling pipeline 430. The content of trichlorosilane and silicon tetrachloride in the high-boiling substances of the last-stage rectification tower is very small, which dilutes and adjusts the slurry of the solid residue in the hydrolysis tank 420. Then calcium oxide is added to the hydrolysis tank 420 through the calcium oxide addition tank 440 to hydrolyze the residue. The high-polymer chlorosilane in the residue quickly undergoes a hydrolysis reaction to generate silicon dioxide and calcium chloride. At the same time, hydrogen chloride gas will be generated during the hydrolysis process. The gas in the hydrolysis tank 420 is introduced into the gas treatment unit of the hydrolysis tank for absorption treatment and then discharged, avoiding the corrosion of the substances in the surrounding environment caused by the direct discharge of hydrogen chloride gas.

[0038] Through the above solution, the present application realizes the efficient recovery of chlorosilanes in the slurry generated during the production process of trichlorosilane. By heating and raising the temperature of the slurry in a cylindrical-conical dryer, trichlorosilane and silicon tetrachloride are evaporated into gases and condensed into liquids in a heat exchanger, and then recycled. This increases the output of trichlorosilane, avoids the waste of trichlorosilane and silicon tetrachloride, and achieves the effect of increasing production for the enterprise. At the same time, the remaining solid residue in the cylindrical-conical dryer is hydrolyzed by adding calcium oxide in a hydrolysis tank. The polysilanes in the residue rapidly undergo hydrolysis reactions to generate silicon dioxide and calcium chloride. Meanwhile, the hydrogen chloride gas generated during the hydrolysis process is introduced into the gas treatment unit of the hydrolysis tank for absorption treatment and then discharged, greatly reducing the exhaust gas emissions and avoiding the corrosion of substances in the surrounding environment caused by the direct discharge of hydrogen chloride gas, which has good environmental benefits. And when hydrolyzing, the high-boiling components of the last-stage rectification column are introduced into the hydrolysis tank for slurry adjustment, improving the efficiency of the hydrolysis reaction. Compared with adding water for slurry adjustment, it not only saves costs, but also converts the polysilanes in the high-boiling components into silicon dioxide and calcium chloride and recycles them, reducing waste emissions. At the same time, by resourceifying the high-boiling components through hydrolysis, the waste treatment load of the factory is also greatly reduced. Compared with directly hydrolyzing the slurry, the amount of slurry hydrolysis is reduced, the usage amount of calcium oxide is decreased, and the recovery rates of trichlorosilane and silicon tetrachloride are increased.

[0039] As Figure 1 shown, optionally, the bottom outlet of the hydrolysis tank 420 is connected to a filter press 450, and the solid-phase outlet of the filter press 450 is connected to a solid-phase recovery tank 460.

[0040] Specifically, the solid material obtained after hydrolysis in the hydrolysis tank 420 is transported to the filter press 450 for pressure filtration. The obtained solid silicon dioxide and calcium chloride are recovered in the recovery tank 460 and can be added to concrete, building materials, etc. for waste utilization, reducing solid waste emissions. The liquid after pressure filtration by the filter press 450 is transported to a wastewater treatment station for treatment.

[0041] As Figure 2 shown, optionally, the cylindrical-conical dryer 2 includes an upper cylinder 210, a lower cone 220, and a stirring unit. The upper cylinder 210 and the lower cone 220 are connected by a flange 201. An upper jacket 211 is arranged outside the upper cylinder 210, a lower jacket 221 is arranged outside the lower cone 220, and the stirring unit is arranged in the drying chamber 202 formed by the upper cylinder 210 and the lower cone 220.

[0042] Specifically, the cylinder-cone dryer 2 includes an upper cylinder body 210 and a lower cone 220. An outlet is provided at the bottom of the lower cone 220. Such a conical outlet is conducive to the rapid discharging of the dryer. The upper cylinder body 210 and the lower cone 220 are connected by a flange 201, which facilitates the maintenance and repair of the cylinder-cone dryer 2. An upper jacket 211 is provided outside the upper cylinder body 210, and a lower jacket 221 is provided outside the lower cone 220. A heat medium (such as hot water) is introduced into the upper jacket 211 and the lower jacket 221 to heat the slurry in the cylinder-cone dryer 2, which helps the trichlorosilane and silicon tetrachloride to evaporate by heating, and then facilitates recovery. The stirring unit is used to stir the slurry during heating, improve the heating efficiency of the slurry, and then contribute to the efficient recovery of trichlorosilane and silicon tetrachloride.

[0043] As Figure 2 shown, optionally, the stirring unit includes a motor 231, a main gear 232, a driven gear 233, a stirring shaft 234, a rotary joint 235, a support housing 236 and a plurality of support pipes 237;

[0044] The motor 231 is fixed to the top of the cylinder-cone dryer 2 by bolts. The main gear 232 is fixedly sleeved on the output shaft of the motor 231. The main gear 232 is meshed with the driven gear 233. The driven gear 233 is fixedly sleeved on the stirring shaft 234. The inlet end of the rotary joint 235 is connected to the heat medium pipeline, and the outlet end of the rotary joint 235 is connected to one end of the stirring shaft 234 close to the driven gear 233. The other end of the stirring shaft 234 vertically extends into the cylinder-cone dryer 2, and a spiral stirring paddle 2340 is arranged outside the stirring shaft 234;

[0045] The lower end of the stirring shaft 234 extends into the support housing 236. One ends of the plurality of support pipes 237 are communicated with the support housing 236, and the other ends of the plurality of support pipes 237 are communicated with the lower jacket 221. The connection between the stirring shaft 234 and the support housing 236 is hermetically connected through a bearing 238.

[0046] Specifically, the stirring unit includes a motor 231, a main gear 232, a driven gear 233, a stirring shaft 234, a rotary joint 235, a support housing 236 and a plurality of support pipes 237. The motor 231 is used to provide power and drive the main gear 232 to rotate through the output shaft. The main gear 232 drives the driven gear 233 meshed with it to rotate, and the driven gear 233 is fixedly sleeved on the stirring shaft 234, so that the stirring shaft 234 rotates with the rotation of the driven gear 233. Furthermore, the spiral stirring paddle 2340 outside the stirring shaft 234 stirs the slurry, improves the heating efficiency of the slurry, and then improves the evaporation efficiency of trichlorosilane and silicon tetrachloride.

[0047] The support housing 236 is located at the lower part inside the cylinder-cone dryer 2. A plurality of support pipes 237 play a role in supporting and fixing the support housing 236. At the same time, the upper end of the stirring shaft 234 is connected to the heat medium pipeline through a rotary joint 235. The lower end of the stirring shaft 234 extends into the support housing 236, and the lower end of the stirring shaft 234 is in an open shape. The heat medium enters the stirring shaft 234 through the heat medium pipeline via the rotary joint 235. While the stirring shaft 234 stirs the slurry, it also heats the slurry, and cooperates with the upper jacket 211 and the lower jacket 221 to heat the slurry both inside and outside simultaneously, improving the heating efficiency of the slurry, thereby increasing the evaporation efficiency of trichlorosilane and tetrachlorosilane, greatly reducing the time used in the slurry evaporation process, and improving the slurry treatment efficiency. The connection between the stirring shaft 234 and the support housing 236 is hermetically connected through a bearing 238 to prevent the slurry from entering the support housing 236.

[0048] The heat medium flows from top to bottom in the stirring shaft 234 into the support housing 236. Since a plurality of support pipes 237 are of a hollow structure, one end of each of the plurality of support pipes 237 is communicated with the support housing 236, and the other end of each of the plurality of support pipes 237 is communicated with the lower jacket 221. Therefore, the heat medium in the support housing 236 flows into the lower jacket 221 through the plurality of support pipes 237 and is discharged.

[0049] Furthermore, one end of each of the plurality of support pipes 237 communicated with the lower jacket 221 is close to the heat medium outlet of the lower jacket 221, which increases the flow rate of the heat medium at the inlet of the lower jacket 221 and reduces the influence of the heat medium flowing out in the stirring shaft 234 on the heat in the lower jacket 221.

[0050] As Figure 1 shown, optionally, the hydrolysis tank gas treatment unit includes a first scrubbing tower 510 and an alkali solution tank 520. A second negative pressure fan 530 is connected between the lower air inlet of the first scrubbing tower 510 and the top air outlet of the hydrolysis tank 420. The alkali solution tank 520 is connected to the upper part of the first scrubbing tower 510 through a first spray pipe 540, and a first alkali solution spray pump 550 is arranged on the first spray pipe 540.

[0051] Specifically, the lye tank 520 supplies lye to the first scrubbing tower 510 for neutralizing the acidic gas (mainly hydrogen chloride) from the hydrolysis tank 420. The second negative pressure blower 530 pumps the acidic gas in the hydrolysis tank 420 to the first scrubbing tower 510, and the acidic gas moves upward in the first scrubbing tower 510. The first lye spraying pump 550 transports the lye in the lye tank 520 into the first scrubbing tower 510 through the first spray pipe 540 and atomizes and sprays it from top to bottom, enabling the acidic gas to come into countercurrent contact with the lye and undergo a neutralization reaction. The lye reacts with the hydrogen chloride gas to form a chloride salt, which falls to the bottom of the first scrubbing tower 510, achieving the harmless treatment of the hydrogen chloride gas, and the clean gas is discharged from the top of the first scrubbing tower 510. This avoids the pollution and corrosion of the environment caused by the discharge of hydrogen chloride and has good environmental protection benefits.

[0052] As Figure 3 shown, optionally, the hydrolysis tank gas treatment unit further includes a second scrubbing tower 610, a second spray pipe 620, and a second lye spraying pump 630. The lower air inlet of the second scrubbing tower 610 is connected to the top air outlet of the first scrubbing tower 510. The second spray pipe 620 is connected between the second scrubbing tower 610 and the lye tank 520, and the second lye spraying pump 630 is arranged on the second spray pipe 620.

[0053] Specifically, in order to absorb the hydrogen chloride gas as completely as possible, a second scrubbing tower 610 is connected in series to the top of the first scrubbing tower 510 through a gas pipeline. The lye in the lye tank 520 is transported into the second scrubbing tower 610 through the second spray pipe 620 by the second lye spraying pump 630. After the gas washed by the first scrubbing tower 510 is neutralized and washed again, it is discharged from the top of the second scrubbing tower 610.

[0054] Optionally, pH meters 640 are arranged in the bottoms of both the first scrubbing tower 510 and the second scrubbing tower 610. A first circulation pipeline 560 is connected between the bottom of the first scrubbing tower 510 and the first spray pipe 540, and a second circulation pipeline 650 is connected between the bottom of the second scrubbing tower 610 and the second spray pipe 620.

[0055] Specifically, the pH meter 640 can detect the pH value of the liquid in the bottom of the first scrubbing tower 510 and the second scrubbing tower 610. During the falling process of the lye from the lye tank 520 in the scrubbing tower, part of it reacts with hydrogen chloride, and there is still a part that does not react. Therefore, by detecting the acidity and alkalinity of the liquid in the bottom of the scrubbing tower with the pH meter 640, if the pH value shown by the pH meter is alkaline, the first circulation pipeline 560 and the second circulation pipeline 650 will return the liquid in the bottom of the scrubbing tower to the scrubbing tower. A first valve 561 is provided on the first circulation pipeline 560, a second valve 651 is provided on the second circulation pipeline 650, a first lye valve 541 is provided on the pipeline between the lye tank 520 and the first spray pipe 540, and a second lye valve 621 is provided on the pipeline between the lye tank 520 and the second spray pipe 620, which are used to control the passage of lye and the liquid in the bottom of the scrubbing tower into the scrubbing tower.

[0056] If the pH value shown by the pH meter is greater than or equal to 7, the first valve 561 and / or the second valve 651 are opened, and the first lye valve 541 and / or the second lye valve 621 are adjusted to be smaller. The liquid in the bottom of the first scrubbing tower 510 and / or the second scrubbing tower 610 and the lye are respectively returned to the first scrubbing tower 510 and / or the second scrubbing tower 610 through the first circulation pipeline 560 and / or the second circulation pipeline 650 via the first spray pipe 540 and / or the second spray pipe 620 for the neutralization of hydrogen chloride gas. If the pH value shown by the pH meter is less than 7, the first valve 561 and / or the second valve 651 are closed, and the first lye valve 541 and / or the second lye valve 621 are adjusted to be larger, and the lye in the lye tank 520 is used for the neutralization of hydrogen chloride gas in the scrubbing tower. In this way, the use of lye is reduced and the cost is saved.

[0057] Optionally, a vibrator 250 is provided on the outer side of the lower cone 220.

[0058] Specifically, when the cylinder-cone dryer 2 discharges materials through the discharge port at the bottom of the lower cone 220, the vibrator 250 is turned on to facilitate the rapid discharge of the internal solid residues.

[0059] The technical solution of the present application will be described in detail below with specific embodiments.

[0060] In the slurry treatment system during the production process of trichlorosilane in this embodiment, the operation process during specific work is as follows:

[0061] Powered by the slurry pump 120, the slurry is transported through the slurry pipeline 110 to the cylinder-cone dryer 2. Hot medium (the hot medium is hot water) is introduced into the upper jacket 211 and the lower jacket 221 to heat the slurry in the cylinder-cone dryer 2. Powered by the motor 231, the output shaft of the motor 231 drives the main gear 232 to rotate, the main gear 232 drives the driven gear 233 meshing with it to rotate, and further drives the stirring shaft 234 to rotate, so that the spiral stirring blades 2340 outside the stirring shaft 234 stir the slurry. At the same time, the hot medium also enters the stirring shaft 234 through the hot medium pipeline via the rotary joint 235, so that while stirring the slurry, the stirring shaft 234 also heats the slurry, and cooperates with the upper jacket 211 and the lower jacket 221 to heat the slurry simultaneously inside and outside. Trichlorosilane and silicon tetrachloride are evaporated into gases, sucked into the heat exchanger 310 by the first negative pressure fan 330 and condensed into liquids, and temporarily stored in the chlorosilane storage tank 320 for recycling.

[0062] After the evaporation in the cylinder-cone dryer 2 is completed, the vibrator 250 is started, and the remaining solid residues are transported to the hydrolysis tank 420 by the screw pump 410. At the same time, the solid materials obtained after hydrolysis in the hydrolysis tank 420 are transported to the filter press 450 through the rectification high-boiling pipeline 430 for pressure filtration. The obtained solid silicon dioxide and calcium chloride are recovered in the recovery tank 460 and can be added to concrete, building materials, etc. for waste utilization, reducing solid waste emissions. The liquid after pressure filtration by the filter press 450 is transported to the wastewater treatment station. The high-boiling substances in the last-stage rectification tower are transported to the hydrolysis tank 420 to dilute and adjust the slurry of the solid residues in the hydrolysis tank 420. A high-boiling substance valve 431 is provided on the rectification high-boiling pipeline 430 to control the transportation amount of the high-boiling substances. Then calcium oxide is added to the hydrolysis tank 420 through the calcium oxide addition tank 440. The high-polymer chlorosilane in the residues rapidly undergoes a hydrolysis reaction to generate silicon dioxide and calcium chloride. At the same time, hydrogen chloride gas will be generated during the hydrolysis process. The second negative pressure fan 530 sucks the acidic gas in the hydrolysis tank 420 into the first scrubbing tower 510, and the acidic gas moves from bottom to top in the first scrubbing tower 510. The first lye spray pump 550 transports the lye in the lye tank 520 to the first scrubbing tower 510 through the first spray pipe 540 and atomizes and sprays it from top to bottom. The acidic gas contacts the lye countercurrently, and the lye reacts with the hydrogen chloride gas to form chlorides and fall to the bottom of the first scrubbing tower 510. The second lye spray pump 630 transports the lye in the lye tank 520 to the second scrubbing tower 610 through the second spray pipe 620. After the gas washed by the first scrubbing tower 510 is neutralized and washed again, it is discharged from the top of the second scrubbing tower 610. The harmless treatment of hydrogen chloride gas is realized.

[0063] During the washing process, if the pH value shown by the pH meter is greater than or equal to 7, open the first valve 561 and / or the second valve 651, and turn down the first lye valve 541 and / or the second lye valve 621. Respectively send the liquid in the bottom of the first scrubbing tower 510 and / or the second scrubbing tower 610 and the lye back into the first scrubbing tower 510 and / or the second scrubbing tower 610 through the first circulation pipeline 560 and / or the second circulation pipeline 650 for the neutralization of hydrogen chloride gas via the first spray pipe 540 and / or the second spray pipe 620. If the pH value shown by the pH meter is less than 7, close the first valve 561 and / or the second valve 651, turn up the first lye valve 541 and / or the second lye valve 621, and use the lye in the lye tank 520 for the neutralization of hydrogen chloride gas in the scrubbing tower.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A treatment system for slurry in the production process of trichlorosilane, characterized in that, Comprising: An evaporation unit, a chlorosilane recovery unit, a hydrolysis unit, and a hydrolysis tank gas treatment unit; The evaporation unit includes a slurry pool (1) and a cylinder-cone dryer (2) connected to the slurry pool (1) through a slurry pipeline (110), and a slurry pump (120) is arranged on the slurry pipeline (110); The chlorosilane recovery unit includes a heat exchanger (310) and a chlorosilane storage tank (320). The air inlet of the heat exchanger (310) is communicated with the top air outlet of the cylinder-cone dryer (2) through a first negative pressure fan (330), and the liquid outlet of the heat exchanger (310) is communicated with the chlorosilane storage tank (320); The hydrolysis unit includes a screw pump (410), a hydrolysis tank (420), a rectification high-boiling pipeline (430), and a calcium oxide addition tank (440). The inlet end of the screw pump (410) is connected to the bottom outlet of the cylinder-cone dryer (2), the outlet end of the screw pump (410) is connected to the upper feed port of the hydrolysis tank (420), the outlet end of the rectification high-boiling pipeline (430) is connected to the upper feed port of the hydrolysis tank (420), the calcium oxide addition tank (440) is communicated with the top of the hydrolysis tank (420), and the hydrolysis tank gas treatment unit is connected to the top air outlet of the hydrolysis tank (420).

2. The treatment system for the slurry in the trichlorosilane production process according to claim 1, wherein, The bottom outlet of the hydrolysis tank (420) is connected to a filter press (450), and a solid-phase recovery tank (460) is connected to the solid-phase outlet of the filter press (450).

3. The slurry treatment system in the trichlorosilane production process according to claim 1, characterized in that The cylinder-cone dryer (2) includes an upper cylinder body (210), a lower cone body (220), and a stirring unit. The upper cylinder body (210) is connected to the lower cone body (220) through a flange (201). An upper jacket (211) is arranged outside the upper cylinder body (210), a lower jacket (221) is arranged outside the lower cone body (220), and the stirring unit is arranged in a drying cavity (202) formed by the upper cylinder body (210) and the lower cone body (220).

4. The treatment system for the slurry in the trichlorosilane production process according to claim 3, characterized in that, The stirring unit includes a motor (231), a main gear (232), a driven gear (233), a stirring shaft (234), a rotary joint (235), a support housing (236), and a plurality of support pipes (237); The motor (231) is fixed to the top of the cylinder-cone dryer (2) by bolts. The main gear (232) is fixedly sleeved on the output shaft of the motor (231). The main gear (232) is meshed and connected with the driven gear (233). The driven gear (233) is fixedly sleeved on the stirring shaft (234). The inlet end of the rotary joint (235) is connected to a heat medium pipeline. The outlet end of the rotary joint (235) is connected to one end of the stirring shaft (234) close to the driven gear (233). The other end of the stirring shaft (234) vertically extends into the cylinder-cone dryer (2), and a spiral stirring paddle (2340) is arranged outside the stirring shaft (234); The lower end of the stirring shaft (234) extends into the support housing (236). One end of each of the plurality of support pipes (237) communicates with the support housing (236), and the other end of each of the plurality of support pipes (237) communicates with the lower jacket (221). The connection between the stirring shaft (234) and the support housing (236) is sealed by a bearing (238).

5. The treatment system for the slurry in the trichlorosilane production process according to any one of claims 1-4, characterized in that, The hydrolysis tank gas treatment unit includes a first scrubbing tower (510) and an alkali solution tank (520). A second negative pressure fan (530) is connected between the lower air inlet of the first scrubbing tower (510) and the top air outlet of the hydrolysis tank (420). The alkali solution tank (520) is connected to the upper part of the first scrubbing tower (510) through a first spray pipe (540), and a first alkali solution spray pump (550) is arranged on the first spray pipe (540).

6. The slurry treatment system in the trichlorosilane production process according to claim 5, characterized in that, The hydrolysis tank gas treatment unit further includes a second scrubbing tower (610), a second spray pipe (620) and a second alkali solution spray pump (630). The lower air inlet of the second scrubbing tower (610) is connected to the top air outlet of the first scrubbing tower (510). The second spray pipe (620) is connected between the second scrubbing tower (610) and the alkali solution tank (520), and the second alkali solution spray pump (630) is arranged on the second spray pipe (620).

7. The treatment system for slurry in the trichlorosilane production process according to claim 6, wherein, pH meters (640) are arranged in the bottom parts of both the first scrubbing tower (510) and the second scrubbing tower (610). A first circulation pipeline (560) is connected between the bottom part of the first scrubbing tower (510) and the first spray pipe (540), and a second circulation pipeline (650) is connected between the bottom part of the second scrubbing tower (610) and the second spray pipe (620).

8. The treatment system for the slurry in the trichlorosilane production process according to claim 3, characterized in that, Vibrators (250) are arranged on the outer side of the lower cone (220).

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