Separation device for silicon nitride filtrate

Abstract

The utility model discloses a silicon nitride filtrate separation device which comprises a storage tank, a liquid separation tank, a liquid ammonia heater, an ammonium chloride evaporation crystallizer, an ammonium chloride recrystallization kettle, a rectifying tower and a methylbenzene stripping tower, the storage tank is used for storing a mixed solution of methylbenzene, liquid ammonia and ammonium chloride, and the liquid separation tank is used for separating liquid of methylbenzene and an ammonium chloride-liquid ammonia solution; a liquid inlet of the liquid separation tank is connected with a liquid outlet of the storage tank through a pipeline, the liquid ammonia heater is used for heating an ammonium chloride-liquid ammonia solution, a liquid inlet of the liquid ammonia heater is connected with a second liquid outlet of the liquid separation tank through a pipeline, and the ammonium chloride evaporation crystallizer is used for evaporating the ammonium chloride-liquid ammonia solution and evaporating ammonia gas. According to the device, a liquid separation method is adopted, under the condition that the liquid state is kept, a large amount of methylbenzene and liquid ammonia solution are preliminarily separated, the content of ammonia in the methylbenzene is reduced, the content of the methylbenzene in the liquid ammonia is also reduced, the recovery efficiency is improved, and the energy consumption is reduced.

Description

Technical Field

[0001] This utility model relates to the field of waste liquid recycling technology, specifically a separation device for silicon nitride filtrate. Background Technology

[0002] The liquid-phase synthesis of powders generates a large amount of soluble byproducts, and the solvent consumption is substantial and may be diverse. These mixtures contain organic solvents and liquid ammonia, which cannot be directly discharged, and their harmless treatment is costly. Therefore, achieving effective separation and recovery of various solvents and byproducts, reducing raw material consumption, and lowering costs are of great significance for energy conservation, environmental protection, improving economic efficiency, and sustainable development.

[0003] The mixed solution of toluene, liquid ammonia, and ammonium chloride originates from a liquid-phase synthesis process. Toluene and liquid ammonia are immiscible solvents, while ammonium chloride, a byproduct, dissolves in liquid ammonia to form an ammonium chloride-liquid ammonia solution. Current processes mostly perform preliminary separation of the three components, resulting in incomplete separation. For example, toluene obtained solely through liquid-liquid separation contains significant amounts of liquid ammonia and ammonia gas, which, if reused, would greatly hinder the reaction process. Currently, there is no mature process for separating high-purity toluene, liquid ammonia, and ammonium chloride. If distillation is used to separate toluene, liquid ammonia, and ammonium chloride, both need to be vaporized simultaneously, requiring high energy consumption. During vaporization, a large amount of ammonium chloride precipitates at the bottom of the distillation column, affecting process continuity. Furthermore, ammonium chloride is highly corrosive, placing high demands on equipment, and the quality of the ammonium chloride is difficult to meet environmental protection requirements.

[0004] To address the aforementioned waste liquid recycling problem, developing a method with low energy consumption, high processing capacity, and high-purity material recovery is a breakthrough in reducing the cost of powder preparation using the liquid phase method. Therefore, it is urgent to design a separation device for silicon nitride filtrate to solve the above problems. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a separation device for silicon nitride filtrate, which aims to solve the problems of incomplete separation of various materials and high energy consumption in the process of waste liquid recycling.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A separation device for silicon nitride filtrate, comprising:

[0008] A storage tank for storing a mixed solution of toluene, liquid ammonia, and ammonium chloride;

[0009] The separator is used to separate toluene and ammonium chloride-liquid ammonia solution. The inlet of the separator is connected to the outlet of the storage tank via a pipeline.

[0010] A liquid ammonia heater, wherein the liquid ammonia heater is used to heat an ammonium chloride-liquid ammonia solution, and the inlet of the liquid ammonia heater is connected to the second outlet of the separator via a pipeline;

[0011] An ammonium chloride evaporator crystallizer is used to evaporate an ammonium chloride-liquid ammonia solution, evaporate ammonia gas, and precipitate ammonium chloride crystals. The inlet of the ammonium chloride evaporator crystallizer is connected to the outlet of the liquid ammonia heater through a pipeline.

[0012] An ammonium chloride recrystallization kettle, wherein the ammonium chloride crystals precipitated in the ammonium chloride evaporator are transferred to the ammonium chloride recrystallization kettle for recrystallization and purification;

[0013] A distillation column, wherein the inlet of the distillation column is connected to the outlet of the ammonium chloride evaporator crystallizer via a pipeline, and the distillation column is used to distill ammonia gas to obtain high-purity ammonia;

[0014] The toluene stripping tower has its inlet connected to the first outlet of the separator via a pipeline, and its outlet connected to a toluene collection tank via a pipeline.

[0015] Preferably, the interior of the separator is divided into a toluene chamber and an ammonium chloride-liquid ammonia solution chamber by an overflow baffle, the second outlet is placed in the ammonium chloride-liquid ammonia solution chamber, and the inlet and the first outlet are placed in the toluene chamber.

[0016] Preferably, the outlet of the ammonium chloride recrystallization reactor is connected to an ammonium chloride collection tank via a pipeline.

[0017] Preferably, the outlet of the distillation column is connected to an ammonia condenser via a pipeline, and the outlet of the ammonia condenser is connected to a liquid ammonia collection tank via a pipeline.

[0018] Preferably, the liquid outlet at the bottom of the distillation column is connected to the liquid return port of the storage tank via a pipeline, which is used to send the residual liquid at the bottom of the distillation column back to the storage tank for further separation.

[0019] Preferably, the inlet of the toluene stripping tower is connected to a nitrogen source via a pipeline, and the nitrogen source provides nitrogen gas as purging gas to the toluene stripping tower.

[0020] Preferably, the tail gas outlet of the toluene stripping tower is connected to a toluene condenser via a pipeline, and the liquid outlet of the toluene condenser is connected to the reflux outlet of the toluene stripping tower via a pipeline.

[0021] Compared with the prior art, the beneficial effects of this utility model are:

[0022] 1. This utility model adopts a liquid separation method to initially separate a large amount of toluene and liquid ammonia solution while maintaining the liquid state, thereby reducing the ammonia content in toluene and the toluene content in liquid ammonia, improving recovery efficiency and reducing energy consumption.

[0023] 2. After liquid-phase separation, ammonium chloride and liquid ammonia still contain a small amount of toluene. High-purity ammonia is obtained through distillation, and the recovered liquid ammonia has a purity of 99% to 99.99%. Ammonium chloride crystals are precipitated by evaporation, water dissolution, and recrystallization to obtain high-purity salt with a purity of 99% to 99.9%.

[0024] 3. After liquid phase separation, the toluene contains a small amount of liquid ammonia and ammonia gas. High-temperature nitrogen purging is used to rapidly vaporize the liquid ammonia and allow the ammonia gas to escape with the nitrogen gas, thereby improving the purity of the recovered toluene. The purity of the toluene can reach 99% to 99.99%. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the separation device for silicon nitride filtrate.

[0026] In the diagram: 1. Storage tank; 2. Separator; 3. Liquid ammonia heater; 4. Ammonium chloride evaporator crystallizer; 5. Ammonium chloride recrystallization kettle; 6. Ammonia condenser; 7. Liquid ammonia collection tank; 8. Toluene stripping tower; 9. Toluene condenser; 10. Nitrogen source; 11. Toluene collection tank; 12. Distillation tower; 13. Ammonium chloride collection tank. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0028] Please see Figure 1 This embodiment provides a separation device for silicon nitride filtrate, used to recover liquid toluene, liquid ammonia and solid ammonium chloride powder from a mixed solution of toluene, liquid ammonia and ammonium chloride. In particular, it separates a mixture of toluene with a mass percentage concentration of 10-50%, liquid ammonia of 40-90% and ammonium chloride of 2-30%. It solves the problem of low separation efficiency caused by the solid-liquid-gas system in the separation process of toluene, liquid ammonia and ammonium chloride mixed solution. The separation device for silicon nitride filtrate includes a storage tank 1, a separating tank 2, a liquid ammonia heater 3, an ammonium chloride evaporator crystallizer 4, an ammonium chloride recrystallization kettle 5, a distillation column 12 and a toluene stripping column 8.

[0029] In this embodiment, a mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from the production unit to storage tank 1 via pipeline for temporary storage. Storage tank 1 is used to store the mixed solution of toluene, liquid ammonia, and ammonium chloride, and storage tank 1 is provided with an outlet located at the bottom.

[0030] In this embodiment, the separator 2 is divided into a toluene chamber and an ammonium chloride-liquid ammonia solution chamber by an overflow baffle. The separator 2 is provided with an inlet at the top, a toluene outlet and a liquid ammonia outlet at the bottom. The inlet of the separator 2 is connected to the outlet of the storage tank 1 by a pipe. The liquid ammonia outlet is placed in the ammonium chloride-liquid ammonia solution chamber, and the inlet and toluene outlet are placed in the toluene chamber. The separator 2 is used to separate toluene and ammonium chloride-liquid ammonia solution. The mixed solution of toluene, liquid ammonia and ammonium chloride enters the separator 2 from the storage tank 1. The separator 2 is equipped with a viewing window. Toluene settles to the lower layer and is released from the toluene outlet at the bottom of the separator 2. As the amount of mixed solution entering the separator 2 increases, the ammonium chloride-liquid ammonia solution floating on the toluene layer overflows the overflow baffle and flows out from the liquid ammonia outlet.

[0031] In this embodiment, the liquid ammonia heater 3 is provided with an inlet and an outlet. The inlet of the liquid ammonia heater 3 is connected to the liquid ammonia outlet of the separator 2 through a pipe. The liquid ammonia heater 3 is used to heat the ammonium chloride-liquid ammonia solution. The ammonium chloride evaporator crystallizer 4 is provided with an inlet and an outlet at the top and a outlet at the bottom. The inlet of the ammonium chloride evaporator crystallizer 4 is connected to the outlet of the liquid ammonia heater 3 through a pipe. The ammonium chloride evaporator crystallizer 4 is used to evaporate the ammonium chloride-liquid ammonia solution, evaporate ammonia gas, and precipitate ammonium chloride crystals. The separated ammonium chloride-liquid ammonia solution flows into the liquid ammonia heat exchanger 3 for heating. The heat exchange temperature is 0-60°C. The heated ammonium chloride-liquid ammonia solution enters the ammonium chloride evaporator crystallizer 4. The evaporation temperature is 10-80°C, the evaporation time is 0.5-8 hours, and the stirring speed is 0-500 rpm, so that the liquid ammonia evaporates into ammonia gas, and a large amount of ammonium chloride crystals dissolved in the liquid ammonia precipitate out.

[0032] In this embodiment, the ammonium chloride recrystallization vessel 5 is equipped with a feed inlet at the top and a discharge outlet at the bottom. The discharge outlet of the ammonium chloride evaporator crystallizer 4 is connected to the feed inlet of the ammonium chloride recrystallization vessel 5 through a pipeline. The ammonium chloride crystals precipitated in the ammonium chloride evaporator crystallizer 4 are transferred to the ammonium chloride recrystallization vessel 5 for recrystallization and purification. The discharge outlet of the ammonium chloride recrystallization vessel 5 is connected to the ammonium chloride collection tank 13 through a pipeline. After the liquid ammonia in the ammonium chloride evaporator crystallizer 4 has completely evaporated, the precipitated ammonium chloride crystals are transferred to the ammonium chloride recrystallization vessel 5, a certain amount of ultrapure water is introduced, the temperature is raised to 60-100°C, stirred and dissolved, and then cooled to 10-50°C. High-purity ammonium chloride crystals are obtained by filtration. The remaining solution can be used to dissolve the next batch of ammonium chloride crystals. The high-purity ammonium chloride crystals are collected and used in the ammonium chloride collection tank 13.

[0033] In this embodiment, the distillation column 12 is provided with an inlet and a liquid outlet at the bottom and an outlet at the top. The inlet of the distillation column 12 is connected to the outlet of the ammonium chloride evaporator crystallizer 4 via a pipeline. The distillation column 12 is used to distill ammonia gas to obtain high-purity ammonia. The liquid outlet at the bottom of the distillation column 12 is connected to the return liquid outlet of the storage tank 1 via a pipeline, which is used to send the residual liquid at the bottom of the distillation column 12 back to the storage tank 1 for further separation. The outlet of the distillation column 12 is connected to an ammonia condenser via a pipeline. 6. The outlet of the ammonia condenser 6 is connected to the liquid ammonia collection tank 7 via a pipeline. Ammonia gas is evaporated in the ammonium chloride evaporator crystallizer 4 and enters the distillation column 12. The distillation temperature is 40-80℃. After distillation, high-purity ammonia is obtained. The residual liquid at the bottom of the distillation column 12 is sent back to the storage tank 1 for further separation. The high-purity ammonia is then introduced into the ammonia condenser 6. The condensation temperature is -40-20℃ and the pressure is 0-1.0MPa. The ammonia gas is condensed into liquid ammonia, which is collected in the liquid ammonia collection tank 7 for reuse.

[0034] In this embodiment, the toluene stripping tower 8 is provided with a liquid inlet, a tail gas outlet, and a reflux outlet at the top, and a liquid outlet and a gas inlet at the bottom. The liquid inlet of the toluene stripping tower 8 is connected to the toluene outlet of the separator 2 via a pipeline. The liquid outlet of the toluene stripping tower 8 is connected to a toluene collection tank 11 via a pipeline. The gas inlet of the toluene stripping tower 8 is connected to a nitrogen source 10 via a pipeline. The nitrogen source 10 provides nitrogen gas as a purging gas to the toluene stripping tower 8. The tail gas outlet of the toluene stripping tower 8 is connected to a toluene cooler via a pipeline. The outlet of the toluene condenser 9 is connected to the reflux port of the toluene stripping tower 8 via a pipeline. The toluene separated in the separator 2 is fed from the top of the stripping tower 8. Nitrogen source 10 provides nitrogen as a purging gas, which enters the stripping tower 8 for gas-liquid two-phase exchange. The nitrogen temperature is 30-100℃. The tail gas in the benzene stripping tower 8 enters the toluene condenser 9. The toluene is condensed and refluxed back to the stripping tower 8. When the ammonia content in the toluene drops to 0.1% or below, it is released from the bottom of the toluene stripping tower 8 into the toluene collection tank 11 for reuse.

[0035] Specific Implementation Cases

[0036] Example 1

[0037] A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from the production unit to storage tank 1 via pipeline for temporary storage.

[0038] The temperature of liquid ammonia heater 3 is raised to 60℃, ammonium chloride evaporator crystallizer 4 is kept at 60℃, ammonium chloride recrystallization kettle 5 is raised to 80℃, distillation column 12 is raised to 50℃, ammonia condenser 6 is lowered to -10℃, toluene stripping column 8 is introduced with 60℃ nitrogen gas, and toluene condenser 9 is lowered to 7℃.

[0039] A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from storage tank 1 to separator 2. The upper layer of ammonium chloride-liquid ammonia solution is then transported from the liquid ammonia outlet of separator 2 to a liquid ammonia heater 3 for heating. The heated ammonium chloride-liquid ammonia solution is then piped to an ammonium chloride evaporator crystallizer 4, where it is stirred and heated to evaporation at 60°C for 2 hours. Ammonium chloride powder precipitates from the liquid ammonia and accumulates at the bottom of the ammonium chloride evaporator crystallizer 4. The ammonia gas, obtained from the vaporization of liquid ammonia, is piped to a distillation column 12. The distilled ammonia gas then enters an ammonia condenser 6. The condensed liquid ammonia contains 99% ammonia and 1% toluene. After evaporating liquid ammonia for 2 hours, the temperature of ammonium chloride evaporator crystallizer 4 is increased to vacuum dry the ammonium chloride powder at 80°C for 1 hour. The toluene content in the dried ammonium chloride is 180 ppm. The toluene separated from the bottom of separator 2 is transported to toluene stripping tower 8 through a pipeline. Nitrogen source 10 provides nitrogen gas at 60°C, which is used to purge the bottom of toluene stripping tower 8. The toluene tail gas enters toluene condenser 9 from the top of toluene stripping tower 8 at a condensation temperature of 7°C. The condensed toluene is returned to toluene stripping tower 8 for further purification. The ammonia content in the purified toluene is <0.5%.

[0040] Example 2

[0041] A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from the production unit to storage tank 1 via pipeline for temporary storage.

[0042] The temperature of liquid ammonia heater 3 is raised to 20℃, ammonium chloride evaporator crystallizer 4 is kept at 50℃, the temperature of ammonia condenser 6 is lowered to -10℃, and nitrogen gas at 80℃ is introduced into toluene stripping tower 8. Toluene condenser 9 is cooled to 7℃.

[0043] A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from storage tank 1 to separator 2. The upper layer of ammonium chloride-liquid ammonia solution is then transported from the liquid ammonia outlet of separator 2 to a liquid ammonia heater 3 for heating. The heated ammonium chloride-liquid ammonia solution is then piped to an ammonium chloride evaporator crystallizer 4. During stirring, ammonium chloride powder precipitates from the liquid ammonia and accumulates at the bottom of the evaporator crystallizer 4. The mixture is then heated and evaporated at 50°C for 4 hours. The vaporized ammonia gas is piped to an ammonia condenser 6. The condensed liquid has an ammonia purity of 99.5% and a toluene content of 0.5%. The liquid ammonia evaporates... Four hours later, the temperature of ammonium chloride evaporator crystallizer 4 was increased to vacuum dry the ammonium chloride powder at 80°C for 2 hours. The toluene content in the dried ammonium chloride was 100 ppm. The toluene separated from the bottom of separator 2 was transported to toluene stripping tower 8 through a pipeline. Nitrogen source 10 provided nitrogen gas at 80°C to purge from the bottom of toluene stripping tower 8. The toluene tail gas entered toluene condenser 9 from the top of toluene stripping tower 8 at a condensation temperature of 7°C. The condensed toluene was returned to toluene stripping tower 8 for further purification. The ammonia content in the purified toluene was <0.4%.

[0044] Example 3

[0045] A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from the production unit to storage tank 1 via pipeline for temporary storage.

[0046] The temperature of liquid ammonia heater 3 is raised to 60℃, ammonium chloride evaporator crystallizer 4 is kept at 40℃, ammonia condenser 6 is lowered to -10℃, nitrogen gas at 90℃ is introduced into toluene stripping tower 8, and toluene condenser 9 is cooled to 0℃. A mixed solution of toluene, liquid ammonia, and ammonium chloride is transported from storage tank 1 to separator 2. The upper layer of ammonium chloride-liquid ammonia solution is transported from the liquid ammonia outlet of separator 2 to liquid ammonia heater 3 for heating. The heated ammonium chloride-liquid ammonia solution is then transported via pipeline to ammonium chloride evaporator crystallizer 4. Under stirring, ammonium chloride powder precipitates from the liquid ammonia and accumulates at the bottom of ammonium chloride evaporator crystallizer 4. It is then heated and evaporated at 40℃ for 2 hours. The vaporized ammonia gas is then transported via pipeline to the ammonia... In the gas condenser 6, the condensed liquid ammonia content is 99.9% and the toluene content is 0.1%. After the liquid ammonia evaporates for 2 hours, the temperature of the ammonium chloride evaporator crystallizer 4 is increased to vacuum dry the ammonium chloride powder at 90℃ for 2 hours. The toluene content in the dried ammonium chloride is 70ppm. The toluene separated from the bottom of the separator 2 is transported to the toluene stripping tower 8 through a pipeline. Nitrogen source 10 provides nitrogen gas at 90℃, which is used to purge the bottom of the toluene stripping tower 8. The toluene tail gas enters the toluene condenser 9 from the top of the toluene stripping tower 8 at 0℃. The condensed toluene is returned to the toluene stripping tower 8 for further purification. The ammonia content in the purified toluene is <0.2%.

[0047] This embodiment employs a liquid-liquid separation method. While maintaining the liquid state, a large quantity of toluene and liquid ammonia solutions are initially separated, reducing the ammonia content in both toluene and liquid ammonia, thus improving recovery efficiency and reducing energy consumption. After liquid-phase separation, ammonium chloride and liquid ammonia still contain small amounts of toluene. High-purity ammonia is obtained through distillation, with the recovered liquid ammonia having a purity of 99%–99.99%. Ammonium chloride crystals are precipitated using evaporation, water dissolution, and recrystallization to obtain high-purity salt with a purity of 99%–99.9%. After liquid-phase separation, toluene contains small amounts of liquid ammonia and ammonia gas. High-temperature nitrogen purging is used to rapidly vaporize the liquid ammonia, with the ammonia gas escaping with the nitrogen gas, thus improving the purity of the recovered toluene, which can reach 99%–99.99%.

[0048] The above embodiments are preferred implementations of this utility model. In addition, this utility model can also be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.

Claims

1. A separation apparatus for a silicon nitride filtrate, characterized by, The application relates to a device for separating and purifying a mixed solution of toluene, liquid ammonia and ammonium chloride. The device comprises a storage tank (1) for storing the mixed solution of toluene, liquid ammonia and ammonium chloride; a separation tank (2) for separating the toluene and the ammonium chloride-liquid ammonia solution, the liquid inlet of the separation tank (2) being connected to the liquid outlet of the storage tank (1) through a pipeline; a liquid ammonia heater (3) for heating the ammonium chloride-liquid ammonia solution, the liquid inlet of the liquid ammonia heater (3) being connected to the liquid ammonia outlet of the separation tank (2) through a pipeline; an ammonium chloride evaporation crystallizer (4) for evaporating the ammonium chloride-liquid ammonia solution, discharging ammonia gas and precipitating ammonium chloride crystals, the liquid inlet of the ammonium chloride evaporation crystallizer (4) being connected to the liquid outlet of the liquid ammonia heater (3) through a pipeline; an ammonium chloride recrystallization kettle (5), the discharge outlet of the ammonium chloride evaporation crystallizer (4) being connected to the feeding inlet of the ammonium chloride recrystallization kettle (5) through a pipeline, and the ammonium chloride crystals precipitated from the ammonium chloride evaporation crystallizer (4) being transferred into the ammonium chloride recrystallization kettle (5) for recrystallization and purification; a rectifying tower (12), the gas inlet of the rectifying tower (12) being connected to the gas outlet of the ammonium chloride evaporation crystallizer (4) through a pipeline, and the rectifying tower (12) being used for rectifying the ammonia gas to obtain high-purity ammonia; a toluene stripping tower (8), the liquid inlet of the toluene stripping tower (8) being connected to the toluene outlet of the separation tank (2) through a pipeline, and the liquid outlet of the toluene stripping tower (8) being connected to a toluene collecting tank (11) through a pipeline. The inside of the separation tank (2) is divided into a toluene cavity and an ammonium chloride-liquid ammonia solution cavity by an overflow partition, the liquid ammonia outlet is arranged in the ammonium chloride-liquid ammonia solution cavity, and the liquid inlet and the toluene outlet are arranged in the toluene cavity. The discharge outlet of the ammonium chloride recrystallization kettle (5) is connected to an ammonium chloride collecting tank (13) through a pipeline. The gas outlet of the rectifying tower (12) is connected to an ammonia gas condenser (6) through a pipeline, and the gas outlet of the ammonia gas condenser (6) is connected to a liquid ammonia collecting tank (7) through a pipeline. The liquid outlet at the bottom of the rectifying tower (12) is connected to the liquid return port of the storage tank (1) through a pipeline, so as to send the residual liquid at the bottom of the rectifying tower (12) back to the storage tank (1) for continuous separation. The gas inlet of the toluene stripping tower (8) is connected to a nitrogen source (10) through a pipeline, and the nitrogen source (10) provides nitrogen gas as a purge gas in the toluene stripping tower (8). The tail gas discharge outlet of the toluene stripping tower (8) is connected to a toluene condenser (9) through a pipeline, and the liquid outlet of the toluene condenser (9) is connected to the reflux port of the toluene stripping tower (8) through a pipeline.

2. The apparatus for separating a silicon nitride filtrate according to claim 1, characterized by: ​ 3. The apparatus for separating a silicon nitride filtrate according to claim 1, characterized by: ​ 4. The apparatus for separating a silicon nitride filtrate according to claim 1, characterized by: ​ 5. The apparatus for separating a silicon nitride filtrate according to claim 1, wherein: ​ 6. The apparatus for separating a silicon nitride filtrate according to claim 1, wherein: ​ 7. The apparatus for separating a silicon nitride filtrate according to claim 1, wherein: ​

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