Recovery system and recovery method for continuously recovering hydrazine hydrate

Abstract

The invention relates to the technical field of hydrazine hydrate recovery, and particularly discloses a recovery system and a recovery method for continuously recovering hydrazine hydrate. The recovery system for continuously recovering hydrazine hydrate comprises a waste liquid pipe, an alkali liquor pipe, a solvent pipe, a neutralizer, a preheater, a scraper film evaporator, a solid-liquid separation device, a rectifying tower and a hydrazine hydrate receiving container. The waste liquid pipe, the alkali liquor pipe and the solvent pipe are respectively connected with the neutralizer. And the neutralizer is connected with the preheater. And the preheater is connected with the scraper film evaporator. And the upper end of the scraper film evaporator is connected with the middle part of the rectifying tower. The lower end of the rectifying tower is connected with a hydrazine hydrate receiving container. According to the system, hydrazine hydrate can be continuously recovered, the production efficiency is high, the concentration of the obtained hydrazine hydrate solution is high, the retention time of hydrazine hydrate in the system is short, and the problem of hydrazine hydrate polymerization is basically avoided.

Description

Technical Field

[0001] This application relates to the technical field of hydrazine hydrate recovery, and particularly relates to a recovery system and a recovery method for continuously recovering hydrazine hydrate. Background Art

[0002] 3-Chloro-2-hydrazinopyridine is a very important fine chemical intermediate and a key intermediate for synthesizing chlorantraniliprole. 3-Chloro-2-hydrazinopyridine is synthesized by reacting 2,3-dichloropyridine and hydrazine hydrate. An excessive amount of hydrazine hydrate is used in the synthesis process. The hydrogen chloride generated during the reaction combines with hydrazine hydrate to form hydrazine hydrate hydrochloride. After centrifugation after the reaction, there will be a large amount of hydrazine hydrate hydrochloride and hydrazine hydrate in the centrifugation mother liquor. If not recovered and utilized, it will cause a large amount of waste of hydrazine hydrate, indirectly increase production costs, and is also not conducive to environmental protection. The related processes for recovering hydrazine hydrate all use traditional batch distillation in a kettle, resulting in a low concentration of hydrazine hydrate, low production efficiency, and the polymerization of hydrazine hydrate due to the long-term distillation of materials in the kettle. Summary of the Invention

[0003] In view of the problems that the related processes for recovering hydrazine hydrate all use traditional batch distillation in a kettle, resulting in a low concentration of hydrazine hydrate, low production efficiency, and the polymerization of hydrazine hydrate due to the long-term distillation of materials in the kettle, this application proposes a recovery system and a recovery method for continuously recovering hydrazine hydrate, with a high concentration of recovered hydrazine hydrate and high production efficiency.

[0004] In the first aspect, this application proposes a recovery system for continuously recovering hydrazine hydrate and adopts the following technical solutions.

[0005] A recovery system for continuously recovering hydrazine hydrate includes a waste liquid pipe, an alkali liquid pipe, a solvent pipe, a neutralizer, a preheater, a wiped film evaporator, a solid-liquid separation device, a rectifying column, and a hydrazine hydrate receiving container.

[0006] The waste liquid pipe, the alkali liquid pipe, and the solvent pipe are respectively connected to the neutralizer. The neutralizer is connected to the preheater. The preheater is connected to the wiped film evaporator. The lower end of the wiped film evaporator is connected to the solid-liquid separation device, and the upper end is connected to the middle part of the rectifying column. The lower end of the rectifying column is connected to the hydrazine hydrate receiving container.

[0007] By adopting the above technical solution, the waste liquid pipe can be used to pass the waste liquid containing hydrazine hydrochloride, the alkali liquid pipe passes the alkali liquid, the neutralizer is used for the neutralization reaction of hydrazine hydrochloride and the alkali liquid, so that hydrazine hydrochloride decomposes into hydrazine and salt, the solvent pipe passes the solvent to wash the salt during the recovery process, and the salt is brought to the separation device to facilitate the separation and removal of the salt. The preheater can preheat the treated liquid added with the solvent after neutralization, so as to quickly evaporate hydrazine after passing into the wiped film evaporator. After evaporation, it is passed into the rectification column to separate high-concentration hydrazine. This system can produce continuously, with high production efficiency, short residence time of hydrazine in the system, and basically no problem of hydrazine polymerization.

[0008] A preferred solution of the recovery system for continuously recovering hydrazine hydrate is that the solid-liquid separation device includes a receiver with a stirring mechanism, a feeding pump, a centrifuge and a protective gas supplier. The receiver is connected to the lower end of the wiped film evaporator. The feeding pump is connected to the receiver and the centrifuge. The protective gas supplier is connected to the centrifuge.

[0009] By adopting the above technical solution, the receiver collects the residual liquid, which is pumped to the centrifuge by the feeding pump after stirring. The protective gas supplier fills the centrifuge with protective gas to prevent the hydrazine hydrate contained in the residual liquid from coming into contact with air and causing combustion and explosion during stirring.

[0010] A preferred solution of the recovery system for continuously recovering hydrazine hydrate is that the recovery system further includes a condenser, a water receiving container and a vacuum pump. The upper end of the rectification column is connected to one side of the upper end of the condenser. The vacuum pump is connected to the other side of the upper end of the condenser. The water receiving container is connected to the lower end of the condenser.

[0011] By adopting the above technical solution, the vacuum pump pumps air to introduce the water vapor at the upper end of the rectification column into the condenser. The water vapor condenses into liquid water and flows into the water receiving container to be recovered.

[0012] A preferred solution of the recovery system for continuously recovering hydrazine hydrate is that a stirrer and a pH detector are installed in the neutralizer.

[0013] By adopting the above technical solution, the stirrer is used to stir the solution, promote the progress of the neutralization reaction, and disperse the salt generated by the reaction in the solvent. The pH detector is used to detect the pH of the treated liquid to confirm that hydrazine hydrochloride is completely neutralized to form hydrazine hydrate, so as to improve the recovery rate.

[0014] In a second aspect, the present application also proposes a recovery method for continuously recovering hydrazine hydrate and adopts the following technical solutions.

[0015] A method for continuously recovering hydrazine hydrate uses the above-mentioned recovery system to recover hydrazine hydrate. The recovery method includes: adding the waste liquid containing hydrazine hydrate hydrochloride into the neutralizer through the waste liquid pipe, adding alkali solution into the neutralizer through the alkali solution pipe, so that the pH of the waste liquid in the neutralizer is 10-13. Adding ethylene glycol into the neutralizer through the solvent pipe to obtain a treatment liquid.

[0016] Pass the treatment liquid in the neutralizer into the preheater for preheating.

[0017] Turn on the vacuum pump to evacuate the condenser, the distillation column and the wiped film evaporator.

[0018] Pass the preheated treatment liquid into the wiped film evaporator. The wiped film evaporator performs scraping treatment and heating on the treatment liquid, so that hydrazine hydrate and water in the treatment liquid evaporate and enter the distillation column, and ethylene glycol does not evaporate. The residual liquid of the treatment liquid enters the solid-liquid separation device.

[0019] The distillation column rectifies the mixed steam of hydrazine hydrate and water entering, so that water vapor flows out from above, and hydrazine hydrate condenses and enters the hydrazine hydrate receiving container.

[0020] By adopting the above technical solution, the process of recovering hydrazine hydrate is continuous production, with high output efficiency, high recovery rate, and high concentration of the obtained hydrazine hydrate.

[0021] A preferred scheme of the continuous recovery method of hydrazine hydrate is that the mass ratio of the ethylene glycol to the waste liquid is 1:(3.5-5.5).

[0022] By adopting the above technical solution, the salt generated after the hydrazine hydrate hydrochloride in the waste liquid is neutralized can be washed and dispersed in ethylene glycol by ethylene glycol and brought into the solid-liquid separation device.

[0023] A preferred scheme of the continuous recovery method of hydrazine hydrate is that the preheater is heated to 70-90°C.

[0024] By adopting the above technical solution, after the treatment liquid is preheated to this temperature and then enters the wiped film evaporator, it can be further heated and film-scraped for evaporation, with high recovery rate and relatively energy-saving.

[0025] A preferred scheme of the continuous recovery method of hydrazine hydrate is that the temperature of the wiped film evaporator is 90-130°C and the internal air pressure is 5-10 kPa.

[0026] By adopting the above technical solution, at this temperature and air pressure, in cooperation with the liquid film scraping method, hydrazine hydrate in the liquid film is quickly evaporated and enters the distillation column.

[0027] A preferred embodiment of the continuous recovery method of hydrazine hydrate is that the internal air pressure of the rectification column is 5-10 kPa, the bottom temperature is 60-70 °C, and the top temperature is 40-50 °C.

[0028] By adopting the above technical solution, hydrazine hydrate remains at the bottom of the rectification column, and most of the water is evaporated to the top of the rectification column and flows out, so as to collect a high-concentration hydrazine hydrate solution.

[0029] A continuous recovery method of hydrazine hydrate uses the above recovery system to recover hydrazine hydrate. The recovery method includes: The residual liquid at the bottom of the wiped film evaporator includes salt and ethylene glycol solution containing hydrazine hydrate. The residual liquid is injected into the receiver. The protective gas supplier passes protective gas into the centrifuge. The receiver stirs the residual liquid. The feeding pump pumps the residual liquid in the receiver into the centrifuge. The centrifuge is started to separate the salt and the ethylene glycol solution by stratification.

[0030] By adopting the above technical solution, the salt and the ethylene glycol solution in the residual liquid are separated, and there is a high concentration of hydrazine hydrate in the residual liquid. Without the protection of isolating air with protective gas, there is a risk of combustion and explosion. Protective gas is introduced during the centrifugation process to avoid the risk of combustion and explosion.

[0031] Compared with the related technology, the continuous recovery system and method of hydrazine hydrate of the present application have the following beneficial effects: 1. An alkali solution is added to the hydrazine hydrate hydrochloride solution in the present application for neutralization. After neutralization, the hydrazine hydrate hydrochloride becomes hydrazine hydrate and sodium chloride salt, and the concentration of hydrazine hydrate is 45-50%. Then ethylene glycol is added. The purpose of adding ethylene glycol is to ensure that the remaining salt has fluidity in the wiped film evaporator after the solution is distilled by the wiped film evaporator and can flow smoothly into the receiver. Due to the high boiling point of ethylene glycol, it will not be evaporated. This can effectively solve the problem of difficult separation between hydrazine hydrate and salt.

[0032] 2. The treatment liquid is preheated by the preheater and continuously fed into the wiped film evaporator. The evaporated gas enters the rectification column for rectification to obtain high-purity hydrazine hydrate for recycling. After rectification in the rectification column, most of the water is evaporated from the top of the rectification column, and high-purity hydrazine hydrate is obtained at the bottom of the column. This method can achieve continuous feeding and discharging, greatly improve the production efficiency, and effectively solve the problems of low content of hydrazine hydrate distilled in the kettle type, long distillation time and high energy consumption.

[0033] 3. During the current batch distillation, there will be a high concentration of hydrazine hydrate in the still residue. When the still residue is centrifuged to separate sodium chloride salt, the high-concentration hydrazine hydrate is prone to the risk of combustion and explosion when it comes into contact with air. This application adopts a continuous process to recover hydrazine hydrate, with a short residence time of the material, reducing the contact time between hydrazine hydrate and air, and effectively improving the safety of recovering hydrazine hydrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of a recovery system for continuously recovering hydrazine hydrate.

[0035] Reference numerals: 1, neutralizer; 2, feed pump; 3, preheater; 4, wiped film evaporator; 5, receiver; 6, charging pump; 7, centrifuge; 8, rectifying column; 9, condenser; 10, water receiving container; 11, hydrazine hydrate receiving container; 12, vacuum pump; 13, waste liquid pipe; 14, alkali liquid pipe; 15, solvent pipe; 16, protective gas supplier. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The technical solutions in the embodiments will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the following embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0037] As Figure 1 shown, the recovery system for continuously recovering hydrazine hydrate includes a neutralizer 1, a feed pump 2, a preheater 3, a wiped film evaporator 4, a solid-liquid separation device, a rectifying column 8, a condenser 9, a water receiving container 10, a hydrazine hydrate receiving container 11, a vacuum pump 12, and also includes a waste liquid pipe 13, an alkali liquid pipe 14 and a solvent pipe 15. The solid-liquid separation device includes a receiver 5 with a stirring mechanism, a charging pump 6, a centrifuge 7 and a protective gas supplier 16.

[0038] The waste liquid pipe 13, the alkali liquid pipe 14 and the solvent pipe 15 are all connected to the neutralizer 1, and can respectively introduce waste liquid containing hydrazine hydrate hydrochloride, 20 - 35% (mass fraction) sodium hydroxide solution and ethylene glycol solvent into the neutralizer 1.

[0039] The neutralizer 1 can be an explosion-proof double-layer glass kettle produced by Gongyi Yuhua Instrument Co., Ltd., with a model of YSF-20L and a volume of 20L. It includes a jacket, a motor, a stirrer, a condenser, a pressure gauge, and a temperature display. The upper end of the neutralizer 1 is provided with a feed inlet and a pH detector is installed. The pH detector is used to detect the pH value of the waste liquid. The lower end of the neutralizer 1 is provided with a discharge port, which is connected to the feed pump 2. The feed pump 2 is connected to the preheater 3, and the preheater 3 is connected to the wiped film evaporator 4.

[0040] The scraping thin-film evaporator 4 mainly consists of a jacket and a scraper. Heat-conducting oil is passed through the jacket. The scraper is installed on a rotating shaft, and the rotating shaft is driven by a motor to rotate. The bottom discharge port of the scraping thin-film evaporator 4 is connected to the receiver 5, and the steam outlet at the upper end of the scraping thin-film evaporator 4 is connected to the feed port in the middle of the rectifying column 8. The scraping thin-film evaporator 4 can be an instrument of model DEA-BM-10 manufactured by Shenzhen Haocheng Instruments Co., Ltd., with an evaporation area of 0.12 m 2 , and the processing capacity is 0.5 - 2.5 kg / h. The scraping thin-film evaporator 4 includes a stirring motor, a sliding scraper, a receiving bottle, a main heater, and a condenser. The evaporation temperature can be set at 90 - 130 °C, the internal air pressure is 5 - 10 kPa, and the feed flow rate is 10 - 20 g / min. The scraping thin-film evaporator 4 is a highly efficient and precise evaporation device. The working principle is that the material is injected tangentially along the inner wall from the upper part of the scraping thin-film evaporator 4. Driven by gravity and the rotating scraper, a downward-spiraling thin film is formed along the inner wall surface of the shell. The scraper is driven by a rotating shaft at the center of the cylinder, and the gap between the scraper and the inner wall of the heating tube is controlled between 0.75 and 1.5 millimeters, so that the raw liquid forms a uniform liquid film under the drive of the rotating scraping blade. The secondary steam generated by the evaporation of the liquid film by heating is introduced into the rectifying column 8, and the concentrated salt-containing material is discharged from the bottom of the scraping thin-film evaporator 4 to the receiver 5.

[0041] The lower end of the receiver 5 is connected to a feeding pump 6 through a pipeline, and the feeding pump 6 is connected to a centrifuge 7 through a pipeline.

[0042] The centrifuge 7 can be a PSB100 type plate centrifuge manufactured by Suzhou Bato Centrifuge Manufacturing Co., Ltd., with a volume of 0.3 L. The centrifuge 7 is connected to a protective gas supplier 16, and the protective gas supplier 16 supplies nitrogen. Centrifugation is carried out under nitrogen protection to avoid the risk of explosion when high-concentration hydrazine hydrate comes into contact with air during centrifugation.

[0043] The internal air pressure of the rectifying column 8 is 5 - 10 kPa, the bottom temperature is 60 - 70 °C, and the top temperature is 40 - 50 °C.

[0044] The bottom of the rectifying column 8 is connected to a hydrazine hydrate receiving container 11. The top of the rectifying column 8 is connected to one side of the upper end of the condenser 9. The vacuum pump 12 is connected to the other side of the upper end of the condenser 9, and the water receiving container 10 is connected to the lower end of the condenser 9. The casing of the condenser 9 passes through cooling water.

[0045] The vacuum pump 12 is connected to the other side of the upper end of the condenser 9, and can create a negative pressure to introduce the steam at the top of the rectifying column 8 into the condenser, where it is cooled into liquid water. The vacuum pump 12 can be a two-stage rotary vane vacuum pump. The pumping speed of this vacuum pump reaches 4 liters per second, and it can achieve a higher vacuum degree, with good stability and low noise.

[0046] Each device in the recovery system is interconnected, and the material is transported between devices by a pump to achieve the continuity of the process and improve efficiency. After rectification in the rectification column, hydrazine hydrate with a high purity of 75-85% (mass concentration) is obtained. The specific process of the recovery method for continuously recovering hydrazine hydrate using this recovery system is as follows: 1. Open the valve at the feed inlet of neutralizer 1, and first add the waste liquid containing hydrazine hydrate hydrochloride solution into neutralizer 1. While stirring, add 30-35% (mass concentration) sodium hydroxide solution to neutralizer 1, for example, 32% (mass concentration) sodium hydroxide solution. When the pH value of the solution in neutralizer 1 is between 10-13, stop adding, and then stir for 1 h. Generally, the concentration of hydrazine hydrate in the solution after neutralization is 45-50%. Add a certain amount of ethylene glycol to the kettle, and the mass ratio of ethylene glycol to the waste liquid is 1:(3.5-5.5), preferably the mass ratio of ethylene glycol to the waste liquid is 1:(4.5-5), for example, 1:4.7, to obtain a treatment liquid. The treatment liquid is fed to preheater 3 by feed pump 2. The set temperature of preheater 3 is 70-90°C, preferably 80-85°C, for example, 80°C, 82°C, 85°C. Turn on vacuum pump 12 to send the treatment liquid into wiped film evaporator 4. Since the boiling point of ethylene glycol is relatively high at 197.3°C and it is not easy to evaporate during wiped film distillation, it can ensure that after the solution passes through wiped film evaporator 4, the remaining sodium chloride salt has fluidity in wiped film evaporator 4 and can flow smoothly into receiver 5, effectively solving the problem of difficult separation between hydrazine hydrate and sodium chloride salt.

[0047] 2. Keep vacuum pump 12 turned on, turn on the jacketed heat transfer oil of preheater 3, turn on the jacketed cooling water of condenser 9, turn on the jacketed heat transfer oil of wiped film evaporator 4, and turn on the stirring motor of wiped film evaporator 4. The evaporation conditions of wiped film evaporator 4 are: the temperature of the heat transfer oil is 90-130°C, for example, 100°C, 110°C, the internal air pressure is 5-10 kPa, for example, 5 kPa, 7 kPa, and the motor speed can be selected as 250 rpm. The hydrazine hydrate solution enters wiped film evaporator 4 from the feed inlet along the tangential direction of the inner wall. Under the action of its own gravity and the scraper, a uniform liquid film is formed. The hydrazine hydrate vapor and water vapor escape from the top and enter rectification column 8 for rectification; the sodium chloride salt and the ethylene glycol solution containing hydrazine hydrate are discharged from the bottom and enter receiver 5.

[0048] 3. After the hydrazine hydrate vapor escapes, it enters the rectifying column 8 and is fed into the middle of the rectifying column 8. The rectifying conditions can be: the bottom temperature is 60 - 70 °C, the top temperature is 40 - 50 °C, and the internal air pressure is 5 - 10 kPa, such as 6 kPa and 8 kPa. The water vapor flowing out from the top of the rectifying column 8 is introduced into the condenser 9, and after condensation, it flows into the water receiving container 10. The cooling water temperature can be 5 °C. The high-concentration hydrazine hydrate solution flows into the hydrazine hydrate receiving container 11 from the bottom of the rectifying column 8. The mass content of hydrazine hydrate in this hydrazine hydrate solution is 80 - 85%, that is, a high-concentration hydrazine hydrate solution is recovered.

[0049] 4. Start the centrifuge 7, open the nitrogen pipeline valve on the centrifuge, and carry out centrifugation under nitrogen protection. The ethylene glycol solution containing sodium chloride salt in the receiver 5 is transported to the centrifuge 7 through the feeding pump 6. Under the action of centrifugal force, the sodium chloride salt and the ethylene glycol solution are separated. After the sodium chloride salt is dried, it is recovered. Since the ethylene glycol solution contains 3 - 5% of hydrazine hydrate, the ethylene glycol solution is recovered and used for the treatment of the next batch of hydrazine hydrate hydrochloride.

[0050] The continuous recovery system and recovery method for hydrazine hydrate in the above embodiments have the following advantages: First, neutralize the hydrazine hydrate hydrochloride solution to generate hydrazine hydrate and sodium chloride salt, and then add ethylene glycol. Ethylene glycol can disperse the salts in the system, making the salts have fluidity in the wiped film evaporator 4 and can smoothly flow into the receiver 5. And due to the high boiling point of ethylene glycol, according to the parameters of the recovery method, it will not be evaporated, effectively solving the problem of difficult separation between hydrazine hydrate and salts.

[0051] This method can achieve continuous feeding and discharging, greatly improving production efficiency, and effectively solving the problems of low hydrazine hydrate content in kettle-distilled water, long distillation time, and high energy consumption.

[0052] Using a continuous process to recover hydrazine hydrate, the residence time of the material is short, reducing the contact time between hydrazine hydrate and air, and effectively improving the safety of recovering hydrazine hydrate.

[0053] Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A recovery system for continuously recovering hydrazine hydrate, characterized in that: It comprises a waste liquid pipe (13), an alkali liquid pipe (14), a solvent pipe (15), a neutralizer (1), a preheater (3), a scraper film evaporator (4), a solid-liquid separation device, a distillation tower (8) and a hydrazine hydrate receiving container (11); The waste liquid pipe (13), the alkali liquid pipe (14) and the solvent pipe (15) are respectively connected to the neutralizer (1); the neutralizer (1) is connected to the preheater (3); the preheater (3) is connected to the scraper film evaporator (4); the lower end of the scraper film evaporator (4) is connected to the solid-liquid separation device, and the upper end is connected to the middle of the distillation tower (8); the lower end of the distillation tower (8) is connected to the hydrazine hydrate receiving container (11).

2. The recovery system for continuously recovering hydrazine hydrate according to claim 1, characterized in that: The solid-liquid separation device comprises a receiver (5) with a stirring mechanism, a feed pump (6), a centrifuge (7) and a protective gas supplier (16); the receiver (5) is connected to the lower end of the scraper film evaporator (4); the feed pump (6) is connected to the receiver (5) and the centrifuge (7); and the protective gas supplier (16) is connected to the centrifuge (7).

3. The recovery system for continuously recovering hydrazine hydrate according to claim 1 or 2, characterized in that: The recovery system further comprises a condenser (9), a water receiving container (10) and a vacuum pump (12); the upper end of the distillation tower (8) is connected to one side of the upper end of the condenser (9); the vacuum pump (12) is connected to the other side of the upper end of the condenser (9); and the water receiving container (10) is connected to the lower end of the condenser (9).

4. The continuous recovery system for hydrazine hydrate according to claim 1, characterized in that: The neutralizer (1) is equipped with an agitator and a pH detector.

5. A method for continuously recovering hydrazine hydrate, characterized in that: The recovery system of claim 3 is used to recover hydrazine hydrate; the recovery method comprises: adding waste liquid containing hydrazine hydrate hydrochloride into the neutralizer (1) through the waste liquid pipe (13), adding alkali liquid into the neutralizer (1) through the alkali liquid pipe (14), so that the pH value of the waste liquid in the neutralizer (1) is between 10 and 13; adding ethylene glycol into the neutralizer (1) through the solvent pipe (15) to obtain a treated liquid; Passing the treated liquid in the neutralizer (1) into the preheater (3) for preheating; Turning on the vacuum pump (12) to evacuate the condenser (9), the distillation tower (8) and the scraped film evaporator (4); The preheated treatment liquid is passed into the scraped film evaporator (4), and the scraped film evaporator (4) performs scraping treatment and heating on the treatment liquid, so that hydrazine hydrate and water in the treatment liquid evaporate and enter the distillation tower (8), and ethylene glycol does not evaporate; the residual liquid of the treatment liquid enters the solid-liquid separation device; The distillation tower (8) distills the mixed vapor of hydrazine hydrate and water entering the distillation tower, so that the water vapor flows out from the top and the hydrazine hydrate condenses and enters the hydrazine hydrate receiving container (11).

6. The method for continuously recovering hydrazine hydrate according to claim 5, characterized in that: The mass ratio of the ethylene glycol to the waste liquid is 1:(3.5-5.5).

7. The method for continuously recovering hydrazine hydrate according to claim 5, characterized in that: The preheater (3) is heated to 70-90°C.

8. The method for continuously recovering hydrazine hydrate according to claim 5, characterized in that: The temperature of the scraped thin film evaporator (4) is 90-130°C, and the internal pressure is 5-10 kPa.

9. The method for continuously recovering hydrazine hydrate according to claim 5, characterized in that: The internal gas pressure of the distillation tower (8) is 5-10 kPa, the bottom temperature is 60-70°C, and the top temperature is 40-50°C.

10. A method for continuously recovering hydrazine hydrate, characterized in that: The recovery system of claim 2 is used to recover hydrazine hydrate; the recovery method comprises: The residual liquid at the bottom of the scraped film evaporator (4) includes salt and an ethylene glycol solution containing hydrazine hydrate. The residual liquid is injected into the receiver (5). The protective gas supplier (16) introduces protective gas into the centrifuge (7). The receiver (5) stirs the residual liquid. The feed pump (6) pumps the residual liquid in the receiver (5) into the centrifuge (7). The centrifuge (7) is started to separate the salt and the ethylene glycol solution into layers.

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