Method and device for recovering hydrazine hydrate

Abstract

The invention discloses a method and a device for recovering hydrazine hydrate, and processes of feeding distillation, condensation water separation and cyclic collection are carried out by virtue of a system device consisting of a reduced pressure rectification mechanism, a condensation water separation mechanism and a cyclic collection mechanism. The hydrazine hydrate is prevented from being decomposed and exploded at high temperature through low-temperature reduced-pressure rectification, and the process safety is remarkably improved; by introducing the layered toluene into the rectifying tower, the hydrazine hydrate entrainment in the distilled liquid is reduced, the hydrazine hydrate residual quantity in the layered wastewater is further reduced and is reduced by more than 80% compared with a traditional method, and the hydrazine hydrate recovery rate is remarkably improved; the water distribution mechanism automatically separates methylbenzene and wastewater, and the automation degree is high; the layered toluene is recycled, the raw material cost is reduced, the wastewater is directly discharged after reaching the standard, the subsequent sewage treatment cost is reduced, and the method is more economical and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrazine hydrate recovery and utilization, and more particularly to a method and device for recovering hydrazine hydrate. Background Art

[0002] Prothioconazole is a triazolethione fungicide primarily used to control numerous diseases in crops such as cereals, wheat, and legumes. Hydrazine compounds, the intermediates of prothioconazole, are primarily synthesized using the hydrazine hydrate method and the triazole method. Due to the harsh process conditions, low yield, and relatively poor product quality of the triazole method, the hydrazine hydrate method is the most widely used process both domestically and internationally.

[0003] Hydrazine hydrate (N2H4H20), also known as hydrated hydrazine, is strongly alkaline and hygroscopic. Under normal pressure, hydrazine forms an azeotropic mixture with water, and liquid hydrazine hydrate exists as a dimer. It is a core raw material in the synthesis of prothioconazole. However, under current conditions, hydrazine hydrate can only be used in excess for synthesis, resulting in a large amount of low-concentration hydrazine hydrate remaining in the system after the reaction. If discharged directly, its high chemical oxygen demand (COD) would place a severe burden on wastewater treatment systems. The current mainstream recovery method is vacuum distillation, but it has the following drawbacks:

[0004] (1) Poor safety. Hydrazine hydrate easily decomposes at high temperatures to produce gases such as NH3 and N2, and there is a risk of explosion when concentrated to a certain concentration;

[0005] (2) Low efficiency. Hydrazine hydrate is easily entrained by water vapor during the distillation process, resulting in a high concentration of hydrazine hydrate in the distillate, which cannot meet the discharge standards.

[0006] (3) Insufficient stability, process fluctuations can easily cause hydrazine decomposition, affecting the recovery purity. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the object of the present invention is to provide a method and apparatus for recovering hydrazine hydrate to solve one or more of the above problems.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A device for recovering hydrazine hydrate, comprising

[0010] A vacuum distillation mechanism for performing vacuum distillation on low-concentration hydrazine hydrate and toluene;

[0011] The condensation and water separation mechanism is connected to the vacuum distillation mechanism to condense, liquefy and separate the gas phase after distillation;

[0012] The circulation collection mechanism is connected to the condensation and water separation mechanism to classify and receive the stratified objects. The classified different objects are introduced into the vacuum distillation mechanism or discharged after meeting the standards.

[0013] Furthermore, the vacuum distillation mechanism includes a distillation kettle and a distillation tower connected in sequence. The distillation kettle and the distillation tower are both made of stainless steel, and the tower height and tower diameter of the distillation tower are not unique.

[0014] Furthermore, the condensation water separation mechanism includes

[0015] a main condenser connected to a distillation column;

[0016] A vacuum condenser is connected to the circulation collection mechanism through a balance pipe with an on-off valve and is externally connected to a vacuum pipeline;

[0017] a pressure reducer, which is connected to the main condenser and the vacuum condenser at the same time and is also connected to the liquid separator;

[0018] The liquid distributor is connected to the pressure reducer and the circulation collection mechanism.

[0019] Furthermore, the recycling collection mechanism includes

[0020] A toluene storage tank connected to a recovery pipe and equipped with a corresponding valve;

[0021] The wastewater storage tank is connected to the liquid separator through a discharge pipe with a regulating valve, and is also connected to a vacuum condenser and an external discharge pipeline.

[0022] Further, the toluene storage tank is connected to the distillation tower via a recovery pump;

[0023] An interface meter is provided in the liquid distributor and is electrically connected to the regulating valve.

[0024] The recovery method based on the above device has the following steps:

[0025] S1, feeding and distillation, adding low concentration hydrazine hydrate and toluene into the distillation kettle in sequence, and performing vacuum distillation using a distillation tower;

[0026] S2, condensation and water separation, the gas phase of toluene and water distilled under reduced pressure in step S1 is liquefied by means of a main condenser and then enters a liquid separator through a pressure reducer, and toluene and wastewater are automatically separated by density difference;

[0027] S3, circulation and collection, collecting the toluene separated from the layer in step S2 into a toluene storage tank, and sending it back to the top of the distillation tower by a recovery pump;

[0028] The wastewater separated by stratification in step S2 is collected into a wastewater storage tank, and the hydrazine hydrate concentration in the wastewater is tested. If the concentration meets the standard, the wastewater is directly discharged into the sewage treatment system through the drainage pipe.

[0029] Furthermore, the conditions for the reduced pressure distillation in step S1 are a pressure of -0.05 to -0.1 MPa and a temperature ≤ 80°C.

[0030] Furthermore, the toluene separated from the distillation column in step S3 is sent back to the top of the distillation tower to suppress the entrainment of hydrazine hydrate by water vapor through extractive distillation, thereby improving the recovery rate of hydrazine hydrate; the toluene circulating back to the distillation kettle can gradually increase the concentration of hydrazine hydrate.

[0031] Furthermore, the residual hydrazine hydrate content in the wastewater in step S3 is less than 0.01% w / w, which is considered to be up to standard.

[0032] Furthermore, in step S2, a vacuum pipeline and a vacuum condenser are introduced to maintain a vacuum state and assist the progress of hydrocondensation, and a balance pipe is used to maintain the internal pressure.

[0033] In summary, the present invention has the following beneficial effects: decomposition and explosion of hydrazine hydrate at high temperature is avoided by low-temperature vacuum distillation, thereby significantly improving process safety; by introducing toluene after stratification into a distillation tower, the entrainment of hydrazine hydrate in the distillate is reduced, and the residual amount of hydrazine hydrate in the stratified wastewater is further reduced by more than 80% compared with the traditional method, and the hydrazine hydrate recovery rate is significantly improved; the water separation mechanism automatically separates toluene and wastewater, and the degree of automation is high; the stratified toluene is recycled, thereby reducing the cost of raw materials; the wastewater is directly discharged after meeting the standards, thereby reducing the subsequent sewage treatment cost, and is more economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram of an embodiment of the present invention;

[0035] Figure 2 A process flow chart of an embodiment of the present invention.

[0036] In the figure: 1. Distillation kettle; 2. Distillation tower; 3. Main condenser; 4. Vacuum condenser; 5. Equalizing pipe; 6. Vacuum pipeline; 7. Pressure reducer; 8. Liquid separator; 9. Recovery pipe; 10. Toluene storage tank; 11. Wastewater storage tank; 12. Recovery pump; 13. Interface meter; 14. Control valve; 15. Liquid discharge pipe; 1-1. Bottom valve; 1-2. Stratification sight glass; 1-3. Stratification manual valve. DETAILED DESCRIPTION

[0037] Example 1:

[0038] The following is combined with Figure 1-2 The present invention is described in further detail.

[0039] A device for recovering hydrazine hydrate, such as Figure 1 As shown, it is mainly composed of a vacuum distillation mechanism, a condensation water separation mechanism and a circulation collection mechanism connected in sequence, which sequentially carry out vacuum distillation of low-concentration hydrazine hydrate wastewater, liquefaction and stratification of the gas phase after distillation, classified reception of objects after stratification, recycling and harmless waste discharge.

[0040] The vacuum distillation mechanism consists of a connected distillation kettle 1 and distillation tower 2. The specifications of these two towers are determined based on actual production needs. Both are made of stainless steel. The distillation kettle has a volume of 3000L, and the diameter and height of distillation tower 2 are DN800 x H3000mm (tangent-tangent). The tower body and internals are made of SS316L, and the packing is CY700 wire mesh packing (SS316L), with an H_packing of 2500mm.

[0041] The condensation and water separation mechanism includes a main condenser 3 and a vacuum condenser 4, as well as a matching pressure reducer 7 and a liquid separator 8. The main condenser 3 is connected to the distillation tower 2, and the vacuum condenser 4 is connected to the external vacuum pipeline 6. Both condensers are connected to the pressure reducer 7 at the end; the liquid separator 8 is directly connected to the pressure reducer 7, and the liquid separator 8 is also connected to the wastewater storage tank 11 of the circulation collection mechanism.

[0042] The recycling and collection mechanism includes a toluene storage tank 10 and a wastewater storage tank 11. The wastewater storage tank 11 is connected to the piping system of the vacuum condenser 4 via a balance pipe 5 with a valve. The recovery pipe 9 is connected to the toluene storage tank 10 via a pipeline with an on-off valve. The toluene storage tank 10 is connected to the distillation tower 2 via a recovery pump 12. The wastewater storage tank 11 is connected to the liquid separator 8 via a discharge pipe 15 with a regulating valve 14. The wastewater storage tank 11 is also connected to an external drainage pipeline. An interface meter 13 is provided in the liquid separator 8. The interface meter 13 is electrically connected to the regulating valve 14. The interface meter 13 guides the operation of the regulating valve 14 based on relevant parameters inside the liquid separator 8.

[0043] Rectifier 1 is fed from the outside and subsequently receives toluene returned from distillation tower 2. Rectifier 2 purifies the mixture of toluene, water, and hydrazine hydrate distilled from distillation tower 1 and subsequently returns toluene from toluene storage tank 10 via recovery pump 12. Toluene storage tank 10 receives and stores the separated toluene via recovery pipe 9. The vapor phase from distillation tower 2, distilled under reduced pressure, enters main condenser 3. With the assistance of vacuum condenser 4, the entire system remains in a vacuum state. The liquefied phase is introduced into pressure reducer 7 and directly into liquid separator 8, where the toluene and waste liquid of different densities are separated. The waste liquid enters wastewater storage tank 11, and the toluene enters recovery pipe 9.

[0044] The hydrazine hydrate recovery method completed using the above-mentioned device is as follows: Figure 2 As shown, the steps are as follows,

[0045] S1, feeding and distillation, 2000kg of low-concentration 30% hydrazine hydrate and 500kg of toluene are sequentially added to the distillation kettle 1, and vacuum distillation is performed using the distillation tower 2;

[0046] The conditions for the reduced pressure distillation in step S1 are a pressure of -0.07 MPa and a temperature of 60-80°C.

[0047] S2, condensation and water separation, the toluene, water and trace hydrazine hydrate gas phase distilled under reduced pressure in step S1 are liquefied by means of the main condenser 3 and then enter the liquid separator 8 through the pressure reducer 7, and the toluene and wastewater are automatically separated by density difference;

[0048] In step S2 , a vacuum line 6 and a vacuum condenser 4 are introduced to maintain a vacuum state and assist the progress of hydrocondensation, and the internal pressure is maintained with the help of a balance pipe 5 .

[0049] S3, circulation and collection, collecting the toluene separated from the distillation column in step S2 into a toluene storage tank 10, and sending the toluene back to the top of the distillation column 2 by a recovery pump 12;

[0050] The toluene separated from the distillation column in step S3 is sent back to the top of the distillation column 2 to suppress the entrainment of hydrazine hydrate by water vapor through extractive distillation, thereby improving the recovery rate of hydrazine hydrate; the toluene circulating back to the distillation kettle 1 can gradually increase the hydrazine hydrate concentration to 64%;

[0051] Stop distillation, and separate the lower layer of 64% concentration of hydrazine hydrate through the bottom valve 1-1, the layering sight glass 1-2 and the layering hand valve 1-3 at the bottom of the reactor 1, and the upper toluene layer is recycled to the next stage. Specifically, when the hydrazine hydrate reaches the target concentration, open the bottom valve 1-1, adjust the opening of the layering hand valve 1-3, observe the layering interface through the layering sight glass 1-2, separate the lower layer of high concentration hydrazine hydrate, and close the bottom valve 1-1 after the layering is completed, and the upper toluene layer remains in the reactor for reuse.

[0052] The wastewater separated from the stratification in step S2 is collected into the wastewater storage tank 11, and the hydrazine hydrate concentration in the wastewater is tested. If the concentration meets the standard, it is directly discharged into the sewage treatment system through the drainage pipe;

[0053] The residual hydrazine hydrate content in the wastewater in step S3 is less than 0.01% w / w, which is considered to be up to standard.

[0054] Example 2:

[0055] A device for recovering hydrazine hydrate, such as Figure 1 As shown, it is mainly composed of a vacuum distillation mechanism, a condensation water separation mechanism and a circulation collection mechanism connected in sequence, which sequentially carry out vacuum distillation of low-concentration hydrazine hydrate wastewater, liquefaction and stratification of the gas phase after distillation, classified reception of objects after stratification, recycling and harmless waste discharge.

[0056] The vacuum distillation mechanism consists of a connected distillation kettle 1 and a distillation tower 2. The specifications of these two towers are determined based on actual production needs. Both are made of stainless steel. The distillation kettle has a volume of 3000L, and the diameter and height of distillation tower 2 are DN800 x H4000mm (tangent-tangent). The tower body and internals are made of SS316L, and the packing is CY700 wire mesh packing (SS316L), with an H_packing of 3500mm.

[0057] The condensation and water separation mechanism includes a main condenser 3 and a vacuum condenser 4, as well as a matching pressure reducer 7 and a liquid separator 8. The main condenser 3 is connected to the distillation tower 2, and the vacuum condenser 4 is connected to the external vacuum pipeline 6. Both condensers are connected to the pressure reducer 7 at the end; the liquid separator 8 is directly connected to the pressure reducer 7, and the liquid separator 8 is also connected to the wastewater storage tank 11 of the circulation collection mechanism.

[0058] The circulation collection mechanism includes a toluene storage tank 10 and a wastewater storage tank 11. The wastewater storage tank 11 is connected to the piping system of the vacuum condenser 4 through a balance pipe 5 with a valve. The recovery pipe 9 is connected to the toluene storage tank 10 through a pipeline with an on-off valve and is specially provided with a corresponding valve. The toluene storage tank 10 is also connected to the distillation tower 2 through a recovery pump 12. The wastewater storage tank 11 is connected to the liquid separator 8 through a discharge pipe 15 with a regulating valve 14. The wastewater storage tank 11 is also connected to an external drainage pipeline. An interface meter 13 is provided in the liquid separator 8. The interface meter 13 is electrically connected to the regulating valve 14. The interface meter 13 guides the operation of the regulating valve 14 through relevant parameters inside the liquid separator 8.

[0059] Rectifier 1 is fed from the outside and subsequently receives toluene returned from distillation tower 2. Rectifier 2 purifies the mixture of toluene, water, and hydrazine hydrate distilled from distillation tower 1 and subsequently returns toluene from toluene storage tank 10 via recovery pump 12. Toluene storage tank 10 receives and stores the separated toluene via recovery pipe 9. The vapor phase from distillation tower 2, distilled under reduced pressure, enters main condenser 3. With the assistance of vacuum condenser 4, the entire system remains in a vacuum state. The liquefied phase is introduced into pressure reducer 7 and directly into liquid separator 8, where the toluene and waste liquid of different densities are separated. The waste liquid enters wastewater storage tank 11, and the toluene enters recovery pipe 9.

[0060] The hydrazine hydrate recovery method completed using the above-mentioned device is as follows: Figure 2 As shown, the steps are as follows,

[0061] S1, feeding and distillation, 2000kg of low-concentration 30% hydrazine hydrate and 500kg of toluene are sequentially added to the distillation kettle 1, and vacuum distillation is performed using the distillation tower 2;

[0062] The conditions for the reduced pressure distillation in step S1 are a pressure of -0.07 MPa and a temperature of 60-80°C.

[0063] S2, condensation and water separation, the toluene, water and trace hydrazine hydrate gas phase distilled under reduced pressure in step S1 are liquefied by means of the main condenser 3 and then enter the liquid separator 8 through the pressure reducer 7, and the toluene and wastewater are automatically separated by density difference;

[0064] In step S2 , a vacuum line 6 and a vacuum condenser 4 are introduced to maintain a vacuum state and assist the progress of hydrocondensation, and the internal pressure is maintained with the help of a balance pipe 5 .

[0065] S3, circulation and collection, collecting the toluene separated from the distillation column in step S2 into a toluene storage tank 10, and sending the toluene back to the top of the distillation column 2 by a recovery pump 12;

[0066] The toluene separated from the distillation column in step S3 is sent back to the top of the distillation column 2 to suppress the entrainment of hydrazine hydrate by water vapor through extractive distillation, thereby improving the recovery rate of hydrazine hydrate; the toluene circulating back to the distillation kettle 1 can gradually increase the hydrazine hydrate concentration to 75%;

[0067] After distillation is stopped, reactor 1 separates the lower layer of hydrazine hydrate (75% concentration) via bottom valve 1-1, separation sight glass 1-2, and separation hand valve 1-3. The upper toluene layer is recycled to the next stage. Specifically, when the hydrazine hydrate reaches the target concentration, bottom valve 1-1 is opened, the opening of separation hand valve 1-3 is adjusted, and the separation interface is observed through separation sight glass 1-2 to separate the lower, high-concentration hydrazine hydrate layer. After separation is complete, bottom valve 1-1 is closed, and the upper toluene layer remains in the reactor for reuse.

[0068] The wastewater separated from the stratification in step S2 is collected into the wastewater storage tank 11, and the hydrazine hydrate concentration in the wastewater is tested. If the concentration meets the standard, it is directly discharged into the sewage treatment system through the drainage pipe;

[0069] The residual hydrazine hydrate content in the wastewater in step S3 is less than 0.01% w / w, which is considered to be up to standard.

[0070] Example 3:

[0071] A device for recovering hydrazine hydrate, such as Figure 1 As shown, it is mainly composed of a vacuum distillation mechanism, a condensation water separation mechanism and a circulation collection mechanism connected in sequence, which sequentially carry out vacuum distillation of low-concentration hydrazine hydrate wastewater, liquefaction and stratification of the gas phase after distillation, classified reception of objects after stratification, recycling and harmless waste discharge.

[0072] The vacuum distillation mechanism consists of a connected distillation kettle 1 and a distillation tower 2. The specifications of these two towers are determined based on actual production needs. Both are made of stainless steel. The distillation kettle has a volume of 3000L, and the diameter and height of distillation tower 2 are DN800 x H4000mm (tangent-tangent). The tower body and internals are made of SS316L, and the packing is CY700 wire mesh packing (SS316L), with an H_packing of 3500mm.

[0073] The condensation and water separation mechanism includes a main condenser 3 and a vacuum condenser 4, as well as a matching pressure reducer 7 and a liquid separator 8. The main condenser 3 is connected to the distillation tower 2, and the vacuum condenser 4 is connected to the external vacuum pipeline 6. Both condensers are connected to the pressure reducer 7 at the end; the liquid separator 8 is directly connected to the pressure reducer 7, and the liquid separator 8 is also connected to the wastewater storage tank 11 of the circulation collection mechanism.

[0074] The circulation collection mechanism includes a toluene storage tank 10 and a wastewater storage tank 11. The wastewater storage tank 11 is connected to the piping system of the vacuum condenser 4 through a balance pipe 5 with a valve. The recovery pipe 9 is connected to the toluene storage tank 10 through a pipeline with an on-off valve and is specially provided with a corresponding valve. The toluene storage tank 10 is also connected to the distillation tower 2 through a recovery pump 12. The wastewater storage tank 11 is connected to the liquid separator 8 through a discharge pipe 15 with a regulating valve 14. The wastewater storage tank 11 is also connected to an external drainage pipeline. An interface meter 13 is provided in the liquid separator 8. The interface meter 13 is electrically connected to the regulating valve 14. The interface meter 13 guides the operation of the regulating valve 14 through relevant parameters inside the liquid separator 8.

[0075] Rectifier 1 is fed from the outside and subsequently receives toluene returned from distillation tower 2. Rectifier 2 purifies the mixture of toluene, water, and hydrazine hydrate distilled from distillation tower 1 and subsequently returns toluene from toluene storage tank 10 via recovery pump 12. Toluene storage tank 10 receives and stores the separated toluene via recovery pipe 9. The vapor phase from distillation tower 2, distilled under reduced pressure, enters main condenser 3. With the assistance of vacuum condenser 4, the entire system remains in a vacuum state. The liquefied phase is introduced into pressure reducer 7 and directly into liquid separator 8, where the toluene and waste liquid of different densities are separated. The waste liquid enters wastewater storage tank 11, and the toluene enters recovery pipe 9.

[0076] The hydrazine hydrate recovery method completed using the above-mentioned device is as follows: Figure 2 As shown, the steps are as follows,

[0077] S1, feeding and distillation, 2000kg of low-concentration 45% hydrazine hydrate and 500kg of toluene are sequentially added to the distillation kettle 1, and vacuum distillation is performed using the distillation tower 2;

[0078] The conditions for the reduced pressure distillation in step S1 are a pressure of -0.08 MPa and a temperature of 60-80°C.

[0079] S2, condensation and water separation, the toluene, water and trace hydrazine hydrate gas phase distilled under reduced pressure in step S1 are liquefied by means of the main condenser 3 and then enter the liquid separator 8 through the pressure reducer 7, and the toluene and wastewater are automatically separated by density difference;

[0080] In step S2 , a vacuum line 6 and a vacuum condenser 4 are introduced to maintain a vacuum state and assist the progress of hydrocondensation, and the internal pressure is maintained with the help of a balance pipe 5 .

[0081] S3, circulation and collection, collecting the toluene separated from the distillation column in step S2 into a toluene storage tank 10, and sending the toluene back to the top of the distillation column 2 by a recovery pump 12;

[0082] The toluene separated from the distillation column in step S3 is sent back to the top of the distillation column 2 to suppress the entrainment of hydrazine hydrate by water vapor through extractive distillation, thereby improving the recovery rate of hydrazine hydrate; the toluene circulating back to the distillation kettle 1 can gradually increase the hydrazine hydrate concentration to 80%;

[0083] Stop distillation, and separate the lower layer of hydrazine hydrate with a concentration of 80% through the bottom valve 1-1, the layering sight glass 1-2 and the layering hand valve 1-3 at the bottom of the reactor 1, and the upper toluene layer is recycled to the next stage. Specifically, when the hydrazine hydrate reaches the target concentration, open the bottom valve 1-1, adjust the opening of the layering hand valve 1-3, observe the layering interface through the layering sight glass 1-2, separate the lower layer of high-concentration hydrazine hydrate, and close the bottom valve 1-1 after the layering is completed, and the upper toluene layer remains in the reactor for reuse.

[0084] The wastewater separated from the stratification in step S2 is collected into the wastewater storage tank 11, and the hydrazine hydrate concentration in the wastewater is tested. If the concentration meets the standard, it is directly discharged into the sewage treatment system through the drainage pipe;

[0085] The residual hydrazine hydrate content in the wastewater in step S3 is less than 0.01% w / w, which is considered to be up to standard.

[0086] Example 4

[0087] The selected batch of prothioconazole synthetic wastewater is fed to the 3000L distillation kettle 1, which contains 20% hydrazine hydrate concentration and weighs 2000kg, and then 500kg toluene is pumped in. The diameter and height of the distillation tower 2 are DN800×H3000mm (tangent-tangent), the tower body and internal parts are made of SS316L, the filler is CY700 wire mesh filler (SS316L), and H_packing is 2500mm. Start the decompression system and pass through the distillation tower 2 again under a pressure of -0.08MPa and a temperature of 75℃. The distilled gas phase enters the water separator after condensation, and the density is 0.87g / cm 3 of toluene and a density of 1 g / cm 3 The water is automatically separated, and the toluene is pumped back to the top of distillation tower 2 via toluene storage tank 10. The wastewater is discharged after testing for a hydrazine content of no more than 0.01%. After 6 hours of continuous distillation, the hydrazine hydrate concentration in the kettle reaches 75%. The process is stopped, cooled, and separated. The hydrazine hydrate is recovered and reused in the synthesis process of the prothioconazole hydrazine compound. The toluene in the kettle is retained for the next batch of hydrazine hydrate concentration.

[0088] By optimizing the distillation process and water separation mechanism, the low hydrazine hydrate recovery efficiency, poor safety, and high residual wastewater issues of existing technologies are addressed. By using toluene reflux to continuously reduce the water content in the system, the hydrazine hydrate concentration in distillation reactor 1 is gradually increased to 64% to 80%. This produces high-concentration hydrazine hydrate that can be directly applied to the synthesis of prothioconazole-hydrazine compounds. The single-batch hydrazine hydrate recovery rate exceeds 95%, and wastewater treatment costs are reduced by 60%, resulting in significant economic and environmental benefits.

[0089] It should be noted that this specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A device for recovering hydrazine hydrate, characterized in that: include A vacuum distillation mechanism for performing vacuum distillation on low-concentration hydrazine hydrate and toluene; The condensation and water separation mechanism is connected to the vacuum distillation mechanism to condense, liquefy and separate the gas phase after distillation; The circulation collection mechanism is connected to the condensation and water separation mechanism to classify and receive the stratified objects. The classified different objects are introduced into the vacuum distillation mechanism or discharged after meeting the standards.

2. The device for recovering hydrazine hydrate according to claim 1, wherein: The vacuum distillation mechanism includes a distillation kettle and a distillation tower connected in sequence. The distillation kettle and the distillation tower are both made of stainless steel. The tower height and tower diameter of the distillation tower are not unique.

3. The device for recovering hydrazine hydrate according to claim 2, wherein: Condensate water distribution mechanism includes a main condenser connected to a distillation column; A vacuum condenser is connected to the circulation collection mechanism through a balance pipe with an on-off valve and is externally connected to a vacuum pipeline; a pressure reducer, which is connected to the main condenser and the vacuum condenser at the same time and is also connected to the liquid separator; The liquid distributor is connected to the pressure reducer and the circulation collection mechanism.

4. The device for recovering hydrazine hydrate according to claim 3, wherein: Recycling collection agencies include A toluene storage tank connected to a recovery pipe and equipped with a corresponding valve; The wastewater storage tank is connected to the liquid separator through a discharge pipe with a regulating valve, and is also connected to a vacuum condenser and an external discharge pipeline.

5. The device for recovering hydrazine hydrate according to claim 4, wherein: The toluene storage tank is connected to the distillation column via a recovery pump; An interface meter is provided in the liquid distributor and is electrically connected to the regulating valve.

6. A method for recovering hydrazine hydrate, characterized in that: The device for recovering hydrazine hydrate according to claim 5 is used, and the steps are as follows: S1, feeding and distillation, adding low concentration hydrazine hydrate and toluene into the distillation kettle in sequence, and performing vacuum distillation using a distillation tower; S2, condensation and water separation, the gas phase of toluene and water distilled under reduced pressure in step S1 is liquefied by means of a main condenser and then enters a liquid separator through a pressure reducer, and toluene and wastewater are automatically separated by density difference; S3, circulation and collection, collecting the toluene separated from the layer in step S2 into a toluene storage tank, and sending it back to the top of the distillation tower by a recovery pump; The wastewater separated by stratification in step S2 is collected into a wastewater storage tank, and the hydrazine hydrate concentration in the wastewater is tested. If the concentration meets the standard, the wastewater is directly discharged into the sewage treatment system through the drainage pipe.

7. The method for recovering hydrazine hydrate according to claim 6, wherein: The conditions for the reduced pressure distillation in step S1 are a pressure of -0.05 to -0.1 MPa and a temperature of ≤80°C.

8. The method for recovering hydrazine hydrate according to claim 6, wherein: The toluene separated from the distillation column in step S3 is sent back to the top of the distillation tower to suppress the entrainment of hydrazine hydrate by water vapor through extractive distillation, thereby improving the recovery rate of hydrazine hydrate; the toluene circulating back to the distillation kettle can gradually increase the concentration of hydrazine hydrate.

9. The method for recovering hydrazine hydrate according to claim 6, wherein: The residual hydrazine hydrate content in the wastewater in step S3 is less than 0.01% w / w, which is considered to be up to standard.

10. The method for recovering hydrazine hydrate according to claim 6, wherein: In step S2, a vacuum pipeline and a vacuum condenser are introduced to maintain a vacuum state and assist the progress of hydrocondensation, and the internal pressure is maintained with the help of a balance pipe.

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