A method and apparatus for recycling hydrazine hydrate

Abstract

The application specifically discloses a method for recycling hydrazine hydrate, which comprises the steps of primary neutralization, hydrazine removal, secondary neutralization and separation and purification, etc. The hydrazine hydrate mother liquor containing impurities such as hydrazinium chloride and organic matters is first neutralized by sodium hydroxide, and the hydrazinium chloride is converted into hydrazine hydrate. After the hydrazine hydrate in the waste water is dissociated into gaseous hydrazine and then penetrates through a hydrazine removal module into sulfuric acid absorbing solution, the hydrazine hydrate is converted into hydrazinium sulfate. The hydrazinium sulfate is precipitated after cooling, and then is filtered and subjected to secondary neutralization with a sodium hydroxide solution, so as to be reconverted into a high-concentration hydrazine hydrate mixture. The hydrazine hydrate mixture is subjected to evaporation and condensation to obtain a hydrazine hydrate product. The hydrazine hydrate product has high purity and high yield, and has a relatively broad industrialization prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrazine hydrate recycling, more specifically, it relates to a method and device for recycling hydrazine hydrate. BACKGROUND

[0002] Pyrazole acid is a key intermediate for the production of chlorantraniliprole, and pyrazole acid is usually obtained by using hydrazine substitute and maleate as raw materials, and through a series of reactions such as ring formation, halogenation, oxidation and ester hydrolysis. The hydrazine substitute is generally 3-chloro-2-hydrazinylpyridine, which is synthesized from hydrazine hydrate and 2,3-dichloropyridine. A large amount of hydrazine hydrate is used in the preparation process, and hydrogen chloride is released during the reaction. Hydrogen chloride is neutralized with hydrazine hydrate to obtain hydrazine hydrochloride. Therefore, the mother liquor contains a large amount of hydrazine hydrochloride and excess hydrazine hydrate, and the hydrazine content is about 30-40wt% of the mother liquor, which has great recycling value. At the same time, the mother liquor is rich in organic matter, and the chemical oxygen demand reaches more than ten thousand, which is difficult to directly enter the sewage station for treatment, and the treatment cost is high. Based on the above characteristics, it is necessary to effectively recycle the hydrazine hydrate in the hydrazine-containing mother liquor.

[0003] At present, there are several recycling technologies related to hydrazine hydrate as follows:

[0004] CN113716535A discloses a method and device for recycling hydrazine hydrate in the preparation process of 3-chloro-2-hydrazinylpyridine intermediate. In this method, hydrazine hydrochloride is first converted into sodium chloride, which is precipitated by cooling, and the filtrate is evaporated to recover hydrazine hydrate. However, in this method, the organic matter in the mother liquor is also easily evaporated with hydrazine hydrate, reducing the purity of hydrazine hydrate and affecting the subsequent recycling of hydrazine hydrate.

[0005] CN1172862A discloses a method for treating and recycling phenylhydrazine wastewater. In this method, macroporous adsorption resin is used to absorb phenylhydrazine in the wastewater, and then a desorption agent is used to desorb the phenylhydrazine in the macroporous adsorption resin. The applicant tried to use this technical solution to treat the hydrazine-containing mother liquor produced in the production of 3-chloro-2-hydrazinylpyridine, and found that part of the organic matter was desorbed together with the hydrazine hydrate, affecting the purity of the hydrazine hydrate. SUMMARY

[0006] The present application provides a method and device for recycling hydrazine hydrate, which recovers high-purity hydrazine hydrate product from the hydrazine-containing mother liquor in the production process of 3-chloro-2-hydrazinylpyridine.

[0007] In the first aspect, the present application provides a method for recycling hydrazine hydrate, which adopts the following technical solution:

[0008] A method for recycling hydrazine hydrate, comprising the following steps:

[0009] Primary neutralization: adding sodium hydroxide solution into the hydrazine-containing mother liquor to make the pH value of the system 10-12, to obtain a neutralized solution;

[0010] Dehydrazination: the hydrazine hydrate in the neutralized solution is dissociated into gaseous hydrazine, which penetrates through the gas transmission membrane into the sulfuric acid absorption solution, is cooled, filtered, and then a crude hydrazine sulfate crystal is obtained;

[0011] Secondary neutralization: the crude hydrazine sulfate crystal is put into the sodium hydroxide solution for neutralization, to obtain a hydrazine hydrate mixture;

[0012] Separation and purification: the hydrazine hydrate mixture is evaporated under vacuum, and then condensed to obtain a hydrazine hydrate product.

[0013] By adopting the above technical solution, the main components of the hydrazine-containing mother liquor generated in the production process of 3-chloro-2-hydrazinylpyridine are hydrochloric acid hydrazine, hydrazine hydrate, residual 3-chloro-2-hydrazinylpyridine, hydrazinylpyridine polymer and water; the hydrochloric acid hydrazine reacts with sodium hydroxide in the primary neutralization step to generate hydrazine hydrate and sodium chloride, to obtain a neutralized solution; the gas-liquid transmission membrane has the characteristic of selective penetration of substances, and the gas can penetrate in both directions, while the liquid cannot penetrate; the sulfuric acid absorption solution and the hydrazine hydrate establish gas-liquid contact on both sides of the gas-liquid transmission membrane. The gaseous hydrazine hydrate dissociated from the hydrazine hydrate can penetrate through the gas transmission membrane into the sulfuric acid absorption solution, and is enriched in the sulfuric acid absorption solution, and the reaction becomes a crude hydrazine sulfate crystal. The solubility of hydrazine sulfate increases with the increase of water temperature, therefore, the cooling crystallization method is adopted to make the hydrazine sulfate precipitate. The hydrazine sulfate reacts with sodium hydroxide to generate sodium sulfate and hydrazine hydrate, to obtain a hydrazine hydrate mixture containing sodium sulfate impurities. Since the boiling point of hydrazine hydrate is much lower than that of sodium sulfate and water, after vacuum evaporation, the hydrazine hydrate is discharged in gas phase, and finally the hydrazine hydrate liquid is collected by condensation; the sodium sulfate crystal is discharged in solid phase. Through actual detection, the purity of the hydrazine hydrate reaches more than 99.95%, and the yield of the hydrazine hydrate reaches more than 85%.

[0014] Further, the hydrazine-containing mother liquor is preheated before the primary neutralization step, and in the preheating step, the preheating temperature is 85-90℃.

[0015] By adopting the above technical solution, the preheating treatment of the hydrazine-containing mother liquor helps to increase the movement speed of the hydrazine molecules, thereby helping the gaseous hydrazine molecules to penetrate through the gas transmission membrane and be absorbed by the sulfuric acid absorption solution, improving the recovery efficiency of the hydrazine hydrate, and thus reducing the area of the gas transmission membrane. Moreover, the preheating temperature is controlled to be not more than 90℃, to reduce the possibility of decomposition of the hydrazine hydrate at high temperature, and to ensure the yield of the hydrazine hydrate.

[0016] Further, in the filtration and dehydrazination step, the pH value of the sulfuric acid absorption solution is controlled to be below 1.5.

[0017] By adopting the above technical scheme, the sulfuric acid absorption liquid is continuously supplemented with sulfuric acid, so that the pH value of the sulfuric acid absorption liquid is maintained below 1.5, thereby helping the sulfuric acid absorption liquid to maintain good absorption effect on hydrazine hydrate.

[0018] Further, in the filter hydrazine step, the cooling temperature is 10-20℃.

[0019] By adopting the above technical scheme, the solubility of hydrazine sulfate increases with the increase of temperature, and in this cooling temperature range, the solubility of hydrazine sulfate is low, which can ensure as much hydrazine sulfate as possible to be crystallized and precipitated, and the energy consumption required below this temperature range is high, which is not conducive to controlling the production cost.

[0020] Further, the gas transmission membrane is composed of a plurality of hollow fiber gas transmission membrane filaments made of PTFE material.

[0021] Further, in the hydrazine removal step, the neutralization liquid waste obtained by filtration is subjected to evaporation concentration, cooling, and secondary filtration to obtain a circulating mother liquor, and the circulating mother liquor is added to the hydrazine-containing mother liquor.

[0022] By adopting the above technical scheme, the neutralization liquid waste obtained by filtration generally still contains 3-5% hydrazine hydrate, therefore, the neutralization liquid waste is subjected to evaporation concentration, concentrated to the saturation state of sodium chloride solution, cooled, and then the sodium chloride is precipitated, and the secondary filtration is performed, and the hydrazine hydrate in the circulating mother liquor is subjected to alkaline neutralization again, so that the hydrazine hydrate in the hydrazine-containing mother liquor is fully recovered.

[0023] Further, in the secondary neutralization step, the temperature of the sodium hydroxide solution is 40-60℃.

[0024] By adopting the above technical scheme, the hydrazine sulfate crystals react with the hot sodium hydroxide solution, and in this temperature range, the reaction process is accelerated, and the possibility of evaporation of the generated hydrazine hydrate is reduced.

[0025] Further, in the separation and purification step, the evaporation temperature is 70-80℃.

[0026] By adopting the above technical scheme, in this temperature range, the hydrazine hydrate can be fully evaporated, and the possibility of decomposition of the hydrazine hydrate at high temperature is reduced, and the hydrazine hydrate product with high purity and high yield is recovered.

[0027] In a second aspect, the application provides a device for recycling hydrazine hydrate, which adopts the following technical scheme:

[0028] A device for recycling hydrazine hydrate, which implements the method for recycling hydrazine hydrate, and comprises a primary alkaline neutralization tank, a hydrazine removal module, a secondary alkaline neutralization tank, a first vacuum evaporator, and a second heat exchanger arranged in sequence.

[0029] The hydrazine-containing mother liquor and the sodium hydroxide solution are blended in the primary alkali neutralization tank, and the obtained neutralization liquid flows into the hydrazine removal module;

[0030] The hydrazine removal module comprises a membrane contactor, a first heat exchanger and a first filter arranged in sequence, the membrane contactor comprises a shell, a gas transmission membrane is arranged in the shell, a neutralization liquid inlet, a sulfuric acid solution inlet and a sulfuric acid solution outlet are formed on the shell, and the neutralization liquid inlet communicates with the gas transmission membrane; after the hydrazine hydrate contained in the neutralization liquid is dissociated into gaseous hydrazine and enters the shell through the pores of the gas transmission membrane, the sulfuric acid absorption liquid flows out from the sulfuric acid solution outlet, sequentially flows through the first heat exchanger and the first filter, and the hydrazine sulfate crude crystal is obtained.

[0031] The hydrazine sulfate crude crystal and the sodium hydroxide solution are blended in the secondary alkali neutralization tank, and the obtained hydrazine hydrate mixed liquid is obtained.

[0032] The hydrazine hydrate mixed liquid sequentially flows through the first vacuum evaporator and the second heat exchanger, and the second heat exchanger is condensed to obtain the hydrazine hydrate product.

[0033] By adopting the above technical scheme, the device is simple and is conducive to realizing industrial production.

[0034] Further, a filter membrane part is arranged in the shell, and the filter membrane part is located at the sulfuric acid solution outlet.

[0035] By adopting the above technical scheme, the filter membrane part performs secondary filtration on the sulfuric acid absorption liquid containing hydrazine sulfate, and the purity of the hydrazine sulfate in the sulfuric acid absorption liquid is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a schematic diagram of the device structure for recovering hydrazine hydrate in Example 1.

[0037] Figure 2 It is a schematic diagram of the cross-sectional structure of the membrane contactor.

[0038] REFERENCE NUMERALS:

[0039] 1, preheating tank; 2, primary alkali neutralization tank; 3, hydrazine removal module; 31, membrane contactor; 311, shell; 312, neutralization liquid inlet; 313, water distribution pipe; 314, gas transmission membrane; 315, water collecting pipe; 316, sulfuric acid solution inlet; 317, sulfuric acid solution outlet; 318, filter membrane part; 319, neutralization liquid waste water outlet; 32, first heat exchanger; 33, sulfuric acid absorption liquid recovery tank; 4, secondary alkali neutralization tank; 5, first vacuum evaporator; 6, second heat exchanger; 7, second vacuum evaporator; 8, third heat exchanger; 9, second filter. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present application more clear, the device of the present application is further described in detail below in combination with the drawings and specific embodiments. The advantages and features of the present application will be more clear according to the following description. It should be noted that the drawings are very simplified and all use non-precise proportions, only for the purpose of facilitating and clearly assisting the description of the embodiments of the present application. In order to make the purpose, features and advantages of the present application more obvious and easy to understand, please refer to the drawings. It should be noted that the structure, proportion, size and the like shown in the drawings of the present application are only used to cooperate with the content disclosed in the description, so that those skilled in the art can understand and read, and are not used to limit the conditions for implementing the present application, so they do not have substantial technical significance. Any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effect and purpose that can be achieved by the present application, should fall within the scope of the technical content disclosed by the present application.

[0041] Examples

[0042] Example 1

[0043] Figure 1 For the structure diagram of the hydrazine hydrate recovery device of Example 1, see Figure 1 The hydrazine hydrate recovery device comprises a preheating tank 1, a primary alkali neutralization tank 2, a hydrazine removal module 3, a secondary alkali neutralization tank 4, a first vacuum evaporator 5 and a second heat exchanger 6 arranged in sequence. The hydrazine-containing mother liquor is first preheated in the preheating tank 1, and then flows into the primary alkali neutralization tank 2 to be neutralized with alkali liquor. The hydrazine-containing mother liquor contains hydrochloric acid hydrazine impurities which are converted into hydrazine hydrate and sodium chloride. The obtained neutralization liquid flows into the hydrazine removal module 3. The hydrazine hydrate is dissociated into gaseous hydrazine which is absorbed by sulfuric acid absorption liquid. After cooling and filtering, it is converted into hydrazine sulfate crystals. The hydrazine sulfate crystals are neutralized with alkali liquor in the secondary alkali neutralization tank 4, and are converted into hydrazine hydrate. The hydrazine hydrate is evaporated by the first vacuum evaporator 5, and then condensed by the second heat exchanger 6 to complete the separation and purification, and obtain high-purity hydrazine hydrate product.

[0044] See Figure 1 The preheating tank 1 comprises a tank body and heat exchange pipelines fixed in the tank body. One end of the tank body is provided with a liquid inlet, and the other end of the tank body is provided with a liquid outlet. The hydrazine-containing mother liquor enters from the liquid inlet, is heated to 85-90℃ by the heat exchange pipelines, and then flows to the primary alkali neutralization tank 2 from the liquid outlet.

[0045] See Figure 1The sidewall of the primary alkali neutralization tank 2 is provided with a preheated mother liquor inlet for the preheated hydrazine-containing mother liquor to flow into the primary alkali neutralization tank 2; the top of the primary alkali neutralization tank 2 is provided with a lye inlet, and the sodium hydroxide solution flows into the primary alkali neutralization tank 2 from the lye inlet to contact the hydrazine-containing mother liquor in countercurrent, so that the hydrazine dihydrochloride in the hydrazine-containing mother liquor and a small amount of evaporated hydrazine-containing mother liquor can fully react with sodium hydroxide to generate hydrazine hydrate and sodium chloride, and the neutralization liquid is obtained.

[0046] Referring to Figure 1 The top of the primary alkali neutralization tank 2 is also provided with a pH detector which extends into the primary alkali neutralization tank 2 for real-time monitoring of the pH value of the neutralization liquid, so that the pH value of the neutralization liquid is controlled at 10-12; at the same time, the operator can adjust the flow rate or concentration of the sodium hydroxide solution in a timely manner according to the data feedback of the pH detector, so as to ensure that the pH value of the neutralization liquid is maintained within a stable range. The bottom of the primary alkali neutralization tank 2 is provided with a neutralization liquid outlet, and the neutralization liquid is pumped into the hydrazine removal module 3 through the neutralization liquid outlet.

[0047] Referring to Figure 1 The hydrazine removal module 3 comprises a membrane contactor 31, a first heat exchanger 32 and a first filter which are sequentially connected. Figure 2 It is a cross-sectional structure diagram of the membrane contactor 31. Referring to Figure 1 and Figure 2 The membrane contactor 31 comprises a shell 311, one end of the shell 311 is provided with a neutralization liquid inlet 312, and the shell 311 is sequentially provided with a water distribution pipe 313, a gas transmission membrane 314 and a water collecting pipe 315 along the flow direction of the neutralization liquid. The neutralization liquid inlet 312 is in communication with the water distribution pipe 313, the water distribution pipe 313 is in communication with the gas transmission membrane 314, the gas transmission membrane 314 is composed of a plurality of hollow fiber gas transmission membrane filaments made of PTFE material, the hollow fiber gas transmission membrane filaments block the water and organic matter contained in the neutralization liquid from flowing into the shell 311, and the hydrazine hydrate in the neutralization liquid can penetrate through the pores of the hollow fiber gas transmission membrane filaments after being dissociated into gaseous hydrazine to enter the shell 311. The sidewall of the shell 311 is provided with a sulfuric acid solution inlet 316 and a sulfuric acid solution outlet 317, and the sulfuric acid absorbing liquid enters the shell 311 through the sulfuric acid solution inlet 316 to absorb gaseous hydrazine. The gaseous hydrazine on the side of the sulfuric acid absorbing liquid is always absorbed by sulfuric acid to become hydrazinium sulfate, so in this gas-liquid mass transfer system, the hydrazine gas partial pressure on the acid side is close to zero. However, the hydrazine gas partial pressure in the neutralization liquid always exists, which forms a driving force to make the hydrazine hydrate in the neutralization liquid continuously dissociate into gaseous hydrazine and water, and the gaseous hydrazine continuously vaporizes to penetrate through the gas transmission membrane 314, and the hydrazinium sulfate flows out from the sulfuric acid solution outlet 317 with the sulfuric acid absorbing liquid.

[0048] Referring to Figure 2In order to further improve the purity of hydrazine sulfate, the filter membrane part 318 is arranged in the shell 311. The filter membrane part 318 is in the shape of a ring. Two filter membrane parts 318 are arranged on the water distribution pipe 313 and the water collecting pipe 315 respectively. The filter membrane part 318 is located at the sulfuric acid solution inlet 316 and the sulfuric acid solution outlet 317. The filter membrane part 318 is made of polytetrafluoroethylene. The sulfuric acid absorption solution containing hydrazine sulfate is filtered twice, and further organic impurities are intercepted.

[0049] With reference to Figure 1 The sulfuric acid solution outlet 317 is connected with the first heat exchanger 32. The sulfuric acid absorption solution containing hydrazine sulfate is cooled in the first heat exchanger 32. After being cooled to 10-20℃, the sulfuric acid absorption solution is pumped into the first filter. Since the solubility of hydrazine sulfate decreases with the decrease of temperature, the hydrazine sulfate in the sulfuric acid absorption solution is precipitated. The sulfuric acid absorption solution is filtered through the first filter to obtain hydrazine sulfate coarse crystals. The hydrazine sulfate coarse crystals are transferred to the second alkali neutralization tank 4 for secondary neutralization.

[0050] With reference to Figure 1 The first filter is provided with the sulfuric acid absorption solution recovery tank 33. The filtered sulfuric acid absorption solution is pumped into the sulfuric acid absorption solution recovery tank 33. In order to ensure the absorption effect of the sulfuric acid absorption solution on gaseous hydrazine, the sulfuric acid absorption solution recovery tank 33 is continuously supplemented with sulfuric acid, so that the pH value of the sulfuric acid absorption solution is maintained below 1.5. The sulfuric acid absorption solution is re-injected into the sulfuric acid solution inlet 316 to realize the recycling use of the sulfuric acid solution.

[0051] With reference to Figure 1 The sodium hydroxide solution is injected into the top of the second alkali neutralization tank 4. The temperature of the sodium hydroxide solution is 40-60℃. In this temperature range, the hydrazine sulfate can rapidly react with the sodium hydroxide to generate sodium sulfate and hydrazine hydrate, and the hydrazine hydrate mixed solution containing sodium sulfate impurities is obtained.

[0052] With reference to Figure 1 The hydrazine hydrate mixed solution is pumped into the first vacuum evaporator 5. The evaporation temperature in the first vacuum evaporator 5 is 70-80℃, and the evaporation pressure is 19.2kPa (absolute pressure). Since the boiling point of hydrazine hydrate is much lower than that of sodium sulfate and water, after vacuum evaporation, the hydrazine hydrate is discharged in the form of gas. The first vacuum evaporator 5 is connected with the second heat exchanger 6. The hydrazine hydrate liquid is obtained by condensation in the second heat exchanger 6. The purity of the hydrazine hydrate product is ≥99.95%. At the same time, the sodium sulfate impurities are discharged from the first vacuum evaporator 5 in the form of crystals.

[0053] With reference to Figure 1 and Figure 2The other end of the shell 311 is provided with a neutralized liquid waste outlet 319, which is communicated with the collecting pipe 315. The neutralized liquid waste filtered by the filter core 314 is collected in the collecting pipe 315 and flows out from the neutralized liquid waste outlet 319. Since part of the hydrazine hydrate in the neutralized liquid waste is not absorbed by the sulfuric acid absorbing liquid, 3-5% of the hydrazine hydrate remains in the neutralized liquid waste. In order to fully recover the hydrazine hydrate, a second vacuum evaporator 7 is arranged after the dehydrazination module 3. The second vacuum evaporator 7 continuously evaporates and concentrates the neutralized liquid waste to the saturation state of the sodium chloride solution. The second vacuum evaporator 7 is sequentially connected with a third heat exchanger 8 and a second filter 9. The third heat exchanger 8 condenses the concentrated neutralized liquid waste, and the sodium chloride contained in the neutralized liquid waste is crystallized and separated out. After being filtered by the second filter 9, the neutralized liquid waste containing the hydrazine hydrate reenters the preheating tank 1 and enters the preheating tank 1 together with the hydrazine-containing mother liquor for recycling.

[0054] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

[0055] It should be noted that, the above-described embodiments only express several implementation manners of the present disclosure, and the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present disclosure. It should be pointed out that, for those skilled in the art, without departing from the concept of the present disclosure, a number of modifications and improvements can be made, which all belong to the protection scope of the present disclosure. Therefore, the patent protection scope of the present disclosure should be subject to the appended claims.

Claims

1. A method of recovering hydrazine hydrate, characterized by, The method comprises the following steps: Primary neutralization: adding sodium hydroxide solution into the hydrazine-containing mother liquor to obtain a neutralization liquid with pH value of 10-12; Hydrazine hydrochloride reacts with sodium hydroxide in the primary neutralization step to generate hydrazine hydrate and sodium chloride, thereby obtaining the neutralization liquid; Dehydrazination: the hydrazine hydrate contained in the neutralization liquid is dissociated into gaseous hydrazine, which penetrates the dehydrazination module (3) into the sulfuric acid absorption liquid, is cooled, and is filtered to obtain crude hydrazine sulfate crystals; The dehydrazination module (3) comprises a membrane contactor (31), a first heat exchanger (32) and a first filter arranged in sequence, the membrane contactor (31) comprises a shell (311) provided with a gas transmission membrane (314) therein, the shell (311) is provided with a neutralization liquid inlet (312), a sulfuric acid solution inlet (316) and a sulfuric acid solution outlet (317), and the neutralization liquid inlet (312) is in communication with the gas transmission membrane (314); after the hydrazine hydrate contained in the neutralization liquid is dissociated into gaseous hydrazine, the gaseous hydrazine penetrates the pores of the gas transmission membrane (314) into the shell (311), while the liquid cannot penetrate, and the sulfuric acid absorption liquid flows out from the sulfuric acid solution outlet (317), sequentially flows through the first heat exchanger (32) and the first filter, and finally crude hydrazine sulfate crystals are obtained; Secondary neutralization: the crude hydrazine sulfate crystals are put into sodium hydroxide solution for neutralization to obtain a hydrazine hydrate mixture; Separation and purification: the hydrazine hydrate mixture is evaporated under vacuum conditions to obtain hydrazine hydrate product through condensation.

2. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: The hydrazine-containing mother liquor is preheated before the primary neutralization step, and the preheating temperature is 85-90°C in the preheating step.

3. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: In the filtration dehydrazination step, the pH value of the sulfuric acid absorption liquid is controlled to be below 1.

5.

4. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: In the dehydrazination step, the cooling temperature is 10-20°C.

5. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: In the dehydrazination step, the neutralization liquid waste obtained after dehydrazination is evaporated, concentrated, cooled and secondarily filtered to obtain a circulating mother liquor, which is added into the hydrazine-containing mother liquor.

6. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: In the secondary neutralization step, the temperature of the sodium hydroxide solution is 40-60°C.

7. A process for recovering hydrazine hydrate as claimed in claim 1 wherein: In the separation and purification step, the evaporation temperature is 70-80°C.

8. An apparatus for recovering hydrazine hydrate, characterized by: The method for recycling hydrazine hydrate according to claims 1-7 comprises a primary alkali neutralization tank (2), a dehydrazination module (3), a secondary alkali neutralization tank (4), a first vacuum evaporator (5) and a second heat exchanger (6) arranged in sequence; The hydrazine-containing mother liquor and the sodium hydroxide solution are mixed in the primary alkali neutralization tank (2) to obtain a neutralization liquid which is then fed into the dehydrazination module (3). The dehydrazine module (3) comprises a membrane contactor (31), a first heat exchanger (32) and a first filter arranged in sequence, the membrane contactor (31) comprises a shell (311), a gas transmission membrane (314) is arranged in the shell (311), a neutralization liquid inlet (312), a sulfuric acid solution inlet (316) and a sulfuric acid solution outlet (317) are arranged on the shell (311), the neutralization liquid inlet (312) is communicated with the gas transmission membrane (314); after hydrazine hydrate contained in the neutralization liquid is dissociated into gaseous hydrazine and enters the shell (311) through the pores of the gas transmission membrane (314), the liquid cannot be transmitted, the sulfuric acid absorbing liquid flows out from the sulfuric acid solution outlet (317), sequentially flows through the first heat exchanger (32) and the first filter, and the crude hydrazine sulfate crystal is obtained; The crude hydrazine sulfate crystal and a sodium hydroxide solution are mixed in the secondary alkali neutralization tank (4), and the obtained hydrazine hydrate mixed liquid is obtained; The hydrazine hydrate mixed liquid sequentially flows through the first vacuum evaporator (5) and the second heat exchanger (6), the second heat exchanger (6) is condensed, and the hydrazine hydrate product is obtained.

9. An apparatus for recovering hydrazine hydrate as claimed in claim 8 wherein: The shell (311) is provided with a filter membrane part (318), and the filter membrane part (318) is located at the sulfuric acid solution outlet (317).

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