A hydrazine hydrate tail gas treatment system and method

Abstract

The present invention provides a tail gas treatment system and method for hydrazine hydrate, wherein the tail gas treatment system is connected with a distillation system and a production system, and the production system is connected with the distillation system; the production system includes a hydrazine production reactor; the distillation system includes an evaporation heating device, a foam trap, and a distillation tower connected in sequence; the tail gas treatment system includes a steam compressor and a condenser, the first outlet pipe at the top of the distillation tower is connected with the condenser, the second outlet pipe at the top of the distillation tower is connected with the inlet of the steam compressor, the top outlet pipe of the hydrazine production reactor is connected with the inlet of the steam compressor, and the outlet of the steam compressor is directly connected with the heating pipe of the evaporation heating device. In the tail gas treatment system for hydrazine hydrate described in the present invention, the steam compressor can compress the tail gas of the distillation tower and the hydrazine production reactor into high-temperature and high-pressure steam, and use it as a heating heat source for the evaporation heating device, which not only saves energy and reduces consumption; but also can avoid condensing the tail gas into wastewater, thereby reducing wastewater discharge.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a hydrazine hydrate tail gas treatment system and method. Background Art

[0002] The molecular formula of hydrazine hydrate is N2H4·H2O. Hydrazine hydrate, also known as hydrated ammonia, is a colorless, transparent, oily liquid with a light ammonia smell. It smokes in humid air and is highly alkaline and hygroscopic. The freezing point of hydrazine hydrate is -51.7℃, the boiling point is 120.1℃, and the liquid density is 1.032g / cm at 25℃. 3 The surface tension is 74.0 mN / m at 25°C, the refractive index is 1.4284, the heat of formation is -242.71 KJ / mol, and the flash point (open cup method) is 72.8°C.

[0003] Liquid hydrazine hydrate exists in the form of dimer, which is miscible with water and ethanol, but insoluble in ether and chloroform; it can corrode glass, rubber, leather, cork, etc., and decompose into N2, NH3 and H2 at high temperature; hydrazine hydrate has extremely strong reducing property and can react violently with halogen, HNO3, KMnO4, etc., and can absorb CO2 in the air to produce smoke.

[0004] Hydrazine hydrate is an important chemical raw material. It can not only be used as a raw material for pesticides, medicines, intermediates, dyes, developers, and antioxidants, but can also be used to manufacture high-purity metals, synthetic fibers, and separate rare elements. In addition, it can also be used as a raw material for rocket fuel and explosives.

[0005] The specifications of hydrazine hydrate used in commercial applications are: 40%, 60%, 80% and 100%. In the current industrial production, whether the urea method, ketone nitrogen method or hydrogen peroxide method is used to produce hydrazine hydrate, its initial concentration cannot reach the concentration required by the commodity. Therefore, it must go through evaporation and distillation to be upgraded to the commodity specification standard, or enter the next process. Evaporation and distillation is to evaporate the initial product first, and introduce the hydrazine hydrate gas and water vapor produced in this process into the distillation tower for distillation and concentration to reach the commodity standard. However, a large amount of mixed tail gas containing a certain concentration of hydrazine hydrate and water vapor will inevitably be produced during the distillation and concentration process, and these tail gases need to be treated before they can be discharged because the ammonia nitrogen content is greater than the national atmospheric emission standard.

[0006] The patent with application number CN202011055474.8 in the prior art discloses a purification process of hydrazine hydrate, comprising the following steps: 1) using crude hydrazine hydrate as a raw material, adding it to a distillation tower, and then adding sodium hydroxide solution to the distillation tower, controlling the bottom temperature of the distillation tower to be 117-125°C, and the pressure to be 0.01-0.02MPa; 2) step 1) the vapor phase discharged from the top of the distillation tower is adsorbed by an adsorption bed, and then enters a distillation tower in the form of a vapor phase for distillation, controlling the top temperature of the distillation tower to be 98-100°C, and the bottom temperature to be 115-123°C, and obtaining a hydrazine hydrate product with a concentration of 100% at the bottom of the tower. Although this patent can simply and continuously concentrate and purify crude hydrazine hydrate while reducing the impurity content in hydrazine hydrate to obtain a 100% pure hydrazine hydrate product, the method for treating the tail gas in the distillation tower is to send the tail gas into a condenser for forced condensation into condensed water, which not only wastes a lot of heat, but also consumes a lot of water and electricity, increasing energy waste; furthermore, it will increase the discharge of wastewater and cause environmental pollution.

[0007] In addition, if the pressure at the top of the distillation tower is too low, air will enter the system. Since 80% hydrazine hydrate at high temperature is flammable, there will be safety hazards in the system. If the pressure at the top of the distillation tower is too high, the hydrazine content in the tail gas will be high and the system yield will be low. It is very important to achieve a high tail gas recovery rate, a high energy saving rate of the system, and at the same time ensure the stability of the pressure and temperature at the top of the distillation tower and the pressure stability of the entire system.

[0008] In view of this, the present invention is proposed. Summary of the invention

[0009] The purpose of the present invention is to provide a tail gas treatment system and method for hydrazine hydrate, so as to solve the problem that the distillation system for producing 80% hydrazine hydrate in the prior art sends the tail gas from the distillation tower into a condenser for forced condensation into condensed water, which not only wastes a lot of heat, but also consumes a lot of water and electricity, increasing energy waste; furthermore, it also increases the discharge of wastewater and causes environmental pollution.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] A tail gas treatment system for hydrazine hydrate, wherein the tail gas treatment system is connected to a distillation system and a production system, the production system is connected to the distillation system, the production system is used to produce 40% hydrazine hydrate, the distillation system is used to purify 40% hydrazine hydrate to obtain 80% hydrazine hydrate, and the tail gas treatment system is used to recycle the tail gas generated by the production system and the distillation system;

[0012] The production system includes a hydrazine production reactor;

[0013] The distillation system comprises an evaporation and heating device, a foam trap, a distillation tower, a cooler and a hydrazine storage tank which are connected in sequence;

[0014] The tail gas treatment system comprises a steam compressor and a condenser, the first outlet pipe at the top of the distillation tower is connected to the condenser, the second outlet pipe at the top of the distillation tower is connected to the inlet of the steam compressor, the top outlet pipe of the hydrazine reactor is connected to the inlet of the steam compressor, and the outlet of the steam compressor is directly connected to the heating pipe of the evaporation heating device;

[0015] The steam compressor can compress the tail gas evaporated from the distillation tower and the hydrazine production reactor into high-temperature and high-pressure steam, and use it as a heating heat source for the evaporation heating device.

[0016] The invention provides a tail gas treatment system for hydrazine hydrate, wherein a second outlet pipeline at the top of a rectifying tower is connected to a steam compressor, a top outlet pipeline of a hydrazine production reactor is connected to an inlet of the steam compressor, and an outlet of the steam compressor is directly connected to a heating pipeline of an evaporation heating device; the arrangement of the steam compressor can compress tail gas evaporated from the rectifying tower and the hydrazine production reactor into high-temperature and high-pressure steam, and the high-temperature and high-pressure steam from the steam compressor can enter the heating pipeline of the evaporation heating device as a heating heat source, gradually replace the raw steam to heat 40% hydrazine hydrate in the evaporation heating device, and convert the liquid 40% hydrazine hydrate into water vapor and hydrazine hydrate vapor azeotropic gas, which then enters the rectifying tower. On the one hand, the demand for external energy can be reduced, thereby achieving the effect of saving steam, realizing the recycling of heat energy, and saving energy and reducing consumption; on the other hand, the tail gas can be prevented from being condensed into waste water, thereby reducing waste water discharge and greatly reducing environmental pollution.

[0017] Furthermore, the evaporation and heating device includes an evaporator and a heater, the evaporator and the heater are installed at the same height, the bottom outlet of the evaporator is connected to the bottom inlet of the heater, the top outlet of the heater is connected to the top inlet of the evaporator, 40% hydrazine hydrate is transported to the evaporator from the middle inlet of the evaporator, and the top outlet of the evaporator is connected to the foam collector.

[0018] Furthermore, the outlet of the steam compressor is connected to the inlet of the heating pipe of the heater.

[0019] Furthermore, the distillation system also includes a preheater, which is arranged between the 40% hydrazine hydrate delivery pipeline and the evaporator. The preheater is used to heat the 40% hydrazine hydrate before entering the evaporator. A third valve is arranged between the 40% hydrazine hydrate delivery pipeline and the preheater.

[0020] Furthermore, a heating pipe outlet of the heater is connected to a heating pipe inlet of the preheater, and the preheater is arranged below the heater.

[0021] Furthermore, the outlet of the heating pipe of the preheater is connected to a reflux water tank, the reflux water tank is arranged below the preheater, the reflux water tank is connected to the top inlet of the distillation tower, and a reflux water pump is arranged between the reflux water tank and the top inlet of the distillation tower.

[0022] Furthermore, a tail gas condensation regulating valve is arranged between the distillation tower and the condenser.

[0023] Furthermore, a hydrazine production microreactor is arranged before the hydrazine production reactor, and the hydrazine production microreactor is used to fully and evenly mix urea and sodium hypochlorite under low temperature.

[0024] Furthermore, the distillation system also includes a raw steam pipeline, which includes a first branch, a second branch and a third branch. The first branch is connected to the heating pipeline of the heater of the evaporation heating device, and a first raw steam valve and a third flow measuring device are arranged on the first branch; the second branch is connected to the heating pipeline of the bottom of the distillation tower, and a second raw steam valve and a fourth flow measuring device are arranged on the second branch; the third branch is connected to the heating pipeline of the hydrazine production reactor, and a third raw steam valve and a fifth flow measuring device are arranged on the third branch.

[0025] A tail gas treatment method for producing 80% hydrazine hydrate, the tail gas treatment method using any one of the above-mentioned tail gas treatment systems for hydrazine hydrate,

[0026] The tail gas treatment method comprises the following steps:

[0027] S1, the initial start-up stage, the first valve, the second valve, the third valve, the first steam valve, the second steam valve, the third steam valve, and the tail gas condensation regulating valve are opened, urea and sodium hypochlorite react with sodium hydroxide in the hydrazine reactor to obtain 40% hydrazine hydrate; 40% hydrazine hydrate is added to the evaporation heating device, and heated in the evaporation heating device to form an azeotropic gas of water vapor and hydrazine hydrate vapor; the azeotropic gas enters the distillation tower after passing through the foam trap, and 80% hydrazine hydrate product is obtained in the bottom of the distillation tower. Tail gas is generated at the top of the distillation tower, and the tail gas is directly sent to the condenser;

[0028] S2, obtaining the oxygen content in the tail gas at the top of the distillation tower, and determining whether the oxygen content is equal to zero. If so, proceed to step S3 to switch to the start-up phase; if not, maintain the original state;

[0029] S3, entering the conversion start-up phase, starting the steam compressor, first keeping the compressor inlet and outlet regulating valves in the open state; then gradually closing the tail gas condensation regulating valve, the compressor inlet and outlet regulating valves, and the first steam generation valve in combination with the tower top pressure of the distillation tower, the material liquid level of the evaporator, and the temperature of the heater until the tail gas condensation regulating valve, the compressor inlet and outlet regulating valves, and the first steam generation valve are completely closed;

[0030] S4: The system enters the stable driving stage.

[0031] Compared with the prior art, the tail gas treatment system and method of hydrazine hydrate described in the present invention have the following beneficial effects:

[0032] The tail gas treatment system and method of hydrazine hydrate described in the present invention comprises the following steps: the second outlet pipe at the top of the distillation tower is connected to the steam compressor; the top outlet pipe of the hydrazine production reactor is connected to the inlet of the steam compressor, and the outlet of the steam compressor is directly connected to the heating pipe of the evaporation heating device; the arrangement of the steam compressor can compress the tail gas evaporated from the distillation tower and the hydrazine production reactor into high-temperature and high-pressure steam, and the high-temperature and high-pressure steam from the steam compressor can enter the evaporation heating device as a heating heat source, gradually replacing the raw steam to heat the 40% hydrazine hydrate in the evaporation heating device, and converting the liquid 40% hydrazine hydrate into water The azeotropic gas of steam and hydrazine hydrate steam then enters the distillation tower, realizing the primary utilization of the tail gas; after the high-temperature and high-pressure steam heats the 40% hydrazine hydrate in the evaporation heating device, it is condensed into condensed water at about 100°C, and the condensed water flows into the preheater at a lower position to preheat the 40% hydrazine hydrate in the preheater, realizing the secondary utilization of the tail gas; the water temperature of the 40% hydrazine hydrate condensed water in the preheater is reduced to about 70°C, and enters the reflux water tank, and then the reflux water pump is used to transport the condensed water in the reflux water tank to the top of the distillation tower for use as reflux water at the top of the distillation tower, realizing the tertiary utilization of the tail gas. The tail gas treatment system is interconnected with the production system and the distillation system. The steam compressor, condenser, reflux water tank and reflux water pump, hydrazine reactor, preheater, steam heating device, foam collector, distillation tower, cooler and hydrazine storage tank are interconnected, playing multiple roles: First, it can reduce the demand for external energy, maximize the recovery of heat energy, and achieve the effect of energy saving and consumption reduction; second, it can avoid condensing the tail gas into waste water, reduce wastewater discharge, and greatly reduce environmental pollution; third, the reflux water spray at the top of the distillation tower can absorb a small amount of residual hydrazine in the tail gas on the one hand, and control the hydrazine content of the tail gas to below 0.1g / l; on the other hand, it can accurately control the top temperature of the distillation tower to prevent the phenomenon of hydrazine in the tail gas caused by temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a process flow chart of a tail gas treatment system for hydrazine hydrate according to an embodiment of the present invention;

[0034] Figure 2 A partial process flow chart of a tail gas treatment system of hydrazine hydrate according to an embodiment of the present invention;

[0035] Figure 3 A top view of a buffer tank of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0036] Figure 4 for Figure 3 Sectional view along section line AA;

[0037] Figure 5 A top view of a pressure stabilizing component of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0038] Figure 6 for Figure 5 One of the sectional views along section line AA;

[0039] Figure 7 A top view of a buffer substrate of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0040] Figure 8 A schematic top view of the structure of a first balance sensing device of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0041] Fig. 9 It is a schematic cross-sectional structural diagram of a first balance sensing device of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0042] Fig.10 This is one of the structural schematic diagrams of a retractable plug assembly of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0043] Fig.11 This is a second structural schematic diagram of a retractable plug assembly of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention;

[0044] Fig.12 for Figure 5 Sectional view 2 along section line AA;

[0045] Fig.13 for Figure 5 Sectional view 3 along section line AA;

[0046] Fig.14 for Figure 5 Sectional view 4 along section line AA;

[0047] Fig.15 A structural cross-sectional view of a hydrazine hydrate tail gas treatment system of an embodiment of the present invention;

[0048] Fig.16 This is a structural bottom view of a hydrazine production microreactor of a hydrazine hydrate tail gas treatment system according to an embodiment of the present invention.

[0049] Description of reference numerals:

[0050] 1. Preheater; 2. Evaporator; 3. Heater; 4. Foam collector; 5. Distillation tower; 6. Buffer tank; 60. Voltage stabilizing assembly; 61. Buffer substrate; 611. First vent; 612. Pressure regulating vent; 613. Central support column; 62. Voltage stabilizing adjustment plate; 621. Second vent; 63. Retractable plug assembly; 631. Plug; 632. Retractable part; 6321. First retractable body; 6322. Second retractable body; 6323. Third retractable body; 64. First balance induction device; 641. Center ball; 642. Plane; 643. Sliding resistor; 6431. Sliding part; 6432. Stationary part; 7. Steam compressor; 71. Pressure regulating pipeline; 701. First pipeline; 702. Second pipeline; 703. Third pipeline; 704. Fourth pipeline; 705. Fifth pipeline; 8. Reflux tank; 9. Reflux water Pump; 10. Cooler; 11. Hydrazine storage tank; 12. Condenser; 13. Three-stage reflux water circuit; 131. First reflux water circuit; 1311. First reflux water valve; 132. Second reflux water circuit; 1321. Second reflux water valve; 133. Third reflux water circuit; 1331. Third reflux water valve; 101. Compressor inlet and outlet regulating valves; 102. First steam valve; 103. Second steam valve; 104. Tail gas condensation regulating valve; 105. Third valve; 106. Third steam valve; 107. First valve; 108. Second valve; 14. Hydrazine microreactor; 141. Scalable refrigeration component; 142. Second balance induction device; 143. First feed pipeline; 144. Second feed pipeline; 145. Discharge pipeline; 146. Rotary stirring component; 15. Hydrazine reactor; 16. Desalination system. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0053] Example 1

[0054] In the prior art, when high-concentration hydrazine hydrate is produced by distillation and purification, the method for treating the tail gas in the distillation tower 5 is to send all the tail gas into the condenser 12 for forced condensation into condensed water, which not only wastes a lot of heat, but also consumes a lot of water and electricity, increasing energy waste; furthermore, it will increase the discharge of wastewater and cause environmental pollution.

[0055] In order to solve the above problems, Figures 1 to 16 As shown, a tail gas treatment system of hydrazine hydrate according to an embodiment of the present invention,

[0056] The tail gas treatment system is connected with the distillation system and the production system, and the production system is connected with the distillation system. The production system is used to produce 40% hydrazine hydrate, and the distillation system is used to purify 40% hydrazine hydrate to obtain 80% hydrazine hydrate. The tail gas treatment system is used to recycle the tail gas generated by the production system and the distillation system;

[0057] Specifically, the process for synthesizing hydrazine hydrate in the production system is not specifically limited. The process for synthesizing hydrazine hydrate in the production system may be a process for synthesizing hydrazine hydrate by the urea method, a process for synthesizing hydrazine hydrate by the ketazine method, or a process for synthesizing hydrazine hydrate by the hydrogen peroxide method.

[0058] In this embodiment, the process for synthesizing hydrazine hydrate in the production system is a urea process for synthesizing hydrazine hydrate, and the reaction equation is:

[0059] H2NCONH2+NaCIO+2NaOH→N2H4·H2O+NaCI+Na2CO3.

[0060] Specifically, the production system includes a hydrazine production reactor 15, and the hydrazine production reactor 15 is used to prepare 40% hydrazine hydrate.

[0061] In the prior art process of producing hydrazine hydrate by the urea method, urea, sodium hypochlorite and catalyst sodium hydroxide are simultaneously put into the hydrazine reactor 15 for reaction. However, there are several problems in this process:

[0062] 1. Sodium hypochlorite will decompose and release active oxygen during the heating process, while hydrazine hydrate is a strong reducing agent. The two are prone to redox reactions, which may lead to a decrease in the yield of hydrazine hydrate.

[0063] 2. Urea and sodium hydroxide may also undergo a side reaction at high temperature to produce ammonia, which will also reduce the yield of hydrazine hydrate.

[0064] In order to solve these problems, the applicant has improved the process. The main improvement is that a hydrazine production microreactor 14 is arranged before the hydrazine production reactor 15, and the hydrazine production microreactor 14 is used to fully mix urea and sodium hypochlorite at low temperature.

[0065] The advantages of this are: 1. Since the mixing is carried out at a low temperature, the decomposition of sodium hypochlorite is effectively suppressed, thereby reducing the generation of active oxygen and reducing the risk of redox reaction with hydrazine hydrate. 2. After entering the hydrazine production reactor 15, the fully mixed urea and sodium hypochlorite can react more evenly with sodium hydroxide, thereby improving the reaction efficiency and the purity of the product.

[0066] In this embodiment, if Fig.15 and Fig.16 As shown, a first feed pipeline 143 is provided on the hydrazine-making microreactor 14, and the first feed pipeline 143 is used to transport urea to the hydrazine-making microreactor 14; a second feed pipeline 144 is provided on the hydrazine-making microreactor 14, and the second feed pipeline 144 is used to transport sodium hypochlorite to the hydrazine-making microreactor 14; a discharge pipeline 145 is provided on the hydrazine-making microreactor 14, and the discharge pipeline 145 is used to output urea and sodium hypochlorite uniformly mixed in the hydrazine-making microreactor 14. A first valve 107 is provided on the first feed pipeline 143; and a second valve 108 is provided on the second feed pipeline 144.

[0067] A retractable refrigeration component 141 and a second equilibrium induction device 142 are arranged on the hydrazine-making microreactor 14 .

[0068] The retractable refrigeration component 141 can keep the hydrazine-making microreactor 14 at a low temperature. The material of the retractable refrigeration component 141 is not specifically limited.

[0069] In this embodiment, the material of the retractable refrigeration component 141 is a magnetic refrigeration material. Magnetic refrigeration material is a non-polluting refrigeration material that realizes refrigeration based on the magnetocaloric effect of the material. Magnetic refrigeration uses an external magnetic field to cause the magnetic moment of the magnetic medium to undergo orderly and disordered changes (phase change) to cause the magnet to absorb and release heat to perform a refrigeration cycle. Magnetic refrigeration is considered to be a "green" refrigeration method that does not emit any harmful gases such as Freon, and is expected to replace the energy-intensive and environmentally harmful gas compression refrigeration method currently in use.

[0070] Specifically, the specific type of the magnetic refrigeration material is not specifically limited.

[0071] The retractable refrigeration component 141 is retractable. By adjusting the retractable state of the retractable refrigeration component 141, the temperature requirements of different reaction stages can be better adapted, and the accuracy and flexibility of temperature control can be improved.

[0072] The second balance sensing device 142 can sense the balance state of the hydrazine-making microreactor 14 and adjust the current size that triggers the extension and retraction of the retractable refrigeration component 141 to adjust the extension or retraction of the retractable refrigeration component 141, so as to loosen the scale at the bottom of the hydrazine-making microreactor 14 and avoid scaling.

[0073] The structure and principle of the second balance sensing device 142 are the same as those of the first balance sensing device 64 , and are not described in detail herein.

[0074] Specifically, the second balance sensing device 142 is disposed at the bottom center of the hydrazine-making microreactor 14 , which is conducive to directly sensing the scaling condition of the hydrazine-making microreactor 14 , thereby performing the adjustment operation more accurately.

[0075] A rotating stirring assembly 146 is provided on the hydrazine-making microreactor 14, and the rotating stirring assembly 146 is retractably arranged above the interior of the hydrazine-making microreactor 14. The rotating stirring assembly 146 is used to perform rotating stirring above the interior of the hydrazine-making microreactor 14 to promote uniform mixing of reactants, improve reaction efficiency and product quality. The retractable setting of the rotating stirring assembly 146 enables it to adjust the stirring position according to the reaction requirements, so that it can go deep into the material for preliminary mixing at the initial stage of the reaction, and can also be adjusted to an appropriate position in the middle and late stages of the reaction to avoid unnecessary interference with the reaction.

[0076] By combining the retractable refrigeration component 141, the second balance induction device 142 and the rotary stirring component 146, the hydrazine microreactor 14 system can achieve fine control of the reaction conditions, effectively prevent scaling problems, and ensure the stability and efficiency of the reaction process. This integrated design concept is of great significance for improving the automation level and product quality of the chemical production process.

[0077] In addition, in order to further improve the purity of hydrazine hydrate, the applicant also sets a desalination system 16 after the hydrazine production reactor 15. The main function of the desalination system 16 is to remove salts (such as NaCl, Na2CO3) in the product. Through the desalination system 16, it can be ensured that the final 40% hydrazine hydrate has a high purity.

[0078] In summary, the applicant has effectively solved the problems existing in the original process and improved the yield and purity of hydrazine hydrate by arranging a hydrazine production microreactor 14 before the hydrazine production reactor 15 and a desalination system 16 after the hydrazine production reactor 15.

[0079] The structural principle of the desalination system 16 is prior art and will not be described in detail here.

[0080] The distillation system comprises an evaporation and heating device, a frother 4, a distillation tower 5, a cooler 10 and a hydrazine storage tank 11 connected in sequence.

[0081] The evaporation heating device is used to heat 40% hydrazine hydrate to boil and generate water vapor and hydrazine hydrate vapor azeotropic gas. The evaporation heating device includes an evaporator 2 and a heater 3.

[0082] The mist collector 4 is used to capture the mist liquid particles in the azeotropic gas of water vapor and hydrazine hydrate vapor coming out of the evaporation heating device;

[0083] The bottom of the distillation tower 5 is connected to a cooler 10, and the cooler 10 is connected to a hydrazine storage tank 11.

[0084] A tail gas condensation regulating valve 104 is provided between the distillation tower 5 and the condenser 12;

[0085] The tail gas treatment system includes a steam compressor 7 and a condenser 12, the first outlet pipe at the top of the distillation tower 5 is connected to the condenser 12, the second outlet pipe at the top of the distillation tower 5 is connected to the inlet of the steam compressor 7, the top outlet pipe of the hydrazine reactor 15 is connected to the inlet of the steam compressor 7, and the outlet of the steam compressor 7 is directly connected to the heating pipe of the evaporation heating device;

[0086] The steam compressor 7 can compress the tail gas evaporated from the distillation tower 5 and the hydrazine production reactor 15 into high-temperature and high-pressure steam, and use it as a heating heat source for the evaporation heating device.

[0087] The absolute pressure of the tail gas evaporated from the distillation tower 5 is 0.108 MPa and the temperature is 102° C. The absolute pressure of the high-temperature and high-pressure steam is greater than or equal to 0.4 MPa and the temperature is greater than or equal to 143.6° C.

[0088] In the present application, the high-temperature and high-pressure steam generated by the steam compressor 7 has an absolute pressure of 0.4 MPa and a temperature of 143.6° C., which can completely replace the raw steam to heat the 40% hydrazine hydrate solution in the heater 3 .

[0089] Specifically, the distillation system also includes a raw steam pipeline, which includes a first branch, a second branch and a third branch. The first branch is connected to the heating pipeline of the heater 3, and a first raw steam valve 102 and a third flow measuring device are arranged on the first branch; the second branch is connected to the heating pipeline of the bottom of the distillation tower 5, and a second raw steam valve 103 and a fourth flow measuring device are arranged on the second branch; the third branch is connected to the heating pipeline of the hydrazine production reactor 15, and a third raw steam valve 106 and a fifth flow measuring device are arranged on the third branch.

[0090] The third flow measuring device is used to detect the raw steam flow rate entering the heating pipeline of the heater 3. The fourth flow measuring device is used to detect the raw steam flow rate entering the heating pipeline of the tower kettle of the distillation tower 5. The fifth flow measuring device is used to detect the raw steam flow rate entering the heating pipeline of the hydrazine reactor 15.

[0091] First, urea and sodium hypochlorite react with sodium hydroxide in a hydrazine reactor 15 to obtain 40% hydrazine hydrate, and then 40% hydrazine hydrate is added to the evaporator 2. When the hydrazine hydrate raw liquid is started, the heater 3 is heated by raw steam. After the 40% hydrazine hydrate raw liquid is heated and boiled by the heater 3, water vapor and hydrazine hydrate vapor azeotropic gas are generated. The water vapor and hydrazine hydrate vapor azeotropic gas enters the foam trap 4 to capture the mist liquid particles and then enters the distillation tower 5. In the distillation tower 5, the hydrazine hydrate with a higher boiling point flows downward through the steam trap 4. The lower packing layer flows to the bottom of the distillation tower 5, and the hydrazine content gradually increases, and finally condenses into a hydrazine hydrate product with a hydrazine content of 80%. The discharge is controlled by the bottom liquid level. Since the high-temperature 80% hydrazine hydrate is flammable, it must be cooled to below 40°C by a cooler 10 before being discharged to the hydrazine storage tank 11 for storage; the water vapor with a lower boiling point flows upward through the upper packing layer in the distillation tower 5 to the top of the distillation tower 5, and the hydrazine content gradually decreases. When it reaches the top of the tower, it is basically water vapor with a very low hydrazine content. The tail gas of the distillation tower 5 is water vapor and a small amount of hydrazine hydrate vapor. Under normal circumstances, the top pressure of the distillation tower 5 is a slight positive pressure of 0.108MPa and the temperature is 102°C.

[0092] The present invention provides a tail gas treatment system for hydrazine hydrate, wherein the tail gas treatment system is interconnected with a production system and a distillation system, wherein a steam compressor 7, a condenser 12, a reflux water tank 8, a reflux water pump 9, a hydrazine production reactor 15, a preheater 1, a steam heating device, a foam trap 4, a distillation tower 5, a cooler 10 and a hydrazine storage tank 11 are interconnected, wherein a second outlet pipe at the top of the distillation tower 5 is connected to the steam compressor 7; the steam compressor 7 is connected to a heating pipe of an evaporation heating device; the steam compressor 7 is arranged to transfer the tail gas evaporated from the distillation tower 5 and the hydrazine production reactor 15 to the steam compressor 7; The gas is compressed into high-temperature and high-pressure steam. The high-temperature and high-pressure steam coming out of the steam compressor 7 can enter the heating pipe of the evaporation heating device as a heating heat source, gradually replacing the raw steam to heat the 40% hydrazine hydrate in the evaporation heating device, and converting the liquid 40% hydrazine hydrate into water vapor and hydrazine hydrate vapor azeotropic gas and then entering the distillation tower 5. On the one hand, it can reduce the demand for external energy, thereby achieving the effect of saving steam, realizing the recycling of heat energy, and saving energy and reducing consumption; on the other hand, it can avoid condensing the tail gas into waste water, reducing waste water discharge, and greatly reducing environmental pollution.

[0093] Specifically, Figure 1 As shown, the bifurcation point A between the first outlet pipe and the second outlet pipe at the top of the distillation tower 5, the top outlet pipe of the hydrazine production reactor 15 is connected to the bifurcation point A, and this arrangement enables the top outlet pipe of the hydrazine production reactor 15 to be connected to the first outlet pipe at the top of the distillation tower 5, and the top outlet pipe of the hydrazine production reactor 15 is also connected to the second outlet pipe at the top of the distillation tower 5.

[0094] The top outlet pipe of the hydrazine production reactor 15 is simultaneously connected to the first outlet pipe and the second outlet pipe at the top of the distillation tower 5. On the one hand, the system can adjust the exhaust gas flow direction as needed, thereby improving the reliability and safety of the system. On the other hand, it is convenient to accurately control the parameters such as the pressure of the distillation tower 5 to ensure the stable operation of the system.

[0095] Specifically, the evaporator 2 and the heater 3 are installed at the same height, the bottom outlet of the evaporator 2 is connected to the bottom inlet of the heater 3, the top outlet of the heater 3 is connected to the top inlet of the evaporator 2, 40% hydrazine hydrate is transported to the evaporator 2 from the middle inlet of the evaporator 2, and the top outlet of the evaporator 2 is connected to the foam trap 4. More specifically, the foam trap 4 is arranged directly above the evaporator 2.

[0096] This installation method ensures that the low-temperature liquid material in the evaporator 2 can flow smoothly into the heater 3, and the high-temperature steam in the heater 3 can also flow back to the evaporator 2 without hindrance, forming an efficient heat circulation loop. The equal height design also allows the liquid level in the evaporator 2 to remain flush with the upper end of the heat exchange tube of the heater 3, so that the thermal energy in the heater 3 can be maximized and the thermal efficiency can be improved. The foam catcher 4 is cleverly arranged directly above the evaporator 2. This layout helps to more effectively capture the mist liquid particles in the azeotropic gas. When the azeotropic gas passes through the foam catcher 4, the mist liquid particles therein will flow back to the evaporator 2 under the action of gravity, thereby reducing the impurity content in the azeotropic steam and improving the purity and quality of the final product. At the same time, this design also reduces the burden on the foam catcher 4 and extends its service life.

[0097] The above arrangement enables the material to be heated and boiled in a circulation between the evaporator 2 and the heater 3, thereby ensuring the continuity and uniformity of the reaction; the low-temperature liquid material in the evaporator 2 enters the heater 3 for heating and is completely converted into a water vapor and hydrazine hydrate vapor azeotropic gas, and enters the top of the evaporator 2 from the top of the heater 3 and then enters the foam collector 4, thereby firstly realizing continuous circulation heating and boiling of the material between the evaporator 2 and the heater 3; secondly, part of the mist liquid particles in the water vapor and hydrazine hydrate vapor azeotropic gas can be made to flow back to the evaporator 2, thereby reducing the burden on the foam collector 4 and facilitating the long-term stable operation of the equipment; and thirdly, the entire system has a compact structure and a reasonable layout, which is convenient for daily maintenance and operation.

[0098] More specifically, the outlet of the steam compressor 7 is connected to the inlet of the heating pipe of the heater 3 .

[0099] This arrangement facilitates the high-temperature and high-pressure steam from the steam compressor 7 to enter the heating pipe of the heater 3 as the heating heat source of the heater 3, gradually replacing the raw steam to heat the 40% hydrazine hydrate in the heater 3, and converting the liquid 40% hydrazine hydrate into water vapor and hydrazine hydrate vapor azeotropic gas and then entering the distillation tower 5. On the one hand, it can reduce the demand for external energy and realize the primary recycling of thermal energy, thereby achieving the effect of saving steam, realizing the recycling of thermal energy, saving energy and reducing consumption; on the other hand, it can avoid condensing the tail gas into wastewater, reducing wastewater discharge, and greatly reducing environmental pollution.

[0100] The distillation system further comprises a preheater 1, which is arranged between the 40% hydrazine hydrate delivery pipeline and the evaporator 2, and is used to heat the 40% hydrazine hydrate before entering the evaporator 2. A third valve 105 is arranged between the 40% hydrazine hydrate delivery pipeline and the preheater 1.

[0101] More specifically, the preheater 1 is used to preheat the raw material 40% hydrazine hydrate liquid to 55-65°C.

[0102] More specifically, the heating pipe outlet of the heater 3 is connected to the heating pipe inlet of the preheater 1 , and the preheater 1 is arranged below the heater 3 .

[0103] The high-temperature and high-pressure steam in the heating pipe of the heater 3 heats 40% hydrazine hydrate and condenses it into condensed water at about 100°C. This arrangement facilitates the condensed water in the heating pipe of the heater 3 to flow into the preheater 1 at a lower position to preheat the 40% hydrazine hydrate in the preheater 1. On the one hand, it can reduce the demand for external energy and realize the secondary recycling of thermal energy to maximize the recovery of thermal energy and achieve the effect of energy saving and consumption reduction; on the other hand, it can avoid condensing the tail gas into wastewater, reduce wastewater discharge, and greatly reduce environmental pollution.

[0104] More specifically, the outlet of the heating pipe of the preheater 1 is connected to the reflux water tank 8, the reflux water tank 8 is arranged below the preheater 1, the reflux water tank 8 is connected to the top inlet of the distillation tower 5, and a reflux water pump 9 is arranged between the reflux water tank 8 and the top inlet of the distillation tower 5. The reflux water pump 9 is a centrifugal water pump, and the material of the flow-through parts of the reflux water pump 9 is 304 stainless steel.

[0105] The temperature of the condensed water coming out of the preheater 1 is about 70° C. This arrangement facilitates the condensed water in the heating pipe of the preheater 1 to flow into the reflux water tank 8 at a lower position, and then be transported to the top of the distillation tower 5 by the reflux water pump 9 to be used as reflux water at the top of the distillation tower 5. First, it can reduce the demand for external energy and realize the three-fold recycling of thermal energy to maximize the recovery of thermal energy and achieve the effect of energy saving and consumption reduction; second, it can avoid condensing the tail gas into waste water, reduce waste water discharge, and greatly reduce environmental pollution; third, spraying the top of the distillation tower 5 with reflux water can absorb a small amount of residual hydrazine in the tail gas, improve the yield of hydrazine hydrate, and control the hydrazine content of the tail gas below 0.1 g / l; fourth, when the reflux water is sprayed, the temperature at the top of the distillation tower 5 decreases, and the pressure also decreases accordingly, and the system temperature and pressure can be adjusted.

[0106] like Figure 2 As shown, a three-stage reflux waterway 13 is arranged between the reflux water tank 8 and the top of the distillation tower 5, and the three-stage reflux waterway 13 includes a first reflux waterway 131, a second reflux waterway 132 and a third reflux waterway 133. A first reflux water valve 1311 is arranged on the first reflux waterway 131, a second reflux water valve 1321 is arranged on the second reflux waterway 132, and a third reflux water valve 1331 is arranged on the third reflux waterway 133.

[0107] Specifically, the steam compressor 7 is a high-speed variable frequency centrifugal compressor, which is started by a high-speed variable frequency motor, and the shaft seal of the steam compressor 7 adopts a labyrinth seal. When the steam compressor 7 is running, water vapor with a certain pressure is filled to prevent air from entering the shell and affecting the heat exchange efficiency of the heater 3 behind.

[0108] Specifically, the distillation tower 5 includes a distillation tower body, a tower bottom and a packing layer, and a heating coil is arranged on the tower bottom. This arrangement is conducive to stabilizing the control of the product concentration of 80% hydrazine hydrate in the tower bottom, ensuring the product quality and ensuring safe production.

[0109] The foam catcher 4 is a wire mesh filter made of 304 stainless steel.

[0110] The evaporator 2 is an empty tank made of 304 stainless steel.

[0111] The preheater 1 , the heater 3 , and the cooler 10 are all shell-and-tube heat exchangers, and the flow-through parts of the preheater 1 , the heater 3 , and the cooler 10 are all made of 304 stainless steel.

[0112] In order to stabilize the top pressure of the distillation tower 5, the applicant specifically Figure 1 As shown, a pressure regulating pipeline 71 is arranged between the inlet pipeline and the outlet pipeline of the steam compressor 7 .

[0113] The arrangement of the pressure regulating pipeline 71 can stabilize the pressure at the top of the distillation tower 5, ensure the smooth operation of the distillation tower 5, and prevent the hydrazine from escaping due to pressure fluctuations.

[0114] Specifically, Figure 1 As shown, the inlet pipeline of the steam compressor 7 includes a first pipeline 701 and a second pipeline 702 connected, and the tail gas enters from the inlet of the first pipeline 701. The first pipeline 701 is vertically arranged, and the second pipeline 702 is vertically arranged below the first pipeline 701. The second pipeline 702 is connected to the steam compressor 7. The steam compressor 7 can compress the tail gas evaporated from the distillation tower 5 into high-temperature and high-pressure steam, and use it as a heating heat source for the evaporation heating device. The outlet pipeline of the steam compressor 7 includes a third pipeline 703, a fourth pipeline 704 and a fifth pipeline 705 connected in sequence, the third pipeline 703 is vertically arranged above the steam compressor 7, the fourth pipeline 704 is vertically arranged above the third pipeline 703, and the fifth pipeline 705 is vertically arranged below the fourth pipeline 704. The high-temperature and high-pressure steam is output from the third pipeline 703, the fourth pipeline 704 and the fifth pipeline 705 in sequence.

[0115] Specifically, Figure 1As shown, the pressure regulating pipeline 71 is arranged horizontally, and the height of the pressure regulating pipeline 71 is equal to the height of the fourth pipeline 704. Such a design facilitates balanced adjustment of the steam pressure at the inlet and outlet of the steam compressor 7, while also taking into account the need for smooth steam flow and pressure balance. One end of the pressure regulating pipeline 71 is connected to the first pipeline 701, and the other end of the pressure regulating pipeline 71 is connected to both the third pipeline 703 and the fourth pipeline 704. This design allows the steam to form a circulation or bypass path between the inlet and outlet, thereby achieving fine adjustment of the system pressure.

[0116] In order to further precisely control the top pressure of the distillation tower 5 , the applicant installed a compressor inlet and outlet regulating valve 101 on the pressure regulating pipeline 71 .

[0117] The amount of tail gas entering the pressure regulating pipe 71 can be adjusted by the opening of the compressor inlet and outlet regulating valve 101, thereby realizing the pressure regulation of the top of the distillation tower 5. When the top pressure of the distillation tower 5 is too high, the opening of the compressor inlet and outlet regulating valve 101 can be reduced to allow more tail gas to enter the steam compressor 7 through the second pipe 702, thereby reducing the top pressure; conversely, when the top pressure is too low, the opening of the compressor inlet and outlet regulating valve 101 can be increased to limit the tail gas from entering the steam compressor 7 through the second pipe 702, thereby increasing the top pressure.

[0118] This arrangement facilitates the pressure regulating pipeline 71 to regulate the top pressure of the distillation tower 5 to be stable through the compressor inlet and outlet regulating valves 101 .

[0119] In order to further stabilize the pressure of the system, the applicant installed a buffer tank 6 between the distillation tower 5 and the steam compressor 7 .

[0120] This setting firstly plays the role of buffering and stabilizing pressure, adjusting system pressure and temperature, and avoiding large fluctuations in system pressure; secondly, plays the role of gas-liquid separation, preventing liquid in the tail gas from entering the steam compressor 7 and damaging the steam compressor 7.

[0121] The bottom outlet of the buffer tank 6 is connected to the middle inlet of the side wall of the evaporator 2. On the one hand, it is convenient to recycle the liquid in the tail gas; on the other hand, it avoids the problem of potential safety hazards caused by the liquid being discharged into the air.

[0122] In order to further stabilize the pressure of the system, the tail gas with uneven and stable pressure entering the buffer tank 6 is buffered into tail gas with stable pressure. Preferably, Figure 4 , Figure 5 and Figure 6 As shown, a pressure stabilizing component 60 is arranged in the buffer tank 6, and the pressure stabilizing component 60 can effectively buffer the tail gas with uneven pressure into the tail gas with stable pressure, so as to facilitate the subsequent processing.

[0123] like Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the voltage stabilizing component 60 includes:

[0124] A buffer substrate 61, the buffer substrate 61 is fixedly connected to the buffer tank 6, and a first vent hole 611 and a pressure regulating vent hole 612 are provided on the buffer substrate 61;

[0125] A voltage stabilizing and regulating plate 62, wherein the voltage stabilizing and regulating plate 62 is fixedly connected to the buffer tank 6, the voltage stabilizing and regulating plate 62 is arranged above the buffer substrate 61, and a second vent hole 621 is arranged on the voltage stabilizing and regulating plate 62;

[0126] A retractable plug assembly 63, wherein the retractable plug assembly 63 is installed below the voltage stabilizing and regulating plate 62, and when the retractable plug assembly 63 is extended, the pressure regulating vent hole 612 on the buffer substrate 61 can be blocked, and when the retractable plug assembly 63 is retracted, the pressure regulating vent hole 612 on the buffer substrate 61 can be opened;

[0127] The first balance sensing device 64 is installed at the center position of the bottom of the buffer substrate 61. The first balance sensing device 64 is used to sense the balance state of the buffer substrate 61 and adjust the current size that triggers the extension and retraction of the retractable plug assembly 63 to adjust the extension or retraction of the retractable plug assembly 63, so that the area of ​​the pressure regulating vent 612 of the buffer substrate 61 through which the exhaust gas passes increases or decreases, thereby increasing or decreasing the outflow rate and pressure of the exhaust gas, so that the exhaust pressure flowing out of the pressure stabilizing assembly 60 is basically stable, thereby ensuring the pressure stability of the system while realizing the exhaust gas recovery and utilization.

[0128] Specifically, Fig.10 As shown, the retractable plug assembly 63 includes a plugging portion 631 and a retractable portion 632 , and the plugging portion 631 is connected to the retractable portion 632 .

[0129] like Figure 4 and Fig.10 As shown, the diameter of the plugging portion 631 is greater than or equal to the diameter of the pressure regulating vent hole 612 . This arrangement facilitates the plugging portion 631 to seal the pressure regulating vent hole 612 .

[0130] like Fig.10 and Fig.11 As shown, the telescopic portion 632 includes a plurality of telescopic bodies arranged vertically up and down, and the circuits for triggering the telescopic movement of each telescopic body are connected in parallel.

[0131] The number of telescopic bodies included in the telescopic portion 632 is not specifically limited.

[0132] In this embodiment, if Fig.10and Fig.11 As shown, the telescopic portion 632 includes a first telescopic body 6321 , a second telescopic body 6322 and a third telescopic body 6323 which are connected in sequence.

[0133] The diameter of the first telescopic body 6321 is smaller than the diameter of the second telescopic body 6322 , and the diameter of the second telescopic body 6322 is smaller than the diameter of the third telescopic body 6323 .

[0134] More specifically, the plugging portion 631 is connected to the first telescopic body 6321 , and the diameter of the first telescopic body 6321 is greater than or equal to the diameter of the plugging portion 631 .

[0135] More specifically, in this embodiment, if Fig.10 As shown, the diameter of the first telescopic body 6321 is equal to the diameter of the plugging part 631 .

[0136] like Figure 4 As shown, a central support column 613 is provided between the buffer substrate 61 and the voltage regulating plate 62, the upper end of the central support column 613 is connected to the voltage regulating plate 62, and the lower end of the central support column 613 is connected to the buffer substrate 61. This arrangement improves the structural stability of the voltage stabilizing assembly 60.

[0137] When the first balance sensing device 64 detects that the buffer substrate 61 is unbalanced due to the uneven impact air pressure, the first balance sensing device 64 adjusts the current that triggers the extension and retraction of the retractable plug assembly 63 to adjust the extension or retraction of the retractable plug assembly 63, so that the exhaust gas passes through the pressure regulating vent 612 of the buffer substrate 61 to be blocked or opened, thereby increasing or decreasing the outflow rate and pressure of the exhaust gas, so that the exhaust gas pressure flowing out of the pressure stabilizing assembly 60 is basically stable.

[0138] like Figure 8 and Fig. 9 As shown, the first balance sensing device 64 includes a center ball 641 located at the center of the bottom of the buffer substrate 61, a plane 642 supporting the center ball 641, and a sliding resistor 643 arranged along the line connecting the center ball 641 and the retractable plug assembly 63 in the corresponding direction; the sliding resistor 643 includes a sliding part 6431 and a stationary part 6432, the sliding part 6431 is sleeved on the outer side of the stationary part 6432, and the outer end of the sliding part 6431 is connected to the center ball 641; the number of the sliding resistor 643, the retractable plug assembly 63, and the pressure regulating vent 612 is the same, and the sliding resistor 643 is connected in series with the circuit that triggers the retractability of the retractable plug assembly 63. The setting of the first balance sensing device 64 can quickly and accurately control the magnitude of the current of the retractable plug assembly 63.

[0139] Specifically, the number of the sliding resistor 643, the retractable plug assembly 63, and the pressure regulating vent hole 612 is not specifically limited.

[0140] In this embodiment, if Figure 7 and Figure 8 The number of the sliding resistor 643, the retractable plug assembly 63, and the pressure regulating vent hole 612 is five.

[0141] When it is detected that the buffer substrate 61 is unbalanced due to the uneven impact pressure, the first balance sensing device 64 controls the central ball 641 to tilt and slide to one side, pushing the sliding part 6431 of the sliding resistor 643 on the tilted side to slide toward the static part 6432 to reduce the resistance; the sliding part 6431 of the sliding resistor 643 on the other side slides toward the outside of the static part 6432 to increase the resistance; thereby, the current passing through the corresponding retractable plug assembly 63 increases and decreases, causing the retractable plug assembly 63 on the tilted side to extend and the retractable plug assembly 63 on the other side to shorten; it can be seen that after the central ball 641 slides, it has different degrees of extension-inducing effect on the multiple retractable plug assemblies 63 on one side of the tilt direction, and different degrees of shortening effect on the multiple retractable plug assemblies 63 on the other side of the tilt direction; thereby increasing or decreasing the outflow rate and pressure of the exhaust gas, so that the exhaust pressure flowing out of the voltage stabilizing assembly 60 is basically stable, and the pressure stability of the system can be ensured while realizing the exhaust gas recovery and utilization.

[0142] In summary, the pressure regulating pipeline 71 and the compressor inlet and outlet regulating valves 101 thereon, the buffer tank 6 and the pressure stabilizing component 60 therein play a vital role in the exhaust gas treatment system. They work together to achieve refined and automated control of the top pressure of the distillation tower 5, ensuring the efficient recovery and utilization of the exhaust gas while ensuring the stability of the top pressure of the distillation tower 5 and the stable operation of the system, preventing the hydrazine escape phenomenon caused by pressure fluctuations, and ensuring the smooth progress of the distillation process and the overall safety of the system.

[0143] This embodiment also provides a method for treating tail gas of hydrazine hydrate, wherein the tail gas treatment method uses any one of the above-mentioned tail gas treatment systems of hydrazine hydrate.

[0144] The tail gas treatment method comprises the following steps:

[0145] S1, the initial start-up stage, the first valve 107, the second valve 108, the third valve 105, the first steam valve 102, the second steam valve 103, the third steam valve 106, and the tail gas condensation regulating valve 104 are opened, urea and sodium hypochlorite react with sodium hydroxide in the hydrazine reactor 15 to obtain 40% hydrazine hydrate; 40% hydrazine hydrate is added to the evaporation heating device, and heated in the evaporation heating device to form an azeotropic gas of water vapor and hydrazine hydrate vapor; the azeotropic gas enters the distillation tower 5 after passing through the frother 4, and 80% hydrazine hydrate product is obtained in the tower kettle at the bottom of the distillation tower 5, and tail gas is generated at the top of the distillation tower 5, and the tail gas is directly sent to the condenser 12;

[0146] In step S1, the exhaust gas must be produced by using live steam in the initial start-up phase. By opening the first valve 107, the second valve 108, and the third live steam valve 106, urea and sodium hypochlorite react with sodium hydroxide in the hydrazine production reactor to obtain 40% hydrazine hydrate; the third valve 105, the first live steam valve 102, and the second live steam valve 103 are opened, 40% hydrazine hydrate is added to the evaporation heating device, and heated in the evaporation heating device to form an azeotropic gas of water vapor and hydrazine hydrate vapor; the azeotropic gas is filtered out by a foam trap. After the steam compressor 7 is started, the waste water containing hydrazine is diverted to the reflux tank 8 for recycling, and the rest is sent to the sewage treatment tank for centralized treatment.

[0147] S2, obtaining the oxygen content in the tail gas at the top of the distillation tower 5, and determining whether the oxygen content is equal to zero. If so, proceed to step S3 to switch to the start-up phase; if not, maintain the original state;

[0148] The setting of step S2 is to determine whether there is still air in the system; this is to ensure that the subsequent stage can safely switch to using the steam compressor 7 to treat the exhaust gas, avoid air from damaging the steam compressor 7, and ensure system safety.

[0149] S3, entering the conversion start-up phase, starting the steam compressor 7, first keeping the compressor inlet and outlet regulating valves 101 in the open state; then gradually closing the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valves 101, and the first steam generation valve 102 in combination with the tower top pressure of the distillation tower 5, the material liquid level of the evaporator 2, and the temperature of the heater 3, until the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valves 101, and the first steam generation valve 102 are completely closed;

[0150] After confirming that there is no air in the system, start the steam compressor 7, and keep the compressor inlet and outlet regulating valves 101 open first; then gradually adjust the openings of the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valves 101, and the first steam valve 102. This step requires a comprehensive judgment based on the top pressure of the distillation tower 5, the material liquid level of the evaporator 2, and the temperature of the heater 3 to ensure a smooth transition of the system.

[0151] S4: The system enters the stable driving stage.

[0152] After closing the relevant valves, the system enters step S4 and enters the stable start-up stage. At this time, the tail gas treatment will mainly rely on the steam compressor 7, which not only achieves a high tail gas recovery rate and a high energy saving rate of the system, but also ensures that the tail gas is effectively treated and the energy therein is recycled.

[0153] The exhaust gas treatment system includes a control device, and the specific location of the control device is not specifically limited.

[0154] In the tail gas treatment method for producing 80% hydrazine hydrate by distillation and purification described in this embodiment, steps S1 to S4 are interrelated, and while achieving a high recovery rate of tail gas, the stability of the pressure and temperature at the top of the distillation tower 5 and the pressure stability of the entire system are ensured, and the system has a higher yield; the system also has higher safety.

[0155] Through meticulous operating steps and parameter adjustments, a smooth transition from the initial start-up phase to the stable start-up phase was achieved, ensuring production safety and efficiency.

[0156] The tail gas treatment system for producing 80% hydrazine hydrate by distillation and purification of the present invention is interrelated with the tail gas treatment method for producing 80% hydrazine hydrate by distillation and purification and is inseparable; the tail gas treatment system is interrelated with the distillation system, the steam compressor 7, the condenser 12, the reflux water tank 8 and the reflux water pump 9, the preheater 1, the steam heating device, the foam trap 4, the distillation tower 5, the cooler 10 and the hydrazine storage tank 11 cooperate with each other, and steps S1 to S4 are interrelated, playing multiple roles:

[0157] The steam compressor 7, the steam heating device, the preheater 1, the reflux water tank 8, the reflux water pump 9, the distillation tower 5 and other devices are interconnected to realize the three-level utilization of the tail gas of the distillation tower 5, which not only greatly reduces the demand for external energy, maximizes the recovery of heat energy, achieves the effect of energy saving and consumption reduction, and realizes a high recovery rate of tail gas; it can also avoid condensing the tail gas into waste water, reduce waste water discharge, and greatly reduce environmental pollution; the reflux water spray at the top of the distillation tower 5, on the one hand, absorbs a small amount of residual hydrazine in the tail gas, and controls the hydrazine content of the tail gas to below 0.1g / l; on the other hand, it can accurately control the top temperature of the distillation tower 5 to prevent the phenomenon of hydrazine in the tail gas caused by temperature fluctuations.

[0158] The pressure regulating pipeline 71 and the compressor inlet and outlet regulating valves 101 thereon, the buffer tank 6 and the pressure stabilizing component 60 therein play a vital role in the exhaust gas treatment system. They work together to achieve refined and automated control of the top pressure of the distillation tower 5, ensuring the stability of the top pressure of the distillation tower 5 and the stable operation of the system while ensuring the efficient recovery and utilization of the exhaust gas, preventing the hydrazine escape caused by pressure fluctuations, and ensuring the smooth progress of the distillation process and the overall safety of the system.

[0159] During the initial start-up phase, the tail gas condensation regulating valve 104 is opened, and the tail gas is directly sent to the condenser 12, which can drive away the air in the system and ensure the safety of the system.

[0160] In the conversion start-up phase, the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 101, and the first steam generation valve 102 are gradually closed in combination with the tower top pressure of the distillation tower 5, the material liquid level of the evaporator 2, and the temperature of the heater 3 until the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 101, and the first steam generation valve 102 are completely closed, thereby achieving a smooth transition from the initial start-up phase to the stable start-up phase, and ensuring the safety and efficiency of production. In the stable start-up phase, since the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 101, and the first steam generation valve 102 are completely closed, the tail gas of the distillation tower 5 is completely recycled, achieving a high tail gas recovery rate and energy recovery.

[0161] Specifically, a material liquid level sensor is arranged in the evaporator 2 , and the material liquid level sensor is used to detect the material liquid level in the evaporator 2 .

[0162] A first temperature sensor is disposed in the heater 3 , and is used to detect the temperature in the heater 3 .

[0163] An oxygen detector, a first pressure sensor and a second temperature sensor are arranged at the top of the distillation tower 5. The oxygen detector is used to detect the oxygen in the tail gas at the top of the distillation tower 5; the first pressure sensor is used to detect the pressure at the top of the distillation tower 5; and the second temperature sensor is used to detect the temperature at the top of the distillation tower 5.

[0164] A third temperature sensor, a second pressure sensor and a first flow measuring device are provided at the inlet of the steam compressor 7 .

[0165] The third temperature sensor is used to detect the temperature at the inlet of the steam compressor 7 ; the second pressure sensor is used to detect the pressure at the inlet of the steam compressor 7 ; and the first flow measurement device is used to detect the gas flow at the inlet of the steam compressor 7 .

[0166] A fourth temperature sensor, a third pressure sensor and a second flow measurement device are provided at the inlet of the steam compressor 7 .

[0167] The fourth temperature sensor is used to detect the temperature of the outlet of the steam compressor 7 ; the third pressure sensor is used to detect the pressure of the outlet of the steam compressor 7 ; and the second flow measurement device is used to detect the gas flow at the outlet of the steam compressor 7 .

[0168] Multiple sensors and detectors are installed in the system to monitor parameters such as pressure, temperature, flow, etc. in real time, and automatically adjust according to preset conditions to ensure stable operation of the system.

[0169] Specifically, step S31 includes the following steps:

[0170] S31, start the steam compressor 7, first keep the compressor inlet and outlet regulating valves 101 in an open state; start the reflux water pump 9, and open the first reflux water valve 1311 and the second reflux water valve 1321;

[0171] S32, the opening of the tail gas condensation regulating valve 104 is reduced;

[0172] Specifically, the amount by which the tail gas condensation regulating valve 104 is adjusted down is not specifically limited.

[0173] In this embodiment, the opening of the tail gas condensation regulating valve 104 is reduced by 1 / 5 of the fully open state.

[0174] S33, real-time detection of the tower top pressure P, to determine whether P satisfies P>preset pressure P0, if yes, proceed to step S34; if no, proceed to step S35;

[0175] The preset pressure P0 is system preset data, and the preset pressure P0 is data preset by the system in the system control device; in the present application, the preset pressure P0 = 0.108 MPa.

[0176] S34, entering the first step-down regulation mode.

[0177] S35, judging whether P satisfies P<preset pressure P0, if so, proceeding to step S36; if not, maintaining the original operation state;

[0178] S36, entering the first boost regulation mode.

[0179] S37. Determine whether P = preset pressure P0 and R = preset material liquid level R0 and T = preset temperature T0. If so, the opening of the compressor inlet and outlet regulating valves 101 remains unchanged, the third return water valve 1331 is closed, the operating frequency of the steam compressor 7 remains unchanged, the opening of the first steam valve 102 and the third valve 105 remains unchanged, and return to step S32; if not, return to step S37 (or re-execute step S37).

[0180] S38. Real-time detection of whether the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valves 101 and the first steam generation valve 102 are all completely closed. If so, proceed to step S4; if not, return to step S32.

[0181] Steps S31 to S38 are interrelated. The tail gas treatment method of this embodiment not only achieves a high tail gas recovery rate, a high energy saving rate of the system and effective recycling of energy, but also ensures the safe, stable and efficient operation of the entire production system.

[0182] Specifically, step S34 includes the following steps:

[0183] S341, obtain the temperature T in the heater 3, and determine whether T satisfies T=preset temperature T0. If so, proceed to step S342; if not, proceed to step S343.

[0184] The preset temperature T0 is system preset data, and the preset temperature T0 is data preset by the system in the system control device; in the present application, the preset temperature T0 = 112°C.

[0185] S342, entering the voltage reduction and temperature unchanged regulation mode;

[0186] S343, determine whether T satisfies T<preset temperature T0, if yes, proceed to step S344, if no, proceed to step S345;

[0187] S344, entering the voltage reduction and temperature increase regulation mode;

[0188] S345, entering the voltage reduction and temperature reduction regulation mode.

[0189] Specifically, step S342 includes the following steps:

[0190] S3421, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3422, if not, proceeding to step S3423;

[0191] The preset material liquid level R0 is system preset data, and the preset material liquid level R0 is data preset by the system in the system control device; in the present application, the preset material liquid level R0 = 3 / 4 of the height of the evaporator 2 .

[0192] S3422, entering the pressure reduction and temperature and liquid level unchanged regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, and the third return water valve 1331 is opened;

[0193] S3423, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3424, if not, proceed to step S3425;

[0194] S3424, enter the pressure reduction and temperature unchanged liquid level adjustment mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, and the third valve 105 is opened to a larger opening;

[0195] S3425, entering the pressure reduction and temperature unchanged liquid level adjustment mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, and the third valve 105 is opened to a smaller opening.

[0196] Specifically, step S344 includes the following steps:

[0197] S3441, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3442, if not, proceeding to step S3443;

[0198] S3442, entering the pressure reduction and temperature increase and liquid level unchanged regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, and the operating frequency of the steam compressor 7 is increased;

[0199] Wherein, an operating frequency acquisition device is provided on the steam compressor 7 ; the operating frequency acquisition device is used to acquire the operating frequency of the steam compressor 7 .

[0200] S3443, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3444, if not, proceed to step S3445;

[0201] S3444, entering the pressure reduction, temperature increase and liquid level increase regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, the operating frequency of the steam compressor 7 is increased, and the opening of the third valve 105 is increased;

[0202] S3445, entering the pressure reduction, temperature increase and liquid level reduction regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, the operating frequency of the steam compressor 7 is increased, and the opening of the third valve 105 is reduced.

[0203] Specifically, step S345 includes the following steps:

[0204] S3451, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3452, if not, proceeding to step S3453;

[0205] S3452, enter the pressure reduction and temperature reduction and liquid level unchanged regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, the third return water valve 1331 is opened, and the first steam generation valve 102 is opened to a smaller opening;

[0206] S3453, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3454, if not, proceed to step S3455;

[0207] S3454, enter the pressure reduction, temperature reduction and liquid level increase regulation mode, reduce the opening of the compressor inlet and outlet regulating valves 101, open the third return water valve 1331, reduce the opening of the first steam valve 102, and increase the opening of the third valve 105;

[0208] S3455, enter the pressure reduction, temperature reduction and liquid level reduction adjustment mode, reduce the opening of the compressor inlet and outlet regulating valves 101, open the third return water valve 1331, reduce the opening of the first steam valve 102, and reduce the opening of the third valve 105.

[0209] Specifically, step S36 includes the following steps:

[0210] S361, obtain the temperature T in the heater 3, and determine whether T satisfies T=preset temperature T0. If so, proceed to step S362; if not, proceed to step S365.

[0211] S362, entering the voltage-boosting and temperature-unchanged regulation mode;

[0212] S363, determine whether T satisfies T<preset temperature T0, if yes, proceed to step S364, if no, proceed to step S365;

[0213] S364, entering the boost and temperature regulation mode;

[0214] S365, enter the boost and temperature reduction regulation mode.

[0215] Specifically, step S362 includes the following steps:

[0216] S3621, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3622, if not, proceeding to step S3623;

[0217] S3622, enter the pressure-boosting and temperature-unchanged and liquid-level-unchanged regulation mode, increase the opening of the compressor inlet and outlet regulating valves 101, and close the third return water valve 1331;

[0218] S3623, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3624, if not, proceed to step S3625;

[0219] S3624, enter the pressure-boosting and temperature-unchanged liquid level regulating mode, the compressor inlet and outlet regulating valves 101 are opened wider, the third return water valve 1331 is closed, the third return water valve 1331 is opened, and the third valve 105 is opened wider;

[0220] S3625, enter the pressure-boosting and temperature-unchanged liquid level adjustment mode, increase the opening of the compressor inlet and outlet regulating valves 101, close the third return water valve 1331, and reduce the opening of the third valve 105.

[0221] Specifically, step S364 includes the following steps:

[0222] S3641, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3642, if not, proceeding to step S3643;

[0223] S3642, enter the pressure and temperature increase and liquid level unchanged regulation mode, the compressor inlet and outlet regulating valves 101 are opened wider, the third return water valve 1331 is closed, and the operating frequency of the steam compressor 7 is increased;

[0224] S3643, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3644, if not, proceed to step S3645;

[0225] S3644, enter the pressure, temperature and liquid level increase regulation mode, the compressor inlet and outlet regulating valves 101 are opened wider, the third return water valve 1331 is closed, the operating frequency of the steam compressor 7 is increased, and the opening of the third valve 105 is opened wider;

[0226] S3645, enter the pressure increase, temperature increase and liquid level reduction regulation mode, increase the opening of the compressor inlet and outlet regulating valves 101, close the third return water valve 1331, increase the operating frequency of the steam compressor 7, and reduce the opening of the third valve 105.

[0227] Specifically, step S365 includes the following steps:

[0228] S3651, obtaining the material liquid level R of evaporator 2, and determining whether R satisfies R=preset material liquid level R0, if so, proceeding to step S3652, if not, proceeding to step S3653;

[0229] S3652, enter the pressure increase and temperature reduction and liquid level unchanged regulation mode, the compressor inlet and outlet regulating valves 101 are opened wider, the third return water valve 1331 is closed, and the first steam valve 102 is opened narrower;

[0230] S3653, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3654, if not, proceed to step S3655;

[0231] S3654, enter the pressure increase, temperature reduction and liquid level increase regulation mode, the compressor inlet and outlet regulating valves 101 are opened wider, the third return water valve 1331 is closed, the first steam valve 102 is opened less, and the third valve 105 is opened wider;

[0232] S3655, enter the pressure increase, temperature decrease and liquid level decrease regulation mode, increase the opening of the compressor inlet and outlet regulating valves 101, close the third return water valve 1331, decrease the opening of the first steam valve 102, and decrease the opening of the third valve 105.

[0233] This series of steps and sub-steps demonstrates the complex parameter adjustment and mode switching in the exhaust gas treatment process, aiming to achieve efficient exhaust gas recovery and effective energy utilization through fine control. Each step is based on real-time monitoring of system parameters and dynamic adjustment according to preset conditions and target values ​​to ensure the safety, stability and efficiency of the entire treatment process.

[0234] Specifically, step S4 includes the following steps:

[0235] S41, real-time detection of the tower top pressure P; determine whether P satisfies P>preset pressure P0, if yes, proceed to step S42; if no, proceed to step S43;

[0236] S42, entering the second pressure reduction regulation mode, the compressor inlet and outlet regulating valves 101 are opened to a smaller opening, and the third return water valve 1331 is opened;

[0237] S43, judging whether P satisfies P<preset pressure P0, if so, proceeding to step S44; if not, maintaining the current operating state;

[0238] S44, entering the second boost regulation mode, the compressor inlet and outlet regulating valves 101 are opened wider, and the third return water valve 1331 is closed.

[0239] When the system is ready to shut down, in order to ensure the safe production of the distillation system, open the tail gas condensation regulating valve 104, and increase the opening of the tail gas condensation regulating valve 104 by 1 / 3 every hour, and then increase the opening of the compressor inlet and outlet regulating valve 101 by 1 / 3. When the openings of the tail gas condensation regulating valve 104 and the compressor inlet and outlet regulating valve 101 are adjusted to the maximum, close the steam compressor 7 to ensure a steady drop in the pressure of the distillation tower 5.

[0240] The system enters the stable start-up stage. After stable operation, observe the steam flow meter reading at this time. When the system output is 2 tons of 80% hydrazine hydrate per hour, the raw steam flow of heater 3 is 0, and the steam consumption of the tower kettle of distillation tower 5 is about 1 ton. The production of 1 ton of 80% hydrazine hydrate can save about 2 tons of steam. The price of steam is 260 yuan / ton, and the steam cost is saved by 520 yuan. The variable frequency motor used by steam compressor 7 has a rated power of 280kw. According to the maximum power calculation, the electricity fee is 0.6 yuan / kwh. The production of 1 ton of 80% hydrazine hydrate requires an additional electricity fee of 280*0.6 / 2=84 yuan.

[0241] Based on the above calculations, after recycling the tail gas, the cost of producing 80% hydrazine hydrate per ton can be saved by 520-84=436 yuan. The energy-saving effect is still very significant.

[0242] Example 2

[0243] In this embodiment, different from the embodiment 1, Figures 11 to 14 As shown, the diameter of the plugging portion 631 is smaller than the diameter of the pressure regulating vent hole 612 .

[0244] The diameter of the third telescopic body 6323 is smaller than the diameter of the pressure regulating vent hole 612 .

[0245] The retractable plug assembly 63 is used to adjust the area of ​​the exhaust gas passing through the pressure regulating vent 612, thereby increasing or decreasing the outflow rate and pressure of the exhaust gas, so that the pressure of the exhaust gas flowing out of the pressure stabilizing assembly 60 is basically stable.

[0246] When the first balance sensing device 64 detects that the buffer substrate 61 is unbalanced due to the uneven impact air pressure, the first balance sensing device 64 is controlled to adjust the current that triggers the extension and retraction of the retractable plug assembly 63 to adjust the extension or retraction of the retractable plug assembly 63, so that the area of ​​the pressure regulating vent 612 of the buffer substrate 61 through which the exhaust gas passes increases or decreases, thereby increasing or decreasing the outflow rate and pressure of the exhaust gas, so that the exhaust gas pressure flowing out of the pressure stabilizing assembly 60 is basically stable, thereby achieving exhaust gas recovery and utilization while ensuring the pressure stability of the system.

[0247] Example 3

[0248] In this embodiment, different from the embodiment 1, Fig.14 As shown, the diameter of the plugging portion 631 is smaller than the diameter of the pressure regulating vent hole 612 , the diameter of the first telescopic body 6321 is larger than the diameter of the plugging portion 631 , and the diameter of the third telescopic body 6323 is smaller than the diameter of the pressure regulating vent hole 612 .

[0249] A fourth pressure sensor is disposed at the air inlet of the buffer tank 6 , and the fourth pressure sensor is used to detect the pressure P1 of the exhaust gas entering the buffer tank 6 .

[0250] A fifth pressure sensor is disposed at the bottom of the buffer substrate 61 , and the fifth pressure sensor is used to detect the pressure P2 of the exhaust gas reaching the buffer substrate 61 .

[0251] The pressure difference of the exhaust gas from the air inlet of the buffer tank to the buffer substrate 61 is P2-P1.

[0252] In the initial start-up stage, the first telescopic body 6321 of the control telescopic plug assembly 63 is arranged inside the pressure regulating vent hole 612;

[0253] Determine whether P2-P1>the first preset pressure difference value. If so, control the retractable plug assembly 63 to retract and be set above the pressure regulating vent 612; if not, determine whether P2-P1>the second preset pressure difference value; if so, control the retractable plug assembly 63 to retract so that the plugging part 631 is set inside the pressure regulating vent 612; if not, determine whether P2-P1>the third preset pressure difference value; if so, control the retractable plug assembly 63 to extend so that the second retractable body 6322 is set inside the pressure regulating vent 612; if not, control the retractable plug assembly 63 to extend so that the third retractable body 6323 is set inside the pressure regulating vent 612.

[0254] The first preset pressure difference, the second preset pressure difference, and the third preset pressure difference are all system preset data. In the present application, the first preset pressure difference is set to 10 MPa; the second preset pressure difference is set to 0 MPa; and the third preset pressure difference is set to -10 MPa.

[0255] In this embodiment, the pressure difference P2-P1 of the exhaust gas from the air inlet of the buffer tank 6 to the buffer substrate 61 is divided into different intervals, and different processing methods are performed in different intervals. The retractable plug assembly 63 is controlled to extend or retract, so that the area of ​​the pressure regulating vent 612 of the buffer substrate 61 through which the exhaust gas passes increases or decreases, thereby facilitating the buffer tank 6 to quickly and accurately increase or decrease the outflow rate and pressure of the exhaust gas, so that the pressure of the exhaust gas flowing out of the buffer tank 6 is basically consistent with the pressure of the exhaust gas entering the buffer tank 6, thereby achieving exhaust gas recovery and utilization while ensuring the pressure stability of the system.

[0256] Comparative Example 1

[0257] In this comparative example, unlike Example 1, only a production system and a distillation system are included, but no tail gas treatment system is included. The tail gas generated by the distillation tower 5 and the hydrazine reactor 15 is always condensed by the condenser 12, and the heating heat source of the evaporator 2 is always raw steam.

[0258] Comparative Example 2

[0259] In this comparative example, different from Example 1, the exhaust gas treatment system does not include the pressure regulating pipeline 71 and the compressor inlet and outlet regulating valves 101 thereon.

[0260] Comparative Example 3

[0261] In this comparative example, different from Example 1, the exhaust gas treatment system does not include the buffer tank 6 and the pressure stabilizing component 60 therein.

[0262] Comparative Example 4

[0263] In this comparative example, different from Example 1, the tail gas treatment system only includes the condenser 12 and the steam compressor 7, and also includes a steam jet heat pump, but does not include the pressure regulating pipeline 71 and the compressor inlet and outlet regulating valves 101 thereon, the buffer tank 6 and the pressure stabilizing component 60 therein. The method of the tail gas treatment system is also different from that of Example 1, in that a part of the tail gas generated by the distillation tower 5 and the hydrazine reactor 15 is condensed by the condenser 12, and another part of the tail gas is compressed by the steam compressor 7 and then enters the steam jet heat pump, and the raw steam is introduced into the steam jet heat pump and mixed with the high-temperature and high-pressure gas coming out of the steam compressor 7 as the heating heat source of the evaporator 2.

[0264] Performance Testing

[0265] The hourly output, total steam consumption, yield and tail gas recovery rate of the systems of Examples 1 to 3 and Comparative Examples 1 to 2 are compared, and the results are shown in Table 1.

[0266] Table 1 Comparison of hourly production, total steam consumption, yield and tail gas recovery rate of the systems of Examples 1 to 3 and Comparative Examples 1 to 2

[0267]

[0268]

[0269] As can be seen from Table 1, the tail gas treatment system of a hydrazine hydrate described in Examples 1 to 3 of the present invention is related to the tail gas treatment method of a hydrazine hydrate, not only the yield of the distillation system is high, about 99.5-99.8%, but also the recovery rate of the tail gas is high, about 98.4-99.3%. In addition, compared with Comparative Example 1, Examples 1 to 3 can save about 2 tons of raw steam for every 1 ton of 80% hydrazine hydrate produced by the system. The price of raw steam is 260 yuan / ton, and the cost of raw steam is saved by 520 yuan. The energy-saving effect is significant, and the energy-saving rate is 75%.

[0270] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A tail gas treatment system for hydrazine hydrate, characterized in that, The tail gas treatment system is connected to the distillation system and the production system, and the production system is connected to the distillation system. The production system is used to produce 40% hydrazine hydrate, and the distillation system is used to purify 40% hydrazine hydrate to obtain 80% hydrazine hydrate. The tail gas treatment system is used to recycle the tail gas generated by the production system and the distillation system; The production system comprises a hydrazine production reactor (15); The distillation system comprises an evaporation and heating device, a foam trap (4), a distillation tower (5), a cooler (10) and a hydrazine storage tank (11) which are connected in sequence; The tail gas treatment system comprises a steam compressor (7) and a condenser (12), a first outlet pipe at the top of the distillation tower (5) is connected to the condenser (12), a second outlet pipe at the top of the distillation tower (5) is connected to the inlet of the steam compressor (7), a top outlet pipe of the hydrazine production reactor (15) is connected to the inlet of the steam compressor (7), and the outlet of the steam compressor (7) is directly connected to the heating pipe of the evaporation heating device; The steam compressor (7) is capable of compressing the tail gas evaporated from the distillation tower (5) and the hydrazine production reactor (15) into high-temperature and high-pressure steam, and using the steam as a heating source for the evaporation heating device; The evaporation and heating device comprises an evaporator (2) and a heater (3). The distillation system further comprises a preheater (1), wherein the preheater (1) is arranged between the 40% hydrazine hydrate delivery pipeline and the evaporator (2), and the preheater (1) is used to heat and raise the temperature of the 40% hydrazine hydrate before entering the evaporator (2). The heating pipeline outlet of the heater (3) is connected to the heating pipeline inlet of the preheater (1), and the preheater (1) is arranged below the heater (3). The outlet of the heating pipe of the preheater (1) is connected to a reflux water tank (8), the reflux water tank (8) is arranged below the preheater (1), the reflux water tank (8) is connected to the top inlet of the distillation tower (5), and a reflux water pump (9) is arranged between the reflux water tank (8) and the top inlet of the distillation tower (5); A pressure regulating pipeline (71) is provided between the inlet pipeline and the outlet pipeline of the steam compressor (7); The pressure regulating pipeline (71) is arranged horizontally, the height of the pressure regulating pipeline (71) is equal to the height of the fourth pipeline (704), one end of the pressure regulating pipeline (71) is connected to the first pipeline (701), and the other end of the pressure regulating pipeline (71) is connected to both the third pipeline (703) and the fourth pipeline (704); A compressor inlet and outlet regulating valve (101) is arranged on the pressure regulating pipeline (71); A buffer tank (6) is arranged between the distillation tower (5) and the steam compressor (7); A pressure stabilizing component (60) is arranged in the buffer tank (6), and the pressure stabilizing component (60) can effectively buffer tail gas with uneven pressure into tail gas with stable pressure.

2. A tail gas treatment system for hydrazine hydrate according to claim 1, characterized in that, The evaporator (2) and the heater (3) are installed at the same height, the bottom outlet of the evaporator (2) is connected to the bottom inlet of the heater (3), the top outlet of the heater (3) is connected to the top inlet of the evaporator (2), 40% hydrazine hydrate is transported to the evaporator (2) from the middle inlet of the evaporator (2), and the top outlet of the evaporator (2) is connected to the foam collector (4).

3. A tail gas treatment system for hydrazine hydrate according to claim 2, characterized in that, The outlet of the steam compressor (7) is connected to the inlet of the heating pipe of the heater (3).

4. A tail gas treatment system for hydrazine hydrate according to claim 3, characterized in that: A third valve (105) is provided between the 40% hydrazine hydrate delivery pipeline and the preheater (1).

5. A tail gas treatment system for hydrazine hydrate according to claim 1, characterized in that: A tail gas condensation regulating valve (104) is provided between the distillation tower (5) and the condenser (12).

6. A hydrazine hydrate tail gas treatment system according to claim 1, characterized in that: A hydrazine production microreactor (14) is arranged in front of the hydrazine production reactor (15), and the hydrazine production microreactor (14) is used to fully and evenly mix urea and sodium hypochlorite under low temperature conditions.

7. A hydrazine hydrate tail gas treatment system according to claim 1, characterized in that: The distillation system further comprises a raw steam pipeline, the raw steam pipeline comprising a first branch, a second branch and a third branch, the first branch being connected to a heating pipeline of a heater (3) of an evaporation heating device, and a first raw steam valve (102) and a third flow measuring device being arranged on the first branch; the second branch being connected to a heating pipeline of a bottom of a distillation tower (5), and a second raw steam valve (103) and a fourth flow measuring device being arranged on the second branch; the third branch being connected to a heating pipeline of a hydrazine production reactor (15), and a third raw steam valve (106) and a fifth flow measuring device being arranged on the third branch.

8. A method for treating tail gas from hydrazine hydrate, characterized in that: The tail gas treatment method uses a tail gas treatment system of hydrazine hydrate according to any one of claims 1 to 7, The tail gas treatment method comprises the following steps: S1, in the initial start-up phase, the first valve (107), the second valve (108), the third valve (105), the first steam valve (102), the second steam valve (103), the third steam valve (106), and the tail gas condensation regulating valve (104) are opened, and urea and sodium hypochlorite react with sodium hydroxide in the hydrazine production reactor (15) to obtain 40% hydrazine hydrate; the 40% hydrazine hydrate is added to the evaporation heating device, and heated in the evaporation heating device to form an azeotropic gas of water vapor and hydrazine hydrate vapor; the azeotropic gas enters the distillation tower (5) after passing through the frother (4), and an 80% hydrazine hydrate product is obtained in the bottom kettle of the distillation tower (5); tail gas is generated at the top of the distillation tower (5), and the tail gas is directly sent to the condenser (12); S2, obtaining the oxygen content in the tail gas at the top of the distillation tower (5), and determining whether the oxygen content is equal to zero. If so, proceeding to step S3 to switch to the start-up phase; if not, maintaining the original state; S3, entering the conversion start-up phase, starting the steam compressor (7), first keeping the compressor inlet and outlet regulating valves (101) in an open state; then, based on the tower top pressure of the distillation tower (5), the material liquid level of the evaporator (2), and the temperature of the heater (3), gradually closing the tail gas condensation regulating valve (104), the compressor inlet and outlet regulating valves (101), and the first steam generation valve (102), until the tail gas condensation regulating valve (104), the compressor inlet and outlet regulating valves (101), and the first steam generation valve (102) are completely closed; S4: The system enters the stable driving stage.

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