A method for treating wastewater from AC foaming agent production

Abstract

The invention provides a method for treating wastewater from AC foaming agent production, comprising: adding hydrogen peroxide to hydrazine-containing waste liquid, feeding the waste liquid into an ultraviolet catalytic reactor, reacting hydrazine hydrate with hydrogen peroxide to convert them into nitrogen and water under ultraviolet light irradiation to obtain a primary treatment liquid; adding excess cobalt chloride to the primary treatment liquid, adjusting the pH value of the primary treatment liquid to 8, fully stirring the primary treatment liquid, reacting the hydrazine hydrate remaining in the primary treatment liquid with cobalt ions to generate cobalt elemental precipitation and nitrogen, and then filtering to obtain a secondary treatment liquid; the invention can effectively remove hydrazine hydrate in the hydrazine-containing waste liquid through a two-stage treatment process, thereby realizing the treatment of the hydrazine-containing waste liquid.

Description

Technical Field

[0001] The invention relates to the technical field of AC foaming agent production, and in particular to a method for treating AC foaming agent production wastewater. Background Art

[0002] AC foaming agent, scientific name azodicarbonamide, can be used for foaming polyethylene, polyvinyl chloride, polypropylene, polyurethane and various rubbers. It has the characteristics of large gas emission, uniform bubbles, no pollution to products, easy temperature control, etc. It is currently the most widely used high-efficiency foaming agent.

[0003] At present, in the production process of AC foaming agent, such as CN111349022A and CN105859592A, hydrazine hydrate is often prepared by the urea preparation method, the prepared hydrazine hydrate is distilled and refined, the refined hydrazine hydrate, urea and hydrochloric acid are subjected to condensation reaction to generate biurea and ammonium chloride, the product of the condensation reaction is separated to obtain biurea and condensation mother liquor, and then the biurea is subjected to oxidation reaction with chlorine under the catalytic action of a catalyst to generate AC foaming agent and hydrochloric acid, the product of the oxidation reaction is separated to obtain AC foaming agent and oxidation mother liquor. Since the oxidation mother liquor contains hydrochloric acid, a reactant required for the condensation reaction, the prior art often directly reuses the oxidation mother liquor for the condensation reaction.

[0004] Among them, the hydrazine-containing waste liquid generated during the condensation mother liquor and the distillation and refining process of hydrazine hydrate has become the main source of wastewater in the entire AC foaming agent production process. Taking the hydrazine-containing waste liquid as an example, it contains a small amount of hydrazine hydrate, which makes it impossible to discharge directly. Therefore, how to clean the hydrazine-containing waste liquid has become one of the technical problems that need to be solved in this field. Summary of the invention

[0005] In view of this, the present invention aims to provide a method for treating AC foaming agent production wastewater to solve the problem of how to clean hydrazine-containing wastewater in the prior art.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for treating AC foaming agent production wastewater, comprising:

[0008] C1, adding urea, sodium hypochlorite and sodium hydroxide into a hydrazine production reactor to obtain a crude hydrazine hydrate solution;

[0009] C2, putting the crude hydrazine hydrate liquid into a distillation system to obtain refined hydrazine hydrate liquid and hydrazine-containing waste liquid;

[0010] C3, adding refined hydrazine hydrate solution, urea and hydrochloric acid solution into a condensation reactor for condensation reaction, and performing solid-liquid separation on the reactants to obtain biurea and condensation mother liquor;

[0011] C4, taking part of the oxidation mother liquor and mixing it with water and biurea to form a suspension, adding sodium iodide as a catalyst, passing chlorine gas into the suspension to carry out oxidation reaction, and performing solid-liquid separation on the reactants to obtain AC foaming agent and oxidation mother liquor;

[0012] C5, adding hydrogen peroxide to the hydrazine-containing waste liquid in step C2, and then feeding the waste liquid into an ultraviolet photocatalytic reactor, where hydrazine hydrate and hydrogen peroxide are reacted and converted into nitrogen and water under ultraviolet light to obtain a primary treated liquid;

[0013] C6. Add excess cobalt chloride to the primary treatment liquid, adjust the pH of the primary treatment liquid to 8, stir it sufficiently, and allow the remaining hydrazine hydrate in the primary treatment liquid to react with cobalt ions to generate cobalt elemental precipitate and nitrogen, which is then filtered to obtain a secondary treatment liquid.

[0014] Furthermore, in step C5, the molar amount of hydrogen peroxide added to the unit volume of the hydrazine-containing waste liquid is equal to the molar amount of hydrazine hydrate contained in the hydrazine-containing waste liquid.

[0015] Furthermore, in step C6, the molar amount of cobalt chloride added to the unit volume of hydrazine-containing waste liquid is 3-4 times the molar amount of hydrazine hydrate remaining in the primary treatment liquid.

[0016] Furthermore, after step C6, the wastewater treatment method comprises: C7, performing reverse osmosis filtration on the secondary treatment liquid of step C6 to obtain reverse osmosis concentrated liquid and reverse osmosis clear liquid; C8, heating and evaporating the reverse osmosis concentrated liquid to obtain cobalt chloride crystals, condensing the steam generated during the evaporation process, and refluxing the obtained condensate into the hydrazine-containing waste liquid of step C5, or discharging it when it meets the standards; C9, adding sodium hydroxide to the reverse osmosis clear liquid to prepare an alkali solution of the required concentration in step C1, filtering the cobalt hydroxide precipitate generated in the alkali solution, and reusing the filtered alkali solution in step C1.

[0017] Furthermore, the condensate obtained in step C8 is refluxed into the hydrazine-containing waste liquid in step C5.

[0018] Furthermore, the ultraviolet photocatalytic reactor includes a shell having an inner cavity, a first ultraviolet light source is arranged on the inner side wall of the top plate of the shell, a second ultraviolet light source is arranged on the inner side wall of the bottom plate of the shell, a reaction device is arranged between the first ultraviolet light source and the second ultraviolet light source, and the reaction device is respectively connected to the liquid inlet pipeline and the liquid outlet pipeline.

[0019] Furthermore, the reaction device includes a first reaction disk, a second reaction disk, and a connecting pipe, the first reaction disk is located directly above the second reaction disk, the ultraviolet light irradiation direction of the first ultraviolet light source is directly downward toward the first reaction disk, and the ultraviolet light irradiation direction of the second ultraviolet light source is directly upward toward the second reaction disk; the feed port of the first reaction disk is connected to the liquid inlet pipeline, the discharge port of the first reaction disk is connected to the inlet of the connecting pipe, the outlet of the connecting pipe is connected to the feed port of the second reaction disk, and the discharge port of the second reaction disk is connected to the liquid outlet pipeline.

[0020] Furthermore, the hydrochloric acid solution in step C3 is an oxidation mother solution with a hydrochloric acid mass concentration of ≥28%.

[0021] Furthermore, in step C4, 40-50% of the total amount of the oxidation mother liquor obtained in the previous preparation process is used to prepare the suspension.

[0022] Compared with the prior art, the method for treating AC foaming agent production wastewater described in the present invention has the following advantages:

[0023] The method for treating AC foaming agent production wastewater disclosed by the present invention is directed to hydrazine-containing waste liquid generated in the AC foaming agent production process. Through the ultraviolet treatment process of step C5, most of the hydrazine hydrate in the waste liquid can be removed by as clean a treatment as possible. Then, through step C6, excess cobalt chloride is reacted with a small amount of remaining hydrazine hydrate, so that the hydrazine hydrate in the treatment liquid can be completely consumed. Through the two-stage treatment process, the hydrazine hydrate in the hydrazine-containing waste liquid can be effectively removed, thereby realizing the preliminary treatment of the hydrazine-containing waste liquid.

[0024] In addition, after removing hydrazine hydrate from the hydrazine-containing waste liquid through two-stage treatment, the present application further undergoes treatment in steps C7-C9. On the one hand, the cobalt chloride enriched in the concentrated solution is recovered, and the concentrated solution after treatment is recycled to the hydrazine-containing waste liquid in step C5. On the other hand, while preparing the alkali solution through the clear liquid, the trace amount of cobalt chloride remaining in the clear liquid is removed at the same time, and the prepared alkali solution is recycled to the preparation process of hydrazine hydrate in step C1. Therefore, in the entire treatment process of the hydrazine-containing waste liquid, the present application greatly reduces the discharge of wastewater in the production process of hydrazine hydrate, and even does not generate any external drainage in the production process of hydrazine hydrate, thereby realizing the clean treatment of the hydrazine-containing waste liquid in the present application.

[0025] At the same time, due to the recycling of the alkali solution in step C9, a certain amount of solvent (water) is added to the hydrazine hydrate preparation process in step C1, which can greatly reduce the amount of new water required to be added in step C1. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 The following is a simplified diagram of the production process of the AC foaming agent in the present invention;

[0028] Figure 2 is a process flow chart of the distillation system in the present invention;

[0029] Figure 3 It is a partial process flow chart of the distillation system in the present invention;

[0030] Figure 4 A top view of a buffer tank of a distillation system in the present invention;

[0031] Figure 5 for Figure 4 Sectional view along section line AA;

[0032] Figure 6 A top view of a pressure stabilizing component of a distillation system in the present invention;

[0033] Figure 7 for Figure 6 One of the sectional views along section line AA;

[0034] Figure 8 A top view of a buffer substrate of a pressure stabilizing component of a distillation system in the present invention;

[0035] Fig. 9 It is a schematic diagram of the top view of the pressure balance sensing device of the distillation system in the present invention;

[0036] Fig.10 It is a schematic cross-sectional structural diagram of the pressure balance sensing device of the distillation system in the present invention;

[0037] Fig.11 This is one of the structural schematic diagrams of the retractable plug assembly of the distillation system in the present invention;

[0038] Fig.12 This is the second structural schematic diagram of the retractable plug assembly of the distillation system in the present invention;

[0039] Fig.13 for Figure 6 Sectional view 2 along section line AA;

[0040] Fig.14 for Figure 6 Sectional view 3 along section line AA;

[0041] Fig.15 for Figure 6 Sectional view 4 along section line AA;

[0042] Fig.16 It is a schematic structural diagram of the ultraviolet photocatalytic reactor in the present invention;

[0043] Fig.17 It is a schematic diagram of the partial length flow channel structure of the first reaction disk of the ultraviolet photocatalytic reactor in the present invention (top view).

[0044] Description of reference numerals:

[0045] 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 hole; 612. Pressure regulating vent hole; 613. Central support column; 62. Voltage stabilizing regulating plate; 621. Second vent hole; 63. Retractable plug assembly; 631. Plug head; 632. Retractable part; 6321. First retractable body; 6322. Second retractable body; 6323. Third retractable body; 64. Pressure balance sensing device; 641. Central 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. Return Water trough; 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, feed valve; 200, shell; 201, top plate; 202, bottom plate; 203, first ultraviolet light source; 204, second ultraviolet light source; 205, first reaction disk; 206, second reaction disk; 207, connecting pipe; 208, support frame; 209, liquid inlet pipeline; 210, liquid outlet pipeline; 211, first flow channel. DETAILED DESCRIPTION

[0046] The inventive concepts of the present disclosure will be described below using terms commonly used by those skilled in the art to convey the essence of their work to other persons skilled in the art. However, these inventive concepts can be embodied in many different forms and should not be considered limited to the embodiments described herein.

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. The present application includes the treatment of the condensation mother liquor and the treatment of the hydrazine-containing waste liquor, which are described in detail below.

[0049] In order to solve the problem of how to clean the wastewater of condensation mother liquor, this embodiment proposes a method for treating AC foaming agent production wastewater, wherein the name of this application "AC foaming agent production wastewater" can be understood as wastewater generated in the production process of AC foaming agent, and the method comprises:

[0050] B1, adding urea, sodium hypochlorite and sodium hydroxide into a hydrazine production reactor to obtain a crude hydrazine hydrate solution;

[0051] Among them, step B1 adopts the conventional urea method in the prior art to prepare hydrazine hydrate. The specific process content can be directly referred to the prior art, and step B1 does not belong to the main technical solution of this application, so it will not be described here.

[0052] B2, the crude hydrazine hydrate liquid is put into a rectification system to obtain refined hydrazine hydrate liquid and hydrazine-containing waste liquid;

[0053] B3, adding refined hydrazine hydrate solution, urea and hydrochloric acid solution into a condensation kettle for condensation reaction, and performing solid-liquid separation on the reactants to obtain biurea and condensation mother liquor;

[0054] Among them, step B3 adopts the conventional process of preparing biurea from hydrazine hydrate, urea and hydrochloric acid in the prior art. The specific process can refer to the prior art. Of course, the applicant also disclosed the corresponding process content earlier, and this application also maintains the relevant process content, which will not be repeated here.

[0055] It should be noted that the hydrochloric acid solution added to the condensation kettle in step B3 can be a new hydrochloric acid solution or the oxidation mother liquor containing hydrochloric acid in step B4. The present application preferably uses the hydrochloric acid solution added to the condensation kettle in step B3 as the oxidation mother liquor with a hydrochloric acid mass concentration of ≥28%. Of course, if the hydrochloric acid mass concentration in the oxidation mother liquor is lower than 28%, it can be compounded with high-mass concentration hydrochloric acid to meet the hydrochloric acid mass concentration in the oxidation mother liquor of ≥28%. At the same time, the sodium carbonate contained in the refined hydrazine hydrate solution will be converted into sodium chloride in a high acidity environment, which can fully reduce the amount of residual sodium carbonate in the condensation mother liquor.

[0056] B4, taking part of the oxidation mother liquor and water, biurea to prepare a suspension with a biurea content of 250 g / L, and adjusting the pH of the suspension to 2-4, adding sodium iodide catalyst so that the total content of the catalyst in the suspension is 2.8-3.2 g / L, adding the prepared suspension to an oxidation kettle, passing chlorine into the suspension for oxidation reaction, and performing solid-liquid separation on the reactants to obtain AC foaming agent and oxidation mother liquor;

[0057] Among them, for the oxidation mother liquor obtained in step B4 (to be precise, the oxidation mother liquor obtained in the previous preparation process, not the current preparation process), 40-50% of the oxidation mother liquor is reused in step B4 of the current preparation process for preparing the suspension, and the remaining oxidation mother liquor is reused in step B3 for participating in the condensation reaction. Therefore, on the basis of ensuring the normal progress of the conventional condensation reaction, the present application reuses a small part of the oxidation mother liquor in step B4 to prepare the suspension, which can not only reduce the amount of water required for preparing the suspension, but also enables the catalyst in this part of the oxidation mother liquor to be reused in the oxidation reaction, which is conducive to reducing the amount of catalyst added to the suspension each time to reduce the consumption of the catalyst, and accordingly, also reduces the amount of catalyst contained in the condensation mother liquor, and to a certain extent reduces the difficulty of wastewater treatment of the condensation mother liquor, especially refers to the treatment of the catalyst in the wastewater in the wastewater treatment.

[0058] In the oxidation kettle, the reaction temperature is maintained at 25-35°C by continuous stirring to ensure that the oxidation reaction is fully carried out. The reagents used in the pH adjustment process in this application are hydrochloric acid and sodium hydroxide, which are used according to the requirements of the pH environment in each step, so that the sodium chloride formed after neutralization will not cause the introduction of new impurities into the wastewater, ensuring the consistency of the substances in the system.

[0059] Steps B1-B4 of the present application can be regarded as the production stage of AC foaming agent, and reference can be made to the attached Figure 1 At the same time, in addition to the direct treatment of wastewater, this application also pre-treats or controls some substances that may be introduced into the wastewater during the production stage of the AC foaming agent to reduce the difficulty of subsequent wastewater treatment.

[0060] B5. Take the condensation mother liquor of step B3 as wastewater and add it into the flotation equipment, adjust the pH of the wastewater to neutral, add the graphene loaded with iron-based catalyst, stir evenly, heat the wastewater to 80°C, stop heating, add sodium nitrite, and react to remove NH4 contained in the wastewater. + -N, and the solid particulate matter in the wastewater is floated by the nitrogen generated by the reaction, and the solid particulate matter in the wastewater is first-stage deslagging is performed;

[0061] Wherein, in step B5, the ammonium ion contained in the condensation mother liquor is mainly removed by adding sodium nitrite, and nitrogen and water are generated by utilizing ammonium ion and nitrite ion reaction, which contributes to the clean treatment of waste water. Preferably, the amount of the sodium nitrite added is equimolar with the ammonium ion contained in the waste water, that is, in unit volume of waste water, the molar amount of sodium nitrite added is equal to the molar amount of the ammonium ion contained in the waste water. In unit volume of waste water, the added amount of the graphene of the loaded iron-based catalyst is 35-40g / L.

[0062] The iron-based catalyst is iron benzoate. By adding graphene loaded with iron benzoate in step B5, the adsorption performance of graphene is utilized to adsorb and aggregate the ammonium ions and the added nitrite ions in the wastewater, and through the catalytic effect of iron benzoate and the charge conduction effect of graphene, not only can the reaction between the ammonium ions and the nitrite ions be catalyzed, but also the reaction rate of the adsorbed and aggregated ammonium ions and nitrite ions is increased, and the generation rate of nitrogen in a short time is correspondingly increased, which is beneficial to improving the flotation efficiency and flotation treatment efficiency of solid particulate matter in the wastewater. The flotation equipment is commercially available equipment and will not be described in detail.

[0063] For graphene loaded with iron benzoate, the preparation process includes:

[0064] A1. Add graphene to a saturated solution of sodium benzoate, disperse by ultrasonic for 4-5 hours, and then filter to obtain graphene loaded with sodium benzoate, and dry and crush the filter cake;

[0065] A2, adding sodium benzoate-loaded graphene to the ferric chloride solution, stirring and reacting under a hydrothermal treatment condition of 96-98° C. with slight boiling for 40 hours, and filtering to obtain a filter cake of the graphene-loaded iron benzoate;

[0066] In step A2, the ferric chloride solution does not need to be a saturated solution. It is only necessary to ensure that the ferric chloride is in excess relative to the graphene loaded with sodium benzoate, and the two are kept in a stirred and mixed state, and the hydrothermal treatment is carried out in a hydrothermal reactor.

[0067] A3. Wash the filter cake with distilled water and ethanol for 3-5 times respectively, dry, crush and sieve, and take particles with a particle size of 700-900 microns to obtain graphene loaded with iron benzoate for use in step B5.

[0068] Preferably, before the iron benzoate-loaded graphene is used in step B5, the iron benzoate-loaded graphene to be used is first fully dispersed in water to avoid aggregation and clustering between particles, and then the dispersed iron benzoate-loaded graphene is added to the wastewater of step B5 for use to ensure the reaction efficiency and flotation treatment efficiency of step B5.

[0069] The solid particulate matter in the wastewater mainly includes biurea particles, AC foaming agent particles introduced by the oxidation mother liquor, and other solid particulate impurities (such as scale, etc.). The solid particulate matter in the wastewater is first-stage deslagging, and the scum can be directly collected by the scraping device of the flotation equipment, and the collected scum can be separated and removed from the wastewater.

[0070] B6, cooling the wastewater after the first stage of slag removal to room temperature and filtering to filter out the graphene loaded with the iron-based catalyst and the residual solid particulate matter to obtain a filtrate, and adding hydrochloric acid to the filtrate;

[0071] Among them, the filtration process of step B6 can be regarded as the second-stage slag removal of solid particulate matter in the wastewater, and the graphene loaded with iron-based catalyst is also filtered out from the wastewater; the filtration process of step B6 preferably uses a plate and frame filter, and a microporous filter membrane can be used to improve the filtration effect of the wastewater and reduce the solid particulate matter in the wastewater as much as possible.

[0072] In step B6, hydrochloric acid is added to the filtrate to keep the pH of the filtrate at 4-6. On the one hand, it helps to convert a small amount of sodium carbonate that may still remain in the wastewater into sodium chloride. On the other hand, it provides an acidic environment for the removal process of the catalyst contained in the wastewater in step B7.

[0073] B7, maintaining the acidic environment of the filtrate, continuing to add sodium iodate, reacting to remove the catalyst sodium iodide contained in the wastewater, and obtaining iodine-containing waste liquid;

[0074] In step B7, the ratio of the molar amount of sodium iodate added to the molar amount of sodium iodide contained in the wastewater per unit volume is 1: 5. At the same time, in the acidic environment provided by hydrochloric acid, sodium iodate reacts with sodium iodide to generate elemental iodine, water, and sodium chloride, thereby removing the catalyst sodium iodide contained in the wastewater, which helps to achieve clean treatment of the wastewater.

[0075] B8. Add carbon tetrachloride to the iodine-containing waste liquid to extract the iodine element in the iodine-containing waste liquid, and obtain the treated waste liquid after liquid separation.

[0076] Since the amount of catalyst used in the AC foaming agent production process is relatively small, the amount of sodium iodide entering the condensation mother liquor is also relatively small, so that the iodine produced by the reaction of sodium iodate and sodium iodide in step B7 is dispersed in the iodine-containing waste liquid. It is necessary to extract and separate the iodine in step B8 to separate the iodine dispersed in the iodine-containing waste liquid.

[0077] For the treated waste liquid, after adjusting its pH to neutral, the main substance contained therein is sodium chloride, which can be obtained by conventional evaporation precipitation, or the treated waste liquid of the present application can be sent to the chlor-alkali industry for deep treatment, as the electrolyte of the chlor-alkali industry, so that the AC foaming agent-related processes can be used in conjunction with the chlor-alkali industry. Accordingly, steps B5-B8 and adjusting the pH of the treated waste liquid to neutral can be regarded as a treatment process for condensation mother liquor wastewater, and the wastewater treatment method of the present application includes a treatment process for condensation mother liquor wastewater.

[0078] The present application prepares the biurea suspension by reusing part of the oxidation mother liquor during the AC foaming agent production process, which can not only effectively reduce the water consumption in the production stage, but also reduce the total amount of wastewater produced in the production stage to a certain extent, and also reduce the amount of catalyst contained in the condensation mother liquor, thereby reducing the difficulty of wastewater treatment of the condensation mother liquor, especially the treatment of the catalyst in the wastewater during wastewater treatment.

[0079] In the process of treating the condensation mother liquor for wastewater, the present application also completes the two-stage slag removal of solid particulate matter in the process of removing ammonium ions, and then removes the catalyst in an acidic environment to complete the wastewater treatment of the condensation mother liquor. The entire treatment process can effectively remove the ammonium ions, catalysts, suspended solid particulate matter and other substances contained in the condensation mother liquor, while simplifying the wastewater treatment process and improving the wastewater treatment efficiency. In addition, in the relevant reaction process of the present application in wastewater treatment, the salt product after the reaction is completed is mainly sodium chloride, so that the salt contained in the treated wastewater is mainly sodium chloride, avoiding the introduction of other impurities, so as to facilitate the use or treatment of sodium chloride brine by other chemical systems, and also conducive to the clean treatment of the condensation mother liquor wastewater of the present application.

[0080] In the AC foaming agent production stage of steps B1-B4 of the present application, a certain amount of hydrazine-containing waste liquid is generated during the process of obtaining refined hydrazine hydrate liquid by distillation of the distillation system in step B2. The wastewater treatment method of the present application also includes a process for treating the hydrazine-containing waste liquid generated during the distillation process of step B2.

[0081] Specifically, the wastewater treatment method comprises:

[0082] C1, adding urea, sodium hypochlorite and sodium hydroxide into a hydrazine production reactor to obtain a crude hydrazine hydrate solution;

[0083] C2, putting the crude hydrazine hydrate liquid into a distillation system to obtain refined hydrazine hydrate liquid and hydrazine-containing waste liquid;

[0084] C3, adding refined hydrazine hydrate solution, urea and hydrochloric acid solution into a condensation reactor for condensation reaction, and performing solid-liquid separation on the reactants to obtain biurea and condensation mother liquor;

[0085] C4, taking part of the oxidation mother liquor and water, biurea to prepare a suspension with a biurea content of 250 g / L, and adjusting the pH of the suspension to 2-4, adding sodium iodide catalyst so that the total content of the catalyst in the suspension is 2.8-3.2 g / L, adding the prepared suspension to an oxidation kettle, passing chlorine gas into the suspension for oxidation reaction, and performing solid-liquid separation on the reactants to obtain AC foaming agent and oxidation mother liquor;

[0086] Among them, steps C1-C4 are exactly the same as steps B1-B4 in the previous text, which are the production stage of AC foaming agent and will not be repeated here.

[0087] C5, after adding hydrogen peroxide to the hydrazine-containing waste liquid, sending it into an ultraviolet photocatalytic reactor, hydrazine hydrate and hydrogen peroxide are reacted and converted into nitrogen and water under ultraviolet light to obtain a primary treated liquid;

[0088] Wherein, in a unit volume of hydrazine-containing waste liquid, the molar amount of hydrogen peroxide added is equal to the molar amount of hydrazine hydrate contained in the hydrazine-containing waste liquid.

[0089] The hydrogen peroxide that has not completely participated in the reaction will be decomposed into oxygen and water under ultraviolet light, and will not cause additional pollution to the hydrazine-containing waste liquid, which is conducive to the clean treatment of the hydrazine-containing waste liquid in the present application.

[0090] Since the hydrazine-containing waste liquid of the present application is the condensed waste liquid extracted from the top of the tower during the distillation process, the content of hydrazine hydrate in the hydrazine-containing waste liquid is relatively small. Through the ultraviolet treatment process, most of the hydrazine hydrate in the waste liquid can be removed by treating it as cleanly as possible, which is not only beneficial to improving the water treatment efficiency of the primary treatment process, but also helps to reduce the amount of reagents added in the downstream treatment process and reduce the difficulty of treatment.

[0091] The ultraviolet photocatalytic reactor comprises a hydrazine removal reaction section and a decomposition reaction section. In the ultraviolet photocatalytic reactor, hydrazine hydrate and hydrogen peroxide react first in the hydrazine removal reaction section, and then the hydrogen peroxide that does not completely participate in the reaction is decomposed in the decomposition reaction section. Of course, the remaining hydrazine hydrate and hydrogen peroxide can also continue to react in the decomposition reaction section.

[0092] Specifically, as attached Figure 16-17 As shown, the ultraviolet catalytic reactor includes a shell 200 with an inner cavity, a first ultraviolet light source 203 is arranged on the inner wall of the top plate 201 of the shell 200, a second ultraviolet light source 204 is arranged on the inner wall of the bottom plate 202 of the shell 200, a reaction device is arranged between the first ultraviolet light source 203 and the second ultraviolet light source 204, and the reaction device is respectively connected to the liquid inlet pipeline 209 and the liquid outlet pipeline 210, so that the hydrazine-containing waste liquid and hydrogen peroxide enter the reaction device through the liquid inlet pipeline 209, and perform corresponding reactions under the irradiation of ultraviolet light, and the waste liquid after the reaction is discharged from the liquid outlet pipeline 210.

[0093] The reaction device includes a first reaction disk 205, a second reaction disk 206, and a connecting pipe 207. The first reaction disk 205 is located directly above the second reaction disk 206. Accordingly, the ultraviolet light irradiation direction of the first ultraviolet light source 203 is directly downward toward the first reaction disk 205, and the ultraviolet light irradiation direction of the second ultraviolet light source 204 is directly upward toward the second reaction disk 206; the feed port of the first reaction disk 205 is connected to the liquid inlet pipeline 209, the discharge port of the first reaction disk 205 is connected to the inlet of the connecting pipe 207, the outlet of the connecting pipe 207 is connected to the feed port of the second reaction disk 206, and the discharge port of the second reaction disk 206 is connected to the liquid outlet pipeline 210. Therefore, on the basis of satisfying the continuous waste liquid treatment process of performing ultraviolet light catalytic reaction while the waste liquid flows, the ultraviolet light wavelength range of the first ultraviolet light source 203 is 260-280nm, and the ultraviolet light is mainly irradiated to the first reaction disk 205, so that the first reaction disk 205 is used as a hydrazine removal reaction section; the ultraviolet light wavelength range of the second ultraviolet light source 204 is 330-350nm, and the ultraviolet light is mainly irradiated to the second reaction disk 206, so that the second reaction disk 206 is used as a decomposition reaction section.

[0094] The structures of the first reaction disk 205 and the second reaction disk 206 are basically the same, both of which are disk-shaped structures and have a flow channel structure, and the flow channel structure is a plane vortex type; for the convenience of description, the flow channel structure of the first reaction disk 205 is recorded as the first flow channel 211, and the flow channel structure of the second reaction disk 206 is recorded as the second flow channel (not shown); the end of the first flow channel 211 away from the vortex center is the feed port of the first reaction disk 205, and the end of the first flow channel 211 close to the vortex center is the discharge port of the first reaction disk 205; the end of the second flow channel away from the vortex center is the discharge port of the second reaction disk 206, and the end of the second flow channel close to the vortex center is the feed port of the second reaction disk 206. The discharge port of the first reaction disk 205 is located directly above the feed port of the second reaction disk 206, and accordingly, the connecting pipe 207 extends in the vertical direction and connects the discharge port of the first reaction disk 205 and the feed port of the second reaction disk 206 respectively.

[0095] The upper surfaces of the first flow channel 211 and the second flow channel are both open, so that in the reaction device, whether it is the gas generated by the reaction of hydrazine hydrate and hydrogen peroxide, or the gas generated by the decomposition reaction of hydrogen peroxide, it can escape directly from the open structure. Under this open structure, the first reaction disk 205 and the second reaction disk 206 can only be composed of the flow channel structure, and the corresponding structure only has the vortex plate and the corresponding side wall surrounding the flow channel. An external exhaust fan is set at the top of the shell 200 to discharge the gas in the shell 200 to the outside.

[0096] Since the first ultraviolet light source 203 directly irradiates the first reaction disk 205 downward, and the first reaction disk 205 is preferably an open flow channel structure, the first reaction disk 205 can be free of excessive restrictions. However, for the second reaction disk 206, since the second ultraviolet light source 204 irradiates the second reaction disk 206 upward, in order to improve the ultraviolet light irradiation effect, at least the vortex plate of the flow channel structure of the second reaction disk 206 is made of quartz glass, so that the ultraviolet light projected by the second ultraviolet light source 204 to the second reaction disk 206 can penetrate the flow channel structure and irradiate the waste liquid in the flow channel structure with ultraviolet light. Preferably, the flow channel structure of the second reaction disk 206 is made of quartz glass.

[0097] The inner wall of the housing 200 is provided with a carrier 208 for carrying the reaction device. The carrier 208 may be a hollow support plate or a plurality of support arms, which are provided at the lower part of the first reaction disk 205 and / or the second reaction disk 206 to carry them. The carrier 208 may also be a hanging rack to hang the first reaction disk 205 and / or the second reaction disk 206 in the inner cavity of the housing 200.

[0098] C6. Adding excess cobalt chloride to the primary treatment liquid, adjusting the pH of the primary treatment liquid to 8, stirring sufficiently to allow the residual hydrazine hydrate in the primary treatment liquid to react with the cobalt ions to generate cobalt elemental precipitate and nitrogen, and then filtering to obtain a secondary treatment liquid;

[0099] The molar amount of cobalt chloride added to the unit volume of hydrazine-containing waste liquid is 3-4 times the molar amount of hydrazine hydrate remaining in the primary treatment liquid.

[0100] After the primary treatment of step C5, most of the hydrazine hydrate in the waste liquid is removed, and then the excess cobalt chloride reacts with the remaining small amount of hydrazine hydrate, so that the hydrazine hydrate in the treatment liquid can be completely consumed. Accordingly, the secondary treatment liquid can be regarded as wastewater after the treatment of the hydrazine-containing waste liquid, and can be discharged in compliance with the standards after nanofiltration or ion exchange resin treatment. Thus, the present application can effectively remove the hydrazine hydrate in the hydrazine-containing waste liquid through the two-stage treatment process of steps C5-C6, and realize the preliminary treatment of the hydrazine-containing waste liquid.

[0101] However, in order to reduce the amount of wastewater discharged during the production of hydrazine hydrate, or even to eliminate any wastewater discharge during the production of hydrazine hydrate, this is also the main research idea of ​​the applicant in the distillation and wastewater treatment process of hydrazine hydrate production. After step C6, the present application continues to further process the secondary treatment liquid.

[0102] C7, performing reverse osmosis filtration on the secondary treatment liquid to obtain reverse osmosis concentrated liquid and reverse osmosis clear liquid;

[0103] Among them, the reverse osmosis filtration can directly adopt the existing reverse osmosis filtration technology. Accordingly, the volume of the reverse osmosis concentrate is much smaller than the volume of the reverse osmosis clear liquid.

[0104] C8, heating and evaporating the reverse osmosis concentrate to obtain cobalt chloride crystals, condensing the steam generated during the evaporation process, and refluxing the obtained condensate into the hydrazine-containing waste liquid of step C5, or discharging it when it meets the standards;

[0105] Among them, for the reverse osmosis concentrated solution of small volume, at least the excess cobalt chloride in step C6 is enriched, so that by evaporating only the concentrated solution of small volume, not only the cobalt chloride is separated efficiently, the excess cobalt chloride can be recovered, and the waste liquid treatment operation is simplified, the waste liquid treatment difficulty is greatly reduced, and compared with evaporation and crystallization of all secondary treatment liquids, it is beneficial to reduce energy consumption. For the main substance in the evaporated condensate, water can be discharged after meeting the emission standard, or it can be refluxed into the hydrazine-containing waste liquid of step C5 for recycling, so that no external drainage is generated during the treatment of the entire hydrazine-containing waste liquid.

[0106] C9. Add sodium hydroxide to the reverse osmosis clear liquid to prepare an alkali solution of the required concentration in step C1, filter the cobalt hydroxide precipitate generated by the reaction in the alkali solution, and reuse the filtered alkali solution in step C1.

[0107] In the process of adding sodium hydroxide to the reverse osmosis clear liquid to prepare an alkaline solution of the required concentration for preparing hydrazine hydrate, on the one hand, all trace amounts of cobalt chloride contained in the clear liquid are reacted to form cobalt hydroxide precipitates, and the impurity cobalt element in the clear liquid (or alkaline solution) is removed by filtration and separation. On the other hand, the filtrate can be used as the sodium hydroxide solution required in step C1 and directly reused in the preparation process of hydrazine hydrate, so that no external drainage is generated during the treatment process of the entire hydrazine-containing waste liquid.

[0108] Among them, steps C5-C9 can be regarded as a treatment process for hydrazine-containing waste liquid, and accordingly, the wastewater treatment method of the present application includes a treatment process for hydrazine-containing waste liquid. For the entire AC foaming agent production process, in addition to the treatment of the condensation mother liquor wastewater, the present application further cleans the hydrazine-containing waste liquid to achieve comprehensive treatment of wastewater in the entire AC foaming agent production process.

[0109] At the same time, in the process of treating the hydrazine-containing waste liquid, the present application removes the hydrazine hydrate in the hydrazine-containing waste liquid after two-stage treatment, and then undergoes treatment in steps C7-C9. On the one hand, the cobalt chloride enriched in the concentrated solution is recovered, and the concentrated solution after treatment is recycled to the hydrazine-containing waste liquid in step C5. On the other hand, while preparing the alkali solution through the clear liquid, the trace cobalt chloride remaining in the clear liquid is removed at the same time, and the prepared alkali solution is recycled to the preparation process of hydrazine hydrate in step C1. Therefore, in the whole process of treating the hydrazine-containing waste liquid, the present application greatly reduces the discharge of wastewater in the production process of hydrazine hydrate, and even does not generate any external drainage in the production process of hydrazine hydrate. At the same time, due to the reuse of the alkali solution in step C9, a certain amount of solvent (water) is added to the hydrazine hydrate preparation process in step C1, which can greatly reduce the amount of new water required to be added in step C1.

[0110] In addition, for the existing distillation system, the tail gas is often sent to the condenser for forced condensation into condensed water, which not only wastes a lot of heat, but also consumes a lot of water and electricity, increases energy waste, and increases the output of hydrazine-containing waste liquid, which is not conducive to reducing the wastewater treatment load of hydrazine-containing waste liquid, nor is it conducive to reducing the total amount of wastewater produced in the entire AC foaming agent production process, which brings great inconvenience to the wastewater treatment process. In order to solve this problem, the present application improves the distillation system.

[0111] Example 1

[0112] like Figure 2-10 As shown, the distillation system includes a tail gas treatment component and a distillation component. The tail gas treatment component is connected to the distillation component. The distillation component is used to distill and purify crude hydrazine hydrate liquid into refined hydrazine hydrate liquid.

[0113] The distillation assembly comprises a crude hydrazine hydrate liquid conveying pipeline, an evaporation and heating device, a foam trap 4, a distillation tower 5, a cooler 10 and a hydrazine storage tank 11 which are sequentially connected. The evaporation and heating device is used to heat the crude hydrazine hydrate liquid to boil and generate water vapor and hydrazine hydrate vapor azeotropic gas. The evaporation and heating device comprises an evaporator 2 and a heater 3. The foam trap 4 is used to capture mist liquid particles in the water vapor and hydrazine hydrate vapor azeotropic gas coming out of the evaporation and heating device. The hydrazine storage tank 11 is used to store the refined hydrazine hydrate liquid obtained by distillation for use in downstream production processes.

[0114] 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. The tail gas treatment assembly 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. A tail gas condensation regulating valve 104 is provided between the distillation tower 5 and the condenser 12.

[0115] The inlet of the steam compressor 7 is connected to the second outlet pipeline at the top of the distillation tower 5, and the outlet of the steam compressor 7 is connected to the heating pipeline of the evaporation heating device;

[0116] 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. Among them, the absolute pressure of the tail gas evaporated from the distillation tower 5 is about 0.108MPa, and the temperature is about 102°C. The absolute pressure of the high-temperature and high-pressure steam is greater than or equal to 0.4MPa, and the temperature is greater than or equal to 143.6°C. In the present application, the high-temperature and high-pressure steam pressure generated by the steam compressor 7 is 0.4MPa absolute pressure and 143.6°C temperature, which can completely replace the raw steam to heat the crude hydrazine hydrate liquid in the heater 3.

[0117] Specifically, the distillation component also includes a raw steam pipeline, which includes a first branch and a second 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.

[0118] The third flow measurement device is used to detect the flow rate of the raw steam entering the heating pipeline of the heater 3. The fourth flow measurement device is used to detect the flow rate of the raw steam entering the heating pipeline of the tower kettle of the distillation tower 5.

[0119] The distillation component can purify the crude hydrazine hydrate liquid into refined hydrazine hydrate liquid by distillation. Specifically, crude hydrazine hydrate liquid is added to the evaporator 2. When the heater 3 is started up, it is heated by raw steam. After the crude hydrazine hydrate 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 first enter the evaporator 2, and then enter the frother 4. After the mist liquid particles are captured by the frother 4, the hydrazine hydrate enters the distillation tower 5. In the distillation tower 5, the hydrazine hydrate with a higher boiling point flows downward through the lower packing layer to the bottom of the distillation tower 5, and the hydrazine content gradually increases. Finally, it is condensed into a refined hydrazine hydrate liquid with a hydrazine content. The discharge is controlled by the bottom liquid level. Since the high-temperature refined hydrazine hydrate liquid is inflammable, 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 an extremely low hydrazine content. The tail gas at the top 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 0.108 MPa and the temperature is 102°C.

[0120] In the improved distillation system of the present invention, the tail gas treatment component is interconnected with the distillation component, the steam compressor 7, the condenser 12, the reflux water tank 8, the reflux water pump 9, the preheater 1, the steam heating device, the frother 4, the distillation tower 5, the cooler 10 and the hydrazine storage tank 11 are interconnected, the second outlet pipeline at the top of the distillation tower 5 is connected to the steam compressor 7; the steam compressor 7 is connected to the heating pipeline of the evaporation heating device; the arrangement of the steam compressor 7 can compress the tail gas evaporated from the distillation tower 5 into high-temperature and high-pressure steam, and the high-temperature and high-pressure steam from the steam compressor 7 can enter the steam compressor 7. The heating pipe of the evaporation heating device is used as a heating heat source to gradually replace the raw steam to heat the crude hydrazine hydrate liquid in the evaporation heating device, and the liquid crude hydrazine hydrate liquid is converted into water vapor and hydrazine hydrate vapor azeotropic gas and then enters the distillation tower 5. On the one hand, the demand for external energy can be reduced, thereby achieving the effect of saving steam, realizing the recycling of thermal energy, and saving energy and reducing consumption; on the other hand, it can avoid excessive condensation of tail gas into waste water, which can effectively reduce the output of hydrazine-containing waste liquid, reduce the total amount of waste water produced in the entire AC foaming agent production process, and reduce the processing load of the wastewater treatment process.

[0121] 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, the crude hydrazine hydrate liquid 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. Preferably, the foam trap 4 is arranged directly above the evaporator 2.

[0122] 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.

[0123] This arrangement allows the material to be heated and boiled in a circulation between the evaporator 2 and the heater 3, 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, 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, reducing the burden of the foam collector 4, which is beneficial to 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.

[0124] Furthermore, the outlet of the steam compressor 7 is connected to the inlet of the heating pipe of the heater 3. 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 crude hydrazine hydrate liquid in the heater 3, and converting the liquid crude hydrazine hydrate liquid 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 excessive condensation of tail gas into waste water, which can effectively reduce the output of hydrazine-containing waste liquid, reduce the total amount of waste water produced in the entire AC foaming agent production process, and reduce the processing load of the wastewater treatment process.

[0125] The distillation component also includes a preheater 1, which is arranged between the crude hydrazine hydrate liquid delivery pipeline and the evaporator 2. The preheater 1 is used to heat the crude hydrazine hydrate liquid before entering the evaporator 2. A feed valve 105 is arranged between the crude hydrazine hydrate liquid delivery pipeline and the preheater 1.

[0126] Furthermore, the preheater 1 is used to preheat the raw material crude hydrazine hydrate liquid to 55-65°C.

[0127] Furthermore, 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 .

[0128] The high-temperature and high-pressure steam in the heating pipe of the heater 3 heats the crude hydrazine hydrate liquid 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 crude hydrazine hydrate liquid in the preheater 1. On the one hand, it can reduce the demand for external energy and realize the recycling of heat energy to maximize the recovery of heat energy and achieve the effect of energy saving and consumption reduction; on the other hand, it can avoid excessive condensation of tail gas into waste water, which can effectively reduce the output of hydrazine-containing waste liquid, reduce the total amount of waste water produced in the entire AC foaming agent production process, and reduce the processing load of the wastewater treatment process.

[0129] Further, 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 flow-through parts of the reflux water pump 9 are made of 304 stainless steel.

[0130] The temperature of the condensed water from 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 the reflux water at the top of the distillation tower 5. First, it can reduce the demand for external energy, realize the three-fold recycling of thermal energy, so as to maximize the recovery of thermal energy and achieve the effect of energy saving and consumption reduction; second, it can avoid excessive condensation of tail gas into waste water, effectively reduce the output of hydrazine-containing waste liquid, reduce the total amount of waste water produced in the entire AC foaming agent production process, and reduce the processing load of the wastewater treatment process; third, spraying the top of the distillation tower 5 with reflux water can absorb a small amount of residual hydrazine in the tail gas, thereby improving the yield of hydrazine hydrate; fourth, when the reflux water is sprayed, the temperature at the top of the distillation tower 5 is reduced, and the pressure is also reduced, so the system temperature and pressure can be adjusted. Among them, the condensed water flowing into the reflux tank 8 is actually steam from the top of the distillation tower 5, and actually contains a small amount of hydrazine hydrate. In the present application, on the basis of meeting the process requirement of the reflux tank 8 to reflux to the top of the distillation tower 5, the surplus water in the reflux tank 8 can also be sent to the hydrazine-containing waste liquid treatment process of the present application as hydrazine-containing waste liquid.

[0131] like Figure 3 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.

[0132] 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.

[0133] The distillation tower 5 includes a distillation tower body, a tower reactor and a packing layer, and a heating coil is arranged on the tower reactor. This arrangement is conducive to stabilizing the product concentration of the refined hydrazine hydrate solution in the tower reactor, ensuring that the product is qualified and ensuring safe production. The foam catcher 4 is a wire mesh filter made of 304 stainless steel. The evaporator 2 is an empty tank made of 304 stainless steel. The preheater 1, the heater 3, and the cooler 10 are all shell and tube heat exchangers, and the flow parts of the preheater 1, the heater 3, and the cooler 10 are all made of 304 stainless steel.

[0134] During the operation of the distillation tower 5, the stability of the tower top pressure is crucial to maintaining the distillation efficiency, reducing the hydrazine hydrate content in the hydrazine-containing waste liquid, preventing component loss (such as hydrazine escape) and ensuring system safety.

[0135] In order to stabilize the top pressure of the distillation tower 5, Figure 2 As shown, a pressure regulating pipeline 71 is arranged between the inlet pipeline and the outlet pipeline of the steam compressor 7. 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, prevent the hydrazine from escaping due to pressure fluctuations, and is conducive to reducing the hydrazine hydrate content in the hydrazine-containing waste liquid and reducing the difficulty of the wastewater treatment process.

[0136] Specifically, the inlet pipeline of the steam compressor 7 includes a first pipeline 701 and a second pipeline 702 connected, the tail gas enters from the inlet of the first pipeline 701, the first pipeline 701 is vertically arranged, the second pipeline 702 is vertically arranged below the first pipeline 701, and 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, the fifth pipeline 705 is vertically arranged below the fourth pipeline 704, and 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.

[0137] Specifically, Figure 2 As shown, the pressure regulating pipe 71 is arranged horizontally, and the height of the pressure regulating pipe 71 is equal to the height of the fourth pipe 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 smoothness of steam flow and the need for pressure balance.

[0138] One end of the pressure regulating pipe 71 is connected to the first pipe 701, and the other end of the pressure regulating pipe 71 is connected to the third pipe 703 and the fourth pipe 704. This design allows steam to form a circulation or bypass path between the inlet and the outlet, thereby achieving fine adjustment of the system pressure.

[0139] In order to further finely control the stability of the top pressure of the distillation tower 5, the present application sets a compressor inlet and outlet regulating valve 101 on the pressure regulating pipeline 71. Through the opening of the compressor inlet and outlet regulating valve 101, the amount of tail gas entering the pressure regulating pipeline 71 can be adjusted, 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 pipeline 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 pipeline 702, thereby increasing the top pressure. This setting facilitates the pressure regulating pipeline 71 to regulate the stability of the top pressure of the distillation tower 5 through the compressor inlet and outlet regulating valve 101.

[0140] In order to further stabilize the pressure of the system, a buffer tank 6 is arranged between the distillation tower 5 and the steam compressor 7. This arrangement plays a role of buffering and stabilizing pressure, adjusting the system pressure and temperature, and avoiding large fluctuations in the system pressure; on the other hand, it plays a role of gas-liquid separation, preventing liquid in the tail gas from entering the steam compressor 7 and damaging the steam compressor 7.

[0141] 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.

[0142] 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 5-7 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.

[0143] like Figure 5-8 As shown, the voltage stabilizing component 60 includes:

[0144] 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;

[0145] 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;

[0146] 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;

[0147] The pressure balance sensing device 64 is installed at the center position of the bottom of the buffer substrate 61. The pressure balance sensing device 64 is used to sense the balance state of the buffer substrate 61 and 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 ensuring the pressure stability of the system while realizing the exhaust gas recovery and utilization.

[0148] Specifically, Fig.11 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 .

[0149] like Figure 5 and Fig.11 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 .

[0150] like Fig.11 As shown, the telescopic part 632 includes multiple telescopic bodies arranged vertically up and down, and the circuits for triggering the telescopic bodies to telescope are connected in parallel. The number of telescopic bodies included in the telescopic part 632 is not specifically limited.

[0151] In this embodiment, 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.

[0152] 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 .

[0153] Furthermore, 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 .

[0154] Furthermore, in this embodiment, the diameter of the first telescopic body 6321 is equal to the diameter of the plugging part 631 .

[0155] like Figure 5 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.

[0156] When the pressure balance sensing device 64 detects that the buffer substrate 61 is unbalanced due to the uneven impact air pressure, the pressure 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.

[0157] like Figure 9-10 As shown, the pressure balance sensing device 64 includes a center ball 641 located at the center position of the bottom of the buffer substrate 61, a plane 642 supporting the center ball 641, and a sliding resistor 643 arranged along the center ball 641 and the corresponding direction of the retractable plug assembly 63; the sliding resistor 643 includes a sliding part 6431 and a static part 6432, the sliding part 6431 is sleeved on the outside of the static 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 retractable plug assembly 63 to retract. The setting of the pressure balance sensing device 64 can quickly and accurately control the magnitude of the current of the retractable plug assembly 63. Specifically, the number of the sliding resistor 643, the retractable plug assembly 63, and the pressure regulating vent 612 is not specifically limited. In this embodiment, the number of the sliding resistor 643, the retractable plug assembly 63, and the pressure regulating vent hole 612 is preferably five.

[0158] When it is detected that the buffer substrate 61 is unbalanced due to the uneven impact pressure, the pressure 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.

[0159] 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 component. They work together to achieve refined and automated control of the top pressure of the distillation tower 5, while ensuring the efficient recovery and utilization of the exhaust gas, ensuring the stability of the top pressure of the distillation tower 5 and the stable operation of the system, and preventing the hydrazine escape caused by pressure fluctuations, which not only ensures the smooth progress of the distillation process and the overall safety of the system, but also helps to reduce the hydrazine hydrate content in the hydrazine-containing waste liquid and reduce the difficulty of the wastewater treatment process.

[0160] This embodiment also proposes a control method for the distillation system, which is used for the distillation system proposed in this application, and the control method includes the following steps:

[0161] S1, the initial start-up stage, the feed valve 105, the first raw steam valve 102, the second raw steam valve 103, the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 101 are opened, the crude hydrazine hydrate liquid 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 the refined hydrazine hydrate liquid 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;

[0162] Wherein, in step S1, by opening the feed valve 105, the crude hydrazine hydrate liquid is added to the evaporation heating device. At the same time, the tail gas must be produced by raw steam in the initial start-up stage, the first raw steam valve 102 and the second raw steam valve 103 are opened, and the hydrazine hydrate liquid is heated in the evaporation heating device by raw steam to form an azeotropic gas of water vapor and hydrazine hydrate vapor; the azeotropic gas passes through the foam catcher 4 to remove the entrained droplets, and then enters the distillation tower 5 for separation; at the bottom of the distillation tower 5, the refined hydrazine hydrate liquid is collected by the tower kettle; and at the top of the tower, tail gas containing water vapor and a small amount of hydrazine hydrate is generated. Since the tail gas may contain a small amount of air in the initial stage, these tail gases are directly sent to the condenser 12 for condensation treatment when just starting up to avoid safety hazards in the system; after condensation, the hydrazine-containing wastewater is diverted, a small part enters the reflux tank 8 for recycling, and the rest is sent to the treatment process of the hydrazine-containing wastewater of the present application.

[0163] 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;

[0164] Step S2 is set to determine whether there is still air in the system, which is to ensure that the subsequent stage can safely switch to using the steam compressor 7 to treat the exhaust gas, avoid air from causing damage to the steam compressor 7, and ensure system safety.

[0165] S3, entering the conversion start-up phase, gradually closing the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 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 valve 101, and the first steam generation valve 102 are completely closed;

[0166] After confirming that there is no air in the system, start to gradually adjust the opening of the tail gas condensation regulating valve 104, the compressor inlet and outlet regulating valve 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 level of the evaporator 2 and the temperature of the heater 3 to ensure a smooth transition of the system.

[0167] S4: The system enters the stable driving stage.

[0168] After closing the relevant valves, the system enters step S4 and enters the stable start-up phase. 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, but also ensures that the tail gas is effectively treated and the energy therein is recycled.

[0169] The control method of the distillation system proposed in the present application, steps S1-S4 are interrelated, and 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 while achieving a high recovery rate of the tail gas, which not only ensures the smooth progress of the distillation process and the overall safety of the system, but also helps to reduce the hydrazine hydrate content in the hydrazine-containing waste liquid and reduce the difficulty of the wastewater treatment process.

[0170] 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.

[0171] 1. 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, and the three-level utilization of the tail gas of the distillation tower 5 is realized, which not only greatly reduces the demand for external energy, but also recovers heat energy to the maximum extent, achieves the effect of energy saving and consumption reduction, and realizes a high recovery rate of the tail gas; it can also avoid excessive condensation of the tail gas into waste water, which can effectively reduce the output of hydrazine-containing waste liquid, reduce the total amount of waste water produced in the entire AC foaming agent production process, and reduce the processing load of the wastewater treatment process; the reflux water spraying at the top of the distillation tower 5 can absorb a small amount of residual hydrazine in the tail gas on the one hand, and control the hydrazine content in the unit volume of the hydrazine-containing waste liquid to below 0.1g / L; on the other hand, it can accurately control the top temperature of the distillation tower 5, and prevent the phenomenon of hydrazine in the tail gas caused by temperature fluctuations, which is conducive to further reducing the hydrazine hydrate content in the hydrazine-containing waste liquid and reducing the processing difficulty of the wastewater treatment process.

[0172] 2. 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 tail gas treatment component. 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 tail gas, and preventing the hydrazine escape caused by pressure fluctuations, which not only ensures the smooth progress of the distillation process and the overall safety of the system, but also helps to reduce the hydrazine hydrate content in the hydrazine-containing waste liquid and reduce the difficulty of the wastewater treatment process.

[0173] 3. During the initial start-up phase, the tail gas condensation regulating valve 104 is opened, and the tail gas is directly sent into the condenser 12, which can drive away the air in the system and ensure the safety of the system.

[0174] 4. During the transition 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. During 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, and also helping to reduce the output of hydrazine-containing waste liquid and reduce the wastewater treatment load on the hydrazine-containing waste liquid.

[0175] 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 .

[0176] A first temperature sensor is provided in the heater 3, and the first temperature sensor is used to detect the temperature in the heater 3. An oxygen detector, a first pressure sensor, and a second temperature sensor are provided at the top of the distillation tower 5, and 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.

[0177] A third temperature sensor, a second pressure sensor and a first flow measurement device are provided at the inlet of the steam compressor 7. 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.

[0178] A fourth temperature sensor, a third pressure sensor and a second flow measurement device are provided at the inlet of the steam compressor 7. The fourth temperature sensor is used to detect the temperature at the outlet of the steam compressor 7; the third pressure sensor is used to detect the pressure at 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.

[0179] Specifically, step S31 includes the following steps:

[0180] S31, the reflux water pump 9 is started, and the first reflux water valve 1311 and the second reflux water valve 1321 are opened;

[0181] S32, the opening of the tail gas condensation regulating valve 104 is reduced;

[0182] Specifically, the amount by which the tail gas condensation regulating valve 104 is adjusted down is not specifically limited. In this embodiment, the amount by which the tail gas condensation regulating valve 104 is adjusted down is 1 / 5 of the fully open state.

[0183] 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;

[0184] 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.

[0185] S34, entering the first step-down regulation mode.

[0186] S35, judging whether P satisfies P<preset pressure P0, if so, proceeding to step S36; if not, maintaining the original operation state;

[0187] S36, entering the first boost regulation mode.

[0188] 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 feed valve 105 remains unchanged, and return to step S32; if not, return to step S37 (or re-execute step S37).

[0189] 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.

[0190] Steps S31 to S38 are interrelated. The distillation system control method of this embodiment achieves a high recovery rate of tail gas and effective recovery and utilization of energy, ensures the smooth progress of the distillation process and the overall safety of the system, and is also beneficial to reducing the hydrazine hydrate content in the hydrazine-containing waste liquid and reducing the difficulty of the wastewater treatment process.

[0191] Specifically, step S34 includes the following steps:

[0192] 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.

[0193] 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.

[0194] S342, entering the voltage reduction and temperature unchanged regulation mode;

[0195] S343, determine whether T satisfies T<preset temperature T0, if yes, proceed to step S344, if no, proceed to step S345;

[0196] S344, entering the voltage reduction and temperature increase regulation mode;

[0197] S345, entering the voltage reduction and temperature reduction regulation mode.

[0198] Specifically, step S342 includes the following steps:

[0199] 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;

[0200] 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 .

[0201] 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;

[0202] S3423, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3424, if not, proceed to step S3425;

[0203] 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 reflux water valve 1331 is opened, and the feed valve 105 is opened to a larger opening;

[0204] S3425, 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 reflux water valve 1331 is opened, and the feed valve 105 is opened to a smaller opening.

[0205] Specifically, step S344 includes the following steps:

[0206] 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;

[0207] 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;

[0208] 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 .

[0209] S3443, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3444, if not, proceed to step S3445;

[0210] 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 reflux water valve 1331 is opened, the operating frequency of the steam compressor 7 is increased, and the feed valve 105 is opened to a larger opening;

[0211] 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 feed valve 105 is opened to a smaller opening.

[0212] Specifically, step S345 includes the following steps:

[0213] 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;

[0214] 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;

[0215] S3453, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3454, if not, proceed to step S3455;

[0216] 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 reflux water valve 1331, reduce the opening of the first steam valve 102, and increase the opening of the feed valve 105;

[0217] 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 feed valve 105.

[0218] Specifically, step S36 includes the following steps:

[0219] 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.

[0220] S362, entering the voltage-boosting and temperature-unchanged regulation mode;

[0221] S363, determine whether T satisfies T<preset temperature T0, if yes, proceed to step S364, if no, proceed to step S365;

[0222] S364, entering the boost and temperature regulation mode;

[0223] S365, enter the boost and temperature reduction regulation mode.

[0224] Specifically, step S362 includes the following steps:

[0225] 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;

[0226] 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;

[0227] S3623, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3624, if not, proceed to step S3625;

[0228] S3624, enter the pressure-boosting and temperature-unchanged liquid level regulating mode, increase the opening of the compressor inlet and outlet regulating valves 101, close the third return water valve 1331, open the third return water valve 1331, and increase the opening of the feed valve 105;

[0229] 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 feed valve 105.

[0230] Specifically, step S364 includes the following steps:

[0231] 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;

[0232] 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;

[0233] S3643, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3644, if not, proceed to step S3645;

[0234] 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 feed valve 105 is opened wider;

[0235] 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 feed valve 105.

[0236] Specifically, step S365 includes the following steps:

[0237] 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;

[0238] 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;

[0239] S3653, determine whether R satisfies R<preset material liquid level R0, if so, proceed to step S3654, if not, proceed to step S3655;

[0240] S3654, enter the pressure increase, temperature decrease 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 feed valve 105 is opened wider;

[0241] S3655, enter the pressure increase, temperature decrease 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, decrease the opening of the first steam valve 102, and decrease the opening of the feed valve 105.

[0242] This series of steps S34, S36 specific control process, and its sub-steps S342, S344, S345, S362, S364, S365 specific control process, show the specific parameter adjustment and mode switching in the distillation system control process, aiming to achieve efficient recovery of tail gas and effective utilization of energy through fine control. Each step is based on real-time monitoring of system parameters, and dynamically adjusted according to preset conditions and target values ​​to ensure the safety, stability and efficiency of the entire distillation system control process.

[0243] Specifically, step S4 includes the following steps:

[0244] 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;

[0245] 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;

[0246] S43, judging whether P satisfies P<preset pressure P0, if so, proceeding to step S44; if not, maintaining the current operating state;

[0247] 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.

[0248] When the system is ready to shut down, in order to ensure the safe production of the distillation components, open the tail gas condensation regulating valve 104, gradually increase the opening of the tail gas condensation regulating valve 104, and then gradually increase the opening of the compressor inlet and outlet regulating valve 101. 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, turn off the steam compressor 7 to ensure the steady drop of the pressure of the distillation tower 5.

[0249] 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 refined hydrazine hydrate liquid 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 refined hydrazine hydrate liquid 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 electricity fee of 280*0.6 / 2=84 yuan is required to increase the electricity fee of 1 ton of refined hydrazine hydrate liquid.

[0250] Based on the above calculations, after recycling the tail gas, the cost of producing each ton of refined hydrazine hydrate liquid can be saved by 520-84=436 yuan. The energy-saving effect is still very significant.

[0251] Example 2

[0252] In this embodiment, different from the embodiment 1, Figure 12-15 As shown, the diameter of the blocking part 631 is smaller than the diameter of the first telescopic body 6321; the diameter of the first telescopic body 6321 is smaller than the diameter of the second telescopic body 6322; the diameter of the second telescopic body 6322 is smaller than the diameter of the third telescopic body 6323; and the diameter of the third telescopic body 6323 is smaller than the diameter of the pressure regulating vent hole 612.

[0253] 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.

[0254] When the pressure balance sensing device 64 detects that the buffer substrate 61 is unbalanced due to the uneven impact air pressure, the pressure balance sensing device 64 adjusts the current that triggers the extension and contraction 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.

[0255] Example 3

[0256] In this embodiment, different from the embodiment 1, Fig.15 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 .

[0257] 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 .

[0258] 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 .

[0259] The pressure difference of the exhaust gas from the air inlet of the buffer tank 6 to the buffer substrate 61 is P2-P1.

[0260] 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;

[0261] 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.

[0262] 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.

[0263] 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.

[0264] Regarding the treatment effect of ammonium ions, catalyst sodium iodide, solid particulate matter and other substances contained in the condensation mother liquor, on the basis of the AC foaming agent production process of steps B1-B4 of the present application, the applicant took the condensation mother liquor of a certain intermediate batch production process in the multi-batch production of AC foaming agent, and divided it into four parts with the same volume as four parts of wastewater, which were respectively recorded as blank example, experimental example, comparative example 1, and comparative example 2.

[0265] Blank example

[0266] No treatment is performed on the wastewater.

[0267] Experimental example

[0268] The processing process of steps B5-B8 recorded in this application specifically includes:

[0269] The wastewater is added to the flotation equipment, the pH value of the wastewater is adjusted to neutral, 40g / L of graphene loaded with iron benzoate is added, and after being stirred evenly, the wastewater is heated to 80°C and the heating is stopped, and sodium nitrite in an amount equimolar to the ammonium ions is added to react and remove the ammonium ions contained in the wastewater, and the solid particulate matter in the wastewater is floated by the nitrogen generated by the reaction, and the solid particulate matter in the wastewater is first-stage deslagging is performed; the wastewater after the first-stage deslagging is cooled to room temperature and filtered to filter out the graphene loaded with the iron-based catalyst and the residual solid particulate matter to obtain a filtrate, hydrochloric acid is added to the filtrate to keep the pH value of the filtrate at 4-6, sodium iodate is added to the filtrate, and the ratio of the molar amount of the added sodium iodate to the molar amount of the sodium iodide contained in the wastewater is 1:5, and the catalyst sodium iodide contained in the wastewater is removed by reaction to obtain an iodine-containing waste liquid; carbon tetrachloride is added to the iodine-containing waste liquid to extract the iodine element in the iodine-containing waste liquid, and the treated wastewater is obtained after liquid separation.

[0270] Comparative Example 1

[0271] The operation of Comparative Example 1 is exactly the same as that of the experimental example, the only difference being that graphene loaded with iron benzoate is not added in Comparative Example 1.

[0272] Comparative Example 2

[0273] The treatment technology of condensation mother liquor wastewater using the existing technology of using slaked lime stripping process combined with flocculation precipitation process is adopted, specifically: adding slaked lime to the wastewater, adjusting the pH to 10-12, and stripping with an air pump for 4 hours. Add 0.6g / L of polyaluminium chloride and 0.020g / L of polyacrylamide to the water body after stripping, perform flocculation precipitation, filter the wastewater after flocculation precipitation, and obtain treated waste liquid.

[0274] Conventional analysis and detection were performed on the ammonium ions, iodide ions and solid particulate matter contained in the wastewater of the blank example, the wastewater after the experimental example treatment, and the wastewater after the comparative examples 1 and 2 treatment. The specific test results are shown in Table 1.

[0275] Table 1 Detection results of ammonium ions, iodide ions and solid particulate matter in water based on unit volume of wastewater

[0276]

[0277] From Table 1 we can see that:

[0278] Compared with the stripping ammonium removal process in the prior art, the present application adds sodium nitrite to the wastewater under the action of graphene loaded with iron benzoate through step B5, which can effectively remove ammonium ions, and the ammonium ions contained in the wastewater after the experimental example is treated are significantly less than the ammonium ions contained in the wastewater after the comparative example 2 is treated, and it is statistically significant (p < 0.01). At the same time, comparing the experimental example with the comparative example 1, it can be seen that the effect of removing ammonium ions in the experimental example under the action of graphene loaded with iron benzoate is better than the effect of removing ammonium ions in the comparative example 1, and it is statistically significant (p < 0.01).

[0279] Since the catalyst contained in the condensation mother liquor wastewater is often not removed during the treatment process in the prior art, the present application focuses on how to remove the catalyst sodium iodide used in the present application, and the iodide ions can be effectively removed through steps B7-B8, while comparative example 2 obviously does not remove the sodium iodide.

[0280] In addition, with regard to the removal effect of solid particulate matter, the results of the experimental example are slightly worse than those of comparative example 2. After preliminary analysis by the applicant, it is believed that this is, to a certain extent, due to the fact that in the operation process of steps B5 and B6 related to the removal of ammonium ions, the present application synergistically performs two-stage slag removal. The original intention of the applicant for this technical improvement is to simplify the wastewater treatment process and improve the wastewater treatment efficiency.

[0281] Although the deslagging result of the experimental example is slightly worse than that of the comparative example 2 compared with the "separate deslagging process" such as adding flocculants to deslagging in the prior art, the difference between the two is not large, and the deslagging result of the present application is also <1.0g / L, which is also the treatment index of solid particulate matter in wastewater that the applicant expects to achieve in the early stage of research and development. At the same time, by comparing the experimental example with comparative example 1, it can be seen that in the treatment process of step B5 of the present application, the nitrogen generation rate in a short time is increased under the action of graphene loaded with iron benzoate, which helps to improve the flotation effect of solid particulate matter in wastewater, which also makes the deslagging effect of the experimental example better than that of comparative example 1, and has statistical significance (p < 0.01).

[0282] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating AC foaming agent production wastewater, characterized in that: The processing method comprises: C1, adding urea, sodium hypochlorite and sodium hydroxide into a hydrazine production reactor to obtain a crude hydrazine hydrate solution; C2, putting the crude hydrazine hydrate liquid into a distillation system to obtain refined hydrazine hydrate liquid and hydrazine-containing waste liquid; C3, adding refined hydrazine hydrate solution, urea and hydrochloric acid solution into a condensation reactor for condensation reaction, and performing solid-liquid separation on the reactants to obtain biurea and condensation mother liquor; C4, taking part of the oxidation mother liquor and mixing it with water and biurea to form a suspension, adding sodium iodide as a catalyst, passing chlorine gas into the suspension to carry out oxidation reaction, and performing solid-liquid separation on the reactants to obtain AC foaming agent and oxidation mother liquor; C5, adding hydrogen peroxide to the hydrazine-containing waste liquid in step C2, and then feeding the waste liquid into an ultraviolet photocatalytic reactor, where hydrazine hydrate and hydrogen peroxide are reacted and converted into nitrogen and water under ultraviolet light to obtain a primary treated liquid; C6. Adding excess cobalt chloride to the primary treatment liquid, adjusting the pH of the primary treatment liquid to 8, stirring sufficiently to allow the residual hydrazine hydrate in the primary treatment liquid to react with the cobalt ions to generate cobalt elemental precipitate and nitrogen, and then filtering to obtain a secondary treatment liquid; The treatment method includes a treatment process for the condensation mother liquor in step C3, and the treatment process for the condensation mother liquor includes: C31, the condensation mother liquor is recorded as wastewater and added into the flotation equipment, the pH of the wastewater is adjusted to neutral, the graphene loaded with iron-based catalyst is added, and after being stirred evenly, the wastewater is heated to 80° C. and the heating is stopped, sodium nitrite is added, the ammonium ions contained in the wastewater are removed by reaction, and the solid particulate matter in the wastewater is floated by the nitrogen generated by the reaction, and the solid particulate matter in the wastewater is subjected to the first stage of slag removal; C32, cooling the wastewater after the first stage of slag removal to room temperature and filtering to filter out the graphene loaded with the iron-based catalyst and the residual solid particulate matter to obtain a filtrate, and adding hydrochloric acid to the filtrate; C33, maintaining the acidic environment of the filtrate, continuing to add sodium iodate, reacting to remove the catalyst sodium iodide contained in the wastewater, and obtaining iodine-containing waste liquid; C34, adding carbon tetrachloride to the iodine-containing waste liquid to extract the iodine element in the iodine-containing waste liquid, separating the liquids to obtain treated waste liquid, and then adjusting the pH of the treated waste liquid to neutral; In step C31, the molar amount of sodium nitrite added per unit volume of wastewater is equal to the molar amount of ammonium ions contained in the wastewater, the graphene loaded with an iron-based catalyst is graphene loaded with iron benzoate, and the amount of the graphene loaded with an iron-based catalyst added per unit volume of wastewater is 35-40 g / L.

2. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: In step C5, the molar amount of hydrogen peroxide added to the unit volume of the hydrazine-containing waste liquid is equal to the molar amount of hydrazine hydrate contained in the hydrazine-containing waste liquid.

3. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: In step C6, the molar amount of cobalt chloride added to the unit volume of hydrazine-containing waste liquid is 3-4 times the molar amount of hydrazine hydrate remaining in the primary treatment liquid.

4. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: After step C6, the processing method includes: C7, performing reverse osmosis filtration on the secondary treated liquid of step C6 to obtain reverse osmosis concentrated liquid and reverse osmosis clear liquid; C8, heating and evaporating the reverse osmosis concentrate to obtain cobalt chloride crystals, condensing the steam generated during the evaporation process, and refluxing the obtained condensate into the hydrazine-containing waste liquid of step C5; C9. Add sodium hydroxide to the reverse osmosis clear liquid to prepare an alkali solution of the required concentration in step C1, filter the cobalt hydroxide precipitate generated in the alkali solution, and reuse the filtered alkali solution in step C1.

5. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: The ultraviolet catalytic reactor comprises a shell (200) having an inner cavity, a first ultraviolet light source (203) is arranged on the inner side wall of a top plate (201) of the shell (200), a second ultraviolet light source (204) is arranged on the inner side wall of a bottom plate (202) of the shell (200), a reaction device is arranged between the first ultraviolet light source (203) and the second ultraviolet light source (204), and the reaction device is respectively connected to a liquid inlet pipeline (209) and a liquid outlet pipeline (210).

6. The method for treating AC foaming agent production wastewater according to claim 5, characterized in that: The reaction device comprises a first reaction disk (205), a second reaction disk (206), and a connecting pipe (207); the first reaction disk (205) is located directly above the second reaction disk (206); the ultraviolet light irradiation direction of the first ultraviolet light source (203) is directly downward toward the first reaction disk (205); the ultraviolet light irradiation direction of the second ultraviolet light source (204) is directly upward toward the second reaction disk (206); the feed port of the first reaction disk (205) is connected to a liquid feed pipeline (209); the discharge port of the first reaction disk (205) is connected to an inlet of the connecting pipe (207); the outlet of the connecting pipe (207) is connected to the feed port of the second reaction disk (206); and the discharge port of the second reaction disk (206) is connected to a liquid discharge pipeline (210).

7. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: The hydrochloric acid solution in step C3 is an oxidation mother solution with a hydrochloric acid mass concentration of ≥28%.

8. The method for treating AC foaming agent production wastewater according to claim 1, characterized in that: In step C4, 40-50% of the total amount of the oxidation mother solution obtained in the previous preparation process is used to prepare the suspension.

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