A system for recovering and purifying working fluid in regenerated wastewater

Abstract

The present invention provides a system for recovering and purifying working fluid in regenerated wastewater, comprising a regenerated wastewater tank for storing regenerated wastewater generated in hydrogen peroxide production; a regenerated wastewater separator, the regenerated wastewater separator being connected to the regenerated wastewater tank; a phosphoric acid high-level tank, arranged at the upstream side of the regenerated wastewater separator, for adding phosphoric acid to the regenerated wastewater entering the regenerated wastewater separator; a filter assembly, the filter assembly being connected to the regenerated wastewater separator; and a regeneration device, the regeneration device being connected to the filter assembly. The present invention effectively recovers and obtains relatively clean working fluid from regenerated wastewater in an emulsified state composed of a large amount of sewage, alumina powder or catalyst powder, and working fluid degradation products by means of demulsification, static separation, and multi-stage filtration, so as to reduce the risk of further emulsification when subsequently mixed with caustic soda, and improve the cleanliness and reuse rate of the working fluid when it is recovered.

Description

Technical Field

[0001] The invention relates to the technical field of producing hydrogen peroxide by an anthraquinone process, and in particular to a system for recovering and purifying a working fluid in regenerated wastewater. Background Art

[0002] When hydrogen peroxide (chemical formula: H2O2) is produced by the anthraquinone method, the activity of the catalyst decreases due to adsorption of degradation products or other impurities, and steam is needed for regeneration. In addition, the hydrogenated clay bed and post-treatment clay bed used to regenerate the working fluid degradation products and adsorb the working fluid impurities also need to be regenerated by steam to desorb the working fluid adsorbed in its pores after the activated alumina filled in them fails. The regeneration of catalysts and clay beds will produce a large amount of regeneration wastewater. A single regeneration of the hydrogenation tower or clay bed of a 200,000 tons / year hydrogen peroxide production unit can produce at least 80m 3 Recycled wastewater, and the working fluid content can reach 5-10m 3 Since there are a lot of alumina powder or catalyst powder, organic degradation products and other impurities in the regeneration wastewater, they are often mixed with the working fluid in an emulsified state and difficult to separate. How to cleanly and effectively recover the working fluid from the regeneration wastewater has become a technical problem in this field.

[0003] To this end, Chinese patent application number 201410693371.2 discloses a method for treating wastewater in the hydrogen peroxide industry, wherein the wastewater is divided into three parts, wherein the upper working liquid is directly recovered, the oil flocculants in the middle layer are heated, then alkali is added and stirred for stratification to recover the upper working liquid, and the lower sewage is firstly added with phosphoric acid to adjust the pH, then a flocculant is added for flocculation and allowed to stand for stratification, and the upper flocculated waste residue is incorporated into the oil flocculants for treatment. This scheme requires two phases to be treated separately, the operation is cumbersome and requires a large amount of chemical reagents, and the COD of the wastewater is finally reduced to less than 3000 mg / L, the recovery rate of the working liquid is low and the sewage treatment pressure is high. The Chinese patent with application number 201811462216.4 discloses a method for pre-treating wastewater in the production of hydrogen peroxide by the anthraquinone method. First, by adding flocculants and blowing air into the sewage pool, the working fluid and solid particles in the sewage are separated in the form of floccules, reducing the organic matter content and suspended solids (SS) in the sewage, and reducing the COD and suspended solids content of the sewage; the floccules are extracted with heavy aromatic hydrocarbons, and then transferred to a solid filter press for filtration. After filtration, the liquid is allowed to stand and stratify to obtain a recovered working fluid. This method can reduce the oil content in the sewage by more than 80% and the COD to below 1500 mg / L. Since heavy aromatic hydrocarbons are a mixture, this method will change the composition of the working fluid and make it difficult to recycle. How to improve the cleanliness and recovery rate of the recovered working fluid is crucial to reducing the difficulty of treating the wastewater itself and achieving green production.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The problem solved by the invention is that the recovery rate of working liquid in wastewater produced by the existing anthraquinone method for producing hydrogen peroxide is low and the wastewater treatment is difficult, which is not conducive to realizing green production.

[0006] This company provides a system for recovering and purifying the working fluid in the regenerated wastewater, including:

[0007] A regeneration wastewater tank for storing regeneration wastewater generated in the production of hydrogen peroxide;

[0008] A regeneration wastewater separator, the regeneration wastewater separator is connected to the regeneration wastewater tank, a sewage discharge pipe is arranged at the bottom of the regeneration wastewater separator, a vent pipe is arranged at the top of the regeneration wastewater separator, and a flame arrester is arranged in the vent pipe;

[0009] A phosphoric acid high-level tank is arranged at the upstream side of the regeneration wastewater separator and is used to add phosphoric acid to the regeneration wastewater entering the regeneration wastewater separator;

[0010] A filter assembly connected to the regenerated wastewater separator;

[0011] A regeneration device, wherein the regeneration device is connected to the filtering component, the regeneration device is provided with a heating component and a stirring component, the top of the regeneration device is respectively connected to a phosphoric acid pipeline, a caustic soda pipeline, and a tap water pipeline, and the bottom of the regeneration device is provided with a drain port;

[0012] Use the following method:

[0013] Step S1: transporting the regenerated wastewater in the regenerated wastewater tank to the regenerated wastewater separator, and at the same time transporting the phosphoric acid solution with a mass concentration of 54-60% in the high-level phosphoric acid tank to the regenerated wastewater separator according to a volume ratio of 1:200-1:1000, stirring for 20-40 minutes and then standing for separation;

[0014] Step S2: After the working fluid in the upper layer passes through the filter assembly, it is transported to the regeneration equipment for regeneration treatment; the regeneration treatment includes:

[0015] Step S21: transport the filtrate to the regeneration equipment, add pure water into the equipment at a volume ratio of 1:10-3:20, then add a phosphoric acid solution with a mass concentration of 53-60% into the regeneration equipment at a volume ratio of 1:200-3:2000, stir for 10-15 minutes, let stand for 2-4 hours, and discard the pickling wastewater at the bottom layer;

[0016] Step S22: adding a caustic soda solution with a mass concentration of 5-15% into the regeneration equipment at a volume ratio of 1:10-1:100, stirring for 10-15 minutes and then standing for 3-6 hours, and discarding the alkali washing regeneration wastewater at the bottom layer;

[0017] Step S23: pure water was added into the regeneration device at a volume ratio of 1:10, and then phosphoric acid solution was added at a volume ratio of 1:200, and the final pH was adjusted to 7.0. After stirring for 10 minutes, the mixture was allowed to stand for 4 hours, and the upper working solution was collected.

[0018] Step S3: Dry and remove water from the working liquid collected in step S23.

[0019] Preferably, the regeneration wastewater tank is connected to the regeneration wastewater separator via a regeneration wastewater inlet pipe, a regeneration wastewater pump is provided on the regeneration wastewater inlet pipe, and the phosphoric acid high-level tank adds phosphoric acid to the upstream side of the regeneration wastewater pump.

[0020] Preferably, the filter assembly includes a primary filter and a secondary filter arranged in series, the liquid inlet of the primary filter is connected to the regenerated wastewater separator through a recovery liquid discharge pipe, the liquid outlet of the secondary filter is connected to the regeneration equipment, the filter element accuracy of the primary filter is 1-10μm, and the filter element accuracy of the secondary filter is 0.5~1μm.

[0021] Preferably, a pure water spray pipe is provided on the top of the inner wall of the regenerated wastewater separator, and the pure water spray pipe is used to spray pure water into the regenerated wastewater separator for cleaning.

[0022] Preferably, the regenerated wastewater separator is provided with an interface meter, which is used to monitor the interface height between the sewage and the recovered working fluid in the regenerated wastewater separator; the regenerated wastewater separator is also provided with a liquid level meter, which is used to monitor the upper interface liquid level of the recovered working fluid.

[0023] Preferably, a sight glass and a valve are provided on the sewage discharge pipe, the valve is arranged on the downstream side of the sight glass, and the sight glass is used to observe the discharge of sewage to avoid accidental discharge of working fluid.

[0024] Preferably, an overflow pipe is provided at the upper part or near the top of the regeneration wastewater separator, and the overflow pipe is connected to the regeneration wastewater tank.

[0025] Preferably, the system for recovering the working fluid in the regenerated wastewater also includes a filtering device and a standing tank which are sequentially arranged on the sewage discharge pipe, the filtering device is located on the downstream side of the sight glass, the top of the standing tank is conical and is connected to the recovery liquid discharge pipe, and is used to recover the working fluid in the standing tank; the system for recovering the working fluid in the regenerated wastewater also includes a filter aid mixing tank, the liquid inlet and the liquid discharge port of the filter aid tank are respectively connected to the water adding pipeline, and are used to add the filter aid to the regenerated wastewater separator after adding water.

[0026] Preferably, the system for recovering the working fluid in the regenerated wastewater also includes a mixing device and a separation tank, which are sequentially arranged on the sewage discharge pipe. The mixing device is located on the downstream side of the static tank. The top of the separation tank is conical and connected to the recovery liquid discharge pipe, so as to recover the working fluid in the separation tank.

[0027] The temperature of the filtrate in step S21 is 50-65°C.

[0028] Preferably, step S3 also includes step S23: adding pure water to the working solution after alkali washing at a volume ratio of 1:10-3:20, and then adding phosphoric acid solution at a volume ratio of 1:100-1:200, adjusting the final pH to 6.5-7.0, stirring for 10-20 minutes and then standing for 4-7 hours, and collecting the working solution and the second acid washing wastewater respectively.

[0029] Preferably, the residual liquid is treated as follows: after stirring the residual liquid at a speed of 500-1000 rpm for 20-40 min, modified perlite is added at a w / v ratio of 0.5-0.8% for filtration, and after standing for 0.5-1 h, the second working liquid on the upper layer and the lower aqueous phase are collected respectively, and the second working liquid is combined with the first working liquid and then enters step S2 for treatment.

[0030] Preferably, the modified perlite is prepared by the following method: step S11: heating n-eicosane to 40-42°C, adding linseed oil at a volume ratio of 1.9:1-2.4:1 and stirring for 20-25 minutes until the mixture is uniformly mixed; step S12: adding naphtha at a volume ratio of 1:2-1:4 and stirring for 15 minutes until the mixture is uniformly mixed; step S13: adding perlite and stirring evenly, wherein the volume ratio of perlite to naphtha is 1:2.5-1:3.5, and drying at 140°C for 30 minutes to obtain the modified perlite.

[0031] Preferably, the lower aqueous phase is treated as follows: an extracting liquid is added to the lower aqueous phase for stirring and extraction for 30-50 minutes, wherein the volume ratio of the lower aqueous phase to the extracting liquid is 40-45:1, and the mixture is allowed to stand for 2-4 hours before separation, and the first organic phase on the upper layer and the first wastewater on the lower layer are collected separately, and the first organic phase is combined with the first working liquid and then enters step S2 for treatment.

[0032] Preferably, the first wastewater is added with the extracting liquid again and stirred for extraction for 30-50 minutes, wherein the volume ratio of the lower aqueous phase and the extracting liquid is 40-45:1, and separated after standing for 2-4 hours, and the second organic phase on the upper layer and the second wastewater on the lower layer are collected respectively, the second organic phase is used for extraction of the next batch of the lower aqueous phase, and the second wastewater is subjected to sewage treatment.

[0033] Preferably, the extract is trimethylbenzene or n-eicosane.

[0034] Preferably, the lower aqueous phase is treated as follows: n-eicosane is added to the lower aqueous phase, wherein the volume ratio of the lower aqueous phase to n-eicosane is 45:1, and then stirred and extracted for 30 minutes, and then allowed to stand for 2 hours for two-phase separation, and the first organic phase on the upper layer and the first wastewater on the lower layer are collected respectively; the above operation is repeated to collect the second organic phase on the upper layer and the second wastewater on the lower layer; the first organic phase and the second organic phase are combined and placed in a continuous centrifugal state with a centrifugal speed of 2000rpm, and the temperature is slowly lowered to 20°C at 1°C / h, and the third working solution on the upper layer is collected after being maintained for 20 minutes. The obtained lower solid phase can be reused after melting, and the lower aqueous phase is extracted again.

[0035] Compared with the prior art, the method for recovering working fluid from regenerated wastewater of the present invention has the following beneficial effects:

[0036] 1) The present invention effectively recovers and obtains relatively clean working fluid from regenerated wastewater in an emulsified state composed of a large amount of sewage, alumina powder (or catalyst powder) and degradation products of the working fluid by using methods such as demulsification, separation, multi-stage filtration, cleaning and regeneration, thereby effectively improving the cleanliness, recycling rate and regeneration effect of the working fluid; the use of phosphoric acid, an inorganic acid, will not introduce elements such as chlorine, sulfur and nitrogen into the working fluid to cause pollution, and there is no risk of deactivation of the catalyst.

[0037] 2) Using modified perlite to filter wastewater can aggregate the emulsified oil droplets in the wastewater into large particles, effectively reducing the residual amount of working fluid in the wastewater and further improving the recovery rate of the working fluid; this process does not require the residual liquid to be divided into floccules and wastewater for separate treatment, and the process is simpler.

[0038] 3) Further extraction of residual working fluid in the wastewater by trimethylbenzene or n-eicosane can further reduce the residual working fluid in the wastewater, and the subsequent wastewater treatment pressure is small; there is no need to add chemical components such as flocculants, trimethylbenzene itself is a component of the working fluid and will not pollute the working fluid; and n-eicosane can be completely separated and removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a system for recovering and purifying working fluid in regenerated wastewater according to an embodiment of the present invention;

[0040] Figure 2 It is a partial schematic diagram of the system for recovering and purifying the working fluid in the regenerated wastewater according to an embodiment of the present invention.

[0041] Description of reference numerals:

[0042] 1. Phosphoric acid high-level tank; 2. Delivery pump; 3. Regeneration wastewater separator; 4. Working fluid recovery pump; 5. Primary filter; 6. Secondary filter; 7. Flame arrester; 8. Sight glass; 9. Regeneration wastewater inlet pipe; 10. Sewage discharge pipe; 11. Overflow pipe; 12. Recovery liquid discharge pipe; 13. Regeneration working fluid delivery pipe; 14. Phosphoric acid delivery pipeline; 15. Water addition pipeline; 16-Separation tank; 17-Filter assembly; 18-Mixing device; 181-Proportional pump; 182-Solvent storage tank; 183-Stirring tank; 19-Standing tank. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail in conjunction with the accompanying drawings. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. In the present invention, the distribution ratio of the working liquid in the upper layer and the lower layer after the regenerated wastewater is layered after standing, is about 9:1, wherein the CODCr value of the lower layer of wastewater is 3000-5000 mg / L, and the pH is 5-7. In this application, the stirring speed is set according to the needs, and the liquid is in a stirred state after a certain stirring time.

[0044] In the production of hydrogen peroxide by the anthraquinone method, anthraquinone (2-ethylanthraquinone or tetrahydroanthraquinone, etc.) participates in hydrogenation and oxidation reactions as the main carrier. As a solute, it forms a working solution together with aromatic hydrocarbons, trioctyl phosphate or 2-methylcyclohexyl acetate, tetrabutyl urea and other organic solvents. In the process of hydrogenation and oxidation reaction, anthraquinone is usually accompanied by the generation of hydrogenation degradation products and oxidation degradation products, mainly including anthraquinone, hydroxyanthraquinone, octahydroanthraquinone, decahydroanthraquinone, epoxyanthraquinone, etc. The post-treatment section uses activated alumina to regenerate anthraquinone degradation products and adsorb alkali and water entrained in the working solution. The deactivated alumina is generally steam-purged to remove the working solution components adsorbed on the surface of the alumina particles. Due to the full mixing of steam condensate and residual working solution during the steam purge process, part of the working solution will exist in the form of floating oil (>100μm) and suspended oil droplets (10-100μm), and part of it will be dispersed and suspended in the sewage in the form of emulsified oil (<10μm), resulting in the COD of the sewage often reaching tens of thousands. Since the amount of emulsified oil (about 0.1-10μm) adsorbed on the bubble interface is very small, a large number of bubble interface adsorption droplets are required. It cannot be separated from water by gravity sedimentation technology and flotation technology alone, and conventional process treatment is extremely difficult. At present, it is mainly removed by chemical demulsification, but the chemical demulsification method is highly specific. Different demulsifiers need to be selected for different types of emulsified oil, resulting in high costs; if the demulsifier enters the working fluid, it will cause secondary pollution.

[0045] In addition, since the regenerated wastewater contains a large amount of alumina powder (or catalyst powder), organic degradation products and other impurities, among which alumina powder is easy to pulverize, increases the viscosity of the working fluid and has strong adsorption to aromatic hydrocarbons, some extremely tiny alumina powder forms aluminum hydroxide colloid in water. Aluminum hydroxide colloid has a large specific surface area and strong adsorption capacity. These impurities are often distributed between the water phase and the oil phase to form an intermediate layer. If conventional single-stage precision filtration is used to remove alumina powder (or catalyst powder), it is very easy to clog the filter element. At the same time, if there is escape, it will affect the physical properties of the working fluid; and when the working fluid that is not fully cleaned is mixed with the caustic soda solution for regeneration, it is often severely emulsified, and the working fluid and the alkali solution are difficult to separate, which will also cause the problem of waste of working fluid and difficulty in cleaning. To this end, the applicant proposes the following technical solution:

[0046] Example 1

[0047] A system for recovering and purifying working fluid in regenerated wastewater, such as Figure 1-2 As shown, including:

[0048] A regeneration wastewater tank for storing regeneration wastewater generated in the production of hydrogen peroxide;

[0049] A regeneration wastewater separator 3, wherein the regeneration wastewater separator 3 is connected to a regeneration wastewater tank, a sewage discharge pipe 10 is arranged at the bottom of the regeneration wastewater separator 3, a vent pipe is arranged at the top of the regeneration wastewater separator 3, and a flame arrester 7 is arranged in the vent pipe;

[0050] A phosphoric acid high-level tank 1, which is arranged at the upstream side of the regeneration wastewater separator 3 and is used to add phosphoric acid to the regeneration wastewater entering the regeneration wastewater separator 3;

[0051] A filter assembly, the filter assembly is connected to the regeneration wastewater separator 3;

[0052] The regeneration device is connected to the filtering component, a heating component and a stirring component are arranged on the regeneration device, the top of the regeneration device is respectively connected to the phosphoric acid pipeline, the caustic soda pipeline and the tap water pipeline, and a drainage port is arranged at the bottom of the regeneration device.

[0053] Compared with other inorganic acids, the recovery and purification system of the working fluid in the regenerated wastewater of the present invention adopts phosphoric acid demulsification, which does not involve the risk of introducing chlorine, sulfur and nitrogen elements, which may cause working fluid pollution and catalyst deactivation, and will not change the physical properties of the working fluid, and can effectively ensure the cleanliness of the working fluid; compared with flocculants such as alum, it can make more degradation products in the working fluid enter the water phase to improve the purification effect, and at the same time, it will not introduce aluminum ions into the working fluid to cause hydrogen peroxide decomposition in production; when the regenerated wastewater enters the regenerated wastewater separator 3, the internal air needs to be emptied. Since the working fluid contains organic components such as trimethylbenzene, there are safety hazards when the gas in the regenerated wastewater separator 3 is discharged. By setting a flame arrester 7, fire can be avoided when the regenerated wastewater is fed, thereby ensuring the safety of equipment operation.

[0054] Since the regenerated wastewater contains a large amount of alumina powder or catalyst powder, organic degradation products and other impurities, these impurities are often mixed with the working liquid in an emulsified state and are difficult to separate. During recycling, a large amount of emulsified working liquid is often lost from the water phase. At the same time, when the insufficiently cleaned working liquid is mixed with the caustic soda solution for regeneration, there is serious emulsification, and it is difficult to separate the two, resulting in waste of working liquid and difficulty in cleaning. Phosphoric acid is added before the regenerated wastewater enters the regenerated wastewater separator 3, so that the phosphoric acid demulsifies the emulsified working liquid, thereby promoting the emulsification of the regenerated wastewater in the emulsified state composed of the working liquid, wastewater, alumina powder or catalyst powder, and degradation products in the regenerated wastewater, which can quickly separate the working liquid and sewage two-phase interface, and at the same time, more alumina powder or catalyst powder and working liquid degradation products enter the water phase, reducing the working liquid entrained in the water phase, thereby effectively purifying the recovered liquid, and the residual alumina powder in the recovered working liquid can be further removed by the filtering component, thereby improving the cleanliness and recovery rate of the working liquid.

[0055] The upstream side refers to the side connected to the liquid inlet of the regenerated wastewater separator 3. The regeneration equipment is at least used to perform acid washing, alkaline washing regeneration and acid washing again on the recovered working liquid, so that the anthraquinone degradation products in the working liquid are regenerated and reduced under the action of the alkali to obtain the high-purity working liquid finally recovered. It can be a configuration kettle or a working liquid regeneration cleaning kettle, and its specific structure is the prior art and will not be repeated here. Preferably, there are two regenerated wastewater separators 3 and they are arranged in parallel. This arrangement is conducive to the filtration of regenerated wastewater and other operations.

[0056] Preferably, the regeneration wastewater tank is connected to the regeneration wastewater separator 3 via a regeneration wastewater inlet pipe 9, a delivery pump 2 is provided on the regeneration wastewater inlet pipe 9, and the phosphoric acid high level tank 1 adds phosphoric acid to the upstream side of the delivery pump 2. Preferably, the concentration of the phosphoric acid is 50-60%, preferably 53.5%, and the addition amount is 1m 31L-5L phosphoric acid is added to the regenerated wastewater. If the concentration and dosage of phosphoric acid are too low, the demulsification effect is not ideal, the emulsion decomposition amount is low, and the demulsification speed is low, resulting in a large amount of waste of working fluid; by adding phosphoric acid in the above concentration range to the regenerated wastewater, a better demulsification effect can be obtained, the content of emulsified substances in the regenerated wastewater can be greatly reduced, the recovery of the working fluid can be increased, and the aluminum oxide powder and the degradation products of the working fluid can be promoted to enter the water phase.

[0057] Specifically, the phosphoric acid high-level tank 1 is connected to the regeneration wastewater inlet pipe 9 through a phosphoric acid delivery pipeline 14. The connection point between the phosphoric acid delivery pipeline 14 and the regeneration wastewater inlet pipe 9 is located on the upstream side of the delivery pump 2. The delivery pump 2 is used to deliver the regeneration wastewater in the regeneration wastewater tank to the regeneration wastewater separator 3. This arrangement allows the regeneration wastewater and phosphoric acid to be mixed in the delivery pump 2 and then delivered to the regeneration wastewater separator 3 together, which helps phosphoric acid to fully demulsify the emulsion in the regeneration wastewater, reduce the entrained working fluid in the water phase after standing, and is conducive to improving the recovery rate and cleanliness of the working fluid.

[0058] Preferably, the filter assembly includes a primary filter 5 and a secondary filter 6 arranged in series, the liquid inlet of the primary filter 5 is connected to the regeneration wastewater separator 3 through a recovery liquid discharge pipe 12, the recovery liquid discharge pipe 12 is provided with a working liquid recovery pump 4, the liquid outlet of the secondary filter 6 is connected to the regeneration equipment, and the filtering accuracy of the secondary filter 6 is higher than that of the primary filter 5. This arrangement can perform secondary filtration on the recovered working liquid, with a high filtering speed while having a good impurity removal effect, and on this basis, a regeneration treatment using a regeneration equipment can be performed to obtain a working liquid with high cleanliness and high recovery rate. If single-stage precision filtration is used, the filter element is easily clogged, and single-stage large-pore filtration will cause aluminum oxide powder or escape to affect the physical properties of the working liquid, which is not conducive to the stratification of the alkalization regeneration process.

[0059] Preferably, the filter element precision of the primary filter 5 is 1-10 μm, and the filter element precision of the secondary filter 6 is 0.5-1 μm. This setting can ensure a high removal rate of alumina powder and the like in the recovered working fluid, and effectively avoid large-area emulsification during the subsequent alkalization regeneration process.

[0060] Preferably, a pure water spray pipe is provided on the top of the inner wall of the regenerated wastewater separator 3, and the pure water spray pipe is connected to the pure water source through the water supply pipe 15. In practice, it is found that a part of the working liquid degradation products will float on the upper part of the working liquid, and this part of the organic degradation products does not need to be recovered. As time accumulates, the degradation products floating on the upper layer of the recovered working liquid will accumulate. At this time, it is necessary to spray water through the pure water spray pipe to clean the degradation products remaining on the inner wall and the bottom of the regenerated wastewater separator 3 and discharge them through the sewage discharge pipe 10, thereby ensuring the cleanliness of the regenerated wastewater separator 3 and avoiding affecting the cleanliness of the recovered working liquid.

[0061] Preferably, an interface meter is provided in the regenerated wastewater separator 3, and the interface meter is used to monitor the interface height between the sewage and the recovered working fluid in the regenerated wastewater separator 3. The interface meter is used to assist in controlling the interface position of the two phases, and to discharge the sewage in time according to the interface position, so that the interface of the two phases is close to the bottom of the regenerated wastewater separator 3, so as to prevent the working fluid from being mistakenly discharged into the sewage system or the sewage from being pumped into the working fluid recovery pump 4. In general, there are generally more organic degradation products floating on the upper interface of the recovered working fluid, and there are generally more alumina powder and its combination floating between the lower interface of the recovered working fluid and the upper interface of the sewage. The present application adds phosphoric acid for demulsification, so that the alumina powder and its combination are decomposed and enter more into the water phase, thereby improving the cleanliness of the recovered working fluid.

[0062] Preferably, a level gauge is also provided in the regeneration wastewater separator 3, and the level gauge is used to monitor the upper interface level of the recovered working fluid. This setting can accurately control the amount of wastewater delivered to the regeneration wastewater separator 3 in each batch, so that it is close to the maximum capacity that the regeneration wastewater separator 3 can handle; at the same time, the highest level of the working fluid after static stratification is monitored, thereby preventing the organic degradation products on the uppermost layer of the working fluid from being pumped to the primary filter 5 by the working fluid recovery pump 4, thereby ensuring the cleanliness of the recovered working fluid.

[0063] Preferably, the sewage discharge pipe 10 is provided with a sight glass 8 and a valve, and the valve is arranged on the downstream side of the sight glass 8. The sight glass 8 is used to observe the discharge of sewage to avoid the working fluid from being discharged by mistake. The sewage discharge pipe 10 is used to discharge the sewage separated by static separation in the regeneration wastewater separator 3 to the sewage treatment system. Through the sight glass 8, the cleanliness of the water phase during sewage discharge and the effect of demulsification and separation of the recovered working fluid can be observed. When the working fluid is observed, it indicates that the sewage has been discharged cleanly. At this time, the sewage discharge pipe 10 can be closed by the valve to prevent the recovered working fluid from being discharged by mistake. The valve is arranged on the downstream side of the sight glass 8 to minimize the amount of recovered working fluid discharged from the sewage discharge pipe 10. It should be understood that in order to facilitate the rapid discharge of sewage, the lower part of the regeneration wastewater separator 3 is arranged in a cone shape.

[0064] Optionally, an overflow pipe 11 is provided at the top or near the top of the regeneration wastewater separator 3, and the overflow pipe 11 is connected to the regeneration wastewater tank. This arrangement can avoid the risk of working fluid leakage when the regeneration wastewater is fed excessively or too quickly, and improve the operating safety of the regeneration wastewater separator 3.

[0065] The recovery liquid discharge pipe 12 is connected to the lower part of the regeneration wastewater separator 3. This setting can accumulate as much recovery working liquid as possible through the liquid level control of the two-phase interface and the upper interface of the recovery working liquid, and then perform the next step of filtering and recycling, thereby improving the recovery efficiency and reducing the operation frequency of the filter and the regeneration equipment.

[0066] Example 2

[0067] This embodiment provides a purification system for recovering working fluid from regenerated wastewater. Based on the embodiment 1, further improvements are made. The improvements are as follows:

[0068] like Figure 2 As shown, the system for recovering the working fluid in the regenerated wastewater also includes a filter device 17 and a standing tank 19 which are sequentially arranged on the sewage discharge pipe 10, the filter device 17 is located on the downstream side of the sight glass 8, the top of the standing tank 19 is conical and is connected to the recovery liquid discharge pipe 12, and is used to recover the working fluid in the standing tank 19; the system for recovering the working fluid in the regenerated wastewater also includes a filter aid mixing tank, the liquid inlet and the liquid outlet of the filter aid tank are respectively connected to the water adding pipeline 15, which is used to add the filter aid to the regenerated wastewater separator 3 after adding water.

[0069] As an example of the present invention, the filtering device 17 can be a plate filter or a bag filter. By adding modified perlite to the residual liquid after the static separation of the working liquid, the emulsified droplets in the residual liquid can be promoted to gather into a larger diameter and further separated in the static tank 19. At the same time, the modified perlite can filter out the solid particulate matter originally located in the middle floc layer to facilitate stratification, reduce the pressure and replacement frequency of subsequent post-filtration operations, and even if the perlite leaks, it can be completely filtered out in the subsequent filtration steps to ensure a stable and reliable process.

[0070] Preferably, the system for recovering the working fluid in the regenerated wastewater further comprises a mixing device 18 and a separation tank 16, which are sequentially arranged on the sewage discharge pipe 10, the mixing device 18 is located on the downstream side of the static tank 19, and the top of the separation tank 16 is conical and connected to the recovery liquid discharge pipe 12, and is used to recover the working fluid in the separation tank 16. This arrangement can perform an extraction operation on the filtered wastewater, further reduce the residual working fluid in the wastewater, and improve the recovery rate of the working fluid.

[0071] Preferably, the mixing device 18 includes a proportional pump 181, the inlet end of the proportional pump 181 is connected to the solvent storage tank 182 and the regeneration wastewater separator 3 respectively, the outlet end of the proportional pump 181 is connected to the stirring tank 183, the outlet end of the stirring tank 183 is connected to the separation tank 16, and the volume of the stirring tank 183 is 5%-10% of the regeneration wastewater separator 3. By setting the proportional pump 181, it can be ensured that the organic solvent and the wastewater are accurately mixed in proportion, and cooperate with the stirring tank 183 to realize online continuous extraction and separation. The mixing device 18 occupies a small space and is easy to implement; preferably, the separation tank 16 has two and is arranged in parallel with each other. This setting can be used alternately to cooperate with the mixing device 18 to realize the continuous production of wastewater extraction and static separation. Preferably, there are two mixing devices 18 and they are arranged in series on the sewage discharge pipe 10.

[0072] Preferably, the purification system for recovering the working fluid from the regenerated wastewater further comprises a liquid storage tank and a centrifugal device. The liquid storage tank is located on the downstream side of the mixing device 18 and is used to accommodate the separated organic phase. The inlet and outlet ends of the centrifugal device are respectively connected to the bottom and top of the liquid storage tank. A pump body is arranged between the centrifugal device and the liquid storage tank. The liquid storage tank is provided with a cooling system for cooling the organic phase. This arrangement separates the solvent with a higher melting point from the working fluid to avoid contamination of the working fluid.

[0073] Example 3

[0074] A purification system for recovering working fluid from regenerated wastewater is further improved on the basis of Example 1 or 2, and the improvements are as follows:

[0075] The purification system also includes a demulsification tank (not shown in the drawings), which is arranged on the downstream side of the delivery pump 2 and the phosphoric acid high-level tank 1. An ultrasonic generator is arranged on the upper cover of the demulsification tank, and the ultrasonic generator is used to perform ultrasonic demulsification on the regenerated wastewater in the demulsification tank. Through the above arrangement, the emulsion in the regenerated wastewater is smaller in size and more dispersed in distribution after ultrasonic demulsification. The addition of phosphoric acid can quickly destroy the adsorption performance of the alumina powder therein, thereby improving the demulsification effect of the regenerated wastewater. This embodiment realizes the demulsification effect by combining ultrasound and phosphoric acid. Phosphoric acid is added after ultrasonic treatment. 1m 3 Recycled wastewater can be recycled 0.05-0.1m 3 The working fluid can significantly improve the recovery rate and cleanliness of the working fluid and reduce production costs.

[0076] As one of the optional embodiments, the ultrasonic working frequency is 22-32KHz, and the intensity is 1.0-1.2W / cm. Studies have found that when the ultrasonic working frequency and intensity are within the above range, the emulsion in the anthraquinone regeneration wastewater can be preliminarily demulsified, which helps to improve the effect of subsequent phosphoric acid demulsification, thereby improving the recovery rate and cleanliness of the working fluid. Preferably, the ultrasonic working frequency is 26KHz, and the intensity is 1.1W / cm.

[0077] Example 4

[0078] The present invention also provides a method for recovering and purifying working fluid from regenerated wastewater, comprising:

[0079] Step S1: The regenerated wastewater in the regenerated wastewater tank is transported to the regenerated wastewater separator 3 through the regenerated wastewater inlet pipe 9, and at the same time, the phosphoric acid solution with a mass concentration of 54% in the high-level phosphoric acid tank 1 is transported to the regenerated wastewater separator 3 through the phosphoric acid transport pipeline 14 at a volume ratio of 3:2000, stirred for 20 minutes, and then allowed to stand for separation, and the upper working solution and the first wastewater are collected;

[0080] Step S2: the collected working liquid is sequentially passed through a primary filter 5 containing a 10 μm filter element and a secondary filter 6 containing a 1 μm filter element, and then the filtrate is subjected to a reduction and regeneration treatment, and then subjected to secondary filtration using a 1 μm filter element to obtain a filtrate;

[0081] Preferably, the reduction and regeneration process comprises:

[0082] Step S21: transport the filtrate to the regeneration device and heat it to 50°C, add pure water into the device at a volume ratio of 1:10, then add a phosphoric acid solution with a mass concentration of 54% into the regeneration device at a volume ratio of 3:2000, stir for 10 minutes, let it stand for 2 hours, and discard the pickling wastewater at the bottom layer;

[0083] Step S22: adding a caustic soda solution with a mass concentration of 15% into the regeneration equipment at a volume ratio of 1:100, stirring for 15 minutes and then standing for 3 hours, and discarding the alkali washing regeneration wastewater at the bottom layer;

[0084] Step S23: add pure water into the regeneration equipment at a volume ratio of 1:10, and then add phosphoric acid solution at a volume ratio of 1:200, adjust the final pH to 7.0, stir for 10 minutes and then stand for 4 hours, and collect the upper working solution and the second pickling wastewater.

[0085] Step S3: Dry and remove water from the working liquid collected in step S23.

[0086] After testing the regenerated wastewater treated by the above method, the conductivity of the water phase after the second acid washing was less than 5μS / cm, the recovery rate of the working liquid was 89.6%, the time for the recovered working liquid to be separated from water in the stratification experiment was less than 10s, and the anthraquinone content in the working liquid could be increased by more than 6g / L, with good cleanliness; the lower layer of wastewater after separation in step S1 contained a large amount of emulsified oil, and its COD was 4600ppm. In addition, the intermediate layer between the wastewater and the working liquid was in the form of floccules, of which the working liquid accounted for about 30%, and was usually discharged together with the sewage, resulting in an extremely high COD of the final wastewater.

[0087] By adding phosphoric acid to the regenerated wastewater, the polarity of the water phase can be further increased, which is beneficial to stratification and improves the recovery rate of the working liquid. At the same time, part of the degradation products in the working liquid enter the water phase and are discharged to improve the purification rate of the working liquid. When the working liquid is subjected to reduction and regeneration treatment, the viscosity of the working liquid can be reduced by heating to increase the separation rate from the water phase, but when the temperature further increases and exceeds the flash point of the working liquid, safety hazards will arise. At the same time, a primary acid wash is performed to further demulsify and clean and remove residual hydrogen peroxide and other impurities therein, while an alkali wash operation can regenerate and reduce anthraquinone degradation products, and a secondary alkali wash operation can demulsify the partially emulsified working liquid after alkali treatment and wash away the sodium ions and degradation products dissolved in the working liquid, and at the same time adjust the pH of the working liquid to neutral or slightly acidic (pH: 6-7) to reduce safety hazards to subsequent processes.

[0088] Example 5

[0089] A method for recovering working fluid from regenerated wastewater, comprising:

[0090] Step S1: The regenerated wastewater in the regenerated wastewater tank is transported to the regenerated wastewater separator 3 through the regenerated wastewater inlet pipe 9, and at the same time, the phosphoric acid solution with a mass concentration of 60% in the high-level phosphoric acid tank 1 is transported to the regenerated wastewater separator 3 through the phosphoric acid transport pipeline 14 at a volume ratio of 1:200, stirred for 30 minutes, and then allowed to stand for separation, and the first working liquid in the upper layer is transported to the first filter 5 through the working liquid recovery pump 4; modified perlite is added to the regenerated wastewater separator 3 at a w / v of 0.8% and stirring is started, and the stirring speed is 500 rpm for 20 minutes and then allowed to stand for 1 h later, the second working liquid in the upper layer is transported to the first filter 5 through the working liquid recovery pump 4, the lower aqueous phase is transported to the mixing device 18, and the extractant in the solvent storage tank 182 is accurately transported to the stirring tank 183 through the proportional pump 181 for stirring and extraction for 30 minutes, wherein the extractant is trimethylbenzene, wherein the volume ratio of the lower aqueous phase to trimethylbenzene is 40:1, and the mixture is separated after standing for 2 hours, and the first organic phase in the upper layer and the first wastewater in the lower layer are collected respectively; the above operation is repeated to collect the second organic phase in the upper layer and the second wastewater in the lower layer;

[0091] The modified pearlite is prepared by the following method:

[0092] Step S11: heat 1 L of n-eicosane to 42° C., add 1.9 L of linseed oil and stir for 20 min until the mixture is uniformly mixed;

[0093] Step S12: Add 20 L of naphtha and stir for 15 min until the mixture is uniformly mixed;

[0094] Step S13: Add 7L of perlite and stir evenly, and dry at 140°C for 30 minutes to obtain.

[0095] Step S2: combining the first working solution and the second working solution and performing primary filtration with a 5 μm filter element, then performing reduction and regeneration treatment on the filtrate, and then performing secondary filtration with a 1 μm filter element to obtain a secondary filtrate;

[0096] Preferably, the reduction and regeneration process comprises:

[0097] Step S21: The filtrate is transported to the regeneration equipment through the regeneration working liquid delivery pipe 13 and heated to 65°C, pure water is added to the regeneration equipment at a volume ratio of 3:20, and then a phosphoric acid solution with a mass concentration of 53.5% is added to the regeneration equipment at a volume ratio of 1:200, stirred for 15 minutes and then allowed to stand for 2.5 hours, and the first pickling wastewater at the lower layer is discarded; the 53.5% phosphoric acid solution can come from the high-level phosphoric acid tank 1.

[0098] Step S22: adding a caustic soda solution with a mass concentration of 5% into the regeneration equipment at a volume ratio of 1:10, stirring for 10 minutes and then standing for 3.5 hours, and discarding the alkali washing regeneration wastewater at the lower layer;

[0099] Step S23: Add pure water to the regeneration equipment at a volume ratio of 3:20, and then add a phosphoric acid solution with a mass concentration of 53.5% at a volume ratio of 1:100, adjust the final pH to 6.5, stir for 20 minutes, and then stand for 4.5 hours, and collect the working solution respectively. The first acid wash wastewater, the second acid wash wastewater, and the alkaline wash regeneration wastewater are transported to the second wastewater for combined water treatment.

[0100] Step S3: Dry and remove water from the secondary filtrate of step S2 to obtain.

[0101] After the regenerated wastewater was treated by the above method, the COD of the final wastewater was 584ppm, and the recovery rate of the working solution was 98.4%. After the regenerated wastewater was allowed to stand for stratification, the upper working solution was collected, the residual solution was stirred and then added with modified pearl powder for filtration, and the upper working solution was allowed to stand for separation again. Then, trimethylbenzene was added to the wastewater, which has a high distribution coefficient for emulsified droplets relative to water, and trimethylbenzene is insoluble in water and is one of the components of the working solution. Therefore, the recovery rate of the working solution can be further improved without causing secondary pollution.

[0102] Example 6

[0103] A method for recovering working fluid from regenerated wastewater, comprising:

[0104] Step S1: The regenerated wastewater in the regenerated wastewater tank is transported to the regenerated wastewater separator 3 through the regenerated wastewater inlet pipe 9, and at the same time, the phosphoric acid solution with a mass concentration of 56% in the high-level phosphoric acid tank 1 is transported to the regenerated wastewater separator 3 through the phosphoric acid transport pipeline 14 at a volume ratio of 1:500, stirred for 40 minutes, and then allowed to stand for 2 hours for separation, and the first working liquid in the upper layer is transported to the first filter 5 through the working liquid recovery pump 4;

[0105] Add modified perlite to the regeneration wastewater separator 3 at a w / v ratio of 0.5% and start stirring. Stir at a speed of 1000 rpm for 25 minutes and then stand for 1 hour. Then, the second working liquid in the upper layer is transported to the first filter 5 through the working liquid recovery pump 4, and the lower aqueous phase is transported to the mixing device 18. The extractant in the solvent storage tank 182 is accurately transported to the stirring tank 183 through the proportional pump 181 for stirring and extraction for 30 minutes. The extractant is n-eicosane, wherein the volume ratio of the lower aqueous phase to n-eicosane is 45:1. After standing for 2 hours, separate and collect the first organic phase in the upper layer and the first wastewater in the lower layer respectively; repeat the above operation to collect the second organic phase in the upper layer and the second wastewater in the lower layer;

[0106] After the first organic phase and the second organic phase are combined, they are placed in a continuous centrifugal state with a centrifugal speed of 2000 rpm. At the same time, the temperature is slowly lowered to 20°C at 1°C / h. After maintaining for 20 minutes, the third working solution on the upper layer is collected. The lower solid phase can be reused after melting, and the lower aqueous phase is extracted again.

[0107] The modified pearlite is prepared by the following method:

[0108] Step S11: heat 1 L of n-eicosane to 40° C., add 2 L of linseed oil and stir for 25 min until the mixture is uniformly mixed;

[0109] Step S12: Add 20 L of naphtha and stir for 25 min until the mixture is uniformly mixed;

[0110] Step S13: add 7L of perlite and stir evenly, and dry at 130°C for 50min.

[0111] Step S2: combining the first working solution, the second working solution, and the third working solution and performing primary filtration with a 1 μm filter element, then performing reduction and regeneration treatment on the filtrate, and then performing secondary filtration with a 0.5 μm filter element to obtain a secondary filtrate;

[0112] The reduction and regeneration process comprises:

[0113] Step S21: The filtrate is transported to the regeneration device through the regeneration working liquid delivery pipe 13 and heated to 65° C. Pure water is added to the regeneration device at a volume ratio of 3:20, and then a phosphoric acid solution with a mass concentration of 53.5% is added to the regeneration device at a volume ratio of 1:200. After stirring for 15 minutes, it is allowed to stand for 10 hours, and the first pickling wastewater at the lower layer is discarded;

[0114] Step S22: adding a caustic soda solution with a mass concentration of 5% into the regeneration equipment at a volume ratio of 1:10, stirring for 10 minutes and then standing for 6 hours, and discarding the alkaline washing regeneration wastewater collected at the lower layer;

[0115] Step S23: add pure water to the regeneration equipment at a volume ratio of 3:20, then add a phosphoric acid solution with a mass concentration of 53.5% at a volume ratio of 1:100, adjust the final pH to 6.5, stir for 20 minutes and then stand for 10 hours, collect the working solution and the second pickling wastewater respectively. The first pickling wastewater, the second pickling wastewater, and the alkaline washing regeneration wastewater are transported to the second wastewater for combined treatment.

[0116] Step S3: Dry and remove water from the secondary filtrate of step S2 to obtain.

[0117] After the regenerated wastewater was treated by the above method, the COD of the final wastewater was 375ppm, and the recovery rate of the working fluid was 99.1%. Compared with trimethylbenzene, n-eicosane has a better distribution coefficient for emulsified droplets, which can increase the oil-water interfacial tension in the system and further improve the recovery rate of the working fluid. Since the melting point of n-eicosane is 36-38°C, it can be completely separated from the working fluid by cooling to 20°C and centrifuging at the same time, and will not cause pollution to the existing working fluid.

[0118] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A system for recovering and purifying working fluid in regenerated wastewater, characterized in that: include: A regeneration wastewater tank for storing regeneration wastewater generated in the production of hydrogen peroxide; A regeneration wastewater separator (3), the regeneration wastewater separator (3) being connected to a regeneration wastewater tank, a sewage discharge pipe (10) being arranged at the bottom of the regeneration wastewater separator (3), a vent pipe being arranged at the top of the regeneration wastewater separator (3), and a flame arrester (7) being arranged in the vent pipe; A phosphoric acid high-level tank (1) is arranged on the upstream side of the regeneration wastewater separator (3) and is used to add phosphoric acid to the regeneration wastewater entering the regeneration wastewater separator (3); A filter assembly, the filter assembly being connected to the regenerated wastewater separator (3); A regeneration device, wherein the regeneration device is connected to the filtering component, the regeneration device is provided with a heating component and a stirring component, the top of the regeneration device is respectively connected to a phosphoric acid pipeline, a caustic soda pipeline, and a tap water pipeline, and the bottom of the regeneration device is provided with a drain port; The system for recovering working fluid in regenerated wastewater further comprises a filter device (17) and a standing tank (19) which are sequentially arranged on the sewage discharge pipe (10); the filter device (17) is located on the downstream side of the sight glass (8); the top of the standing tank (19) is conical and communicated with the recovery liquid discharge pipe (12) for recovering the working fluid in the standing tank (19); the system for recovering working fluid in regenerated wastewater further comprises a filter aid mixing tank; the liquid inlet and the liquid outlet of the filter aid mixing tank are respectively communicated with the water adding pipeline (15) for adding the filter aid to the regenerated wastewater separator (3); Use the following method: Step S1: transporting the regeneration wastewater in the regeneration wastewater tank to the regeneration wastewater separator (3), and at the same time transporting the phosphoric acid solution with a mass concentration of 54-60% in the high-level phosphoric acid tank (1) to the regeneration wastewater separator (3) at a volume ratio of 1:200-1:1000, stirring for 20-40 minutes and then standing for separation, collecting the first working liquid and the residual liquid in the upper layer respectively, wherein the source of the regeneration wastewater includes working liquid wash water whose main pollutants are aromatic hydrocarbons, 2-ethylanthraquinone and trioctyl phosphate; or mixed wastewater of water vapor condensate generated during the regeneration of the hydrogenation tower catalyst, which carries a small amount of aromatic hydrocarbons, 2-ethylanthraquinone and trioctyl phosphate; The residual liquid is treated as follows: after the residual liquid is stirred at a speed of 500-1000 rpm for 20-40 minutes, modified perlite is added at a w / v ratio of 0.5-0.8% for filtration, and after standing for 0.5-1 hour, the second working liquid on the upper layer and the lower aqueous phase are collected respectively, and the second working liquid and the first working liquid are then processed in step S2; The modified perlite is prepared by the following method: Step S11: heat n-eicosane to 40-42° C., add linseed oil in a volume ratio of 1.9:1-2.4:1, and stir for 20-25 minutes until the mixture is uniformly mixed; Step S12: Add naphtha in a volume ratio of 1:2-1:4 and stir for 15 minutes until the mixture is uniformly mixed; Step S13: adding perlite and stirring evenly, wherein the volume ratio of perlite to naphtha is 1:2.5-1:3.5 and drying at 140° C. for 30 minutes to obtain; Step S2: After the working fluid in the upper layer passes through the filter assembly, it is transported to the regeneration equipment for regeneration treatment; the regeneration treatment includes: Step S21: transport the filtrate to the regeneration equipment, add pure water into the equipment at a volume ratio of 1:10-3:20, then add a phosphoric acid solution with a mass concentration of 53-60% into the regeneration equipment at a volume ratio of 1:200-3:2000, stir for 10-15 minutes, let stand for 2-4 hours, and discard the pickling wastewater at the bottom layer; Step S22: adding a caustic soda solution with a mass concentration of 5-15% into the regeneration equipment at a volume ratio of 1:10-1:100, stirring for 10-15 minutes and then standing for 3-6 hours, and discarding the alkali washing regeneration wastewater at the bottom layer; Step S23: adding pure water into the regeneration device at a volume ratio of 1:10, and then adding phosphoric acid solution at a volume ratio of 1:200, adjusting the final pH to 7.0, stirring for 10 minutes and then standing for 4 hours, collecting the upper working solution; Step S3: Dry and remove water from the working liquid collected in step S23.

2. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: The regeneration wastewater tank is connected to the regeneration wastewater separator (3) via a regeneration wastewater inlet pipe (9), a regeneration wastewater pump (2) is provided on the regeneration wastewater inlet pipe (9), and the phosphoric acid high-level tank (1) adds phosphoric acid to the upstream side of the regeneration wastewater pump (2).

3. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: The filter assembly comprises a primary filter (5) and a secondary filter (6) which are arranged in series, the liquid inlet of the primary filter (5) being connected to a regenerated wastewater separator (3) via a recovery liquid discharge pipe (12), the liquid outlet of the secondary filter (6) being connected to a regeneration device, the filter element precision of the primary filter (5) being 1-10 μm, and the filter element precision of the secondary filter (6) being 0.5-1 μm.

4. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: A pure water spray pipe is provided on the top of the inner wall of the regenerated wastewater separator (3), and the pure water spray pipe is used to spray pure water into the regenerated wastewater separator (3) for cleaning.

5. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: The regenerated wastewater separator (3) is provided with an interface meter, which is used to monitor the interface height between the sewage and the recovered working fluid in the regenerated wastewater separator (3); the regenerated wastewater separator (3) is also provided with a liquid level meter, which is used to monitor the upper interface liquid level of the recovered working fluid.

6. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: A sight glass (8) and a valve are provided on the sewage discharge pipe (10), wherein the valve is provided on the downstream side of the sight glass (8), and the sight glass (8) is used to observe the discharge of sewage to avoid the erroneous discharge of the working fluid.

7. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: An overflow pipe (11) is provided at the upper part of the regeneration wastewater separator (3) or at a position close to the top, and the overflow pipe (11) is connected to the regeneration wastewater tank.

8. The system for recovering and purifying working fluid in regenerated wastewater according to claim 1, characterized in that: The system for recovering working fluid from regenerated wastewater further comprises a mixing device (18) and a separation tank (16). The mixing device (18) and the separation tank (16) are arranged in sequence on the sewage discharge pipe (10). The mixing device (18) is located on the downstream side of the static tank (19). The top of the separation tank (16) is conical and communicated with the recovery fluid discharge pipe (12) for recovering the working fluid in the separation tank (16).

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