An epichlorohydrin wastewater resourceful treatment system

Abstract

The utility model discloses an epichlorohydrin wastewater resource treatment system, including subcritical water catalytic oxidation unit, catalyst recovery unit and sodium chloride advanced treatment unit of sequential connection, subcritical water catalytic oxidation unit includes epichlorohydrin wastewater storage tank, first booster pump, filter, high pressure pump, heat recovery reactor, heat exchanger, catalytic oxidation reactor, cooler, gas-liquid separator of sequential connection, the catalyst recovery unit includes catalyst recovery separator, the outlet of catalytic oxidation reactor is connected with the inlet of cooler, and the outlet of cooler and gas-liquid separator, catalyst recovery separator are sequentially connected, the sodium chloride advanced treatment unit includes resin remover. The above technical scheme has the advantages of high reaction efficiency, small reactor volume, complete pollutant degradation, no secondary pollution, etc.

Description

Technical Field

[0001] This utility model relates to the field of wastewater recycling and treatment technology, specifically to an epichlorohydrin wastewater resource utilization treatment system. Background Technology

[0002] In the 1960s, the development of the electronics industry led to a rapid increase in the demand for epoxy resins, and epichlorohydrin, one of the two major raw materials for epoxy resins, entered a period of rapid development. Epichlorohydrin (ECH) is an important organic chemical raw material and a crucial intermediate in the petrochemical industry. It is mainly used in the production of epoxy resins, glycerol, chlorohydrin rubber, and other derivatives. It can also be used as a solvent, plasticizer, flame retardant, and surfactant. In China, most domestic production of epichlorohydrin uses the glycerol route, which has lower process costs and is more environmentally friendly, significantly reducing waste compared to the propylene method.

[0003] The reaction equation for the preparation of epichlorohydrin using the glycerol method is as follows. It only requires two reaction steps to obtain the epichlorohydrin product, resulting in a short process flow and low investment costs:

[0004] C3H8O3+2HCl→C3H6OCl2+2H2O;

[0005] C3H6OCl2+NaOH→C3H5ClO+H2O+NaCl.

[0006] Although the glycerol-based epichlorohydrin production process generates relatively little waste, it still produces a large amount of high-concentration sodium chloride wastewater. This wastewater is characterized by high organic matter concentration, high salt content, and is difficult to treat. Discharging it after dilution would result in a significant waste of resources. Existing wastewater treatment equipment generally employs evaporation and crystallization processes, which produce sodium chloride solid waste. Salt resources cannot be reused, and further treatment is difficult. Utility Model Content

[0007] This invention provides an epichlorohydrin wastewater resource recovery system to solve or at least partially solve the above-mentioned technical problems.

[0008] The epichlorohydrin wastewater resource utilization system provided in this embodiment of the utility model includes:

[0009] The subcritical water catalytic oxidation unit, the catalyst recovery unit, and the sodium chloride deep treatment unit are connected in sequence.

[0010] The subcritical water catalytic oxidation unit comprises, in sequence, an epichlorohydrin wastewater storage tank, a first booster pump, a filter, a high-pressure pump, a heat recovery reactor, a heat exchanger, a catalytic oxidation reactor, a cooler, and a gas-liquid separator.

[0011] The catalyst recovery unit includes a catalyst recovery separator. The outlet of the catalytic oxidation reactor is connected to the inlet of the cooler through a heat recovery reactor. The outlet of the cooler is sequentially connected to the gas-liquid separator and the catalyst recovery separator.

[0012] The sodium chloride deep treatment unit includes a resin remover, and the sodium chloride deep treatment unit is connected to the catalyst recovery separator via a third booster pump.

[0013] In some embodiments, the epichlorohydrin wastewater resource recovery system further includes a catalyst dosing tank and a second booster pump, wherein the catalyst dosing tank is connected to the filter via the second booster pump.

[0014] In some embodiments, the epichlorohydrin wastewater resource recovery treatment system further includes an oxygen compressor connected to the heat recovery reactor.

[0015] In some embodiments, a regulating valve is also provided between the cooler and the gas-liquid separator.

[0016] In some embodiments, the gas-liquid separator is also connected to an exhaust gas treatment device.

[0017] In some embodiments, the subcritical water catalytic oxidation unit further includes an online TOC detector located at the outlet of the gas-liquid separator.

[0018] In some embodiments, the subcritical water catalytic oxidation unit further includes a temperature sensor and / or a pressure sensor disposed at the inlet and / or outlet of the catalytic oxidation reactor.

[0019] In some embodiments, a subcritical water catalytic oxidation unit includes a filter, a heat recovery reactor, a heat exchanger, and a catalytic oxidation reactor connected in sequence. The filter mixes and filters the received epichlorohydrin wastewater and catalyst to obtain a filtrate. The heat recovery reactor mixes the filtrate with high-pressure oxygen to obtain a mixed solution. The heat exchanger heats the mixed solution. The catalytic oxidation reactor performs a subcritical catalytic oxidation reaction on the heated mixed solution to obtain an oxidized solution.

[0020] A catalyst recovery unit is connected to the subcritical water catalytic oxidation unit. The catalyst recovery unit receives the oxidizing liquid and alkaline solution, precipitates solid catalyst particles, and recovers the solid catalyst particles by filtration or centrifugation. The recovered catalyst is reacted with concentrated hydrochloric acid at a concentration of 30%-38% and then returned to the system for use; preferably, the concentration of the concentrated hydrochloric acid is 37%.

[0021] A sodium chloride deep treatment unit is connected to the catalyst recovery unit. The sodium chloride deep treatment unit includes a resin remover, which uses salt-resistant resin to remove residual organic matter from the oxidation liquid after the catalyst is separated, to obtain a pure sodium chloride solution.

[0022] The term "pure sodium chloride solution" refers to a solution with a TOC concentration of less than 10 mg / L.

[0023] In some embodiments, the subcritical water catalytic oxidation unit further includes an epichlorohydrin wastewater storage tank and a booster pump connected in sequence, the booster pump being connected to the filter, and the filter and the heat recovery reactor being connected via a high-pressure pump.

[0024] In some embodiments, the epichlorohydrin wastewater resource recovery system further includes a catalyst dosing tank and a booster pump, wherein the catalyst dosing tank is connected to the filter via the booster pump.

[0025] In some embodiments, the epichlorohydrin wastewater resource recovery system is equipped with a special carbon salt-resistant resin for adsorbing small molecule organic matter in the resin remover.

[0026] In some embodiments, the epichlorohydrin wastewater resource recovery treatment system includes a catalyst recovery separator connected to a catalyst dosing tank.

[0027] In some embodiments, the epichlorohydrin wastewater resource recovery system further includes a sodium chloride solution resource recovery device, which is connected to the resin remover. The sodium chloride solution resource recovery device obtains solid sodium chloride, chlorine gas, hydrogen gas, or caustic soda from the sodium chloride solution.

[0028] Compared with the prior art, the present invention has the following advantages: The epichlorohydrin wastewater resource utilization treatment system provided by the present invention has the advantages of high reaction efficiency, small reactor volume, thorough degradation of pollutants, and no secondary pollution; after treatment, the obtained solution has a TOC of less than 10 mg / L, which makes the epichlorohydrin production system more economical and enables better reuse of sodium chloride. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of an epichlorohydrin wastewater resource recovery system provided in an embodiment of this application;

[0030] Attached image annotations:

[0031] 1. Epichlorohydrin wastewater storage tank; 2. First booster pump; 3. Filter; 4. High-pressure pump; 5. Heat recovery reactor; 6. Heat exchanger; 7. Heater; 8. Catalytic oxidation reactor; 9. Cooler; 10. Control valve; 11. Gas-liquid separator; 12. Tail gas treatment equipment; 13. Catalyst recovery separator; 14. Third booster pump; 15. Sodium chloride deep treatment unit; 16. Cleaning storage tank; 17. Cleaning pump; 18. Catalyst dosing tank; 19. Second booster pump; 20. Oxygen compressor. Detailed Implementation

[0032] Many specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] If the terms "first," "second," etc., are used only to distinguish technical features, and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0035] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0036] In the description of this utility model, the reference to terms such as "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application.

[0037] See Figure 1 As shown, an embodiment of this utility model discloses an epichlorohydrin wastewater resource utilization treatment system, comprising:

[0038] The subcritical water catalytic oxidation unit includes an epichlorohydrin wastewater storage tank 1, a first booster pump 2, a filter 3, a high-pressure pump 4, a heat recovery reactor 5, a heat exchanger 6, a catalytic oxidation reactor 8, a cooler 9, and a gas-liquid separator 11, connected in sequence. Concentrated hydrochloric acid is added to the epichlorohydrin wastewater in the storage tank 1, and then the mixture is sent to the filter 3. There, it is mixed with a catalyst supplied to the filter 3 via a catalyst dosing tank 18 and a second booster pump 19. The filtered mixture is then sent to the heat recovery reactor 5 via the high-pressure pump 4, while simultaneously introducing high-pressure oxygen from an oxygen compressor 20. After preheating by the heat exchanger 6, the mixture is sent to the catalytic oxidation reactor 8 for a subcritical catalytic oxidation reaction. Under the action of the catalyst, organic matter is removed, yielding an oxidized liquid.

[0039] Preferably, the filter 3 is a fully automatic differential pressure backwash filter. The fully automatic differential pressure controlled backwash filter is a pressure-type self-cleaning sealed filter with online filtration, decontamination, and discharge functions. It is mainly used for the filtration and purification of circulating water in various closed-loop systems (air conditioning systems, industrial cooling systems, heating systems, etc.). This series of filter mainly operates by backwashing based on the pressure difference between the inlet and outlet water to achieve the function of self-cleaning the filter screen.

[0040] Preferably, the subcritical water catalytic oxidation unit further includes a preheater, which is disposed between the filter 3 and the high-pressure pump 4. The preheater is a preheater of the prior art. Preheating the high-pressure pump 4 before it and setting it to 50°C can reduce the energy consumption for heating the heat recovery reactor 5, further achieving energy saving, environmental protection, and cost reduction effects.

[0041] Preferably, the subcritical water catalytic oxidation unit further includes an online TOC detector, which is located at the outlet of the gas-liquid separator.

[0042] Preferably, the subcritical water catalytic oxidation unit further includes an oxygen concentration meter, which is disposed at the top outlet of the gas-liquid separator. Preferably, the subcritical water catalytic oxidation unit further includes a sensor, which is disposed at the inlet and / or outlet of the catalytic oxidation reactor 8.

[0043] Preferably, the sensor is a pH / ORP sensor. Installing a real-time sensor at the outlet of the catalytic oxidation reactor 8 enables online pH / ORP monitoring, allowing for coordinated adjustment of the pressure reducing valve and oxygen dosage to ensure reaction stability. The principle of ORP measurement is that oxidation-reduction potential (ORP) reflects the redox properties of a solution, typically related to the extent of the redox reaction and the redox state of the substances. An ORP meter uses a redox electrode (usually made of platinum, gold, or other precious metals) to measure the electron concentration or redox potential in a solution. This electrode reacts with redox substances in the solution, generating a potential change related to the redox state of those substances. The ORP value of the solution can be determined by the potential difference between the reference electrode and the redox electrode.

[0044] Preferably, the subcritical water catalytic oxidation unit further includes a temperature sensor and / or a pressure sensor, which are disposed at the inlet and / or outlet of the catalytic oxidation reactor.

[0045] Epichlorohydrin wastewater storage tank 1 is a tank used to store epichlorohydrin wastewater. A vertical tank, made of fiberglass, is preferred.

[0046] The first booster pump 2, the second booster pump 19, and the third booster pump 14, as their names suggest, are pumps used to increase pressure. They draw liquid from the storage tank and pressurize it. This application preferably uses horizontal self-priming pumps for all of them.

[0047] Filter 3 is an indispensable device in pipelines transporting media, used for filtering wastewater, and is typically installed on pressure reducing valves, pressure relief valves, and level control valves. Preferably, the filter consists of a cylindrical body, a stainless steel filter screen, a drain device, a transmission device, and an electrical control device. The stainless steel filter screen, the drain device, the transmission device, and the electrical control device are all housed within the cylindrical body.

[0048] High-pressure pump 4 further pressurizes the filtered mixture. Option 4 is a plunger pump (flow rate 5 m³ / h, pressure 10 MPa), made of Hastelloy alloy resistant to chloride ion corrosion.

[0049] The heat recovery reactor 5 is a device used in this invention to recover the heat generated during the subcritical water catalytic oxidation reaction. Its main function is to transfer the high-temperature heat generated during the reaction to the wastewater entering the system through heat exchange, thereby improving energy utilization efficiency and reducing the overall energy consumption of the system. Preferably, the specific structure of the heat recovery reactor 5 includes (1) Shell: made of high-temperature and corrosion-resistant composite material (such as carbon steel lined with titanium alloy) to ensure stable operation under high temperature and high pressure environment. (2) Heat exchange tube bundle: composed of multiple parallel metal tubes, with wastewater to be preheated flowing inside the tubes and high-temperature oxidizing liquid flowing outside the tubes. (3) Heat medium channel: used to guide the high-temperature oxidizing liquid and the wastewater to be preheated to exchange heat. (4) Insulation layer: insulation material (such as rock wool, glass fiber or polyurethane foam) is set on the outside of the shell to reduce heat loss. (5) Inlet and outlet interfaces: including wastewater inlet, wastewater outlet, oxidizing liquid inlet and oxidizing liquid outlet to ensure smooth fluid flow. The functions of the heat recovery reactor include: energy recovery, reducing the system's demand for external energy by recovering the heat generated during the reaction. To improve reaction efficiency, the preheated wastewater enters the catalytic oxidation reactor 8 at a temperature close to the reaction conditions, reducing the heating load on the reactor and increasing reaction efficiency. To reduce operating costs, heat recovery reduces energy consumption of heating and cooling equipment, lowering operating costs. Heat exchangers can be selected from fixed tube sheet heat exchangers, floating head heat exchangers, or U-tube heat exchangers. Preferably, a U-tube heat exchanger is chosen because it is easier to clean than other heat exchangers, has a higher flow velocity in the tube side, and reduces the risk of scaling.

[0050] The synergistic effects of heat recovery reactor 5 with other components in the system are as follows: (1) Synergistic effect with catalytic oxidation reactor 8: The preheated wastewater enters catalytic oxidation reactor 8, reducing the heating load of the reactor and improving the reaction efficiency. (2) Synergistic effect with cooler 9: The cooled oxidized liquid enters cooler 9 and is further cooled to room temperature, which facilitates subsequent catalyst recovery. (3) Synergistic effect with heat exchanger 6: Heat recovery reactor 5 and heat exchanger 6 together form the heat recovery network of the system, maximizing the utilization of the heat generated during the reaction.

[0051] Heat exchanger 6 is a device used to transfer heat between two or more fluids. In this invention, the main function of heat exchanger 6 is to transfer the heat of the high-temperature oxidizing liquid discharged from catalytic oxidation reactor 8 to the epichlorohydrin wastewater to be treated, thereby preheating the wastewater and reducing the temperature of the oxidizing liquid.

[0052] Preferably, the structure of the heat exchanger includes a shell, heat exchange tube bundle, tube sheet, baffle plate, fluid inlet and outlet, tube side inlet / outlet, shell side inlet / outlet, insulation layer, and support structure. The inlet and outlet interfaces are usually connected by flanges for easy installation and maintenance.

[0053] The synergistic effect of the heat exchanger and the system includes: (1) Synergy with heat recovery reactor 5: The heat exchanger 6 and heat recovery reactor 5 together form the heat recovery network of the system, maximizing the utilization of the heat generated during the reaction. (2) Synergy with catalytic oxidation reactor 8: The preheated wastewater enters catalytic oxidation reactor 8, reducing the heating load of the reactor and improving the reaction efficiency. (3) Synergy with cooler 9: The cooled oxidized liquid enters cooler 9 for further cooling to room temperature, facilitating subsequent catalyst recovery.

[0054] Preferably, the heat exchanger 6 is a shell-and-tube heat exchanger, a plate heat exchanger, or a spiral heat exchanger.

[0055] Through heat recovery via heat exchanger 6, the overall system energy consumption is reduced by 50%-90%, decreasing the energy required for heating wastewater and cooling the oxidizing liquid. Simultaneously, treatment efficiency is improved: when preheated wastewater enters the catalytic oxidation reactor 8, the reaction rate accelerates, and the organic matter removal rate increases. Operating costs are reduced: heat recovery reduces energy consumption and lowers operating costs.

[0056] By efficiently recovering the heat generated during the reaction process, the system's energy utilization efficiency and operational economy are significantly improved. Its rational structural design and clearly defined functions, working synergistically with other components in the system, enable the efficient treatment and resource utilization of epichlorohydrin wastewater.

[0057] The catalytic oxidation reactor 8 is one of the core devices of this invention. It is used to oxidize and decompose organic matter in epichlorohydrin wastewater into small molecule compounds (such as CO2, H2O, etc.) under subcritical water conditions through the action of a catalyst and high-pressure oxygen, thereby achieving efficient wastewater treatment.

[0058] Preferably, the specific structure of the catalytic oxidation reactor 8 includes the following interconnected components: (1) Reactor shell, made of high-temperature, high-pressure, and corrosion-resistant composite material, such as carbon steel lined with titanium alloy. As the main structure of the reactor, it contains the reaction medium and catalyst. The shell is preferably cylindrical, with a design pressure of 5-20 MPa and a design temperature of 200℃-300℃. (2) (3) Oxygen distributor is made of corrosion-resistant metal material, such as titanium alloy. It distributes high-pressure oxygen evenly into the reactor to ensure that oxygen and wastewater are in full contact. Its distributor is usually a porous tube or nozzle structure, arranged at the bottom of the reactor or below the catalyst bed. (4) Fluid distributor is made of corrosion-resistant metal material. It is used to distribute wastewater evenly onto the catalyst bed to ensure that wastewater and catalyst are in full contact. The distributor is usually a porous plate or nozzle structure, arranged at the top of the reactor. (5) Heat exchange tube is made of high-temperature and corrosion-resistant material, such as titanium alloy. It is used to exchange heat inside the reactor to maintain a stable reaction temperature. The coils are arranged around or inside the catalyst bed and heated or cooled by an external heat medium (such as steam or heat transfer oil). (6) Pressure and temperature sensors: Real-time monitoring of pressure and temperature inside the reactor to ensure stable reaction conditions. The sensors are arranged at the inlet and outlet of the reactor, and the data is displayed and recorded in real time by the control system. (7) Safety valve function: Prevents excessive pressure inside the reactor and ensures safe operation of the equipment. The safety valve is located at the top of the reactor and the set pressure is 1.1-1.2 times the operating pressure.

[0059] The specific operating steps of catalytic oxidation reactor 8 are as follows:

[0060] 1. Wastewater and oxygen mixing: Preheated epichlorohydrin wastewater and high-pressure oxygen enter the reactor through a fluid distributor and an oxygen distributor.

[0061] 2. Catalytic oxidation reaction: Under the action of a catalyst, organic matter in wastewater undergoes an oxidation reaction with oxygen to produce small molecule compounds such as CO2 and H2O.

[0062] 3. Heat exchange: The reaction temperature is maintained stable through heat exchange coils to ensure efficient reaction.

[0063] 4. Discharge of reaction products: The oxidized liquid after the reaction is discharged from the bottom of the reactor and enters the heat recovery reactor 5 for heat recovery.

[0064] The functions of the catalytic oxidation reactor include: (1) efficient removal of organic matter: through catalytic oxidation reaction, the recalcitrant organic matter in wastewater is completely decomposed. (2) resource recovery: the heat generated during the reaction can be recovered and utilized through the heat recovery reactor 5. (3) environmental friendliness: the reaction products are CO2 and H2O, with no secondary pollution.

[0065] Catalyst selection and use: At least one of Cu, Ce, Fe, Mo, Co, Ni, and Zn is supported on a catalyst carrier such as activated carbon, alumina, titanium dioxide, or zirconium dioxide. Catalyst dosage: 0.1%-1% of the wastewater mass. Extending catalyst lifespan: Catalysts are recovered and reused through catalyst recovery unit 13, extending their lifespan.

[0066] The operating conditions of the catalytic oxidation reactor include: reaction temperature: 150℃-250℃; reaction pressure: 5-15 MPa; oxygen concentration: high-pressure oxygen supplied by oxygen compressor 20, with the oxygen flow rate adjusted according to the organic matter concentration in the wastewater; pH value: the wastewater pH is adjusted to 1-5 by adding concentrated hydrochloric acid.

[0067] Synergistic effects of the catalytic oxidation reactor and the system: (1) Synergistic effect with heat recovery reactor 5: The high-temperature oxidized liquid after the reaction enters the heat recovery reactor 5 to recover heat for preheating wastewater. (2) Synergistic effect with cooler 9: The cooled oxidized liquid enters the cooler 9 to facilitate subsequent catalyst recovery. (3) Synergistic effect with catalyst recovery unit 13: After cooling and gas-liquid separation, the oxidized liquid after the reaction enters the catalyst recovery unit 13 to recover the catalyst.

[0068] The catalytic oxidation reactor 8 efficiently removes organic matter from wastewater using subcritical water catalytic oxidation technology, while also recovering and utilizing heat and catalyst. Simultaneously, it works synergistically with other components in the system to achieve efficient treatment and resource utilization of epichlorohydrin wastewater. Optionally, the pH of the epichlorohydrin wastewater is adjusted to 1-5 by adding 36%-38% concentrated hydrochloric acid, and a catalyst is added and mixed thoroughly. The catalyst is selected from at least one of Cu, Ce, Fe, Mo, Co, Ni, and Zn, supported on a catalyst carrier such as activated carbon, alumina, titanium dioxide, or zirconium dioxide. The catalyst dosage is 0.1%-1% of the wastewater mass. After being mixed with oxygen and preheated in heat exchanger 6, the wastewater undergoes subcritical water catalytic oxidation in the catalytic oxidation reactor 8, thereby removing most of the organic matter and chromogenic organic matter under the action of the catalyst. The effluent from the subcritical water catalytic oxidation reaction can be heat-recovered in heat recovery reactor 5 for heat recovery, and then further cooled in cooler 9.

[0069] The catalyst recovery unit includes a catalyst recovery separator 13. The outlet of the catalytic oxidation reactor 8 is connected to the inlet of the cooler 9 through a heat recovery reactor 5. The outlet of the cooler is sequentially connected to the gas-liquid separator and the catalyst recovery separator.

[0070] The catalyst recovery separator 13 is used to receive the oxidizing liquid after cooling and gas-liquid separation. In the catalyst recovery separator 13, the pH value of the oxidizing liquid is adjusted by alkaline solution to precipitate solid particles of the catalyst. The solid particles of the catalyst are then recovered by filtration or centrifugation. For example, the pH of the oxidizing liquid obtained after preliminary treatment is adjusted to above 7 using NaOH solution, and then the precipitated catalyst is recovered by filtration or centrifugation. The obtained catalyst is dissolved in 36%-38% concentrated hydrochloric acid and returned to the catalyst dosing tank for reuse.

[0071] The sodium chloride deep treatment unit 15 includes a resin remover, which is connected to the catalyst recovery separator 13 via the third booster pump 14. The resin remover, also known as a resin separator or resin adsorption-desorption device, is used to remove organic matter from the oxidation liquid using salt-resistant resin through adsorption or other methods to obtain a sodium chloride solution. Specifically, after catalyst removal, the oxidation liquid enters a deep treatment process, such as using a special salt-resistant resin to remove remaining organic matter. The resulting high-purity sodium chloride solution is then recycled and reused after a chlor-alkali process or evaporation. The special salt-resistant resin includes resins from the prior art; preferably, it is RapadC carbon ball material prepared by Dalian University of Technology using hydrothermal oxidation technology, specifically a special carbon salt-resistant resin for adsorbing small molecule organic matter.

[0072] Cooler 9. A cooler is a type of heat exchange equipment used to cool fluids. It typically uses water or air as a coolant to remove heat. They can be mainly classified into shell-and-tube coolers, plate coolers, and air-cooled coolers. Coolers are widely used heat exchange devices in industries such as metallurgy, chemical engineering, energy, transportation, light industry, and food processing.

[0073] The gas-liquid separator 11 is a separation device that uses centrifugal separation and wire mesh filtration to remove liquid. It mainly consists of a cylinder, cyclone separator, high-efficiency defoaming screen, and drain valve. It is generally installed before the drying unit to achieve coarse filtration and remove some moisture from the air, thereby reducing the workload of the drying unit.

[0074] Therefore, the epichlorohydrin wastewater resource recovery system provided in this embodiment has the advantages of high reaction efficiency, small reactor volume, thorough degradation of pollutants, and no secondary pollution. This epichlorohydrin wastewater resource recovery system can make the epichlorohydrin production system more economical and better reuse sodium chloride.

[0075] In some embodiments, combined with Figure 1As shown, the subcritical water catalytic oxidation unit includes a filter 3, a heat recovery reactor 5, a heat exchanger 6, and a catalytic oxidation reactor 8 connected in sequence. These are connected by pipelines. For transport, high-pressure pumps or booster pumps are installed on the pipelines as needed. Before the filter 3, there are also epichlorohydrin wastewater storage tanks 1 and 18, which respectively add epichlorohydrin wastewater and catalyst to the filter via a first booster pump 2 and a second booster pump 19, and remove precipitates through the filter.

[0076] In some embodiments, the COD of the epichlorohydrin wastewater prepared by the glycerol method in the epichlorohydrin wastewater storage tank 1 is 8000-35000 mg / L, contains 20-26% sodium chloride, and the main characteristic organic pollutants are crude glycerol, toluene and other polymers, with a pH of 6-11. After gas-liquid mixing, the wastewater is preheated to 200℃-240℃ by heat exchanger 6, and the effluent temperature after reaction in catalytic oxidation reactor 8 can be controlled below 40℃.

[0077] In some embodiments, the liquid after passing through filter 3 enters heat recovery reactor 5 via high-pressure pump 4, while high-pressure oxygen supplied by oxygen compressor 20 also enters heat recovery reactor 5 for thorough mixing. The mixture is preheated by heat exchanger 6 and then enters catalytic oxidation reactor 8 for reaction. The reaction temperature of subcritical water catalytic oxidation is 220℃-290℃, and the reaction pressure is 5-10 MPa. It should be noted that heat exchanger 6 achieves heat exchange via heater 7 using heat transfer oil, and the oxidized liquid after passing through catalytic oxidation reactor 8 can also pass through heat recovery reactor 5 to heat the heat recovery reactor 5, and then enter the next processing unit for further processing.

[0078] In some embodiments, see continue to see Figure 1 The catalyst recovery unit includes a cooler 9, a regulating valve 10, a gas-liquid separator 11, and a catalyst recovery separator 13, which are connected in sequence. Additionally, the gas separated by the gas-liquid separator 11 is treated by a tail gas treatment device 12 before being discharged. Optionally, the tail gas treatment device can be multiple spray-type tail gas absorption devices connected in series.

[0079] It should be noted that, as needed, the regulating valve 10 is also connected to the cleaning tank 16 and the cleaning pump 17 to provide cleaning fluid to the cleaning tank 16. Of course, the cleaning tank 16 mainly provides cleaning fluid for the catalytic oxidation reaction equipment; for example, it is connected to the filter 3 via the cleaning pump 17, thereby cleaning the aforementioned reaction equipment when necessary.

[0080] Heater 7, a heating device, preferably a natural gas thermal oil heater.

[0081] The exhaust gas treatment equipment 12 includes a circulating pump, an absorption tower, and an exhaust gas fan.

[0082] Oxygen compressor 20 is a compressor specifically designed to compress oxygen, increasing its pressure to the required level. Preferably, the piping of the oxygen compressor 20 is made of explosion-proof copper alloy material for safety protection.

[0083] In some embodiments, the sodium chloride deep treatment unit 15 includes a resin remover. Optionally, the resin remover is provided with carbon ball resin for removing other remaining organic matter from the oxidation solution. Preferably, the resin remover is provided with a special carbon salt-resistant resin for adsorbing small molecule organic matter.

[0084] A resin stripper, also known as a resin separator, is a device that uses the affinity / repulsion between a stationary phase and a mobile phase to separate a solute from a solution. Its basic principle is to pass a solution containing the solute through a column packed with resin. The resin adsorbs the target substance in the solution, while other substances flow out through the column. By changing the conditions in the mobile phase, the solute adsorbed on the resin can be eluted, thus achieving separation.

[0085] In some embodiments, the epichlorohydrin wastewater resource recovery system further includes a sodium chloride solution resource recovery device, which is connected to the resin remover. The sodium chloride solution resource recovery device can obtain sodium chloride solid from the sodium chloride solution by evaporation, or obtain chlorine, hydrogen or caustic soda through a chlor-alkali process.

[0086] The sodium chloride solution resource recovery treatment equipment includes existing sodium chloride wastewater treatment equipment.

[0087] In some embodiments, see continue to see Figure 1 As shown, the epichlorohydrin wastewater resource recovery treatment system also includes a catalyst dosing tank 18 and a second booster pump 19. It should be noted that the catalyst recovery separator 13 is also connected to the catalyst dosing tank 18, and is used to receive the catalyst separated by the catalyst recovery separator 13 for reuse. Optionally, the catalyst recovery separator 13 first obtains solid catalyst particles, which are then dissolved in 36%-38% concentrated hydrochloric acid and returned to the catalyst dosing tank. Preferably, the solid particles are dissolved in 37% concentrated hydrochloric acid and returned to the catalyst dosing tank.

[0088] In some embodiments, the epichlorohydrin wastewater resource recovery treatment system further includes an oxygen compressor 20, which is connected to the heat recovery reactor 5 and is used to introduce high-pressure oxygen into the heat recovery reactor 5.

[0089] The recovered catalyst can be reused and returned to the catalyst dosing tank 18.

[0090] The beneficial effects that can be achieved by using the epichlorohydrin wastewater resource recovery system provided in this application include:

[0091] 1. Treating 1 ton of wastewater consumes approximately 80 kWh of energy (mainly from the high-pressure pump and oxygen compressor), with catalyst loss costing approximately 15 yuan / ton. The overall treatment cost is 63 yuan / ton (calculated based on an electricity price of 0.6), which is lower than that of incineration (300+ yuan / ton).

[0092] 2. It can realize the recovery of multiple resources such as heat and catalysts.

[0093] 3. 0.2-0.25 tons of industrial-grade NaCl (purity ≥99.5%) can be recovered from each ton of wastewater, which can offset the treatment cost based on a market price of 500 yuan / ton.

[0094] 4. Environmental compliance: The system proposed in this application generates 1% cleaning and regeneration wastewater per ton of wastewater treated. After biochemical treatment, the wastewater meets environmental requirements, namely, COD ≤ 50 mg / L and Cl⁻ ≤ 100 mg / L, which meets the Class I standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996).

[0095] The epichlorohydrin wastewater storage tank 1, first booster pump 2, filter 3, high-pressure pump 4, heat recovery reactor 5, heat exchanger 6, heater 7, catalytic oxidation reactor 8, cooler 9, regulating valve 10, gas-liquid separator 11, tail gas treatment equipment 12, catalyst recovery separator 13, third booster pump 14, sodium chloride deep treatment unit 15, cleaning storage tank 16, cleaning pump 17, catalyst dosing tank 18, second booster pump 19, and oxygen compressor 20 mentioned in this application can be selected from existing technologies. As a preferred embodiment, the equipment list in this utility model is as follows:

[0096] Serial Number Equipment Name Model Description Material quantity model factory 1 Epichlorohydrin wastewater storage tank Vertical storage tank; V=150m³; φ5600×6200mm Fiberglass 2 units V-150m³ Jizhou Zhongyi Composite Materials Co., Ltd. 2 Booster pump Horizontal self-priming pump; Q=50m³ / h; H=25m Fluorine Lining 2 units IFK 80-65-160 Hangzhou Alkali Pump Co., Ltd. 3 Filter Q=50m³ / h Fluorine Lining 2 units FLS-50m³ / h Hangzhou Xinkai Water Treatment Equipment Co., Ltd. 4 High pressure pump Q = 25 m³ / h, H = 900 m Hastelloy 2 units 3ZH92 Wuxi Changxin High Pressure Pump Manufacturing Co., Ltd. 5 Heat recovery Heat exchanger assembly: S=600㎡ Titanium alloy 1 set E-600㎡ Nanjing Baose Co., Ltd. 6 heat exchanger Heat exchanger: S=1000㎡ Titanium alloy 1 set E-1000㎡ Nanjing Baose Co., Ltd. 7 heater Natural gas thermal oil heater; calorific value: 1.2 million kcal; circulation rate: 250 m³ / h - 1 set TGO-1200kcal Hebei Yineng Boiler Co., Ltd. 8 Catalytic oxidation reactor V=40m³ Titanium alloy composite materials Group 1 T-40m³ Nanjing Baose Co., Ltd. 9 cooler Heat exchanger; S=150㎡ Titanium alloy 1 unit E-150㎡ Nanjing Baose Co., Ltd. 10 regulating valve DN80 Titanium alloy 2 units KV-80 Viduli Valve Co., Ltd. 11 gas-liquid separator V=20m³; Material: TA9 / Q345R Fiberglass 1 unit V-20m³ Jizhou Zhongyi Composite Materials Co., Ltd. 12 exhaust gas treatment equipment Circulating pumps: 3 units, absorption towers: 3 units, exhaust gas fan: 1 unit combination 1 set X-1500 Jizhou Zhongyi Composite Materials Co., Ltd. / Hangzhou Alkali Pump Co., Ltd. 13 Catalyst recovery unit Vertical storage tank; V=0.75m³ PO 1 unit V-0.75m³ Jinwotai Environmental Protection Technology Co., Ltd. 14 Booster pump Horizontal centrifugal pump; Q=25m³ / h, H=32m Fluorine Lining 2 units IFK 65-40-200 Hangzhou Alkali Pump Co., Ltd. 15 Sodium chloride deep treatment unit V=10m³ Steel-lined PO 1 set V-10m³ Jinwotai Environmental Protection Technology Co., Ltd. 16 Cleaning storage tanks V=50m³ 316L 1 unit CV-50m³ Hubei Woril Heavy Industry Co., Ltd. 17 cleaning pump Q = 25 m³ / h, H = 80 m 316L 2 units CDL-32-40 Hangzhou Alkali Pump Co., Ltd. 18 Catalyst dosing tank V=1m³ Fluorine Lining 1 unit V-1m³ Hubei Woril Heavy Industry Co., Ltd. 19 Booster pump Horizontal centrifugal pump; Q=25m³ / h, H=32m Fluorine Lining 2 units IFK 80-65-160 Hangzhou Alkali Pump Co., Ltd. 20 Oxygen compressor Discharge volume: 240 Nm³ / min; Discharge pressure: 9.8 MPa; Power: 90 kW - 1 unit ZW-5 / 80 Hangzhou Oxygen Plant Group Co., Ltd.

[0097] The following examples will provide further explanation:

[0098]

Example 1

[0099] A chemical plant generates 500m³ of epichlorohydrin wastewater. 3The wastewater has a COD of 18,000 mg / L, contains 23% sodium chloride, and has a pH of 8. Characteristic organic pollutants include crude glycerol and other polymers. In the equalization tank, 37% concentrated hydrochloric acid is added to adjust the pH of the epichlorohydrin wastewater to 3. CuCl2 is added as a catalyst and mixed thoroughly. The catalyst dosage is 0.6% of the wastewater mass. It is then mixed with high-pressure oxygen through pipelines and introduced into a heat exchanger, preheated to 240℃, and then fed into a subcritical water catalytic oxidation reactor. The reaction temperature is controlled at 280℃, the reaction pressure at 8 MPa, and the final effluent temperature is controlled at 50℃.

[0100]

Example 2

[0101] A chemical plant generates 150m³ of epichlorohydrin wastewater. 3 The wastewater has a COD of 18,000 mg / L, contains 23% sodium chloride, and has a pH of 8. Characteristic organic pollutants include crude glycerol, toluene, and other polymers. In the equalization tank, 37% concentrated hydrochloric acid is added to adjust the pH of the epichlorohydrin wastewater to 2. FeCl3 is added as a catalyst and mixed thoroughly. The catalyst dosage is 0.6% of the wastewater mass. It is then mixed with high-pressure oxygen through pipelines and introduced into a heat exchanger, preheated to 220℃, and then fed into a subcritical water catalytic oxidation reactor. The reaction temperature is controlled at 270℃, the reaction pressure at 6 MPa, and the final effluent temperature is controlled at 40℃.

[0102]

Example 3

[0103] A chemical plant generates 150m³ of epichlorohydrin wastewater. 3 The wastewater has a COD of 18,000 mg / L, contains 23% sodium chloride, and has a pH of 8. Characteristic organic pollutants include crude glycerol, toluene, and other polymers. In the equalization tank, 37% concentrated hydrochloric acid is added to adjust the pH of the epichlorohydrin wastewater to 3. CeCl3 is added as a catalyst and mixed thoroughly. The catalyst dosage is 0.5% of the wastewater mass. It is then mixed with high-pressure oxygen through pipelines and introduced into a heat exchanger, preheated to 220℃, and then fed into a subcritical water catalytic oxidation reactor. The reaction temperature is controlled at 260℃, the reaction pressure at 7 MPa, and the final effluent temperature is controlled at 40℃.

[0104]

Example 4

[0105] A chemical plant generates 150m³ of epichlorohydrin wastewater. 3The wastewater has a COD of 18,000 mg / L, contains 23% sodium chloride, and has a pH of 8. Characteristic organic pollutants include crude glycerol, toluene, and other polymers. In the equalization tank, 37% concentrated hydrochloric acid is added to adjust the pH of the epichlorohydrin wastewater to 4. CoCl2 is added as a catalyst and mixed thoroughly. The catalyst dosage is 0.6% of the wastewater mass. It is then mixed with high-pressure oxygen through pipelines and introduced into a heat exchanger, preheated to 220℃, and then fed into a subcritical water catalytic oxidation reactor. The reaction temperature is controlled at 265℃, the reaction pressure at 7MPa, and the final effluent temperature is controlled at 40℃.

[0106] Example 5

[0107] For the subcritical water catalytic oxidation of effluent in Example 1, the pH of the resulting oxidation solution was adjusted to 9 using NaOH solution, and the catalyst was recovered by centrifugation. The obtained catalyst could be reused after being dissolved in 37% concentrated hydrochloric acid.

[0108] The oxidized liquid after catalyst removal enters the advanced treatment system, where a special carbon salt-resistant resin is used to remove the remaining organic matter, and the effluent is a high-purity sodium chloride solution.

[0109]

Example 6

[0110] For the subcritical water catalytic oxidation of effluent in Example 2, the pH of the resulting oxidation solution was adjusted to 9 using NaOH solution, and the catalyst was recovered by centrifugation. The obtained catalyst could be reused after being dissolved in 37% concentrated hydrochloric acid.

[0111] The oxidized liquid after catalyst removal enters the advanced treatment system, where a special carbon salt-resistant resin is used to remove the remaining organic matter, and the effluent is a high-purity sodium chloride solution.

[0112]

Example 7

[0113] For the subcritical water catalytic oxidation of effluent in Example 3, the pH of the resulting oxidation solution was adjusted to 9 using NaOH solution, and the catalyst was recovered by centrifugation. The obtained catalyst could be reused after being dissolved in 37% concentrated hydrochloric acid.

[0114] The oxidized liquid after catalyst removal enters the advanced treatment system, where a special carbon salt-resistant resin is used to remove the remaining organic matter, and the effluent is a high-purity sodium chloride solution.

[0115]

Example 8

[0116] For the subcritical water catalytic oxidation of effluent in Example 4, the pH of the resulting oxidation solution was adjusted to 9 using NaOH solution, and the catalyst was recovered by centrifugation. The obtained catalyst could be reused after being dissolved in 37% concentrated hydrochloric acid.

[0117] The oxidized liquid after catalyst removal enters the advanced treatment system, where a special weakly polar, salt-resistant resin is used to remove the remaining organic matter, and the effluent is a high-purity sodium chloride solution.

[0118] The working process of the epichlorohydrin wastewater resource utilization treatment system in this application embodiment includes: adding 36%-38% concentrated hydrochloric acid to the epichlorohydrin wastewater storage tank to adjust the pH of the epichlorohydrin wastewater to 1 to 5, then conveying it to a filter, adding a catalyst to the filter and mixing it evenly, mixing it with high-pressure oxygen conveyed by an oxygen compressor in a heat recovery reactor, and then entering a heat exchanger for preheating before going to a catalytic oxidation reactor for subcritical water catalytic oxidation reaction, removing most of the organic matter and colorimetric organic matter under the action of the catalyst; the effluent from the catalytic oxidation reactor is then treated by the heat recovery reactor... The reactor recovers heat and then enters a cooler for cooling. The cooled liquid then passes through a gas-liquid separator and is adjusted to pH 9 with NaOH solution in a catalyst recovery separator. The catalyst is then recovered by filtration or centrifugation. The obtained catalyst is dissolved in 36%-38% concentrated hydrochloric acid and returned to the catalyst dosing tank for reuse. After catalyst removal, the solution enters a deep treatment system where special salt-resistant resin is used to remove residual organic matter. The high-purity sodium chloride solution after deep treatment is then sent to a sodium chloride solution resource recovery treatment device for chlor-alkali processing or evaporation.

[0119] In summary, the processing path formed according to the embodiments of this application has advantages such as high reaction efficiency, small reactor volume, thorough degradation of pollutants, and no secondary pollution. The embodiments of this application can make the entire epichlorohydrin production system more economical, while also making better use of sodium chloride.

Claims

1. A system for the resource-based treatment of epichlorohydrin wastewater, characterized in that, include: The subcritical water catalytic oxidation unit, the catalyst recovery unit, and the sodium chloride deep treatment unit are connected in sequence. The subcritical water catalytic oxidation unit includes an epichlorohydrin wastewater storage tank, a first booster pump, a filter, a high-pressure pump, a heat recovery reactor, a heat exchanger, a catalytic oxidation reactor, a cooler, and a gas-liquid separator connected in sequence. The catalyst recovery unit includes a catalyst recovery separator. The outlet of the catalytic oxidation reactor is connected to the inlet of the cooler through the heat recovery reactor. The outlet of the cooler is sequentially connected to the gas-liquid separator and the catalyst recovery separator. The sodium chloride deep treatment unit includes a resin remover, and the sodium chloride deep treatment unit is connected to the catalyst recovery separator via a third booster pump; The epichlorohydrin wastewater resource utilization system also includes a catalyst dosing tank and a second booster pump, wherein the catalyst dosing tank is connected to the filter via the second booster pump; The epichlorohydrin wastewater resource recovery system also includes an oxygen compressor, which is connected to the heat recovery reactor. A regulating valve is also provided between the cooler and the gas-liquid separator; The gas-liquid separator is connected to the exhaust gas treatment equipment.

2. The epichlorohydrin wastewater resource recovery system according to claim 1, characterized in that, The subcritical water catalytic oxidation unit further includes an online TOC detector, which is located at the outlet of the gas-liquid separator.

3. The epichlorohydrin wastewater resource recovery system according to claim 1, characterized in that, The subcritical water catalytic oxidation unit further includes a temperature sensor and / or a pressure sensor, which are disposed at the inlet and / or outlet of the catalytic oxidation reactor.

4. The epichlorohydrin wastewater resource recovery system according to claim 1, characterized in that, In the subcritical water catalytic oxidation unit, the filter mixes and filters the received epichlorohydrin wastewater and catalyst to obtain filtrate, the heat recovery reactor mixes the filtrate and high-pressure oxygen to obtain a mixed solution, the heat exchanger heats the mixed solution, and the catalytic oxidation reactor performs a subcritical catalytic oxidation reaction on the heated mixed solution to obtain an oxidized solution; The catalyst recovery unit receives the oxidizing liquid and alkaline solution, precipitates catalyst solid particles, and recovers the catalyst solid particles by filtration or centrifugation. The recovered catalyst is reacted with concentrated hydrochloric acid at a concentration of 30%-38% and then returned to the epichlorohydrin wastewater resource treatment system for use. The resin remover uses salt-resistant resin to remove residual organic matter from the oxidation liquid after the catalyst has been separated, obtaining a pure sodium chloride solution.

5. The epichlorohydrin wastewater resource recovery system according to claim 1, characterized in that, The resin remover is equipped with a special carbon salt-resistant resin for adsorbing small molecule organic matter.

6. The epichlorohydrin wastewater resource recovery system according to any one of claims 1-5, characterized in that, The catalyst recovery separator is connected to the catalyst dosing tank.

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