A clean production device for alkylene oxide chlorohydrins based on closed-loop recycling of chlorine

Abstract

A clean production device for alkylene oxide chlorohydrins based on closed-loop recycling of chlorine comprises a chlorine dissolver and a propylene distributor connected to a chlorohydrinization reactor, which is then connected to a flash tower. The tail gas outlet at the top of the flash tower is connected to an alkali scrubber and then to a propylene recovery system, forming a chlorohydrinization subsystem; a pipeline causticizing reactor and a stripping tower, forming a causticizing subsystem; a fore-distillation tower and a distillation tower connected in series, forming a propylene oxide distillation subsystem; an electromagnetic heating pipeline gasification reactor and a supercritical delayed gasification reactor forming a causticizing wastewater treatment subsystem; chlorine from an electrolytic cell of a NaCl solution electrolysis subsystem enters the chlorine dissolver of the chlorohydrinization subsystem, and NaOH electrolyte enters the pipeline causticizing reactor of the causticizing subsystem; the chlorohydrinization subsystem is connected to the pipeline causticizing reactor of the causticizing subsystem; crude alkylene oxide at the top of the stripping tower of the causticizing subsystem enters the fore-distillation tower of the alkylene oxide distillation subsystem, and causticizing wastewater at the bottom of the stripping tower enters the electromagnetic heating pipeline gasification reactor of the causticizing wastewater treatment subsystem.

Description

1. Technical Field

[0001] The invention provides an alkylene oxide chlorohydrin method clean production device based on closed-loop recycling of chlorine, and relates to the field of fine chemicals. 2. Background Technology

[0002] The chlorohydrin process for producing alkylene oxide involves preparing hypochlorous acid with chlorine and water. C2-C7 olefins react with the hypochlorous acid to produce chlorohydrins, which are then reacted with slaked lime or caustic soda to produce alkylene oxide. These chlorohydrins are then separated by conventional distillation to yield refined alkylene oxide. The chlorohydrin process for producing propylene oxide was industrialized as early as 1931. It features a mature production process, a short process flow, high operating load flexibility, good selectivity, low raw material purity requirements, safe and stable production, low construction investment, and highly cost-competitive products. Currently, approximately 40% of global propylene oxide production capacity is produced by the chlorohydrin process. However, conventional chlorohydrin process equipment is environmentally unfriendly, with high water and chlorine consumption. The resulting chloride-containing caustic wastewater is difficult to treat, polluting the environment. Furthermore, the chloric acid produced is highly corrosive to equipment. For example, for every ton of propylene oxide produced, approximately 1.5 tons of chlorine are consumed, and at least 40 tons of caustic wastewater containing small amounts of organic chlorides and over 2 tons of CaCl2 waste residue are generated.

[0003] To address the three wastes and corrosion associated with the chlorohydrin process for producing propylene oxide, co-oxidation and direct oxidation have been developed both domestically and internationally. The co-oxidation process overcomes the drawbacks of the chlorohydrin process, such as high corrosiveness and high wastewater production. However, its drawbacks include a lengthy process flow, a wide variety of raw materials, high propylene purity requirements, and expensive equipment. Propylene oxide produces significant amounts of co-products in the co-oxidation process, with 2.5 tons of styrene or 2.4 tons of tert-butyl alcohol produced for every ton of propylene oxide. The advantages of this process are only realized when market demand for propylene oxide and co-products matches. Furthermore, this process produces wastewater with a high COD content, with treatment costs accounting for approximately 10% of the total investment. The advantages of the direct oxidation process lie in its high conversion rate and selectivity, with wastewater production at only 30% of that of existing alternative technologies and energy consumption at 65%. The process is simple and economical, with water as a byproduct, resulting in minimal environmental pollution, land use, and minimal plant infrastructure investment, potentially reducing investment by 25%. However, the technology is immature, costs high, and safety is poor.

[0004] To this end, Dow Chemical Company in the United States replaced the lime milk (primarily composed of Ca(OH)2) used in the causticizing reaction with a 10% to 20% NaOH electrolyte. This significantly reduced the concentrations of propylene glycol (PDO) and dichloropropane (DCP) in the saponification wastewater, resulting in a relatively pure brine solution (primarily composed of NaCl and H2O). The causticizing brine solution is refined to produce saturated brine, which is then fed to an electrolytic cell, where electrolysis produces chlorine, hydrogen, and sodium hydroxide. The chlorine serves as the raw material for the chlorohydrin process, while the sodium hydroxide is recycled to participate in the saponification reaction, improving the economic efficiency of the reaction. While this improvement effectively reduces the amount of wastewater and waste residue (primarily composed of CaCl2) produced after saponification, reducing pollution to soil and water sources, the current difficulty and cost of refining the causticizing brine make it difficult to meet the requirements of chlor-alkali electrolytic cells.

[0005] If the existing chlorohydrin process for producing alkylene oxides using NaOH causticization could cost-effectively address the challenges of treating chloride-containing caustic wastewater and recycling brine, achieving closed-loop chlorine recycling and significantly reducing both propylene oxide costs and water consumption, then the chlorohydrin process would offer significant development advantages over co-oxidation and direct oxidation. However, existing caustic wastewater treatment processes have failed to fully utilize this wastewater as a resource. There is an urgent need to develop efficient, clean, and energy-efficient processes and equipment for the chlorohydrin process to eliminate the industrial bottlenecks of high pollution and high water consumption associated with the chlorohydrin process and enhance its market competitiveness. 3. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing chlorohydrin-based alkylene oxide technology and to invent a clean production device for alkylene oxide by chlorohydrin-based alkylene oxide based on closed-loop chlorine recycling. The device comprises: a NaOH electrolyte rapidly causticizes chlorohydrin in a pipeline reactor; the causticized waste liquid is supercritically gasified in an electromagnetic heating pipeline reactor and a supercritical delayed gasification reactor, and the gas-liquid mixed phase is separated from the NaCl phase; salt is discharged in a high-pressure lock hopper; and waste heat of high-temperature purified water is recovered and recycled. The NaCl solution diluted with part of the purified water in the high-pressure lock hopper is used to produce chlorine and recycle the NaOH electrolyte. The device solves the industrial bottleneck of high water consumption, high pollution, and difficulty in fully resource-recovering the causticized waste liquid in the production of propylene oxide by chlorohydrin-based alkylene oxide at a low cost, and eliminates the severe corrosion of equipment caused by chloric acid generated by the disposal of the causticized waste liquid, thereby realizing clean production of propylene oxide by chlorohydrin-based alkylene oxide with low water consumption, low energy consumption, and closed-loop chlorine recycling.

[0007] The technical solution of the present invention:

[0008] A clean production device for alkylene oxide chlorohydrins based on closed-loop recycling of chlorine, wherein the circulating purified water inlet is connected to the chlorohydrin reactor through a chlorine dissolver and a propylene distributor in sequence, the chlorohydrin reactor is then connected to a flash tower, and the tail gas outlet at the top of the flash tower is connected to an alkali scrubber and then to a propylene recovery system, forming a chlorohydrin subsystem, wherein the circulating purified water temperature is 35-45°C, the molar ratio of chlorine to propylene is 1:1.01-1.1, the reaction pressure is normal pressure or slightly higher than normal pressure, and the reaction temperature is 50-70°C, generating a solution containing 3.0wt%-6.0wt% of chloropropanol, wherein the solution contains hydrochloric acid equimolar to the chloropropanol; the NaOH electrolyte inlet is connected through a pipeline A causticizing reactor is connected to a stripping tower to form a causticizing subsystem. The concentration of the NaOH electrolyte is 10wt% to 20wt%, the molar ratio of sodium hydroxide to chloropropanol + hydrochloric acid is 1.0 to 1.2:1, the causticizing reaction temperature is controlled at 90 to 95°C, the reaction time is controlled at 0.5 to 2 seconds, the concentration of crude propylene oxide at the top of the stripping tower is 90wt% to 95wt%, the absolute pressure at the top of the stripping tower is 25 to 65KPa, and the NaCl concentration in the causticized wastewater at the bottom of the stripping tower is 2.5wt% to 5.5wt%. A fore-distillation tower and a distillation tower are connected in series to form a propylene oxide distillation subsystem. The crude propylene oxide material first passes through the fore-distillation tower, and the finished propylene oxide is discharged from the fore-distillation tower. The high-boiling-point components are discharged from the top of the distillation tower. The operating pressure of the fore-distillation tower and the distillation tower is atmospheric pressure, the bottom temperature is controlled at 50°C to 85°C, and the causticized wastewater is discharged from the bottom of the distillation tower; the high-pressure pump is connected to the supercritical delayed gasification reactor through an electromagnetic heating pipeline gasification reactor, and the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor is connected to the high-temperature purified water outlet of the gas-liquid separation tank respectively, forming a causticized wastewater treatment subsystem; the diluted brine inlet is connected to the electrolytic cell of the NaCl solution electrolysis subsystem, the chlorine outlet of the electrolytic cell is connected to the chlorine dissolver of the chlorohydrin subsystem through a compressor, and the NaOH electrolyte is connected to the pipeline causticization reactor of the causticization subsystem through a pressure pump. the chlorohydrinization subsystem is connected to the inlet of the pipeline causticizing reactor of the causticizing subsystem through the chlorohydrin solution outlet at the bottom of the flash tower, the crude alkylene oxide outlet at the top of the stripping tower of the causticizing subsystem is connected to the inlet of the fore-distillation tower of the alkylene oxide rectification subsystem, the causticized wastewater outlet at the bottom of the stripping tower is connected to the inlet of the electromagnetic heating pipeline gasification reactor of the causticizing wastewater treatment subsystem, and the waste liquid outlet of the tail gas scrubber of the chlorohydrinization subsystem and the causticized wastewater outlet at the bottom of the distillation tower of the propylene oxide rectification subsystem are also connected to the inlet of the electromagnetic heating pipeline gasification reactor; the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor of the causticizing wastewater treatment subsystem is connected to the electrolytic cell of the NaCl solution electrolysis subsystem.

[0009] Among them, the chlorine dissolver is a microporous pipeline chlorine dissolver, a jet pump chlorine dissolver or a T-type straight tube chlorine dissolver.

[0010] The propylene distributor is a microporous pipeline mixer or a jet pump mixer, and the chlorohydrinization reactor is a pipeline reactor with an internal mixing element reinforcement, a single-tower chlorohydrin reactor, a single-tower multi-tower chlorohydrin reactor in series, a tube-tower chlorohydrin reactor or a tubular reactor.

[0011] In order to improve the conversion rate of chloropropanol during the causticizing reaction in a pipeline causticizing reactor, the amount of NaOH added should be excessive, and the NaOH content in the causticizing wastewater should be controlled at 0.01% to 1.3wt%.

[0012] The caustic wastewater at the bottom of the stripping tower is pressurized to ≥22.1MPa by a high-pressure pump and then heat-exchanged with the supercritical gasified synthesis gas and supercritical high-temperature purified water. The preheated caustic wastewater is heated to 400-700°C by an electromagnetic heating tubular reactor for supercritical gasification reaction. The supercritical gasified gas and liquid enter the supercritical delayed gasification reactor and stay there for 1-180 minutes to generate a mixture of synthesis gas and supercritical high-temperature purified water and a high-concentration NaCl slurry. The extracted synthesis gas and supercritical high-temperature purified water mixture is heat-exchanged with the high-pressure dissolved oxygen caustic wastewater for gas-liquid separation, the synthesis gas is discharged, and the purified water is reused. The high-concentration NaCl slurry is discharged through the bottom lock of the supercritical delayed gasification reactor. The hopper is switched and diluted with part of the purified water to 31.5%-36.1% concentrated brine and then returned to the electrolytic cell for recycling; the electromagnetic heating tubular reactor is a tubular reactor in which, under the action of the electromagnetic heating controller, high-frequency alternating current generates an alternating magnetic field through the coil, and the tubular reactor wall and the internal self-mixing strengthening internal components generate eddy current self-heating, thereby achieving uniform heating of the high-pressure dissolved oxygen causticizing waste liquid, rapid temperature increase and gasification reaction; the self-mixing strengthening internal components are regular packing type, X-cross plate type or spiral plate type; a funnel-shaped liquid extraction port is provided in the center of the supercritical delayed gasification reactor, the funnel is connected to the upper part of the reactor, a gas-liquid mixed phase discharge port is provided on the top of the reactor, and two or more salt discharge lock hoppers are provided at the bottom of the reactor.

[0013] The electrolyzer is an oxygen anion membrane electrolyzer or an anion membrane electrolyzer.

[0014] The present invention will be described in detail with reference to embodiments. 4. Description of the Figures

[0015] Attachment Figure 1 It is a process schematic diagram of the present invention.

[0016] Attachment Figure 1 The following is a description of the drawings:

[0017] 1. Chlorine dissolver 2. Propylene distributor 3. Chlorohydrin reactor 4. Flash tower 5. Alkali scrubber 6. Pipeline causticizing reactor 7. Stripping tower 8. Supercritical gasification unit 9. Fore-distillation tower 10. Rectification tower 11. Chlor-alkali electrolyzer A. Propylene inlet B. Purified tail gas outlet C. Ethylene oxide product outlet D. Heavy component outlet E. Causticizing liquid outlet F. Syngas outlet

[0018] Attachment Figure 2 The following is a description of the drawings:

[0019] 12. High-pressure pump 13. Heat exchanger 14. Electromagnetic heating tubular reactor 15. Electromagnetic heating controller 16. Supercritical delayed gasification reactor 17. Gas-liquid separation tank G, NaOH caustic waste liquid inlet L, synthesis gas outlet M, purified water outlet N, diluted brine outlet

[0020] The process characteristics of the present invention are described in detail below with reference to the accompanying drawings and embodiments. 5. Specific implementation methods

[0021] In an embodiment, a clean production device for alkylene oxide chlorohydrins based on closed-loop recycling of chlorine is provided. The circulating purified water inlet is connected to the chlorohydrin reactor (3) through a chlorine dissolver (1) and a propylene distributor (2) in sequence. Propylene is connected to the propylene distributor (2) through a propylene inlet A. The chlorohydrin reactor (3) is then connected to a flash tower (4). The tail gas outlet of the flash tower (4) is connected to an alkali washing tower (5) and then to a propylene recovery system through a purified tail gas outlet B, thereby forming a chlorohydrin subsystem. The circulating purified water temperature is 35-45° C., the molar ratio of chlorine to propylene is 1:1.01-1.1, the reaction pressure is normal pressure or slightly higher than normal pressure, the reaction temperature is 50-70° C., and the generated chlorohydrin is 3.0w t% to 6.0wt% solution containing hydrochloric acid in an equimolar amount to that of chloropropanol; a NaOH electrolyte inlet G is connected to a stripping tower (7) through a pipeline causticizing reactor (6) to form a causticizing subsystem, wherein the concentration of the NaOH electrolyte is 10wt% to 20wt%, the molar ratio of sodium hydroxide to chloropropanol + hydrochloric acid is 1.0 to 1.2:1, the causticizing reaction temperature is controlled at 90 to 95°C, the reaction time is controlled at 0.5 to 2 seconds, the concentration of crude propylene oxide at the top of the stripping tower (7) is 90wt% to 95wt%, the absolute pressure at the top of the stripping tower (7) is 25 to 65KPa, and the NaCl concentration in the causticized wastewater at the bottom of the stripping tower (7) is 2.5wt% to 5.5wt%; a front distillation tower (9) and a distillation tower (10) are connected in series to form a propylene oxide distillation subsystem, the crude propylene oxide material first passes through the front distillation tower (9), the finished propylene oxide is extracted from the ethylene oxide product outlet C at the top of the front distillation tower (9), and the high-boiling point component is discharged from the heavy component outlet D at the top of the distillation tower (10), the operating pressure of the front distillation tower (9) and the distillation tower (10) is atmospheric pressure, the bottom temperature is controlled at 50°C to 85°C, and the causticized liquid outlet E at the bottom of the distillation tower (10) discharges causticized wastewater; high pressure The pump (12) is connected to the supercritical delayed gasification reactor (16) through the electromagnetic heating pipeline gasification reactor (13), and the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor (16) is respectively connected to the high-temperature purified water outlet M of the gas-liquid separation tank (17). The top of the gas-liquid separation tank (17) is provided with a synthesis gas outlet F, and the bottom of the salt discharge lock hopper is provided with a diluted brine outlet N, forming a caustic wastewater supercritical gasification device (8) treatment subsystem; the diluted brine inlet is connected to the chlor-alkali electrolysis of the NaCl solution electrolysis subsystem The chlorine gas outlet of the chlor-alkali electrolytic cell (11) is connected to the chlorine dissolving device (1) of the chlorohydrination subsystem through a compressor, and the NaOH electrolyte is connected to the pipeline causticizing reactor (6) of the causticizing subsystem through a high-pressure pump; the chlorohydrin solution outlet at the bottom of the flash tower (4) of the chlorohydrinization subsystem is connected to the inlet of the pipeline causticizing reactor (6) of the causticizing subsystem, the crude alkylene oxide outlet at the top of the stripping tower (7) of the causticizing subsystem is connected to the inlet of the fore-distillation tower (9) of the alkylene oxide distillation subsystem, and the stripping tower (7) is connected to the inlet of the fore-distillation tower (9) of the alkylene oxide distillation subsystem. (7) The bottom caustic wastewater outlet is connected to the inlet of the electromagnetic heating pipeline gasification reactor (14) of the caustic wastewater treatment subsystem. At the same time, the waste liquid outlet of the tail gas alkali scrubber (5) of the chlorohydrin subsystem and the bottom caustic wastewater outlet of the distillation tower (10) of the propylene oxide distillation subsystem are also connected to the inlet of the electromagnetic heating pipeline gasification reactor (14); the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor (16) of the caustic wastewater treatment subsystem is connected to the chlor-alkali electrolysis cell (11) of the NaCl solution electrolysis subsystem.

[0022] Wherein, the chlorine dissolver (1) is a microporous pipeline chlorine dissolver, a jet pump chlorine dissolver or a T-shaped straight tube chlorine dissolver.

[0023] The propylene distributor (2) is a microporous pipeline mixer or a jet pump mixer, and the chlorohydrinization reactor is a pipeline reactor with an internal mixing element reinforcement, a single-tower chlorohydrin reactor, a single-tower multi-tower chlorohydrin reactor in series, a tube-tower chlorohydrin reactor or a tubular reactor.

[0024] The causticizing reaction is carried out in the pipeline causticizing reactor (6). In order to improve the conversion rate of chloropropanol, the amount of NaOH added should be excessive, and the NaOH content in the causticizing wastewater should be controlled at 0.01% to 1.3wt%.

[0025] In the treatment subsystem of the supercritical gasification device (8) for caustic wastewater, the caustic wastewater at the bottom of the stripping tower (7) is pressurized to ≥22.1 MPa through the NaOH caustic wastewater inlet G by a high-pressure pump (12), and then heat-exchanged with the supercritical gasified synthesis gas and the supercritical high-temperature purified water mixed phase through a heat exchanger (13); the preheated caustic wastewater is heated to 400-700°C by an electromagnetic heating tubular reactor (14) for supercritical gasification reaction, and the supercritical gasified gas and liquid enter the supercritical delayed gasification reactor (16) and stay there for 1-180 minutes to generate a mixed phase of synthesis gas and supercritical high-temperature purified water and a high-concentration NaCl slurry; the extracted synthesis gas and supercritical high-temperature purified water mixed phase are heat-exchanged with the high-pressure dissolved oxygen caustic wastewater through the heat exchanger (13) and then enter the gas-liquid separator (17) for gas-liquid separation, and the synthesis gas is discharged from the synthesis gas outlet L( Figure 1 F) discharge, purified water reuse; high-concentration NaCl slurry is switched through the bottom lock hopper of the supercritical delayed gasification reactor (16), and is diluted with part of the purified water to become 31.5%-36.1% concentrated brine and then returned to the chlor-alkali electrolysis cell (11) for recycling; the electromagnetic heating tubular reactor (14) is under the action of the electromagnetic heating controller (15), when high-frequency alternating current passes through the coil to generate an alternating magnetic field, the tubular reactor wall and the internal self-mixing strengthening internal components generate eddy current self-heating, thereby achieving uniform heating of high-pressure dissolved oxygen caustic waste liquid, rapid temperature increase and gasification reaction; the self-mixing strengthening internal components are regular packing type, X cross plate type or spiral plate type; a funnel-shaped liquid extraction port is set at the center of the supercritical delayed gasification reactor (17), the funnel is connected to the upper part of the reactor, a gas-liquid mixed phase discharge port is set at the top of the reactor, and two or more salt discharge lock hoppers are set at the bottom of the reactor.

[0026] The chlor-alkali electrolyzer (11) is an oxygen anion membrane electrolyzer or an anion membrane electrolyzer.

[0027] The specific reaction conditions and experimental results are as follows:

[0028] (1) Under conditions of 24 MPa and 450°C, the supercritical gasification reaction lasts for 2 seconds and the supercritical delayed gasification reaction lasts for 10 minutes. The COD removal rate is 99.1%, and the brine quality meets the requirements of electrolysis in a chlor-alkali electrolyzer. The synthesis gas contains 70% H2 and 10% CO. Using an anion membrane electrolyzer, NaOH electrolyte, H2, and chlorine are generated. The NaOH electrolyte and chlorine are recycled, and H2 is mixed with the synthesis gas for chemical synthesis.

[0029] (2) Under heating conditions of 24 MPa and 550°C, the supercritical gasification reaction lasted 2 seconds, and the supercritical delayed gasification reaction lasted 5 minutes. The COD removal rate was 99.9%, and the brine quality fully met the requirements for electrolysis in a chlor-alkali electrolyzer. The syngas contained 65% H2 and 8% CO. Using an oxygen anion membrane electrolyzer, only NaOH electrolyte and chlorine were produced, reducing electrolysis energy consumption by 35%.

[0030] This method is not only used for the production of propylene oxide by the chlorohydrin process, but can also be used for the resource-based epoxidation of olefins such as ethylene, butene, and pentene.

[0031] The clean production device for alkylene oxide chlorohydrins based on closed-loop recycling of chlorine provided by the present invention uses NaOH causticizing and supercritical gasification treatment of causticizing wastewater to electrolyze and produce NaOH electrolyte and chlorine to ensure recycling. At the same time, a pipeline reactor strengthens heat and mass transfer and inhibits salt precipitation, scaling and corrosion by strengthening internal components through self-mixing. A supercritical delayed gasification reactor improves gasification efficiency while utilizing the characteristics of supercritical water to achieve separation of water-gas miscible phase and salt phase. Organic matter in the causticizing wastewater is completely gasified to produce synthesis gas containing more than 60% H2, with a COD removal rate of more than 99%. The brine concentration can be flexibly adjusted with low cost and low energy consumption according to the needs of the electrolyzer. The cost and investment for resource-based treatment of NaOH causticizing wastewater are reduced by more than 70% compared with traditional treatment methods, eliminating the high water consumption and high pollution of the chlorohydrin process, increasing the yield of propylene oxide by 3 percentage points and the selectivity by 10%, thereby achieving closed-loop utilization of chlorine.

Claims

1. A clean production device for alkylene oxide chlorohydrin process based on closed-loop recycling of chlorine, characterized in that The circulating purified water inlet is connected to the chlorohydrinization reactor through a chlorine dissolver and a propylene distributor in sequence. The chlorohydrinization reactor is then connected to a flash tower. The tail gas outlet at the top of the flash tower is connected to an alkali scrubber and then to a propylene recovery system, forming a chlorohydrinization subsystem. The circulating purified water temperature is 35-45°C, the molar ratio of chlorine to propylene is 1:1.01-1.1, the reaction pressure is normal pressure or higher than normal pressure but not higher than 10KPa, and the reaction temperature is 50-70°C. A solution containing 3.0wt% to 6.0wt% of chloropropanol is generated, and the solution contains hydrochloric acid with an equimolar concentration to the chloropropanol. The NaOH electrolyte inlet is connected to the stripping tower through a pipeline causticizing reactor, forming a causticizing subsystem. The concentration of NaOH electrolyte is 10wt% to 20wt%, the molar ratio of sodium hydroxide to chloropropanol + hydrochloric acid is 1.0 to 1.2:1, the causticizing reaction temperature is controlled at 90 to 95°C, the reaction time is controlled at 0.5 to 2 seconds, the concentration of crude propylene oxide at the top of the stripping tower is 90wt% to 95wt%, the absolute pressure at the top of the stripping tower is 25 to 65Kpa, and the NaCl concentration in the causticized wastewater at the bottom of the stripping tower is 2.5wt% to 5.5wt%; the fore-distillation tower and the rectifying tower are connected in series to form a propylene oxide rectifying subsystem, the crude propylene oxide material first passes through the fore-distillation tower, the finished propylene oxide is discharged from the top of the fore-distillation tower, and the high-boiling point components are discharged from the top of the rectifying tower. The operating pressure of the distillation tower is atmospheric pressure, the bottom temperature of the tower is controlled at 50℃~85℃, and causticized wastewater is discharged from the bottom of the distillation tower; the high-pressure pump is connected to the supercritical delayed gasification reactor through an electromagnetic heating pipeline gasification reactor, the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor is respectively connected to the high-temperature purified water outlet of the gas-liquid separation tank, and a diluted brine outlet is provided under the salt discharge lock hopper, forming a causticized wastewater supercritical gasification device treatment subsystem; the diluted brine inlet is connected to the chlor-alkali electrolysis cell of the NaCl solution electrolysis subsystem, the chlorine outlet of the chlor-alkali electrolysis cell is connected to the chlorine dissolver of the chlorohydrin subsystem through a compressor, and the NaOH electrolyte outlet is connected to the pipeline causticizing reaction of the causticizing subsystem through a pressure pump. the chlorohydrinization subsystem is connected to the inlet of the pipeline causticizing reactor of the causticizing subsystem through the chlorohydrin solution outlet at the bottom of the flash tower, the crude alkylene oxide outlet at the top of the stripping tower of the causticizing subsystem is connected to the inlet of the fore-distillation tower of the alkylene oxide rectification subsystem, the causticized wastewater outlet at the bottom of the stripping tower is connected to the inlet of the electromagnetic heating pipeline gasification reactor of the causticizing wastewater treatment subsystem, and the waste liquid outlet of the tail gas scrubber of the chlorohydrinization subsystem and the causticized wastewater outlet at the bottom of the distillation tower of the propylene oxide rectification subsystem are also connected to the inlet of the electromagnetic heating pipeline gasification reactor; the salt discharge lock hopper at the bottom of the supercritical delayed gasification reactor of the causticizing wastewater treatment subsystem is connected to the chlor-alkali electrolysis cell of the NaCl solution electrolysis subsystem.

2. A clean production device for alkylene oxide chlorohydrin process based on closed-loop chlorine recycling according to claim 1, characterized in that The chlorine dissolver is a microporous pipe chlorine dissolver, a jet pump chlorine dissolver or a T-type straight pipe chlorine dissolver.

3. The clean production device of alkylene oxide chlorohydrin process based on closed-loop chlorine recycling according to claim 1, characterized in that The propylene distributor is a microporous pipeline mixer or a jet pump mixer, and the chlorohydrinization reactor is a pipeline reactor with an internal mixing element reinforcement, a single-tower chlorohydrin reactor, a single-tower multi-tower chlorohydrin reactor in series, a tube-tower chlorohydrin reactor or a tubular reactor.

4. The clean production device of alkylene oxide chlorohydrin process based on closed-loop chlorine recycling according to claim 1, characterized in that The causticizing reaction is carried out in a pipeline causticizing reactor, and the NaOH content in the causticizing wastewater is controlled at 0.01 wt% to 1.3 wt%.

5. The clean production device of alkylene oxide chlorohydrin process based on closed-loop chlorine recycling according to claim 1, characterized in that In the caustic wastewater supercritical gasification device treatment subsystem, the caustic wastewater at the bottom of the stripping tower is pressurized to ≥22.1MPa by a high-pressure pump, and then heat exchanged with the supercritically gasified synthesis gas and supercritical high-temperature purified water mixed phase; the preheated caustic waste liquid is heated to 400-700℃ by an electromagnetic heating tubular reactor for supercritical gasification reaction, and the supercritical gasified gas and liquid enter the supercritical delayed gasification reactor and stay for 1-180 minutes to generate a mixture of synthesis gas and supercritical high-temperature purified water and a high-concentration NaCl slurry; the extracted synthesis gas and supercritical high-temperature purified water mixed phase are heat exchanged with the high-pressure dissolved oxygen caustic waste liquid, and the gas and liquid are separated, the synthesis gas is discharged, and the purified water is reused; the high-concentration Na The Cl slurry is switched through the bottom lock hopper of the supercritical delayed gasification reactor and diluted with partially purified water to a concentrated brine of 31.5wt%-36.1wt% before being returned to the electrolyzer for recycling. The electromagnetic heating tubular reactor is configured such that, under the action of an electromagnetic heating controller, high-frequency alternating current passes through a coil to generate an alternating magnetic field, causing eddy currents to form and self-heat the tubular reactor wall and internal self-mixing reinforcement components. The self-mixing reinforcement components are structured packing, X-cross plate type, or spiral plate type. A funnel-shaped liquid extraction port is provided at the center of the supercritical delayed gasification reactor, the funnel being connected to the upper portion of the reactor. A gas-liquid mixed phase discharge port is provided at the top of the reactor, and two or more salt discharge lock hoppers are provided at the bottom of the reactor.

6. The clean production device of alkylene oxide chlorohydrin process based on closed-loop recycling of chlorine according to claim 1, characterized in that The chlor-alkali electrolyzer is an oxygen anion membrane electrolyzer or an anion membrane electrolyzer.

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