CN118545792A - A method and device for treating propylene oxide wastewater - Google Patents

Abstract

The invention discloses a propylene oxide wastewater treatment method and a treatment device thereof. The treatment method comprises: step 1: mixing propylene oxide wastewater with an entrainer to form an azeotropic system for rectification to obtain a first gas phase and a first liquid phase; step 2: drawing a part of the first gas phase out of the azeotropic system and increasing the temperature and pressure to obtain a second gas phase; step 3: the first part of the first liquid phase exchanges heat with the second gas phase, and the first part of the first liquid phase after heat exchange is returned to the azeotropic system; the second part of the first liquid phase is discharged as concentrated wastewater; the second gas phase after heat exchange is condensed into a second liquid phase; the second liquid phase is phase-separated to obtain an entrainer phase and a water phase; the entrainer phase is returned to the azeotropic system, and the water phase is discharged as purified wastewater. The method improves the utilization efficiency of energy, reduces the production cost of propylene oxide, and has significant economic benefits.

Description

A method and device for treating propylene oxide wastewater

Technical Field

The invention relates to the field of chemical wastewater treatment, in particular to a propylene oxide wastewater treatment method and a treatment device thereof.

Background Art

Propylene oxide (PO) is an important basic organic chemical raw material, mainly used in the production of chemical products such as polyether polyols, propylene glycol and propylene glycol ethers, and is widely used in insulation materials, construction materials, elastomers, coatings and adhesives.

The direct oxidation of propylene oxide by hydrogen peroxide (HPPO) is a new green production process for propylene oxide. It has the advantages of simple process, small environmental impact, mild reaction conditions, and high raw material utilization efficiency. It is gradually replacing the traditional production process of propylene oxide. HPPO technology will produce wastewater containing propylene glycol monomethyl ether, propylene glycol isomonomethyl ether, propylene glycol and inorganic salts. Its COD value exceeds the standard and cannot be directly treated biochemically.

In order to meet the requirements of biochemical treatment, the wastewater generated by HPPO technology needs to be separated to obtain purified wastewater with very low content of propylene glycol and its monomethyl ether and no inorganic salts, and then discharged to the sewage treatment plant for biochemical treatment after simple treatment. Since propylene glycol monomethyl ether and propylene glycol isomonomethyl ether will form azeotropes with high water content with water, they cannot be separated and dehydrated by conventional distillation methods.

CN113072116B discloses a method for treating propylene oxide wastewater, wherein the wastewater is introduced into an alcohol concentration tower for concentration, the top gas of the alcohol concentration tower is compressed and introduced into the alcohol concentration tower reboiler as a heat source for heat exchange, and a heat coupling method is used to recover alcohol organic matter from the wastewater with low energy consumption. The method has low energy consumption, but does not consider the recovery of ether organic matter in the wastewater, and the difficulty of biochemical treatment of wastewater is still relatively large.

CN103342631B discloses a process for separating propylene glycol monomethyl ether aqueous solution by double membrane coupling technology, and improves the yield and purity of propylene glycol monomethyl ether by pervaporation technology. This method has strong practicality in small-scale production, but it is difficult to complete the separation task when the amount of ether-containing wastewater to be treated is large.

Summary of the invention

The purpose of the present invention is to provide a method for treating propylene oxide wastewater in view of the technical defects existing in the prior art. A heat pump distillation method combining heat pump distillation and azeotropic distillation is adopted to separate ether-water azeotrope which cannot be separated by conventional distillation, and at the same time, the separation energy consumption of propylene oxide wastewater is reduced.

Another object of the present invention is to provide a wastewater treatment device used in the above-mentioned propylene oxide wastewater treatment method.

The technical solution adopted to achieve the purpose of the present invention is:

A method for treating propylene oxide wastewater comprises the following steps:

Step 1: mixing propylene oxide wastewater with an azeotropic agent to form an azeotropic system for distillation to obtain a first gas phase and a first liquid phase;

Step 2: taking a portion of the first gas phase out of the azeotropic system and raising the temperature and pressure to obtain a second gas phase;

Step 3: The first part of the first liquid phase is heat exchanged with the second gas phase, and the first part of the first liquid phase after heat exchange is returned to the azeotropic system; the second part of the first liquid phase is discharged as concentrated wastewater; the second gas phase after heat exchange is condensed into a second liquid phase; the second liquid phase is phase-splitting to obtain an azeotropic agent phase and a water phase; the azeotropic agent phase is returned to the azeotropic system, and the water phase is discharged as purified wastewater;

When the amount of the first gas phase drawn out of the azeotropic system is the first preset required amount, the heat exchange amount of the obtained second gas phase is equal to the heat required by the first part of the first liquid phase, and the azeotropic system maintains equilibrium.

In the above technical solution, when the amount of the first gas phase drawn out of the azeotropic system is less than the first preset required amount, the third portion of the first liquid phase is returned to the azeotropic system after being heated;

When the supply amount of the first gas phase drawn out of the azeotropic system is greater than the first preset demand amount, at least a portion of the first gas phase drawn out of the azeotropic system is cooled and condensed before phase separation, the azeotropic agent phase after phase separation is returned to the azeotropic system, and the water phase after phase separation is discharged as purified wastewater.

In the above technical solution, the processing method further includes:

The amount of the first gas phase provided is adjusted according to the concentration of the alcohol-ether organic matter in the concentrated wastewater (ie, the total concentration of the alcohol organic matter and the ether organic matter).

In the above technical solution, the azeotropic agent is one or a mixture of benzene, toluene, ethylbenzene, cyclohexane, methylcyclohexane and ethylene dichloride.

In the above technical scheme, in step 1, the propylene oxide wastewater and the entrainer are mixed and distilled in a distillation tower; the distillation tower is a plate tower, a packed tower or a plate-packed mixed tower;

The number of plates of the distillation tower is 10-25, the top temperature of the distillation tower is 40-200° C., and the top pressure of the distillation tower is 60-900 kPa.

In the above technical solution, in step 2, the first gas phase of the azeotropic system is introduced and heated and pressurized by a compressor to obtain a second gas phase; the compressor is a Roots compressor, a centrifugal compressor or a screw compressor;

The compression ratio of the compressor is 1.1-8.

In the above technical solution, the mass content of alcohol organic matter in the propylene oxide wastewater is 0.033%-15%, the mass content of ether organic matter is 0.067%-30%, and the total mass content of alcohol organic matter and ether organic matter is 0.1%-40%.

The mass content of alcohol organic matter in the purified wastewater is less than 0.05%, and the mass content of ether organic matter is less than 500ppm.

The alcohol organic matter content in the concentrated wastewater is greater than 4%, and the ether organic matter content is greater than 22%;

The alcohol organic matter contains propylene glycol and at least one of ethylene glycol, dipropylene glycol, tripropylene glycol, glycerol, n-propanol and isopropanol; the ether organic matter includes propylene glycol monomethyl ether and propylene glycol isomonomethyl ether.

Another aspect of the present invention is to implement the above-mentioned treatment method through a propylene oxide wastewater treatment device;

The propylene oxide wastewater treatment device comprises a distillation tower, a compressor, a reboiler and a phase separation tank;

The distillation tower is used for mixed distillation of propylene oxide wastewater and an azeotropic agent to form a first gas phase and a first liquid phase; the top part of the distillation tower is provided with a gas phase outlet to separate the first gas phase;

The gas phase outlet is connected to the air inlet of the compressor, so that the first gas phase enters the compressor to increase temperature and pressure, forming a second gas phase;

The bottom part of the distillation tower is provided with a first liquid phase outlet to separate the first liquid phase; the first liquid phase outlet is connected to the refrigerant inlet of the reboiler, so that the first part of the first liquid phase enters the reboiler as a refrigerant for heat exchange and temperature increase; the refrigerant outlet of the reboiler is connected to the reboiler inlet of the distillation tower, so that the first part of the first liquid phase after heat exchange and temperature increase returns to the distillation tower; the bottom part of the distillation tower is provided with a second liquid phase outlet; the second part of the first liquid phase is discharged as concentrated wastewater through the second liquid phase outlet;

The gas outlet of the compressor is connected to the heat medium inlet of the reboiler, so that the second gas phase enters the reboiler as a heat medium for heat exchange and cooling; the heat medium outlet of the reboiler is connected to the phase separation tank, so that the second liquid phase obtained after heat exchange and cooling is separated in the phase separation tank;

The first outlet of the phase separation tank is connected to the top part of the distillation tower so that the entrainer phase obtained by phase separation returns to the azeotropic system; the water phase obtained by phase separation is discharged as purified waste water through the second outlet of the phase separation tank.

In the above technical solution, the wastewater treatment device further comprises an auxiliary reboiler, the refrigerant inlet of the auxiliary reboiler is connected to the third liquid phase outlet of the bottom part of the distillation tower, and the refrigerant outlet is connected to the reboiler inlet of the distillation tower; the third part of the first liquid phase enters the auxiliary reboiler through the third liquid phase outlet, is heated, and then returns to the azeotropic system;

and/or,

The wastewater treatment device also includes an auxiliary cooler, the heat medium inlet of the auxiliary cooler is connected to the gas phase outlet pipeline of the top part of the distillation tower, the heat medium outlet of the auxiliary cooler is connected to the phase separation tank, and a part of the first gas phase enters the auxiliary cooler through the gas phase outlet to be cooled and condensed into the second liquid phase.

In the above technical solution, the distillation tower is a plate tower, a packed tower or a plate-packed mixed tower;

The compressor is a Roots compressor, a centrifugal compressor or a screw compressor;

The reboiler and/or the auxiliary reboiler is one of a plate heat exchanger, a falling film evaporator, a forced circulation shell and tube heat exchanger, and a thermosyphon reboiler.

Compared with the prior art, the present invention has the following beneficial effects:

1. The propylene oxide wastewater treatment method provided by the present invention adopts a heat pump azeotropic distillation method to treat propylene oxide wastewater. The gas phase extracted from the top of the distillation tower is compressed and used as the heat medium of the reboiler. No additional fresh steam is required during normal operation. Compared with the traditional azeotropic distillation method, a large amount of circulating water and fresh steam consumption is saved, the energy utilization efficiency is improved, the production cost of propylene oxide is reduced, and significant economic benefits are achieved.

2. The propylene oxide wastewater treatment method provided by the present invention has a good treatment effect, wherein the alcohol organic matter content in the purified wastewater obtained by treatment is less than 0.05%, and the ether organic matter content is less than 500 ppm. The alcohol organic matter content in the concentrated wastewater obtained by treatment is greater than 4%, and the ether organic matter content is greater than 22%, and the recovery effect is good.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram showing the structure of a propylene oxide wastewater treatment device;

FIG2 is a schematic diagram of a distillation tower interface;

Figure 3 shows a schematic diagram of the reboiler interface.

In the figure: 1-distillation tower, 1-1-gas phase outlet, 1-2-first liquid phase outlet, 1-3-entrainer inlet, 1-4-reboiling inlet, 1-5-water inlet, 1-6-second liquid phase outlet, 1-7-third liquid phase outlet, 2-compressor, 2-1-air inlet, 2-2-air outlet, 3-reboiler, 3-1-heat medium inlet, 3-2-heat medium outlet, 3-3-refrigerant inlet, 3-4-refrigerant outlet, 4-phase separation tank, 4-1-inlet, 4-2-first outlet, 4-3-second outlet, 5-auxiliary reboiler, 6-auxiliary cooler.

DETAILED DESCRIPTION

The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

Example 1

A propylene oxide wastewater treatment device, as shown in FIG1 , comprises a distillation tower 1, a compressor 2, a reboiler 3 and a phase separation tank 4.

Wherein, the distillation tower is used for mixed distillation of propylene oxide wastewater and entrainer to form a first gas phase and a first liquid phase; the compressor 2 is used to compress and heat the first gas phase to form a second gas phase; the reboiler 3 is used for heat exchange between the second gas phase and the first part of the first liquid phase to condense the second gas phase to form a second liquid phase; the phase separation tank 4 is used for phase separation of the second liquid phase into an entrainer phase and a water phase. The top part of the distillation tower 1 is provided with a gas phase outlet 1-1; the bottom part of the distillation tower 1 is provided with a first liquid phase outlet 1-2 and a second liquid phase outlet 1-6; the distillation tower 1 is also provided with an entrainer inlet 1-3 and a reboiler inlet 1-4; the compressor 2 is provided with an air inlet 2-1 and an air outlet 2-2; the reboiler 3 is provided with a heat medium inlet 3-1, a heat medium outlet 3-2, a refrigerant inlet 3-3 and a refrigerant outlet 3-4; the phase separation tank 4 is provided with an inlet 4-1, a first outlet 4-2 and a second outlet 4-3.

The gas phase outlet 1-1 of the distillation tower 1 is connected to the air inlet 2-1 of the compressor 2 through a pipeline; the air outlet 2-2 of the compressor 2 is connected to the heat medium inlet 3-1 of the reboiler 3 through a pipeline; the heat medium outlet 3-2 of the reboiler 3 is connected to the inlet 4-1 of the phase separation tank 4 through a pipeline; the first outlet 4-2 of the phase separation tank 4 is connected to the azeotropic agent inlet 1-3 of the distillation tower 1 through a pipeline; the first liquid phase outlet 1-2 of the distillation tower 1 is connected to the refrigerant inlet 3-3 of the reboiler 3 through a pipeline; the refrigerant outlet 3-4 of the reboiler 3 is connected to the reboiler inlet 1-4 of the distillation tower 1 through a pipeline.

The propylene oxide wastewater treatment device also includes an auxiliary reboiler 5 and an auxiliary cooler 6. The refrigerant inlet of the auxiliary reboiler 5 is connected to the third liquid phase outlet 1-7 pipeline of the bottom part of the distillation tower 1, and the refrigerant outlet is connected to the reboiler inlet 1-4 pipeline of the distillation tower 1. The auxiliary reboiler 5 heats the third part of the first liquid phase by using fresh steam as a heat medium. One end of the auxiliary cooler 6 is connected to the gas phase outlet 1-1 pipeline of the top part of the distillation tower 1, and the other end is connected to the inlet 4-1 pipeline of the phase separation tank 4. The auxiliary cooler 6 condenses a part of the first gas phase by using circulating water as a refrigerant.

Example 2

In this embodiment, the composition and content of the propylene oxide wastewater are as follows, calculated by weight percentage: 1.6wt% propylene glycol monomethyl ether, 2.4wt% propylene glycol isomonomethyl ether, 0.8wt% propylene glycol, and 0.4wt% sodium sulfate.

A treatment method for a propylene oxide wastewater treatment device comprises the following steps:

Step 1: propylene oxide wastewater enters the distillation tower 1 through the water inlet 1-5 at a flow rate of 60 t/h; the entrainer benzene enters the distillation tower 1 through the entrainer inlet 1-3; the two are mixed and distilled in the distillation tower 1, and the distillation tower 1 adopts a plate tower with 16 plates; the distillation forms azeotropic tower top vapor (i.e., the first gas phase) and tower bottom liquid (i.e., the first liquid phase) at 139° C. and 800 kPa;

Step 2: a portion of the obtained azeotropic tower top gas enters the compressor 2 along the pipeline through the gas phase outlet 1-1; the power of the compressor 2 is 4423KW, and the compression ratio is 1.6; after compression and temperature increase, a compressed azeotropic steam (i.e., the second gas phase) of 169°C and 1300kPa is obtained;

Step 3: The obtained compressed azeotropic steam enters the reboiler 3 along the pipeline through the gas outlet 2-2 of the compressor 2, and is used as a heat medium to exchange heat and cool in the reboiler 3 to obtain condensate, i.e., the second liquid phase;

The first part of the bottom liquid in the distillation tower 1 enters the reboiler 3 through the first liquid phase outlet 1-2, and is heated and reboiled in the reboiler 3 as a refrigerant; the gas-liquid mixed phase after reboiled flows back to the distillation tower 1 through the reboiler inlet 1-4; the second part of the bottom liquid in the distillation tower 1 is discharged as concentrated wastewater through the second liquid phase outlet 1-6;

Step 4: The obtained second liquid phase flows out through the heat medium outlet 3-2 and enters the inlet 4-1 of the phase separation tank 4 along the pipeline; it is separated into two phases in the phase separation tank 4; one phase is the azeotropic agent phase, which flows back to the distillation tower 1 along the pipeline through the first outlet 4-2 of the phase separation tank 4 for recovery; the other phase is the water phase, which is discharged as purified wastewater through the second outlet 4-3 of the phase separation tank 4.

The mass content of alcohol organic matter in the purified wastewater was 0.006%, and the mass content of ether organic matter was 40ppm;

The mass content of alcohol organic matter in the obtained concentrated wastewater is 4.6%, and the mass content of ether organic matter is 25%.

In the above treatment method, the power of compressor 2 is 4423KW; the industrial electricity is calculated at 0.8 yuan/kW·h, and the equivalent cost is 3538 yuan/h; combined with the flow rate of propylene oxide wastewater, the cost of treating each ton of wastewater is 59 yuan.

Example 3

In this embodiment, the composition and content of the propylene oxide wastewater are as follows, calculated by weight percentage: 1.6wt% propylene glycol monomethyl ether, 2.4wt% propylene glycol isomonomethyl ether, 0.8wt% propylene glycol, and 0.4wt% sodium sulfate.

A treatment method for a propylene oxide wastewater treatment device comprises the following steps:

Step 1: propylene oxide wastewater enters the distillation tower 1 through the water inlet 1-5 at a flow rate of 60 t/h; the entrainer toluene enters the distillation tower 1 through the entrainer inlet 1-3; the two are mixed and distilled in the distillation tower 1, and the distillation tower 1 adopts a plate tower with 16 plates; the distillation forms azeotropic tower top vapor (i.e., the first gas phase) and tower bottom liquid (i.e., the first liquid phase) at 152°C and 800 kPa;

Step 2: a portion of the obtained azeotropic tower top gas enters the compressor 2 along the pipeline through the gas phase outlet 1-1; the power of the compressor 2 is 2860KW, and the compression ratio is 1.6; after compression and temperature increase, the compressed azeotropic steam (i.e., the second gas phase) of 181°C and 1260kPa is obtained;

Step 3: The obtained compressed azeotropic steam enters the reboiler 3 along the pipeline through the gas outlet 2-2 of the compressor 2, and is used as a heat medium to exchange heat and cool in the reboiler 3 to obtain condensate, i.e., the second liquid phase;

The first part of the bottom liquid in the distillation tower 1 enters the reboiler 3 through the outlet 1-2 of the bottom part, and is heated and reboiled in the reboiler 3 as a refrigerant; the gas-liquid mixed phase after reboiled flows back to the distillation tower 1 through the reboiler inlet 1-4; the second part of the bottom liquid in the distillation tower 1 is discharged as concentrated wastewater through the second liquid phase outlet 1-6;

Step 4: The obtained second liquid phase flows out through the heat medium outlet 3-2 and enters the inlet 4-1 of the phase separation tank 4 along the pipeline; it is divided into two phases in the phase separation tank 4; one phase is the azeotropic agent phase, which flows back to the distillation tower 1 along the pipeline through the first outlet 4-2 of the phase separation tank 4 for recovery; the other phase is the water phase, which is discharged through the second outlet 4-3 of the phase separation tank 4 as purified waste water.

The mass content of alcohol organic matter in the purified wastewater is 0.005%, and the mass content of ether organic matter is 100ppm;

The mass content of alcohol organic matter in the obtained concentrated wastewater is 4.9%, and the mass content of ether organic matter is 24%.

In the above treatment method, the power of compressor 2 is 2860KW; the industrial electricity is calculated at 0.8 yuan/kW·h, and the equivalent cost is 2288 yuan/h; combined with the flow rate of propylene oxide wastewater, the cost of treating each ton of wastewater is 38 yuan.

Using the traditional azeotropic distillation method, to complete the treatment of 60t/h of propylene oxide wastewater, at least four stages of azeotropic distillation are required, and at least 36t/h of fresh steam is required; the equivalent cost is 9,000 yuan/h; combined with the propylene oxide wastewater flow rate, the cost of treating each ton of wastewater is 150 yuan.

Example 4

A control method for a propylene oxide wastewater treatment device controls the supply amount of a first gas phase to be a first preset demand amount, so that the second gas phase can just provide heat for the first part of the first liquid phase to reboil, so that the device as a whole remains balanced without the need for additional fresh steam.

When the device is started or the operating load needs to be increased, the concentration of alcohol ether organic matter in the concentrated wastewater is low, and additional heat needs to be supplied through the auxiliary reboiler 5, thereby increasing the supply of the first gas phase and increasing the concentration of alcohol ether organic matter in the concentrated wastewater. When the device is stopped or the operating load is reduced, the concentration of alcohol ether organic matter in the concentrated wastewater is high, and cooling needs to be supplied through the auxiliary cooling device 6, thereby reducing the supply of the first gas phase and reducing the concentration of alcohol ether organic matter in the concentrated wastewater. The concentration of alcohol ether organic matter in the concentrated wastewater is adjusted by the auxiliary reboiler 5 and the auxiliary cooling device 6 to ensure that the heat required for reboiling the first part of the bottom liquid passing through the reboiler 3 is equal to the cooling required for liquefaction of the second gas phase.

The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (10)

1. A method for treating propylene oxide wastewater, comprising the following steps: Step 1: mixing propylene oxide wastewater with an azeotropic agent to form an azeotropic system for distillation to obtain a first gas phase and a first liquid phase; Step 2: taking a portion of the first gas phase out of the azeotropic system and raising the temperature and pressure to obtain a second gas phase; Step 3: The first part of the first liquid phase is heat exchanged with the second gas phase, and the first part of the first liquid phase after heat exchange is returned to the azeotropic system; the second part of the first liquid phase is discharged as concentrated wastewater; the second gas phase after heat exchange is condensed into a second liquid phase; the second liquid phase is phase-splitting to obtain an azeotropic agent phase and a water phase; the azeotropic agent phase is returned to the azeotropic system, and the water phase is discharged as purified wastewater; When the amount of the first gas phase drawn out of the azeotropic system is the first preset required amount, the heat exchange amount of the obtained second gas phase is equal to the heat required by the first part of the first liquid phase, and the azeotropic system maintains equilibrium. 2. The method for treating propylene oxide wastewater according to claim 1, wherein: When the amount of the first gas phase drawn out of the azeotropic system is less than the first preset required amount, the third portion of the first liquid phase is heated and then returned to the azeotropic system; When the supply amount of the first gas phase drawn out of the azeotropic system is greater than the first preset demand amount, at least a portion of the first gas phase drawn out of the azeotropic system is cooled and condensed before phase separation, the azeotropic agent phase after phase separation is returned to the azeotropic system, and the water phase after phase separation is discharged as purified wastewater. 3. The propylene oxide wastewater treatment method according to claim 2, characterized in that the treatment method further comprises: The amount of the first gas phase provided is adjusted according to the concentration of the alcohol ether organic matter in the concentrated wastewater. 4. The method for treating propylene oxide wastewater according to claim 1, wherein the entrainer is one or a mixture of benzene, toluene, ethylbenzene, cyclohexane, methylcyclohexane and ethylene dichloride. 5. The method for treating propylene oxide wastewater according to claim 1, characterized in that in step 1, the propylene oxide wastewater and the entrainer are mixed and distilled in a distillation tower; the distillation tower is a plate tower, a packed tower or a plate-packed mixed tower. 6. The method for treating propylene oxide wastewater according to claim 1, characterized in that in step 2, the first gas phase drawn out of the azeotropic system is heated and pressurized by a compressor to obtain a second gas phase; the compressor is a Roots compressor, a centrifugal compressor or a screw compressor. 7. The treatment method according to any one of claims 1 to 6, characterized in that the mass content of alcohol organic matter in the propylene oxide wastewater is 0.033%-15%, the mass content of ether organic matter is 0.067%-30%, and the total mass content of alcohol organic matter and ether organic matter is 0.1%-40%. The mass content of alcohol organic matter in the purified wastewater is less than 0.05%, and the mass content of ether organic matter is less than 500ppm. The mass content of alcohol organic matter in the concentrated wastewater is greater than 4%, and the mass content of ether organic matter is greater than 22%. 8. A propylene oxide wastewater treatment device, characterized in that the treatment method according to any one of claims 1 to 7 is implemented by the propylene oxide wastewater treatment device; The propylene oxide wastewater treatment device comprises a distillation tower, a compressor, a reboiler and a phase separation tank; The distillation tower is used for mixed distillation of propylene oxide wastewater and an azeotropic agent to form a first gas phase and a first liquid phase; the top part of the distillation tower is provided with a gas phase outlet to separate the first gas phase; The gas phase outlet is connected to the air inlet of the compressor, so that the first gas phase enters the compressor to increase temperature and pressure, forming a second gas phase; The bottom part of the distillation tower is provided with a first liquid phase outlet to separate the first liquid phase; the first liquid phase outlet is connected to the refrigerant inlet of the reboiler, so that the first part of the first liquid phase enters the reboiler as a refrigerant for heat exchange and temperature increase; the refrigerant outlet of the reboiler is connected to the reboiler inlet of the distillation tower, so that the first part of the first liquid phase after heat exchange and temperature increase returns to the distillation tower; the bottom part of the distillation tower is provided with a second liquid phase outlet; the second part of the first liquid phase is discharged as concentrated wastewater through the second liquid phase outlet; The gas outlet of the compressor is connected to the heat medium inlet of the reboiler, so that the second gas phase enters the reboiler as a heat medium for heat exchange and cooling; the heat medium outlet of the reboiler is connected to the phase separation tank, so that the second liquid phase obtained after heat exchange and cooling is separated in the phase separation tank; The first outlet of the phase separation tank is connected to the top part of the distillation tower so that the entrainer phase obtained by phase separation returns to the azeotropic system; the water phase obtained by phase separation is discharged as purified waste water through the second outlet of the phase separation tank. 9. The propylene oxide wastewater treatment device according to claim 8, characterized in that the wastewater treatment device further comprises an auxiliary reboiler, the refrigerant inlet of the auxiliary reboiler is connected to the third liquid phase outlet of the bottom part of the distillation tower, and the refrigerant outlet is connected to the reboiler inlet of the distillation tower; the third part of the first liquid phase enters the auxiliary reboiler through the third liquid phase outlet, is heated, and then returns to the azeotropic system; and/or, The wastewater treatment device also includes an auxiliary cooler, the heat medium inlet of the auxiliary cooler is connected to the gas phase outlet pipeline of the top part of the distillation tower, the heat medium outlet of the auxiliary cooler is connected to the phase separation tank, and a part of the first gas phase enters the auxiliary cooler through the gas phase outlet to be cooled and condensed into the second liquid phase. 10. The propylene oxide wastewater treatment device according to claim 9, characterized in that the distillation tower is a plate tower, a packed tower or a plate-packed mixed tower.