A PTA oxidation reaction process water recovery system

Abstract

The invention discloses a PTA oxidation reaction process water recovery system, which belongs to the technical field of process water recovery systems. The system comprises an oxidation reactor, a heat exchanger and a boiler. The bottom discharge port of the oxidation reactor is connected to the liquid inlet on the left side of the heat exchanger through a pipeline, and a pump a and a valve are provided on the pipeline. The bottom discharge port of a gas-liquid distillation tower is connected to a cooling device through a pipeline, and a pump c and a valve are provided on the pipeline. A slurry filter is provided downstream of the cooling device. The cooling device is connected to the liquid inlet on the top of the slurry filter through a pipeline, and a pressure reducing valve is provided on the pipeline. A steam ejector is provided on the lower side of the slurry filter. The steam outlet on the top of the gas-liquid distillation tower is connected to the steam inlet on the top of the steam ejector through a pipeline, and a valve is provided on the pipeline. The discharge port at the bottom of the slurry filter is connected to a mixing port on the left side of the steam ejector through a pipeline, and a valve is provided on the pipeline. The process flow of the invention is simple, and the problem of unsmooth slurry discharge and easy blockage in the slurry filter is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of process water recovery systems, in particular to a PTA oxidation reaction process water recovery system. Background Art

[0002] Currently, the petrochemical industry has significantly improved the utilization of low-temperature waste heat through measures such as optimizing heat exchange processes in process units and coupling heat sources from upstream and downstream units. Furthermore, by learning from and introducing foreign experience and related equipment in low-temperature waste heat recovery, low-temperature waste heat has gradually been used for heating, power generation, and refrigeration. Despite this, some chemical plants still directly discharge a large amount of low-temperature waste heat below 150°C due to the large number of heat sources and heat sinks, their widespread distribution, and energy level mismatches. Therefore, existing technologies reuse the heat generated in the process water after the PTA (para-tert-butyl tert-butyl) oxidation reaction. After utilization, the process water is cooled to recover the catalyst and solvent in the process water. In addition to the process water produced by the PTA reaction, it also contains nitrogen, acetic acid vapor, and water vapor. After cooling, the process water is separated into a slurry, and the process water containing only the catalyst and solvent is recovered. The slurry separation is performed in a slurry filter. However, due to the slurry's high viscosity, the existing technology often causes slurry to clog the filter outlet after separation, hindering production. Summary of the Invention

[0003] In order to solve the technical problems mentioned in the above background technology, the present invention provides a PTA oxidation reaction process water recovery system, and the technical solution adopted is as follows:

[0004] The invention comprises an oxidation reactor, a heat exchanger and a boiler. The bottom discharge port of the oxidation reactor is connected to the liquid inlet on the left side of the heat exchanger through a pipeline, and a pump a and a valve are provided on the pipeline. A water inlet pipeline is provided on the upper part of the heat exchanger, and the upper water outlet of the heat exchanger is connected to the water inlet of the boiler through a pipeline. The invention is characterized in that a gas-liquid distillation tower is provided on one side of the heat exchanger, the liquid outlet of the heat exchanger is connected to the liquid inlet of the gas-liquid distillation tower through a pipeline, and a pump b and a valve are provided on the pipeline. A cooling device is provided on one side of the gas-liquid distillation tower, and the bottom discharge port of the gas-liquid distillation tower is connected to the liquid inlet of the gas-liquid distillation tower through a pipeline. The liquid port is connected to the cooling device through a pipeline and a pump c and a valve are provided on the pipeline. A slurry filter is provided downstream of the cooling device. The cooling device is connected to the upper liquid inlet of the slurry filter through a pipeline and a pressure reducing valve is provided on the pipeline. A steam ejector is provided on the lower side of the slurry filter. The steam outlet on the upper part of the gas-liquid distillation tower is connected to the steam inlet on the upper part of the steam ejector through a pipeline and a valve is provided on the pipeline. The discharge port at the bottom of the slurry filter is connected to the mixing port on the left part of the steam ejector through a pipeline and a valve is provided on the pipeline.

[0005] Preferably, the cooling device includes a gas-liquid cooler, a process water collecting tank and a process water cooler, the bottom liquid outlet of the gas-liquid distillation tower is connected to the left liquid inlet of the gas-liquid cooler through a pipeline, and a pump c and a valve are provided on the pipeline, the right liquid outlet of the gas-liquid cooler is connected to the left liquid inlet of the process water collecting tank through a pipeline, the bottom liquid outlet of the process water collecting tank is connected to the left liquid inlet of the process water cooler through a pipeline, and a pump d and a valve are provided on the pipeline, the right liquid outlet of the process water cooler is connected to the upper liquid inlet of the slurry filter through a pipeline, and a pressure reducing valve is provided on the pipeline.

[0006] Preferably, the upper steam outlet of the process water collection tank is connected to the upper steam inlet of the gas-liquid cooler through a pipeline.

[0007] Preferably, a filtrate collecting tank is provided on one side of the slurry filter, and the left liquid outlet of the slurry filter is connected to the right liquid inlet of the filtrate collecting tank through a pipeline, and a valve is provided on the pipeline.

[0008] Preferably, a pipeline is provided at the bottom liquid outlet of the filtrate collecting tank and a pump e and a valve are provided on the pipeline.

[0009] Preferably, a filter cake beater is provided at the lower side of the steam jet vacuum pump, and the bottom discharge port of the steam jet vacuum pump is connected to the upper feed port of the filter cake beater through a pipeline.

[0010] Preferably, the bottom liquid outlet of the filter cake beater is connected to the pipeline on the left liquid outlet of the slurry filter through a pipeline, and a pump f and a valve are provided on the pipeline.

[0011] The present invention has the following advantages: after the PAT reaction, the high-temperature process water exchanges heat with the heat exchanger to recover the heat and supply it to the boiler for use, and then enters the gas-liquid distillation tower. On the one hand, when the process water is recovered, the gas-liquid distillation tower first separates out the unnecessary nitrogen, water vapor, etc. in the process water. On the other hand, the vapor-state catalyst and solvent and other heavy components carried by the nitrogen and water vapor are liquefied and merged into the process water. After the nitrogen and water vapor are removed, the process water is cooled by the cooling device to form a part of the impurities therein into slurry. The process water with slurry is slowly passed through the pressure reducing valve into the slurry filter to remove the slurry in the process water, and finally the required recovery is obtained. The collected process water, whose main components are catalyst and solvent, enters the steam jet aspirator through the mixing port of the steam jet aspirator after filtration in the slurry filter. In this process, the unnecessary nitrogen and water vapor that have been excluded are introduced into the steam jet aspirator. Since the nitrogen and water vapor enter the steam jet aspirator and become high-pressure jets, a high vacuum is generated in the steam jet aspirator. Under negative pressure conditions, the viscous and difficult-to-discharge slurry in the slurry filter can be smoothly pushed into the steam jet aspirator under high pressure, and the mixed nitrogen and water vapor are discharged through the bottom of the steam jet aspirator. The process flow of the present invention is simple, and solves the problem of smooth slurry discharge and easy blockage in the slurry filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a system flow chart of the present invention.

[0013] Figures: 1 oxidation reactor, 2 heat exchanger, 3 boiler, 4 pump a, 5 gas-liquid distillation tower, 6 pump b, 7 pump c, 8 slurry filter, 9 pressure reducing valve, 10 steam ejector, 11 gas-liquid cooler, 12 process water collecting tank, 13 process water cooler, 14 pump d, 15 filtrate collecting tank, 16 pump e, 17 filter cake beater, 18 pump f.

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example

[0015] Please refer to Figure 1 :

[0016] The present invention provides a PTA oxidation reaction process water recovery system, comprising an oxidation reactor 1, a heat exchanger 2 and a boiler 3. The bottom discharge port of the oxidation reactor 1 is connected to the liquid inlet on the left side of the heat exchanger 1 through a pipeline, and a pump a4 and a valve are provided on the pipeline. The process water generated after the reaction in the oxidation reactor 1 enters the heat exchanger 2 through the pipeline. A water inlet pipeline is provided on the upper part of the heat exchanger 2. Boiler water enters the heat exchanger 2 through the water inlet pipeline and performs heat exchange with the process water in the heat exchanger 2, so that the boiler water is preheated. The upper water outlet of the heat exchanger 2 is connected to the water inlet of the boiler 3 through a pipeline, and the preheated boiler water enters the boiler. In this process, heat recovery and utilization of the process water are achieved. The point is that a gas-liquid distillation tower 5 is provided on one side of the heat exchanger 2, and the process water after heat exchange enters the gas-liquid distillation tower 5. On the one hand, when the process water is recovered, the gas-liquid distillation tower 5 first separates out unnecessary nitrogen, water vapor, etc. in the process water. On the other hand, the vapor-state catalysts and solvents and other heavy components carried in the nitrogen and water vapor are liquefied and merged into the process water. The liquid outlet of the heat exchanger 2 is connected to the liquid inlet of the gas-liquid distillation tower 5 through a pipeline, and a pump b6 and a valve are provided on the pipeline. A cooling device is provided on one side of the gas-liquid distillation tower 5, and the liquid outlet at the bottom of the gas-liquid distillation tower 5 is connected to the cooling device through a pipeline, and a pump c7 and a valve are provided on the pipeline. The process water in the gas-liquid distillation tower 5 from which nitrogen and water vapor have been removed enters the cooling device. Internal cooling is used to cool the process water from which nitrogen and water vapor have been removed, so that part of the impurities therein form slurry. A slurry filter 8 is provided downstream of the cooling device. The cooling device is connected to the upper liquid inlet of the slurry filter 8 through a pipeline, and a pressure reducing valve 9 is provided on the pipeline. The pressure reduction of the pressure reducing valve 9 allows the process water with slurry to slowly enter the slurry filter 8, so that the process water can fully separate from the slurry after entering the slurry filter 8, and finally obtain the process water whose main components are catalyst and solvent that need to be recovered. A steam ejector 10 is provided on the lower side of the slurry filter 8, and the steam outlet on the upper part of the gas-liquid distillation tower 5 is connected to the steam inlet on the upper part of the steam ejector 10 through a pipeline. A valve is provided on the pipeline, and the discharge port at the bottom of the slurry filter 8 is connected to the mixing port on the left side of the steam ejector 10 through a pipeline, and a valve is provided on the pipeline. The slurry filtered in the slurry filter 8 enters the steam ejector 10 through the mixing port of the steam ejector 10. This process utilizes the unnecessary nitrogen and water vapor that are eliminated to pass into the steam ejector 10. Since the nitrogen and water vapor enter the steam ejector 10 and become high-pressure jets, a high vacuum is generated in the steam ejector 10. Under negative pressure conditions, the viscous and difficult-to-discharge slurry in the slurry filter 10 can smoothly enter the steam ejector 10 under high-pressure push and the mixed nitrogen and water vapor are discharged through the bottom of the steam ejector 10.

[0017] The cooling device includes a gas-liquid cooler 11, a process water collecting tank 12 and a process water cooler 13. The bottom liquid outlet of the gas-liquid distillation tower 5 is connected to the left liquid inlet of the gas-liquid cooler 11 through a pipeline, and a pump c7 and a valve are provided on the pipeline. The right liquid outlet of the gas-liquid cooler 11 is connected to the left liquid inlet of the process water collecting tank 12 through a pipeline. The bottom liquid outlet of the process water collecting tank 12 is connected to the left liquid inlet of the process water cooler 13 through a pipeline, and a pump d14 and a valve are provided on the pipeline. The right liquid outlet of the process water cooler 13 is connected to the upper liquid inlet of the slurry filter 8 through a pipeline, and a pressure reducing valve 9 is provided on the pipeline. The process water first enters the gas-liquid cooler 11 to liquefy the process water and some residual water vapor, and no gaseous state remains. Then it enters the process collecting tank 12 for collection, and then enters the process water cooler 13 for further cooling at a lower temperature, so that some of the impurities therein form a slurry.

[0018] The upper steam outlet of the process water collecting tank 12 is connected to the upper steam inlet of the gas-liquid cooler 11 through a pipeline, and the unliquefied water vapor in the process water collecting tank 12 is returned to the gas-liquid cooler 11 through the pipeline for further liquefaction.

[0019] A filtrate collecting tank 15 is provided on one side of the slurry filter 8. The left liquid outlet of the slurry filter 8 is connected to the right liquid inlet of the filtrate collecting tank 15 through a pipeline, and a valve is provided on the pipeline. The process water after the slurry is filtered out in the slurry filter 8 enters the filtrate collecting tank 15 through the pipeline and is collected.

[0020] A pipeline is provided at the liquid outlet at the bottom 15 of the filtrate collecting tank and a pump e16 and a valve are provided on the pipeline. The recovered process water in the filtrate collecting tank 15 is provided to the PTA oxidation reaction system through the pipeline for recycling.

[0021] A filter cake beater 17 is provided at the lower side of the steam jet aspirator 10. The bottom discharge port of the steam jet aspirator 10 is connected to the upper feed port of the filter cake beater 17 via a pipeline. The slurry passes through the steam jet aspirator and enters the filter cake beater for cake making and extrusion. The process water carried in the slurry can be squeezed out and recycled, reducing resource waste.

[0022] The bottom liquid outlet of the filter cake beater 17 is connected to the pipeline on the left liquid outlet of the slurry filter 8 through a pipeline, and a pump f18 and a valve are provided on the pipeline. The process water squeezed out by the filter cake beater 17 is merged into the pipeline on the left liquid outlet of the slurry filter 8 through the pipeline and recovered together into the filtrate collection tank 15.

[0023] Working principle of the present invention:

[0024] Open the valve and pump a4 on the pipeline. The high-temperature process water obtained after the reaction in the oxidation reactor 1 enters the heat exchanger 2 through the pipeline. At the same time, the boiler water enters the heat exchanger 2 through the water inlet pipeline to exchange heat with the process water in the heat exchanger 2. It is worth noting that the process water does not mix with the boiler water in the heat exchanger 2 in the heat exchange tubes in the heat exchanger 2. Heat is only exchanged through the heat exchange tubes. The boiler water after heat exchange enters the boiler 3 through the pipeline on the upper part of the heat exchanger 2. Open the valve and pump b6. The process water in the heat exchanger 2 enters the gas-liquid distillation tower 5 through the pipeline on the right side of the heat exchanger 2. Under the action of the gas-liquid distillation tower 5, on the one hand, When the process water is recovered, the gas-liquid distillation tower 5 is used to separate the unnecessary nitrogen, water vapor, etc. in the process water. On the other hand, the heavy components such as the catalyst and solvent carried by the nitrogen and water vapor are liquefied and merged into the process water. The valve and pump c7 are opened, and the process water from the gas-liquid distillation tower 5, which has been freed of nitrogen and water vapor, enters the gas-liquid cooler 11. After cooling, the process water and some of the residual water vapor are liquefied. The process water then enters the process water collection tank 12 to be collected, and then enters the process water cooler 13 to make some of the impurities in the process water form a slurry. The pressure reducing valve 9 is opened to allow the cooling water with the slurry to slowly enter the slurry process. In the filter 8, the slurry is filtered by the slurry filter 8 and remains in the slurry filter 8. The valve is opened and the process water in the slurry filter 8 that has been freed of slurry is passed through the pipeline into the filtrate collection tank 15 to be collected. At this time, the process water is a filtrate containing catalyst and solvent as main components. In this process, the valve is opened and the slurry in the slurry filter 8 is passed through the pipeline into the steam ejector 10 through the mixing port of the steam ejector 10, and the unnecessary nitrogen and water vapor that were originally excluded from the gas-liquid distillation tower 5 are passed into the steam ejector 10. The nitrogen and water vapor that enter the steam ejector 10 are used to form high-pressure jets, so that the steam ejector A high vacuum is generated in the device 10. Under negative pressure conditions, the viscous slurry in the slurry filter 10 that is difficult to discharge can smoothly enter the steam ejector 10 under high pressure and be mixed with nitrogen and water vapor and discharged from the bottom of the steam ejector 10. The slurry, nitrogen, water vapor, etc. discharged from the steam ejector 10 enter the filter cake beater 17 through pipelines, and the nitrogen and water vapor are discharged through other pipelines of the filter cake beater 17. The remaining slurry in the filter cake beater 17 is squeezed by the cake beater to squeeze out process water from the slurry, and then merged into the pipeline on the left liquid outlet of the slurry filter 8 through the pipeline, and recovered together into the filtrate collection tank 15.

[0025] The present invention is simple to operate, easy to use, and suitable for comprehensive promotion and application. Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A PTA oxidation reaction process water recovery system, comprising an oxidation reactor (1), a heat exchanger (2) and a boiler (3), wherein the bottom discharge port of the oxidation reactor (1) is connected to the left liquid inlet of the heat exchanger (1) via a pipeline, and a pump a (4) and a valve are provided on the pipeline, and a water inlet pipeline is provided on the upper portion of the heat exchanger (2), and the upper water outlet of the heat exchanger (2) is connected to the water inlet of the boiler (3) via a pipeline, characterized in that: A gas-liquid distillation tower (5) is provided on one side of the heat exchanger (2), the liquid outlet of the heat exchanger (2) is connected to the liquid inlet of the gas-liquid distillation tower (5) through a pipeline, and a pump b (6) and a valve are provided on the pipeline. A cooling device is provided on one side of the gas-liquid distillation tower (5), the liquid outlet at the bottom of the gas-liquid distillation tower (5) is connected to the cooling device through a pipeline, and a pump c (7) and a valve are provided on the pipeline. A slurry filter (8) is provided downstream of the cooling device, the cooling device is connected to the upper liquid inlet of the slurry filter (8) through a pipeline, and a pressure reducing valve (9) is provided on the pipeline. A steam ejector (10) is provided on the lower side of the slurry filter (8), the steam outlet at the top of the gas-liquid distillation tower (5) is connected to the steam inlet at the top of the steam ejector (10) through a pipeline, and a valve is provided on the pipeline. The discharge port at the bottom of the slurry filter (8) is connected to the mixing port on the left of the steam ejector (10) through a pipeline, and a valve is provided on the pipeline. The cooling device includes a gas-liquid cooler (11), a process water collecting tank (12) and a process water cooler (13). The bottom liquid outlet of the gas-liquid distillation tower (5) is connected to the left liquid inlet of the gas-liquid cooler (11) through a pipeline, and a pump c (7) and a valve are provided on the pipeline. The right liquid outlet of the gas-liquid cooler (11) is connected to the left liquid inlet of the process water collecting tank (12) through a pipeline. The bottom liquid outlet of the process water collecting tank (12) is connected to the left liquid inlet of the process water cooler (13) through a pipeline, and a pump d (14) and a valve are provided on the pipeline. The right liquid outlet of the process water cooler (13) is connected to the upper liquid inlet of the slurry filter (8) through a pipeline, and a pressure reducing valve (9) is provided on the pipeline.

2. A PTA oxidation reaction process water recovery system according to claim 1, characterized in that: The upper steam outlet of the process water collecting tank (12) is connected to the upper steam inlet of the gas-liquid cooler (11) through a pipeline.

3. A PTA oxidation reaction process water recovery system according to claim 2, characterized in that: A filtrate collecting tank (15) is provided on one side of the slurry filter (8), and a left liquid outlet of the slurry filter (8) is connected to a right liquid inlet of the filtrate collecting tank (15) through a pipeline, and a valve is provided on the pipeline.

4. A PTA oxidation reaction process water recovery system according to claim 3, characterized in that: The liquid outlet at the bottom (15) of the filtrate collecting tank is provided with a pipeline, and a pump e (16) and a valve are provided on the pipeline.

5. A PTA oxidation reaction process water recovery system according to claim 4, characterized in that: A filter cake beater (17) is provided at the lower side of the steam ejector (10), and a discharge port at the bottom of the steam ejector (10) is connected to a feed port at the upper part of the filter cake beater (17) via a pipeline.

6. A PTA oxidation reaction process water recovery system according to claim 5, characterized in that: The bottom liquid outlet of the filter cake beater (17) is connected to the pipeline on the left liquid outlet of the slurry filter (8) through a pipeline, and a pump f (18) and a valve are provided on the pipeline.

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