A nitrogen production device for continuous oxidation of tail gas by pseudotrimethylbenzene

Abstract

This invention discloses a nitrogen production device for continuous oxidation of trimellitic anhydride tail gas, within the field of liquid nitrogen or high-purity nitrogen preparation apparatus. The device includes a deacidification unit, a dehydration and drying unit, a nitrogen compression unit, and a liquefaction distillation unit. The nitrogen-rich tail gas from the continuous oxidation of trimellitic anhydride first enters an absorption tower, where CO2 and acetic acid are removed. It then passes through a molecular sieve adsorption tower to remove water and xylene, among other substances. The gas is then compressed by a nitrogen compressor and heat-exchanged in a second condenser to form low-temperature nitrogen. This nitrogen is then heat-exchanged again by a second heat exchange component to form liquid nitrogen or a vapor-liquid mixture, which enters a distillation tower. In the distillation tower, the nitrogen is repeatedly evaporated and condensed to further remove other impurities, simultaneously yielding liquid nitrogen and high-purity nitrogen products. This device effectively utilizes the tail gas from trimellitic anhydride production, enabling resource reuse and achieving better economic benefits.

Description

Technical Field

[0001] This invention relates to an apparatus for preparing liquid nitrogen or high-purity nitrogen, and particularly to an apparatus for producing nitrogen using the tail gas after continuous oxidation of pseudotrimethylbenzene. Background Technology

[0002] Currently, the production of liquid nitrogen and high-purity nitrogen mainly utilizes air separation units. Air separation units are industrial equipment used to separate the various gas components in air to obtain gases such as oxygen, nitrogen, and argon. The most common air separation method is cryogenic distillation, which uses a compression cycle to deeply freeze air into a liquid state. Based on the different boiling points of the components in the air, oxygen, nitrogen, and argon are gradually separated from the liquid air through cryogenic distillation.

[0003] The principle of air distillation is as follows: Due to differences in boiling points, the evaporation order of oxygen, nitrogen, and argon is: nitrogen > argon > oxygen, and the condensation order is: oxygen > argon > nitrogen. When a high-temperature saturated vapor comes into contact with a low-temperature saturated liquid phase, the vapor releases heat and partially condenses, while the liquid absorbs heat and partially evaporates. During partial condensation, a larger portion of the high-boiling-point oxygen component in the vapor condenses into the liquid phase, while a larger portion of the low-boiling-point nitrogen component in the liquid phase evaporates into the gas phase, increasing the nitrogen concentration in the gas phase and the oxygen concentration in the liquid phase. If this partial evaporation and partial condensation process is repeated multiple times, the nitrogen concentration in the gas phase continuously increases, and the oxygen concentration in the liquid phase continuously increases, ultimately achieving the separation of nitrogen and oxygen. The main equipment for this distillation is a distillation column. Each tray in the column provides a site for partial evaporation and partial condensation through gas-liquid contact, ultimately yielding high-purity nitrogen at the top and high-purity oxygen at the bottom.

[0004] CN103062990A discloses a liquid air separation unit, which includes a distillation column, which includes an upper column, a lower column, and a main condenser-evaporator. One of the product nitrogen outlets of the upper column is connected in sequence to the main heat exchanger and the product nitrogen output pipeline, and the other is connected in sequence to the liquefaction heat exchanger, the circulating nitrogen compressor, the booster end of the booster expander, the booster aftercooler, the liquefaction heat exchanger, the cryogenic air chiller unit, and the liquefaction heat exchanger.

[0005] CN102788476A discloses an air separation process for cryogenic air separation equipment that mainly produces high-purity nitrogen and byproduct liquid oxygen. The process steps are as follows: the raw air is filtered and purified and then divided into three paths; the first path directly enters the cold box, where the air exchanges heat with the return gas in the main heat exchanger and is cooled to the liquefaction temperature, then enters the nitrogen tower to participate in distillation to obtain pure nitrogen gas and liquid nitrogen products; the second path is pressurized by a turbine expander and cooled before entering the main heat exchanger to be cooled to the liquefaction temperature, then enters the nitrogen tower to participate in distillation to obtain pure nitrogen gas and oxygen-enriched liquid air; a portion of the oxygen-enriched air that enters the oxygen tower for distillation is further separated in the oxygen tower, then reheated after passing through a cooler and the main heat exchanger before exiting the fractionation tower; liquid oxygen product is obtained at the bottom of the oxygen tower; the third path, a small amount of air, goes to the instrument air system as instrument gas and sealing gas.

[0006] CN104296500A discloses an apparatus and method for cryogenic separation and purification of nitrogen and liquid nitrogen. The method uses air as the raw material. The air is sequentially compressed by an air compression system, cooled by a precooling system, and purified by a purification system to remove impurities before entering a fractionation tower system. The gas entering the fractionation tower system is divided into two parts: one part enters the pressurization end for pressurization, then passes through a cooler for heat exchange before entering the main heat exchanger. The air is then extracted from the lower part of the main heat exchanger and enters the expansion end for adiabatic expansion. The expanded air is reheated by the main heat exchanger and then sent out of the cold box. The other part of the air directly enters the main heat exchanger, is cooled to its liquefaction point, and then enters a single-stage distillation tower for distillation. The nitrogen product is extracted from the top of the single-stage distillation tower, reheated to room temperature by the main heat exchanger, and then enters the nitrogen collection unit through a valve. The liquid nitrogen product is extracted from the main cold liquid nitrogen side, passes through a liquid nitrogen subcooler where it exchanges heat with a small portion of the returning liquid nitrogen, is subcooled, and then enters the liquid nitrogen collection unit through a valve.

[0007] In existing technologies, trimellitic anhydride is produced by continuous oxidation of trimellitene in an oxygen-rich environment, with air as one of its raw materials. After the oxygen is consumed, medium-pressure nitrogen-rich tail gas is emitted, which is currently vented. The characteristics of the tail gas, with a nitrogen content of over 92% and an oxygen concentration of less than 0.5%, are not fully utilized to explore the economic value of the tail gas.

[0008] The shortcomings of existing technologies are: on the one hand, nitrogen separation from air is costly and energy-intensive; on the other hand, nitrogen that has been purified during the production of trimellitic anhydride is wasted and emitted, resulting in resource waste. Summary of the Invention

[0009] The purpose of this invention is to provide a nitrogen production device for continuous oxidation of pseudotrimethylbenzene tail gas, which can simultaneously produce liquid nitrogen and high-purity nitrogen gas using the tail gas generated by continuous oxidation of pseudotrimethylbenzene, so as to achieve full utilization of resources.

[0010] The objective of this invention is achieved as follows: a nitrogen production apparatus for continuous oxidation of pseudotrimethylbenzene tail gas, comprising a deacidification unit, a dehydration and drying unit, a nitrogen compression unit, and a liquefaction distillation unit; wherein,

[0011] The deacidification unit includes an absorption tower and a regeneration tower. The lower part of the absorption tower has a raw material inlet connected to the tail gas outlet of the continuous oxidation reactor for p-xylene. The top of the absorption tower is connected to the dehydration and drying unit via a top separator. The bottom outlet of the absorption tower is connected to the tube-side inlet of a lean-rich liquid heat exchanger. The tube-side outlet of the lean-rich liquid heat exchanger is connected to the upper-middle inlet of the regeneration tower. The top of the regeneration tower is connected to a top reflux tank via a condenser. The reflux port at the bottom of the top reflux tank is connected to the upper part of the regeneration tower via a reflux pipe. The top of the top reflux tank has a gas outlet. The bottom outlet of the regeneration tower is connected to the shell-side inlet of the lean-rich liquid heat exchanger. The shell-side outlet of the lean-rich liquid heat exchanger is connected to the upper part of the absorption tower via a lean liquid cooler.

[0012] Dehydration and drying unit: includes a molecular sieve desorption tower, the bottom inlet of which is connected to the top outlet of the top separator.

[0013] Nitrogen compression unit: includes a turbine and a nitrogen compressor. The turbine is driven to the nitrogen compressor, and the outlet of the nitrogen compressor is connected to the inlet of condenser two.

[0014] The liquefied distillation unit includes a heat exchange gas header and a distillation column. The heat exchange gas header is equipped with heat exchange component one and heat exchange component two. The inlet of heat exchange component one is connected to the top outlet of the molecular sieve desorption column, and the outlet of heat exchange component one is connected to the inlet of the nitrogen compressor. The inlet of heat exchange component two is connected to the outlet of condenser two, and the outlet of heat exchange component two is connected to the nitrogen inlet of the distillation column. The upper part of the distillation column is equipped with a nitrogen outlet, and the middle and lower parts are equipped with a liquid nitrogen outlet.

[0015] In operation, the nitrogen-rich tail gas from the continuous oxidation of trimellitic anhydride by air first enters an absorption tower to remove CO2 and acetic acid. It then passes through a molecular sieve adsorption tower to remove water and xylene, among other substances. The gas is then compressed by a nitrogen compressor and heat-exchanged in a second condenser to form low-temperature nitrogen. This nitrogen is then heat-exchanged again by a second heat exchange component to form liquid nitrogen or a vapor-liquid mixture, which enters a distillation tower. In the distillation tower, repeated evaporation and condensation further remove other impurities from the nitrogen, simultaneously yielding liquid nitrogen and high-purity nitrogen products. This device effectively utilizes the tail gas from trimellitic anhydride production for resource reuse, resulting in better economic benefits. Compared with existing technologies, the advantages of this invention are:

[0016] 1. Pseudotrimethylbenzene consumes oxygen during continuous oxidation by introducing air, and at the same time, it purifies nitrogen. Further purification of nitrogen can result in higher purity of the finished product, with liquid nitrogen purity ≥99.995% and nitrogen purity as high as 99.999%.

[0017] 2. Lower energy consumption: Conventional electric air separation and liquid air separation processes average approximately 600 kW / h per ton of product. Utilizing the nitrogen-rich tail gas from this project to produce air separation products is more energy-efficient than conventional all-electric air separation, achieving approximately 430 kW / h per ton of product, representing a 30% energy saving. This demonstrates significant energy efficiency and effective resource utilization.

[0018] Furthermore, the distillation column comprises a vertically arranged three-section column body, namely an upper column, a middle column, and a lower column. The diameter of the middle column is larger than that of the upper and lower columns. The upper column has several packing layers, with the nitrogen inlet located in the middle of the packing layers and the nitrogen outlet located above the packing layers. The middle column has at least two condensation heat exchange layers, each including a bottom plate, a baffle, and a cryogenic heat exchanger. The baffle is cylindrical and located on the upper side of the bottom plate, and the cryogenic heat exchanger is located within the space enclosed by the baffle. The bottom plate outside the baffle has several micropores penetrating the bottom plate. The lower column has several layers of baffle components, each including a horizontally arranged upper baffle and a lower baffle. The upper baffle extends above the lower baffle, and a longitudinal baffle is located on the lower baffle. A liquid nitrogen pool is formed between the longitudinal baffle, the lower baffle, and the inner wall of the column to contain liquid nitrogen. An overflow channel is formed between the longitudinal baffle and the upper baffle. The liquid nitrogen outlet is connected to one of the liquid nitrogen pools in the middle of the lower column. In this scheme, liquid nitrogen is in a vapor-liquid mixed state in the packing layer, and it continuously vaporizes and condenses, causing some impurity gases to condense and descend. During the condensation and descent process, high-purity nitrogen rises and leaves from the nitrogen outlet for collection; a portion of liquid nitrogen and a very small amount of impurity gases are condensed and descend. The temperature at the bottom and the middle of the distillation column are different, which allows high-purity liquid nitrogen to be separated, while the volume of impurity gases remains at the bottom of the distillation column.

[0019] Furthermore, the outlet at the bottom of the distillation column is connected to a heat exchange gas header. After exchanging heat with heat exchange components one and two, the gas is connected via a pipeline to the molecular sieve regeneration gas inlet. The top of the distillation column has a purge gas outlet, which is connected to the molecular sieve regeneration gas inlet. This portion of gas can be used for the regeneration of the molecular sieves installed inside the molecular sieve adsorption column.

[0020] Furthermore, two or more molecular sieve desorption towers are connected in parallel. Since the molecular sieve needs to be regenerated after reaching adsorption saturation, the desorption towers are partially activated and partially standby, achieving an alternating adsorption-regeneration cycle. Each molecular sieve desorption tower is set with an adsorption cycle, and immediately switches to a regenerated standby adsorption tower upon reaching the end of the cycle. This improves work efficiency.

[0021] Furthermore, the upper section of the absorption tower and the regeneration tower are equipped with several packing materials, and the lower section is a cavity section. The raw material inlet is connected to the cavity section of the absorption tower; a reboiler is provided outside the cavity section of the regeneration tower.

[0022] Furthermore, pumps and valves are installed on the pipelines connecting the deacidification unit, dehydration and drying unit, nitrogen compression unit, and liquefaction distillation unit. To achieve automated control, sensors for flow rate, temperature, and pressure detection can also be installed on the pipelines. Attached Figure Description

[0023] Figure 1 This is a flowchart of the workflow of the present invention.

[0024] Figure 2 This is a schematic diagram of a partial structure of a distillation column.

[0025] In the diagram, 1 is the absorption tower, 2 is the top liquid separator, 3 is the lean liquid cooler, 4 is the lean and rich liquid heat exchanger, 5 is the regeneration tower, 6 is the reboiler, 7 is the condenser I, 8 is the top reflux tank, 9 is the molecular sieve desorption tower, 10 is the nitrogen compressor, 11 is the turbine, 12 is the condenser II, 13 is the heat exchange gas header, 1301 is the heat exchange assembly I, 1302 is the heat exchange assembly II, 14 is the distillation tower, 1401 is the packing layer, 1402 is the cryogenic heat exchanger, 1403 is the baffle, 1404 is the bottom plate, 1405 is the longitudinal baffle, 1406 is the upper baffle, 1407 is the lower baffle, 1408 is the nitrogen inlet, 1409 is the nitrogen outlet, 1410 is the liquid nitrogen outlet, 1411 is the vent gas outlet, 1412 is the discharge outlet; A is the deacidification unit, B is the dehydration and drying unit, C is the nitrogen compression unit, and D is the liquefaction distillation unit. Detailed Implementation

[0026] like Figure 1-2 The diagram shows a nitrogen production unit for continuous oxidation of pseudotrimethylbenzene tail gas, comprising a deacidification unit A, a dehydration and drying unit B, a nitrogen compression unit C, and a liquefaction distillation unit D. The specific structure is as follows:

[0027] Deacidification Unit A: includes absorption tower 1 and regeneration tower 5; the lower part of absorption tower 1 is provided with a raw material inlet, which is connected to the tail gas outlet of the continuous oxidation reaction unit of pseudotrimethylbenzene; the top of absorption tower 1 is connected to dehydration and drying unit B after passing through the top liquid separator 2; the bottom outlet of absorption tower 1 is connected to the tube-side inlet of lean-rich liquid heat exchanger 4 (shell-tube heat exchanger); the tube-side outlet of lean-rich liquid heat exchanger 4 is connected to the middle and upper inlet of regeneration tower 5; the top of regeneration tower 5 is connected to the top reflux tank 8 through condenser 7; the reflux port at the bottom of the top reflux tank 8 is connected to the upper part of regeneration tower 5 through a reflux pipe; the top of the top reflux tank 8 is provided with a gas outlet; the bottom outlet of regeneration tower 5 is connected to the shell-side inlet of lean-rich liquid heat exchanger 4; the shell-side outlet of lean-rich liquid heat exchanger 4 is connected to the upper part of absorption tower 1 after passing through lean liquid cooler 3.

[0028] Dehydration and drying unit B: includes molecular sieve desorption tower 9, the bottom inlet of molecular sieve desorption tower 9 is connected to the top outlet of top separator 2;

[0029] Nitrogen compression unit C: includes a turbine 11 and a nitrogen compressor 10. The turbine 11 is driven to the nitrogen compressor 10, and the outlet of the nitrogen compressor 10 is connected to the inlet of the condenser 12.

[0030] Liquefaction distillation unit D includes a heat exchange gas header 13 and a distillation column 14. The heat exchange gas header 13 is equipped with heat exchange component one 1301 and heat exchange component two 1302. Heat exchange component one 1301 and heat exchange component two 1302 can be plate heat exchangers or coiled tube heat exchangers. The inlet of heat exchange component one 1301 is connected to the top outlet of the molecular sieve desorption column 9, and the outlet of heat exchange component one 1301 is connected to the inlet of the nitrogen compressor 10. The inlet of heat exchange component two 1302 is connected to the outlet of condenser two 12, and the outlet of heat exchange component two 1302 is connected to the nitrogen inlet 1408 of the distillation column 14. The upper part of the distillation column 14 is equipped with a nitrogen outlet 1409, and the middle and lower part is equipped with a liquid nitrogen outlet 1410.

[0031] The distillation column 14 comprises a vertically arranged three-section column: an upper column, a middle column, and a lower column. The diameter of the middle column is larger than that of the upper and lower columns. The upper column contains several packing layers 1401. A nitrogen inlet 1408 is located in the middle of the packing layer 1401, and a nitrogen outlet 1409 is located above the packing layer 1401. The middle column contains at least two condensation heat exchange layers, each including a bottom plate 1404, a baffle plate 1403, and a cryogenic heat exchanger 1402. The baffle plate 1403 is cylindrical and located above the bottom plate 1404, while the cryogenic heat exchanger 1402 is located within the space enclosed by the baffle plate 1403. Inside, the bottom plate 1404 on the outer side of the partition 1403 is provided with several micro-holes penetrating the bottom plate 1404; the lower tower is provided with several layers of baffle assembly, the baffle assembly includes a horizontally arranged upper baffle 1406 and lower baffle 1407, the upper baffle 1406 extends above the lower baffle 1407, a longitudinal baffle 1405 is provided on the lower baffle 1407, a liquid nitrogen pool for containing liquid nitrogen is formed between the longitudinal baffle 1405, the lower baffle 1407 and the inner wall of the tower, an overflow channel is formed between the longitudinal baffle 1405 and the upper baffle 1406, and the liquid nitrogen outlet 1410 is connected to one of the liquid nitrogen pools in the middle of the lower tower. In this scheme, liquid nitrogen is in a vapor-liquid mixed state in the packing layer 1401, and it continuously vaporizes and condenses, causing some impurity gases to condense and descend. During the condensation and descent process, high-purity nitrogen rises and leaves from the nitrogen outlet 1409 for collection; a portion of liquid nitrogen and a very small amount of impurity gases are condensed and descend. The temperature at the bottom and the middle of the distillation column 14 is different, so high-purity liquid nitrogen can be separated, and the volume of impurity gases is located at the bottom of the distillation column 14.

[0032] The outlet 1412 at the bottom of the distillation column 14 is connected to the heat exchange gas header 13. After exchanging heat with heat exchange components 1301 and 1302, the gas is connected to the molecular sieve regeneration gas inlet via a pipeline. The top of the distillation column 14 has a purge gas outlet 1411, which is connected to the molecular sieve regeneration gas inlet. The gas discharged from the purge gas outlet 1411 and the gas discharged from the bottom outlet 1412 of the distillation column 14 are used for the regeneration of the molecular sieve installed in the molecular sieve adsorption column after heat exchange.

[0033] Two molecular sieve desorption towers 9 are connected in parallel, or more. Since the molecular sieve needs regeneration after reaching adsorption saturation, the molecular sieve desorption towers 9 achieve an alternating adsorption-regeneration cycle by partially opening and partially keeping them on standby. Each molecular sieve desorption tower 9 is set with an adsorption cycle, and immediately switches to a regenerated standby adsorption tower upon reaching the end of the cycle. This improves working efficiency.

[0034] The upper section of the corresponding tower body of the absorption tower 1 and the regeneration tower 5 is equipped with several packing materials, and the lower section is a cavity section. The raw material inlet is connected to the cavity section of the absorption tower 1; the cavity section of the regeneration tower 5 is equipped with a reboiler 6.

[0035] Multiple pumps and valves can be installed on the pipelines connecting the deacidification unit A, dehydration and drying unit B, nitrogen compression unit C, and liquefaction distillation unit D to facilitate gas-liquid transport. For automated control, sensors for flow rate, temperature, and pressure detection can also be installed on the pipelines.

[0036] During operation, the nitrogen-rich tail gas from the continuous oxidation of pseudotrimethylbenzene by air first enters the absorption tower 1. The nitrogen volume content of this tail gas is above 92%, and the oxygen volume content is below 0.5%. At the same time, the tail gas contains a small amount of CO2, H2O, acetic acid, xylene, and other organic gases. CO2 has a corrosive effect on equipment and pipelines, and because of its high boiling point, it is easy to precipitate as a solid during the cooling process, so it is removed first. The tail gas enters from the bottom of the absorption tower 1 and passes through the absorption tower 1 from bottom to top. The complex amine solution (lean solution) in the absorption tower 1 enters from the top of the absorption tower 1 and passes through the absorption tower 1 from top to bottom. The counter-flowing complex amine solution and the raw material gas come into full contact in the absorption tower 1. The CO2 in the raw material gas is absorbed and enters the liquid phase. The unabsorbed components are drawn out from the top of the absorption tower 1 and enter the top liquid separator 2, where the temperature is reduced to below 40°C and then enters the dehydration and drying unit B.

[0037] The composite amine solution after CO2 absorption is called rich solution. After exiting the bottom of absorption tower 1, it exchanges heat with the solution (lean solution) flowing out from the bottom of regeneration tower 5 in the rich-lean-lean solution heat exchanger 4, and is heated to 90-98℃ before entering regeneration tower 5. In regeneration tower 5, stripping regeneration is carried out until the rich solution is regenerated into lean solution. The lean solution exiting regeneration tower 5 is cooled to 45-65℃ through the rich-lean-lean solution heat exchanger 4 and lean solution cooler 3, and then enters from the top of absorption tower 1 to complete the amine solution circulation.

[0038] Acidic gas exits from the top outlet of regeneration tower 5, and after cooling, it enters the top reflux tank 8. The acidic gas is vented from the top, and the condensate is refluxed back to regeneration tower 5, where CO2 and acetic acid are removed.

[0039] In dehydration and drying unit B, impurities such as moisture, trace amounts of CO2, and xylene in the gas are thoroughly removed by the molecular sieve desorption tower 9. The molecular sieve is the core working component of the molecular sieve desorption tower 9. After the molecular sieve reaches adsorption saturation, it needs to be regenerated. Regeneration gas is introduced through the molecular sieve regeneration gas inlet, and the molecular sieve is regenerated through temperature and pressure changes or reverse adsorption by a heater. The molecular sieve desorption tower 9 operates in a "one on, one standby" mode, achieving an alternating adsorption-regeneration cycle.

[0040] After dehydration and drying, the nitrogen gas first passes through the heat exchange component 1301 to lower its temperature, and then enters the nitrogen compressor 10 for compression. After compression, it is condensed to form a low-temperature nitrogen gas or vapor-liquid mixture, which then enters the liquefaction distillation unit D.

[0041] In the liquefaction distillation unit D, nitrogen gas is repeatedly vaporized and condensed. Trace amounts of non-condensable gases collect at the top and exit from the purge gas outlet 1411. High-concentration nitrogen gas exits from the nitrogen outlet 1409. Liquid nitrogen descends step by step, passing through the packing layer 1401 and being further cooled by the cryogenic heat exchanger 1402 in the middle column. It then overflows downwards over the baffle 1403 and enters the lower column. In the lower column, it gradually overflows downwards. During this process, impurities in the liquid nitrogen, due to their higher boiling point than nitrogen gas, gradually accumulate at the bottom of the column. This liquid nitrogen can then be used as molecular sieve regeneration gas. High-purity liquid nitrogen is discharged from the liquid nitrogen outlet 1410. The liquid nitrogen is stored in a liquid nitrogen storage tank, and the nitrogen gas is sent to the pipeline network. The purge gas is used as molecular sieve regeneration gas.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] 1. Pseudotrimethylbenzene consumes oxygen during continuous oxidation by introducing air, and at the same time, it purifies nitrogen. Further purification of nitrogen can result in higher purity of the finished product, with liquid nitrogen purity ≥99.995% and nitrogen purity as high as 99.999%.

[0044] 2. Lower energy consumption: Conventional electric air separation and liquid air separation processes average approximately 600 kW / h per ton of product. Utilizing the nitrogen-rich tail gas from this project to produce air separation products is more energy-efficient than conventional all-electric air separation, achieving approximately 430 kW / h per ton of product, representing a 30% energy saving. This demonstrates significant energy efficiency and effective resource utilization.

[0045] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A device for producing nitrogen from a continuous oxidation off-gas of a meta- xylene, characterized in that it comprises: It includes a deacidification unit, a dehydration and drying unit, a nitrogen compression unit, and a liquefaction distillation unit; among which, The deacidification unit includes an absorption tower and a regeneration tower. The lower part of the absorption tower has a raw material inlet connected to the tail gas outlet of the continuous oxidation reactor for p-xylene. The top of the absorption tower is connected to the dehydration and drying unit via a top separator. The bottom outlet of the absorption tower is connected to the tube-side inlet of a lean-rich liquid heat exchanger. The tube-side outlet of the lean-rich liquid heat exchanger is connected to the upper-middle inlet of the regeneration tower. The top of the regeneration tower is connected to a top reflux tank via a condenser. The reflux port at the bottom of the top reflux tank is connected to the upper part of the regeneration tower via a reflux pipe. The top of the top reflux tank has a gas outlet. The bottom outlet of the regeneration tower is connected to the shell-side inlet of the lean-rich liquid heat exchanger. The shell-side outlet of the lean-rich liquid heat exchanger is connected to the upper part of the absorption tower via a lean liquid cooler. Dehydration and drying unit: includes a molecular sieve desorption tower, the bottom inlet of which is connected to the top outlet of the top separator. Nitrogen compression unit: includes a turbine and a nitrogen compressor. The turbine is driven to the nitrogen compressor, and the outlet of the nitrogen compressor is connected to the inlet of condenser two. The liquefied distillation unit includes a heat exchange gas header and a distillation column. The heat exchange gas header is equipped with heat exchange component one and heat exchange component two. The inlet of heat exchange component one is connected to the top outlet of the molecular sieve desorption column, and the outlet of heat exchange component one is connected to the inlet of the nitrogen compressor. The inlet of heat exchange component two is connected to the outlet of condenser two, and the outlet of heat exchange component two is connected to the nitrogen inlet of the distillation column. The upper part of the distillation column is equipped with a nitrogen outlet, and the middle and lower parts are equipped with a liquid nitrogen outlet. The distillation column comprises a vertically arranged three-section column: an upper column, a middle column, and a lower column. The diameter of the middle column is larger than that of the upper and lower columns. The upper column contains several packing layers, with a nitrogen inlet located in the middle of the packing layers and a nitrogen outlet located above the packing layers. The middle column contains at least two condensation heat exchange layers, each including a bottom plate, a baffle plate, and a cryogenic heat exchanger. The baffle plate is cylindrical and located on the upper side of the bottom plate, while the cryogenic heat exchanger is located within the space enclosed by the baffle plate. The bottom plate outside the baffle plate has several micropores penetrating the bottom plate. The lower column contains several layers of baffle assemblies, each including a horizontally arranged upper baffle and a lower baffle plate. The upper baffle plate extends above the lower baffle plate, and a longitudinal baffle plate is located on the lower baffle plate. A liquid nitrogen pool is formed between the longitudinal baffle plate, the lower baffle plate, and the inner wall of the column to contain liquid nitrogen. An overflow channel is formed between the longitudinal baffle plate and the upper baffle plate. The liquid nitrogen outlet is connected to one of the liquid nitrogen pools in the middle of the lower column.

2. The apparatus for producing nitrogen from the continuous oxidation tail gas of pseudocumene according to claim 1, characterized in that: The outlet at the bottom of the distillation column is connected to the heat exchange gas header. After exchanging heat with heat exchange component one and heat exchange component two, it is connected to the molecular sieve regeneration gas inlet via a pipeline.

3. The apparatus for producing nitrogen from the continuous oxidation tail gas of pseudocumene according to claim 1 or 2, characterized in that: The distillation column is provided with a purge gas outlet at the top, which is connected to the molecular sieve regeneration gas inlet.

4. The apparatus for producing nitrogen from the continuous oxidation tail gas of pseudocumene according to claim 1 or 2, characterized in that: Two or more molecular sieve desorption towers are connected in parallel.

5. A continuous oxidation tail gas nitrogen production apparatus for pseudotrimethylbenzene according to claim 1 or 2, characterized in that: The upper section of the absorption tower and the regeneration tower are equipped with several packing materials, and the lower section is a cavity section. The raw material inlet is connected to the cavity section of the absorption tower; a reboiler is provided outside the cavity section of the regeneration tower.

6. A nitrogen production apparatus for continuous oxidation of tail gas of parabens according to claim 1 or 2, characterized in that: Pumps and valves are installed on the pipelines connecting the deacidification unit, dehydration and drying unit, nitrogen compression unit and liquefaction distillation unit.

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