Purified nitrogen preheating limit recovery system and method based on PSA separation nitrogen production

Abstract

The invention belongs to the technical field of nitrogen preparation, and particularly relates to a purified nitrogen preheating limit recovery system and method based on PSA separation nitrogen preparation. Comprising a nitrogen buffer tank, a gas inlet of the nitrogen buffer tank is communicated with a PSA separation nitrogen-making mechanism, a gas outlet of the nitrogen buffer tank is communicated with a dust filter, the dust filter is communicated with a reaction purification mechanism through a direct connection pipeline, the reaction purification mechanism is communicated with a drying mechanism, and the drying mechanism is communicated with the lower end of the nitrogen tank. The upper end of the nitrogen tank is communicated with the precision filter. According to the invention, nitrogen is preheated by heat generated after catalytic reaction in the reactor, energy consumption is saved, the outlet temperature of finished product nitrogen after efficient heat exchange basically reaches room temperature, cooling by cooling water is not needed, and the use amount of cooling water and the equipment cost are saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nitrogen preparation, and in particular relates to a system and method for preheating extreme recovery of purified nitrogen based on PSA separation and nitrogen preparation. Background Art

[0002] For sintering production lines such as positive electrodes such as lithium iron phosphate and lithium iron manganese phosphate, as well as carbonization of negative electrode powders, nitrogen with a purity of more than 99.99% is required as a protective gas in the sintering kiln to ensure that the sintering reaction is completed in an oxygen-free environment. At present, liquid nitrogen is usually supplied after being gasified. Due to the high price of liquid nitrogen and liquid nitrogen transportation, the process cost is also relatively high. The existing PSA nitrogen production technology uses a nitrogen generator to produce nitrogen by adsorption from the air on site, which can avoid the high cost of liquid nitrogen and the high sintering cost.

[0003] The Chinese patent application number 202010223262.X discloses a process flow of a PSA nitrogen production system, comprising two adsorption towers A and B arranged in parallel, wherein the adsorption towers A and B are connected to an intake manifold through an intake branch pipe A and an intake branch pipe B, respectively, an air inlet is arranged at one end of the intake manifold, an A tower intake valve and a B tower intake valve are arranged on the intake branch pipe A and the intake branch pipe B, respectively, and the adsorption towers A and B are respectively It is connected to the gas outlet main pipe through the gas outlet branch pipe A and the gas outlet branch pipe B, one end of the gas outlet main pipe is connected to the nitrogen buffer tank, the gas outlet valve of tower A and the gas outlet valve of tower B are respectively arranged on the gas outlet branch pipe A and the gas outlet branch pipe B, the adsorption tower A and the adsorption tower B are both connected to the upper equalizing valve and are respectively connected to the middle and lower equalizing valve of tower A and the middle and lower equalizing valve of tower B, the adsorption tower A and the adsorption tower B are respectively connected to the vent valve of tower A and the vent valve of tower B, which can improve the nitrogen production efficiency and reduce energy consumption.

[0004] However, if only one-stage PSA is used to produce nitrogen, its purity often cannot reach 99.99%, and a purification device is usually required. Most of the purification devices currently used on the market install electric heating pipes in the reaction tower filled with catalysts to provide the temperature required for the deoxygenation reaction. Since the deoxygenation reaction itself generates a lot of heat, the remaining heat is cooled by a cooling tower, which consumes both water and energy. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a system and method for preheating extreme recovery of purified nitrogen based on PSA separation and nitrogen production. The present invention realizes preheating of nitrogen by heat generated after catalytic reaction in the reactor, saving energy consumption. At the same time, the outlet temperature of the finished nitrogen after efficient heat exchange basically reaches room temperature, and no cooling water cooling is required, thereby saving cooling water consumption and equipment costs.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A purified nitrogen preheating limit recovery system based on PSA separation nitrogen production comprises a nitrogen buffer tank, an air inlet of the nitrogen buffer tank is connected to a PSA separation nitrogen production mechanism, an air outlet of the nitrogen buffer tank is connected to a dust filter, the dust filter is connected to a reaction purification mechanism through a direct pipeline, the reaction purification mechanism is connected to a drying mechanism, the drying mechanism is connected to the lower end of the nitrogen tank, and the upper end of the nitrogen tank is connected to a precision filter.

[0007] Further, the PSA separation nitrogen production mechanism includes an A adsorption tower and a B adsorption tower, the bottom of the A adsorption tower is connected to a first air inlet branch pipe, and the top of the A adsorption tower is connected to a first air outlet branch pipe; the bottom of the B adsorption tower is connected to a second air inlet branch pipe, and the top of the B adsorption tower is connected to a second air outlet branch pipe; the first air inlet branch pipe and the second air inlet branch pipe are connected to a first air inlet main pipe, the first air outlet branch pipe and the second air outlet branch pipe are connected to a first air outlet main pipe, and the first air outlet main pipe is connected to an air inlet of a nitrogen buffer tank; Valves are installed on the first air inlet branch pipe, the second air inlet branch pipe, the first air outlet branch pipe and the second air outlet branch pipe.

[0008] Furthermore, the first air intake branch pipe and the second air intake branch pipe are connected by a pipeline, the connecting point of the pipeline is located between the valve of the corresponding adsorption tower and the air intake branch pipe, and two first exhaust valves are installed on the pipeline, and a first exhaust port is provided on the pipeline between the two first exhaust valves; The first outlet branch pipe is connected to the second outlet branch pipe through a pipeline, the connecting point of the pipeline is located between the valve of the corresponding adsorption tower and the outlet branch pipe, and a first reflux valve is installed on the pipeline.

[0009] Furthermore, the interiors of the A adsorption tower and the B adsorption tower are filled with an adsorbent, and the adsorbent is a carbon molecular sieve.

[0010] Furthermore, the reaction purification mechanism includes an A reactor and a B reactor, the dust filter is connected to one end of the A three-way reversing valve, and the other two ends of the A three-way reversing valve are respectively connected to the bottom of the A reactor and the bottom of the B reactor through pipelines; the top of the A reactor and the top of the B reactor are respectively connected to the two ends of the heater, and a B three-way reversing valve is also provided under the B reactor; the two ends of the B three-way reversing valve are respectively connected to the bottom of the A reactor and the bottom of the B reactor, and the third end of the B three-way reversing valve is connected to the drying mechanism.

[0011] Furthermore, the interiors of the A reactor and the B reactor are both filled with carbon-supported catalysts, and the carbon-supported catalysts are honeycomb structures.

[0012] Further, the drying mechanism includes an A drying tower and a B drying tower, the bottom of the A drying tower is connected to a first drying air inlet pipe, and the top of the A drying tower is connected to a first drying air outlet pipe; the bottom of the B drying tower is connected to a second drying air inlet pipe, and the top of the B drying tower is connected to a second drying air outlet pipe; the first drying air inlet pipe and the second drying air inlet pipe are connected to the second air inlet main pipe, and the first drying air outlet pipe and the second drying air outlet pipe are connected to the second air outlet main pipe; the second air inlet main pipe is connected to the third end of the B three-way reversing valve 16, and the second air outlet main pipe is connected to the lower end of the nitrogen tank; Valves are installed on the first drying air inlet pipe, the second drying air inlet pipe, the first drying air outlet pipe, the second drying air outlet pipe and the second air outlet main pipe.

[0013] Furthermore, the first drying air inlet pipe and the second drying air inlet pipe are connected by a pipeline, the connecting point of the pipeline is located between the valves of the corresponding drying tower and the drying air inlet pipe, and two second exhaust valves are installed on the pipeline, and a second exhaust port is provided on the pipeline between the two second exhaust valves; The first drying outlet pipe and the second drying outlet pipe are both connected to the second outlet pipe through an independent pipe, one end of the independent pipe is connected between the valve of the corresponding drying tower and the drying outlet pipe, and the other end of the independent pipe is connected between the valve of the second outlet pipe and the nitrogen tank; a one-way valve is installed on each independent pipe, and the flow direction of the one-way valve is to flow to the corresponding drying tower side; The valves on the first drying air outlet pipe and the second drying air outlet pipe are both one-way valves, and the flow direction of the one-way valve is to flow to the side of the second air outlet pipe.

[0014] Furthermore, the air inlet of the PSA separation nitrogen production mechanism is connected to the lower end of the air tank, the upper end of the air tank is connected in series with a class A filter and a class T filter in sequence, one end of the class T filter is connected to a cold dryer, and one end of the cold dryer is connected in series with a class C filter, an air buffer tank and an air compressor in sequence.

[0015] The present invention also claims a method for producing nitrogen using the above-mentioned purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production, comprising the following steps: S1. The air is compressed by the air compressor and stored in the air buffer tank. After that, it is filtered by the C-level filter and enters the cold dryer to remove most of the moisture in the compressed air. Then, it passes through the T-level filter and the A-level filter to obtain clean compressed air, which is stored in the air tank. The clean compressed air is adsorbed in the A adsorption tower to remove oxygen, and then the pure nitrogen with a purity of 99.9% is obtained and stored in the nitrogen buffer tank. S2. When the carbon molecular sieve in adsorption tower A is saturated with adsorbed oxygen, the adsorption step is stopped and adsorption is switched to adsorption tower B; while in adsorption tower A, its pressure is reduced, and it is purged with general nitrogen to release oxygen and empty it, thereby achieving regeneration; the two alternately adsorb and regenerate to ensure the continuous output of general nitrogen; S3, after the ordinary nitrogen in the nitrogen buffer tank passes through the dust filter, it enters the A three-way reversing valve from the bottom of the A reactor, flows out from the top of the A reactor, passes through the heater, and the gas temperature is raised to 300°C after the ordinary nitrogen passes through the heater, and then enters from the top of the B reactor. The honeycomb carbon-supported catalyst filled inside the B reactor, carbon and oxygen react under the catalyst to release a large amount of heat, most of which is stored in the honeycomb body, and then the nitrogen flows out from the bottom of the B reactor, and enters the drying tower through the B three-way reversing valve for drying and adsorption. The A drying tower and the B drying tower work alternately, and the nitrogen is finally stored in the nitrogen tank. After passing through the last precision filter, high-purity nitrogen with a purity of 99.999% can be obtained; S4. By adjusting the A three-way reversing valve and the B three-way reversing valve to switch the direction, the general nitrogen from the dust filter enters from the bottom of the B reactor. Due to the high temperature inside the B reactor before switching, the general nitrogen is preheated. After flowing out from the top of the B reactor, the general nitrogen reaches 300°C in conjunction with the heater and flows into the top of the A reactor. The oxygen in it directly reacts with the carbon through catalysis and releases a large amount of heat, which is stored in the honeycomb body. After that, the purified nitrogen flows out from the bottom of the A reactor and enters the drying tower for drying through the B three-way reversing valve. After this step, the switching cycle is carried out to fully recycle the waste heat.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, compressed air of sufficient pressure enters a pressure swing adsorption device composed of two adsorption towers filled with carbon molecular sieves. The compressed air flows through the adsorption tower from bottom to top, during which oxygen molecules are adsorbed on the surface of the carbon molecular sieve, and nitrogen flows out from the upper end of the adsorption tower and enters the nitrogen buffer tank. After a period of time, the carbon molecular sieve in the adsorption tower is saturated with adsorbed oxygen and needs to be regenerated. Regeneration is achieved by stopping the adsorption step and reducing the pressure of the adsorption tower. The two adsorption towers alternately perform adsorption and regeneration to ensure continuous output of nitrogen. The purity of nitrogen in the nitrogen buffer tank can basically reach 99.9%, providing purification conditions for subsequent purification by the carbon-supported purification device.

[0017] (2) The present invention adopts the parallel structural design of the A reactor and the B reactor and cooperates with the heater, so that after the linkage switching of the A three-way reversing valve and the B three-way reversing valve, the general nitrogen can be preheated by one reactor first to absorb the heat stored in the honeycomb body of the reactor, and then enter the other reactor for catalytic reaction, and the switching cycle is continuously carried out. Through the different actions of the two reactors in sequence, the heat generated after the catalytic reaction in the reactor is used to preheat the nitrogen, saving energy consumption. At the same time, the outlet temperature of the finished nitrogen after efficient heat exchange basically reaches room temperature, and no cooling water cooling is required, saving cooling water consumption and equipment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the overall structure of a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production according to the present invention; Figure 2 A schematic diagram of the structure of a PSA separation nitrogen production mechanism of a purified nitrogen preheating limit recovery system based on PSA separation nitrogen production of the present invention; Figure 3 It is a partial structural schematic diagram of a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production of the present invention; Figure 4 The present invention is a schematic diagram of the drying mechanism structure of a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production.

[0019] The reference numerals are as follows: 1-air compressor; 2-air buffer tank; 3-C-level filter; 4-cold dryer; 5-T-level filter; 6-A-level filter; 7-air tank; 8-A adsorption tower; 9-B adsorption tower; 10-nitrogen buffer tank; 11-dust filter; 12-A three-way reversing valve; 13-A reactor; 14-heater; 15-B reactor; 16-B three-way reversing valve; 17-A drying tower; 18-B drying tower; 19-nitrogen tank; 20-precision filter; 110-first air intake main pipe; 120-first air intake branch pipe; 130-second air intake branch pipe; 140-first air outlet branch pipe; 150-second air outlet branch pipe; 160-first air outlet main pipe; 210-second air intake main pipe; 220-first dry air intake pipe; 230-second dry air intake pipe; 240-first dry air outlet pipe; 250-second dry air outlet pipe; 260-second air outlet main pipe. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0021] Although the steps in the present invention are arranged with numbers, they are not used to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" used in this article involves and covers any and all possible combinations of one or more of the associated listed items.

[0022] Example

[0023] like Figure 1~Figure 4 As shown, a purified nitrogen preheating limit recovery system based on PSA separation nitrogen production includes a nitrogen buffer tank 10, the air inlet of the nitrogen buffer tank 10 is connected to the PSA separation nitrogen production mechanism, the air outlet of the nitrogen buffer tank 10 is connected to the dust filter 11, the dust filter 11 is connected to the reaction purification mechanism through a direct pipeline, the reaction purification mechanism is connected to the drying mechanism, the drying mechanism is connected to the lower end of the nitrogen tank 19, and the upper end of the nitrogen tank 19 is connected to the precision filter 20.

[0024] It is worth mentioning that the PSA separation nitrogen production mechanism is used to separate general nitrogen, and the reaction purification mechanism is used for reaction purification, which will be explained in detail later.

[0025] Further, the PSA separation nitrogen production mechanism includes an A adsorption tower 8 and a B adsorption tower 9, the bottom of the A adsorption tower 8 is connected to a first air inlet branch pipe 120, and the top of the A adsorption tower 8 is connected to a first air outlet branch pipe 140; the bottom of the B adsorption tower 9 is connected to a second air inlet branch pipe 130, and the top of the B adsorption tower 9 is connected to a second air outlet branch pipe 150; the first air inlet branch pipe 120 and the second air inlet branch pipe 130 are connected to the first air inlet main pipe 110, the first air outlet branch pipe 140 and the second air outlet branch pipe 150 are connected to the first air outlet main pipe 160, and the first air outlet main pipe 160 is connected to the air inlet of the nitrogen buffer tank 10; The first air inlet branch pipe 120 , the second air inlet branch pipe 130 , the first air outlet branch pipe 140 and the second air outlet branch pipe 150 are all equipped with valves for controlling the flow direction of nitrogen.

[0026] Furthermore, the first intake branch pipe 120 and the second intake branch pipe 130 are connected by a pipeline, the connecting point of the pipeline is located between the valve of the corresponding adsorption tower and the intake branch pipe, and two first exhaust valves are installed on the pipeline, and a first exhaust port is provided on the pipeline between the two first exhaust valves; The first outlet branch pipe 140 and the second outlet branch pipe 150 are connected via a pipeline, the connecting point of the pipeline is located between the valve of the corresponding adsorption tower and the outlet branch pipe, and a first reflux valve is installed on the pipeline.

[0027] The compressed air that meets the pressure enters a pressure swing adsorption device composed of two adsorption towers filled with carbon molecular sieves. The compressed air flows through the adsorption tower from bottom to top, during which the oxygen molecules are adsorbed on the surface of the carbon molecular sieve, and the nitrogen flows out from the upper end of the adsorption tower and enters the nitrogen buffer tank 10. After a period of time, the carbon molecular sieve in the adsorption tower is saturated with adsorbed oxygen and needs to be regenerated. Regeneration is achieved by stopping the adsorption step and reducing the pressure of the adsorption tower. The two adsorption towers alternately perform adsorption and regeneration to ensure the continuous output of nitrogen. The purity of nitrogen in the nitrogen buffer tank can basically reach 99.9%, providing purification conditions for subsequent purification by the carbon-loaded purification device.

[0028] Specifically, when adsorption tower A 8 is required and adsorption tower B 9 is required to be regenerated, the valves on the first air inlet branch 120 and the first air outlet branch 140 are opened, the valves on the second air inlet branch 130 and the second air outlet branch 150 are closed, and the first reflux valve and one of the first exhaust valves are opened, so that while adsorption tower A 8 is adsorbing, nitrogen can flow back into adsorption tower B 9 from the first reflux valve and be discharged from the first exhaust port, thereby regenerating adsorption tower B 9; when regeneration of adsorption tower A 8 and adsorption of adsorption tower B 9 are required, the reverse operation can be performed.

[0029] Furthermore, a valve structure is also installed on the first gas outlet main pipe 160, so as to more conveniently adjust the nitrogen flow direction.

[0030] Furthermore, the interiors of the A adsorption tower 8 and the B adsorption tower 9 are filled with an adsorbent, which is a carbon molecular sieve. The carbon molecular sieve adsorbs oxygen, carbon dioxide, water, etc. in the air, but cannot adsorb nitrogen.

[0031] The diffusion rates of oxygen and nitrogen gas molecules on the molecular sieve surface are different. The diffusion rate of O2 gas molecules with smaller diameter is faster and more of them enter the micropores of carbon molecular sieve. The diffusion rate of N2 gas molecules with larger diameter is slower and less of them enter the micropores of carbon molecular sieve. By taking advantage of the difference in the selective adsorption of nitrogen and oxygen by carbon molecular sieve, oxygen is enriched in the adsorption phase and nitrogen is enriched in the gas phase in a short time. In this way, oxygen and nitrogen are separated and nitrogen is enriched in the gas phase under PSA conditions.

[0032] Furthermore, the reaction purification mechanism includes an A reactor 13 and a B reactor 15, the dust filter 11 is connected to one end of the A three-way reversing valve 12, and the other two ends of the A three-way reversing valve 12 are respectively connected to the bottom of the A reactor 13 and the bottom of the B reactor 15 through pipelines; the top of the A reactor 13 and the top of the B reactor 15 are respectively connected to the two ends of the heater 14, and a B three-way reversing valve 16 is also provided below the B reactor 15; the two ends of the B three-way reversing valve 16 are respectively connected to the bottom of the A reactor 13 and the bottom of the B reactor 15, and the third end of the B three-way reversing valve 16 is connected to the drying mechanism.

[0033] Furthermore, the interiors of the A reactor 13 and the B reactor 15 are filled with carbon-supported catalysts, and the carbon-supported catalysts are honeycomb-shaped. The honeycomb-shaped carbon-supported catalysts have strong heat storage and high heat exchange efficiency.

[0034] The present invention adopts the parallel structural design of the A reactor 13 and the B reactor 15 and cooperates with the heater 14, so that after the linkage switching of the A three-way reversing valve 12 and the B three-way reversing valve 16, the general nitrogen can be preheated by one reactor first to absorb the heat stored in the honeycomb body in the reactor, and then enter the other reactor for catalytic reaction, and the switching cycle is continuously carried out. Through the different functions of the two reactors, the heat generated after the catalytic reaction in the reactor is used to preheat the nitrogen, saving energy consumption. At the same time, the outlet temperature of the finished nitrogen after efficient heat exchange basically reaches room temperature, and no cooling water cooling is required, thereby saving cooling water consumption and equipment cost.

[0035] Specifically, after the ordinary nitrogen in the nitrogen buffer tank 10 passes through the dust filter 11, it enters from the bottom of the A reactor 13 through the A three-way reversing valve 12 and flows out from the top of the A reactor 13. Since it is the first time to enter, there is no heat storage inside the A reactor 13, and it needs to be heated by the heater 14. After the ordinary nitrogen passes through the heater 14, the gas temperature is raised to 300°C, and then it enters from the top of the B reactor 15. The honeycomb carbon-supported catalyst filled inside the B reactor 15 reacts with carbon and oxygen under the catalyst to release a large amount of heat, most of which is stored in the honeycomb body. Then the nitrogen flows out from the bottom of the B reactor 15 and enters the drying tower through the B three-way reversing valve 16 for drying and adsorption. The A drying tower 17 and the B drying tower 18 work alternately. Finally, the nitrogen is stored in the nitrogen tank 19. After passing through the last precision filter 20, 99.999% high-purity nitrogen can be obtained; A specific switching time is set, and switching is performed by adjusting the A three-way switching valve 12 and the B three-way switching valve 16. After switching, the general nitrogen of the dust filter 11 enters from the bottom of the B reactor 15. Due to the high temperature inside the B reactor 15 and the heat storage of the honeycomb body before switching, the general nitrogen is preheated. After flowing out from the top of the B reactor 15, the general nitrogen is made to reach 300°C in cooperation with the heater 14 and flows into the top of the A reactor 13. The oxygen therein directly reacts with the carbon through catalysis and releases a large amount of heat, which is stored in the honeycomb body of the A reactor 13. After that, the purified nitrogen flows out from the bottom of the A reactor 13 and enters the drying tower for drying through the B three-way switching valve 16. After this step, the switching cycle is performed to fully recycle the waste heat to the extreme. It is worth noting that after the above-mentioned reversal, due to the high temperature inside the B reactor 15 and the heat storage of the honeycomb body, the general nitrogen is preheated. After preheating, the temperature can basically meet the reaction requirements. At this time, the heater 14 can be turned off to save energy. If the temperature does not meet the requirements, it can also be appropriately heated by the heater 14 to save energy.

[0036] Further, the drying mechanism includes an A drying tower 17 and a B drying tower 18, the bottom of the A drying tower 17 is connected to a first drying air inlet pipe 220, and the top of the A drying tower 17 is connected to a first drying air outlet pipe 240; the bottom of the B drying tower 18 is connected to a second drying air inlet pipe 230, and the top of the B drying tower 18 is connected to a second drying air outlet pipe 250; the first drying air inlet pipe 220 and the second drying air inlet pipe 230 are connected to the second air inlet main pipe 210, and the first drying air outlet pipe 240 and the second drying air outlet pipe 250 are connected to the second air outlet main pipe 260; the second air inlet main pipe 210 is connected to the third end of the B three-way reversing valve 16, and the second air outlet main pipe 260 is connected to the lower end of the nitrogen tank 19; Valves are installed on the first drying air inlet pipe 220 , the second drying air inlet pipe 230 , the first drying air outlet pipe 240 , the second drying air outlet pipe 250 and the second air outlet main pipe 260 .

[0037] Furthermore, the first drying air inlet pipe 220 and the second drying air inlet pipe 230 are connected by a pipeline, the connecting point of the pipeline is located between the valves of the corresponding drying tower and the drying air inlet pipe, and two second exhaust valves are installed on the pipeline, and a second exhaust port is provided on the pipeline between the two second exhaust valves; The first drying outlet pipe 240 and the second drying outlet pipe 250 are both connected to the second outlet main pipe 260 through an independent pipe, one end of the independent pipe is connected between the valve of the corresponding drying tower and the drying outlet pipe, and the other end of the independent pipe is connected between the valve of the second outlet main pipe 260 and the nitrogen tank 19; a one-way valve is installed on each independent pipe, and the flow direction of the one-way valve is to flow to the corresponding drying tower side; The valves on the first drying air outlet pipe 240 and the second drying air outlet pipe 250 are both one-way valves, and the flow direction of the one-way valve is to flow toward the second air outlet main pipe 260 .

[0038] The drying tower A 17 and the drying tower B 18 of the present invention also work alternately, thereby ensuring that the drying towers can continue to dry.

[0039] Specifically, when the A drying tower 17 is drying and the B drying tower 18 is not working, the valves on the first drying air inlet pipe 220 and the second air outlet pipe 260 are opened, and nitrogen flows into the A drying tower 17 and flows out from the second air outlet pipe 260. The valve on the second drying air inlet pipe 230 is closed, and one of the second exhaust valves is opened at the same time, and the nitrogen flowing out of the A drying tower 17 enters the B drying tower 18 and is discharged from the second exhaust port from one of the second exhaust valves; when the A drying tower 17 is not working and the B drying tower 18 is drying, the reverse operation can be performed.

[0040] Furthermore, the air inlet of the PSA separation nitrogen production mechanism is connected to the lower end of the air tank 7, the upper end of the air tank 7 is connected in series with a class A filter 6 and a class T filter 5 in sequence, one end of the class T filter 5 is connected to a cold dryer 4, and one end of the cold dryer 4 is connected in series with a class C filter 3, an air buffer tank 2 and an air compressor 1 in sequence.

[0041] It is worth noting that the A-level filter 6, C-level filter 3, T-level filter 5, etc. of the present invention can filter different particulate matter, which is the prior art and will not be described in detail here.

[0042] A method for producing nitrogen using the above-mentioned purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production comprises the following steps: S1, air is compressed by air compressor 1 and stored in air buffer tank 2, then filtered by C-level filter 3 and enters cold dryer 4 to remove most of the water in the compressed air, and then passes through T-level filter 5 and A-level filter 6 respectively to obtain clean compressed air, which is stored in air tank 7; the clean compressed air is adsorbed in A adsorption tower 8 to remove oxygen, and then obtained general nitrogen with a purity of 99.9% is stored in nitrogen buffer tank 10; S2, when the carbon molecular sieve in the A adsorption tower 8 is saturated with adsorbed oxygen, the adsorption step is stopped and the adsorption is switched to the B adsorption tower 9; while in the A adsorption tower 8, its pressure is reduced, and it is purged with general nitrogen to release oxygen and empty it, thereby achieving regeneration; the two alternately adsorb and regenerate to ensure the continuous output of general nitrogen; S3, after the ordinary nitrogen in the nitrogen buffer tank 10 passes through the dust filter 11, it enters from the bottom of the A reactor 13 through the A three-way reversing valve 12, flows out from the top of the A reactor 13, and passes through the heater 14. After the ordinary nitrogen passes through the heater 14, the gas temperature is raised to 300°C, and then enters from the top of the B reactor 15. The honeycomb carbon-supported catalyst filled inside the B reactor 15 reacts with carbon and oxygen under the catalyst to release a large amount of heat, most of which is stored in the honeycomb body. Then, the nitrogen flows out from the bottom of the B reactor 15, enters the drying tower through the B three-way reversing valve 16 for drying and adsorption, and the A drying tower 17 and the B drying tower 18 work alternately. Finally, the nitrogen is stored in the nitrogen tank 19. After passing through the last precision filter 20, high-purity nitrogen with a purity of 99.999% can be obtained; S4, by adjusting the A three-way reversing valve 12 and the B three-way reversing valve 16 to switch, the general nitrogen of the dust filter 11 enters from the bottom of the B reactor 15. Due to the high temperature inside the B reactor 15 before switching, the general nitrogen is preheated. After flowing out from the top of the B reactor 15, the general nitrogen is made to reach 300°C in cooperation with the heater 14 and flows into the top of the A reactor 13. The oxygen therein directly reacts with the carbon through catalysis and releases a large amount of heat, which is stored in the honeycomb body; thereafter, the purified nitrogen flows out from the bottom of the A reactor 13, enters the drying tower through the B three-way reversing valve 16 for drying; after this step, the switching cycle is performed to fully recycle the waste heat; The residual oxygen in the carbon and nitrogen reacts with a catalyst at 300°C to produce carbon dioxide and a trace amount of water, and releases a large amount of heat.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A purified nitrogen preheating limit recovery system based on PSA separation nitrogen production, characterized in that: It comprises a nitrogen buffer tank (10), the air inlet of the nitrogen buffer tank (10) is connected to a PSA separation nitrogen production mechanism, the air outlet of the nitrogen buffer tank (10) is connected to a dust filter (11), the dust filter (11) is connected to a reaction purification mechanism through a direct pipeline, the reaction purification mechanism is connected to a drying mechanism, the drying mechanism is connected to the lower end of a nitrogen tank (19), and the upper end of the nitrogen tank (19) is connected to a precision filter (20); The reaction purification mechanism comprises an A reactor (13) and a B reactor (15); the dust filter (11) is connected to one end of an A three-way reversing valve (12); the other two ends of the A three-way reversing valve (12) are respectively connected to the bottom of the A reactor (13) and the bottom of the B reactor (15) through pipelines; the top of the A reactor (13) and the top of the B reactor (15) are respectively connected to the two ends of the heater (14); a B three-way reversing valve (16) is further provided below the B reactor (15); the two ends of the B three-way reversing valve (16) are respectively connected to the bottom of the A reactor (13) and the bottom of the B reactor (15); the third end of the B three-way reversing valve (16) is connected to a drying mechanism; The interiors of the A reactor (13) and the B reactor (15) are both filled with a carbon-supported catalyst, and the carbon-supported catalyst is a honeycomb structure.

2. According to claim 1, a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production is characterized in that: The PSA separation nitrogen production mechanism comprises an A adsorption tower (8) and a B adsorption tower (9); the bottom of the A adsorption tower (8) is connected to a first air inlet branch pipe (120), and the top of the A adsorption tower (8) is connected to a first air outlet branch pipe (140); the bottom of the B adsorption tower (9) is connected to a second air inlet branch pipe (130), and the top of the B adsorption tower (9) is connected to a second air outlet branch pipe (150); the first air inlet branch pipe (120) and the second air inlet branch pipe (130) are connected to a first air inlet main pipe (110), the first air outlet branch pipe (140) and the second air outlet branch pipe (150) are connected to a first air outlet main pipe (160), and the first air outlet main pipe (160) is connected to an air inlet of a nitrogen buffer tank (10); Valves are installed on the first air intake branch pipe (120), the second air intake branch pipe (130), the first air outlet branch pipe (140) and the second air outlet branch pipe (150).

3. According to claim 2, a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production is characterized in that: The first air intake branch pipe (120) and the second air intake branch pipe (130) are connected via a pipeline, the connecting point of the pipeline is located between the valves of the corresponding adsorption tower and the air intake branch pipe, and two first exhaust valves are installed on the pipeline, and a first exhaust port is provided on the pipeline between the two first exhaust valves; The first gas outlet branch pipe (140) and the second gas outlet branch pipe (150) are connected via a pipeline, the connecting point of the pipeline is located between the valve of the corresponding adsorption tower and the gas outlet branch pipe, and a first reflux valve is installed on the pipeline.

4. According to claim 2, a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production is characterized in that: The interiors of the A adsorption tower (8) and the B adsorption tower (9) are both filled with an adsorbent, and the adsorbent is a carbon molecular sieve.

5. According to the PSA separation nitrogen purification preheating limit recovery system of claim 1, it is characterized in that: The drying mechanism comprises an A drying tower (17) and a B drying tower (18); the bottom of the A drying tower (17) is connected to a first drying air inlet pipe (220), and the top of the A drying tower (17) is connected to a first drying air outlet pipe (240); the bottom of the B drying tower (18) is connected to a second drying air inlet pipe (230), and the top of the B drying tower (18) is connected to a second drying air outlet pipe (250); the first drying air inlet pipe (220) and the second drying air inlet pipe (230) are connected to a second air inlet main pipe (210), and the first drying air outlet pipe (240) and the second drying air outlet pipe (250) are connected to a second air outlet main pipe (260); the second air inlet main pipe (210) is connected to a third end of the B three-way reversing valve (16), and the second air outlet main pipe (260) is connected to a lower end of a nitrogen tank (19); Valves are installed on the first drying air inlet pipe (220), the second drying air inlet pipe (230), the first drying air outlet pipe (240), the second drying air outlet pipe (250) and the second air outlet main pipe (260).

6. According to claim 5, a purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production is characterized in that: The first drying air inlet pipe (220) and the second drying air inlet pipe (230) are connected via a pipeline, the connecting point of the pipeline is located between the valves of the corresponding drying tower and the drying air inlet pipe, and two second exhaust valves are installed on the pipeline, and a second exhaust port is provided on the pipeline between the two second exhaust valves; The first drying gas outlet pipe (240) and the second drying gas outlet pipe (250) are both connected to the second gas outlet main pipe (260) via independent pipes, one end of the independent pipe being connected between the valve of the corresponding drying tower and the drying gas outlet pipe, and the other end of the independent pipe being connected between the valve of the second gas outlet main pipe (260) and the nitrogen tank (19); a one-way valve is installed on each of the independent pipes, and the flow direction of the one-way valve is to flow toward the corresponding drying tower side; The valves on the first drying air outlet pipe (240) and the second drying air outlet pipe (250) are both one-way valves, and the flow direction of the one-way valves is to flow towards the side of the second air outlet main pipe (260).

7. The purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production according to claim 1 is characterized in that: The air inlet of the PSA separation nitrogen production mechanism is connected to the lower end of the air tank (7); the upper end of the air tank (7) is connected in series with an A-class filter (6) and a T-class filter (5); one end of the T-class filter (5) is connected in series with a cold dryer (4); and one end of the cold dryer (4) is connected in series with a C-class filter (3), an air buffer tank (2) and an air compressor (1).

8. A method for producing nitrogen using the purified nitrogen preheating limit recovery system based on PSA separation and nitrogen production according to any one of claims 1 to 7, characterized in that: The steps include: S1, air is compressed by an air compressor (1), stored in an air buffer tank (2), filtered by a C-class filter (3), and then enters a cold dryer (4) to remove most of the moisture in the compressed air. The air is then filtered by a T-class filter (5) and an A-class filter (6) to obtain clean compressed air, which is stored in an air tank (7). The clean compressed air is adsorbed in an A adsorption tower (8) to remove oxygen, and then obtained as general nitrogen with a purity of 99.9%, which is then stored in a nitrogen buffer tank (10); S2, when the carbon molecular sieve in the A adsorption tower (8) is saturated with adsorbed oxygen, the adsorption step is stopped and the adsorption is switched to the B adsorption tower (9); while in the A adsorption tower (8), the pressure is reduced and purged with normal nitrogen to release oxygen and empty the tower, thereby achieving regeneration; the two towers alternately adsorb and regenerate to ensure continuous output of normal nitrogen; S3, after the ordinary nitrogen in the nitrogen buffer tank (10) passes through the dust filter (11), it enters the A three-way reversing valve (12) from the bottom of the A reactor (13), flows out from the top of the A reactor (13), passes through the heater (14), and after the ordinary nitrogen passes through the heater (14), the gas temperature is raised to 300°C, and then enters from the top of the B reactor (15). The honeycomb carbon-supported catalyst filled inside the B reactor (15) reacts with carbon and oxygen under the catalyst to release a large amount of heat, most of which is stored in the honeycomb body. Then, the nitrogen flows out from the bottom of the B reactor (15), passes through the B three-way reversing valve (16) and enters the drying tower for drying and adsorption. The A drying tower (17) and the B drying tower (18) work alternately. Finally, the nitrogen is stored in the nitrogen tank (19). After passing through the last precision filter (20), high-purity nitrogen with a purity of 99.999% can be obtained; S4. By adjusting the A three-way reversing valve (12) and the B three-way reversing valve (16) to switch, the general nitrogen from the dust filter (11) enters from the bottom of the B reactor (15). Due to the high temperature inside the B reactor (15) before switching, the general nitrogen is preheated. After flowing out from the top of the B reactor (15), the general nitrogen is made to reach 300° C. in cooperation with the heater (14) and flows into the top of the A reactor (13). The oxygen in the nitrogen directly reacts with the carbon through catalysis and releases a large amount of heat, which is stored in the honeycomb body. After that, the purified nitrogen flows out from the bottom of the A reactor (13) and enters the drying tower for drying through the B three-way reversing valve (16). After this step, the switching cycle is performed to fully recycle the waste heat to the maximum extent.

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