A method and apparatus system for separating hydrogen and helium from synthetic ammonia tail gas
By using an alloy separation unit system, the selective adsorption of hydrogen by alloy materials solves the problem of low energy consumption in the separation of hydrogen and helium in ammonia synthesis tail gas, realizes the separation of high-purity hydrogen and helium, reduces production costs and improves environmental benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU REFINETEK CO LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies struggle to efficiently separate hydrogen and helium from ammonia synthesis tail gas with low energy consumption. Hollow fiber membrane separation and pressure swing adsorption methods result in insufficient hydrogen purity, while cryogenic separation methods are energy-intensive and unsuitable for high-concentration hydrogen.
The device system consists of alloy separation units, including primary, secondary, and tertiary alloy separation units. It achieves hydrogen-helium separation by selectively adsorbing hydrogen through alloy materials and performing adsorption and desorption with the assistance of circulating water and a chiller/heater.
With low energy consumption, the hydrogen purity was increased from 90% to 99.9999%, and high-purity helium was recovered, reducing production costs, simplifying processes, and achieving both environmental and economic benefits.
Smart Images
Figure CN122321618A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ammonia synthesis tail gas separation technology, specifically to a method and apparatus system for separating hydrogen and helium from ammonia synthesis tail gas. Background Technology
[0002] In the ammonia synthesis process, natural gas is used as a raw material, and its recycling system emits a certain amount of tail gas containing various components such as ammonia, hydrogen, helium, and methane. Recovering useful gases from this tail gas can achieve both increased production and reduced energy consumption, while also benefiting environmental protection and carbon neutrality requirements. Currently, the main methods for recovering ammonia synthesis tail gas include hollow fiber membrane separation, pressure swing adsorption (PSA), and cryogenic separation. However, these methods all have significant drawbacks. The hydrogen purity obtained by hollow fiber membrane separation and PSA cannot reach above 99%, and most importantly, they cannot recover and purify helium from the tail gas. Cryogenic separation cannot handle ammonia synthesis tail gas containing high concentrations of hydrogen. To handle high-concentration hydrogen, more pre-processing is required, and this method is energy-intensive, placing a significant burden on production costs.
[0003] Therefore, this invention provides a method and apparatus system for separating hydrogen and helium from ammonia synthesis tail gas. It can directly process a hydrogen-helium mixture containing a high concentration of hydrogen in ammonia synthesis tail gas and obtain hydrogen and helium of grade 5N or higher through different alloy separation units with low energy consumption and a simple process. This invention reduces the overall cost of ammonia synthesis and provides impetus for the country to achieve the goal of carbon neutrality. Summary of the Invention
[0004] The purpose of this invention is to provide a method and apparatus system for separating hydrogen and helium from ammonia synthesis tail gas, so as to achieve the separation of hydrogen-helium mixture containing high concentration of hydrogen from ammonia synthesis tail gas with low energy consumption.
[0005] The objective of this invention is achieved through the following technical solution:
[0006] A device system for separating hydrogen and helium from ammonia synthesis tail gas, the device system comprising a primary alloy separation unit, a secondary alloy separation unit, a tertiary alloy separation unit, a circulating water unit, a chiller / heater unit, a compressor unit, a vacuum pump unit, and low-pressure buffer tanks 1 and 2 and high-pressure buffer tanks 1 and 2, the compressor unit comprising compressor 1 and compressor 2;
[0007] The raw material gas inlet, low-pressure buffer tank 1, compressor 1, high-pressure buffer tank 1, primary alloy separation unit, filter, low-pressure buffer tank 2, compressor 2, high-pressure buffer tank 2, secondary alloy separation unit, and tertiary alloy separation unit are connected in sequence.
[0008] The primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit each include two or more sets of alloy separation columns. The alloy separation columns are either used with one standby or used with multiple standby columns. The alloy separation columns of the same level are connected in parallel. The connection between the primary alloy separation unit and the secondary alloy separation unit and the tertiary alloy separation unit is connected in series.
[0009] The primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit are all equipped with flow meters, check valves, pneumatic valves, and filters on their inlet and outlet pipes.
[0010] Each alloy separation unit is equipped with a vacuum pump;
[0011] The alloy separation column is filled with packing material, all of which are alloy materials. The alloy materials are reversibly absorbable and desorbable hydrogen, and are selected from one or more alloys selected from magnesium alloys, titanium alloys, or lanthanum-nickel alloys.
[0012] This application also claims a method for separating hydrogen and helium from ammonia synthesis tail gas, employing the aforementioned apparatus system for separating hydrogen and helium from ammonia synthesis tail gas, the method comprising the following steps:
[0013] S1. The raw material gas for ammonia synthesis is pretreated to remove impurities and moisture to obtain a hydrogen-helium mixture that enters a low-pressure buffer tank 1. The hydrogen-helium mixture exits from the low-pressure buffer tank 1 and is then compressed and pressurized by compressor 1 before entering the high-pressure buffer tank 1.
[0014] S2. The gas from the high-pressure buffer tank 1 enters the first-stage alloy separation unit. In the first-stage alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working with the assistance of circulating cold water adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state and is heated and desorbed with the assistance of circulating hot water. The hydrogen obtained by desorption reaches the purity of 6N level. After most of the hydrogen is desorbed, vacuum desorption is performed to ensure that the column is completely desorbed. After the alloy separation column has completed the desorption, it enters the standby state. The first-stage alloy separation unit separates a hydrogen-helium mixture with a hydrogen concentration of 5-15%.
[0015] S3. The hydrogen-helium mixture with a hydrogen concentration of 5-15% separated by the primary alloy separation unit is filtered and enters the low-pressure buffer tank 2. The hydrogen-helium mixture exits from the low-pressure buffer tank 2 and is then compressed and pressurized by the compressor 2 before entering the high-pressure buffer tank 2.
[0016] S4. The gas from the high-pressure buffer tank 2 enters the secondary alloy separation unit. In the secondary alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working under the assistance of a cold engine adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state and is heated and desorbed under the assistance of a hot engine. The hydrogen obtained by desorption reaches the purity of 6N level. After most of the hydrogen is desorbed, vacuum desorption is performed to ensure that the column is completely desorbed. After the alloy separation column has completed the desorption, it enters the standby state. The secondary alloy separation unit separates a hydrogen-helium mixture with a hydrogen content of 10-1000 ppm.
[0017] S5. The hydrogen-helium mixture with a hydrogen content of 10-1000 ppm, separated by the secondary alloy separation unit, enters the tertiary alloy separation unit. In the tertiary alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working under the assistance of a chiller adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state and undergoes vacuum heating and desorption of hydrogen under the assistance of a heat engine. After the desorption of hydrogen is completed, the alloy separation column enters the standby state. The tertiary alloy separation unit separates and reduces the hydrogen concentration to 0.01-1 ppm, obtaining a high-purity helium product, which is then stored in a storage tank.
[0018] Preferably, the hydrogen outlet from the vacuum heating desorption process includes a storage tank and a pipeline flowing back to the ammonia synthesis direction, and the high-purity helium product outlet is equipped with a back pressure valve.
[0019] Preferably, the hydrogen concentration of the ammonia synthesis tail gas is 50-80%, and the helium concentration is 20-50%.
[0020] Preferably, the hydrogen-helium mixture exits from the low-pressure buffer tank 1 and is then compressed and pressurized to 1-2 MPa by the compressor 1 before entering the high-pressure buffer tank 1; the hydrogen-helium mixture exits from the low-pressure buffer tank 2 and is then compressed and pressurized to 1-2 MPa by the compressor 2 before entering the high-pressure buffer tank 2.
[0021] Preferably, the adsorption operating temperature of the primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit is -20℃ to 30℃; the desorption operating temperature of the primary alloy separation unit is 50℃ to 80℃, and the desorption absolute pressure is 0.1℃ to 1 MPa; the desorption operating temperature of the secondary alloy separation unit and the tertiary alloy separation unit is 150℃ to 300℃, and the desorption absolute pressure is 0.1℃ to 1 MPa.
[0022] In the above technical solution, the alloy separation column requires a circulating water unit and a chiller / heater unit to provide cold and heat sources. Firstly, because the alloy releases heat when absorbing hydrogen, a heat exchange system is needed to remove this released heat to ensure efficient hydrogen adsorption in the alloy separation column. Secondly, the alloy absorbs heat when releasing hydrogen, which is provided by circulating hot water or a chiller to ensure sufficient desorption and resorption in the alloy separation column. During hydrogen absorption, a hydrogen-helium mixed gas is introduced into the alloy separation column, and circulating chilled water or a chiller is used to control the operating temperature at or below room temperature. At this temperature, the hydrogen in the mixed gas is rapidly adsorbed until a dynamic adsorption equilibrium is reached. After the alloy separation column completes its operation, it is heated to a certain temperature to rapidly desorb the absorbed hydrogen. After dehydrogenation, the alloy separation column is cooled to room temperature or below, ready for the next hydrogen absorption operation.
[0023] When designing an alloy separation column, the reaction bed needs to be calculated and designed based on factors such as the gas flow rate, hydrogen content, processing time, and the thermal / kinetic characteristics of hydrogen adsorption / desorption by the material.
[0024] In the above technical solution, the alloy material is a material that can reversibly absorb and release hydrogen. When selectively absorbing hydrogen, the hydrogen reacts chemically with the material to generate hydrides, thereby storing the gaseous hydrogen in a solid form. Under changes in external temperature and pressure, it can release 6N-level hydrogen.
[0025] In the above technical solution, the desorbed hydrogen can be collected or refluxed and returned to the ammonia synthesis process.
[0026] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:
[0027] 1. In terms of performance, the alloy separation method composed of different alloys improves the hydrogen concentration from 90% to 99.9999% compared to the hollow fiber membrane separation method, and can also recover helium to obtain high-purity helium.
[0028] 2. From a cost perspective, compared to cryogenic separation, although it can also separate hydrogen and helium, cryogenic separation cannot achieve good separation results for high-concentration hydrogen mixtures. To achieve ideal separation results, pre-processing equipment is required, which consumes a lot of electricity and has a high overall cost. In contrast, alloy separation consumes less energy and can directly separate and purify high-concentration hydrogen mixtures.
[0029] 3. From a production process perspective, this device is a single skid-mounted unit, making the process simple and streamlined.
[0030] 4. From an environmental perspective, this device can separate and purify hydrogen and helium in the ammonia synthesis tail gas, avoiding emissions while generating economic benefits. Furthermore, the recovered hydrogen can be recycled and used for ammonia synthesis. Attached Figure Description
[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.
[0032] Figure 1 This is a flowchart of Embodiment 1 of the present invention;
[0033] Among them, 1-1, primary alloy separation column 1-1; 1-2, primary alloy separation column 1-2; 2-1, secondary alloy separation column 2-1; 2-2, secondary alloy separation column 2-2; 3-1, tertiary alloy separation column 3-1; 3-2, tertiary alloy separation column 3-2; 4, low-pressure buffer tank 1; 5, compressor 1; 6, high-pressure buffer tank 1; 7, filter; 8, low-pressure buffer tank 2; 9, compressor 2; 10, high-pressure buffer tank 2; 11, refrigeration and heating unit; 12, vacuum pump unit. Detailed Implementation
[0034] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.
[0035] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.
[0036] Example 1
[0037] See appendix Figure 1 This embodiment provides a device system for separating hydrogen and helium from ammonia synthesis tail gas. The device system includes a primary alloy separation unit, a secondary alloy separation unit, a tertiary alloy separation unit, a circulating water unit, a chiller / heater unit, a compressor unit, a vacuum pump unit (12), and low-pressure buffer tanks 1 (4), 2 (8), 1 (6), and 2 (10) high-pressure buffer tanks. The compressor unit includes compressor 1 (5) and compressor 2 (9).
[0038] The raw material gas inlet, low-pressure buffer tank 1 (4), compressor 1 (5), high-pressure buffer tank 1 (6), primary alloy separation unit, filter (7), low-pressure buffer tank 2 (8), compressor 2 (9), high-pressure buffer tank 2 (10), secondary alloy separation unit, and tertiary alloy separation unit are connected in sequence.
[0039] The first-level alloy separation unit, the second-level alloy separation unit, and the third-level alloy separation unit each include two sets of alloy separation columns. The alloy separation columns are divided into one for use and one for standby. The alloy separation columns of the same level are connected in parallel. The connection between the first-level alloy separation unit and the second-level alloy separation unit and the third-level alloy separation unit is connected in series.
[0040] The primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit are all equipped with flow meters, check valves, pneumatic valves, and filters on their inlet and outlet pipes.
[0041] Each alloy separation unit is equipped with a vacuum pump;
[0042] The alloy separation column is filled with packing material, all of which are alloy materials. The alloy materials are reversibly absorbable and desorbable hydrogen, and are a combination of magnesium alloy and titanium-lanthanum-nickel alloy.
[0043] This embodiment also provides a method for separating hydrogen and helium from ammonia synthesis tail gas, using the above-described apparatus system for separating hydrogen and helium from ammonia synthesis tail gas. The method for separating hydrogen and helium from ammonia synthesis tail gas includes the following steps:
[0044] S1. The synthetic ammonia tail gas containing 65% hydrogen and close to 35% helium is pretreated to remove impurities and moisture to obtain a hydrogen-helium mixture, which enters the low-pressure buffer tank 1 (4). The hydrogen-helium mixture exits from the low-pressure buffer tank 1 (4) and is then compressed and pressurized to 1.5 MPa by the compressor 1 (5) before entering the high-pressure buffer tank 1 (6).
[0045] S2. The gas coming out of the high-pressure buffer tank 1 (6) enters the first-stage alloy separation unit. In the first-stage alloy separation unit, the first-stage alloy separation column 1-1 (1-1) is first introduced and works for 4 hours until it is saturated with adsorption. Then, the first-stage alloy separation column 1-2 (1-2) is switched to adsorption. At this time, the first-stage alloy separation column 1-1 is heated to 60°C and desorbed. After heating for 1 hour, vacuum heating desorbs the hydrogen to ensure complete desorption of the alloy. In this process, the hydrogen obtained by desorption can reach the purity of 6N and its pressure is 0.25MPa. It can be collected or refluxed and returned to the process of ammonia synthesis. After the alloy separation column is desorbed, it enters the standby state. The first-stage alloy separation unit separates a hydrogen-helium mixture with a hydrogen concentration of 10%.
[0046] S3. The hydrogen-helium mixture with a hydrogen concentration of 10% separated by the primary alloy separation unit is filtered by filter (7) and enters the low-pressure buffer tank 2 (8). The hydrogen-helium mixture comes out of the low-pressure buffer tank 2 (8) and is then compressed and pressurized to 1.5MPa by compressor 2 (9) before entering the high-pressure buffer tank 2 (10).
[0047] S4. The gas coming out of the high-pressure buffer tank 2 (10) enters the secondary alloy separation unit. In the secondary alloy separation unit, the secondary alloy separation column 2-1 (2-1) is first introduced. Then, under the condition of 15°C, the hydrogen in the hydrogen-helium mixture is adsorbed. Similarly, when the adsorption of the secondary alloy separation column 2-1 is saturated, the secondary alloy separation column 2-2 (2-2) is switched to adsorption. At this time, the secondary alloy separation column 2-1 is heated to 180°C and desorbed. After heating for 1 hour, vacuum heating desorbs to ensure complete desorption of the alloy. In this process, the purity of the hydrogen obtained by desorption can reach 6N level. After the alloy separation column is desorbed, it enters the standby state. The secondary alloy separation unit separates a hydrogen-helium mixture with a hydrogen content of 50ppm.
[0048] S5. The hydrogen-helium mixture with a hydrogen content of 50 ppm separated by the secondary alloy separation unit enters the tertiary alloy separation unit. In the tertiary alloy separation unit, the hydrogen is first introduced into the tertiary alloy separation column 3-1 (3-1). Then, under the condition of 25°C, the hydrogen in the hydrogen-helium mixture is adsorbed. Similarly, when the adsorption of the tertiary alloy separation column 3-1 is saturated, the adsorption is switched to the tertiary alloy separation column 3-2 (3-2). At this time, the tertiary alloy separation column 3-1 is heated to 200°C and desorbed. After heating for 1 hour, vacuum heating desorption is performed to ensure complete desorption of the alloy. After desorption, the alloy separation column enters the standby state. The tertiary alloy separation unit separates and reduces the hydrogen concentration to 0.05 ppm to obtain high-purity helium product, which is then stored in a storage tank.
[0049] Furthermore, the hydrogen outlet from the vacuum heating desorption process includes a storage tank and a pipeline that flows back to the ammonia synthesis direction, and the high-purity helium product outlet is equipped with a back pressure valve.
[0050] Furthermore, the absolute pressure for the analysis of the primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit is 0.3 MPa;
[0051] Furthermore, the alloy separation column requires a circulating water unit and a chiller / heater (11) to provide a cold source and a heat source. Firstly, because the alloy releases a certain amount of heat when absorbing hydrogen, it needs to be removed through a heat exchange system to ensure the efficient hydrogen adsorption of the alloy separation column. Secondly, the alloy needs to absorb a certain amount of heat when releasing hydrogen, so the required heat is provided by circulating hot water or a chiller to ensure the full desorption and desorption of the alloy separation column. When absorbing hydrogen, a hydrogen-helium mixed gas is introduced into the alloy separation column, and the working temperature is controlled at room temperature or below using circulating cold water or a chiller. At this time, the hydrogen in the mixed gas is quickly adsorbed until a dynamic adsorption equilibrium is reached. After the alloy separation column has finished working, it is heated to a certain temperature to quickly desorb the hydrogen it has absorbed. After dehydrogenation, the alloy separation column is cooled to room temperature or below to wait for the next hydrogen absorption operation.
[0052] Furthermore, the alloy material is a material that can reversibly absorb and release hydrogen. When selectively absorbing hydrogen, the hydrogen reacts chemically with the material to generate hydrides, thereby storing the gaseous hydrogen in a solid form. Under changes in external temperature and pressure, it can release 6N of hydrogen.
[0053] In summary, from a performance perspective, the alloy separation method composed of different alloys, compared to the hollow fiber membrane separation method, improves the hydrogen concentration from 90% to 99.9999%, and can also recover helium to obtain high-purity helium. From a cost perspective, this invention has low energy consumption and can directly separate and purify high-concentration hydrogen mixtures. From a production process perspective, this device is integrated into a skid, simplifying the process. From an environmental perspective, this device can separate and purify hydrogen and helium in ammonia synthesis tail gas, avoiding emissions while generating economic benefits, and the recovered hydrogen can be recycled and used for ammonia synthesis.
[0054] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.
[0055] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the appended claims.
Claims
1. A device system for separating hydrogen and helium from ammonia synthesis tail gas, characterized in that, The device system includes a primary alloy separation unit, a secondary alloy separation unit, a tertiary alloy separation unit, a circulating water unit, a chiller / heater unit, a compressor unit, a vacuum pump unit, and low-pressure buffer tanks 1 and 2 and high-pressure buffer tanks 1 and 2. The compressor unit includes compressor 1 and compressor 2. The raw material gas inlet, low-pressure buffer tank 1, compressor 1, high-pressure buffer tank 1, primary alloy separation unit, filter, low-pressure buffer tank 2, compressor 2, high-pressure buffer tank 2, secondary alloy separation unit, and tertiary alloy separation unit are connected in sequence. The primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit each include two or more sets of alloy separation columns. The alloy separation columns are either used with one standby or used with multiple standby columns. The alloy separation columns of the same level are connected in parallel. The connection between the primary alloy separation unit and the secondary alloy separation unit and the tertiary alloy separation unit is connected in series. The primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit are all equipped with flow meters, check valves, pneumatic valves, and filters on their inlet and outlet pipes. Each alloy separation unit is equipped with a vacuum pump; The alloy separation column is filled with packing material, all of which are alloy materials. The alloy materials are reversibly absorbable and desorbable hydrogen, and are selected from one or more alloys selected from magnesium alloys, titanium alloys, or lanthanum-nickel alloys.
2. A method for separating hydrogen and helium from ammonia synthesis tail gas, characterized in that, The apparatus system for separating hydrogen and helium from ammonia synthesis tail gas as described in claim 1, and the method for separating hydrogen and helium from ammonia synthesis tail gas, include the following steps: S1. The raw material gas for ammonia synthesis is pretreated to remove impurities and moisture to obtain a hydrogen-helium mixture that enters a low-pressure buffer tank 1. The hydrogen-helium mixture exits from the low-pressure buffer tank 1 and is then compressed and pressurized by compressor 1 before entering the high-pressure buffer tank 1. S2. The gas from the high-pressure buffer tank 1 enters the first-stage alloy separation unit. In the first-stage alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working with the assistance of circulating cold water adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state. With the assistance of circulating hot water, the hydrogen is desorbed by heating and desorption. The hydrogen obtained by desorption reaches the purity of 6N level. After most of the hydrogen is desorbed, vacuum desorption is performed to ensure that the column is completely desorbed. After the alloy separation column has completed the desorption, it enters the standby state. The first-stage alloy separation unit separates a hydrogen-helium mixture with a hydrogen concentration of 5-15%. S3. The hydrogen-helium mixture with a hydrogen concentration of 5-15% separated by the primary alloy separation unit is filtered and enters the low-pressure buffer tank 2. The hydrogen-helium mixture exits from the low-pressure buffer tank 2 and is then compressed and pressurized by the compressor 2 before entering the high-pressure buffer tank 2. S4. The gas from the high-pressure buffer tank 2 enters the secondary alloy separation unit. In the secondary alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working under the assistance of a cold engine adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state and is heated and desorbed under the assistance of a hot engine. The hydrogen obtained by desorption reaches the purity of 6N level. After most of the hydrogen is desorbed, vacuum desorption is performed to ensure that the column is completely desorbed. After the alloy separation column has completed the desorption, it enters the standby state. The secondary alloy separation unit separates a hydrogen-helium mixture with a hydrogen content of 10-1000 ppm. S5. The hydrogen-helium mixture with a hydrogen content of 10-1000 ppm, separated by the secondary alloy separation unit, enters the tertiary alloy separation unit. In the tertiary alloy separation unit, one alloy separation column is first introduced for separation, while the other alloy separation columns are in standby mode. After the alloy separation column working under the assistance of a chiller adsorbs hydrogen to the rated value, the device switches to other alloy separation columns for adsorption. At this time, the alloy separation column that has adsorbed hydrogen to the rated value enters the regeneration state and undergoes vacuum heating and desorption of hydrogen under the assistance of a heat engine. After the desorption of hydrogen is completed, the alloy separation column enters the standby state. The tertiary alloy separation unit separates and reduces the hydrogen concentration to 0.01-1 ppm, obtaining a high-purity helium product, which is then stored in a storage tank.
3. The method for separating hydrogen and helium from ammonia synthesis tail gas as described in claim 2, characterized in that, The hydrogen outlet from the vacuum heating desorption process includes a storage tank and a pipeline that returns to the direction of ammonia synthesis. The high-purity helium product outlet is equipped with a back pressure valve.
4. The method for separating hydrogen and helium from ammonia synthesis tail gas as described in claim 2, characterized in that, The hydrogen concentration of the ammonia synthesis tail gas is 50-80%, and the helium concentration is 20-50%.
5. The method for separating hydrogen and helium from ammonia synthesis tail gas as described in claim 2, characterized in that, The hydrogen-helium mixture exits from the low-pressure buffer tank 1 and is then compressed and pressurized to 1-2 MPa by the compressor 1 before entering the high-pressure buffer tank 1; the hydrogen-helium mixture exits from the low-pressure buffer tank 2 and is then compressed and pressurized to 1-2 MPa by the compressor 2 before entering the high-pressure buffer tank 2.
6. The method for separating hydrogen and helium from ammonia synthesis tail gas as described in claim 2, characterized in that, The adsorption operating temperature of the primary alloy separation unit, the secondary alloy separation unit, and the tertiary alloy separation unit is -20℃ to 30℃; the desorption operating temperature of the primary alloy separation unit is 50℃ to 80℃, and the absolute desorption pressure is 0.1℃ to 1 MPa; the desorption operating temperature of the secondary alloy separation unit and the tertiary alloy separation unit is 150℃ to 300℃, and the absolute desorption pressure is 0.1℃ to 1 MPa.