Adsorbent selection method, pressure swing adsorption method, adsorbent selection system, pressure swing adsorption system, and computer-readable storage medium

Abstract

An adsorbent selection method, a pressure swing adsorption method, and a system thereof are disclosed. The selection method includes the steps of: acquiring a slope of an adsorption isotherm at an initial pressure for each of a plurality of adsorbents for a target adsorbate, the adsorption isotherm being a curve showing an adsorption amount that changes depending on pressure at a specific temperature; acquiring an adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and specific pressure; and selecting a target adsorbent from the plurality of adsorbents for adsorbing the target adsorbate according to the slope and adsorption amount of each of the adsorbents. The pressure swing adsorption cycle can be optimized during pressure swing adsorption, the amount of adsorbent used can be reduced, and the operation and production costs of pressure swing adsorption can be reduced.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Chinese Patent Application No. 202111681815.7, filed on December 31, 2021, the contents of which are incorporated herein by reference. [Technical Field]

[0002] FIELD OF THE INVENTION Embodiments of the present invention relate to the technical field of adsorptive separation, and more particularly to methods for selecting adsorbents, pressure swing adsorption methods, and systems thereof. [Background technology]

[0003] Pressure swing adsorption technology can be used not only for the purification of gases such as hydrogen, helium, and nitrogen, but also for industrial processes such as carbon dioxide capture and light hydrocarbon recovery. Pressure swing adsorption varies depending on the application scenario, and the adsorbent selected can adsorb the impurities that need to be removed or the products that need to be produced. The impurities or products adsorbed by the adsorbent are both called adsorbates. The adsorbent, control process, and equipment are key to the application of pressure swing adsorption technology in production.

[0004] Selecting adsorbents according to various adsorbates, combining corresponding control processes, and selecting reliable equipment are common processes for achieving an optimized production plan for pressure swing adsorption. In general, pressure swing adsorption involves filling each tower with the same type and weight of adsorbent, and sequentially switching between two or more towers to achieve continuous production. Filling each adsorption tower with a fixed amount of adsorbent can extend the adsorption cycle and improve product recovery. Reducing the adsorbent loading can shorten the adsorption cycle, ensuring product recovery and reducing the equipment footprint.

[0005] In the prior art, the adsorbents for different adsorbates are mainly selected empirically, so that sufficient adsorption usually requires excessive loading of the adsorbent and a long adsorption time.

[0006] From the perspective of sustainable development, it is more preferable to reduce the amount of adsorbent used and the volume of the adsorption tower, thereby reducing the installation area of ​​the device, while ensuring the overall performance of the pressure swing adsorption device. Therefore, in gas pressure swing adsorption processes using the same feedstock, how to optimize the pressure swing adsorption cycle, reduce the amount of adsorbent, and reduce the installation area and total weight of the device has become an urgent issue. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an adsorbent selection method, a pressure swing adsorption method, and a system thereof that can select a target adsorbent based on the slope of the adsorption isotherm at the initial pressure and the adsorption capacity of the adsorbent for the target adsorbate at a specific temperature and a specific pressure, thereby optimizing the pressure swing adsorption cycle during pressure swing adsorption, reducing the amount of adsorbent used, and reducing the operating and production costs of pressure swing adsorption. [Means for solving the problem]

[0008] In order to achieve the above object, a first aspect of the present invention provides a method for selecting an adsorbent, comprising the steps of: acquiring a slope at an initial pressure of an adsorption isotherm of each of a plurality of adsorbents for a target adsorbate, the adsorption isotherm being a curve along which the adsorption amount changes depending on the pressure at a specific temperature; acquiring the adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and specific pressure; and selecting a target adsorbent from the plurality of adsorbents for adsorbing the target adsorbate according to the slope and adsorption amount of each of the adsorbents.

[0009] Preferably, the step of selecting a target adsorbent from the plurality of adsorbents for adsorbing the target adsorbate includes the steps of: determining, from the slope of each adsorbent, the shortest time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent; selecting, based on the determined shortest time, a specific adsorbent from the plurality of adsorbents whose corresponding shortest time is equal to or shorter than a predetermined time; determining the product of the slope and the adsorption amount of the specific adsorbent; and selecting, as the target adsorbent, the adsorbent corresponding to the largest product.

[0010] Preferably, the step of determining the minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent includes the steps of: setting the shortest time corresponding to the adsorbent to be equal to or greater than the first shortest time when the slope of the adsorbent is greater than the first slope and equal to or less than the second slope; setting the shortest time corresponding to the adsorbent to be equal to or greater than the second shortest time when the slope of the adsorbent is greater than the second slope and equal to or less than the third slope; setting the shortest time corresponding to the adsorbent to be equal to or greater than the third shortest time when the slope of the adsorbent is greater than the third slope and equal to or less than the fourth slope; or setting the shortest time corresponding to the adsorbent to be equal to or greater than the fourth shortest time when the slope of the adsorbent is greater than the fourth slope and equal to or less than the fifth slope; wherein the first slope, the second slope, the third slope, the fourth slope, and the fifth slope gradually increase, and the first shortest time, the second shortest time, the third shortest time, and the fourth shortest time gradually increase.

[0011] Preferably, when the first slope is 1, the second slope is 10, the third slope is 20, the fourth slope is 30, and the fifth slope is 50, the first minimum time is 0.05 s, the second minimum time is 3 s, the third minimum time is 9 s, and the fourth minimum time is 24 s.

[0012] Preferably, the step of determining the minimum time t for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent comprises:

number

[0013] Preferably, T is 40 or less.

[0014] Preferably, the selection method further includes the steps of determining the determined shortest time as an adsorption time, and determining the amount of the target adsorbent from the amount of the target adsorbate introduced into the adsorption tower within the adsorption time and the adsorption amount of the target adsorbent.

[0015] Preferably, the step of acquiring the slope of the adsorption isotherm at the initial pressure for each of the plurality of adsorbents for the target adsorbate is executed when predetermined preconditions are satisfied, the predetermined preconditions including that, at each pressure, the absolute value of the difference between the adsorption amount of the adsorption isotherm and the desorption isotherm of each of the adsorbents for the target adsorbate is equal to or less than a predetermined ratio of the adsorption amount of the adsorption isotherm, and the desorption isotherm is a curve along which the desorption amount changes depending on the pressure at the specific temperature.

[0016] Preferably, the predetermined preconditions further include that the adsorption amount of the adsorption isotherm of each of the adsorbents for the target adsorbate at each pressure is equal to or less than the adsorption amount of the desorption isotherm of the adsorbent.

[0017] Preferably, the specific temperature is 10°C to 40°C.

[0018] Preferably, the initial pressure is 10 kPa or less.

[0019] Preferably, the adsorbent is selected from microporous molecular sieves, MOFs, carbon molecular sieves, or silica gel.

[0020] According to the above technical solution, the present invention selects a target adsorbent from among a plurality of adsorbents for adsorbing the target adsorbate based on the slope of the adsorption isotherm of each adsorbent at the initial pressure for the target adsorbate and the adsorption capacity of each adsorbent for the target adsorbate at the specific temperature and pressure. This enables the pressure swing adsorption cycle to be optimized during pressure swing adsorption, the amount of adsorbent used, and the operating and production costs of pressure swing adsorption to be reduced.

[0021] A second aspect of the present invention provides a pressure swing adsorption method comprising the steps of selecting a target adsorbent for adsorbing one or more target adsorbates according to the adsorbent selection method described above, and performing pressure swing adsorption of the one or more target adsorbates using the target adsorbent.

[0022] Preferably, the pressure swing adsorption method further includes the step of controlling the process sequence of pressure swing adsorption by an integrated rotary valve when the slope of the adsorption isotherm of the target adsorbent at the initial pressure point is greater than a first preset slope and less than or equal to a second preset slope, or the step of controlling the process sequence of pressure swing adsorption by a sequencing valve when the slope of the adsorption isotherm of the target adsorbent at the initial pressure point is greater than the second preset slope and less than or equal to a third preset slope.

[0023] Preferably, when the target adsorbent is a plurality of target adsorbents, the pressure swing adsorption method further includes a step of grading the plurality of target adsorbents, and the step of performing pressure swing adsorption on the one or more target adsorbates at a specific temperature using the target adsorbents includes a step of performing pressure swing adsorption on the one or more target adsorbates at the specific temperature using the graded plurality of target adsorbents.

[0024] Preferably, the pressure swing adsorption method further includes a step of setting a minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption based on the slope of the adsorption isotherm of the adsorbent among the plurality of target adsorbents that has the largest slope at the initial pressure.

[0025] According to the above technical solution, the adsorbent selection method involves selecting a target adsorbent for adsorbing one or more target adsorbates, and then using the target adsorbent to perform pressure swing adsorption on the one or more target adsorbates at a specific temperature, thereby reducing the amount of adsorbent used and optimizing the pressure swing adsorption cycle, thereby reducing the operating and production costs of pressure swing adsorption.

[0026] A third aspect of the present invention provides a method for detecting a target adsorbate using a method comprising: a memory for storing adsorption isotherms of a plurality of adsorbents for a target adsorbate; an operation of acquiring a slope of an adsorption isotherm of each of the adsorbents for the target adsorbate at an initial pressure, the adsorption isotherm being a curve showing how the amount of adsorption changes depending on the pressure at a specific temperature; and an operation of acquiring the adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and the specific pressure; and an operation of selecting a target adsorbent for adsorbing the target adsorbate from the plurality of adsorbents according to the gradient and adsorption amount of each of the adsorbents; and a processor configured to execute the steps of:

[0027] The details and advantages of the adsorbent selection system according to the present invention can be found in the above description of the adsorbent selection method, and therefore will not be described in detail here.

[0028] A fourth aspect of the present invention provides a pressure swing adsorption system including an adsorbent selection system for selecting a target adsorbent for adsorbing one or more target adsorbates, as described above, and an adsorption apparatus for performing pressure swing adsorption of the one or more target adsorbates at a specified temperature using the target adsorbent.

[0029] The details and advantages of the pressure swing adsorption system according to the present invention can be found in the above description of the pressure swing adsorption method, and will not be described in detail here.

[0030] A fifth aspect of the present invention provides a computer-readable storage medium having stored thereon a computer program that, when executed by a processor, implements the above-described adsorbent selection method and / or the above-described pressure swing adsorption method.

[0031] Other features and advantages of the present invention are described in detail in the detailed description section that follows. [Brief explanation of the drawings]

[0032] The drawings are intended to provide a further understanding of embodiments of the invention, constitute a part of the specification, and together with the following detailed description explain, but do not limit, embodiments of the invention. [Figure 1] 1 is a flowchart of a method for selecting an adsorbent according to one embodiment of the present invention. [Figure 2] 1 is a flowchart illustrating a process for selecting a target adsorbent for adsorbing the target adsorbate from among the plurality of adsorbents according to an embodiment of the present invention. [Figure 3] The adsorption and desorption isotherms of an adsorbent for a given adsorbate. [Figure 4] 4 shows the slope curve of the adsorption isotherm and the slope curve of the desorption isotherm in FIG. [Figure 5] The adsorption and desorption isotherms of an adsorbent for a given adsorbate. [Figure 6] 6 shows the slope curve of the adsorption isotherm and the slope curve of the desorption isotherm in FIG. 5. [Figure 7] The adsorption and desorption isotherms of a given adsorbate for another adsorbent. [Figure 8] 8 shows the slope curve of the adsorption isotherm and the slope curve of the desorption isotherm in FIG. [Figure 9]The adsorption and desorption isotherms of a given adsorbate for another adsorbent. [Figure 10] 10 shows the slope curve of the adsorption isotherm and the slope curve of the desorption isotherm in FIG. [Figure 11] 1 shows the adsorption isotherm of an adsorbent for a certain adsorbate and the slope curve of the adsorption isotherm. [Figure 12] 1 shows the adsorption isotherm of an adsorbent for a certain adsorbate and the slope curve of the adsorption isotherm. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It should be understood that the specific embodiments described herein are merely for the purpose of explaining and interpreting the present invention, and are not intended to limit the present invention.

[0034] 1 is a flowchart of an adsorbent selection method according to one embodiment of the present invention. As shown in FIG. 1, the selection method may include step S101 of acquiring a slope of an adsorption isotherm at an initial pressure for each of a plurality of adsorbents for a target adsorbate, where the adsorption isotherm is a curve indicating that the adsorption amount changes depending on the pressure at a specific temperature, step S102 of acquiring the adsorption amount of each adsorbent for the target adsorbate at the specific temperature and specific pressure, and step S103 of selecting a target adsorbent from the plurality of adsorbents for adsorbing the target adsorbate based on the slope and adsorption amount of each adsorbent.

[0035] In this example, by selecting the type of adsorbent for the target adsorbate, a short-period pressure swing adsorption cycle can be achieved, optimizing the steps of the pressure swing adsorption process and reducing the amount of adsorbent used. This effectively reduces the installation area and weight of a pressure swing adsorption apparatus for the same production scale (same amount of feed gas with the same impurity composition and content), thereby reducing the operating and production costs of pressure swing adsorption.

[0036] Before performing step S101, the degree of overlap between the adsorption isotherm and desorption isotherm of each adsorbent for the target adsorbate may be obtained, and then a judgment may be made on the degree of overlap. If the degree of overlap is good, it indicates that the target adsorbate has been sufficiently desorbed and the desorption capacity is high, and step S101 is performed; otherwise, the corresponding subsequent step for the adsorbent is not performed.

[0037] Here, the degree of overlap between the adsorption isotherm and desorption isotherm refers to the degree of overlap between the adsorption amounts of the two curves at the same pressure. Specifically, the adsorption isotherm refers to a static adsorption isotherm, which is characterized by its high reproducibility, ease of acquisition, and applicability to the evaluation of the performance characteristics of almost all adsorbents. The desorption isotherm is the adsorption amount isotherm obtained by starting desorption under reduced pressure at the same temperature conditions for an adsorbent that has completed a static adsorption isotherm test. The adsorption isotherm test method is as follows: the horizontal axis represents pressure in bar, and the vertical axis represents adsorption amount in ml / g. The obtained adsorption isotherm represents the equilibrium adsorption amount per unit mass of adsorbent at a constant adsorbate pressure.

[0038] In one embodiment, the step of acquiring the slope of the adsorption isotherm at the initial pressure for each of the plurality of adsorbents for the target adsorbate (i.e., step S101) is executed when a preset precondition is met.

[0039] The predetermined precondition may include that, at each pressure, the absolute value of the difference between the adsorption amount of the adsorption isotherm and the adsorption amount of the desorption isotherm of each of the adsorbents for the target adsorbate is equal to or less than a predetermined ratio (e.g., 15%) of the adsorption amount of the adsorption isotherm.

[0040] The desorption isotherm is a curve showing the change in desorption amount depending on the pressure at the specific temperature, which is room temperature (for example, 10°C to 40°C), preferably 25°C.

[0041] Preferably, the predetermined preconditions may further include that the adsorption amount of the target adsorbate in the adsorption isotherm of each adsorbent at each pressure is equal to or less than the adsorption amount in the desorption isotherm of each adsorbent, thereby enabling complete and rapid desorption of the adsorbed adsorbate.

[0042] In step S101, the slope of the adsorption isotherm at the initial pressure for each of the plurality of adsorbents for the target adsorbate is obtained.

[0043] Here, the adsorption isotherm is a curve showing the change in adsorption amount depending on pressure at a specific temperature. The specific temperature is room temperature (e.g., 10°C to 40°C), preferably 25°C. In this specification, unless a specific temperature value is specified, the default value is 25°C.

[0044] The initial pressure is 10 kPa or less. For different adsorbents, the pressure value may be set to the same value.

[0045] The adsorbent is selected from microporous molecular sieves, MOFs, carbon molecular sieves, specialized adsorbents in which a specific material (e.g., a metal material such as Cu / Zn) is loaded on a microporous molecular sieve, MOFs, or carbon molecular sieve, and silica gel.

[0046] For example, for shaped adsorbents, the particle size ranges between 0.4 mm and 2.5 mm. Shaped adsorbents can be spherical, strip-like, cylindrical, or core-shell shaped. For structured adsorbents, the thickness of the adsorbent coating ranges from 50 μm to 400 μm. Structured adsorbents generally refer to adsorbent powder coated on a porous support, which may be a metal sintered porous material, alumina sintered porous material, organic glass fiber porous material, etc.

[0047] Specifically, first, the static adsorption isotherm and desorption isotherm of the adsorbent at a specific temperature (see, for example, Figures 3, 5, 7, 9, and 11-12) are measured, then the differential values ​​(slopes of the tangents) of the fitting curves of the adsorption isotherm and desorption isotherm are calculated, the tangent slopes at each point are obtained, and an isotherm slope curve (see Figures 4, 6, 8, and 10-12) is obtained, thereby obtaining the slope of each adsorption isotherm at the initial pressure. Of course, only the slope at the initial pressure may be obtained.

[0048] In step S102, the adsorption amount of each adsorbent for the target adsorbate at the specific temperature and specific pressure is acquired.

[0049] The adsorption amount of each adsorbent for the target adsorbate at the specific temperature and specific pressure (e.g., 1 bar) can be obtained from the adsorption isotherm of each adsorbent for the target adsorbate. In this specification, if the specific pressure value is not specifically specified, the default value may be 1 bar. Of course, the specific pressure refers to a reasonable pressure used to measure the adsorption amount, and can be reasonably set according to actual conditions and is not limited to 1 bar.

[0050] In step S103, a target adsorbent for adsorbing the target adsorbate is selected from the plurality of adsorbents according to the gradient and adsorption amount of each adsorbent.

[0051] As shown in FIG. 2, step S103 of selecting a target adsorbent for adsorbing the target adsorbate from the plurality of adsorbents may include the following steps S201 to S204.

[0052] In step S201, the shortest time for each decomposition step sequence in the cycle period of pressure swing adsorption for each adsorbent is determined from the gradient of each adsorbent.

[0053] The entire cycle period (adsorption period) can be determined from the determined shortest time of each decomposition step sequence.

[0054] In one embodiment, step S201 of determining the shortest time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent includes the steps of: setting the shortest time corresponding to the adsorbent to be equal to or greater than the first shortest time if the slope of the adsorbent is greater than the first slope and less than or equal to the second slope; setting the shortest time corresponding to the adsorbent to be equal to or greater than the second shortest time if the slope of the adsorbent is greater than the second slope and less than or equal to the third slope; setting the shortest time corresponding to the adsorbent to be equal to or greater than the third shortest time if the slope of the adsorbent is greater than the third slope and less than or equal to the fourth slope; or setting the shortest time corresponding to the adsorbent to be equal to or greater than the fourth shortest time if the slope of the adsorbent is greater than the fourth slope and less than or equal to the fifth slope.

[0055] Here, the first slope, the second slope, the third slope, the fourth slope, and the fifth slope gradually increase, and the first shortest time, the second shortest time, the third shortest time, and the fourth shortest time gradually increase.

[0056] When the first slope is 1, the second slope is 10, the third slope is 20, the fourth slope is 30, and the fifth slope is 50, the first shortest time is 0.05 seconds, the second shortest time is 3 seconds, the third shortest time is 9 seconds, and the fourth shortest time is 24 seconds.

[0057] Specifically, if the slope of the adsorption isotherm of an adsorbent at the initial pressure point for the target adsorbate is greater than 50, the adsorbent is determined to be unsuitable for a continuous production process using ambient temperature pressure swing adsorption. If the slope of the adsorption isotherm of an adsorbent at the initial pressure point for the target adsorbate is 50 or less, the adsorbent is suitable for ambient temperature pressure swing adsorption, and periodic adsorption and regeneration cycles (i.e., reduced pressure regeneration processes) can be achieved within an appropriate period of pressure swing adsorption.

[0058] For example, when the slope 1 < k0 ≤ 10 at the initial pressure point of the adsorption isotherm of the selected adsorbent, the time for each decomposition step sequence in the cycle period of pressure swing adsorption is 0.05 s or more; when the slope 10 < k0 ≤ 20 at the initial pressure point of the adsorption isotherm of the selected adsorbent, the time for each decomposition step sequence in the cycle period of pressure swing adsorption is 3 s or more; when the slope 20 < k0 ≤ 30 at the initial pressure point of the adsorption isotherm of the selected adsorbent, the time for each decomposition step sequence in the cycle period of pressure swing adsorption is 9 s or more; when the slope 30 < k0 ≤ 50 at the initial pressure point of the adsorption isotherm of the selected adsorbent, the time for each decomposition step sequence in the cycle period of pressure swing adsorption is 24 s or more.

[0059] When the measured adsorption isotherm and desorption isotherm of the adsorbent for a certain adsorbate, and the corresponding slope curves are as shown in FIGS. 1 and 2, the adsorbent is applicable to short-cycle pressure swing adsorption, and the time for each decomposition step sequence in the cycle period may be 0.05 s or more.

[0060] When the measured adsorption isotherm and desorption isotherm of the adsorbent for a certain adsorbate, and the corresponding slope curves are as shown in FIGS. 3 and 4, the adsorbent can be applied to short-cycle pressure swing adsorption with the time for each decomposition step sequence in the cycle period being 3 s or more.

[0061] When the measured adsorption isotherm and desorption isotherm of the adsorbent for a certain adsorbate, and the corresponding slope curves are as shown in FIGS. 5 and 6, the adsorbent can be applied to short-cycle pressure swing adsorption with the time for each decomposition step sequence in the cycle period being 9 s or more.

[0062] When the measured adsorption isotherm and desorption isotherm of the adsorbent for a certain adsorbate, and the corresponding slope curves are as shown in FIGS. 7 and 8, the adsorbent can be applied to short-cycle pressure swing adsorption with the time for each decomposition step sequence in the cycle period being 24 s or more.

[0063] When a gas source contains multiple types of adsorbate components, the adsorbent can be selected and graded by the above method. The cycle period applicable to the composite bed for grading multiple types of adsorbents is determined by the adsorbent with the longest time required for the decomposition step sequence.

[0064] When the measured adsorption isotherm and the tangent slope curve of the adsorption isotherm of the adsorbent for a certain adsorbate are shown in FIG. 9 or FIG. 10, since the desorption of the adsorbent cannot occur at the measurement temperature, the desorption isotherm at the same temperature cannot be obtained. Also, the slope at the initial pressure point of the adsorption isotherm of the adsorbent is greater than 50, and the adsorbent is not applicable to the process of normal temperature pressure swing adsorption.

[0065] Therefore, the above embodiments can be applied to the vacuum regeneration process. In other processes, k0 may be in other appropriate ranges, for example, 50 < k0 ≤ 200. Also, for various sub-ranges, the time of each decomposition step sequence in the cycle period of the pressure swing adsorption corresponding to the sub-range can be determined.

[0066] In another embodiment, the step S201 for determining the shortest time t (unit: s) of each decomposition step sequence in the cycle period of the pressure swing adsorption of each adsorbent is

Number

[0067] Since this embodiment can be applied to the process of short-cycle pressure swing adsorption, T is 40 or less (in this specification, unless otherwise specified, the default is T = 40). When k0 is obtained by step S101, the shortest time t of the decomposition step sequence corresponding to each adsorbent can be determined by the above formula.

[0068] Therefore, the above embodiment has a very wide range of application, and is not only applicable to the reduced pressure regeneration process (without vacuum pumping), but also to the selection and grading of adsorbents using the vacuum pumping and purging process, and the shortest time determined accordingly is also very accurate.

[0069] In step S202, a specific adsorbent is selected from the plurality of adsorbents based on the determined shortest time.

[0070] Here, the shortest time corresponding to the specific adsorbent is equal to or shorter than a predetermined time, which can be reasonably set according to the actual situation, for example, the predetermined time can be set to 15.10 seconds (corresponding slope is 24 seconds).

[0071] [Table 1]

[0072] The shortest time in Table 1 can be calculated using the formula for t. In Table 1, the shortest time for each of the three adsorbents is less than 15.10 seconds, allowing for the selection of three adsorbents. This step optimizes the pressure swing adsorption cycle and achieves high-speed adsorption.

[0073] In step S203, the product of the slope and the adsorption amount of the specific adsorbent is determined.

[0074] For example, as shown in Table 2, the corresponding product is determined from the slope and adsorption amount of each of the following adsorbents.

[0075] [Table 2]

[0076] In step S204, the adsorbent corresponding to the maximum product is selected as the target adsorbent.

[0077] For example, molecular sieve 1 is selected as the target adsorbent because the product of the slope of the adsorption isotherm at the initial pressure and the adsorption amount (1 bar / 25°C) is the largest. This step allows the target adsorbate to be effectively adsorbed using a small amount of the target adsorbent, thereby reducing the volume of the adsorption tower.

[0078] Therefore, the above-described embodiments optimize the pressure swing adsorption cycle, reduce the amount of adsorbent used, and reduce the operating and production costs of the pressure swing adsorption system, thereby ensuring the productivity of the pressure swing adsorption system and the recovery rate of the product.

[0079] In one embodiment, the selection method further includes the steps of determining the shortest time corresponding to the target adsorbent as an adsorption time, and determining the amount of the target adsorbent from the amount of the target adsorbate introduced into the adsorption tower within the adsorption time and the adsorption amount of the target adsorbent.

[0080] For example, the shortest time corresponding to the target adsorbent determined in step S201 is determined as the adsorption time, and then the amount of the target adsorbate introduced into the adsorption tower within the adsorption time is determined and combined with the adsorption amount of the target adsorbent, thereby determining the amount of the target adsorbate.

[0081] In each of the above examples, the type of adsorbent can be selected for various target adsorbates, and the adsorbent candidates are not particularly limited, so the range of application is wide.

[0082] As described above, an innovation of the present invention is to select a target adsorbent from among a plurality of adsorbents for adsorbing the target adsorbate based on the slope of the adsorption isotherm of each of the adsorbents for the target adsorbate at the initial pressure and the adsorption capacity of each adsorbent for the target adsorbate at the specific temperature and pressure, thereby optimizing the pressure swing adsorption cycle during pressure swing adsorption, reducing the amount of adsorbent used, and reducing the operating and production costs of pressure swing adsorption.

[0083] One embodiment of the present invention also provides a pressure swing adsorption method, which includes a step of selecting a target adsorbent for adsorbing one or more target adsorbates by the method for selecting the adsorbent, and a step of performing pressure swing adsorption at a specific temperature on the one or more target adsorbates using the target adsorbent.

[0084] In one embodiment, when the slope at the initial pressure point of the adsorption isotherm of the target adsorbent is greater than a first preset slope and less than or equal to a second preset slope, the pressure swing adsorption process sequence is controlled by an integrated rotary valve, or when the slope at the initial pressure point of the adsorption isotherm of the target adsorbent is greater than the second preset slope and less than or equal to a third preset slope, the pressure swing adsorption method further includes a step of controlling the pressure swing adsorption process sequence by a sequencing valve.

[0085] For example, when the slope at the initial pressure of the adsorption isotherm of the selected adsorbent satisfies 1 < k0 ≤ 20, very accurate control can be achieved by realizing the process sequence with an integrated rotary valve. When the slope at the initial pressure of the adsorption isotherm of the selected adsorbent satisfies 20 < k0 ≤ 50, the process sequence is realized by a sequencing valve.

[0086] In another embodiment, when the target adsorbent is a plurality of target adsorbents, the pressure swing adsorption method further includes a step of grading the plurality of target adsorbents, and the step of performing pressure swing adsorption at a specific temperature on the one or more target adsorbates using the target adsorbent includes a step of performing pressure swing adsorption at the specific temperature on the one or more target adsorbates using the plurality of target adsorbents after grading.

[0087] The pressure swing adsorption method further includes a step of setting a minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption based on the slope of the adsorption isotherm of the adsorbent among the plurality of target adsorbents that has the largest slope at the initial pressure.

[0088] Specifically, when there are multiple target adsorbates, for example, when the source gas contains multiple components, an adsorbent is selected for each of the multiple target adsorbates, and the selected multiple adsorbents are graded. In one embodiment, grading refers to providing multiple target adsorbent beds according to the molecular weight of the target adsorbates, and adsorbing the corresponding target adsorbates in descending order according to their molecular weight. Generally, the same adsorbent is more likely to adsorb adsorbates with larger molecular weights, but is less likely to desorb impurities with larger molecular weights. Therefore, using graded adsorbents to adsorb adsorbates in order according to molecular weight is advantageous for desorption of the adsorbents.

[0089] Furthermore, the shortest time for each decomposition step sequence in a pressure swing adsorption cycle is determined by the target adsorbent with the largest initial pressure slope of the adsorption isotherm among the graded target adsorbents. The relationship between the shortest time for each decomposition step sequence in a pressure swing adsorption cycle for each adsorbent and the initial pressure slope of the adsorption isotherm for each adsorbent is described in the above technical solution and will not be described in detail here.

[0090] Furthermore, the cyclic process sequence for pressure swing adsorption includes the time-sequential steps of adsorption, pressure equalization depressurization, desorption, and pressure equalization repressurization.

[0091] Furthermore, a process is used in which the number of adsorption towers and the number of towers in the adsorption state and the number of pressure equalization times are 10-3-4, 12-3-6, 4-1-2, 6-1-2, 8-2-3, 8-2-2, or 9-2-3.

[0092] This example also provides an adsorbent grading method, which is a simple way to implement an adsorbent grading scheme for short cycle pressure swing adsorption.

[0093] The short-cycle pressure swing adsorption methods of the above examples do not require additional process sequences to compensate for the desorption performance of the adsorbent, and various pressure swing adsorption cycle period requirements can be met by selecting the adsorbent type. The productivity of the adsorbent bed is improved, and the energy consumption of the regeneration process is reduced. For example, the amount of purge regeneration gas used is reduced, the power consumption for vacuum pumping is reduced, and even vacuum pumping is omitted. This reduces the energy consumption of the entire process and effectively improves overall efficiency.

[0094] Taking a typical 8-2-2 process as an example (i.e., eight adsorption towers, two of which are simultaneously in an adsorption step sequence, with depressurization and pressurization occurring twice per cycle), a pressure swing adsorption cycle refers to the time from the start of one adsorption cycle in the adsorption tower to the completion of final charging and preparation for the next adsorption. The time per pressure swing adsorption cycle is the sum of the times for all decomposition step sequences. As shown in Table 3, if each decomposition step sequence lasts 30 seconds, the entire pressure swing adsorption cycle is 480 seconds (8 minutes). In Table 3, "Adsorption" refers to the adsorption step sequence, "Charge" refers to the final charging step sequence, "Decrease 1 / Add 1" refers to one equalization depressurization / pressurization step sequence, "Decrease 2 / Add 2" refers to two equalization depressurization / pressurization step sequences, "Forward" refers to the forward depressurization step sequence, "Reverse" refers to the reverse depressurization step sequence, and "Purge" refers to the step sequence using forward depressurization gas for purging.

[0095] [Table 3]

[0096] The short cycle pressure swing adsorption method of the present invention will be further described below with reference to specific examples. However, it should be understood that the examples are merely illustrative and that the present invention is not limited thereto.

[0097] Example 1 (specific temperature is 25°C) For the adsorbate N2, the shortest time corresponding to the three adsorbents listed in Table 1 (molecular sieve 1, molecular sieve 2, and activated carbon 1) is less than 15.10 s, and therefore all three adsorbents satisfy the initial selection criteria. Next, molecular sieve 1 (see Table 2), which has the largest product of the slope and the adsorption amount, is selected from the three adsorbents and determined as the target adsorbent.

[0098] Example 2 (specific temperature is 20°C) In this example, the raw material gas had a composition (volume fraction) of 1% nitrogen gas, 8% methane, and 91% hydrogen gas, a pressure of 2 MPa, a temperature of 20°C, and a flow rate of 1000 Nm 3 / h. The objective is to purify and produce hydrogen gas product (hydrogen gas purity: 99.999%) from this raw gas using a pressure swing adsorption process.

[0099] In this example, the purification process was determined as a typical 10-3-4 process, i.e., there were 10 adsorption towers, three towers performed adsorption simultaneously, and four pressure equalization steps were performed, maintaining the yield at 85%. The material balance is shown in Table 4. Using the short-cycle pressure swing adsorption method of the present invention, the adsorption and desorption isotherms of the adsorbents for two adsorbates (nitrogen gas and methane) and the corresponding slope curves were measured. The three adsorbents shown in Table 5 enable room-temperature short-cycle pressure swing adsorption.

[0100] [Table 4]

[0101] [Table 5]

[0102] Based on the results of the above adsorbent measurements, it was possible to produce hydrogen gas by purifying the above feed gas using a single adsorbent, or by grading the adsorbent. For nitrogen gas, the adsorption times of the three adsorbents were all less than 15.10 s (or the slopes were all less than 24), thus satisfying the initial selection criteria. Next, molecular sieve 2, with the largest slope and adsorption capacity, was selected as the target adsorbent. For methane, molecular sieve 1 had an adsorption time less than 15.10 s (or the slope was less than 24), thus selecting molecular sieve 1 as the target adsorbent. Furthermore, because molecular sieve 2 had a larger slope, its corresponding shortest time of 8 s was determined as the shortest time for each decomposition step sequence in the pressure swing adsorption. Therefore, the adsorption period was determined to be approximately 2.7 min. The relationship between the selected adsorbents, adsorption period, and adsorption tower volume is shown in Table 6.

[0103] [Table 6]

[0104] Adsorbent packing scheme 1 uses a grading bed consisting of molecular sieves 2 and 1. Because the molecular weight of methane is larger than that of nitrogen, the adsorbent packing is performed by first passing the feed gas through molecular sieve 1 to adsorb methane, and then through molecular sieve 2 to adsorb nitrogen. While the adsorption cycle is determined by the adsorbent with the steepest initial slope of the adsorption isotherm, the activated carbon bed can fully adsorb methane without transferring it to the molecular sieve bed, thereby maximizing the effectiveness of both adsorbents. A preferred adsorption cycle is 2.7 min. This grading scheme takes into account the adsorption cycle and the adsorbent's adsorption capacity. It maximizes the characteristics of each adsorbent for different adsorbates, achieving an optimal grading process and operating cycle, while also minimizing the volume of the adsorption tower.

[0105] As described above, the innovation of the present invention is that the adsorbent selection method selects target adsorbents for adsorbing one or more target adsorbates, and then performs pressure swing adsorption of the one or more target adsorbates at a specific temperature using the target adsorbents, thereby reducing the amount of adsorbent used and optimizing the pressure swing adsorption cycle, thereby reducing the operating and production costs of pressure swing adsorption.

[0106] Another embodiment of the present invention also provides an adsorbent selection system including: a memory for storing adsorption isotherms of each of a plurality of adsorbents for a target adsorbate; and a processor configured to perform the following operations: acquiring a slope at an initial pressure of the adsorption isotherm of each of the adsorbents for the target adsorbate, where the adsorption isotherm is a curve indicating how the adsorption amount changes depending on the pressure at a specific temperature; acquiring an adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and specific pressure; and selecting a target adsorbent from the plurality of adsorbents for adsorbing the target adsorbate according to the slope and adsorption amount of each of the adsorbents.

[0107] The details and advantages of the adsorbent selection system according to the present invention can be found in the above description of the adsorbent selection method, and therefore will not be described in detail here.

[0108] An embodiment of the present invention also provides a pressure swing adsorption system including: an adsorbent selection system for selecting a target adsorbent for adsorbing one or more target adsorbates; and an adsorption device for performing pressure swing adsorption of the one or more target adsorbates at a specified temperature using the target adsorbent.

[0109] The details and advantages of the pressure swing adsorption system according to the present invention can be found in the above description of the pressure swing adsorption method, and will not be described in detail here.

[0110] An embodiment of the present invention also provides a computer-readable storage medium having stored thereon a computer program that, when executed by a processor, implements the above-described adsorbent selection method and / or the above-described pressure swing adsorption method.

[0111] The above describes in detail some embodiments of the present invention with reference to the drawings. However, the present invention is not limited to the details of the above embodiments. Within the scope of the technical ideas of the present invention, several simple modifications can be made to the technical solutions of the present invention, and all of these simple modifications fall within the protection scope of the present invention.

[0112] It should be noted that the specific technical features described in the above detailed description may be combined in any suitable manner if not contradictory, and in order to avoid unnecessary repetition, the embodiments of the present invention will not specifically describe various possible combination methods.

[0113] Those skilled in the art will understand that all or part of the steps of implementing the methods of the above embodiments can be achieved by a program instructing related hardware. The program is stored in a storage medium containing several instructions for causing a single-chip microcomputer, a chip, or a processor to execute all or part of the steps of the methods described in various embodiments of the present application. Meanwhile, the storage medium includes various media capable of storing program code, such as a USB memory, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, and an optical disk.

[0114] Furthermore, various embodiments of the present invention may be combined in any manner as long as it does not contradict the concept of the present invention, and should be considered as being the same as those disclosed in the present invention.

Claims

1. A method for selecting an adsorbent, comprising the steps of: a step of acquiring a slope of an adsorption isotherm at an initial pressure for each of a plurality of adsorbents for a target adsorbate, the adsorption isotherm being a curve showing the change in adsorption amount depending on pressure at a specific temperature; acquiring an adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and the specific pressure; selecting a target adsorbent for adsorbing the target adsorbate from the plurality of adsorbents according to the gradient and adsorption amount of each adsorbent; The step of selecting a target adsorbent for adsorbing the target adsorbate from among the plurality of adsorbents includes: determining the minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent from the slope of each adsorbent; selecting, based on the determined shortest time, a specific adsorbent from among the plurality of adsorbents whose corresponding shortest time is equal to or shorter than a predetermined time; determining the product of the slope and the adsorption capacity of the particular adsorbent; and selecting the adsorbent corresponding to the largest product as the target adsorbent.

2. determining a minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent, If the slope of the adsorbent is greater than the first slope and less than or equal to the second slope, the shortest time corresponding to the adsorbent is set to be greater than or equal to the first shortest time; If the slope of the adsorbent is greater than the second slope and equal to or less than the third slope, the shortest time corresponding to the adsorbent is set to equal to or greater than the second shortest time; If the slope of the adsorbent is greater than the third slope and less than or equal to the fourth slope, the minimum time corresponding to the adsorbent is set to be greater than or equal to the third minimum time; or when the slope of the adsorbent is greater than the fourth slope and equal to or less than the fifth slope, setting the shortest time corresponding to the adsorbent to equal to or greater than the fourth shortest time; 2. The selection method according to claim 1, wherein the first slope, the second slope, the third slope, the fourth slope, and the fifth slope gradually increase, and the first shortest time, the second shortest time, the third shortest time, and the fourth shortest time gradually increase.

3. 3. The selection method of claim 2, wherein when the first slope is 1, the second slope is 10, the third slope is 20, the fourth slope is 30, and the fifth slope is 50, the first shortest time is 0.05 seconds, the second shortest time is 3 seconds, the third shortest time is 9 seconds, and the fourth shortest time is 24 seconds.

4. determining the minimum time t for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent, [Equation 1] Including, 2. The method of claim 1, wherein T is a predetermined longest step sequence time, the unit of which is s, and k0 is the slope of each of the adsorbents.

5. 5. The method of claim 4, wherein T is 40 or less.

6. determining the shortest time corresponding to the target adsorbent as the adsorption time; 2. The method of claim 1, further comprising: determining an amount of the target adsorbent from an amount of the target adsorbate introduced into the adsorption tower within the adsorption time and an adsorption amount of the target adsorbent.

7. the step of acquiring a slope at an initial pressure of each of the adsorption isotherms of the plurality of adsorbents for the target adsorbate is performed when a predetermined precondition is satisfied; 2. The method of claim 1, wherein the predetermined precondition includes that, at each pressure, the absolute value of the difference between the adsorption amount of each adsorbent in the adsorption isotherm and the adsorption amount of each adsorbent in the desorption isotherm is equal to or less than a predetermined ratio of the adsorption amount of each adsorption isotherm.

8. The predetermined preconditions are: the adsorption amount of the adsorption isotherm of each of the adsorbents for the target adsorbate is equal to or less than the adsorption amount of the desorption isotherm of each of the adsorbents for the target adsorbate at each pressure; 8. The selection method according to claim 7, wherein the desorption isotherm is a curve showing the change in desorption amount depending on pressure at the specific temperature.

9. 2. The method of claim 1, wherein the specific temperature is between 10°C and 40°C.

10. 2. The method of claim 1, wherein the initial pressure is 10 kPa or less.

11. 2. The method of claim 1, wherein the adsorbent is selected from microporous molecular sieves, MOFs, carbon molecular sieves, and silica gel.

12. 1. A pressure swing adsorption process comprising: selecting a target adsorbent for adsorbing one or more target adsorbates by the adsorbent selection method of any one of claims 1 to 11; and performing pressure swing adsorption of the one or more target adsorbates at a specified temperature using the target adsorbent.

13. controlling the pressure swing adsorption process sequence with an integrated rotary valve when the slope of the adsorption isotherm of the target adsorbent at the initial pressure point is greater than a first preset slope and less than or equal to a second preset slope; or 13. The pressure swing adsorption method of claim 12, further comprising the step of controlling a process sequence of the pressure swing adsorption with a sequencing valve when a slope of the adsorption isotherm of the target adsorbent at the initial pressure point is greater than the second preset slope and less than or equal to a third preset slope.

14. If the target adsorbent is a plurality of target adsorbents, the method further comprises grading the plurality of target adsorbents; 13. The pressure swing adsorption method of claim 12, wherein the step of performing pressure swing adsorption of the one or more target adsorbates at a specific temperature using the target adsorbents comprises performing pressure swing adsorption of the one or more target adsorbates at the specific temperature using the plurality of target adsorbents after grading.

15. 15. The pressure swing adsorption method of claim 14, further comprising a step of setting a minimum time for each decomposition step sequence in a cycle period of the pressure swing adsorption based on the slope of the adsorption isotherm of the adsorbent having the largest slope at the initial pressure among the plurality of target adsorbents.

16. 1. A sorbent selection system comprising: a memory for storing adsorption isotherms of each of a plurality of adsorbents for a target adsorbate; an operation of acquiring a slope of an adsorption isotherm of each of the adsorbents for the target adsorbate at an initial pressure, the adsorption isotherm being a curve showing a change in adsorption amount depending on pressure at a specific temperature; an operation of acquiring an adsorption amount of each of the adsorbents for the target adsorbate at the specific temperature and the specific pressure; selecting a target adsorbent for adsorbing the target adsorbate from the plurality of adsorbents according to the gradient and adsorption amount of each adsorbent; a processor configured to execute The operation of selecting a target adsorbent for adsorbing the target adsorbate from the plurality of adsorbents includes: determining the minimum time for each decomposition step sequence in a cycle period of pressure swing adsorption for each adsorbent from the slope of each adsorbent; an operation of selecting, based on the determined shortest time, a specific adsorbent from the plurality of adsorbents whose corresponding shortest time is equal to or shorter than a predetermined time; determining the product of the slope and the adsorption amount of the specific adsorbent; and selecting the adsorbent corresponding to the maximum product as the target adsorbent.

17. 1. A pressure swing adsorption system comprising:

17. The sorbent selection system of claim 16 for selecting a target sorbent for adsorbing one or more target adsorbates; an adsorption device for performing pressure swing adsorption of said one or more target adsorbates at a specified temperature using said target adsorbent.

18. A computer-readable storage medium having a computer program stored therein, the computer program realizing the adsorbent selection method according to any one of claims 1 to 11 when executed by a processor.

19. A computer program is stored, the computer program being configured to: An adsorbent selection system that executes the adsorbent selection method according to any one of claims 1 to 11 is realized, A computer-readable storage medium for causing an adsorption device to perform pressure swing adsorption of the one or more target adsorbates using the target adsorbent at a specified temperature.

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