Process for separating a mixture by means of a gas phase simulated moving bed and a gas phase simulated moving bed for separating a mixture

Abstract

This application relates to a method and apparatus for separating mixtures using a gas-phase simulated moving bed adsorption. The gas-phase simulated moving bed comprises multiple adsorbent beds packed with adsorbent, sequentially divided into a desorption zone, a purification zone, and an adsorption zone. The method includes the following steps: 1) injecting the mixture to be separated upstream of the adsorption zone, whereby the adsorbent in the adsorption zone selectively adsorbs components with stronger adsorption capacity in the mixture under pressure P1; 2) desorbing the components adsorbed on the adsorbent in the desorption zone under pressure P2, where P1 is greater than P2; and 3) a portion of the extracted material flowing downstream of the desorption zone is returned to the upstream of the purification zone. The method and apparatus are advantageous for improving the purity of the target components in the extracted material.

Description

[0001] Cross-references to related applications This application claims priority to the patent application filed by the applicant on March 25, 2025 with the Chinese Patent Office, application number 202510357580.8, entitled "Method for Gas-Phase Simulated Moving Bed Adsorption Separation, Simulated Moving Bed Adsorption Separation Device and Its Application, Method for Separating Mixtures of C4 Alkanes", the contents of which are hereby incorporated herein by reference in their entirety. Technical Field

[0002] This application relates to a method for separating a mixture using a gas-phase simulated moving bed adsorption and a gas-phase simulated moving bed adsorption separation apparatus. Specifically, the gas-phase simulated moving bed adsorption separation apparatus is used to implement the method for separating the mixture using adsorption. Background Technology

[0003] Adsorption separation is highly effective for separating isomers with very small boiling point differences or for separating components with different structural characteristics. For example, adsorption separation can be used to separate xylene from other C8 aromatic isomers (such as m-xylene, o-xylene, and ethylbenzene), and n-alkanes from other structural hydrocarbons (such as n-pentane and isopentane).

[0004] In the early stages of adsorption separation technology development, fixed beds and moving beds were mainly used. However, fixed beds have a relatively low utilization rate of adsorbents and only achieve the separation effect of an equilibrium stage for strongly adsorbed components (the purity of the product is not ideal). In contrast, in moving beds, a large amount of adsorbent circulates and moves, which can easily lead to wear and powdering. Furthermore, it is difficult for the two phases in a moving bed to maintain an ideal flow state, which reduces the separation efficiency.

[0005] To address the aforementioned issues with moving beds, a simulated moving bed process has emerged. In this process, the adsorbent is packed in a fixed bed and remains stationary. By periodically changing the inlet and outlet positions of the various streams of the mobile phase, a countercurrent flow between the stationary and mobile phases is created, thereby improving separation efficiency. For example, the simulated moving bed process can be used to separate xylene from other C8 aromatic isomers (such as m-xylene, o-xylene, and ethylbenzene).

[0006] Existing simulated moving bed adsorption separation processes are mostly applied to liquid-phase separation. Liquid-phase adsorption separation requires the introduction of a desorbent to perform an adsorption-desorption cycle. Specifically, the adsorbent contacts the material to be separated, adsorbing the target component and producing a raffinate containing the unadsorbed component. The desorbent displaces the target component from the adsorbent, producing an extract containing the target component, while the adsorbent is recycled. Then, distillation can be used to separate the desorbent from the target component in the extract, and distillation can be used to separate the desorbent from other components in the raffinate. The resulting desorbent is usually recycled. The distillation process for separating the desorbent requires significant energy consumption.

[0007] In addition, adsorption separation can also employ pressure swing adsorption (PSA), which is currently widely used for separating gas mixtures such as air. PSA typically involves multiple adsorption columns, each relatively independent. Although there are steps that directly connect two adsorption columns operating at different times, the purpose is to equalize the pressure, ensuring that the adsorption front never extends beyond the range of a single adsorption column. Therefore, the methods for controlling the purity and yield of the separated components using PSA are relatively limited.

[0008] Therefore, there is still a need to develop a new adsorption separation method that can provide the desired separation efficiency and target component purity, and overcome the problem of high energy consumption and cost associated with additional distillation separation of desorbents. Summary of the Invention

[0009] The purpose of this invention is to provide a method for separating mixtures using a gas-phase simulated moving bed adsorption and a gas-phase simulated moving bed adsorption and separation device.

[0010] In a first aspect, the present invention relates to a method for separating mixtures by adsorption using a gas-phase simulated moving bed, the gas-phase simulated moving bed comprising multiple adsorbent beds packed with adsorbent and sequentially divided into desorption zones, purification zones, and adsorption zones, wherein the method comprises the following steps: 1) The mixture to be separated is injected from the upstream of the adsorption zone, and the adsorbent in the adsorption zone selectively adsorbs the components with stronger adsorption capacity in the mixture under pressure P1; 2) The components adsorbed on the adsorbent undergo desorption in the desorption zone under pressure P2, where P1 is greater than P2; and 3) A portion of the extracted material flowing out downstream of the desorption zone is returned to the upstream of the purification zone; Preferably, the extraction reflux coefficient ε = Q / (V' / t × 3600) is 0.8-1.8, where Q is the volumetric flow rate of the extracted reflux material, in m³ / s. 3 / h, V' is the volume of a single adsorbent bed, in m³. 3t is the step time, in seconds.

[0011] In a second aspect, the present invention relates to a method for improving the purity of a target component in the extract of a gas-phase simulated moving bed, comprising the steps described in the first aspect.

[0012] Thirdly, the present invention relates to a gas-phase simulated moving bed adsorption separation apparatus. Preferably, the gas-phase simulated moving bed adsorption separation apparatus is used to implement the method according to the first aspect and / or the second aspect.

[0013] Compared to liquid-phase simulated moving bed adsorption separation processes, the gas-phase simulated moving bed adsorption separation method and apparatus according to the present invention can eliminate the need for desorbents, thereby saving the operation of introducing desorbents and subsequent distillation separation of desorbents, as well as the associated energy and costs. Simultaneously, the method and apparatus according to the present invention can achieve ideal separation efficiency and target component purity. Compared to pressure swing adsorption separation processes, the method and apparatus according to the present invention connects individual adsorbent beds in series through pipelines to form a ring arrangement for continuous adsorption separation, resulting in more efficient utilization of the adsorbent and better control to achieve ideal separation efficiency and target component purity. Furthermore, by controlling the extraction reflux coefficient, the purity of the target component in the extracted material of the gas-phase simulated moving bed can be improved.

[0014] Brief description of the attached figures Figure 1 This is a schematic diagram of the pipeline connections of the gas-phase simulated moving bed adsorption separation device according to Embodiment 2 of the present invention.

[0015] Figure 2 This is a schematic diagram of the entry and exit positions of each material in the method for separating a mixture using a liquid-phase simulated moving bed adsorption, which is not the present invention, as described in Comparative Example 1.

[0016] Figure 3 This is a schematic diagram of the pipeline connections and valve opening / closing status of a gas-phase simulated moving bed adsorption separation device during a certain step time according to Embodiment 1 of the present invention.

[0017] Explanation of reference numerals in the attached figures F: Mixture to be separated (raw material) B: Recirculated material E: Extracted material R: Residual material; C1: Rinse solution 1; C3: Rinse solution 2; D: Desorbent C-1 to C-6: Valves on the connecting pipelines between two adjacent adsorbent beds F-1 to F-6: Valves on the pipelines used to introduce raw materials, which are connected to the connecting pipeline between two adjacent adsorbent beds. E-1 to E-6: Valves on pipelines connected to the connecting pipeline between two adjacent adsorbent beds for leading out extracted material (or depressurized desorbed material). B-1 to B-6: Valves on pipelines connected to the connecting lines between two adjacent adsorbent beds, used to introduce the extracted reflux material into the upstream of the purification zone. R-1 to R-6: Valves on pipelines connected to the connecting lines between two adjacent adsorbent beds, used for removing residual material and pressurizing the adsorption column. V-1 to V-6: Valves on pipelines connected to the connecting pipeline between two adjacent adsorbent beds for leading out the desorbed material. Detailed Implementation

[0018] The present application will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present application, and do not limit the present invention in any way.

[0019] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0020] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0021] The expressions “comprising” or “including” in this document should be interpreted as including all specifically mentioned features as well as optional, additional, or unspecified features. As used herein, the use of the term “comprising” also discloses schemes in which no other features besides the specifically mentioned features are present, such as expressions “consistently composed of” and “composed of”.

[0022] In a first aspect, the present invention relates to a method for separating mixtures by adsorption using a gas-phase simulated moving bed, the gas-phase simulated moving bed comprising multiple adsorbent beds packed with adsorbent and sequentially divided into desorption zones, purification zones, and adsorption zones, wherein the method comprises the following steps: 1) The mixture to be separated is injected from the upstream of the adsorption zone, and the adsorbent in the adsorption zone selectively adsorbs the components with stronger adsorption capacity in the mixture under pressure P1; 2) The components adsorbed on the adsorbent undergo desorption in the desorption zone under pressure P2, where P1 is greater than P2; and 3) A portion of the extracted material flowing out downstream of the desorption zone is returned to the upstream of the purification zone; Preferably, the extraction reflux coefficient ε = Q / (V' / t × 3600) is 0.8-1.8, where Q is the volumetric flow rate of the extracted reflux material, in m³ / s. 3 / h, V' is the volume of a single adsorbent bed, in m³. 3 t is the step time, in seconds.

[0023] Preferably, the extraction reflux coefficient ε is 1.0-1.7. For example, the extraction reflux coefficient ε is 0.80, 0.85, 0.90, 0.92, 0.95, 0.98, 1.00, 1.02, 1.05, 1.08, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, or a value within a range consisting of any two of the above values ​​or one of the above values ​​and one endpoint of one of the above ranges or one endpoint of one of the above ranges and one endpoint of another of the above ranges.

[0024] According to the present invention, multiple adsorbent beds in the "gas-phase simulated moving bed" are connected in series by pipelines to form a ring arrangement, and they are sequentially divided into desorption zone, purification zone, and adsorption zone. For example, a gas-phase simulated moving bed has N adsorbent beds, denoted as adsorbent bed 1, 2, 3, ..., N. Each adsorbent bed has two material inlets and outlets (e.g., a first inlet and outlet at the top and a second inlet and outlet at the bottom). The second inlet and outlet of adsorbent bed 1 is connected to the first inlet and outlet of adsorbent bed 2 by pipelines, the second inlet and outlet of adsorbent bed 2 is connected to the first inlet and outlet of adsorbent bed 3 by pipelines, and so on, with the second inlet and outlet of adsorbent bed N connected to the first inlet and outlet of adsorbent bed 1 by pipelines. In the "gas-phase simulated moving bed," the mixture to be separated exists in gaseous form, and separation is achieved by utilizing the different adsorption capacities of the components in the mixture with the adsorbents in the bed, based on the adsorption-desorption principle. After each step time, the inflow and outflow positions of each material (including the mixture to be separated, the extracted material, the residual material, and the extracted reflux material) move one adsorbent bed along the flow direction of the mixture to be separated (raw material).

[0025] According to the present invention, the expression "selective adsorption of the component with stronger adsorption capacity in the mixture" means that the content of the component with stronger adsorption capacity adsorbed on the adsorbent bed of the adsorption zone accounts for a majority, for example, greater than 50 wt.%, preferably greater than 80 wt.%, and most preferably close to 100 wt.%, relative to the total weight of all components adsorbed on the adsorbent bed of the adsorption zone.

[0026] Preferably, each adsorbent bed is contained within an adsorption column. For example, the desired adsorbent is filled (preferably as full as possible) into the adsorption column. When substantially full, the volume of the adsorbent bed is substantially the same as the volume of the adsorption column, and V' can be considered as the volume of a single adsorption column.

[0027] The extraction reflux coefficient within the specified range can effectively improve the purity of the target component in the extracted material. The "target component" refers to a component with a weight percentage greater than 50 wt.%, preferably greater than 80 wt.%, and most preferably close to 100 wt.% in the extracted material.

[0028] Preferably, the method according to the invention does not introduce a desorbent. The separation of the mixture according to the invention utilizes the different pressures of the adsorption and desorption zones, thus eliminating the need for a desorbent and saving the use of a desorbent and subsequent operations and equipment related to distillation and purification of the desorbent. According to the invention, the desorbent has a conventional meaning in the chemical engineering field, particularly in adsorption separation processes; it desorbs or desorbs the adsorbed components from the adsorbent, for example, through good compatibility (e.g., solubility) with the adsorbed components.

[0029] Preferably, the gas-phase simulated moving bed further includes at least one adsorbent bed (preferably one adsorbent bed) divided into an aeration and pressurization zone, and the adsorbent beds in the gas-phase simulated moving bed are connected in series by pipelines to form a ring arrangement, and the adsorbent beds are sequentially divided into the desorption zone, purification zone, adsorption zone and aeration and pressurization zone.

[0030] Preferably, the adsorbent bed in the pressurization zone is connected to a pipeline for removing residual material. This means that a section of pipeline can be used to remove residual material or to pressurize the pressurization zone, depending on whether the bed connected to it is in the adsorption zone or the pressurization zone. When the bed connected to a pipeline is in the adsorption zone, this section of pipeline is used to remove residual material; when the bed connected to a pipeline is in the pressurization zone, this section of pipeline is used to pressurize the pressurization zone.

[0031] Preferably, during the operation of the gas-phase simulated moving bed, adjacent adsorbent beds in the purification zone and the adsorption zone are interconnected, so the pressure in the purification zone and the adsorption zone is basically the same.

[0032] Preferably, during the operation of the gas-phase simulated moving bed, the adsorbent beds in the purification zone and adsorption zone are not connected to the adsorbent beds in the desorption zone or the gas-pressurization zone, and the adsorbent beds in the desorption zone and the gas-pressurization zone are also not connected. Therefore, the pressure in the purification zone and adsorption zone may be different from the pressure in the desorption zone or the gas-pressurization zone.

[0033] According to the present invention, whether adjacent adsorbent beds are connected can be controlled by installing at least one valve on the pipeline connecting them.

[0034] Preferably, the pressure of the pipeline used to draw out the extracted material is lower than the pressure of the pipeline used to introduce the raw material.

[0035] Preferably, the pressure of the pipeline used to remove residual material is lower than the pressure of the pipeline used to introduce raw material.

[0036] Preferably, the pressure of the pipeline used to introduce the extracted reflux material into the upstream of the purification zone is higher than the pressure of the pipeline used to introduce the raw material.

[0037] The pressure settings in the aforementioned pipelines and the connectivity (whether or not) between the bed layers in each zone facilitate the entry and exit of the mixture into the gas-phase simulated moving bed and the effective adsorption and separation of the mixture to be separated (raw material) within it. Furthermore, the pressure settings in the aforementioned pipelines allow the pressure P1 in the adsorption zone to be greater than the pressure P2 in the desorption zone.

[0038] Preferably, the desorption zone includes a vacuum desorption zone and a depressurization desorption zone. By incorporating a vacuum desorption zone within the desorption zone, the throughput of the gas-phase simulated moving bed can be increased while achieving the same effect (e.g., extracting the purity of the target component from the material). Preferably, the vacuum desorption zone and the depressurization desorption zone are not connected.

[0039] According to the present invention, the term "pressure reduction desorption zone" is used to distinguish it from "vacuum desorption zone". Preferably, the pressure in the pressure reduction desorption zone is lower than the pressure in the adsorption zone and the purification zone, but higher than the pressure in the vacuum desorption zone.

[0040] Accordingly, the extracted material includes evacuation desorption material and depressurization desorption material. Preferably, the pressure in the pipeline used to lead out the extracted material is lower than the pressure in the pipeline used to introduce the raw material at the position after the evacuation desorption material and the depressurization desorption material merge to form the extracted material, as well as the pressure in the two pipelines before the merging.

[0041] When the extracted material includes evacuation desorption material and depressurization desorption material, the flow rate of the extracted material is equal to the flow rate of the evacuation desorption material plus the flow rate of the depressurization desorption material minus the flow rate of the extracted return material.

[0042] Preferably, after the evacuated desorbed material and the depressurized desorbed material merge to form the extracted material, a portion of the extracted material is returned to the upstream of the purification zone as extracted reflux material, and the unreturned extracted material flows out of the gas phase simulated moving bed.

[0043] Preferably, the pressure of the pipeline used to draw out the evacuated desorbed material is lower than the pressure of the pipeline used to draw out the depressurized desorbed material, and the pressure of the pipeline used to draw out the evacuated desorbed material is not higher than 0.06 MPa, preferably 0.01 MPa to 0.06 MPa.

[0044] Preferably, the pipeline for leading out the evacuated desorbed material, the pipeline for leading out the depressurized desorbed material, the pipeline for leading out the residual material and pressurizing the gas-pressurized zone (when the gas-phase simulated moving bed includes the gas-pressurized zone), the pipeline for introducing the extracted reflux material into the upstream of the purification zone, and the pipeline for introducing the raw material are respectively connected to the connecting pipeline between each of the two adjacent adsorbent beds and are respectively equipped with valves.

[0045] Preferably, the pipeline for introducing the extracted reflux material into the upstream of the purification zone is equipped with a pressurization device and / or a flow control device, and / or is connected to a pipeline for leading out the extracted material.

[0046] During the operation of the gas-phase simulated moving bed, the mixture (raw material) to be separated flows into the gas-phase simulated moving bed from the upstream of the adsorption zone through a pipeline for introducing the raw material. Components with stronger adsorption capacity are selectively (preferably or in larger quantities) adsorbed onto the adsorbent bed in the adsorption zone under pressure P1. Components that are not adsorbed flow out of the gas-phase simulated moving bed from the downstream of the adsorption zone through a pipeline for removing the raffinate.

[0047] During the operation of the gas-phase simulated moving bed, the extracted reflux material flows back into the gas-phase simulated moving bed from the upstream of the purification zone through a pipeline used to introduce the extracted reflux material into the upstream of the purification zone, thus flushing the adsorbent bed that has adsorbed a large number of components with strong adsorption capacity.

[0048] During the operation of the gas-phase simulated moving bed, at a pressure P2 less than P1, the components adsorbed on the adsorbent bed in the desorption zone desorb and flow out of the gas-phase simulated moving bed downstream of the desorption zone through a pipeline for extracting the extracted material. When the desorption zone includes a vacuum desorption zone and a depressurization desorption zone, the components adsorbed on the adsorbent bed desorb and flow from the downstream of the vacuum desorption zone into a pipeline for extracting the vacuum desorbed material, and from the downstream of the depressurization desorption zone into a pipeline for extracting the depressurization desorbed material, respectively. The two pipelines are then connected, causing the vacuum desorbed material and the depressurization desorbed material to converge and form the extracted material. A portion of this extracted material is returned to the upstream of the purification zone as reflux material, and the remainder flows out of the gas-phase simulated moving bed.

[0049] Preferably, during the operation of the gas-phase simulated moving bed, the valves on the pipeline downstream of the evacuation-desorption zone for leading out the evacuation-desorbed material, the valves on the pipeline downstream of the depressurization-desorption zone for leading out the depressurization-desorbed material, the valves on the pipeline downstream of the evacuation zone for leading out the evacuation-residue material, the valves on the pipeline upstream of the purification zone for introducing the extracted reflux material into the purification zone, the valves on the pipeline upstream of the adsorption zone for introducing raw materials, and the valves on the pipeline for pressurizing the gas-pressurization zone (when the gas-phase simulated moving bed includes the gas-pressurization zone) are in the open state, and the other valves are in the closed state.

[0050] In some implementation schemes, such as Figure 3 As shown, a gas-phase simulated moving bed consisting of six adsorption columns is used to separate the mixture to be separated. The six adsorption columns are designated as Column 1, Column 2, Column 3, Column 4, Column 5, and Column 6, respectively. They are connected by connecting pipelines, each equipped with a valve, and the six valves are designated as C-1 to C-6. Six valves on the pipelines connecting to the connecting pipelines between two adjacent adsorbent beds for introducing raw materials are designated as F-1 to F-6. Six valves on the pipelines connecting to the connecting pipelines between two adjacent adsorbent beds for discharging depressurized desorbed material are designated as E-1 to E-6. The six valves on the pipeline connected to the pipeline for leading out the desorbed material are designated as V-1 to V-6. The six valves on the pipeline connected to the connecting pipeline between two adjacent adsorbent beds for introducing the extracted reflux material into the upstream of the purification zone are designated as B-1 to B-6. The six valves on the pipeline connected to the connecting pipeline between two adjacent adsorbent beds for leading out the residual material and for pressurizing the adsorption column are designated as R-1 to R-6. A flow control device and a pressurization device are installed on the pipeline for introducing the extracted reflux material into the upstream of the purification zone, and a vacuum pump is installed on the pipeline for leading out the desorbed material.

[0051] In a step time, such as Figure 3 As shown, column 1 is located in the vacuum desorption zone, column 2 in the depressurization desorption zone, column 3 in the purification zone, columns 4 and 5 in the adsorption zone, and column 6 in the gas-pressurization zone. Valves C-3 and C-4 connecting adjacent adsorption columns are open, while valves C-1, C-2, C-5, and C-6 are closed. Valves V-1 (for discharging vacuum desorbed material), E-2 (for discharging depressurization desorbed material), B-3 (for introducing refluxed material into the upstream of the purification zone), F-4 (for introducing raw material), R-5 (for discharging residual material), and R-6 (for pressurizing the adsorption column) are open. All other valves are closed.

[0052] In the next step time interval, column 2 is located in the vacuum desorption zone, column 3 in the depressurization desorption zone, column 4 in the purification zone, columns 5 and 6 in the adsorption zone, and column 1 in the gas-pressurization zone. Valves C-4 and C-5 connecting adjacent adsorption columns are open, while valves C-1, C-2, C-3, and C-6 are closed. Valves V-2 (for discharging evacuated desorbed material), E-3 (for discharging depressurized desorbed material), B-4 (for introducing reflux material into the upstream of the purification zone), F-5 (for introducing raw material), R-6 (for discharging residual material), and R-1 (for pressurizing the adsorption column) are open; all other valves are closed. This process continues for six steps, after which the gas-phase simulated moving bed returns to its initial state, completing one cycle.

[0053] According to the present invention, the volumetric flow rate Q of the extracted reflux material, the volume V' of a single adsorbent bed, and the stepping time t can be appropriately adjusted according to factors such as the structure of the gas-phase simulated moving bed, the bed connection method, and the type of mixture to be separated.

[0054] For example, the volumetric flow rate Q of the extracted reflux material can be 80-300 m³. 3 / h, or 100-250 m 3 / h.

[0055] For example, the volume V' of a single adsorbent bed can be 1-10 m³. 3 or 3-8 m 3 .

[0056] For example, the step time t can be 50-300 s or 100-200 s.

[0057] Preferably, the mixture comprises at least two C2-C4 alkanes and / or olefins. For example, the C2-C4 alkanes may be ethane, n-propane, isopropane, n-butane, isobutane, tert-butane, or mixtures thereof. For example, the C2-C4 olefins may be ethylene, propylene, n-butene, isobutene, or mixtures thereof.

[0058] More preferably, the mixture comprises n-butane and isobutane. As one embodiment, the mixture is a mixture of n-butane and isobutane.

[0059] Preferably, the adsorption separation of the mixture is carried out at a temperature of 20°C to 220°C, more preferably 80°C to 200°C, and even more preferably 120°C to 200°C. This means that the gas-phase simulated moving bed operates at such temperatures.

[0060] Preferably, the pressure of the pipeline used to introduce the raw material is 0.2 MPa to 3 MPa, more preferably 0.5 MPa to 2.5 MPa, and even more preferably 0.8 MPa to 2.0 MPa.

[0061] Preferably, the pressure of the pipeline used to extract residual material is 0.02 MPa to 0.2 MPa lower than the pressure of the pipeline used to introduce raw material, more preferably 0.03 MPa to 0.1 MPa.

[0062] Preferably, the pressure of the pipeline used to draw out the extracted material is 0.08 MPa to 0.5 MPa, more preferably 0.1 MPa to 0.3 MPa. When the desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, the pressure of the pipeline used to draw out the extracted material refers to the pressure at the position where the vacuum desorbed material and the pressure reduction desorbed material converge to form the extracted material.

[0063] Preferably, the desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, and the pressure of the pipeline for leading out the vacuum desorbed material is 0.01 MPa to 0.06 MPa.

[0064] Preferably, the pressure of the pipeline used to introduce the extracted reflux material into the upstream of the purification zone is 0.02 MPa to 0.2 MPa higher than the pressure of the pipeline used to introduce the raw material, more preferably 0.02 MPa to 0.1 MPa.

[0065] Preferably, the step time is 20 s to 500 s, more preferably 50 s to 200 s.

[0066] The adsorption separation method according to the present invention eliminates the need for a desorbent, thereby saving the operation of using a desorbent and subsequent distillation to separate the desorbent, as well as the associated energy consumption and costs. Furthermore, the method according to the present invention achieves ideal separation efficiency and the purity of the target component. In addition, the method according to the present invention allows for continuous adsorption separation of the mixture to be separated, making fuller use of the adsorbent and allowing for better control, thus achieving ideal separation efficiency and the purity of the target component.

[0067] Hydrocarbons are known to typically require a certain purity level to be used as raw materials in industrial production. For example, basic industrial-grade n-butane has a purity of 98%, while premium industrial-grade n-butane has a purity of 99.5%. By controlling the extraction reflux coefficient, the purity of the target component in the extracted material of a gas-phase simulated moving bed can be improved, thereby obtaining hydrocarbons with the desired purity. For example, by controlling the extraction reflux coefficient within the range of this invention, when the mixture to be separated consists of n-butane and isobutane, the n-butane, as the target component of the extracted material, can achieve a purity of over 99.5%.

[0068] Preferably, by controlling the extraction reflux coefficient, a high recovery rate of the target component can be ensured while simultaneously improving the purity of the extracted material. For example, when the mixture to be separated consists of n-butane and isobutane, the n-butane, as the target component of the extracted material, can achieve a purity of over 99.5% and a recovery rate of over 80%, preferably over 85%, or even over 90%. According to the present invention, the recovery rate of the target component = mass (or mass flow rate) of the target component in the extracted material / mass (or mass flow rate) of the target component in the mixture to be separated (raw material) * 100%.

[0069] Secondly, the present invention relates to a method for improving the purity of a target component in the extract of a gas-phase simulated moving bed. The method according to the second aspect of the invention is implemented by the method steps described above according to the first aspect of the invention.

[0070] As described above, the “target component” refers to a component that accounts for more than 50 wt.% of the extracted material by weight, preferably more than 80 wt.%, and most preferably close to 100 wt.%.

[0071] Thirdly, the present invention relates to a gas-phase simulated moving bed adsorption separation device, wherein the simulated moving bed comprises multiple adsorbent beds arranged in a ring by being connected in series end to end by pipelines, and the adsorbent beds are sequentially divided into a desorption zone, a purification zone, an adsorption zone, and preferably a gas-pressurization zone; a valve is provided on the connecting pipeline between two adjacent adsorbent beds; Each of the aforementioned connecting lines is respectively connected to a line for introducing raw materials, a line for withdrawing extracted materials, a line for withdrawing residual materials and pressurizing the gas charging process, and a line for introducing extracted reflux materials upstream of the purification zone; and the line for introducing extracted reflux materials upstream of the purification zone is connected to the line for withdrawing extracted materials. The pipeline used to introduce the extracted reflux material into the upstream of the purification zone is preferably equipped with a pressurization device and / or a flow control device.

[0072] Preferably, the adsorbent bed in the pressurization zone is connected to a pipeline for extracting residual material.

[0073] According to the present invention, the valve on the connecting pipeline between two adjacent adsorbent beds controls whether the two adjacent adsorbent beds are connected by opening and closing.

[0074] Preferably, the desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, and the pipeline for extracting the material includes a pipeline for leading out the vacuum desorbed material and a pipeline for leading out the pressure reduction desorbed material connected in parallel. One end of these two pipelines is connected to the connecting pipeline between the adsorbent beds, and their other ends are connected to allow the vacuum desorbed material and the pressure reduction desorbed material to come together to form the extracted material.

[0075] Preferably, the pipeline used to draw out the desorbed material is equipped with a vacuum pump.

[0076] Preferably, the connecting pipeline between two adjacent adsorbent beds is divided into two sides by a valve. The pipeline for introducing raw materials and the pipeline for introducing the extracted reflux material upstream of the purification zone are connected to the connecting pipeline on one side of the valve, while the pipeline for discharging the extracted material and the pipeline for discharging the residual material and pressurizing the gas-pressurization process are connected to the connecting pipeline on the other side of the valve. When the desorption zone includes a vacuum desorption zone and a depressurization desorption zone, the pipeline for discharging the extracted material includes a pipeline for discharging the vacuum desorbed material and a pipeline for discharging the depressurized desorbed material.

[0077] Preferably, the gas-phase simulated moving bed has at least five adsorbent beds, of which at least two adsorbent beds are used for the adsorption zone. For example, the gas-phase simulated moving bed can have 5 to 12, such as 5, 6, 7, 8, 9, 10, 11, or 12 adsorbent beds. Preferably, the adsorbent beds are included in an adsorption column.

[0078] According to the present invention, the volume of the adsorption column can be appropriately adjusted according to factors such as the structure of the gas-phase simulated moving bed, the connection method of the adsorption column, and the type of mixture to be separated.

[0079] For example, the volume of each adsorption column is 0.1 m³. 3 Up to 200 m 3 , or 0.1 m 3 Up to 100 m 3 , or 1 m 3 up to 50 m 3 , or 1 m 3 Up to 20 m 3 .

[0080] Preferably, the number of adsorbent beds in the adsorption zone accounts for no less than one-third of the total number of adsorbent beds in the gas-phase simulated moving bed.

[0081] In one embodiment, the gas-phase simulated moving bed has six adsorbent beds arranged in a ring by being connected end to end by pipelines, wherein one adsorbent bed is used for a vacuum desorption zone, one adsorbent bed is used for a depressurization desorption zone, one adsorbent bed is used for a purification zone, two adsorbent beds are used for an adsorption zone, and one adsorbent bed is used for a gas-pressurization zone.

[0082] In one embodiment, the gas-phase simulated moving bed has six adsorbent beds arranged in a ring by being connected end to end by pipelines, wherein one adsorbent bed is used for the desorption zone, two adsorbent beds are used for the purification zone, two adsorbent beds are used for the adsorption zone and one adsorbent bed is used for the gas-pressurization zone.

[0083] In some implementation schemes, such as Figure 1 As shown, the gas-phase simulated moving bed consists of six adsorption columns, designated as column 1, column 2, column 3, column 4, column 5, and column 6. Each column is connected by a connecting pipeline equipped with a valve, designated as C-1 to C-6. Six valves on the pipeline connecting to the adjacent adsorbent bed for introducing raw materials are designated as F-1 to F-6. Six valves on the pipeline connecting to the adjacent adsorbent bed for extracting the extracted material are designated as E-1 to E-6. Six valves on the pipeline connecting to the adjacent adsorbent bed for introducing the extracted reflux material into the upstream of the purification zone are designated as B-1 to B-6. Six valves on the pipeline connecting to the adjacent adsorbent bed for extracting residual material and pressurizing the adsorption columns are designated as R-1 to R-6. A flow control device and a pressurization device are installed on the pipeline for introducing the extracted reflux material into the upstream of the purification zone.

[0084] During operation, for example, within one step time, column 1 is located in the desorption zone, columns 2 and 3 are located in the purification zone, columns 4 and 5 are located in the adsorption zone, and column 6 is located in the gas-pressurization zone. Valves C-2, C-3, and C-4 on the connecting pipeline between two adjacent adsorption columns are in the open state, while valves C-1, C-5, and C-6 are in the closed state. Valves E-1 on the pipeline for drawing out the extracted material, valve B-2 on the pipeline for introducing the extracted reflux material upstream of the purification zone, valve F-4 on the pipeline for introducing the raw material, valve R-5 on the pipeline for drawing out the residual material, and valve R-6 on the pipeline for pressurizing the adsorption column are in the open state, while all other valves are in the closed state.

[0085] In the next step time, column 2 is in the desorption zone, columns 3 and 4 are in the purification zone, columns 5 and 6 are in the adsorption zone, and column 1 is in the gas-pressurization zone. Valves C-3, C-4, and C-5 on the connecting pipeline between adjacent adsorption columns are open, while valves C-1, C-2, and C-6 are closed. Valves E-2 on the pipeline for drawing out the extracted material, B-3 on the pipeline for introducing the extracted reflux material upstream of the purification zone, F-5 on the pipeline for introducing the raw material, R-6 on the pipeline for drawing out the residual material, and R-1 on the pipeline for pressurizing the adsorption column are open; all other valves are closed. This process continues for six steps, after which the gas-phase simulated moving bed returns to its initial state, completing one cycle.

[0086] The adsorbent used in the gas-phase simulated moving bed according to the present invention can be any conventional adsorbent used in the chemical industry for adsorbing and separating liquid or gas mixtures, provided that the adsorbent's adsorption capacity for the target component is higher than that for other components in the mixture to be separated.

[0087] For example, the adsorbent may be a molecular sieve (e.g., 5A molecular sieve), silica gel, alumina, activated carbon, or a combination thereof.

[0088] According to the present invention, the adsorbent can be any conventional shape that an adsorbent can have. For example, the adsorbent can be spherical, cylindrical, and / or irregular in shape.

[0089] According to the present invention, the adsorbent can have a particle size of any commonly used adsorbent in the chemical industry. For example, the particle size of the adsorbent can be from 0.1 mm to 5 mm, such as from 0.1 mm to 1 mm. The particle size of the adsorbent can be measured using any conventional methods and instruments in the chemical industry. For example, the particle size of the adsorbent can be measured using sieving.

[0090] Preferably, the apparatus according to the third aspect of the invention is used to implement the method according to the first and / or second aspects of the invention. Preferably, the apparatus according to the third aspect of the invention does not include an inlet or line for introducing the desorbent.

[0091] This application relates to the following technical solutions: Project [1], a method for adsorption separation in a gas-phase simulated moving bed, wherein the method includes: injecting an adsorption raw material containing components with different adsorption capacities into a simulated moving bed, adsorbing the preferred adsorption component under a higher pressure, desorbing the preferred adsorption component under a lower pressure, taking out the extracted material enriched with the preferred adsorption component and the raffinate, and returning part of the extracted material as the extracted reflux material to the simulated moving bed. The simulated moving bed includes N adsorption columns, where N≥5; along the material flow direction within the adsorption columns, the adsorption column between the extraction return material injection position and the adsorption raw material injection position constitutes the purification zone, and the adsorption column between the adsorption raw material injection position and the residual material extraction position constitutes the adsorption zone; within the purification zone and the adsorption zone, the outlet of the upstream adsorption column is connected to the inlet of the adjacent downstream adsorption column, so that the material in the adsorption column flows sequentially through each adsorption column in the purification zone and the adsorption zone, and the remaining adsorption columns are not connected to each other. After each step time, the injection or removal position of each of the above materials moves one adsorption column along the material flow direction within the adsorption column.

[0092] Project [2], according to the method described in Project [1], wherein no desorbent is introduced during the desorption process; Preferably, along the material flow direction inside the adsorption column, the materials entering and exiting the simulated moving bed are, in sequence, the extracted material, the extracted reflux material, the adsorbed raw material, and the raffinate material. The pressure in the extraction pipeline is lower than the pressure in the adsorption feedstock pipeline, causing the preferentially adsorbed components in the adsorption column to desorb.

[0093] Project [3], the method according to Project [1] or [2], wherein the extracted material includes vacuum desorption material and pressure reduction desorption material; Preferably, the pipeline pressure of the evacuated desorbed material is lower than the pipeline pressure of the depressurized desorbed material, and the pipeline pressure of the evacuated desorbed material is not higher than 0.06 MPa, preferably 0.01-0.06 MPa.

[0094] Project [4], according to any one of the methods described in Projects [1]-[3], the pipeline pressure for extracting reflux material is higher than the pipeline pressure for adsorbing raw material; Preferably, the relationship between the volumetric flow rate Q of the extracted reflux material, the volume V of a single adsorption column, and the step time t satisfies the following condition: the value of Q / (V / t×3600) is 0.8-2.5, where Q is in m3 / h, V is in m3, and t is in s.

[0095] Project [5], the method according to any one of Projects [1]-[4], wherein the adsorption zone contains at least 2 adsorption columns, preferably, the number of adsorption columns in the adsorption zone accounts for no less than one-third of the total number of adsorption columns.

[0096] Project [6], a simulated moving bed adsorption separation device, characterized in that the device comprises: N adsorption columns connected in series by connecting pipelines, wherein N≥5; Along the material flow direction, the outlet of the nth adsorption column is connected to the inlet of the (n+1)th adsorption column via a connecting pipeline, and the outlet of the Nth adsorption column is connected to the inlet of the 1st adsorption column via a connecting pipeline; an isolation valve is installed on the connecting pipeline between two adjacent adsorption columns, and the connection and disconnection between adjacent adsorption columns are controlled by opening and closing the isolation valve; 1≤n<N. Each connecting line is connected to the raw material line, the extracted material line, the residual material line, and the extracted reflux material line, respectively, for injecting or removing material into the adsorption column; wherein, the extracted reflux material line is connected to the extracted material line, for returning at least a portion of the extracted material to the adsorption column.

[0097] Item [7], the apparatus according to Item [6], wherein a booster device is provided upstream of the extraction return material pipeline; Preferably, a flow control device is also provided upstream of the extraction and return material pipeline.

[0098] Item [8], the apparatus according to Item [6] or [7], wherein the extraction material pipeline includes a parallel vacuum desorption material pipeline and a pressure reduction desorption material pipeline, the upstream of the above pipelines being connected to the connecting pipeline between the adsorption columns respectively; Preferably, the desorption material pipeline is equipped with a vacuum pumping device.

[0099] Item [9], the apparatus according to Item [7] or [8], wherein the connecting pipeline between two adjacent adsorption columns is divided into two sections by a shut-off valve, the raw material pipeline and the extraction return material pipeline are connected to the connecting pipeline at one side of the shut-off valve, and the extraction material pipeline and the residual material pipeline are connected to the connecting pipeline at the other side of the shut-off valve.

[0100] The method of gas phase simulated moving bed adsorption separation according to any one of the items [1]-[6] or the application of the simulated moving bed adsorption separation device according to any one of the items [7]-[9] in the separation of gas phase mixtures.

[0101] Project

[11] , a method for separating a mixture of C4 alkanes, characterized in that the gas-phase simulated moving bed adsorption separation method described in any one of Projects [1]-[6] or the simulated moving bed adsorption separation device described in any one of Projects [7]-[9] is used for adsorption separation; The adsorption raw materials include n-butane and isobutane; Preferably, the adsorption separation is carried out under gas phase conditions; preferably, the temperature of the adsorption separation is from room temperature to 220°C, and more preferably 80-200°C. Preferably, the pipeline pressure for adsorbing raw materials is 0.2-3 MPa; Preferably, the pipeline pressure of the raffinate is 0.05-0.2 MPa lower than the adsorption feedstock pipeline pressure; Preferably, the pipeline pressure for extracting material is 0.1-0.5 MPa; Preferably, the pipeline pressure for evacuating and desorbing the material is 0.01-0.06 MPa; Preferably, the pressure of the pipeline for extracting the reflux material is 0.02-0.2 MPa higher than the pressure of the adsorption raw material pipeline; Preferably, the volume of a single adsorption column is 0.1-200 m³. 3 ; Preferably, the step time is 20-500s. Example

[0102] The following embodiments will further illustrate the method of this application, but do not limit the scope of this application. In the following embodiments and comparative examples, unless otherwise specified, the experimental instruments and raw materials involved are commercially available products.

[0103] The adsorbents used in the following examples and comparative examples were spherical particles with a particle size ranging from 0.3 mm to 0.8 mm as measured by sieving, and were pre-activated by calcination at 500°C for 4 hours.

[0104] The operating parameters of the gas chromatograph used to measure the composition (including n-butane content) of the materials in the following examples and comparative examples were as follows: Agilent 7890A; column: HP-5, 60 m × 0.25 mm × 0.25 μm; chromatographic analysis method: injection volume 0.3 μL; injection port temperature 250℃; split ratio 45:1; column flow rate 1.0 mL / min; initial column temperature 50℃, held for 5 min, then increased to 150℃ at 15℃ / min, held for 4 min; FID detector, detector temperature 300℃.

[0105] The mixture of raw materials to be separated in the following examples and comparative examples consisted of 37.0 wt.% n-butane and 63.0 wt.% isobutane.

[0106] Example 1 Adopting such Figure 3 The gas-phase simulated moving bed adsorption separation device shown separates a mixture of raw materials. The gas-phase simulated moving bed consists of 6 adsorption columns, each with a volume V' of approximately 5.3 m³. 3Each adsorption column is filled with 3.9 tons of 5A molecular sieve as adsorbent. The operating temperature of the adsorption column is 180℃. The six adsorption columns are designated as Column 1, Column 2, Column 3, Column 4, Column 5, and Column 6, respectively. They are connected by connecting pipelines, each equipped with a valve, designated C-1 to C-6. Six valves on the pipeline connecting to the adjacent adsorbent beds for introducing raw materials are designated F-1 to F-6. Six valves on the pipeline connecting to the adjacent adsorbent beds for discharging desorbed material are designated E-1 to E-6. Six valves on the pipeline connecting to the adjacent adsorbent beds for discharging vacuum desorbed material are designated V-1 to V-6. (After connecting to the pipeline for discharging vacuum desorbed material, the pressure inside the adsorption column can be reduced to 50 kPa (absolute pressure), and the vacuum pump outlet pressure is not lower than 0.12 kPa.) The six valves on the pipeline connected to the connecting pipeline between two adjacent adsorbent beds for introducing the extracted reflux material into the upstream of the purification zone are designated as B-1 to B-6. The six valves on the pipeline connected to the connecting pipeline between two adjacent adsorbent beds for drawing out the residual material and pressurizing the adsorption column are designated as R-1 to R-6. There are a total of 36 on / off valves. A flow control device and a pressurization device are installed on the pipeline for introducing the extracted reflux material into the upstream of the purification zone, and a vacuum pump is installed on the pipeline for drawing out the desorbed material.

[0107] In a step time, such as Figure 3 As shown, column 1 is located in the vacuum desorption zone, column 2 in the depressurization desorption zone, column 3 in the purification zone, columns 4 and 5 in the adsorption zone, and column 6 in the gas-pressurization zone. Valves C-3 and C-4 connecting adjacent adsorption columns are open, while valves C-1, C-2, C-5, and C-6 are closed. Valves V-1 (for discharging vacuum desorbed material), E-2 (for discharging depressurization desorbed material), B-3 (for introducing refluxed material into the upstream of the purification zone), F-4 (for introducing raw material), R-5 (for discharging residual material), and R-6 (for pressurizing the adsorption column) are open. All other valves are closed.

[0108] In the next step, column 2 is in the vacuum desorption zone, column 3 is in the depressurization desorption zone, column 4 is in the purification zone, columns 5 and 6 are in the adsorption zone, and column 1 is in the gas-pressurization zone. Valves C-4 and C-5 connecting adjacent adsorption columns are open, while valves C-1, C-2, C-3, and C-6 are closed. Valves V-2 (for discharging evacuated material), E-3 (for discharging depressurized material), B-4 (for introducing reflux material into the upstream of the purification zone), F-5 (for introducing raw material), R-6 (for discharging residual material), and R-1 (for pressurizing the adsorption column) are open; all other valves are closed. This process continues for six steps until the gas-phase simulated moving bed returns to its initial state, completing one cycle. The step time t is 150 seconds, so one cycle of the simulated moving bed state switching is about 15 minutes.

[0109] The flow rate of extracted material E equals the flow rate of depressurized desorbed material plus the flow rate of vacuum desorbed material V minus the flow rate of extracted reflux material B. The flow rate of raw material F equals the flow rate of extracted material E plus the flow rate of raffinate material R. Vacuum desorbed material V and extracted reflux material B are intermediate materials in the process. The flow rates are average values, obtained by dividing the cumulative flow rate over one step time by one step time. The flow rate Q of the extracted reflux material (under operating conditions) is approximately 214 m³. 3 The extraction reflux coefficient ε is calculated to be 1.68 according to the formula ε=Q / (V' / t×3600).

[0110] The flow rate, pressure, and n-butane content of each major material are shown in Table 1, where the n-butane content was determined by gas chromatography.

[0111] Table 1 Material Name Mass flow rate (t / h) Pipeline pressure (MPa) n-Butane (wt.%) Raw material F 12.5 1.20 37.0 Residual material R 8.2 1.15 4.2 Extracted material E 4.3 0.12 99.5 Vacuum desorption material V 2.1 0.05 99.9 Extract reflux material B 4.2 1.25 99.5 Note: The pressure of material E extracted in the table corresponds to the pressure in the pipeline after the reflux is diverted.

[0112] Example 2 Adopting such Figure 1 The gas-phase simulated moving bed adsorption separation device shown separates a mixture of raw materials. The difference between this device and Example 1 is the absence of pipelines for extracting desorbed material and a vacuum pump. The gas-phase simulated moving bed comprises six adsorption columns, each with a volume V' of approximately 5.3 m³. 3Each adsorption column is filled with 3.9 tons of 5A molecular sieve as adsorbent. The operating temperature of the adsorption column is 180℃. The six adsorption columns are designated as Column 1, Column 2, Column 3, Column 4, Column 5, and Column 6, respectively. They are connected by connecting pipelines, each equipped with a valve, and these six valves are designated as C-1 to C-6. Six valves on the pipeline connecting the two adjacent adsorbent beds for introducing raw materials are designated as F-1 to F-6. Six valves on the pipeline connecting the two adjacent adsorbent beds for drawing out extracted material are designated as E-1 to E-6. Six valves on the pipeline connecting the two adjacent adsorbent beds for introducing extracted reflux material upstream of the purification zone are designated as B-1 to B-6. Six valves on the pipeline connecting the two adjacent adsorbent beds for drawing out residual material or for pressurizing the adsorption columns are designated as R-1 to R-6. A total of 30 on / off valves are used. Flow control and pressurization devices are installed on the pipeline for introducing extracted reflux material upstream of the purification zone.

[0113] Within one step time, column 1 is located in the desorption zone, columns 2 and 3 are located in the purification zone, columns 4 and 5 are located in the adsorption zone, and column 6 is located in the gas-pressurization zone. Valves C-2, C-3, and C-4 on the connecting pipeline between two adjacent adsorption columns are in the open state, while valves C-1, C-5, and C-6 are in the closed state. Valves E-1 on the pipeline for drawing out the extracted material, valve B-2 on the pipeline for introducing the extracted reflux material upstream of the purification zone, valve F-4 on the pipeline for introducing the raw material, valve R-5 on the pipeline for drawing out the residual material, and valve R-6 on the pipeline for pressurizing the adsorption column are in the open state, while all other valves are in the closed state.

[0114] In the next step time, column 2 is in the desorption zone, columns 3 and 4 are in the purification zone, columns 5 and 6 are in the adsorption zone, and column 1 is in the pressurization zone. Valves C-3, C-4, and C-5 on the connecting pipeline between adjacent adsorption columns are open, while valves C-1, C-2, and C-6 are closed. Valves E-2 on the pipeline for drawing out the extracted material, B-3 on the pipeline for introducing the extracted reflux material upstream of the purification zone, F-5 on the pipeline for introducing the raw material, R-6 on the pipeline for drawing out the residual material, and R-1 on the pipeline for pressurizing the adsorption column are open; all other valves are closed. This process continues for six steps, after which the simulated moving bed returns to its initial state, completing one cycle. The step time t is 150 seconds, therefore, one cycle of the simulated moving bed's state switching is approximately 15 minutes.

[0115] The flow rate of raw material F equals the flow rate of extracted material E plus the flow rate of retained material R. Extracted return material B is an intermediate material in the process. The flow rate is an average value, obtained by dividing the cumulative flow rate over one step time by one step time. The flow rate Q of the extracted return material (under operating conditions) is approximately 133 m³ / s. 3 The extraction reflux coefficient ε is calculated to be 1.05 according to the formula ε=Q / (V' / t×3600).

[0116] The flow rate, pressure, and n-butane content of each major material are shown in Table 2, where the n-butane content was determined by gas chromatography.

[0117] Table 2 Material Name Mass flow rate (t / h) Pressure (MPa) n-Butane (wt.%) Raw material F 8.0 1.20 37.0 Residual material R 5.2 1.15 3.4 Extracted material E 2.8 0.12 99.5 Extract reflux material B 2.7 1.30 99.5 .

[0118] Comparative Example 1 A liquid-phase simulated moving bed adsorption separation method was used to separate the mixture of raw materials. The feed flow rate was 12.5 t / h, as shown in Table 3 below. The liquid-phase simulated moving bed was an adsorption tower with 12 beds, each bed packed with 5.5 tons of 5A molecular sieve as adsorbent. n-Octane was used as the desorbent. The operating temperature of the adsorption tower was 100℃, and the operating pressure was 2.4 MPa. The adsorption tower was divided into sections as follows: Figure 2 As shown, there are 3 beds between the desorbent D entering and the extract E exiting, forming the desorption zone; 4 beds between the extract E exiting and the adsorbent material F entering, forming the purification zone; 3 beds between the adsorbent material F entering and the raffinate R exiting, forming the adsorption zone; and 2 beds between the raffinate R exiting and the desorbent D entering, forming the buffer zone. Two flushing streams are set up, labeled C1 (flushing liquid 1) and C3 (flushing liquid 2), where C1 uses the desorbent, flushed into the tower, with the feed position one bed upstream of the extract exit position; C3 uses the extract, flushed into the tower, with the feed position one bed upstream of the feed material entry position. Each feed stream is connected to each bed via a pipeline equipped with a switching valve. With 12 beds and 6 feed streams, there are a total of 72 switching valves. The step time is 170 seconds, and one cycle of state switching in the liquid-phase simulated moving bed is approximately 34 minutes.

[0119] The flow rates and n-butane content of each major material are shown in Table 3, where the n-butane content was determined by gas chromatography.

[0120] Table 3 Material Name Flow rate (t / h) n-Butane (wt.%) Raw material F 12.5 37.0 Desorbent D 28.6 0.0 Extracted fluid E 17.9 23.3 Residual liquid R 23.2 2.0 .

[0121] The extract E and raffinate R are respectively fed into the extract column and raffinate column for distillation, separating the n-octane from the n-butane and isobutane, and then recycled back to the adsorption column as a desorbent. Measurements show that the distilled extract yields n-butane with a purity of 99.5%.

[0122] A comparison of Examples 1-2 and Comparative Example 1 shows that the purity of n-butane in the extracted material obtained using the method and apparatus of the present invention is comparable to that obtained using the method and apparatus of a liquid-phase simulated moving bed. However, the method and apparatus of the present invention do not introduce a desorbent, and therefore do not require an additional distillation process, thus eliminating the need for the steps of adding a desorbent and distilling the raffinate, as well as the associated energy consumption and costs.

[0123] Comparative Example 2 The structure and layout of the gas-phase simulated moving bed adsorption separation device are the same as in Example 1. The mixture of raw materials to be separated is adsorbed and separated according to the method of Example 1, except that the flow rate of the extracted reflux material is lower.

[0124] Table 4 shows the flow rate, pressure, and n-butane content of each major material. The n-butane content was determined by gas chromatography. The flow rate is an average value, obtained by dividing the cumulative flow rate over one step time by one step time.

[0125] The flow rate Q of the extracted reflux material (under operating conditions) is approximately 75 m³. 3 The extraction reflux coefficient ε is calculated to be 0.59 according to the formula ε=Q / (V' / t×3600).

[0126] Table 4 Material Name Mass flow rate (t / h) Pressure (MPa) n-Butane (wt.%) Raw material F 12.5 1.20 37.0 Residual material R 7.9 1.15 1.8 Extracted material E 4.6 0.12 97.5 Vacuum desorption material V 2.1 0.05 99.5 Extract reflux material B 1.5 1.25 97.5 .

[0127] Comparative Example 3 The structure and layout of the gas-phase simulated moving bed adsorption separation device are the same as in Example 1. The mixture of raw materials to be separated is adsorbed and separated according to the method of Example 1, except that the flow rate of the extracted reflux material is higher.

[0128] Table 5 shows the flow rate, pressure, and n-butane content of each major material. The n-butane content was determined by gas chromatography. The flow rate is an average value, obtained by dividing the cumulative flow rate over one step time by one step time.

[0129] The flow rate Q of the extracted reflux material (under operating conditions) is approximately 240 m³. 3 The extraction reflux coefficient ε is calculated to be 1.89 according to the formula ε=Q / (V' / t×3600).

[0130] Table 5 Material Name Mass flow rate (t / h) Pressure (MPa) n-Butane (wt.%) Raw material F 12.5 1.20 37.0 Residual material R 9.0 1.15 12.8 Extracted material E 3.5 0.12 99.5 Vacuum desorption material V 2.1 0.05 99.9 Extract reflux material B 4.7 1.25 99.5 .

[0131] A comparison of Example 1 and Comparative Example 2 shows that the extraction reflux coefficient ε within the range of the present invention is beneficial for improving the purity of n-butane in the extracted material. Specifically, the purity of n-butane in the extracted material of Example 1 reaches 99.5% for superior industrial grade, while the purity of n-butane in the extracted material of Comparative Example 2 is even lower than 98% for basic industrial grade. A comparison of Example 1 and Comparative Example 3 shows that the extraction reflux coefficient ε within the range of the present invention is beneficial for achieving a higher n-butane recovery rate. Specifically, the n-butane recovery rate of Example 1 is 93.0%, while the n-butane recovery rate of Comparative Example 3 is only 75.7%.

[0132] The embodiments described above merely illustrate several implementations of the present invention and should not be construed as limiting the scope of the present 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 protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for separating a mixture using a gas-phase simulated moving bed adsorption, the gas-phase simulated moving bed comprising multiple adsorbent beds packed with adsorbent, sequentially divided into desorption zones, purification zones, and adsorption zones, wherein the method comprises the following steps: 1) The mixture to be separated is injected from the upstream of the adsorption zone, and the adsorbent in the adsorption zone selectively adsorbs the components with stronger adsorption capacity in the mixture under pressure P1; 2) The components adsorbed on the adsorbent are desorbed in the desorption zone under pressure P2, where P1 is greater than P2; and 3) A portion of the extracted material flowing out downstream of the desorption zone is returned to the upstream of the purification zone; Preferably, the extraction reflux coefficient ε=Q / (V' / t×3600) is 0.8-1.8, more preferably 1.0-1.7, where Q is the volumetric flow rate of the extracted reflux material, in m³ / s. 3 / h, V' is the volume of a single adsorbent bed, in m³. 3 t is the step time, in seconds.

2. The method according to claim 1, wherein, The gas-phase simulated moving bed further includes at least one adsorbent bed divided into an aeration and pressurization zone, which is preferably connected to a pipeline for extracting residual material. The adsorbent bed of the gas-phase simulated moving bed is connected in series by pipelines to form a ring arrangement, and is sequentially divided into the desorption zone, purification zone, adsorption zone and gas-pressurization zone.

3. The method according to claim 2, wherein, During the operation of the gas-phase simulated moving bed, the adjacent adsorbent beds in the purification zone and adsorption zone are interconnected, while the adsorbent beds in the purification zone and adsorption zone are not interconnected with the adsorbent beds in the desorption zone or the gas-pressurization zone, and the adsorbent beds in the desorption zone and the gas-pressurization zone are also not interconnected.

4. The method according to claim 1 or 2, wherein, The extracted material includes vacuum desorbed material and depressurized desorbed material; Preferably, the flow rate of the extracted material is equal to the flow rate of the evacuated desorbed material plus the flow rate of the depressurized desorbed material minus the flow rate of the extracted return material; Preferably, after the evacuated desorbed material and the depressurized desorbed material merge to form the extracted material, a portion of the extracted material is returned to the upstream of the purification zone as extracted reflux material, and the unreturned extracted material flows out of the gas phase simulated moving bed. Preferably, the pressure of the pipeline used to draw out the evacuated desorbed material is lower than the pressure of the pipeline used to draw out the depressurized desorbed material, and the pressure of the pipeline used to draw out the evacuated desorbed material is not higher than 0.06 MPa, preferably 0.01 MPa to 0.06 MPa.

5. The method according to claim 4, wherein, Pipelines for drawing out desorbed material, pipelines for drawing out depressurized desorbed material, pipelines for drawing out residual material and pressurizing the adsorption column (when the gas-phase simulated moving bed includes a pressurization zone), pipelines for introducing extracted reflux material into the upstream of the purification zone, and pipelines for introducing raw materials are connected to the connecting pipelines between each pair of adjacent adsorbent beds and are equipped with valves respectively. During the operation of the gas-phase simulated moving bed, the valves on the pipeline downstream of the evacuation-desorption zone for leading out the evacuated desorbed material, the valves on the pipeline downstream of the depressurization-desorption zone for leading out the depressurization-desorption material, the valves on the pipeline downstream of the raffinate zone for leading out the raffinate material, the valves on the pipeline upstream of the purification zone for introducing the extracted reflux material upstream of the purification zone, the valves on the pipeline upstream of the adsorption zone for introducing the raw material, and the valves on the pipeline for pressurizing the adsorption column (when the gas-phase simulated moving bed includes a pressurization zone) are in the open state, while other valves are in the closed state.

6. The method according to claim 1 or 2, wherein, The method does not introduce a desorbent; The pressure of the pipeline used to extract the material is lower than the pressure of the pipeline used to introduce the raw material. The pressure of the pipeline used to remove residual material is lower than the pressure of the pipeline used to introduce raw material; and / or The pressure of the pipeline used to introduce the extracted reflux material upstream of the purification zone is higher than the pressure of the pipeline used to introduce the raw material.

7. The method according to claim 1 or 2, wherein, The mixture comprises at least two C2-C4 alkanes and / or alkenes, preferably n-butane and isobutane; Preferably, the adsorption separation of the mixture is carried out at a temperature of 20°C to 220°C, more preferably 80°C to 200°C, and even more preferably 120°C to 200°C. Preferably, the pressure of the pipeline used to introduce the raw material is 0.2 MPa to 3 MPa, more preferably 0.5 MPa to 2.5 MPa, and even more preferably 0.8 MPa to 2.0 MPa; Preferably, the pressure of the pipeline used to extract residual material is 0.02 MPa to 0.2 MPa lower than the pressure of the pipeline used to introduce raw material, more preferably 0.03 MPa to 0.1 MPa. Preferably, the pressure of the pipeline used to draw out the extracted material is 0.08 MPa to 0.5 MPa, more preferably 0.1 MPa to 0.3 MPa. When the desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, the pressure of the pipeline used to draw out the extracted material refers to the pressure of the pipeline used to draw out the extracted material at the position after the vacuum desorbed material and the pressure reduction desorbed material have merged to form the extracted material. Preferably, the desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, and the pressure of the pipeline for leading out the vacuum desorbed material is 0.01 MPa to 0.06 MPa; Preferably, the pressure of the pipeline used to introduce the extracted reflux material upstream of the purification zone is 0.02 MPa to 0.2 MPa higher than the pressure of the pipeline used to introduce the raw material, more preferably 0.02 MPa to 0.1 MPa; and / or Preferably, the step time is 20 s to 500 s, more preferably 50 s to 200 s.

8. A gas-phase simulated moving bed adsorption separation device, wherein the simulated moving bed comprises multiple adsorbent beds arranged in a ring by being connected in series end to end by pipelines, the adsorbent beds being sequentially divided into a desorption zone, a purification zone, an adsorption zone, and a preferred gas-pressurization zone; a valve is provided on the connecting pipeline between two adjacent adsorbent beds; Each of the aforementioned connecting lines is respectively connected to a line for introducing raw materials, a line for drawing out extracted materials, a line for drawing out residual materials and pressurizing the gas-pressurizing zone, and a line for introducing extracted reflux materials upstream of the purification zone; and the line for introducing extracted reflux materials upstream of the purification zone is connected to the line for drawing out extracted materials. The pipeline used to introduce the extracted reflux material into the upstream of the purification zone is preferably equipped with a pressurization device and / or a flow control device, and the adsorbent bed in the aeration pressurization zone is preferably connected to the pipeline used to extract the residual material.

9. The apparatus according to claim 8, wherein, The desorption zone includes a vacuum desorption zone and a pressure reduction desorption zone, and the pipeline for extracting the material includes a pipeline connected in parallel for leading out the vacuum desorbed material and a pipeline for leading out the pressure reduction desorbed material. One end of each of these two pipelines is connected to the connecting pipeline between the adsorbent beds, and the other end is connected to allow the vacuum desorbed material and the pressure reduction desorbed material to come together to form the extracted material. Preferably, the pipeline used to draw out the desorbed material is equipped with a vacuum pump.

10. The apparatus according to claim 8 or 9, wherein, The connecting pipeline between two adjacent adsorbent beds is divided into two sides by a valve. The pipeline for introducing raw materials and the pipeline for introducing the extracted reflux material upstream of the purification zone are connected to the connecting pipeline on one side of the valve. The pipeline for leading out the extracted material and the pipeline for leading out the residual material and pressurizing the gas-pressurizing zone are connected to the connecting pipeline on the other side of the valve. When the desorption zone includes a vacuum desorption zone and a depressurization desorption zone, the pipelines for leading out the extracted material include pipelines for leading out the vacuum desorbed material and pipelines for leading out the depressurization desorbed material.

11. The method according to claim 8 or 9, wherein, The gas-phase simulated moving bed has at least five adsorbent beds, of which at least two adsorbent beds are used for the adsorption zone. Preferably, the adsorbent bed is contained in an adsorption column, and each adsorption column has a volume of 0.1 m³. 3 Up to 200 m 3 , or 0.1 m 3 Up to 100 m 3 , or 1 m 3 up to 50 m 3 , or 1 m 3 Up to 20 m 3 ; Preferably, the number of adsorbent beds in the adsorption zone accounts for no less than one-third of the total number of adsorbent beds in the gas-phase simulated moving bed. More preferably, the gas-phase simulated moving bed includes six adsorbent beds arranged in a ring by being connected end-to-end through pipelines, wherein one adsorbent bed is used for a vacuum desorption zone, one adsorbent bed is used for a depressurization desorption zone, one adsorbent bed is used for a purification zone, two adsorbent beds are used for an adsorption zone, and one adsorbent bed is used for a gas-pressurization zone; or wherein one adsorbent bed is used for a desorption zone, two adsorbent beds are used for a purification zone, two adsorbent beds are used for an adsorption zone, and one adsorbent bed is used for a gas-pressurization zone.

12. The method according to claim 8 or 9, wherein, The adsorbent is a molecular sieve, silica gel, alumina, activated carbon, or a combination thereof; The adsorbent is spherical, cylindrical, strip-shaped, and / or irregularly shaped; and / or The adsorbent has a particle size of 0.1 mm to 5 mm, for example, 0.1 mm to 1 mm.

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