Gas purification method and gas purification unit

Abstract

To provide a gas purification method and a gas purification unit which enable an effective utilization of a regeneration gas without needing a compressor or the like and an increase in the recovery rate of a product gas by cutting down the exhaust gas amount of the regeneration gas.SOLUTION: This invention includes a method where an adsorption process for adsorbing impurities of a raw material gas G1 away by using three adsorption towers 2A, 2B, 2C, and a regeneration process for desorbing the impurities out of the adsorption towers 2A, 2B, 2C by heating the adsorption towers 2A, 2B, 2C are executed by repeating, and where at least one of the adsorption towers 2A, 2B, 2C executes the adsorption process to use a part of a refined gas G2 obtained by removing the impurities out of the raw material gas G1, exhausted out of the adsorption towers in the adsorption process, as a regeneration gas G3 which purges the adsorption towers 2A, 2B, 2C. When at least two adsorption towers 2B, 2C of the three adsorption towers 2A, 2B, 2C execute the regeneration process, the regeneration gas G3 is circulated in order through the respective adsorption towers 2B, 2C which execute the regeneration process.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas purification method and a gas purification apparatus. [Background technology]

[0002] Conventionally, in an industrial gas production process, a gas purification apparatus (TSA apparatus) employing, for example, thermal swing adsorption (TSA) has been known as a means for purifying a gas containing a substance to be removed to obtain a product gas (purified gas). In general, a gas purification apparatus to which the TSA method is applied is widely configured to have two adsorption towers for adsorbing impurities in order to continuously supply the product gas, and to alternate between a purification process (impurity adsorption) and a regeneration process (impurity desorption), in which the two adsorption towers are operated in a two-tower switching configuration.

[0003] In a typical gas purification apparatus using the TSA method and having a two-tower switching configuration, when regenerating the adsorbent in the adsorption tower after gas purification, either a part of the product gas or a gas that is non-adsorbable to the adsorbent is supplied as a regeneration gas into the adsorption tower, and the adsorbent in the adsorption tower is heated while desorbing the substances to be removed. In this case, the adsorbent is heated, for example, by heat input from a regeneration gas heated by a gas heating heater or a jacket heater installed in the adsorption tower. Here, activated carbon and zeolite, which are commonly used as adsorbents, have low thermal conductivity, so it is difficult to heat them uniformly only by external heating such as a jacket heater, and therefore heat transfer using the regeneration gas as a medium is very important, and this tendency becomes more pronounced as the adsorption tower becomes larger. In addition, the regeneration gas flow rate required for regeneration of the adsorbent, that is, the amount of heat that the gas needs to transfer per unit time, is determined by the specific heat and temperature of the regeneration gas during the regeneration process, the regeneration time, the amount of the adsorbed substances to be removed, the amount of heat required for desorption, the heat capacity of the adsorption tower and the adsorbent, etc.

[0004] As mentioned above, when a part of the product gas is used as the regeneration gas, the regeneration gas directly leads to the loss of the product gas. In addition, even if a gas that is non-adsorbable to the adsorbent is prepared separately and used as the regeneration gas, it will not only increase utility costs, but also cause problems such as the non-adsorbable gas remaining in the adsorption tower becoming an impurity component of the product gas and reducing the purity of the product gas. For this reason, improving the recovery rate of the product gas by reducing the exhaust gas derived from the regeneration gas and efficiently heating and cooling the adsorbent are important factors for improving the economic efficiency of gas purification equipment that applies the TSA method.

[0005] On the other hand, in the case of the above-mentioned two-tower switching gas purification apparatus (TSA apparatus), the time that can be allocated to the regeneration process depends on the amount of adsorbent packed in the adsorption tower, that is, the time of the adsorption process. For this reason, for example, when the flow rate of the regeneration gas is reduced, the amount of heat that the regeneration gas can transfer per unit time decreases, and the amount of heat that can be removed per unit time during cooling also decreases. Even if the regeneration gas temperature during regeneration is increased, the amount of heat to be removed during cooling increases, so there is a possibility that the adsorbent will not be cooled sufficiently. For this reason, in a gas purification apparatus (TSA apparatus) having a two-tower switching configuration, there is a limit to the improvement of the recovery rate by reducing the flow rate of the regeneration gas.

[0006] Here, for example, the technique described in Patent Document 1 is known as a means for improving the recovery rate of the product gas in a gas purification device. The regenerative desulfurization apparatus described in Patent Document 1 is an apparatus in which two regenerative gas purification apparatuses (hereinafter, for convenience of explanation, referred to as apparatus A and apparatus B, respectively) are connected in series, and the exhaust gas of the regenerated gas that has been passed through the adsorption tower on the regeneration side of apparatus A is passed as the regenerated gas through the adsorption tower on the regeneration side of apparatus B. According to the technology described in Patent Document 1, the amount of regenerated gas used in the entire apparatus can be reduced.

[0007] Furthermore, as another means for improving the recovery rate of the product gas in a gas purification apparatus, for example, the technique described in Patent Document 2 is known. According to the helium purification device described in Patent Document 2, the exhaust gas of the regeneration gas is merged with the raw gas line and recycled as raw gas, thereby improving the recovery rate of the product gas by reusing the exhaust gas of the regeneration gas. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5074116 [Patent Document 2] Patent No. 4058278 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the technology described in the above-mentioned Patent Document 1 cannot reduce the amount of exhaust gas from the regeneration gas in a single unit (for example, unit A or unit B) and cannot improve the recovery rate of the product gas.

[0010] Furthermore, in the technology described in Patent Document 2, in order to reuse the exhaust gas of the regeneration gas, a means for increasing the pressure of the exhaust gas to a level equal to or higher than that of the raw material gas, such as a compressor for pressurizing the exhaust gas, is required. For this reason, there is a concern that the applicable processes will be limited due to factors such as an increase in the cost of the equipment.

[0011] The present invention has been made in consideration of the above problems, and has an object to provide a gas purification method and gas purification apparatus that can efficiently utilize regeneration gas without requiring a compressor or the like, reduce the amount of exhaust gas from the regeneration gas, and increase the recovery rate of the product gas. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above problems. As a result, they have found that by applying a TSA device having a multi-tower switching configuration with three or more adsorption towers and providing piping to connect the respective adsorption towers, it is possible to efficiently utilize the regeneration gas without requiring a compressor or the like. That is, they have found that by adopting a method in which the regeneration gas is sequentially circulated through each of the adsorption towers performing the regeneration process when at least two of the three adsorption towers perform the regeneration process, it is possible to reduce the amount of exhaust gas from the regeneration gas and increase the recovery rate of the product gas, and have completed the present invention. That is, the present invention has the following aspects.

[0013] [1] A gas purification method using at least three adsorption towers filled with an adsorbent that adsorbs impurities in a raw gas, repeatedly carrying out an adsorption step of adsorbing and removing the impurities in the raw gas in the adsorption towers by a Thermal Swing Adsorption (TSA) method, and a regeneration step of heating the adsorption towers to remove the impurities adsorbed in the adsorption towers from the adsorption towers, wherein at least one of the three adsorption towers performs the adsorption step, and a portion of the purified gas obtained by removing the impurities from the raw gas and discharged from the adsorption towers in the adsorption step is used as a regeneration gas for purging the adsorption towers in the regeneration step, wherein the gas purification method is characterized in that when at least two of the three adsorption towers perform the regeneration step, the regeneration gas is sequentially circulated to each of the adsorption towers performing the regeneration step. [2] The gas purification method according to the above item [1], characterized in that the regeneration step includes at least a heating step of heating the adsorption tower and a cooling step of cooling the adsorption tower after the heating step to a temperature at which the adsorption step can be performed, and when at least one of the three adsorption towers performs the heating step and at least one of the adsorption towers performs the cooling step, the regeneration gas is introduced into the adsorption tower performing the cooling step, and the regeneration gas discharged from the adsorption tower performing the cooling step is introduced into the adsorption tower performing the heating step. [3] The gas purification method according to [1] or [2] above, characterized in that the temperature of the regeneration gas discharged from the adsorption tower undergoing the cooling step is cooled to 150°C or less before being introduced into the adsorption tower undergoing the heating step. [4] The gas purification method according to [1] or [2] above, wherein the component contained in the impurities to be adsorbed and removed by the adsorbent is at least one of H2O, CO2, O2, CO, and hydrocarbons. [5] A gas purification apparatus for producing a purified gas by adsorbing and removing impurities from a raw material gas, comprising at least three adsorption towers filled with an adsorbent for adsorbing and removing the impurities from the raw material gas, a raw material gas inlet pipe connected to one end of each of the adsorption towers for introducing the raw material gas into the adsorption tower, and a regenerated gas outlet pipe connected to the other end of each of the adsorption towers for discharging the purified gas from the adsorption tower, and a regenerated gas inlet pipe connected to the other end of each of the adsorption towers for introducing the regenerated gas into the adsorption tower, a heating unit for heating the adsorbent or the regenerated gas, which is provided in the adsorption tower; and a gas purifying apparatus comprising: an adsorption tower connecting pipe between the one end of the adsorption tower to which the regenerated gas discharge pipe is connected and the other end of the adsorption tower to which the regenerated gas introduction pipe is connected, and a switching valve is provided in the adsorption tower connecting pipe between the one end of the adsorption tower to which the regenerated gas introduction pipe is connected, and the adsorption tower connecting pipe is provided between each of the three adsorption towers. [6] The gas purification apparatus according to [5], wherein the adsorption tower connecting pipe is provided so that all three of the adsorption towers are connected in a circular shape. [7] The gas purification apparatus according to [5] or [6] above, wherein the heat-resistant temperature of the switching valve provided in the adsorption tower connecting piping is at least equal to or higher than the heating temperature of the adsorption tower. [8] The gas purification apparatus according to the above [5] or [6], characterized in that a heat exchanger for cooling the regenerated gas flowing through the adsorption tower connecting pipe is provided on the primary side of the switching valve provided in the adsorption tower connecting pipe. [9] The gas purification apparatus according to the above [5] or [6], characterized in that a heat exchanger for cooling the gas circulating through the regeneration gas exhaust piping is provided between the adsorption tower and an on-off valve provided in the regeneration gas exhaust piping.

[10] The gas purification apparatus according to [9] above, characterized in that a drain trap is provided inside the heat exchanger provided in the regeneration gas exhaust piping or in the regeneration gas exhaust piping on the outlet side of the heat exchanger.

[11] The gas purification apparatus according to [5] or [6] above, characterized in that the components contained in the impurities adsorbed and removed by the adsorbent are at least one of H2O, CO2, O2, CO, and hydrocarbons. Effect of the Invention

[0014] As described above, the gas purification method according to the present invention employs a method in which, when at least two of the three adsorption towers are performing the regeneration process, the regeneration gas is sequentially circulated through each of the adsorption towers performing the regeneration process. According to the present invention, by adopting the above-mentioned method, the flow rate of the regeneration gas required for heating and cooling the adsorption tower can be reduced, and the flow rate of the exhaust gas of the regeneration gas discharged from the adsorption tower in the regeneration process can also be reduced. This reduces the amount of exhaust gas of the regeneration gas contained in the refined gas, and makes it possible to increase the recovery rate as the product gas.

[0015] Furthermore, in the gas purification apparatus according to the present invention, an adsorption tower connecting pipe is provided between each of the three adsorption towers, connecting one end of the adsorption tower to which the regenerated gas exhaust pipe is connected and the other end to which the regenerated gas introduction pipe is connected, and a switching valve is provided in the adsorption tower connecting pipe. According to the present invention, by adopting the above configuration, the flow rate of the regeneration gas required for heating and cooling the adsorption tower can be reduced, and the flow rate of the exhaust gas of the regeneration gas discharged from the adsorption tower can also be reduced. In addition, the regeneration gas can be efficiently used without requiring a compressor or the like. This makes it possible to realize a gas purification device that reduces the amount of exhaust gas of the regeneration gas contained in the purified gas and increases the recovery rate as a product gas. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram for explaining a gas purification method and a gas purification apparatus according to a first embodiment of the present invention, and is a system diagram showing the overall configuration of the gas purification apparatus. [Diagram 2] FIG. 2 is a schematic diagram for explaining the gas purification method and the gas purification apparatus according to the first embodiment of the present invention, and is a system diagram showing an example of the flows of the raw material gas, the purified gas, and the regeneration gas based on a valve time chart in the gas purification apparatus shown in FIG. [Diagram 3] FIG. 2 is a schematic diagram for explaining the gas purification method and gas purification apparatus according to the first embodiment of the present invention, and is a system diagram showing another example of the flows of the raw material gas, purified gas, and regeneration gas in the gas purification apparatus shown in FIG. [Figure 4] FIG. 4 is a schematic diagram for explaining the gas purification method and the gas purification apparatus according to the first embodiment of the present invention, and is a valve time chart showing the opening and closing operations of each valve for controlling the flows of the raw material gas, the purified gas, and the regeneration gas shown in FIG. 2 and FIG. [Diagram 5] FIG. 4 is a schematic diagram for explaining a gas purification method and a gas purification apparatus according to a second embodiment of the present invention, and is a system diagram showing the overall configuration of the gas purification apparatus. [Figure 6] FIG. 11 is a schematic diagram for explaining a gas purification method and a gas purification apparatus according to a third embodiment of the present invention, and is a system diagram showing the overall configuration of the gas purification apparatus. [Figure 7]FIG. 7 is a diagram for illustrating the gas purification method and the gas purification apparatus according to the second to fourth embodiments of the present invention, and is a valve time chart showing the opening and closing operations of each valve for controlling the flow of the raw material gas, the purified gas, and the regeneration gas shown in FIG. 5 and FIG. [Figure 8] FIG. 11 is a schematic diagram for explaining a gas purification method and a gas purification apparatus according to a fourth embodiment of the present invention, and is a system diagram showing the overall configuration of the gas purification apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, first to fourth embodiments of a gas purification method and a gas purification apparatus according to the present invention will be described with reference to Figs. 1 to 8 as appropriate. In addition, the drawings used in the following description may show characteristic parts in an enlarged or simplified form for the sake of convenience in order to make the characteristics easier to understand. Furthermore, the materials and the like exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be appropriately modified and implemented within the scope of the present invention.

[0018] <First embodiment> A gas purification method and a gas purification apparatus according to a first embodiment of the present invention will be described below.

[0019] [Gas purification equipment] First, a gas purification apparatus that can be used in the operation according to the gas purification method of this embodiment will be described in detail below. FIG. 1 is a system diagram showing an overall schematic configuration of a gas purification device 1 according to the first embodiment. 2 and 3 are system diagrams showing the flows of the raw material gas, the refined gas, and the regenerated gas based on valve time charts in the gas refinement apparatus 1 shown in FIG. FIG. 4 is a valve time chart showing the opening and closing operations of each valve for controlling the flows of the raw material gas, purified gas, and regenerated gas shown in FIGS. 2 and 3 during the operation of the gas purification apparatus 1 shown in FIG.

[0020] The gas purification apparatus 1 of this embodiment is a so-called TSA apparatus that removes impurities from a raw material gas G1 by the TSA method to obtain a purified gas G2. Specifically, as shown in Fig. 1, the gas purification apparatus 1 of this embodiment is roughly configured to include adsorption towers 2A, 2B, and 2C, a raw material gas introduction path (raw material gas introduction piping) L1, a product gas discharge path (product gas discharge piping) L2, a regenerated gas introduction path (regenerated gas introduction piping) L3, and a regenerated gas discharge path (regenerated gas discharge piping) L4.

[0021] More specifically, the gas purification apparatus 1 includes three adsorption towers 2A, 2B, and 2C filled with an adsorbent 6 for adsorbing and removing impurities from a raw material gas G1. Each of the adsorption towers 2A, 2B, and 2C is provided with a heating unit 9 for heating the adsorbent 6 or the regeneration gas G3. The gas purification apparatus 1 also includes a raw material gas inlet path L1, which is connected to one end 2a of each of the adsorption towers 2A, 2B, and 2C, for introducing a raw material gas G1 into the adsorption towers 2A, 2B, and 2C, and a regeneration gas outlet path L4, which discharges a regeneration gas G3 from the adsorption towers 2A, 2B, and 2C. The gas purification apparatus 1 also includes a product gas discharge path L2, which discharges the purified gas G2 from the adsorption towers 2A, 2B, and 2C, and a regeneration gas introduction path L3, which introduces the regeneration gas into the adsorption towers 2A, 2B, and 2C, and are connected to the other ends 2b of the adsorption towers 2A, 2B, and 2C, respectively. In addition, the gas purification apparatus 1 is equipped with opening and closing valves V1a, V1b, V1c, V2a, V2b, V2c, V3a, V3b, V3c, V4a, V4b, and V4c, which are provided on one end 2a or the other end 2b of the adsorption towers 2A, 2B, and 2C, respectively, in the raw gas inlet path L1, the product gas outlet path L2, the regenerated gas inlet path L3, and the regenerated gas outlet path L4.

[0022] In the gas purification apparatus 1 of this embodiment, an adsorption tower connecting path (adsorption tower connecting piping) L5 is provided between each of the three adsorption towers 2A, 2B, and 2C, connecting one end 2a of the adsorption towers 2A, 2B, and 2C to which the regeneration gas discharge path L4 is connected and the other end 2b to which the regeneration gas introduction path L3 is connected. In addition, the adsorption tower connecting path L5 is provided with switching valves V5a, V5b, V5c, V5d, V5e, and V5f in the path near the adsorption towers 2A, 2B, and 2C, respectively.

[0023] The gas purification apparatus 1 in the illustrated example is provided with connection pipes L6a, L6b, and L6c that connect the junction of the raw gas introduction path L1 and the regeneration gas discharge path L4 to one end 2a of each of the three adsorption towers 2A, 2B, and 2C, and connection pipes L7a, L7b, and L7c that connect the junction of the product gas discharge path L2 and the regeneration gas introduction path L3 to the other end 2b of each of the three adsorption towers 2A, 2B, and 2C. Furthermore, the gas purification apparatus 1 in the illustrated example is provided with a regeneration gas flow rate adjustment valve NV1 provided in the regeneration gas introduction path L3 near the branch point from the product gas discharge path L2.

[0024] The gas purification apparatus 1 of this embodiment is configured to have the adsorption tower connecting path L5 as described above, so that the three adsorption towers 2A, 2B, and 2C are connected to each other by circular paths.

[0025] The raw gas introduction path L1 is a path for introducing the raw gas G1 to be purified into the adsorption towers 2A, 2B, and 2C of the gas purification apparatus 1. One end of the raw gas introduction path L1 in the illustrated example is connected to a raw gas storage means (not shown), and the other end is branched into three, which are connected to connection pipes L6a, L6b, and L6c connected to one ends 2a of the three adsorption towers 2A, 2B, and 2C, respectively. The connection point between the raw gas introduction path L1 and the connection pipes L6a, L6b, and L6c is the junction of the raw gas introduction path L1, the regeneration gas discharge path L4, and the adsorption tower connecting path L5.

[0026] The branch paths at the other end of the source gas introduction path L1 are provided with on-off valves V1a, V1b, and V1c, respectively, so that the flow of the source gas G1 can be started and stopped.

[0027] The product gas discharge path L2 is a path for extracting the purified gas G2 purified in the adsorption towers 2A, 2B, and 2C as a product gas (purified gas G2). One end of the product gas discharge path L2 in the illustrated example is branched into three, and is connected to connection pipes L7a, L7b, and L7c connected to the other ends 2b of the three adsorption towers 2A, 2B, and 2C, respectively, and the other end is connected to a product gas storage means (not shown). In addition, the product gas discharge path L2 has a branch point to a regeneration gas introduction path L3 near the other end.

[0028] At one end of the product gas discharge path L2, just before it branches into three connecting pipes L7a, L7b, and L7c, opening and closing valves V2a, V2b, and V2c are provided, respectively, so that the flow of refined gas G2, which becomes the product gas, can be started and stopped.

[0029] The regeneration gas introduction path L3 is a path for extracting a part of the refined gas G2 from the product gas discharge path L2 as a regeneration gas G3. One end of the regeneration gas introduction path L3 is connected to the product gas discharge path L2 and branches off from the product gas discharge path L2 at a position closer to the other end than the branch points toward the connecting pipes L7a, L7b, and L7c.

[0030] The other end of the regeneration gas introduction path L3 in the illustrated example is branched into three, and is connected to connection pipes L7a, L7b, and L7c that are connected to the other ends 2b of the three adsorption towers 2A, 2B, and 2C, respectively. In addition, at the other end of the regeneration gas introduction path L3, just before it branches into three connecting pipes L7a, L7b, and L7c, opening and closing valves V3a, V3b, and V3c are provided, respectively, so that the flow of the regeneration gas G3 can be started and stopped.

[0031] As described above, the regeneration gas introduction path L3 is provided with the regeneration gas flow rate control valve NV1 in the path near the branch point from the product gas discharge path L2. This regeneration gas flow rate control valve NV1 controls the flow rate of the regeneration gas G3 in the regeneration process for regenerating the adsorbent 6 filled in the adsorption towers 2A, 2B, and 2C, and supplies a predetermined flow rate of the regeneration gas G3 to the adsorption towers 2A, 2B, and 2C. The regeneration gas flow rate adjusting valve NV1 is not particularly limited, and for example, a general flow meter or a flow rate control device such as an MFC (Mass Flow Controller) can be used.

[0032] The regeneration gas discharge path L4 is a path for discharging the regeneration gas G3 used in the regeneration step as exhaust gas from the adsorption towers 2A, 2B, and 2C. One end of the regeneration gas discharge path L4 branches into three and is connected to connection pipes L6a, L6b, and L6c that are connected to one ends 2a of the three adsorption towers 2A, 2B, and 2C, respectively, and the other end is connected to an exhaust gas treatment means (not shown).

[0033] In addition, on one end side of the regeneration gas discharge path L4, just before it branches into three connecting pipes L6a, L6b, and L6c, opening and closing valves V4a, V4b, and V4c are provided, respectively, so that it is possible to start and stop the flow of the regeneration gas G3 discharged as exhaust gas from the adsorption towers 2A, 2B, and 2C.

[0034] As described above, the adsorption tower connecting path L5 is provided between each of the three adsorption towers 2A, 2B, and 2C, connecting one end 2a of the adsorption towers 2A, 2B, and 2C to which the regeneration gas discharge path L4 is connected and the other end 2b to which the regeneration gas introduction path L3 is connected. In addition, the adsorption tower connecting path L5 is provided with switching valves V5a, V5b, V5c, V5d, V5e, and V5f in the path near the adsorption towers 2A, 2B, and 2C, respectively.

[0035] In the illustrated example, one end of the adsorption tower connecting path L5 branches into three and is connected to connecting pipes L6a, L6b, and L6c that are connected to one end 2a of each of the three adsorption towers 2A, 2B, and 2C, respectively. In addition, like one end side, the adsorption tower connecting path L5 also branches into three on the other end side, and is connected to connecting pipes L7a, L7b, and L7c that are connected to the other ends 2b of the three adsorption towers 2A, 2B, and 2C, respectively.

[0036] Either one of switch valves V5a, V5b, or V5c is disposed in the path near the connection portion between one end of the adsorption tower connecting path L5 and the connecting pipes L6a, L6b, or L6c, respectively. Further, in the vicinity of the connection part between the other end of the adsorption tower connecting path L5 and the connecting pipes L7a, L7b, L7c, one of the switching valves V5d, V5e, V5f is disposed.

[0037] The adsorption towers 2A, 2B, and 2C are separation devices for obtaining a purified gas G2 by adsorbing and removing impurities contained in a raw material gas G1 with an adsorbent 6. Specifically, the adsorption towers 2A, 2B, and 2C include the adsorbent 6 disposed inside a cylindrical housing 5 and a heating unit 9 disposed so as to cover the outer peripheral surface of the housing 5.

[0038] It is preferable to use a material having heat resistance, pressure resistance, and corrosion resistance for the housing 5. The material for the housing 5 can be appropriately selected, for example, taking into consideration the internal temperature conditions, pressure conditions, adsorbent, raw material gas G1 to be used, impurities contained in the raw material gas G1, etc., but a material capable of repeatedly purifying gas under these conditions is preferable. For example, when the heating step included in the regeneration step is performed at 300°C or higher, synthetic zeolite is used as the adsorbent 6, hydrogen is used as the raw material gas G1, and the impurities in the raw material gas G1 are carbon monoxide, as will be described in detail later, it is preferable to adopt a metal such as stainless steel as the material for the housing 5.

[0039] The housing 5 may have any shape as long as it is a container into which the raw material gas G1 and the regeneration gas G3 can be introduced, the purified gas G2 and the regeneration gas G3 used for regeneration can be discharged, and the adsorbent 6 can be filled therein. An example of the shape of such a housing 5 is a cylindrical one having openings on both ends 2a and 2b.

[0040] The adsorbent 6 is for removing impurities from the source gas G1. The adsorbent 6 is filled in the space inside the casing 5. As the adsorbent 6, one or more types of adsorbents capable of selectively adsorbing impurities in the source gas G1 can be used.

[0041] The adsorbent 6 may be, for example, silica gel, zeolite, activated alumina, activated carbon, etc., but is not limited thereto, and may be appropriately selected depending on the raw gas G1 to be purified and the gas components that become impurities. The shape and dimensions of the adsorbent 6 inside the housing 5 may also be appropriately determined. Furthermore, in addition to the adsorbent 6, a catalyst (not shown) for promoting the adsorption process and the regeneration process can be placed inside the casing 5. Examples of such catalysts include palladium, copper, and ruthenium.

[0042] When regenerating the adsorbent 6, the heating unit 9 heats the casing 5 from the outside, thereby heating the adsorbent 6 and the regeneration gas G3. The heating unit 9 may be disposed so as to cover the outer peripheral surface of the housing 5, and is preferably wound spirally around the axial direction of the housing 5 as in the illustrated example.

[0043] The heating unit 9 may be provided in contact with the outer peripheral surface of the housing 5. This allows the heat generated by the heating unit 9 to be efficiently transferred to the housing 5. On the other hand, the heating unit 9 is not limited to being provided in contact with the housing 5, and may be provided in a non-contact state with the housing 5. In addition, in the heating section 9 arranged in a spiral shape around the housing 5 as in the example shown in FIG. 1, a gap is provided so that adjacent heating sections 9 do not come into contact with each other in the axial direction of the housing 5, but for example, the heating sections 9 may be in contact with each other.

[0044] The heating unit 9 is not particularly limited, but examples thereof include a sheath heater, a heating tube through which a thermal fluid flows, and an insulated Nichrome wire heating wire. The number of heating units 9 may be one or more. The heating temperature of the heating unit 9 is also not particularly limited, and may be any temperature that can heat the adsorbent 6 or the regenerated gas G3 to any desired temperature.

[0045] Although not shown in Fig. 1 etc., the adsorption towers 2A, 2B, 2C may be provided with a cooling means for cooling the adsorbent 6 arranged inside the housing 5. An example of such a cooling means is a cooling pipe configured to circulate a refrigerant inside the pipe.

[0046] In this embodiment, a heat transfer material (not shown) can be arranged to assist in the transfer of cold heat from the cooling pipe and heat heat from the heating unit 9 to the housing 5. For example, such a heat transfer material can be one that is filled to a uniform thickness in the circumferential direction of the housing 5 so as to cover the entire housing 5 and the heating unit 9 and a part of the outer circumferential surface of the cooling pipe (not shown). Such a heat transfer material can increase the heat transfer area between the cooling pipe and the heating unit 9 and the housing 5, thereby making it possible to increase the heat transfer efficiency of the cooling pipe and the heating unit 9 to the housing 5.

[0047] The material of the heat transfer material as described above may have a thermal conductivity of 1 or more, and examples of the material include heat transfer cements such as "Heat Transfer Cement HTC (registered trademark)" from Nippon Heater Co., Ltd. and "Salmon T-99 (registered trademark)" from Sakaguchi Electric Heating Co., Ltd.

[0048] The heat insulating material (not shown) is for preventing heat exchange between the adsorption towers 2A, 2B, and 2C and the outside. By providing the heat insulating material (not shown), it is possible to prevent heat from flowing out of the adsorption towers 2A, 2B, and 2C to the outside in a heating process (regeneration process) for regenerating the adsorbent 6 provided in the adsorption towers 2A, 2B, and 2C, and it is also possible to prevent heat from flowing in from the outside to the adsorption towers 2A, 2B, and 2C in a cooling process (regeneration process). This makes it possible to increase the heat conduction efficiency in the regeneration process for regenerating the adsorbent 6 in the adsorption towers 2A, 2B, and 2C.

[0049] The heat insulating material as described above can be provided, for example, so as to cover the outer peripheral surface of the housing 5. In addition, a space for installing a cooling pipe (not shown) and a heating unit 9 can be provided between the outer peripheral surface of the housing 5 and the heat insulating material. In this way, the heat insulating material is disposed so as to cover the housing 5, the cooling pipe, and the heating unit 9, and it becomes possible to prevent heat from flowing out of the adsorption towers 2A, 2B, and 2C to the outside in a heating step (regeneration step) for regenerating the adsorbent 6 in the adsorption towers 2A, 2B, and 2C, and to prevent heat from flowing in from the outside to the adsorption towers 2A, 2B, and 2C in a cooling step (regeneration step).

[0050] The heat insulating material as described above may have a thermal conductivity of less than 1, and is preferably one having a smaller thermal conductivity value. Examples of heat insulating materials include glass wool, rock wool, and the like, but are not particularly limited.

[0051] In the adsorption towers 2A, 2B, and 2C provided in the gas purification system 1 of this embodiment, examples of components contained in the impurities adsorbed and removed by the adsorbent 6 include at least one of H2O, CO2, O2, CO, and hydrocarbons.

[0052] According to the gas purification apparatus 1 of the present embodiment, by providing the adsorption tower connecting path L5 having the above-mentioned configuration, for example, when at least two of the three adsorption towers 2A, 2B, and 2C perform the regeneration process of the adsorbent 6, the regeneration gas G3 can be sequentially circulated through each of the adsorption towers performing the regeneration process. This allows the regeneration gas G3 to be efficiently used in the regeneration process without requiring a compressor or the like. In addition, since the flow rate of the regeneration gas G3 required for heating and cooling the adsorption towers 2A, 2B, and 2C can be reduced, the flow rate of the exhaust gas of the regeneration gas G3 discharged from the adsorption towers 2A, 2B, and 2C can also be reduced. Therefore, the amount of the exhaust gas of the regeneration gas G3 contained in the purified gas G2, which is the product gas, is reduced, and it is possible to increase the recovery rate as the product gas.

[0053] The gas type, flow rate, pressure, and temperature of the raw gas G1 to be purified by the gas purification apparatus 1 of this embodiment are not particularly limited, and examples thereof include air, rare gases such as He, Ar, Xe, Kr, and Ne, hydrogen, methane, hydrocarbons, etc. The gas purification apparatus 1 of this embodiment is particularly suitable for use in purifying expensive rare gases, and in gas generator applications such as hydrogen generators that have a limited amount of gas generated (amount of raw gas) and require a large amount of product gas (amount of usable gas).

[0054] In the gas purification apparatus 1 of this embodiment, the heat-resistant temperature of the switching valves V5a, V5b, V5c, V5d, V5e, and V5f provided in the adsorption tower connecting path L5 is preferably at least equal to or higher than the heating temperature of the adsorption towers 2A, 2B, and 2C. This makes it possible to prevent the switching valves from being damaged by high temperatures in the heating step (regeneration step) for regenerating the adsorbent 6 in the adsorption towers 2A, 2B, and 2C.

[0055] In addition, in this embodiment, if a gas heater is used as the heating unit, the number of heating units required can be reduced by providing the heating unit in the adsorption tower connecting path L5 connected to the adsorption towers 2A, 2B, and 2C. Here, when a heating unit is provided in the adsorption tower connecting path L5, it is necessary to use heat-resistant valves that can be used at the heating temperature of the heating unit as the switching valves V5d, V5e, and V5f connected to the other end 2b side of the adsorption towers 2A, 2B, and 2C. Even if a heating unit is not provided in the adsorption tower connecting path L5, since the regenerated gas G3 discharged from the adsorption towers 2A, 2B, and 2C is at a high temperature, as described above, it is necessary to use heat-resistant valves that can be used at the heating temperature of the adsorption towers 2A, 2B, and 2C for the switching valves V5a, V5b, and V5c through which the high-temperature regenerated gas G3 flows and the opening and closing valves V4a, V4b, and V4c.

[0056] In addition, when a pressurization step is incorporated into the operation process of the gas purification apparatus 1 of this embodiment, a pressure gauge (not shown) may be attached to each of the adsorption towers 2A, 2B, and 2C to determine the end point. The pressurization step refers to a step of increasing the pressure in each adsorption tower from the regeneration pressure to the adsorption pressure.

[0057] In addition, the number of adsorption towers provided in the gas purification apparatus 1 of this embodiment is not particularly limited as long as it is three or more, and the same effect as described above can be obtained by providing an adsorption tower connecting path (see adsorption tower connecting path L5 in FIG. 1) that enables each adsorption tower to be connected in series.

[0058] Next, an example of an operation mode of the gas purification device 1 will be described with reference to FIGS. When the gas purification apparatus 1 is operated based on the valve time chart shown in Fig. 4, for example, the operation process continues for 11 hours from the start of operation with the flows of raw material gas G1, purified gas G2, and regenerated gas G3 shown in Fig. 2. At this time, as shown in Fig. 2, raw material gas G1 is supplied only to the adsorption tower 2A from the raw material gas introduction path L1, and this adsorption tower 2A performs an adsorption process on the raw material gas G1, and the product, purified gas G2, is discharged via the product gas discharge path L2.

[0059] Meanwhile, simultaneously with the adsorption process in the adsorption tower 2A, regeneration processes are carried out in the adsorption towers 2B and 2C. Specifically, in the adsorption tower 2B, a cooling process (regeneration process) for cooling the adsorbent 6 is carried out, and in the adsorption tower 2C, a heating process (regeneration process) for heating the adsorbent 6 is carried out.

[0060] In the operation process shown in Fig. 2, the on-off valves V1a, V2a, V3b, and V4c and the switching valves V5b and V5f are opened, and the other valves are closed. That is, in the operation process shown in Fig. 2, a part of the regeneration gas G3 is introduced from the other end 2b of the adsorption tower 2B through the regeneration gas introduction path L3, and the exhaust gas of the regeneration gas G3 discharged from one end 2a of the adsorption tower 2B is introduced from the other end 2b through the adsorption tower connecting path L5 to the adsorption tower 3C. Then, the exhaust gas of the regeneration gas G3 discharged from one end 2a of the adsorption tower 3C is discharged to the outside of the adsorption tower 3C through the regeneration gas discharge path L4.

[0061] In the operation process shown in FIG. 2, only the heating unit 9 of the adsorption tower 2C performing the heating step (regeneration step) is turned on.

[0062] Next, from 11 hours to 12 hours after the start of operation, the operation process is carried out with the flows of raw material gas G1, purified gas G2, and regenerated gas G3 shown in Fig. 3. At this time, as shown in Fig. 3, raw material gas G1 continues to be supplied only to the adsorption tower 2A from the raw material gas introduction path L1, and this adsorption tower 2A carries out an adsorption process on the raw material gas G1, whereby the product, purified gas G2, is discharged via the product gas discharge path L2.

[0063] Meanwhile, the regeneration process continues in the adsorption towers 2B and 2C as well. However, in the operating process shown in FIG. 3, unlike the operating process shown in FIG. 2, the adsorption tower 2B goes into standby mode and the pressurization process is carried out in the adsorption tower 2C.

[0064] In the operation process shown in Fig. 3, the on-off valves V1a, V2a, and V3b are opened, and the other valves are closed. In the operation process shown in Fig. 3, the heating unit 9 provided in the adsorption tower 2C is also turned off, as in the other adsorption towers 2A and 2B.

[0065] When performing operations using the gas purification apparatus 1 of this embodiment, for example, the above-mentioned operating process can be performed in rotation for the three adsorption towers 2A, 2B, and 2C based on the valve time chart shown in FIG.

[0066] [Gas purification method] Next, the gas purification method of this embodiment will be described in detail with reference to the same drawings, taking as an example an operation using the gas purification apparatus 1 of this embodiment described above.

[0067] The gas purification method of this embodiment uses at least three adsorption towers 2A, 2B, and 2C filled with an adsorbent 6 that adsorbs impurities in a raw material gas G1, and uses the TSA method to adsorb and remove impurities from the raw material gas G1 to obtain a product purified gas G2. That is, the gas purification method of this embodiment repeatedly performs an adsorption step (1) in which impurities in a raw material gas G1 are adsorbed and removed in the adsorption towers 2A, 2B, and 2C, and a regeneration step (2) in which the impurities adsorbed in the adsorption towers 2A, 2B, and 2C are released from the adsorption towers 2A, 2B, and 2C by heating the adsorption towers 2A, 2B, and 2C. In addition, in this embodiment, at least one adsorption tower 2A among the three adsorption towers 2A, 2B, and 2C performs the adsorption step (1), and gas purification is performed while using a part of the purified gas G2 obtained by removing impurities from the raw material gas G1 and discharged from the adsorption tower 2A in the adsorption step (1) as a regeneration gas G3 for purging the adsorption towers 2B and 2C in the regeneration step (2).

[0068] The gas purification method of the present embodiment is a method in which, when at least two of the three adsorption towers 2A, 2B, and 2C perform the regeneration step (2), the regeneration gas G3 is sequentially circulated through each of the adsorption towers 2B, 2C performing the regeneration step (2). That is, in this embodiment, an example will be described in which the adsorption step (1) is carried out in one adsorption tower 2A, and simultaneously, the regeneration step (2) is carried out in two adsorption towers 2B and 2C.

[0069] (Adsorption process (1)) First, in the adsorption step (1), as described in the description of the gas purification apparatus 1 of this embodiment, the on-off valves V1a, V2a, V3b, and V4c and the switching valves V5b and V5f are opened, and the other valves are closed. That is, as in the operation process shown in Fig. 2, the raw material gas G1 supplied from the raw material gas introduction path L1 is supplied to the adsorption tower 2A via the connection pipe L6a.

[0070] Then, impurities are adsorbed and removed from the raw gas G1 by the adsorbent 6 provided in the adsorption tower 2A to generate a purified gas (product gas) G2. Thereafter, the generated purified gas G2 is discharged to the outside as a product gas via the connection pipe L7a and the product gas discharge path L2.

[0071] In the adsorption step (1), the components contained in the impurities adsorbed and removed by the adsorbent, i.e., the target for removal in the gas purification method of the present embodiment, are not particularly limited, but may be, for example, at least one of HO, CO, O, CO, and hydrocarbons.

[0072] The other adsorption towers 2B and 2C have the same configuration as the adsorption tower 2A, and therefore can obtain the same effects as the adsorption tower 2A in the adsorption step (1).

[0073] (Regeneration process (2)) In the regeneration process (2), as described above, the on-off valves V1a, V2a, V3b, and V4c and the switching valves V5b and V5f are opened, and the other valves are closed, so that the regeneration process (2) is carried out in the adsorption towers 2B and 2C simultaneously with the adsorption process (1) carried out in the adsorption tower 2A.

[0074] The regeneration step (2) in the example described in this embodiment includes at least a heating step (2-1) for heating the adsorption tower 2C, and a cooling step (2-2) for cooling the adsorption tower 2C after the heating step (2-1) to a temperature at which the adsorption step (1) can be performed. More specifically, when one of the three adsorption towers 2A, 2B, and 2C performs the heating step (2-1) and one of the adsorption towers 2B performs the cooling step (2-2), the regeneration gas G3 is introduced into the adsorption tower 2B performing the cooling step (2-2). At the same time, the regeneration gas G3 discharged from the adsorption tower 2B performing the cooling step (2-2) is introduced into the adsorption tower 2C performing the heating step (2-1).

[0075] That is, in the regeneration step (2), while the purified gas G2 is being discharged to the outside from the product gas discharge path L2, a portion of the purified gas G2 is introduced into the adsorption tower 2B as the regeneration gas G3 via the regeneration gas introduction path L3 and the connecting pipe L7b, and a portion of the purified gas G2 is introduced into the adsorption tower 2C as the regeneration gas G3 via the regeneration gas introduction path L3 and the connecting pipe L7c.

[0076] At this time, in the adsorption tower 2C, the heating unit 9 is started to heat the housing 5, thereby indirectly (auxiliarily) heating the regeneration gas G3 and the adsorbent 6 in the housing 5. Meanwhile, in the adsorption tower 2B, the adsorbent 6 in the housing 5 is cooled by introducing the regeneration gas G3 taken out from the regeneration gas introduction path L3 into the adsorption tower 2B.

[0077] In this embodiment, in the regeneration step (2), the exhaust gas of the regeneration gas G3 discharged from one end 2a of the adsorption tower 2B is introduced into the adsorption tower 2C from the other end 2b via the connecting pipe L6b, the adsorption tower connecting path L5, and the connecting pipe L7C.

[0078] As described above, the adsorbent 6 in the adsorption tower 2C (housing 5) is heated to approximately 100 to 400° C. using the regeneration gas G3 and the heating unit 9, thereby desorbing impurities from the adsorbent 6. At this time, the impurities desorbed from the adsorbent 6 are mixed with the regeneration gas G3 and are discharged to the outside via the connection pipe L6c and the regeneration gas discharge path L4.

[0079] After the impurities adsorbed by the adsorbent 6 have been sufficiently removed in the heating step (2-1), the operation of the heating unit 9 is stopped, the on-off valves V1a, V2a, and V3b are opened, and the other valves are closed. As a result, as in the operating process shown in Figure 3, the raw material gas G1 continues to be supplied only to the adsorption tower 2A from the raw material gas inlet path L1, and this adsorption tower 2A performs the adsorption process (1) on the raw material gas G1, thereby continuously discharging the product, refined gas G2, via the product gas discharge path L2.

[0080] Meanwhile, the regeneration process (2) continues in the adsorption towers 2B and 2C as well. However, unlike the operation process shown in FIG. 2, the adsorption tower 2B is in a standby state, and the pressurization process is carried out in the adsorption tower 2C.

[0081] In the gas purification method of the present embodiment, for example, the above-described operation process can be performed in rotation for the three adsorption towers 2A, 2B, and 2C.

[0082] According to the gas purification method of this embodiment, when at least two adsorption towers 2B, 2C perform the regeneration step (2), the regeneration gas G3 is sequentially circulated through each of the adsorption towers 2B, 2C, thereby reducing the flow rate of the regeneration gas G3 required for heating and cooling the adsorption towers 2B, 2C, and also reducing the flow rate of the exhaust gas of the regeneration gas G3 discharged from the adsorption towers 2B, 2C in the regeneration step (2). This reduces the amount of the exhaust gas of the regeneration gas G3 contained in the purified gas G2, making it possible to increase the recovery rate as a product gas.

[0083] In the gas purification method of this embodiment, it is preferable to cool the temperature of the regeneration gas G3 discharged from the adsorption tower 2B in which the cooling step (2-2) is being performed to 150°C or less before introducing the regeneration gas G3 into the adsorption tower C in which the heating step (2-1) is being performed.

[0084] <Second embodiment> Next, a gas purification method and a gas purification apparatus according to a second embodiment of the present invention will be described below. In the following description, the same components (or similar components) as those of the gas purification apparatus 1 of the first embodiment described above will be denoted by the same reference numerals and detailed description thereof may be omitted. In the following description, detailed description of the same procedures and conditions as those of the gas purification method of the first embodiment may be omitted.

[0085] FIG. 5 is a system diagram showing an overall schematic configuration of a gas purification apparatus 1A according to the second embodiment. FIG. 7 is a valve time chart showing the opening and closing operations of the valves for controlling the flows of the raw material gas G1, the purified gas G2, and the regenerated gas G3 in the gas purification apparatus 1A shown in FIG.

[0086] The gas purification apparatus 1A of the second embodiment shown in FIG. 5 is similar to the gas purification apparatus 1 of the first embodiment shown in FIG. 1 in that it includes adsorption towers 2A, 2B, and 2C, a raw material gas inlet path L1, a product gas outlet path L2, a regeneration gas inlet path L3, and a regeneration gas outlet path L4. On the other hand, the gas purification apparatus 1A of the second embodiment differs from the gas purification apparatus 1 of the first embodiment in that it is provided with adsorption tower connecting paths (adsorption tower connecting piping) L5A1, L5A2, L5A3 that connect one end 2a of any one of the adsorption towers 2A, 2B, 2C to the other end 2b of the other adsorption tower via connecting piping L6a, L6b, L6c or connecting piping L7a, L7b, L7c.

[0087] That is, in the gas purification apparatus 1A shown in FIG. 5, one end 2a of the adsorption tower 2C and the other end 2b of the adsorption tower 2A are connected by an adsorption tower connecting path L5A1 via connection pipes L6c and L7a, respectively. One end 2a of the adsorption tower 2A and the other end 2b of the adsorption tower 2B are connected by an adsorption tower connecting path L5A2 via connecting pipes L6a and L7b, respectively. Moreover, one end 2a of the adsorption tower 2B and the other end 2b of the adsorption tower 2c are connected by an adsorption tower connecting path L5A3 via connecting pipes L6b and L7c, respectively.

[0088] In operating the gas purification apparatus 1A having the adsorption tower connecting paths L5A1, L5A2, and L5A3 as shown in Fig. 5, each operation process can be performed based on the valve timing chart shown in Fig. 7. That is, in the gas purification apparatus 1A of the second embodiment, as in the case of the gas purification apparatus 1 of the first embodiment, the switching valves V5a, V5b, and V5c provided in the adsorption tower connecting paths L5A1, L5A2, and L5A3 can be opened and closed at a predetermined timing. As a result, in the gas purification apparatus 1A, when at least two of the three adsorption towers 2A, 2B, and 2C perform the regeneration step (2), it is possible to perform an operation process in which the regeneration gas G3 is sequentially circulated through each of the adsorption towers 2B and 2C performing the regeneration step (2).

[0089] In the operation of the gas purification method using the gas purification apparatus 1A of this embodiment, immediately after the completion of the heating step (2-1) provided in the regeneration step (2) and the start of the cooling step (2-2), high-temperature regeneration gas G3 (gas having a temperature corresponding to the heating temperature in the adsorption towers) is discharged from the outlet side of the adsorption towers 2A, 2B, and 2C. For this reason, in the gas purification apparatus 1A of this embodiment, the on-off valves V4a, V4a, and V4b and the switching valves V5a, V5b, and V5c shown in Fig. 5 must be heat-resistant valves that can be used at the heating temperatures of the adsorption towers 2A, 2B, and 2C.

[0090] According to the gas purification apparatus 1A of the present embodiment, by providing the adsorption tower connecting paths L5A1, L5A2, and L5A3 having the above-mentioned configuration, when at least two of the three adsorption towers 2A, 2B, and 2C perform the regeneration step (2) of the adsorbent 6, the regeneration gas G3 can be sequentially circulated to each of the adsorption towers performing the regeneration step (2), as in the case of the gas purification apparatus 1 of the first embodiment. This allows the regeneration gas G3 to be efficiently used in the regeneration step (2) without the need for a compressor or the like. Also, as in the above, the flow rate of the regeneration gas G3 required for heating and cooling the adsorption towers 2A, 2B, and 2C can be reduced, so that the flow rate of the exhaust gas of the regeneration gas G3 discharged from the adsorption towers 2A, 2B, and 2C can also be reduced. Therefore, the amount of exhaust gas of the regeneration gas G3 contained in the purified gas G2, which is the product gas, is reduced, and it is possible to increase the recovery rate as the product gas.

[0091] <Third embodiment> Next, a gas purification method and a gas purification apparatus according to a third embodiment of the present invention will be described below. In the following description, the same or similar configurations as those of the gas purification apparatuses 1 and 1A of the first and second embodiments described above will be denoted by the same reference numerals and detailed description thereof may be omitted. In the following description, detailed description of the same procedures and conditions as those of the gas purification methods of the first and second embodiments may be omitted.

[0092] FIG. 6 is a system diagram showing an overall schematic configuration of a gas purification apparatus 1B according to the third embodiment. FIG. 7 is a valve time chart showing the opening and closing operations of the valves for controlling the flows of the raw material gas G1, the purified gas G2, and the regenerated gas G3 in the gas purification apparatus 1B shown in FIG.

[0093] A gas purification apparatus 1B of the third embodiment shown in Fig. 6 is similar to the gas purification apparatus 1A of the second embodiment shown in Fig. 5 in that it includes adsorption towers 2A, 2B, and 2C, a raw material gas introduction path L1, a product gas discharge path L2, a regeneration gas introduction path L3, and a regeneration gas discharge path L4, and further includes adsorption tower connection paths L5A1, L5A2, and L5A3 that connect one end 2a of any one of the adsorption towers 2A, 2B, and 2C to the other end 2b of the other adsorption tower. The gas purification apparatus 1B of the third embodiment shown in Fig. 6 is also similar to the gas purification apparatus 1A of the second embodiment shown in Fig. 5 in that each operation process can be performed based on, for example, the valve timing chart shown in Fig. 7. On the other hand, the gas purification apparatus 1B of the third embodiment differs from the gas purification apparatus 1A of the second embodiment in that heat exchangers 7a, 7b, and 7c for cooling the regenerated gas G3 flowing through the adsorption tower connecting paths L5A1, L5A2, and L5A3 are provided on the primary sides of the switching valves V5a, V5b, and V5c provided in the adsorption tower connecting paths L5A1, L5A2, and L5A3, respectively.

[0094] As the heat exchangers 7a, 7b, and 7c shown in FIG. 3, for example, fin tube, turbinent tube, or plate fin type heat exchangers can be used, but the type of heat exchanger and the cooling method (air cooling or water cooling), etc., are not particularly limited.

[0095] In the operation of the gas purification method using the gas purification apparatus 1B of this embodiment, after the heating step (2-1) in the regeneration step (2) is completed, the temperature of the high-temperature regeneration gas G3 discharged from the outlet side of the adsorption towers 2A, 2B, 2C immediately after the start of the cooling step (2-2) is preferably lowered to 150° C. or lower by the heat exchangers 7a, 7b, 7c, more preferably to 80° C. or lower. This is because, when the outlet temperatures of the heat exchangers 7a, 7b, 7c exceed 150° C., it is necessary to use expensive all-metal diaphragm valves (e.g., FWB-71 series manufactured by Fujikin Co., Ltd.) for the switching valves V5a, V5b, V5c disposed on the outlet sides of the heat exchangers 7a, 7b, 7c.

[0096] On the other hand, by cooling the regenerated gas G3 discharged from the adsorption towers 2A, 2B, and 2C to a temperature of 150°C or less by the heat exchangers 7a, 7b, and 7c, it is possible to use inexpensive valves such as metal diaphragm valves using polyimide or PFA as the sheet material (e.g., FPR-ND-71-6.35-PI manufactured by Fujikin Co., Ltd.).

[0097] Furthermore, when the regenerated gas G3 discharged from the adsorption towers 2A, 2B, and 2C is cooled to a temperature of 80°C or less by the heat exchangers 7a, 7b, and 7c, a cheaper valve such as a general-purpose metal diaphragm valve (e.g., FPR-ND-71-6.35 manufactured by Fujikin Co., Ltd.) can be used.

[0098] Incidentally, the all-metal diaphragm described above is not only expensive, but also, due to its structural characteristics, even the inflow of a small amount of dust is likely to cause an internal leak through which gas flows even when the valve is closed, leading to malfunctions in the gas purification device, so it is desirable to avoid using such a diaphragm.

[0099] <Fourth embodiment> Next, a gas purification method and a gas purification apparatus according to a fourth embodiment of the present invention will be described below. In the following description, the same or similar configurations as those of the gas purification apparatuses 1, 1A, and 1B of the first to third embodiments described above will be denoted by the same reference numerals and detailed description thereof may be omitted. In the following description, detailed description of the same procedures and conditions as those of the gas purification methods of the first to third embodiments may be omitted.

[0100] FIG. 8 is a system diagram showing an overall schematic configuration of a gas purification apparatus 1C according to the fourth embodiment.

[0101] A gas purification apparatus 1C of the fourth embodiment shown in Fig. 8 is similar to the gas purification apparatus 1A of the second embodiment shown in Fig. 5 in that it includes adsorption towers 2A, 2B, and 2C, a raw material gas introduction path L1, a product gas discharge path L2, a regeneration gas introduction path L3, and a regeneration gas discharge path L4, and further includes adsorption tower connection paths L5A1, L5A2, and L5A3 that connect one end 2a of any one of the adsorption towers 2A, 2B, and 2C to the other end 2b of the other adsorption tower. The gas purification apparatus 1C of the fourth embodiment shown in Fig. 8 is also similar to the gas purification apparatus 1A of the second embodiment shown in Fig. 5 in that each operation process can be performed based on, for example, the valve timing chart shown in Fig. 7.

[0102] On the other hand, the gas purification apparatus 1C of the fourth embodiment differs from the gas purification apparatus 1A of the second embodiment in that heat exchangers 71a, 71b, and 71c for cooling the regeneration gas G3 circulating through the regeneration gas discharge path L4 are provided between the adsorption towers 2A, 2B, and 2C and the on-off valves V4a, V4b, and V4c provided in the regeneration gas discharge path L4. Furthermore, the gas purification apparatus 1C of the fourth embodiment differs from the gas purification apparatus 1A of the second embodiment in that drain traps 8a, 8b, and 8c are provided inside the heat exchangers 71a, 71b, and 71c provided in the regeneration gas discharge path L4, or in the regeneration gas discharge path L4 on the outlet side of these heat exchangers 71a, 71b, and 71c. Fig. 8 shows an example in which the drain traps 8a, 8b, and 8c are provided at the ends of three drain pipes L41, which are intake pipes from the regeneration gas discharge path L4.

[0103] According to the gas purification apparatus 1C of the present embodiment, first, the heat exchangers 71a, 71b, and 71c are provided in the regeneration gas discharge path L4 between the adsorption towers 2A, 2B, and 2C and the on-off valves V4a, V4b, and V4c, respectively, so that, as described above, there is no need to use expensive heat-resistant valves for the on-off valves V4a, V4b, and V4c. That is, the regeneration gas G3 discharged at high temperature from the adsorption towers 2A, 2B, and 2C is cooled by the heat exchangers 71a, 71b, and 71c, so that it is possible to use inexpensive general-purpose valves for the on-off valves V4a, V4b, and V4c, thereby reducing the cost of the apparatus.

[0104] In addition, according to the gas purification apparatus 1C of this embodiment, the drain traps 8a, 8b, and 8c of the above-mentioned configuration are provided, and thus the following effects can be obtained. That is, the regeneration gas G3 discharged from the adsorption tower that has undergone the heating step (2-1) contains moisture desorbed from the adsorbent 6, and is cooled by the heat exchangers 71a, 71b, and 71c to generate a large amount of drain. If a large amount of such drain is generated, there is a risk that the regeneration gas discharge path L4 will be clogged by the drain. On the other hand, by adopting a configuration in which the drain traps 8a, 8b, and 8c are provided as in the gas purification apparatus 1C of this embodiment, it is possible to prevent the above-mentioned blockage of the regeneration gas discharge path L4.

[0105] <Action and effect> As described above, according to the gas purification method using the gas purification apparatuses 1, 1A, 1B, and 1C of the present embodiment, when at least two of the three adsorption towers 2A, 2B, and 2C perform the regeneration step (2), the regeneration gas G3 is sequentially circulated through each of the adsorption towers 2B and 2C performing the regeneration step (2). By adopting such a method, the flow rate of the regeneration gas G3 required for heating and cooling the adsorption towers 2A, 2B, and 2C can be reduced, and the flow rate of the exhaust gas of the regeneration gas G3 discharged from the adsorption towers 2A, 2B, and 2C in the regeneration step (2) can also be reduced. As a result, the amount of the exhaust gas of the regeneration gas G3 contained in the purified gas G2 can be reduced, and the recovery rate as a product gas can be increased.

[0106] In addition, according to the gas purification device of the present invention, an adsorption tower connecting path L5 is provided between each of the three adsorption towers 2A, 2B, 2C, connecting one end 2a to which the regenerated gas discharge path L4 is connected and the other end 2b to which the regenerated gas introduction path L3 is connected, and a configuration is adopted in which the adsorption tower connecting path L5 is provided with switching valves V5a, V5b, V5c. By adopting such a configuration, as in the above, the flow rate of the regenerated gas G3 required for heating and cooling the adsorption towers 2A, 2B, 2C can be reduced, and the flow rate of the exhaust gas of the regenerated gas G3 discharged from the adsorption towers 2A, 2B, 2C can also be reduced. In addition, the regenerated gas G3 can be efficiently used without requiring a compressor (booster) or the like. As a result, the amount of the exhaust gas of the regenerated gas G3 contained in the purified gas G2 can be reduced, and the gas purification devices 1, 1A, 1B, 1C that can increase the recovery rate as a product gas can be realized.

[0107] In addition, the regeneration gas G3, which is heated by removing heat from the adsorbent 6 while ventilating the adsorption tower undergoing the cooling step (2-2) included in the regeneration step (2), is ventilated through the adsorption tower undergoing the heating step (2-1). This reduces the load on the heating section 9 during the heating step (2-1) and also shortens the heating time during the heating step (2-1).

[0108] <Other forms> Although an example of the gas purification method and gas purification apparatus according to the present invention has been described above by way of an embodiment, the present invention is not limited to the above embodiment. Each configuration and combination thereof in the above embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention.

[0109] For example, in each of the above embodiments, the gas purification apparatuses 1, 1A, 1B, and 1C each having three adsorption towers 2A, 2B, and 2C are exemplified, but the number of adsorption towers to be installed is not limited to this, and it is also possible to adopt an apparatus configuration and method including, for example, four or more adsorption towers. EXAMPLES

[0110] The gas purification method and gas purification apparatus of the present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and can be modified as appropriate within the scope of the present invention.

[0111] <Refining conditions, regeneration conditions, and configuration of gas purification equipment> In this embodiment, the effects of the present invention were verified by purifying hydrogen using a gas purification apparatus 1 having a configuration according to the present invention, which employs a three-tower switching TSA method as shown in FIG. 1 and has an adsorption tower connecting path L5 (embodiment). In addition, in this example, as a comparative example to the three-tower switching gas purification apparatus 1 shown in Figure 1, a conventional gas purification apparatus having a two-tower switching type as disclosed in JP 2020-65984 A and no adsorption tower connecting path was prepared and evaluated under similar conditions (comparative example).

[0112] In this example, in order to obtain purified hydrogen, a raw material gas consisting mainly of hydrogen gas and containing approximately 2800 ppm of moisture as an impurity was used, and the amount of regeneration gas contained in the purified gas was compared between the example and the comparative example.

[0113] [Gas purification / regeneration conditions] The raw material gas compositions and gas purification / regeneration conditions in the examples and comparative examples are listed below. (1) Raw gas composition: H2+H2O (2) H2O concentration: 2800 ppm (component to be removed) (3)Flow rate: 100Nm3 / h (4) Pressure: 800kPaG (5) Temperature: 25℃ (6) Adsorbent: Zeolite (synthetic) (7) Regeneration temperature: 300℃ (8) Regeneration pressure: atmospheric pressure

[0114] In both the examples and the comparative examples, the adsorption tower used had an inner cylinder (housing) made of SUS304 (size: Sch10S of 80A) and a height of 1330 mm. As the adsorbent, synthetic zeolite was used as described above, and the packing height (height of the adsorbent layer) was set to 1240 mm.

[0115] [Operation procedure] (Example) In the examples, the gas purification apparatus of the example, which was of a three-tower switching type, was used to adsorb impurities such as moisture from the raw material gas in the following manner, and hydrogen was obtained as purified gas. First, based on the valve time chart shown in FIG. 4, in the operation process shown in FIG. 2, raw gas G1 was supplied from raw gas introduction path L1 to adsorption tower 2A to carry out the adsorption process, and purified gas G2 was discharged via product gas discharge path L2.

[0116] In addition, simultaneously with the adsorption step in the adsorption tower 2A, the regeneration step was performed in the adsorption towers 2B and 2C. At this time, the adsorption tower 2B performed a cooling step (regeneration step) for cooling the adsorbent 6, and the adsorption tower 2C performed a heating step (regeneration step) for heating the adsorbent 6. That is, a part of the regeneration gas G3 was introduced from the other end 2b side of the adsorption tower 2B through the regeneration gas introduction path L3, and the exhaust gas of the regeneration gas G3 discharged from the one end 2a side of the adsorption tower 2B was introduced from the other end 2b side through the adsorption tower connecting path L5 into the adsorption tower 3C. In addition, the exhaust gas of the regeneration gas G3 discharged from the one end 2a side of the adsorption tower 3C was discharged to the outside of the adsorption tower 3C through the regeneration gas discharge path L4. In addition, in this operation process, only the heating unit 9 of the adsorption tower 2C performing the heating step (regeneration step) was turned on.

[0117] Next, in the operation process shown in FIG. 3, the adsorption step was subsequently carried out in the adsorption tower 2A, the adsorption tower 2B was placed on standby, and the pressurization step was carried out in the adsorption tower 2C. In this embodiment, the above-mentioned operation process was carried out in rotation for the three adsorption towers 2A, 2B, and 2C based on the valve time chart shown in FIG.

[0118] (Comparative Example) Using a two-tower switching type gas purification apparatus of the comparative example, impurities such as moisture were adsorbed from the raw material gas in the following manner, and hydrogen was obtained as purified gas. First, the raw gas was continuously sent into one of the adsorption towers to produce a purified gas, and in the other adsorption tower, a part of the purified gas obtained from one of the adsorption towers was used as a regeneration gas and circulated into the other adsorption tower. At this time, the other adsorption tower was heated by a heating unit.

[0119] Next, in one of the adsorption towers, the raw gas was purified in one of the adsorption towers under the same conditions as described above, and in the other adsorption tower, a portion of the purified gas obtained in one of the adsorption towers was circulated as a regeneration gas into the other adsorption tower to cool the other adsorption tower.

[0120] Next, the above steps were carried out in rotation by replacing one adsorption tower with the other adsorption tower.

[0121] <Evaluation Results> Table 1 below shows the operating processes of the two-tower switching system (Comparative Example) and the three-tower switching system (Example), as well as the comparison results of the amount of regeneration gas contained in the purified gas (product gas) in these Examples and Comparative Examples. The recovery rate shown in Table 1 below is a value expressed by the following formula: (amount of raw material gas supplied per cycle)-(amount of exhaust regeneration gas per cycle) / (amount of raw material gas supplied per cycle)

[0122] [Table 1]

[0123] As shown in Table 1, in the comparative example using a two-tower switching type gas purification apparatus having a conventional configuration, the recovery rate of the purified gas, calculated by subtracting the regenerated gas from the purified gas, was 96.7%. In contrast, in an example using the configuration according to the present invention, i.e., a three-tower switching TSA method and a gas purification apparatus 1 having an adsorption tower connecting path L5, the recovery rate of the purified gas, calculated by subtracting the regenerated gas from the purified gas, was 98.2%, which was an improved recovery rate compared to the comparative example.

[0124] From the results of this example as described above, it became clear that, by applying the present invention, the flow rate of the regeneration gas required for heating and cooling the adsorption tower can be reduced, and the flow rate of the exhaust gas of the regeneration gas discharged from the adsorption tower in the regeneration process can also be reduced, so that the amount of exhaust gas of the regeneration gas contained in the purified gas can be reduced and the recovery rate of the purified gas as the product can be increased. [Industrial Applicability]

[0125] The gas purification method and gas purification apparatus of the present invention can efficiently utilize regeneration gas without requiring a compressor, etc., and can reduce the amount of exhaust gas from the regeneration gas and increase the recovery rate of the product gas. Therefore, the present invention is extremely suitable for applications to gas generators, such as, for example, purification of rare gases, which are particularly expensive, and hydrogen generators, which have a limited amount of gas generation (amount of raw gas) and require a large amount of product gas (amount of usable gas). [Explanation of symbols]

[0126] 1, 1A, 1B, 1C...Gas purification equipment 2A, 2B, 2C…Adsorption tower 2a…one end 2b...other end 5. Housing 6…Adsorbent 9...Heating section L1: Raw material gas introduction path (raw material gas introduction piping) L2: Product gas outlet route (product gas outlet piping) L3: Regenerated gas introduction path (regenerated gas introduction piping) L4: Regenerated gas discharge route (regenerated gas exhaust piping) L5, L5A1, L5A2, L5A3...Adsorption tower connection route (adsorption tower connection piping) L41…Drain pipe L6a, L6b, L6c, L7a, L7b, L7c...Connection pipes V1a, V1b, V1c, V2a, V2b, V2c, V3a, V3b, V3c, V4a, V4b, V4c...Opening and closing valves V5a, V5b, V5c, V5d, V5e, V5f...Switching valve 7a,7b,7c,71a,71b,71c...Heat exchanger 8a, 8b, 8c...Drain trap NV1…Regeneration gas flow rate adjustment valve G1: Raw material gas G2: Refined gas G3…Regenerated gas

Claims

1. A gas purification method using at least three adsorption towers filled with an adsorbent that adsorbs impurities in a raw material gas, repeatedly carrying out an adsorption step of adsorbing and removing the impurities in the raw material gas in the adsorption towers by a TSA (Thermal Swing Adsorption) system, and a regeneration step of heating the adsorption towers to remove the impurities adsorbed in the adsorption towers from the adsorption towers, wherein at least one of the three adsorption towers carries out the adsorption step, and a portion of the purified gas obtained by removing the impurities from the raw material gas and discharged from the adsorption towers in the adsorption step is used as a regeneration gas for purging the adsorption towers in the regeneration step, a regeneration step of at least two of the three adsorption towers, the regeneration gas being sequentially circulated through each of the adsorption towers performing the regeneration step.

2. the regeneration step includes at least a heating step of heating the adsorption tower, and a cooling step of cooling the adsorption tower after the heating step to a temperature at which the adsorption step can be performed, 2. The gas purification method according to claim 1, wherein, when at least one of the three adsorption towers performs the heating step and at least one of the adsorption towers performs the cooling step, the regeneration gas is introduced into the adsorption tower performing the cooling step, and the regeneration gas discharged from the adsorption tower performing the cooling step is introduced into the adsorption tower performing the heating step.

3. 3. The gas purification method according to claim 1, wherein the temperature of the regeneration gas discharged from the adsorption tower undergoing the cooling step is cooled to 150° C. or less before being introduced into the adsorption tower undergoing the heating step.

4. The components contained in the impurities to be adsorbed and removed by the adsorbent are at least H ２ O, CO ２ , O ２ 3. The gas purification method according to claim 1, wherein the gas is any one of CO and hydrocarbons.

5. A gas purification apparatus for producing a purified gas by adsorbing and removing impurities from a raw material gas, comprising: at least three adsorption towers filled with an adsorbent for adsorbing and removing the impurities from the raw material gas; a raw material gas inlet pipe for introducing the raw material gas into the adsorption tower, and a regeneration gas outlet pipe for discharging the regeneration gas introduced into the adsorption tower from the adsorption tower, each of which is connected to one end of the adsorption tower; a product gas outlet pipe for discharging the refined gas from the adsorption tower and a regeneration gas inlet pipe for introducing the regeneration gas into the adsorption tower, the product gas outlet pipe and the regeneration gas inlet pipe being connected to the other end of the adsorption tower, on-off valves provided at one end or the other end of the adsorption tower in the raw gas inlet pipe, the regeneration gas exhaust pipe, the product gas outlet pipe, and the regeneration gas inlet pipe, respectively; a heating unit provided in the adsorption tower for heating the adsorbent or the regeneration gas; a gas purification apparatus characterized in that an adsorption tower connecting pipe is provided between each of the three adsorption towers, the adsorption tower connecting pipe connecting one end of the adsorption tower to which the regeneration gas exhaust pipe is connected and the other end of the adsorption tower to which the regeneration gas introduction pipe is connected, and a switching valve is provided on the adsorption tower connecting pipe.

6. 6. The gas purification system according to claim 5, wherein the adsorption tower connecting pipe is provided so that all three of the adsorption towers are connected in an annular shape.

7. 7. The gas purification system according to claim 5, wherein the heat-resistant temperature of the switching valve provided in the adsorption tower connecting pipe is at least equal to or higher than the heating temperature of the adsorption tower.

8. 7. The gas purification apparatus according to claim 5, wherein a heat exchanger for cooling the regenerated gas flowing through the adsorption tower connecting pipe is provided on a primary side of the switching valve provided in the adsorption tower connecting pipe.

9. 7. The gas purification apparatus according to claim 5, further comprising a heat exchanger for cooling the gas flowing through the regeneration gas exhaust pipe, the heat exchanger being provided between the adsorption tower and an opening / closing valve provided in the regeneration gas exhaust pipe.

10. 10. The gas purification apparatus according to claim 9, further comprising a drain trap provided inside the heat exchanger provided in the regeneration gas discharge pipe or in the regeneration gas discharge pipe on the outlet side of the heat exchanger.

11. The components contained in the impurities to be adsorbed and removed by the adsorbent are at least H ２ O, CO ２ , O ２ 7. The gas purification apparatus according to claim 5, wherein the gas is any one of CO and hydrocarbons.

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