Gas purification method and gas purification device

Abstract

The present invention provides a gas purification method and a gas purification device with which it is possible to efficiently utilize regeneration gas without the need for a compressor or the like, and to reduce the amount of exhaust gas from regeneration gas and improve the product gas recovery rate. The present invention provides a gas purification method in which an adsorption step for adsorbing and removing impurities in a raw material gas (G1) using three adsorption towers (2A, 2B, 2C) and a regeneration step for heating the adsorption towers (2A, 2B, 2C) to separate impurities from the adsorption towers (2A, 2B, 2C) are repeatedly performed. At least one of the adsorption towers (2A, 2B, 2C) performs the adsorption step, and at least part of a purified gas G2 obtained by removing impurities from the raw material gas (G1) and discharged from the adsorption towers in the adsorption step is used as a regeneration gas (G3) for purging the adsorption towers (2A, 2B, 2C) in the regeneration step. When at least two adsorption towers (2B, 2C) among the three adsorption towers (2A, 2B, 2C) perform the regeneration step, the regeneration gas (G3) is sequentially circulated to each adsorption tower (2B, 2C) that performs the regeneration step.

Description

Gas purification method and gas purification device

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

[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). Generally, a gas purification apparatus employing the TSA method is widely configured to have two adsorption towers for adsorbing impurities in order to continuously supply the product gas, and to alternately operate the two adsorption towers between a purification step (impurity adsorption) and a regeneration step (impurity desorption).

[0003] In a typical gas purification system using the TSA method and having a two-column switching configuration, when regenerating the adsorbent in the adsorption tower after gas purification, either a portion 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 to desorb the target substances. The adsorbent is heated, for example, by a regeneration gas heated by a gas heater or by heat input from a jacket heater or the like attached to the adsorption tower. Because activated carbon and zeolite, which are commonly used adsorbents, have low thermal conductivity, it is difficult to uniformly heat the adsorbent solely by external heating such as a jacket heater. 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. The regeneration gas flow rate required for adsorbent regeneration, i.e., 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 adsorbed target substances, the amount of heat required for desorption, the heat capacity of the adsorption tower and the adsorbent, and other factors.

[0004] As described above, when a portion of the product gas is used as the regeneration gas, the regeneration gas directly leads to a loss of product gas. Furthermore, even if a separate gas that is non-adsorbable to the adsorbent is prepared and used as the regeneration gas, this not only increases utility costs, but also creates the problem that if the non-adsorbable gas remains in the adsorption tower, it becomes an impurity component in the product gas, reducing the purity of the product gas. Therefore, 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 systems that use the TSA method.

[0005] On the other hand, in the case of a two-column switching gas purification system (TSA system) as described above, the time that can be allocated to the regeneration process depends on the amount of adsorbent packed in the adsorption column, i.e., the time of the adsorption process. Therefore, for example, if 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 that needs to be removed during cooling increases, which may result in insufficient cooling of the adsorbent. For this reason, in a gas purification system (TSA system) with a two-column switching configuration, there is a limit to the improvement in recovery rate by reducing the flow rate of the regeneration gas.

[0006] Here, for example, a technique described in Patent Document 1 is known as a means for improving the recovery rate of product gas in a gas purification apparatus. 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 regeneration gas exhaust gas that has been passed through the adsorption tower on the regeneration side of apparatus A is passed through the adsorption tower on the regeneration side of apparatus B as regeneration gas. The technique described in Patent Document 1 makes it possible to reduce the amount of regeneration gas used in the entire apparatus.

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

[0008] Patent No. 5074116 Patent No. 4058278

[0009] However, the technology described in Patent Document 1 above cannot reduce the amount of exhaust gas from the regeneration gas in a single device (for example, device A alone or device B alone) 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 pressure equal to or higher than that of the raw material gas, such as a compressor, is required, which increases the cost of the equipment and may limit the applicable processes.

[0011] The present invention has been made in consideration of the above problems, and aims 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 product gas.

[0012] The present inventors have conducted extensive research to solve the above problems. As a result, they have discovered that by applying a TSA system with a multi-tower switching configuration including three or more adsorption towers and providing piping connecting the respective adsorption towers, it is possible to efficiently utilize the regeneration gas without the need for a compressor or the like. That is, by adopting a method in which, when at least two of the three adsorption towers are performing a regeneration process, the regeneration gas is sequentially circulated through each of the adsorption towers performing 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 thus 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 material gas, repeatedly performing an adsorption step in which the impurities in the raw material gas are adsorbed and removed in the adsorption towers by a TSA (Thermal Swing Adsorption) system, and a regeneration step in which the impurities adsorbed in the adsorption towers are desorbed from the adsorption towers by heating 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 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, 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 through each of the adsorption towers performing the regeneration step. [2] The gas purification method according to [1] above, wherein 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 undergoing the cooling step, and the regeneration gas discharged from the adsorption tower undergoing the cooling step is introduced into the adsorption tower undergoing the heating step. [3] The gas purification method according to [1] or [2] above, 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 gas purification method according to [1] above, wherein the components contained in the impurities adsorbed and removed by the adsorbent are at least H ２ O, CO ２ , O ２[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; a regeneration 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 regeneration gas inlet pipe connected to the other end of each of the adsorption towers for introducing the regeneration gas into the adsorption tower. a gas purification apparatus comprising: on-off valves provided at one end or the other end of the adsorption towers in the adsorption introduction pipe, the regeneration gas discharge pipe, the product gas discharge pipe, and the regeneration gas introduction pipe, respectively; and a heating unit provided in the adsorption tower for heating the adsorbent or the regeneration gas, wherein an adsorption tower connecting pipe is provided between each of the three adsorption towers, connecting the one end of the adsorption tower to which the regeneration gas discharge pipe is connected and the other end to which the regeneration gas introduction pipe is connected, and a switching valve is provided in the adsorption tower connecting pipe. [6] The gas purification apparatus described in [5], wherein the adsorption tower connecting pipe is provided so that all three adsorption towers are connected in a circular configuration. [7] The gas purification apparatus described in [5] or [6], 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 towers. [8] The gas purification apparatus according to the above [5] or [6], characterized in that a heat exchanger for cooling the regeneration gas flowing through the adsorption tower connecting pipe is provided on the upstream 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 flowing through the regeneration gas discharge pipe is provided between the adsorption tower and an open / close valve provided in the regeneration gas discharge pipe.

[10] The gas purification apparatus according to the above [9], characterized in that a drain trap is 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 , CO, and hydrocarbons.

[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 undergoing a regeneration process, the regeneration gas is sequentially circulated through each of the adsorption towers undergoing the regeneration process. By employing this method, the flow rate of the regeneration gas required for heating and cooling the adsorption towers can be reduced, and the flow rate of the regeneration gas exhaust gas discharged from the adsorption towers during the regeneration process can also be reduced. This reduces the amount of the regeneration gas exhaust gas contained in the purified gas, enabling an increased recovery rate as product gas.

[0015] Furthermore, the gas purification apparatus according to the present invention employs a configuration in which an adsorption tower connecting pipe is provided between each of the three adsorption towers, connecting one end of the adsorption tower to which the regeneration gas discharge pipe is connected and the other end to which the regeneration gas introduction pipe is connected, and a switching valve is provided on the adsorption tower connecting pipe. According to the present invention, by employing this configuration, as described above, it is possible to reduce the flow rate of the regeneration gas required for heating and cooling the adsorption towers, and also to reduce the flow rate of the regeneration gas exhaust gas discharged from the adsorption towers. Furthermore, the regeneration gas can be efficiently utilized without the need for a compressor or the like. This reduces the amount of regeneration gas exhaust gas contained in the purified gas, thereby realizing a gas purification apparatus capable of increasing the recovery rate of the product gas.

[0016] FIG. 1 is a diagram schematically illustrating 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. FIG. 2 is a diagram schematically illustrating a gas purification method and a gas purification apparatus according to a first embodiment of the present invention, and is a system diagram showing an example of the flows of a raw material gas, a purified gas, and a regeneration gas based on a valve time chart in the gas purification apparatus shown in FIG. 1. FIG. 3 is a diagram schematically illustrating a gas purification method and a gas purification apparatus according to a first embodiment of the present invention, and is a system diagram showing another example of the flows of a raw material gas, a purified gas, and a regeneration gas in the gas purification apparatus shown in FIG. 1. FIG. 4 is a diagram schematically illustrating a gas purification method and a gas purification apparatus according to a 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 a raw material gas, a purified gas, and a regeneration gas shown in FIGS. 2 and 3. FIG. 5 is a diagram schematically illustrating 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. FIG. 6 is a diagram schematically illustrating 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. Fig. 7 is a diagram for schematically explaining the gas purification method and gas purification apparatus according to 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, purified gas, and regenerated gas shown in Fig. 5 and Fig. 6. Fig. 8 is a diagram for schematically explaining the gas purification method and 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.

[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 Figures 1 to 8 as appropriate. Note that the drawings used in the following description may show characteristic portions enlarged or simplified for the sake of clarity. Furthermore, the materials and the like exemplified in the following description are merely examples, and the present invention is not limited to them. Appropriate modifications can be made 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 Apparatus] First, a gas purification apparatus that can be used in operation by the gas purification method of this embodiment will be described in detail below. FIG. 1 is a system diagram showing the overall schematic configuration of a gas purification apparatus 1 of the first embodiment. FIGS. 2 and 3 are system diagrams showing the flows of raw material gas, purified gas, and regeneration gas based on valve time charts in the gas purification apparatus 1 shown in FIG. 1. FIG. 4 is a valve time chart showing the opening and closing operations of each valve for controlling the flows of raw material gas, purified gas, and regeneration gas shown in FIGS. 2 and 3 during the operation of the gas purification apparatus 1 shown in FIG. 1. In FIG. 4, time periods marked with diagonal lines indicate when the valves are open, and time periods marked with dots in the row of the heating unit indicate when the heating unit is operating and heating the adsorption tower.

[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 a TSA method to obtain a purified gas G2. Specifically, as shown in Fig. 1, the gas purification apparatus 1 of this embodiment is generally configured to include adsorption towers 2A, 2B, and 2C, a raw material gas introduction path (raw material gas introduction pipe) L1, a product gas discharge path (product gas discharge pipe) L2, a regeneration gas introduction path (regeneration gas introduction pipe) L3, and a regeneration gas discharge path (regeneration gas discharge pipe) L4.

[0021] More specifically, the gas purification system 1 includes three adsorption towers 2A, 2B, and 2C, each 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 system 1 also includes a raw material gas inlet path L1 connected to one end 2a of each of the adsorption towers 2A, 2B, and 2C, through which the raw material gas G1 is introduced into the adsorption towers 2A, 2B, and 2C, and a regeneration gas outlet path L4 through which the regeneration gas G3 is discharged from the adsorption towers 2A, 2B, and 2C. The gas purification system 1 also includes a product gas outlet path L2 connected to the other end 2b of each of the adsorption towers 2A, 2B, and 2C, through which the purified gas G2 is discharged from the adsorption towers 2A, 2B, and 2C, and a regeneration gas inlet path L3 through which the regeneration gas is introduced into the adsorption towers 2A, 2B, and 2C. The gas purification apparatus 1 is also equipped with on-off 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 material gas inlet path L1, the product gas outlet path L2, the regeneration gas inlet path L3, and the regeneration gas outlet path L4.

[0022] In the gas purification system 1 of this embodiment, an adsorption tower connecting path (adsorption tower connecting pipe) L5 ​​is provided between each of the three adsorption towers 2A, 2B, and 2C, connecting one end 2a of each of the adsorption towers 2A, 2B, and 2C, to which the regeneration gas discharge path L4 is connected, to 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 vicinity of the adsorption towers 2A, 2B, and 2C, respectively.

[0023] The illustrated gas purification apparatus 1 is also provided with connecting pipes L6a, L6b, and L6c that connect the confluence of the raw material gas inlet path L1 and the regeneration gas outlet path L4 to one end 2a of each of the three adsorption towers 2A, 2B, and 2C, and connecting pipes L7a, L7b, and L7c that connect the confluence of the product gas outlet path L2 and the regeneration gas inlet path L3 to the other end 2b of each of the three adsorption towers 2A, 2B, and 2C. Furthermore, the illustrated gas purification apparatus 1 is also provided with a regeneration gas flow rate adjustment valve NV1 that is provided in the regeneration gas inlet path L3 near the branch point from the product gas outlet 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 material gas introduction path L1 is a path for introducing the raw material gas G1 to be purified into the adsorption towers 2A, 2B, and 2C of the gas purification apparatus 1. One end of the raw material gas introduction path L1 in the illustrated example is connected to a raw material gas storage means (not shown), and the other end branches into three, which are connected to connecting pipes L6a, L6b, and L6c connected to one end 2a of each of the three adsorption towers 2A, 2B, and 2C. The connection point between the raw material gas introduction path L1 and the connecting pipes L6a, L6b, and L6c is the confluence point of the raw material 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 the product gas (purified gas G2). In the illustrated example, one end of the product gas discharge path L2 branches into three, which are connected to connecting 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). The product gas discharge path L2 also has a branch point toward the other end to which the regeneration gas introduction path L3 branches.

[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 purified gas G2, which becomes the product gas, can be started and stopped.

[0029] The regeneration gas introduction line L3 is a line for extracting a portion of the purified gas G2 from the product gas discharge line L2 as a regeneration gas G3. One end of the regeneration gas introduction line L3 is connected to the product gas discharge line L2 and branches off from the product gas discharge line 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 branches into three, which are 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. Also, at the other end of the regeneration gas introduction path L3, just before it branches into the three connecting pipes L7a, L7b, and L7c, open / close 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 a regeneration gas flow rate control valve NV1 in a 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 step for regenerating the adsorbent 6 filled in the adsorption columns 2A, 2B, and 2C, and supplies the regeneration gas G3 at a predetermined flow rate to the adsorption columns 2A, 2B, and 2C. The regeneration gas flow rate control valve NV1 is not particularly limited, and may be, for example, a general flow meter, a mass flow controller (MFC), or other flow control device.

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

[0033] Furthermore, on one end side of the regeneration gas discharge path L4, just before it branches into three connecting pipes L6a, L6b, and L6c, open / close valves V4a, V4b, and V4c are provided, respectively, so that the flow of the regeneration gas G3 discharged as exhaust gas from the adsorption towers 2A, 2B, and 2C can be started and stopped.

[0034] Each of the three adsorption towers 2A, 2B, and 2C has an adsorption tower connecting path L5 that connects one end 2a, to which the regeneration gas outlet path L4 is connected, to the other end 2b, to which the regeneration gas introduction path L3 is connected. The adsorption tower connecting path L5 also has switching valves V5a, V5b, V5c, V5d, V5e, and V5f in the vicinity of 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, which are connected to connecting pipes L6a, L6b, and L6c connected to one ends 2a of the three adsorption towers 2A, 2B, and 2C, respectively. Similarly to the one end, the other end of the adsorption tower connecting path L5 also branches into three, which are connected to connecting pipes L7a, L7b, and L7c connected to the other ends 2b of the three adsorption towers 2A, 2B, and 2C, respectively.

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

[0037] The adsorption towers 2A, 2B, and 2C are separation devices for obtaining purified gas G2 by adsorbing and removing impurities contained in the 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 heat-resistant, pressure-resistant, and corrosion-resistant material for the casing 5. The material for such a casing 5 can be appropriately selected taking into consideration, for example, the internal temperature conditions, pressure conditions, the adsorbent, the raw material gas G1 used, the impurities contained in the raw material gas G1, etc., but a material that can repeatedly perform gas purification under these conditions is preferable. For example, as described in detail below, in a case where 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, it is preferable to use a metal such as stainless steel as the material for the casing 5.

[0039] The housing 5 may take any form 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 form of such a housing 5 is a cylindrical one having openings on both ends 2 a and 2 b.

[0040] The adsorbent 6 is used to remove impurities from the source gas G1. The adsorbent 6 is filled in the space inside the housing 5. As the adsorbent 6, one or more types of adsorbents that can selectively adsorb 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 source gas G1 to be purified and the gas components that become impurities. The shape and dimensions of the adsorbent 6 inside the casing 5 may also be appropriately determined. Furthermore, in addition to the adsorbent 6, a catalyst (not shown) for accelerating the adsorption process and the regeneration process may be disposed inside the casing 5. Examples of such catalysts include palladium, copper, and ruthenium.

[0042] The heating unit 9 heats the adsorbent 6 and the regeneration gas G3 by heating the housing 5 from the outside when regenerating the adsorbent 6. 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. Furthermore, in the heating unit 9 provided spirally around the housing 5 as in the example shown in FIG. 1 , a gap is provided so that adjacent heating units 9 do not come into contact with each other in the axial direction of the housing 5, but the heating units 9 may also be in contact with each other, for example.

[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, an insulated nichrome heating wire, etc. 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 it may be any unit capable of heating the adsorbent 6 or the regeneration gas G3 to any desired temperature.

[0045] Although not shown in Fig. 1 and other figures, the adsorption towers 2A, 2B, and 2C may be provided with cooling means for cooling the adsorbent 6 disposed inside the housing 5. Examples of such cooling means include cooling pipes configured to circulate a refrigerant inside the pipes.

[0046] In this embodiment, a heat transfer material (not shown) can be disposed 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 configured to be 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 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 improve 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 be any material having a thermal conductivity of 1 or more, and examples thereof 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 Heat Co., Ltd.

[0048] The heat insulating material (not shown) is intended to prevent 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 leaking from the adsorption towers 2A, 2B, and 2C to the outside in the heating step (regeneration step) for regenerating the adsorbent 6 provided in the adsorption towers 2A, 2B, and 2C, and it is also possible to prevent heat from flowing from the outside into the adsorption towers 2A, 2B, and 2C in the cooling step (regeneration step). This makes it possible to improve the heat conduction efficiency in the regeneration step 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. Furthermore, a space for installing cooling pipes (not shown) and the 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 pipes, and the heating unit 9, which can prevent heat from leaking out of the adsorption towers 2A, 2B, and 2C to the outside in the heating step (regeneration step) for regenerating the adsorbent 6 in the adsorption towers 2A, 2B, and 2C, and can prevent heat from flowing in from the outside to the adsorption towers 2A, 2B, and 2C in the cooling step (regeneration step).

[0050] The heat insulating material may have a thermal conductivity of less than 1, and preferably has a lower thermal conductivity value. Examples of heat insulating materials include glass wool and rock wool, but are not particularly limited thereto.

[0051] In the adsorption towers 2A, 2B, and 2C provided in the gas purification apparatus 1 of this embodiment, components contained in the impurities to be adsorbed and removed by the adsorbent 6 include, for example, H ２ O, CO ２ , O ２ , CO, and hydrocarbons can be exemplified.

[0052] According to the gas purification apparatus 1 of this embodiment, by providing the adsorption tower connecting path L5 configured as described above, for example, when at least two of the three adsorption towers 2A, 2B, and 2C are performing a regeneration process for 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 the need for a compressor or the like. Furthermore, 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 exhaust gas of the regeneration gas G3 contained in the purified gas G2, which is the product gas, is reduced, making it possible to increase the recovery rate of the product gas.

[0053] The gas type, flow rate, pressure, and temperature of the raw material 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 applications to purify expensive rare gases, and for gas generators such as hydrogen generators that have a limited gas generation amount (raw material gas amount) and require a large amount of product gas (usable gas amount).

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

[0055] Furthermore, in this embodiment, if a gas heater is used as the heating unit, the number of heating units required can be reduced by providing this heating unit in the adsorption tower connecting path L5 connected to the adsorption towers 2A, 2B, and 2C. When a heating unit is provided in the adsorption tower connecting path L5, the switching valves V5d, V5e, and V5f connected to the other ends 2b of the adsorption towers 2A, 2B, and 2C must be heat-resistant valves that can be used at the heating temperatures of the heating units. Even if a heating unit is not provided in the adsorption tower connecting path L5, the regenerated gas G3 discharged from the adsorption towers 2A, 2B, and 2C is at a high temperature. Therefore, as described above, the switching valves V5a, V5b, and V5c and the on-off valves V4a, V4b, and V4c through which the high-temperature regenerated gas G3 flows must be heat-resistant valves that can be used at the heating temperatures of the adsorption towers 2A, 2B, and 2C.

[0056] 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] Furthermore, 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 Figure 1) that allows the adsorption towers to be connected in series.

[0058] Next, an example of the operation of the gas purification apparatus 1 will be described with reference to Figures 2 to 4. When the gas purification apparatus 1 is operated based on the valve time chart shown in Figure 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 regeneration gas G3 shown in Figure 2. At this time, as shown in Figure 2, the 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, thereby discharging the purified gas G2 as a product via the product gas discharge path L2.

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

[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 open, and the other valves are closed. That is, in the operation process shown in Fig. 2, a portion 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 the one end 2a of the adsorption tower 2B is introduced from the other end 2b into the adsorption tower 3C via the adsorption tower connecting path L5. The exhaust gas of the regeneration gas G3 discharged from the one end 2a of the adsorption tower 3C is then discharged to the outside of the adsorption tower 3C via 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 that is performing the heating step (regeneration step) is turned on.

[0062] Next, from 11 hours after the start of operation until 12 hours later, the operation process is carried out with the flows of raw material gas G1, purified gas G2, and regeneration gas G3 shown in Fig. 3. During this process, as shown in Fig. 3, raw material gas G1 continues to be supplied only to adsorption tower 2A from raw material gas introduction path L1, and adsorption tower 2A performs an adsorption step on raw material gas G1, thereby discharging purified gas G2 as a product via product gas discharge path L2.

[0063] Meanwhile, the regeneration process continues in the adsorption towers 2B and 2C. However, in the operation process shown in FIG. 3, unlike the operation process shown in FIG. 2, a pressurization process is carried out in the adsorption tower 2B, and a standby 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 addition, 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, the above-described operating process can be performed in rotation for the three adsorption towers 2A, 2B, and 2C, for example, based on the valve time chart shown in FIG. 4.

[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 adsorbs and removes impurities from the raw material gas G1 by the TSA method to obtain a purified gas G2 as a product. That is, the gas purification method of this embodiment repeatedly performs an adsorption step (1) in which the adsorption towers 2A, 2B, and 2C adsorb and remove impurities from the raw material gas G1, and a regeneration step (2) in which the adsorption towers 2A, 2B, and 2C are heated to desorb the impurities adsorbed in the adsorption towers 2A, 2B, and 2C from the adsorption towers 2A, 2B, and 2C. In addition, in this embodiment, of the three adsorption towers 2A, 2B, and 2C, at least one adsorption tower 2A performs the adsorption step (1), and gas purification is performed by using a portion of the purified gas G2 obtained by removing impurities from the raw gas G1 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 this embodiment is a method in which, when at least two of the three adsorption towers 2A, 2B, and 2C are performing 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). That is, in this embodiment, an example will be described in which the adsorption step (1) is performed in one adsorption tower 2A, and simultaneously the regeneration step (2) is performed in two adsorption towers 2B and 2C.

[0069] (Adsorption Step (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 operating 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 connecting pipe L6a.

[0070] The adsorbent 6 provided in the adsorption tower 2A adsorbs and removes impurities from the raw material gas G1 to generate a purified gas (product gas) G2, which is then discharged to the outside as a product gas via the connecting 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 to be removed in the gas purification method of the present embodiment, are not particularly limited, but for example, at least H ２ O, CO ２ , O ２ , CO, and hydrocarbons.

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

[0073] (Regeneration Step (2)) In the regeneration step (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 step (2) is carried out in the adsorption towers 2B and 2C simultaneously with the adsorption step (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) of heating the adsorption tower 2C and a cooling step (2-2) of 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 adsorption tower 2C among the three adsorption towers 2A, 2B, and 2C performs the heating step (2-1) and one adsorption tower 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 activated 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 regeneration gas G3 extracted from the regeneration gas introduction path L3 is introduced into the adsorption tower 2B, thereby cooling the adsorbent 6 in the housing 5.

[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 are 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 operation 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 introduction path L1, and this adsorption tower 2A performs the adsorption step (1) on the raw material gas G1, so that the purified gas G2, which is a product, continues to be discharged via the product gas discharge path L2.

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

[0081] In the gas purification method of this 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 are performing 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 exhaust gas of the regeneration gas G3 contained in the purified gas G2 and makes 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 gas purification apparatus according to a second embodiment of the present invention will be described below. In the following description, the same reference numerals will be used to designate components that are the same as (or similar to) the gas purification apparatus 1 of the first embodiment, and detailed descriptions thereof may be omitted. In the following description, detailed descriptions of procedures and conditions that are the same as those of the gas purification method of the first embodiment will also be omitted.

[0085] Fig. 5 is a system diagram showing the overall schematic configuration of a gas purification apparatus 1A of a second embodiment. Fig. 7 is a valve time chart showing the opening and closing operations of each valve for controlling the flows of the raw material gas G1, purified gas G2, and regenerated gas G3 in the gas purification apparatus 1A shown in Fig. 5. In Fig. 7, time periods marked with diagonal lines in the rows of valves indicate that the valves are open, and time periods marked with dots in the rows of heating units indicate that the heating units are operating and heating the adsorption towers.

[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 introduction path L1, a product gas discharge path L2, a regeneration gas introduction path L3, and a regeneration gas discharge 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 includes adsorption tower connection paths (adsorption tower connection pipes) L5A1, L5A2, and L5A3 that connect one end 2a of one of the adsorption towers 2A, 2B, and 2C to the other end 2b of another adsorption tower via connection pipes L6a, L6b, and L6c or connection pipes L7a, L7b, and L7c.

[0087] 5, one end 2a of the adsorption tower 2C is connected to the other end 2b of the adsorption tower 2A via connection pipes L6c and L7a via an adsorption tower connecting path L5A1. Also, one end 2a of the adsorption tower 2A is connected to the other end 2b of the adsorption tower 2B via connection pipes L6a and L7b via an adsorption tower connecting path L5A2. Also, one end 2a of the adsorption tower 2B is connected to the other end 2b of the adsorption tower 2c via an adsorption tower connecting path L5A3 via connection pipes L6b and L7c.

[0088] When operating a gas purification apparatus 1A having adsorption tower connecting paths L5A1, L5A2, and L5A3 as shown in Fig. 5, each operating process can be performed based on, for example, the valve timing chart shown in Fig. 7. That is, in the gas purification apparatus 1A of the second embodiment, as in 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 predetermined timings. As a result, in the gas purification apparatus 1A as well, when at least two of the three adsorption towers 2A, 2B, and 2C are performing the regeneration step (2), it is possible to perform an operating 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 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 sides 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 configured as described above, 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 through 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. Furthermore, as described above, the flow rate of the regeneration gas G3 required for heating and cooling the adsorption towers 2A, 2B, and 2C can be reduced, thereby reducing the flow rate of the exhaust gas of the regeneration gas G3 discharged from the adsorption towers 2A, 2B, and 2C. 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 the recovery rate as the product gas can be increased.

[0091] Third Embodiment Next, a gas purification method and gas purification apparatus according to a third 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 apparatuses 1 and 1A of the first and second embodiments will be denoted by the same reference numerals, and detailed descriptions thereof may be omitted. In the following description, detailed descriptions of procedures and conditions similar to those of the gas purification methods of the first and second embodiments will also be omitted.

[0092] Fig. 6 is a system diagram showing the overall schematic configuration of a gas purification apparatus 1B of a third embodiment. Fig. 7 is a valve time chart showing the opening and closing operations of each valve for controlling the flows of the raw material gas G1, purified gas G2, and regenerated gas G3 in the gas purification apparatus 1B shown in Fig. 6. In Fig. 7, time periods marked with diagonal lines in the rows of valves indicate that the valves are open, and time periods marked with dots in the rows of heating units indicate that the heating units are operating and heating the adsorption towers.

[0093] A gas purification apparatus 1B of the third embodiment shown in Figure 6 is similar to the gas purification apparatus 1A of the second embodiment shown in Figure 5 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, and further includes adsorption tower connecting paths L5A1, L5A2, and L5A3 that connect one end 2a of one of the adsorption towers 2A, 2B, and 2C to the other end 2b of another adsorption tower. The gas purification apparatus 1B of the third embodiment shown in Figure 6 is also similar to the gas purification apparatus 1A of the second embodiment shown in Figure 5 in that it can perform each operating process based on, for example, the valve timing chart shown in Figure 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 regeneration 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, respectively, provided in the adsorption tower connecting paths L5A1, L5A2, and L5A3.

[0094] As the heat exchangers 7a, 7b, and 7c shown in FIG. 3, for example, fin tube, turbilent tube, or plate fin type heat exchangers can be used, but the type of heat exchanger, the cooling method (air cooling or water cooling), and the like 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 and immediately after the start of the cooling step (2-2), the temperature of the high-temperature regeneration gas G3 discharged from the outlet sides of the adsorption towers 2A, 2B, and 2C is preferably reduced to 150° C. or less by the heat exchangers 7a, 7b, and 7c, and more preferably reduced to 80° C. or less. This is because, if the outlet temperatures of the heat exchangers 7a, 7b, and 7c exceed 150° C., it is necessary to use expensive all-metal diaphragm valves (for example, the FWB-71 series manufactured by Fujikin Co., Ltd.) for the switching valves V5a, V5b, and V5c arranged on the outlet sides of the heat exchangers 7a, 7b, and 7c.

[0096] On the other hand, by cooling the regeneration 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 (for example, FPR-ND-71-6.35-PI manufactured by Fujikin Co., Ltd.) using polyimide or PFA as the seat material.

[0097] Furthermore, when the regeneration 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 (for example, FPR-ND-71-6.35 manufactured by Fujikin Co., Ltd.) can be used.

[0098] It is desirable to avoid using the all-metal diaphragm described above, not only because it is expensive, but also because its structural characteristics mean that even a small amount of dust can easily cause an internal leak, allowing gas to flow even when the valve is closed, which can lead to malfunctions in the gas purification device.

[0099] <Fourth Embodiment> Next, a gas purification method and gas purification apparatus according to a fourth embodiment of the present invention will be described below. Note that in the following description, the same reference numerals will be used to designate components that are the same as (or similar to) the gas purification apparatuses 1, 1A, and 1B of the first to third embodiments described above, and detailed descriptions thereof may be omitted. Furthermore, in the following description, detailed descriptions of procedures and conditions that are the same as those of the gas purification methods of the first to third embodiments will be omitted.

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

[0101] A gas purification apparatus 1C of a fourth embodiment shown in Figure 8 is similar to the gas purification apparatus 1A of the second embodiment shown in Figure 5 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, and further includes adsorption tower connecting paths L5A1, L5A2, and L5A3 that connect one end 2a of one of the adsorption towers 2A, 2B, and 2C to the other end 2b of another adsorption tower. The gas purification apparatus 1C of the fourth embodiment shown in Figure 8 is also similar to the gas purification apparatus 1A of the second embodiment shown in Figure 5 in that it can perform each operating process based on, for example, the valve timing chart shown in Figure 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 flowing through the regeneration gas discharge path L4 are provided between the adsorption columns 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 on the outlet sides of these heat exchangers 71a, 71b, and 71c in the regeneration gas discharge path L4. Figure 8 shows an example in which drain traps 8a, 8b, and 8c are provided at the ends of three drain pipes L41, which are inlet pipes from the regeneration gas discharge path L4.

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

[0104] Furthermore, the gas purification apparatus 1C of this embodiment, which is provided with the drain traps 8a, 8b, and 8c configured as described above, has the following effect. Specifically, the regeneration gas G3 discharged from the adsorption tower after the heating step (2-1) contains moisture desorbed from the adsorbent 6, and is cooled by the heat exchangers 71a, 71b, and 71c, generating a large amount of drain. If a large amount of such drain is generated, the regeneration gas discharge path L4 may be clogged with the drain. However, 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 regeneration gas discharge path L4 from being clogged as described above.

[0105] <Effects> As described above, the gas purification method using the gas purification apparatuses 1, 1A, 1B, and 1C of this embodiment employs a method in which, when at least two of the three adsorption towers 2A, 2B, and 2C are performing 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 employing 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. This reduces the amount of 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.

[0106] Furthermore, the gas purification apparatus according to the present invention includes an adsorption tower connection path L5 between each of the three adsorption towers 2A, 2B, and 2C, connecting one end 2a of each of the adsorption towers 2A, 2B, and 2C, to which the regeneration gas outlet path L4 is connected, and the other end 2b of each of the adsorption towers 2A, 2B, and 2C, to which the regeneration gas introduction path L3 is connected. The adsorption tower connection path L5 is also provided with switching valves V5a, V5b, and V5c. By adopting this configuration, as described above, 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 can also be reduced. Furthermore, the regeneration gas G3 can be efficiently utilized without the need for a compressor (booster), etc. This reduces the amount of exhaust gas of the regeneration gas G3 contained in the purified gas G2, thereby realizing the gas purification apparatuses 1, 1A, 1B, and 1C, which can increase the recovery rate of the product gas.

[0107] Furthermore, the regeneration gas G3, which is heated by absorbing heat from the adsorbent 6 and ventilated through 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] Although an example of a gas purification method and a gas purification apparatus according to the present invention has been described above using an embodiment, the present invention is not limited to the above embodiment. The configurations and combinations thereof in the above embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope of the present invention.

[0109] For example, in each of the above-described 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.

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

[0111] <Purification conditions, regeneration conditions, and configuration of gas purification apparatus> In this example, 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, employing a three-tower switching TSA method as shown in Figure 1 and having an adsorption tower connecting path L5 (Example). In this example, as a comparative example to the three-tower switching gas purification apparatus 1 shown in Figure 1, a gas purification apparatus having a conventional configuration that does not have an adsorption tower connecting path and is a two-tower switching type as disclosed in Japanese Patent Laid-Open No. 2020-65984 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 material gas composition: H ２ +H ２ O (2) H ２ O concentration: 2800 ppm (component to be removed) (3) Flow rate: 100 Nm ３ / h (4) Pressure: 800 kPaG (5) Temperature: 25°C (6) Adsorbent: Zeolite (synthetic) (7) Regeneration temperature: 300°C (8) Regeneration pressure: atmospheric pressure

[0114] In both the Examples and Comparative Examples, the adsorption tower had an inner cylinder (casing) made of SUS304 (size: Sch10S, 80A) and a height of 1,330 mm. As described above, synthetic zeolite was used as the adsorbent, and its packing height (height of the adsorbent layer) was 1,240 mm.

[0115] [Operating Procedure] (Example) In this example, a three-tower switching type gas purification apparatus of the example was used to adsorb impurities such as moisture from a raw material gas and obtain hydrogen as a purified gas in the following manner. First, based on the valve time chart shown in Figure 4 and the operating process shown in Figure 2, raw material gas G1 was supplied from raw material gas introduction path L1 to adsorption tower 2A to perform the adsorption step, and purified gas G2 was discharged via product gas discharge path L2.

[0116] Simultaneously with the adsorption step in the adsorption tower 2A, a regeneration step was performed in the adsorption towers 2B and 2C. The adsorption tower 2B performed a cooling step (regeneration step) to cool the adsorbent 6, and the adsorption tower 2C performed a heating step (regeneration step) to heat the adsorbent 6 and a cooling step (regeneration step). Specifically, a portion of the regeneration gas G3 was introduced from the other end 2b of the adsorption tower 2B via the regeneration gas introduction path L3, and the exhaust gas of the regeneration gas G3 discharged from the one end 2a of the adsorption tower 2B was introduced into the adsorption tower 3C from the other end 2b via the adsorption tower connecting path L5. The exhaust gas of the regeneration gas G3 discharged from the one end 2a of the adsorption tower 3C was discharged to the outside of the adsorption tower 3C via the regeneration gas discharge path L4. During this operation, only the heating unit 9 of the adsorption tower 2C, which was performing the heating step (regeneration step), was turned on.

[0117] Next, in the operation process shown in Fig. 3, the adsorption step was carried out in the adsorption tower 2A, the adsorption tower 2B was subjected to the pressurization step, and the adsorption tower 2C was subjected to the standby step. In this example, the above 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. 4.

[0118] (Comparative Example) Using a gas purification apparatus of the comparative example with a two-tower switching system, impurities such as moisture were adsorbed from a raw material gas and hydrogen was obtained as a purified gas in the following manner. First, the raw material gas was continuously sent to one adsorption tower to be used as a purified gas, and in the other adsorption tower, a portion of the purified gas obtained from one adsorption tower was used as a regeneration gas and circulated through 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 material gas was purified in one of the adsorption towers under the same conditions as above, and in the other adsorption tower, a portion of the purified gas obtained in one of the adsorption towers was circulated as regeneration gas into the other adsorption tower, thereby cooling 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> The following Table 1 shows the operating processes of the two-tower switching system (Comparative Example) and the three-tower switching system (Example), and the results of comparing the amounts 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 feed gas supplied per cycle) - (Amount of waste regeneration gas per cycle) / (Amount of feed gas supplied per cycle)}.

[0122]

[0123] As shown in Table 1, in the comparative example using a two-tower switching gas purification apparatus with 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 the example using the configuration according to the present invention, i.e., the three-tower switching TSA method and the gas purification apparatus 1 having the 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 improvement over 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 regeneration gas discharged from the adsorption tower in the regeneration process can also be reduced, thereby reducing the amount of exhaust regeneration gas contained in the purified gas and increasing the recovery rate of the purified gas that becomes the product.

[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 particularly suitable for applications to gas generators, such as purification of expensive rare gases, and hydrogen generators that have a limited amount of gas generation (amount of raw gas) and require a large amount of product gas (amount of usable gas).

[0126] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C... Gas purification device 2A, 2B, 2C... Adsorption tower 2a... One end 2b... Other end 5... Housing 6... Adsorbent 9... Heating unit L1... Raw material gas introduction path (raw material gas introduction piping) L2... Product gas discharge path (product gas discharge piping) L3... Regenerated gas introduction path (regenerated gas introduction piping) L4... Regenerated gas discharge path (regenerated gas discharge piping) L5, L5A1, L5A2, L5A3... Adsorption tower connecting path (adsorption tower connecting piping) L41... Drain pipe L6a, L6b, L6c, L7a, L7b, L7c... Connecting piping V1a, V1b, V1c, V2a, V2b, V2c, V3a, V3b, V3c, V4a, V4b, V4c... Opening and closing valve V5a, V5b, V5c, V5d, V5e, V5f...switching valves 7a, 7b, 7c, 71a, 71b, 71c...heat exchangers 8a, 8b, 8c...drain traps NV1...regenerated gas flow rate adjustment valve G1...raw material gas G2...purified 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 gas, repeatedly carrying out an adsorption process in which the impurities in the raw gas are adsorbed and removed in the adsorption towers by a TSA (Thermal Swing Adsorption) method, and a regeneration process in which the impurities adsorbed in the adsorption towers are released from the adsorption towers by heating the adsorption towers, and at least one of the three adsorption towers performs the adsorption process, 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 process is used as a regeneration gas for purging the adsorption towers in the regeneration process, characterized in that when at least two of the three adsorption towers perform the regeneration process, the regeneration gas is sequentially circulated to each of the adsorption towers performing the regeneration process.

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

3. A gas purification method as described in claim 1 or claim 2, characterized in that the temperature of the regeneration gas discharged from the adsorption tower undergoing the cooling process is cooled to 150°C or less before being introduced into the adsorption tower undergoing the heating process.

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 regenerated gas outlet pipe for discharging the regenerated gas introduced into the adsorption tower from the adsorption tower, each connected to one end of the adsorption tower; a product gas outlet pipe for discharging the purified gas from the adsorption tower, and a regenerated gas inlet pipe for introducing the regenerated gas into the adsorption tower, each connected to the other end of the adsorption tower; open / close valves provided on one end or the other end of the adsorption tower in the raw material gas inlet pipe, the regenerated gas outlet pipe, the product gas outlet pipe, and the regenerated gas inlet pipe, respectively; and a heating unit provided in the adsorption tower for heating the adsorbent or the regenerated 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. 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 a circular shape.

7. A gas purification system according to claim 5 or 6, characterized in that 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. A gas purification apparatus as described in claim 5 or 6, characterized in that a heat exchanger for cooling the regenerated gas flowing through the adsorption tower connecting piping is provided on the primary side of the switching valve provided in the adsorption tower connecting piping.

9. A gas purification apparatus as described in claim 5 or 6, characterized in that a heat exchanger for cooling the gas flowing through the regeneration gas exhaust piping is provided between the adsorption tower and an opening / closing valve provided in the regeneration gas exhaust piping.

10. A gas purification apparatus as described in claim 9, characterized in that a drain trap is provided inside the heat exchanger provided in the regeneration gas discharge piping or in the regeneration gas discharge piping 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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