Pressure fluctuation adsorption type gas separation method and pressure fluctuation adsorption type gas separation device

Abstract

To provide a technique capable of recovering an easily adsorbable component or a hardly adsorbable component at high concentration and high recovery rate, and improving both purity and recovery rate of high value added gas.SOLUTION: A pressure fluctuation adsorption gas separation method recovers an easily adsorbable component and a hardly adsorbable component from a raw gas by using a separation device 200 including lower cylinders 10B, 11B and upper cylinders 10U, 11U filled with the first adsorbent, a raw gas storage tank 1 that stores the raw gas, and an easily adsorbable component storage tank 2 that stores the easily adsorbable component, and purification cylinders 12A, 12B filled with a second adsorbent using the gas containing the easily adsorbable component that is easily adsorbed by a first adsorbent, and the hardly adsorbable component that is hardly adsorbed by the first adsorbent as the raw gas. The method includes a separation step of introducing the hardly adsorbable component derived from the separation device 200 into the purification cylinders 12A, 12B to perform separation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure swing adsorption gas separation method and a pressure swing adsorption gas separation apparatus. [Background technology]

[0002] Generally, in the manufacturing process of semiconductor products such as semiconductor integrated circuits, liquid crystal panels, solar cell panels, magnetic disks, etc., various processes are carried out using plasma generated by high-frequency discharge in a rare gas atmosphere. In recent years, krypton and xenon have attracted attention for more advanced processing, and demand is expected to continue to increase.

[0003] However, krypton and xenon are produced as by-products in large cryogenic air separation units, but their abundance in the atmosphere is low and there are only a few production plants, so supply is limited. Furthermore, due to their nature as by-products, it is difficult to increase production. For these reasons, krypton and xenon have been in short supply in recent years, and their prices, which are already extremely expensive, are rising even further.

[0004] Pressure Swing Adsorption (PSA) is a known method for recovering a target component from a mixed gas. Patent Document 1 shows that PSA can recover xenon from a mixed gas of xenon and nitrogen at a concentration of 99.9% and a recovery rate of 99.99%. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-61831 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, krypton and xenon are becoming increasingly expensive, and releasing them to the outside after using them as atmospheric gases would result in a significant increase in costs. Therefore, in order to make the process of using such expensive gases economically viable, it is extremely important to recover the used rare gases at a recovery rate of 99% or more and recycle them. Incidentally, exhaust gases from manufacturing facilities for semiconductor products, display devices, etc. consist mainly of atmospheric gases and purge gases introduced when the manufacturing facilities are evacuated.

[0007] On the other hand, in order to widely and economically utilize high-value-added gases, they must be highly purified to commercially available quality (for example, 99.99% or higher), and a high recovery rate is also required. However, in the method proposed in Patent Document 1, the purity and recovery rate of the high value-added gas have an inverse relationship, so if the purity of the high value-added gas is further improved, the recovery rate decreases, and if the recovery rate is improved, the purity of the high value-added gas decreases.

[0008] Thus, while there is a demand for further improvement in the recovery rate of high value-added gases, conventional technologies have not been able to recover strongly adsorbable components or weakly adsorbable components at high concentrations and with high recovery rates, thereby achieving both improved purity and improved recovery rate of high value-added gases. An object of the present invention is to provide a technology for recovering strongly adsorbable components or weakly adsorbable components at a high concentration and with a high recovery rate, thereby improving the purity and recovery rate of high-value-added gases. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides the following means. [1] A gas containing a readily adsorbable component that is readily adsorbable to a first adsorbent and a poorly adsorbable component that is poorly adsorbable to the first adsorbent is used as a raw material gas, a separation device including a lower column and an upper column filled with the first adsorbent, a raw material gas storage tank for storing the raw material gas, and a strongly adsorbable component storage tank for storing the strongly adsorbable component; a purification column filled with a second adsorbent that is easily adsorbable to the easily adsorbable component and is poorly adsorbable to the poorly adsorbable component, A pressure swing adsorption gas separation method for recovering the strongly adsorbable component and the weakly adsorbable component from the raw material gas, comprising: A pressure swing adsorption gas separation method comprising a separation step of introducing the gas discharged from the separation device into the purification column for separation. [2] The separation step a step of adsorbing a strongly adsorbable component in the gas discharged from the separation device onto the second adsorbent; and desorbing the strongly adsorbable component adsorbed on the second adsorbent. The pressure swing adsorption gas separation method according to [1], [3] The pressure swing adsorption gas separation method according to [2], characterized in that the second adsorbent is heated to desorb the strongly adsorbable component adsorbed on the second adsorbent. [4] A pressure swing adsorption gas separation apparatus that separates a feed gas containing an easily adsorbed component that is easily adsorbed by a first adsorbent and a poorly adsorbed component that is poorly adsorbed by the first adsorbent, a separation apparatus including a lower column and an upper column filled with the first adsorbent, a raw material gas storage tank for storing the raw material gas, and a strongly adsorbable component storage tank for storing the strongly adsorbable component; a purification column packed with a second adsorbent that is easily adsorbable to the easily adsorbable component and is poorly adsorbable to the poorly adsorbable component; a pipeline for introducing the gas discharged from the separation device into the purification column; A pressure swing adsorption gas separation apparatus comprising: [5] The pressure swing adsorption gas separation apparatus according to [4], further comprising a pipeline for delivering the gas discharged from the purification column to the raw gas storage tank. [6] The pressure swing adsorption gas separation apparatus according to [4], further comprising a heating means for heating the second adsorbent. [Effects of the Invention]

[0010] According to the present invention, it is possible to recover strongly adsorbable components or weakly adsorbable components at high concentrations and with high recovery rates, thereby achieving improvements in the purity and recovery rate of high-value-added gases. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a pressure swing adsorption gas separation apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a pressure swing adsorption gas separation apparatus according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a diagram showing a pressure swing adsorption gas separation apparatus according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing a pressure swing adsorption gas separation apparatus according to a fourth embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing a pressure swing adsorption gas separation device used in a comparative example. [Figure 6] 1 is a graph showing the results of an example. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] <Pressure swing adsorption gas separation device> A pressure swing adsorption gas separation apparatus according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the pressure swing adsorption gas separation apparatus 100 of this embodiment is composed of a gas separation apparatus 200 in the front stage and a purification apparatus 300 in the rear stage.

[0013] The gas separation apparatus 200 has the same configuration as the apparatus described in Japanese Patent Laid-Open No. 2006-061831, and for details, please refer to that patent document as appropriate. Only the main parts will be described below.

[0014] The gas separation apparatus 200 is a pressure swing adsorption type gas separation apparatus and includes a raw gas storage tank 1, a strongly adsorbed component storage tank 2, a weakly adsorbed component storage tank 3, a compressor 4, a compressor 5, and four adsorption columns: lower columns 10B and 11B, and upper columns 10U and 11U.

[0015] The raw material gas storage tank 1 is a tank for storing raw material gas containing at least an easily adsorbed component that is easily adsorbed to a certain adsorbent and a poorly adsorbed component that is poorly adsorbed to the adsorbent. The strongly adsorbable component storage tank 2 is a tank for storing the strongly adsorbable component, and the weakly adsorbable component storage tank 3 is a tank for storing the weakly adsorbable component.

[0016] The compressor 4 is a device that compresses the gas in the source gas storage tank 1 or the strongly adsorbable component storage tank 2 . The compressor 5 is a device that compresses the gas in the strongly adsorbable component storage tank 2.

[0017] The lower columns 10B, 11B and the upper columns 10U, 11U are filled with an adsorbent. The adsorbent has high or low adsorption properties for the target component in the raw material gas, and has high or low adsorption properties for components other than the target component.

[0018] The purification unit 300 is a unit for further purifying the gas of the weakly adsorbed components produced in the previous stage, and in this embodiment, a PSA unit is used. Specifically, the refining device 300 has two adsorption columns, refining columns 12A and 12B.

[0019] The purification columns 12A and 12B are filled with an adsorbent. The adsorbent has high or low adsorption properties for the target component in the raw gas, and high or low adsorption properties for components other than the target component. The adsorbent filled in the purification columns 12A and 12B can be the same as the adsorbent filled in the lower columns 10B and 11B and the upper columns 10U and 11U.

[0020] Next, the pipelines connecting the above-mentioned devices will be described. The pipeline L1 is a pipeline (path) through which the raw material gas is introduced into the raw material gas storage tank 1. The pipeline L2 is a pipeline that delivers the gas from the raw material gas storage tank 1 to the compressor 4. A valve V1 is provided midway along the pipeline L2. The pipeline L3 is a pipeline that delivers the gas in the strongly adsorbable component storage tank 2 to the compressor 4. A valve V2 is provided midway along the pipeline L3. The pipes L2 and L3 join together after the valves V1 and V2, respectively.

[0021] The pipe L4 is a pipe that introduces gas from the compressor 4 into the lower cylinder 10B. A valve V3 is provided midway along the pipe L4. The pipe L5 is a pipe that introduces gas from the compressor 4 into the lower cylinder 11B. A valve V4 is provided midway along the pipe L5.

[0022] The pipe L21 is a pipe that introduces the gas from the lower cylinder 10B into the upper cylinder 10U. A valve V5 is provided midway along the pipe L21. The pipe L22 is a pipe that introduces the gas from the lower cylinder 11B into the upper cylinder 11U. A valve V6 is provided midway along the pipe L22.

[0023] The pipeline L6 is a pipeline for introducing the gas from the upper columns 10U and 11U into the reservoir 3 for the weakly adsorbed component. Specifically, the pipeline L6 is made up of pipelines L61, L62, and L63, and the gas from the upper column 10U passes through pipelines L61 and L63, and the gas from the upper column 11U passes through pipelines L62 and L63, before being introduced into the weakly adsorbed component storage tank 3. Pipes L61 and L62 are provided with valves V7 and V8, respectively, midway.

[0024] Pipe line L7 is a path for delivering the weakly adsorbed components from the weakly adsorbed component storage tank 3, that is, the gas delivered from the gas separation device 200, to the purification columns 12A and 12B. Specifically, the pipeline L7 consists of pipelines L71, L72, and L73, and the gas drawn out from the weakly adsorbed component storage tank 3 is introduced into the purification column 12A through pipelines L71 and L72, and into the purification column 12B through pipelines L71 and L73. The pipelines L72 and L73 are provided with valves V16 and V17, respectively.

[0025] The pipe L8 is a pipe that introduces the weakly adsorbed component from the weakly adsorbed component storage tank 3 into the upper columns 10U and 11U as a countercurrent purge gas. Specifically, the pipeline L8 is made up of pipelines L81, L82, and L83, and the gas discharged from the weakly adsorbed component storage tank 3 is introduced into the upper column 10U through pipelines L83 and L81, and into the upper column 11U through pipelines L83 and L82. Valves V14 and V15 are provided midway along pipelines L81 and L82, respectively.

[0026] Pipes L9, L23, and L11 are pipes for returning the gas from the lower column 10B to the raw material gas reservoir tank 1. Pipes L9, L23, and L12 are pipes for returning the gas from the lower column 10B to the strongly adsorbable component storage tank 2. Pipe line L9 is provided with V12 midway. The pipes L11 and L12 are provided with valves V10 and V11 midway, respectively.

[0027] Pipes L10, L23, and L11 are pipes for returning the gas from the lower column 11B to the raw material gas storage tank 1. Pipes L10, L23, and L12 are pipes for returning the gas from the lower column 11B to the strongly adsorbable component storage tank 2. Pipe line L10 is provided with V13 midway.

[0028] The pipe L13 is a pipe that supplies the strongly adsorbable component from the strongly adsorbable component storage tank 2 to the outside of the apparatus system. A compressor 5 is provided midway along the pipe L13. Pipe line L14 is a pressure equalization line that equalizes the pressure between upper columns 10U and 11U. Pipe line L14 is provided with a valve V9 midway.

[0029] Pipe L15 is a pipe for supplying the weakly adsorbed components from the purification columns 12A and 12B to the outside of the apparatus system. Specifically, the pipeline L15 consists of pipelines L151, L152, and L153, ​​and the gas discharged from the purification column 12A passes through pipelines L151 and L153, ​​and the gas discharged from the purification column 12B passes through pipelines L152 and L153 and is supplied outside the system. The pipelines L151 and L152 are provided with valves V22 and V23, respectively.

[0030] The pipe L16 is a pipe that introduces the gas discharged from the purification columns 12A and 12B into the purification columns 12A and 12B as a counterflow purge gas. Specifically, the pipeline L16 consists of pipelines L161, L162, and L163, and the gas discharged from the purification columns 12A and 12B branches off midway through pipeline L153 and is introduced into the purification column 12A through pipelines L161 and L162, and into the purification column 12B through pipelines L161 and L163. The pipelines L162 and L163 are provided with valves V20 and V21 midway, respectively.

[0031] The pipeline L17 is a path for returning the strongly adsorbable component gas desorbed from the purification columns 12A and 12B to the raw material gas storage tank 1. Specifically, pipeline L17 consists of pipelines L171, L172, and L173, and the gas discharged from purification column 12A passes through pipelines 171 and 173, and the gas discharged from purification column 12B passes through pipelines 172 and 173 and is returned to raw material gas storage tank 1. Valves V18 and V19 are provided midway along the pipelines L171 and L172, respectively.

[0032] As described above, the pressure swing adsorption gas separation apparatus 100 of this embodiment further includes a purification apparatus 300 downstream of the conventionally known gas separation apparatus 200. This makes it possible to recover strongly adsorbable components or weakly adsorbable components at high concentrations and with high recovery rates, thereby achieving improvements in the purity and recovery rate of high-value-added gases.

[0033] <Pressure swing adsorption gas separation method> Next, a pressure swing adsorption gas separation method using the pressure swing adsorption gas separation apparatus 100 of this embodiment will be described. In this embodiment, the gas separation method using the gas separation apparatus 200 may be the same as the method described in Japanese Patent Application Laid-Open No. 2006-061831, and detailed explanations will be omitted, and only the main parts will be explained below.

[0034] <<Gas separation method using gas separation apparatus 200>> In the gas separation method using the gas separation apparatus 200, gas is adsorbed alternately between the lower column 10B and the upper column 10U, and between the lower column 11B and the upper column 11U. Specifically, the lower column 10B and the upper column 10U repeatedly perform the following steps in this order: [adsorption process], [purging process], [lower column depressurization process], [upper column depressurization process], [rinsing process], and [pressure equalization process]. The lower cylinder 11B and the upper cylinder 11U also undergo the same process, but with a half cycle delay.

[0035] That is, when the lower column 10B and the upper column 10U perform the adsorption step, the lower column 11B and the upper column 11U perform the lower column depressurization step, the upper column depressurization step, and the rinsing step in this order. When the lower column 10B and the upper column 10U perform the "purging step," the lower column 11B and the upper column 11U perform the "pressure equalization step." While the lower column 10B and the upper column 10U are performing the lower column depressurization step, the upper column depressurization step, and the rinsing step in this order, the lower column 11B and the upper column 11U are performing the adsorption step. When the lower column 10B and the upper column 10U perform the "pressure equalization step", the lower column 11B and the upper column 11U perform the "purging step".

[0036] The steps performed in lower tube 10B and upper tube 10U are the same as the steps performed in lower tube 11B and upper tube 11U, so the following description will focus on lower tube 10B and upper tube 10U. Although various gases can be used as the source gas in this embodiment, for the sake of convenience, the following description will be given using a mixed gas of xenon and nitrogen as the source gas. In the adsorbent used in this embodiment, the strongly adsorbable component is xenon and the weakly adsorbable component is nitrogen.

[0037] [Adsorption process] In the adsorption step, the mixed gas from the raw material gas storage tank 1 is compressed by the compressor 4 and supplied to the lower column 10B via the pipelines L2 and L4.

[0038] Since the valve V5 is opened to allow communication between the lower column 10B and the upper column 10U, the pressure in the lower column 10B and the upper column 10U rises at approximately the same rate.

[0039] As the mixed gas supplied to the lower column 10B advances to the upper part of the lower column 10B, xenon is preferentially adsorbed, and nitrogen is concentrated in the gas phase. The concentrated nitrogen is introduced from the lower column 10B into the upper column 10U, where trace amounts of xenon contained in the nitrogen are further adsorbed.

[0040] After the pressure in the upper column 10U becomes higher than the pressure in the weakly adsorbed component storage tank 3, the nitrogen further concentrated in the upper column 10U is discharged via pipe L6 to the weakly adsorbed component storage tank 3. The nitrogen in the weakly adsorbed component storage tank 3 is discharged via pipe L7 to the purification device 300 at a flow rate corresponding to the flow rate of nitrogen contained in the raw material gas, and the remaining gas is used as a countercurrent purge gas in the rinsing step.

[0041] [Purge process] In the purge step, valve V1 is closed and valve V2 is opened, thereby changing the gas introduced into lower column 10B to xenon from strong adsorbent reservoir 2. By introducing xenon from strong adsorbent reservoir 2 into lower column 10B, nitrogen co-adsorbed in the adsorbent layer in lower column 10B and nitrogen present in the adsorbent voids are pushed into upper column 10U, resulting in adsorption saturation of lower column 10B with xenon. In addition, by closing valve V7 and opening valve V9, the gas in upper column 10U is introduced into upper column 11U. Because the gas introduced into upper column 11U has a high nitrogen concentration, the xenon in upper column 11U can be pushed down to the bottom of the upper column and lower column 11B.

[0042] During this time, nitrogen continues to be discharged from the less adsorbable component storage tank 3. The nitrogen in the less adsorbable component storage tank 3 is discharged to the purification device 300, as in the adsorption step.

[0043] [Lower tube decompression process] In the lower column depressurization step, valves V3, V5, and V9 are closed, and valves V11 and V12 are opened. As a result, the xenon adsorbed in lower column 10B is recovered into the strongly adsorbable component storage tank 2 via lines L9, L23, and L12 due to the pressure difference between lower column 10B and the strongly adsorbable component storage tank 2.

[0044] The xenon recovered in the strongly adsorbable component storage tank 2 is pressurized by compressor 5 to a flow rate corresponding to the xenon contained in the raw gas, and is extracted as a product from line L13. The remaining xenon is used as a co-current purge gas in the purge step. During this time, the upper column 10U is in a quiescent state because valves V5 and V7 are closed.

[0045] [Upper tube decompression process] In the upper column depressurization step, valve V11 is closed and valves V5 and V10 are opened. This causes a pressure difference between upper column 10U, which was at rest during the lower column depressurization step, and lower column 10B, which has been depressurized, and the gas in upper column 10U flows into lower column 10B.

[0046] The gas introduced into the lower column 10B is recovered in the raw material gas storage tank 1 via the pipes L9, L23, and L11 while purging the inside of the lower column 10B. The gas recovered in the raw material gas storage tank 1 is remixed with the raw material gas introduced from the pipe L1 and supplied again to the lower column during the adsorption step.

[0047] [Rinse process] In the rinsing step, valve V14 is opened. Nitrogen stored in the weakly adsorbed component storage tank 3 is introduced into the upper column 10U via line L8 as a countercurrent purge gas. As the nitrogen introduced into the upper column 10U proceeds to the bottom of the upper column and then to the lower column 10B, it displaces and desorbs the adsorbed xenon. The desorbed gas, which contains a relatively large amount of xenon, is recovered in the source gas storage tank 1 via lines L9, L23, and L11.

[0048] The gas recovered in the raw material gas storage tank 1 is mixed with the raw material gas introduced from the pipe L1 and is supplied again to the lower column during the adsorption step. Here, the nitrogen used as the countercurrent purge gas may be nitrogen extracted from the upper column 11U in the [adsorption step], and introduced directly into the upper column 10U where the [rinsing step] is being performed, without passing through the weakly adsorbed component storage tank 3.

[0049] [Pressure equalization process] In the pressure equalization step, valves V10 and V12 are closed and valve V9 is opened. This allows the gas in upper column 11U to be introduced into upper column 10U. Because the gas introduced into upper column 10U has a high nitrogen concentration, it is possible to push the xenon in upper column 10U downward to the bottom of the upper column and lower column 10B.

[0050] Through the above steps, the gas separation apparatus 200 can separate the strongly adsorbable component and the weakly adsorbable component from the raw material gas. The separated weakly adsorbed components are stored in a weakly adsorbed component storage tank 3 and then discharged to a downstream purification device 300.

[0051] <<Gas Separation Method Using Purification Device 300>> The gas (nitrogen) discharged from the weakly adsorbed component storage tank 3 is introduced into the purification device 300. The gas separation method in the purification device 300 is a gas separation method using a PSA device, in which the gas is alternately adsorbed in the purification column 12A and the purification column 12B.

[0052] Specifically, both purification columns 12A and 12B repeat the adsorption process and the desorption process, but when purification column 12A performs the adsorption process, purification column 12B performs the desorption process, and when purification column 12A performs the desorption process, purification column 12B performs the adsorption process. The steps performed in the refining column 12A and the steps performed in the refining column 12B are the same, so the following description will focus on the refining column 12A and explain each step.

[0053] [Adsorption process] In the adsorption step, the gas mainly composed of the weakly adsorbed component (nitrogen) recovered in the weakly adsorbed component storage tank 3 is supplied to the purification column 12A via the pipe L7. The strongly adsorbed component (xenon) is adsorbed into the gas supplied to the purification column 12A, and the weakly adsorbed component (nitrogen) is discharged to the outside of the system via the pipe L15.

[0054] [Detachment process] In the desorption step, a portion of the nitrogen discharged from purification column 12B is returned to purification column 12A as a countercurrent purge gas via lines L161 and L162. As the nitrogen introduced into purification column 12A advances toward the bottom of purification column 12A, it displaces and desorbs the adsorbed xenon. The desorbed gas containing xenon is recovered in raw material gas storage tank 1 via lines L171 and L173. Note that the xenon-containing gas may be separately separated and recovered at this time.

[0055] After the above steps, the purification device 300 is used to separate and recover trace amounts of strongly adsorbable components contained in the gas mainly composed of weakly adsorbable components recovered in the weakly adsorbable component storage tank 3, and the strongly adsorbable components and weakly adsorbable components in the raw gas are recovered simultaneously.

[0056] The introduction of the raw material gas through the line L1, the introduction of the weakly adsorbed component through the line L7, the discharge of the weakly adsorbed component through the line L15, the discharge of the strongly adsorbed component through the line L13, and the introduction of the gas through the line L17 are carried out continuously regardless of the process.

[0057] However, in semiconductor product or display device manufacturing facilities to which this pressure swing adsorption gas separation method is applied, situations can frequently arise where there is no need to use xenon, i.e., situations where exhaust gas from the manufacturing facility that serves as the raw material gas does not flow in. In such a case, in this pressure swing adsorption gas separation apparatus, the nitrogen discharged from line L7 and the xenon discharged from line L13 are returned to the raw material gas storage tank 1 (not shown), thereby making it possible to stop the supply while maintaining a state in which the product gas can always be supplied.

[0058] According to the pressure swing adsorption gas separation method of this embodiment, in the subsequent stage of a gas separation method using a conventional gas separation apparatus 200, the weakly adsorbed component gas discharged from the gas separation apparatus 200 is purified using a purification apparatus 300. This makes it possible to recover trace amounts of the strongly adsorbed gas contained in the weakly adsorbed component gas discharged from the gas separation apparatus 200, and recover the strongly adsorbed components or weakly adsorbed components at high concentrations and with a high recovery rate, thereby achieving improvements in the purity and recovery rate of high value-added gas.

[0059] [Second embodiment] <Pressure swing adsorption gas separation device> Next, a pressure swing adsorption gas separation apparatus according to a second embodiment of the present invention will be described with reference to the drawings. Explanations of the same parts as those in the first embodiment will be omitted.

[0060] As shown in FIG. 2, a pressure swing adsorption gas separation apparatus 100A of this embodiment differs from the first embodiment in that a TSA (Thermal Swing Adsorption) apparatus is used as a purification device 300A. As a result, in this embodiment, a heater 6 is provided in the pipe line L16.

[0061] <Pressure swing adsorption gas separation method> Unlike the first embodiment, this embodiment uses a TSA device as the refining device 300A, and therefore the desorption step is different from that of the first embodiment. The other steps are the same as those of the first embodiment.

[0062] In the desorption step of this embodiment, the gas discharged from the purifying column 12B passes through the lines L152 and L153, ​​and then branches off and is discharged to the line L16. The gas is then heated by a heater 6 provided in the line L16 and then introduced into the purification column 12A.

[0063] The strongly adsorbable components attached to the adsorbent packed in the purification column 12A are desorbed by the heated gas, and the strongly adsorbable components are recovered and the adsorbent is regenerated.

[0064] In this embodiment, as in the first embodiment, a purification device is provided downstream of the conventional gas separation device 200. This makes it possible to recover strongly adsorbable components or weakly adsorbable components at a high concentration and at a high recovery rate, thereby achieving improvements in the purity and recovery rate of high value-added gas.

[0065] [Third embodiment] <Pressure swing adsorption gas separation device> Next, a pressure swing adsorption gas separation apparatus according to a third embodiment of the present invention will be described with reference to the drawings. Explanations of parts that are the same as those in the first embodiment will be omitted.

[0066] As shown in FIG. 3, a pressure swing adsorption gas separation apparatus 100B of this embodiment differs from the first embodiment in that a single-cylinder PSA apparatus is used as a purification unit 300B. As a result, in this embodiment, a buffer reservoir 7 is provided downstream of the purification column 12A. Specifically, the gas discharged from the purification column 12A passes through the pipe L154 and is stored in the buffer reservoir 7. A portion of the gas stored in the buffer reservoir 7 is discharged to the outside of the system through the pipe L155, and a portion passes through the pipe L164 and is used in the desorption step of the purification column 12A. The pipelines L154 and L164 are provided with valves V24 and V25, respectively.

[0067] <Pressure swing adsorption gas separation method> Unlike the first embodiment, this embodiment uses a single-tube PSA apparatus as the refining apparatus 300B, and therefore differs from the first embodiment mainly in the desorption step. The other steps are the same as those in the first embodiment.

[0068] In the adsorption step of this embodiment, unlike the first embodiment, the gas discharged from the purification column 12A is stored in the buffer storage tank . In the desorption step, the gas stored in the buffer reservoir 7 is introduced into the purification column 12A via the pipeline L164, and the easily adsorbed components adhering to the adsorbent are desorbed.

[0069] In this embodiment, as in the first embodiment, a purification device is provided downstream of the conventional gas separation device 200. This makes it possible to recover strongly adsorbable components or weakly adsorbable components at a high concentration and at a high recovery rate, thereby achieving improvements in the purity and recovery rate of high value-added gas.

[0070] [Fourth embodiment] <Pressure swing adsorption gas separation device> Next, a pressure swing adsorption gas separation apparatus according to a fourth embodiment of the present invention will be described with reference to the drawings. This embodiment is a modification of the third embodiment, and a description of similar parts will be omitted.

[0071] As shown in FIG. 4, a pressure swing adsorption gas separation apparatus 100C of this embodiment differs from the third embodiment in that a single-tube TSA apparatus is used as a purification unit 300C. As a result, in this embodiment, a heater 8 is provided in the pipe line L164.

[0072] <Pressure swing adsorption gas separation method> Unlike the third embodiment, this embodiment uses a single-tube PSA apparatus as the refining apparatus 300C, and therefore the desorption step is different from that of the third embodiment. The other steps are the same as those of the third embodiment.

[0073] In the desorption step of this embodiment, the gas stored in the buffer reservoir tank 7 is led to the pipeline L164. The gas is then heated by the heater 8 provided in the pipeline L164 and then introduced into the purification column 12A.

[0074] The strongly adsorbable components attached to the adsorbent packed in the purification column 12A are desorbed by the heated gas, and the strongly adsorbable components are recovered and the adsorbent is regenerated.

[0075] In this embodiment, as in the first embodiment, a purification device is provided downstream of the conventional gas separation device 200. This makes it possible to recover strongly adsorbable components or weakly adsorbable components at a high concentration and at a high recovery rate, thereby achieving improvements in the purity and recovery rate of high value-added gas.

[0076] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments and can be modified in various ways. For example, the gas separation method using the gas separation apparatus 200 may be carried out through any suitable conventionally known process, and is not limited to the above process. Furthermore, the gas separation method using the purification device 300 is not limited to the above-described embodiment, and separation may be performed through an appropriate process known as a PSA device or a TSA device. Furthermore, in the above embodiment, an example was described in which gas heated by a heater is introduced into the purification column when using a TSA device, but this is not limited to this, and known heating means or heating methods may be used, such as heating the purification column itself. [Example]

[0077] The present invention will be described in detail below using examples and comparative examples. <Comparative Example> First, as a comparative example, the apparatus shown in JP-A-2006-061831 (see FIG. 5) was used to carry out a separation operation using the valve control shown in Table 1.

[0078] The feed gas was a mixture of xenon and nitrogen (xenon concentration 10%), and the flow rate was 2 L / min (all data below were at 0°C and atmospheric pressure). Activated carbon was used as the adsorbent (the easily adsorbed component was xenon, and the less easily adsorbed component was nitrogen).

[0079] The extraction rate of the strongly adsorbed component (xenon) was set to 1 L / min, and the extraction rate of the weakly adsorbed component (nitrogen) was set to 1 L / min. The lower columns (10B, 11B) and upper columns (10U, 11U) were made of stainless steel, 100A (inner diameter 108.3 mm), the adsorbent filling height was 500 mm, and the adsorbent was filled with 2.0 kg of activated carbon. Compressor 4 was a diaphragm compressor and was operated at a flow rate of 40 L / min. Compressor 5 was a diaphragm compressor and was operated at a flow rate of 1 L / min.

[0080] [Table 1]

[0081] When the xenon ratio of the xenon and nitrogen mixed gas stored in the source gas storage tank 1 was changed to 45%, 50%, and 60%, the results shown in Table 2 were obtained.

[0082] [Table 2]

[0083] [Example 1] Next, as Example 1, a separation operation was carried out using the device shown in the first embodiment with the same valve control as in the comparative example. The purification columns 12A and 12B were controlled with the valves shown in Table 3 with the following specifications. The purification columns 12A and 12B were made of stainless steel, 50A (inner diameter 52.5 mm), and the adsorbent filling height was 500 mm. The adsorbent was 0.75 kg of activated carbon.

[0084] [Table 3]

[0085] When the xenon ratio of the xenon and nitrogen mixed gas stored in the source gas storage tank 1 was set to 50% and 60%, the results shown in Table 4 were obtained.

[0086] [Table 4]

[0087] As is clear from the above table, when the xenon concentration in the raw material gas storage tank 1 is the same, it was confirmed that in Example 1, the xenon recovery rate is improved compared to the comparative example, while maintaining the same purity of xenon discharged from pipe L13.

[0088] When the xenon concentration in the source gas storage tank 1 was set to 50%, the results shown in Figure 6 were obtained for the time-dependent changes in the nitrogen concentration in the xenon extracted from the line L13, the xenon concentration in the nitrogen extracted from the line L7, and the xenon concentration in the nitrogen extracted from the line L15.

[0089] These results confirm that the time required from system startup until the xenon purity and xenon recovery rate stabilized was shorter than in the comparative example. If the xenon stored in the highly adsorbable component storage tank is of sufficiently high purity, the nitrogen concentration in the xenon extracted from line L13 does not depend on the elapsed time.

[0090] On the other hand, between the time the system is started and the time the temperature and pressure of the lower and upper columns reach a stable state, the lower and upper columns are unable to adsorb xenon sufficiently, so nitrogen containing a high concentration of xenon is discharged from line L7. After the temperature and pressure of the lower and upper columns stabilize, the storage tank for weakly adsorbed components is gradually replaced with nitrogen, and the xenon concentration in the nitrogen discharged from line L7 decreases over a long period of time. In the line L15, xenon is adsorbed by the purification tube, so the increase in xenon concentration immediately after startup is smaller than in the line L7, and the time required for the xenon concentration to decrease is also shorter.

[0091] [Example 2] Next, using the device shown in the second embodiment, a separation operation was carried out with the same valve control as in the comparative example. The refinery column was controlled by the valves shown in Table 5 with the following specifications. The purification columns (12A, 12B) were made of stainless steel and had a diameter of 300A (inner diameter of 297.9 mm), and the adsorbent was packed to a height of 1500 mm. The adsorbent was 72 kg of X-type zeolite.

[0092] [Table 5]

[0093] When the xenon ratio of the xenon and nitrogen mixed gas stored in the source gas storage tank 1 was set to 50% and 60%, the results shown in Table 6 were obtained.

[0094] [Table 6]

[0095] As is clear from the above results, when the xenon concentration in the raw gas storage tank 1 was the same, it was confirmed that in Example 2, the xenon recovery rate was improved while maintaining the same purity of xenon discharged from pipe L13 compared to the comparative example. It was also confirmed that the time required from the start of the equipment until the xenon purity and xenon recovery rate stabilized was shorter than in the comparative example. [Explanation of symbols]

[0096] DESCRIPTION OF SYMBOLS 1 Raw gas storage tank, 2 Strongly adsorbed component storage tank, 3 Weakly adsorbed component storage tank, 4, 5 Compressor, 6, 8 Heater, 7 Buffer storage tank, 10B, 11B Lower column, 10U, 11U Upper column, 12A, 12B Purification column

Claims

1. a gas containing an easily adsorbed component that is easily adsorbed to a first adsorbent and a poorly adsorbed component that is poorly adsorbed to the first adsorbent is used as a raw material gas; a separation apparatus including a lower column and an upper column filled with the first adsorbent, a raw material gas storage tank for storing a raw material gas, and a strongly adsorbable component storage tank for storing the strongly adsorbable component; a purification column packed with a second adsorbent that is easily adsorbable to the easily adsorbable component and is hardly adsorbable to the poorly adsorbable component, A pressure swing adsorption gas separation method for recovering the strongly adsorbable component and the weakly adsorbable component from the raw material gas, comprising: A pressure swing adsorption gas separation method comprising a separation step of introducing the gas discharged from the separation device into the purification column for separation.

2. The separation step comprises: a step of adsorbing a strongly adsorbable component in the gas discharged from the separation device onto the second adsorbent; and desorbing the strongly adsorbable component adsorbed on the second adsorbent.

2. The pressure swing adsorption gas separation method according to claim 1.

3. 3. The pressure swing adsorption gas separation method according to claim 2, wherein the second adsorbent is heated to desorb the strongly adsorbable component adsorbed on the second adsorbent.

4. A pressure swing adsorption gas separation apparatus that separates a feed gas containing an easily adsorbed component that is easily adsorbed to a first adsorbent and a poorly adsorbed component that is poorly adsorbed to the first adsorbent, a separation apparatus including a lower column and an upper column filled with the first adsorbent, a raw material gas storage tank for storing the raw material gas, and a strongly adsorbable component storage tank for storing the strongly adsorbable component; a purification column packed with a second adsorbent that is easily adsorbable to the easily adsorbable component and is poorly adsorbable to the poorly adsorbable component; a pipeline for introducing the gas discharged from the separation device into the purification column; A pressure swing adsorption gas separation apparatus comprising:

5. 5. The pressure swing adsorption gas separation apparatus according to claim 4, further comprising a pipeline for delivering the gas discharged from the purification column to the raw gas storage tank.

6. 6. The pressure swing adsorption gas separation apparatus according to claim 4, further comprising a heating means for heating the second adsorbent.

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