Gas separation recovery method and gas separation recovery facility

Abstract

To provide a gas separation recovery method to efficiently separate and recover target gas containing target gas composition from raw material gas and a gas separation recovery facility for the same.SOLUTION: A gas separation recovery method is a method separating and recovering target gas containing target gas composition from raw material gas through pressure swing adsorption in which the gas separation recovery method includes adsorption process and desorption process and does not include cleaning process between the adsorption process and the desorption process. In the desorption process, adsorption towers 11a, 11b are evacuated by a vacuum pump 14a to desorb impurity gas composition except the target gas composition from a discharge side of off gas of the adsorption towers 11a, 11b, and the adsorption towers 11a, 11b are evacuated by a vacuum pump 14b to desorb the target gas composition from a supply side of the raw material gas of the adsorption towers 11a, 11b so as to separate and recover the target gas.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas separation and recovery method and a gas separation and recovery facility. [Background technology]

[0002] Conventionally, pressure swing adsorption (PSA) has been used as a method for separating predetermined gas components contained in a raw gas (see, for example, Patent Document 1). The PSA method is a separation method that utilizes the fact that the amount of gas components adsorbed to an adsorbent varies depending on the gas type and its partial pressure, and typically includes a step of adsorbing the gas components to an adsorbent (adsorption step), a step of supplying a portion of the desorbed gas desorbed in another adsorption tower as a cleaning gas in order to increase the adsorption rate of the gas components to the adsorbent (cleaning step), and a step of desorbing the adsorbed gas components from the adsorbent to recover the gas (desorption step).

[0003] The PSA method is applied in various fields and is often used as a method for producing highly concentrated gas by adsorbing one component contained in a raw gas. However, since the power required for gas separation is large, methods that do not involve a washing step have been proposed in order to reduce the amount of power used (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-144818 [Patent Document 2] Patent No. 6677181 Specification Summary of the Invention [Problem to be solved by the invention]

[0005] The PSA methods disclosed in Patent Documents 1 and 2 above are effective in reducing the power consumption of vacuum pumps and the like because the desorbed gas is not reused as a cleaning gas. Meanwhile, in the gas separation method described in Patent Document 2, in the adsorption step, a raw gas is supplied from the top of an adsorption tower filled with an adsorbent, and the target gas component is adsorbed onto the adsorbent. An off-gas containing non-adsorbed gas components that were not adsorbed onto the adsorbent is discharged from the bottom of the adsorption tower. In the desorption step, as shown in FIG. 1, the inside of the adsorption tower is depressurized using a vacuum pump connected to the off-gas discharge side of the adsorption tower. Impurity gas components other than the target gas component are first desorbed, and the impurity gas containing the impurity gas component is discharged and recovered. Next, the target gas component adsorbed onto the adsorbent is desorbed, and the target gas containing the target gas component is discharged and recovered.

[0006] Although the method described in Patent Document 2 is effective for removing impurity gas components, it is inefficient in terms of desorption of the target gas components. This is because the target gas components are adsorbed in large amounts at the top of the adsorbent packed bed to which the raw gas is supplied during the adsorption process, while the target gas components are adsorbed in small amounts at the bottom of the adsorbent packed bed. Therefore, when the target gas components are desorbed from the bottom of the adsorption tower during the desorption process, some of the desorbed target gas components are re-adsorbed onto the adsorbent at the bottom of the adsorbent packed bed. Because the interior of the adsorption tower is gradually depressurized by a vacuum pump, the target gas components re-adsorbed on the adsorbent at the bottom of the adsorbent packed bed are eventually desorbed and separated and recovered. However, surplus electricity is required to re-desorb the re-adsorbed target gas components. This reduces the power consumption reduction effect achieved by not using a cleaning gas.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its object is to propose a method and equipment for more efficiently separating and recovering a target gas containing a target gas component from a raw material gas. [Means for solving the problem]

[0008] The present invention, which solves the above problems, is as follows. [1] A method for separating and recovering a target gas containing a target gas component from a raw material gas by pressure swing adsorption, comprising: an adsorption step of supplying the raw material gas to an adsorption tower filled with an adsorbent to adsorb the target gas component onto the adsorbent, and discharging an off-gas containing a non-adsorbed gas component that was not adsorbed onto the adsorbent from the adsorption tower; and a desorption step of desorbing the target gas component adsorbed onto the adsorbent in the adsorption step to recover the target gas containing the target gas component, and no cleaning step of supplying a target gas discharged from another adsorption tower as a cleaning gas to the adsorption tower between the adsorption step and the desorption step, In the desorption step, the inside of the adsorption tower is depressurized by a vacuum pump, impurity gas components other than the target gas component are desorbed from the off-gas discharge side of the adsorption tower, and the target gas component is desorbed from the raw gas supply side of the adsorption tower, thereby separating and recovering the target gas. A gas separation and recovery method.

[0009] [2] A method for separating and recovering a target gas containing a target gas component from a raw material gas by pressure swing adsorption, comprising: an adsorption step of supplying the raw material gas to an adsorption tower filled with an adsorbent to adsorb the target gas component onto the adsorbent, and discharging an off-gas containing a non-adsorbed gas component that was not adsorbed onto the adsorbent from the adsorption tower; and a desorption step of desorbing the target gas component adsorbed onto the adsorbent in the adsorption step to recover the target gas containing the target gas component, but not including a cleaning step of supplying a portion of the target gas discharged from another adsorption tower as a cleaning gas to the adsorption tower between the adsorption step and the desorption step, a vacuum pump that desorbs the target gas component or an impurity gas component other than the target gas component is provided, a first intake line and a first line valve connected to the vacuum pump are provided on the off-gas discharge side of the adsorption tower, and a second intake line and a second line valve connected to the vacuum pump are provided on the raw material gas supply pipe side of the adsorption tower; In the desorption step, the opening degrees of the first line valve and the second line valve are changed for each of a plurality of divided time periods, the inside of the adsorption tower is depressurized by the vacuum pump to desorb the impurity gas component from the off-gas discharge side of the adsorption tower, the inside of the adsorption tower is depressurized by the vacuum pump to desorb the target gas component from the raw material gas supply side of the adsorption tower, and the impurity gas containing the impurity gas component and the target gas are independently separated and recovered.

[0010] [3] The adsorption tower is a vertical adsorption tower in which gas flows vertically, In the adsorption step, the raw material gas is introduced from an upper part of the adsorption tower and the off-gas is discharged from a lower part of the adsorption tower; The gas separation and recovery method according to [1] or [2], wherein in the desorption step, the impurity gas components are desorbed from the lower part of the adsorption tower, and the target gas components are desorbed from the upper part of the adsorption tower.

[0011] [4] A pressure relief pipe having a pressure relief valve for reducing the pressure inside the adsorption tower is connected to the adsorption tower, The gas separation and recovery method according to any one of [1] to [3], further comprising a pressure relief step between the adsorption step and the desorption step, in which the pressure relief valve is opened to reduce the pressure inside the adsorption tower.

[0012] [5] The gas separation and recovery method according to any one of [1] to [4], wherein during a certain period of time in the desorption step, the desorption of the target gas component is carried out simultaneously from the supply side of the raw gas and the discharge side of the off-gas.

[0013] [6] A gas separation and recovery system for separating and recovering a target gas containing a target gas component from a raw gas by a pressure swing adsorption method, the system comprising: an adsorption tower filled with an adsorbent that adsorbs the target gas component; a raw gas supply pipe that supplies the raw gas to the adsorption tower; and an off-gas discharge pipe that discharges an off-gas containing a non-adsorbed gas component that was not adsorbed by the adsorbent from the adsorption tower; and the system does not comprise a cleaning gas supply pipe that supplies a portion of the target gas discharged from another adsorption tower to the adsorption tower as a cleaning gas, a first vacuum pump that desorbs impurity gas components other than the target gas component, a first intake line that is connected to the first vacuum pump, and a first line valve are provided on the off-gas discharge pipe side of the adsorption tower; and a second vacuum pump that desorbs the target gas component, a second intake line that is connected to the second vacuum pump, and a second line valve are provided on the raw material gas supply pipe side of the adsorption tower.

[0014] [7] A gas separation and recovery system for separating and recovering a target gas containing a target gas component from a raw gas by a pressure swing adsorption method, the system comprising: an adsorption tower filled with an adsorbent that adsorbs the target gas component; a raw gas supply pipe that supplies the raw gas to the adsorption tower; and an off-gas discharge pipe that discharges an off-gas containing a non-adsorbed gas component that was not adsorbed by the adsorbent from the adsorption tower; and no cleaning gas supply pipe that supplies a portion of the target gas discharged from another adsorption tower to the adsorption tower as a cleaning gas, a vacuum pump that desorbs the target gas component or an impurity gas component other than the target gas component is provided, a first intake line and a first line valve connected to the vacuum pump are provided on the off-gas discharge side of the adsorption tower, and a second intake line and a second line valve connected to the vacuum pump are provided on the raw material gas supply pipe side of the adsorption tower; A gas separation and recovery system characterized in that a first branch line and a third line valve for recovering an impurity gas containing the impurity gas component are provided on the exhaust side of the vacuum pump, and a second branch line and a fourth line valve for recovering the target gas are provided.

[0015] [8] The adsorption tower is a vertical adsorption tower in which gas flows vertically, The gas separation and recovery facility according to [6] or [7], wherein the first intake line is connected to a lower portion of the adsorption tower, and the second intake line is connected to an upper portion of the adsorption tower.

[0016] [9] The separation and recovery facility according to any one of [6] to [8], wherein the adsorption tower is connected to a pressure relief pipe having a pressure relief valve for reducing the pressure inside the adsorption tower. [Effects of the Invention]

[0017] According to the present invention, a target gas containing a target gas component can be more efficiently separated and recovered from a raw material gas. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing an example of a conventional gas separation facility. [Figure 2] 1 is a diagram showing a preferred example of a gas separation facility according to the present invention. [Figure 3] FIG. 3 is a diagram illustrating a gas separation method according to the present invention using the equipment shown in FIG. 2. [Figure 4] FIG. 1 is a diagram showing how the target gas component is desorbed simultaneously from the raw gas supply side and the off-gas discharge side. [Figure 5] FIG. 1 is a diagram showing another preferred example of a gas separation facility according to the present invention. [Figure 6] FIG. 6 is a diagram illustrating a gas separation method according to the present invention using the equipment shown in FIG. 5. [Figure 7] FIG. 4 is a diagram showing the relationship between the suction pressure of a vacuum pump and the gas flow rate. [Figure 8] FIG. 4 is a diagram showing the relationship between the suction pressure of a vacuum pump and power consumption. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a preferred example of a gas separation system according to the present invention. The gas separation system 1 shown in FIG. 2 is a system for separating and recovering a target gas containing a target gas component from a raw gas by pressure swing adsorption. The gas separation system 1 includes two adsorption towers 11 (11a, 11b) filled with an adsorbent that adsorbs the target gas component, a raw gas supply pipe 12 (12a, 12b) that supplies the raw gas to the adsorption towers 11 (11a, 11b), and an off-gas discharge pipe 13 (13a, 13b) that discharges off-gas containing non-adsorbed gas components that were not adsorbed by the adsorbent from the adsorption towers 11 (11a, 11b). Note that the gas separation system 1 does not include a cleaning gas supply pipe that supplies a portion of the target gas discharged from the other adsorption towers to the adsorption towers 11 (11a, 11b) as cleaning gas.

[0020] A vacuum pump (first vacuum pump) 14a for desorbing impurity gas components other than the target gas component is provided on the off-gas discharge pipe 13 side of the adsorption tower 11, and a first suction line 15a and first line valves V1 (V1a, V1b) connected to the first vacuum pump 14a. A vacuum pump (second vacuum pump) 14b for desorbing the target gas component is provided on the raw material gas supply pipe 12 side of the adsorption tower 11 (11a, 11b), and a second suction line 15b and second line valves V2 (V2a, V2b) connected to the second vacuum pump 14b.

[0021] The raw material gas supply pipe 12 is provided with valves 16 (16a, 16b) for controlling the flow of raw material gas in the raw material gas supply pipe 12. In addition, the off-gas discharge pipe 13 is provided with valves 17 (17a, 17b) for controlling the flow of off-gas in the off-gas discharge pipe 13.

[0022] The gas separation equipment 1 shown in FIG. 2 is a two-tower type having two adsorption towers 11, but it may be a one-tower type having one adsorption tower 11 or a three-tower or more type having three or more adsorption towers 11.

[0023] As shown in FIG. 2, the adsorption tower 11 is preferably a vertical adsorption tower in which gas flows vertically. The first intake line 15a is connected to the bottom of the adsorption tower 11, and the second intake line 15b is connected to the top of the adsorption tower 11. This configuration allows the gas flow direction within the adsorption tower 11 to be downward during the adsorption process. Furthermore, the impurity gas flows downward, while the target gas flows upward during the desorption process. When the supply of raw gas begins during the adsorption process and when desorption of impurity gas components begins during the desorption process, the gas pressure is relatively high, and the gas flow rate momentarily increases. Therefore, if the gas flow direction is upward when the supply of raw gas begins during the adsorption process and when desorption of impurity gas components begins during the desorption process, flooding may occur at the top of the adsorbent packed bed, resulting in the risk of some of the adsorbent being scattered. In this regard, by connecting the first intake line 15a to the bottom of the adsorption tower 11 and the second intake line 15b to the top of the adsorption tower 11, the gas flow direction is downward when the raw gas is supplied in the adsorption process and when the impurity gas components are desorbed in the desorption process, and the gas flow direction is upward when the target gas components are desorbed in the desorption process. As a result, the pressure inside the adsorption tower 11 is reduced during desorption of the target gas components, resulting in a lean gas flow. Since the gas flow rate is also relatively small, flooding of the adsorbent packed bed is unlikely to occur. Therefore, it is preferable to configure the gas separation equipment 1 shown in Figure 2 so that the target gas flows upward during the desorption process.

[0024] As shown in FIG. 2, it is also preferable to connect a pressure relief pipe 18 having a pressure relief valve B1 (B1a, B1b) for reducing the pressure inside the adsorption tower 11 to the adsorption tower 11. This allows a pressure relief step to be performed in which the pressure relief valve B1 of the pressure relief pipe 18 is opened to reduce the pressure inside the adsorption tower 11 before the adsorption tower 11 is depressurized by the vacuum pump 14 during the desorption step. In PSA operation, the feed gas is often supplied to the adsorption tower 11 under pressure during the adsorption step. Therefore, at the start of the desorption step, impurity gas components can be desorbed from the adsorbent by pressure relief alone and discharged as a stripped gas. Therefore, as shown at the bottom of the adsorption tower 11 in FIG. 2, by connecting the pressure relief pipe 18 to the adsorption tower 11 and recovering the impurity gas through a gas line that does not pass through the vacuum pump 14, the power consumption of the vacuum pump 14 can be reduced. The pressure relief pipe 18 can also be connected to a pipe downstream of the vacuum pump 14a.

[0025] The operation of the gas separation equipment 1 will now be described with reference to Fig. 3. First, in the adsorption step, valves 16 and 17 are opened, and the other valves are closed. A raw material gas is supplied from the raw material gas supply pipe 12 to the adsorption tower 11, and the target gas components contained in the raw material gas are adsorbed onto the adsorbent. At the same time, off-gas containing non-adsorbed gas components that were not adsorbed onto the adsorbent is discharged from the off-gas discharge pipe 13.

[0026] Next, preferably, in a pressure release step (not shown), valves 16 and 17 are closed, and pressure release valve B1 is opened to reduce the pressure inside adsorption tower 11, desorbing the impurity gas components adsorbed on the adsorbent, and discharging the evaporated gas containing the impurity gas components through pressure release pipe 18.

[0027] Next, the desorption process is divided into several sections, and in a first time period (desorption process 1), the pressure release valve B1 is closed, the first line valve V1 is opened, and the inside of the adsorption tower 11 is depressurized by the first vacuum pump 14a to desorb impurity gas components other than the target gas component, and the impurity gas containing the impurity gas components is discharged from the first intake line 15a. Note that the "desorption process" referred to here refers to a process in which the impurity gas or the target gas is desorbed from the adsorbent by depressurizing using the vacuum pump 14, and then separated and recovered.

[0028] Next, during the second time period (desorption step 2), with valve V1 closed and second line valve V2 open, the pressure inside the adsorption tower 11 is reduced by the second vacuum pump 14b, the target gas components are desorbed, and the target gas containing the target gas components is discharged from the second intake line 15b.

[0029] In addition, using the equipment shown in Figure 3, in desorption step 2, the target gas component can be desorbed simultaneously from the raw gas supply side and the off-gas discharge side. In the suction-type PSA (also called "VPSA" or "VSA") method, a vacuum pump 14 is used to desorb the target gas component, but as the adsorption tower 11 becomes larger, the impact of pressure loss in the adsorbent packed bed becomes greater. Therefore, when desorbing the target gas component from the adsorbent packed bed of such a large adsorption tower 11, the amount of target gas desorbed decreases due to the impact of pressure loss. Therefore, as shown in Figure 4, by simultaneously desorbing the target gas component from the raw gas supply side and the off-gas discharge side, the pressure difference between the top and bottom of the adsorption tower 11 can be reduced, thereby increasing the amount of target gas component desorbed.

[0030] Thus, in the present invention, the desorption direction of the impurity gas component (downward of the adsorption tower in the example shown in FIG. 2 ) and the desorption direction of the target gas component (upward of the adsorption tower in the example shown in FIG. 2 ) are different. Desorption of the impurity gas component from the raw gas supply side (i.e., from above the adsorption tower 11 in the example shown in FIG. 2 ) is undesirable because the impurity gas flows through the target gas adsorption section, lowering the partial pressure of the target gas and promoting desorption of the target gas component. In this regard, by making the desorption direction of the impurity gas component and the desorption direction of the target gas component different as in the present invention, it is possible to prevent the impurity gas from flowing through the adsorbent region where the target gas component is adsorbed and to prevent the target gas component from being re-adsorbed by the adsorbent below the packed bed inside the adsorption tower 11. In this way, the target gas can be efficiently separated and recovered from the raw gas.

[0031] In this way, in the gas separation system 1 according to the present invention, the target gas component is simultaneously desorbed from the upper and lower parts of the adsorption tower 11, thereby reducing re-adsorption of the target gas component onto the adsorbent and improving the recovery amount of the target gas component in the raw gas. Furthermore, by reducing the pressure difference inside the adsorption tower 11, the power consumption of the vacuum pump 14 per unit amount of target gas recovered can also be reduced.

[0032] Figure 5 shows another preferred example of a gas separation system according to the present invention. In the gas separation system 2 shown in Figure 5, the first intake line 15a and the second intake line 15b of the gas separation system 1 shown in Figure 2 are connected to one vacuum pump 14. On the exhaust side of the vacuum pump 14, a first branch line 19 and a fifth line valve V5 are provided for recovering an impurity gas containing impurity gas components, and a second branch line 20 and a sixth line valve V6 are provided for recovering a target gas.

[0033] By using the gas separation equipment 2 shown in FIG. 5, the openings of the line valves V5 and V6 can be changed for each of a plurality of divided time periods during the desorption process, and the impurity gas and the target gas can be separated and recovered independently from the off-gas discharge side and the raw material gas supply side of the adsorption tower 11.

[0034] In the desorption process, impurity gas components with weak adsorption power tend to desorb first, while target gas components with strong adsorption power tend to desorb later. This tendency is particularly pronounced in zeolites, for which the adsorption isotherm (the relationship between pressure and adsorption amount at a certain temperature) of the target gas component is nonlinear. To effectively utilize this characteristic in gas separation, the gas line used for desorption of impurity gas components and the gas line used for desorption of target gas components are switched depending on the time period, particularly using a line valve.

[0035] The operation of the gas separation equipment 2 will now be described with reference to Fig. 6. First, in the adsorption step, valves 16 and 17 are opened, and the other valves are closed. The raw material gas is supplied from the raw material gas supply pipe 12 to the adsorption tower 11, and the target gas components contained in the raw material gas are adsorbed by the adsorbent. At the same time, the off-gas containing the non-adsorbed gas components that were not adsorbed by the adsorbent is discharged from the off-gas discharge pipe 13.

[0036] Next, preferably, in a pressure release step (not shown), valves 16 and 17 are closed, and pressure release valve B1 is opened to reduce the pressure inside adsorption tower 11, desorbing the impurity gas components adsorbed on the adsorbent, and discharging the evaporated gas containing the impurity gas components through pressure release pipe 18.

[0037] Next, the desorption process is divided into several sections, and in the first time period (desorption process 1), the pressure release valve B1 is closed, the third line valve V3 is opened, the fourth line valve V4 is closed, the fifth line valve V5 is opened, and the sixth line valve V6 is closed. With this, the inside of the adsorption tower 11 is depressurized by the vacuum pump 14, and impurity gas components other than the target gas component are desorbed. The impurity gas containing the impurity gas components is discharged from the first intake line 15a and recovered from the first branch line 19.

[0038] Next, during the second time period of the desorption process (desorption process 2), the third line valve V3 is closed, the fourth line valve V4 is open, the fifth line valve V5 is closed, and the sixth line valve V6 is open. With this, the inside of the adsorption tower 11 is depressurized by the vacuum pump 14, and the target gas components are desorbed. The target gas is then discharged from the second intake line 15b and recovered from the second branch line 20.

[0039] In the desorption process, impurity gas components with weak adsorption power tend to desorb first, while target gas components with strong adsorption power tend to desorb later. This tendency is particularly pronounced in zeolites, for which the adsorption isotherm (the relationship between pressure and adsorption amount at a certain temperature) of the target gas component is nonlinear. To effectively utilize this characteristic in gas separation, the gas line used for desorption of impurity gas components and the gas line used for desorption of target gas components are switched depending on the time period, particularly by using a line valve. In this way, impurity gases and target gases can be separated and recovered independently. [Example]

[0040] Using the conditions shown in Table 1, CO2 was separated from the raw material gas by the conventional method shown in Figure 1 in the conventional example, and by the method of the present invention shown in Figure 4 in the inventive example.

[0041] [Table 1]

[0042] Figure 7 shows the relationship between the suction pressure of the vacuum pump and the gas flow rate. In the comparative example, the suction pressure from the top of the adsorption tower was 7 kPa, and referring to Figure 7, the flow rate of the gas discharged from the top of the adsorption tower was 1010 m 3 In contrast, in the example of the present invention, the suction pressure from the top of the adsorption tower was 6 kPa, and referring to Figure 7, the flow rate of the gas discharged from the top of the adsorption tower was 1005 m 3 / h. As a result, the amount of target gas components desorbed from the top of the adsorption tower decreased by about 1%. On the other hand, in the comparative example, the suction pressure from the bottom of the adsorption tower was 4 kPa, and referring to Figure 7, the flow rate of gas discharged from the bottom of the adsorption tower was 950 m 3 In contrast, in the example of the present invention, the suction pressure from the bottom of the adsorption tower was 6 kPa, and referring to Figure 7, the flow rate of the gas discharged from the bottom of the adsorption tower was 1005 m 3 / h. As a result, the amount of target gas components desorbed from the bottom of the adsorption tower increased by approximately 6%. From these results, overall, the invention example was able to increase the desorption amount of target gas components by approximately 5% compared to the comparative example.

[0043] Figure 8 shows the relationship between the suction pressure of the vacuum pump and the power consumption. 3 This was obtained from the performance curve of a 45kW / h (rated power 45kW) (see Shigaki, N. et al., Energy 2018, 11, 900). For the comparative example, the suction pressure from the top of the adsorption tower was 7kPa, while for the inventive example, the suction pressure from the top of the adsorption tower was 6kPa. As a result, referring to Figure 8, the power consumption of the vacuum pump increased by approximately 30%. On the other hand, for the comparative example, the suction pressure from the bottom of the adsorption tower was 4kPa, while for the inventive example, the suction pressure from the bottom of the adsorption tower was 6kPa. As a result, referring to Figure 8, the power consumption of the vacuum pump decreased by approximately 38%. From the above results, overall, the inventive example reduced pressure loss and reduced the power consumption of the vacuum pump by approximately 8% compared to the comparative example. [Industrial Applicability]

[0044] According to the present invention, a target gas containing a target gas component can be more efficiently separated and recovered from a raw material gas. [Explanation of symbols]

[0045] 1,2 Gas separation equipment 11,11a, 11b Adsorption tower 12, 12a, 12b Raw material gas supply pipe 13, 13a, 13b Off-gas exhaust piping 14, 14a, 14b Vacuum pump 15a First intake line 15b Second intake line 16, 16a, 16b, 17, 17a, 17b valves 18 Pressure relief pipe 19 First Branch Line 20 Second Branch Line V1,V1a,V1b,V2,V2a,V2b,V3,V3a,V3b,V4,V4a,V4b,V5,V6 Line valve

Claims

1. A method for separating and recovering a target gas containing a target gas component from a raw material gas by pressure swing adsorption, the method comprising: an adsorption step of supplying the raw material gas to an adsorption tower filled with an adsorbent to adsorb the target gas component onto the adsorbent, and discharging from the adsorption tower an off-gas containing a non-adsorbed gas component that was not adsorbed onto the adsorbent; and a desorption step of desorbing the target gas component adsorbed onto the adsorbent in the adsorption step to recover the target gas containing the target gas component, but not including a cleaning step of supplying a target gas discharged from another adsorption tower as a cleaning gas to the adsorption tower between the adsorption step and the desorption step, In the desorption step, the inside of the adsorption tower is depressurized by a vacuum pump, impurity gas components other than the target gas component are desorbed from the off-gas discharge side of the adsorption tower, and the target gas component is desorbed from the raw gas supply side of the adsorption tower, thereby separating and recovering the target gas. A gas separation and recovery method.

2. A method for separating and recovering a target gas containing a target gas component from a raw material gas by pressure swing adsorption, the method comprising: an adsorption step of supplying the raw material gas to an adsorption tower filled with an adsorbent to adsorb the target gas component onto the adsorbent, and discharging from the adsorption tower an off-gas containing a non-adsorbed gas component that was not adsorbed onto the adsorbent; and a desorption step of desorbing the target gas component adsorbed onto the adsorbent in the adsorption step to recover the target gas containing the target gas component, but not including a cleaning step of supplying a portion of the target gas discharged from another adsorption tower as a cleaning gas to the adsorption tower between the adsorption step and the desorption step, a vacuum pump that desorbs the target gas component or an impurity gas component other than the target gas component is provided, a first intake line and a first line valve connected to the vacuum pump are provided on the off-gas discharge side of the adsorption tower, and a second intake line and a second line valve connected to the vacuum pump are provided on the raw material gas supply pipe side of the adsorption tower, In the desorption step, the opening degrees of the first line valve and the second line valve are changed for each of a plurality of divided time periods, the inside of the adsorption tower is depressurized by the vacuum pump to desorb the impurity gas component from the off-gas discharge side of the adsorption tower, the inside of the adsorption tower is depressurized by the vacuum pump to desorb the target gas component from the raw material gas supply side of the adsorption tower, and the impurity gas containing the impurity gas component and the target gas are independently separated and recovered.

3. The adsorption tower is a vertical adsorption tower in which gas flows vertically, In the adsorption step, the raw material gas is introduced from an upper part of the adsorption tower and the off-gas is discharged from a lower part of the adsorption tower; 3. The gas separation and recovery method according to claim 1, wherein in the desorption step, the impurity gas components are desorbed from a lower portion of the adsorption tower, and the target gas components are desorbed from an upper portion of the adsorption tower.

4. a pressure relief pipe having a pressure relief valve for reducing the pressure inside the adsorption tower is connected to the adsorption tower; 3. The gas separation and recovery method according to claim 1, further comprising a pressure relief step between the adsorption step and the desorption step, in which the pressure relief valve is opened to reduce the pressure inside the adsorption tower.

5. 2. The gas separation and recovery method according to claim 1, wherein the desorption of the target gas component is carried out simultaneously from the feed gas supply side and the off-gas discharge side during a certain time period in the desorption step.

6. A gas separation and recovery system for separating and recovering a target gas containing a target gas component from a raw gas by a pressure swing adsorption method, the system comprising: an adsorption tower filled with an adsorbent that adsorbs the target gas component; a raw gas supply pipe that supplies the raw gas to the adsorption tower; and an off-gas discharge pipe that discharges an off-gas containing a non-adsorbed gas component that was not adsorbed by the adsorbent from the adsorption tower; and the gas separation and recovery system does not include a cleaning gas supply pipe that supplies a portion of the target gas discharged from another adsorption tower to the adsorption tower as a cleaning gas, a first vacuum pump that desorbs impurity gas components other than the target gas component, and a first suction line and a first line valve that are connected to the first vacuum pump, are provided on the off-gas discharge piping side of the adsorption tower; and a second vacuum pump that desorbs the target gas component, and a second suction line and a second line valve that are connected to the second vacuum pump, are provided on the raw material gas supply piping side of the adsorption tower.

7. A gas separation and recovery system for separating and recovering a target gas containing a target gas component from a raw gas by a pressure swing adsorption method, the system comprising: an adsorption tower filled with an adsorbent that adsorbs the target gas component; a raw gas supply pipe that supplies the raw gas to the adsorption tower; and an off-gas discharge pipe that discharges an off-gas containing a non-adsorbed gas component that was not adsorbed by the adsorbent from the adsorption tower; and the gas separation and recovery system does not include a cleaning gas supply pipe that supplies a portion of the target gas discharged from another adsorption tower to the adsorption tower as a cleaning gas, a vacuum pump that desorbs the target gas component or an impurity gas component other than the target gas component is provided, a first intake line and a first line valve connected to the vacuum pump are provided on the off-gas discharge side of the adsorption tower, and a second intake line and a second line valve connected to the vacuum pump are provided on the raw material gas supply pipe side of the adsorption tower, A gas separation and recovery system characterized in that a first branch line and a third line valve for recovering an impurity gas containing the impurity gas component are provided on the exhaust side of the vacuum pump, and a second branch line and a fourth line valve for recovering the target gas are provided.

8. The adsorption tower is a vertical adsorption tower in which gas flows vertically, 8. The gas separation and recovery facility according to claim 6, wherein the first intake line is connected to a lower portion of the adsorption tower, and the second intake line is connected to an upper portion of the adsorption tower.

9. 8. The gas separation and recovery facility according to claim 6, wherein a pressure relief pipe having a pressure relief valve for reducing the pressure inside the adsorption tower is connected to the adsorption tower.

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