Pressure Swing Adsorption Gas Purification Equipment

Abstract

To provide a pressure fluctuation adsorption type gas purifier which can suppress the large fluctuation of the flowing state of product gas that flows in a downstream side portion of a pressure control valve in a product gas path.SOLUTION: A pressure fluctuation adsorption type gas purifier comprises a plurality of adsorption towers 1 which generate product gas by adsorbing an adsorption target component other than a purification target gas component from raw material gas. The pressure fluctuation adsorption type gas purifier is configured to repeatedly perform an operation cycle including: an adsorption step of supplying the raw material gas to discharge product gas to a product gas path 5 from the adsorption tower 1 in each of the plurality of adsorption towers 1; a decompression step of discharging residual gas from the adsorption tower 1; a washing step of making the product gas flow through the inside of the adsorption tower; and a pressure rising step of increasing the pressure by supplying the product gas to the adsorption tower 1 in such a state that the operation phases of the plurality of adsorption towers 1 are different from each other. A pressure control valve V which maintains the pressure on the upstream side to the set pressure is provided in the product gas path 5. A washing flow channel 9 which supplies the product gas to the adsorption tower 1 in the washing step is connected to the downstream side of the pressure control valve V in the product gas path 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention is configured to include a plurality of adsorption towers for producing a product gas by adsorbing components to be adsorbed other than the gas components to be purified from a raw material gas onto an adsorbent, and to repeatedly perform an operation cycle in each of the plurality of adsorption towers, the operation cycle including an adsorption step of supplying the raw material gas and discharging a product gas having a high concentration of the gas components to be purified from the adsorption tower into a product gas passage, a depressurization step of discharging residual gas from the adsorption tower, a cleaning step of causing the product gas to flow through the inside of the adsorption tower, and a pressurization step of supplying the product gas to the adsorption tower and pressurizing it, with the operation phases of the plurality of adsorption towers being different from each other; The present invention relates to a pressure swing adsorption type gas purification apparatus in which a pressure control valve for maintaining the upstream pressure at a set pressure is provided in the product gas line. [Background technology]

[0002] Such a pressure swing adsorption type gas purification apparatus will, for example, use reformed gas supplied from a reforming treatment apparatus that steam reforms city gas as a raw material gas to purify a product gas having a high concentration of hydrogen as a gas component to be purified, or will use coal mine gas as a raw material gas to purify a product gas having a high concentration of methane as a gas component to be purified. By providing a pressure control valve in the product gas line for maintaining the upstream pressure at a set pressure, the internal pressure of the adsorption tower can be appropriately maintained at a pressure required for adsorbing the components to be adsorbed onto the adsorbent in the adsorption process, thereby enabling the operating cycle to be carried out appropriately.

[0003] A conventional example of a pressure swing adsorption gas purification apparatus is one in which a cleaning flow path that supplies cleaning gas to an adsorption tower in a cleaning process is connected upstream of a pressure control valve in a product gas path (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6305938 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional pressure swing adsorption type gas purification apparatuses, during the cleaning process, cleaning gas flows from the upstream part of the pressure control valve in the product gas path, which causes a large drop in pressure in the upstream part of the pressure control valve, resulting in a large fluctuation in the pressure in the upstream part of the pressure control valve. As a result, there is an inconvenience that the flow condition (flow rate and pressure) of the product gas flowing in the downstream part of the pressure control valve in the product gas path varies greatly, and an improvement was desired.

[0006] In other words, when the pressure in the upstream portion of the pressure control valve drops, the pressure control valve closes to increase the pressure in the upstream portion. However, when cleaning gas flows from the upstream portion of the pressure control valve, the pressure in the upstream portion of the pressure control valve drops suddenly and significantly, causing the pressure control valve to close in an overshooting manner. As a result, there is an inconvenience that the flow condition (flow rate and pressure) of the product gas flowing in the downstream portion of the pressure control valve in the product gas path fluctuates greatly, and improvement was desired.

[0007] In addition, when the supply amount of the raw material gas is set to a low flow rate and the cleaning gas flows from the upstream portion of the pressure control valve, the pressure control valve overshoots until it closes to the fully closed state, and there is a risk that the flow rate of the product gas flowing through the downstream portion of the pressure control valve in the product gas path will momentarily become zero. Furthermore, when the product gas from the product gas path is supplied to another device by a compressor, if the pressure control valve is fully closed, it can cause problems such as compressor breakdown, so improvement was desired in this regard as well.

[0008] In addition, when using reformed gas supplied from a reforming device that steam-reforms hydrocarbon gases such as city gas as a raw material gas to refine a product gas with a high concentration of hydrogen as a gas component to be refined, if the pressure in the upstream portion of the pressure control valve fluctuates over a large range, the pressure in the internal flow path of the reforming device will also fluctuate greatly. As a result, when mixing steam into the raw material gas, it becomes difficult to mix while maintaining the S / C (steam / carbon ratio) at an appropriate value, which may adversely affect the steam reforming process of the reforming device, and improvement is also desired from this point of view.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a pressure swing adsorption type gas purification device that can suppress large fluctuations in the flow state of the product gas flowing in the downstream portion of the pressure control valve in the product gas path. [Means for solving the problem]

[0010] The pressure swing adsorption type gas purification apparatus of the present invention comprises a plurality of adsorption towers for producing a product gas by adsorbing components to be adsorbed other than the gas components to be purified from a raw material gas onto an adsorbent, and is configured to repeatedly perform an operation cycle in each of the plurality of adsorption towers, the operation cycle including an adsorption step of supplying the raw material gas and discharging a product gas having a high concentration of the gas components to be purified from the adsorption tower into a product gas passage, a depressurization step of discharging remaining gas from the adsorption tower, a cleaning step of causing the product gas to flow through the inside of the adsorption tower, and a pressurization step of supplying the product gas to the adsorption tower and pressurizing it, with the operation phases of the plurality of adsorption towers being different from each other; the product gas passage is connected to a product gas tank that stores the product gas from the adsorption tower; The product gas path includes: The adsorption tower side A pressure control valve is provided to maintain the upstream pressure at a set pressure, and its characteristic configuration is as follows: A cleaning flow path for supplying the product gas to the adsorption tower in the cleaning step is connected to the product gas path downstream of the pressure control valve.

[0011] That is, in the cleaning process, the product gas for cleaning is supplied to the adsorption tower through the cleaning flow path connected to the downstream side of the pressure control valve in the product gas line, so that the pressure in the upstream part of the pressure control valve in the product gas line does not fluctuate even when the cleaning process is performed, and therefore the pressure in the upstream part of the pressure control valve in the product gas line does not fluctuate suddenly and greatly. As a result, the pressure control valve will no longer close in a state that would cause overshoot, thereby suppressing large fluctuations in the flow rate and pressure of the product gas flowing in the downstream portion of the pressure control valve in the product gas path.

[0012] Incidentally, even when using reformed gas supplied from a reforming treatment device that performs steam reforming on hydrocarbon gases such as city gas as raw material gas to refine a product gas having a high concentration of hydrogen as a gas component to be refined, the pressure in the upstream portion of the pressure control valve does not fluctuate over a large range, and therefore the pressure in the internal flow path of the reforming treatment device does not fluctuate greatly either. As a result, when steam is mixed with the raw material gas, it is possible to mix the raw material gas while maintaining the S / C (steam / carbon ratio) at an appropriate value.

[0013] In short, the characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention makes it possible to suppress large fluctuations in the flow state of the product gas flowing in the downstream portion of the pressure control valve in the product gas passage.

[0014] A further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention is a product gas tank that stores the product gas flowing downstream of the pressure control valve in the product gas line, The cleaning flow path is connected to a portion of the product gas line between the pressure control valve and the product gas tank.

[0015] In other words, the flow condition (flow rate and pressure) of the product gas flowing downstream of the pressure control valve will fluctuate due to the operation of the pressure control valve, but because a product gas tank is provided to store the product gas flowing downstream of the pressure control valve, large fluctuations in the flow condition (flow rate and pressure) of the product gas flowing downstream of the pressure control valve can be suppressed.

[0016] As a result, in the cleaning step, the cleaning product gas can be caused to flow appropriately through the cleaning flow path, and the cleaning step can be carried out well while causing the cleaning product gas to flow appropriately.

[0017] In short, according to a further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention, the cleaning process can be performed well while the product gas for cleaning is appropriately flowed.

[0018] A further characteristic feature of the pressure swing adsorption gas purification apparatus of the present invention is that a flow rate control unit is provided for controlling a flow rate regulating valve that adjusts the flow rate of the product gas flowing through the cleaning flow path based on a detection value of a flow rate sensor that detects the flow rate of the product gas flowing through the cleaning flow path, so as to maintain the flow rate of the product gas flowing through the cleaning flow path at a set target value during the cleaning process.

[0019] That is, in the cleaning process, the flow rate control valve is controlled based on the flow rate sensor detection value, so that the flow rate of the product gas flowing through the cleaning flow path is maintained at a set target value, and the product gas for cleaning can be flowed to the adsorption tower performing the cleaning process without excess or deficiency.

[0020] Therefore, the product gas for cleaning can be caused to flow just enough through the adsorption tower undergoing the cleaning step, so that the adsorption tower undergoing the cleaning step can be cleaned more appropriately.

[0021] In short, according to a further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention, the adsorption tower in which the cleaning step is carried out can be cleaned more appropriately.

[0022] A further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention is that a start-up operation cleaning flow path is connected to a location upstream of the pressure control valve in the product gas path, a cleaning state switching unit that switches between a startup operation state in which the product gas flows through the startup cleaning flow path and a steady operation state in which the product gas flows through the cleaning flow path; The start-up cleaning flow path and the cleaning flow path The point is that it is provided.

[0023] In other words, when resuming operation from a stopped state, the cleaning process is first performed in the startup operation state in which the product gas is flowing through the startup operation cleaning flow path, and then the cleaning process can be performed in the steady operation state in which the product gas is flowing through the cleaning flow path, so that the cleaning process can be performed appropriately even when operation is resumed.

[0024] In other words, when operation is resumed from a stopped state, the product gas does not flow to the location downstream of the pressure control valve in the product gas path, and the product gas for cleaning cannot be properly flowed through the cleaning flow path. However, by performing the cleaning process in a startup operation state in which product gas flows through the startup operation cleaning flow path connected to the upstream location of the pressure control valve in the product gas path, even when operation is resumed from a stopped state, it is possible to properly clean the adsorption tower performing the cleaning process by flowing a sufficient amount of product gas for cleaning to the adsorption tower performing the cleaning process.

[0025] In short, according to a further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention, the adsorption tower undergoing the cleaning process can be properly cleaned even when operation is resumed after being stopped.

[0026] A further characteristic feature of the pressure swing adsorption gas purification apparatus of the present invention is that the operation control unit, which repeats the operation cycle with the operating phases of the multiple adsorption towers differing from one another, controls the cleaning state switching unit so that, when starting operation from a stopped state, the cleaning process is performed in the startup operation state and then the cleaning process is performed in the steady operation state.

[0027] In other words, when starting operation from a stopped state, the operation control unit, which repeats operation cycles with the operating phases of multiple adsorption towers differing from one another, first performs a cleaning process in a startup operation state in which product gas flows through the startup operation cleaning flow path, and then performs a cleaning process in a steady operation state in which product gas flows through the cleaning flow path.

[0028] In this way, when starting operation from a stopped state, the operation control unit first performs the cleaning process in the startup operation state, and then performs the cleaning process in the steady operation state, so that the cleaning process can be performed well when operation is resumed from a stopped state.

[0029] In short, according to a further characteristic configuration of the pressure swing adsorption gas purification apparatus of the present invention, the cleaning step can be carried out satisfactorily when the operation is restarted after being stopped. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram showing a pressure swing adsorption type hydrogen production device. [Diagram 2] FIG. 2 is a diagram illustrating an operation cycle in a unit processing period. [Diagram 3] FIG. 2 is a diagram showing the gas flow state in the first step. [Figure 4] FIG. 13 is a diagram showing the gas flow state in the second step. [Diagram 5] FIG. 13 is a diagram showing the gas flow state in the third step. [Figure 6] FIG. 11 is a diagram showing the startup operation state of the second step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Overall configuration of pressure swing adsorption type hydrogen production device) As shown in FIG. 1, the illustrated pressure swing adsorption hydrogen production apparatus (an example of a pressure swing adsorption gas purification apparatus) is configured to use reformed gas, which is obtained by steam reforming a hydrocarbon gas CG such as city gas in a reformer K, as a raw material gas, and to produce a product gas having a high concentration of hydrogen components using four adsorption towers 1.

[0032] The reformed gas contains methane, carbon dioxide, carbon monoxide, and nitrogen in addition to the hydrogen component, and methane, carbon dioxide, carbon monoxide, and nitrogen are adsorbed by the adsorbent in the adsorption tower 1 as the components to be adsorbed other than hydrogen. In other words, the adsorption tower 1 is configured to adsorb components to be adsorbed other than the hydrogen component as the gas components to be purified from the reformed gas onto the adsorbent to purify the product gas.

[0033] More specifically, an operation control unit M is provided that controls the operation of the four adsorption towers 1. The operation control unit M is configured to repeatedly perform an operation cycle in each of the multiple (four) adsorption towers 1, the operation cycle including an adsorption process in which reformed gas is supplied and a product gas having a high concentration of hydrogen components is discharged from the adsorption tower 1 to the product gas line 5, a depressurization process in which residual gas is discharged from the adsorption tower 1 to the off-gas discharge line 4, a cleaning process in which the product gas is caused to flow through the inside of the adsorption tower 1, and a pressure increase process in which the product gas is supplied to the adsorption tower 1 and pressure increase is performed, with the operation phases of the multiple adsorption towers 1 being different from each other, thereby causing the adsorption target components other than the hydrogen component to be adsorbed to the adsorbent from the reformed gas containing the hydrogen component to generate a product gas.

[0034] Specifically, as shown in FIG. 1, four adsorption towers 1, namely, Tower A, Tower B, Tower C, and Tower D, are provided, and a raw material gas supply passage 3 for supplying reformed gas pumped from a reformer K and an off-gas exhaust passage 4 for exhausting off-gas are connected to the lower part of the four adsorption towers 1.

[0035] At the top of the four adsorption towers 1, there are provided a product gas delivery passage 5A that connects the four adsorption towers 1 to each other, a pressurization passage 6A that connects the four adsorption towers 1 to each other, and a cleaning passage 7A that connects the four adsorption towers 1 to each other. The product gas passage 5 is provided in a state of being connected to the product gas delivery passage 5A.

[0036] A pressure control valve V is provided in the product gas line 5 to maintain the upstream pressure at a set pressure. The pressure control valve V is of well-known configuration and will not be described in detail here, but the opening degree of the pressure control valve V is controlled by a regulator Va to which the pressure upstream of the pressure control valve V is input so as to maintain the upstream pressure at a set pressure. Further, a product gas tank T2 for storing the product gas flowing downstream of the pressure control valve V in the product gas passage 5 is provided.

[0037] A cleaning flow path 9, which supplies the product gas as a cleaning gas to the adsorption tower 1 in the cleaning step, is connected to the product gas path 5 downstream of the pressure control valve V. That is, in this embodiment, the cleaning flow path 9 is connected to a flow path portion of the product gas path 5 between the pressure control valve V and the product gas tank T2. In addition, a start-up operation cleaning flow path 7 is connected to a location upstream of the pressure control valve V in the product gas path 5. A cleaning state switching unit Q is provided for switching between a startup operation state in which the product gas flows through the startup operation cleaning flow path 7 and a normal operation state in which the product gas flows through the cleaning flow path 9.

[0038] The reformed gas to be supplied to the raw material gas supply passage 3 is configured to be supplied to the raw material gas supply passage 3 using the supply pressure of the compressor 2 which supplies the hydrocarbon gas CG to the reformer K. Corresponding to the four adsorption towers 1, raw material gas supply valves A1, B1, C1, and D1 for opening and closing the raw material gas supply passage 3, and off-gas exhaust valves A5, B5, C5, and D5 for opening and closing the off-gas exhaust passage 4 are provided, respectively. In addition, a main gas valve 3A is provided downstream of the reformer K in the raw material gas supply passage 3, which is closed when the hydrogen gas production operation is stopped.

[0039] A pressurization passage 6 for directing a portion of the product gas flowing through the product gas passage 5 to the pressurization communication passage 6A is provided so as to connect the product gas passage 5 and the pressurization communication passage 6A. The pressure boosting passage 6A and the cleaning passage 7A are also used as pressure equalizing passages, and a pressure equalizing connection passage 8 is connected between the pressure boosting passage 6A and the cleaning passage 7A.

[0040] Corresponding to each of the four adsorption towers 1, there are provided product gas delivery valves A2, B2, C2, D2 which interrupt communication with the product gas delivery communication passage 5A, first on-off valves A3, B3, C3, D3 which interrupt communication with the pressurization communication passage 6A, and second on-off valves A4, B4, C4, D4 which interrupt communication with the cleaning communication passage 7A.

[0041] The pressurizing passage 6 is provided with a pressurizing on-off valve 6a for opening and closing the pressurizing passage 6, and a pressurizing regulating valve 6b for regulating the opening degree of the pressurizing passage 6. The pressure equalizing connection passage 8 is provided with a pressure equalizing on-off valve 8a for opening and closing the pressure equalizing connection passage 8, and a pressure equalizing adjustment valve 8b for adjusting the opening degree of the pressure equalizing connection passage 8.

[0042] The cleaning flow path 9 is provided with a cleaning on-off valve 9a that opens and closes the cleaning flow path 9, a flow rate control valve 9b that adjusts the flow rate of the product gas, and a flow rate sensor 9c that detects the flow rate of the product gas flowing through the cleaning flow path 9. Similarly, the start-up operation cleaning flow path 7 is provided with a start-up operation cleaning on-off valve 7a which opens and closes the start-up operation cleaning flow path 7, a start-up operation flow control valve 7b which adjusts the flow rate of the product gas, and a start-up operation flow sensor 7c which detects the flow rate of the product gas flowing through the start-up operation cleaning flow path 7. In this embodiment, the cleaning state switching section Q is configured with a cleaning on-off valve 9a and a startup operation cleaning on-off valve 7a as main components.

[0043] An off-gas tank T1 that recovers the off-gas and supplies the recovered off-gas to a burner B serving as a combustion device is provided in the off-gas discharge passage 4. Although a detailed description of the burner B is omitted, the burner B is intended to raise the temperature of the reforming reaction tube of the reformer provided in the above-mentioned reformer K.

[0044] The reforming device K has a well-known configuration and will not be described in detail, but includes a desulfurizer that desulfurizes the hydrocarbon gas CG, a steam supply unit that supplies steam to the desulfurized hydrocarbon gas CG, a reformer that steam reforms the desulfurized hydrocarbon gas CG to which the steam has been supplied, and a CO converter that converts carbon monoxide contained in the reformed gas from the reformer. The supply pressure from the compressor 2 causes the gas (hydrocarbon gas CG and reformed gas after reforming) to flow through a flow path that serially connects the desulfurizer, reformer, and CO converter, and is supplied to the raw material gas supply path 3. Incidentally, the amount of steam supplied to the desulfurized hydrocarbon gas CG is adjusted so that the S / C (steam / carbon ratio) is appropriate.

[0045] (Details of the driving cycle) In the pressure swing adsorption hydrogen production apparatus of this embodiment, an operation control unit M controls valves such as the above-mentioned raw gas supply valves A1, B1, C1, D1, etc., to repeatedly perform an operation cycle including an adsorption process, a pressure equalization discharge process, a pressure reduction process, a cleaning process, a pressure equalization receiving process, and a pressure increase process in each of multiple (four) adsorption towers 1, with the operation phases of the four adsorption towers 1 being different from one another.

[0046] In other words, as shown in FIG. 2, during a unit treatment period, one of the four adsorption towers 1 performs an adsorption process, the adsorption tower 1 performing the process following the adsorption process performs a pressure equalization discharge process including a front-stage discharge process and a rear-stage discharge process, the adsorption tower 1 performing the process following the pressure equalization discharge process performs a desorption process including a depressurization process, a cleaning process, and the rear-stage acceptance process of the pressure equalization acceptance process, and the adsorption tower 1 performing the process following the desorption process performs a pressure recovery process including a front-stage acceptance process and a pressurization process of the pressure equalization acceptance process.

[0047] Incidentally, FIG. 2 illustrates an example in which tower A performs the adsorption process, tower B performs the pressure recovery process, tower C performs the desorption process, and tower D performs the pressure equalization discharge process. In other words, when four adsorption towers 1 are provided, four unit treatment periods will be provided, and although not shown in the figure, during a unit treatment period in which tower B performs the adsorption process, tower C performs the pressure recovery process, tower D performs the desorption process, and tower A performs the pressure equalization discharge process.

[0048] Similarly, during the unit treatment period in which Tower C performs the adsorption process, Tower D performs the pressure recovery process, Tower A performs the desorption process, and Tower B performs the pressure equalization discharge process. In addition, during the unit treatment period in which Tower D performs the adsorption process, Tower A performs the pressure recovery process, Tower B performs the desorption process, and Tower C performs the pressure equalization discharge process.

[0049] The unit processing period is divided into three steps, from the first step to the third step. For example, the length of the first step is set to 20 seconds, the length of the second step is set to 160 seconds, and the length of the third step is set to 20 seconds.

[0050] Each of the four adsorption towers 1 sequentially performs the adsorption process, the pressure equalization discharge process, the desorption process, and the pressure recovery process. In the following explanation, we will explain the case where, of the four adsorption towers 1, Tower A performs the adsorption process, Tower B performs the pressure recovery process, Tower C performs the desorption process, and Tower D performs the pressure equalization discharge process.

[0051] Next, the gas flow state in the first to third steps will be explained based on Figures 3 to 6. In each figure, the flow paths in the gas flow state where gas flows are shown with thick lines, and the flow paths in the gas non-flow state where gas does not flow are shown with thin lines. As shown in FIGS. 3 to 6, in the first to third steps, the raw material gas supply valve A1 and the product gas delivery valve A2 corresponding to tower A are opened, and the adsorption step is performed for tower A during the unit treatment period.

[0052] As shown in FIG. 3, in the first step, the second on-off valve D4 of tower D, the first on-off valve B3 of tower B, and the pressure equalization on-off valve 8a are each opened to supply the internal gas of tower D to tower B. This process corresponds to the front-stage discharge process of the pressure equalization discharge process for tower D, and corresponds to the front-stage receiving process of the pressure equalization receiving process for tower B. In the first step, the off-gas discharge valve C5 of the C tower is opened to perform a depressurization step in which the C tower in the desorption step communicates with the product gas tank T2.

[0053] In the subsequent start-up operation of the second step, as shown in FIG. 6 , the first on-off valve B3 and the pressurization on-off valve 6a of tower B are opened to perform a pressurization process in which the product gas is supplied to tower B, and the off-gas discharge valve C5 of tower C, the second on-off valve C4 of tower C, and the start-up operation cleaning on-off valve 7a are each opened to perform a cleaning process in which the product gas is caused to flow through the inside of tower C. Incidentally, the off-gas discharged from tower C is supplied to burner B while being recovered in off-gas tank T1.

[0054] Similarly, in the steady operation of the second step, as shown in FIG. 4, the first on-off valve B3 and the pressurization on-off valve 6a of the B tower are opened to perform the pressurization process of supplying the product gas to the B tower, and the off-gas discharge valve C5 of the C tower, the second on-off valve C4 of the C tower, and the wash on-off valve 9a of the C tower are opened to perform the wash process of causing the product gas to flow through the inside of the C tower. Incidentally, the off-gas discharged from tower C is supplied to burner B while being recovered in off-gas tank T1.

[0055] In the third step, as shown in FIG. 5, the second on-off valve D4 of the D tower, the first on-off valve C3 of the C tower, and the pressure equalization on-off valve 8a are each opened to supply the internal gas of the D tower to the C tower. This process corresponds to the latter-stage discharge process of the pressure equalization discharge process for the D tower, and corresponds to the latter-stage receiving process of the pressure equalization receiving process for the C tower. Incidentally, in the third step, the off-gas stored in the off-gas tank T1 is supplied to the burner B.

[0056] (Switching from startup operation to normal operation) A concentration measuring unit N is provided for measuring the concentration of the component to be adsorbed contained in the product gas generated in each of the multiple (four) adsorption towers 1. In this embodiment, the concentration of carbon monoxide (CO) is measured as the concentration of the component to be adsorbed. That is, the concentration measurement unit N is configured using a CO sensor that measures the concentration of carbon monoxide (CO).

[0057] In this embodiment, the concentration measurement unit N is provided to measure the concentration of the component to be adsorbed in the product gas flowing through the product gas passage 5 connected to each of the multiple (four) adsorption towers 1. In other words, the concentration measurement unit N is provided at a location in the product gas passage 5 near the connection with the product gas delivery communication passage 5A. The detection information of the concentration measuring unit N is input to the operation control unit M.

[0058] The operation control unit M is configured to correspond the product gas flowing through the product gas path 5 to the adsorption tower 1 that produced the product gas, based on the progress of the operation cycle in each of the multiple (four) adsorption towers 1. In other words, the unit processing period from the first to third steps is 200 seconds, and each time the unit processing period elapses, product gas from a different adsorption tower 1 flows through the product gas path 5. However, during the unit processing period, one adsorption tower 1 performs the adsorption process, so product gas from the same adsorption tower 1 flows through the product gas path 5.

[0059] Therefore, the operation control unit M is configured to correspond, based on the passage of time, between the product gas flowing through the product gas path 5 and the adsorption tower 1 performing the adsorption process, thereby corresponding the concentration of the component to be adsorbed in the product gas flowing through the product gas path 5 to the adsorption tower 1 that produced the product gas. Incidentally, there is a delay of several seconds before the product gas discharged from the adsorption tower 1 flows to the location where the concentration measurement unit N is installed, and so this delay time must be taken into consideration when correlating the relationship between the product gas flowing through the product gas path 5 and the adsorption tower 1 performing the adsorption process over time.

[0060] As shown in FIG. 1, a discharge passage 10 is provided downstream of the pressure control valve V in the product gas path 5, which discharges to the outside unfinished product gas whose concentration of the component to be adsorbed measured by the concentration measuring unit N is higher than a set concentration (e.g., 0.1 ppm), and a discharge valve 10A is provided for opening and closing the discharge passage 10. Furthermore, a product gas valve 5a for opening and closing the product gas path 5 is provided in the product gas path 5 downstream of the branch point of the discharge path 10.

[0061] Then, the operation control section M controls the opening and closing of the cleaning on-off valve 9a and the startup operation cleaning on-off valve 7a to carry out the cleaning process. In other words, when the operation control unit M performs startup operation to start up the system from a stopped operation state in which operation has been stopped, as shown in Figure 6, the cleaning on-off valve 9a is closed, the startup operation cleaning on-off valve 7a is opened, the product gas valve 5a is closed, and the release valve 10A is opened, so that the cleaning process is performed in a state in which the product gas is flowing through the startup operation cleaning flow path 7. During the start-up operation, the unfinished product gas is discharged to the outside through the discharge passage 10.

[0062] In addition, when the operation control unit M performs steady operation after startup operation, it is configured to open the cleaning on-off valve 9a, close the startup operation cleaning on-off valve 7a, open the product gas valve 5a, and close the release valve 10A to perform the cleaning process while causing the product gas to flow through the cleaning flow path 9.

[0063] In other words, when the operation control unit M performs startup operation from a stopped state in which operation has been stopped, steps 1 to 3 are repeated, but the cleaning process is performed in a state in which the product gas is caused to flow through the startup operation cleaning flow path 7, and the product gas discharged through the pressure control valve V is discharged through the discharge path 10.

[0064] The operation control unit M is configured to switch from the startup operation state to the steady operation state when all of the concentrations of the components to be adsorbed measured by the concentration measuring unit N for each of the four adsorption towers 1 become lower than the set concentration during startup operation. Specifically, in this embodiment, when start-up operation is being performed, as soon as all of the concentrations of the components to be adsorbed measured by the concentration measuring units N for each of the four adsorption towers 1 become lower than the set concentrations, the product gas valve 5a is opened and the release valve 10A is closed to store the product gas in the product gas tank T2, but until the unit treatment period has been repeated a set number of times, the cleaning process is performed with the cleaning on-off valve 9a closed and the start-up operation cleaning on-off valve 7a open.

[0065] In other words, the cleaning process is executed with the cleaning on-off valve 9a closed and the cleaning on-off valve 7a for startup operation open until the product gas is stored in the product gas tank T2 at a set amount or more, and when the product gas is stored in the product gas tank T2 at a set amount or more, the cleaning process is executed with the cleaning on-off valve 9a opened and the cleaning on-off valve 7a for startup operation closed. Although not shown in the figure, the product gas stored in the product gas tank T2 is used for various purposes, such as being supplied to gas consuming equipment using a product gas supply compressor.

[0066] In addition, when startup operation is performed, the operation control unit M is configured to control the startup operation flow rate regulating valve 7b based on the detection information of the startup operation flow rate sensor 7c in order to maintain the flow rate of the product gas flowing through the startup operation cleaning flow path 7 at a set target value. Similarly, during steady-state operation, the operation control unit M is configured to control the flow rate regulating valve 9b based on detection information from the flow rate sensor 9c in order to maintain the flow rate of the product gas flowing through the cleaning flow path 9 at a set target value. In this embodiment, an example is shown in which the flow control unit P that controls the flow control valve 9b and the startup operation flow control valve 7b is configured by the operation control unit M, but the flow control unit P and the operation control unit M may be provided separately.

[0067] Incidentally, a configuration for detecting the production volume of the product gas can be adopted in which the detection value of a flow sensor provided in the flow path portion between the pressure control valve V in the product gas path 5 and the start-up operation cleaning flow path 7 is subtracted from the detection value of a flow sensor 9c. Alternatively, as another configuration, a flow sensor can be provided in the flow path portion downstream of the branching position of the cleaning flow path 9 in the product gas path 5, and the production volume of the product gas can be determined from the detection value of the flow sensor.

[0068] [Another embodiment] Next, other embodiments will be listed. (1) In the above embodiment, the concentration of carbon monoxide (CO) is measured as the concentration of the component to be adsorbed. However, the present invention may be embodied in a form in which the concentration of another component to be adsorbed, such as nitrogen (N), is measured.

[0069] (2) In the above embodiment, a product gas having a high concentration of hydrogen components is produced from a reformed gas as a feed gas. However, the pressure swing adsorption gas purification apparatus of the present invention can be used to produce a product gas having a high concentration of methane from coal mine gas as a feed gas, and can be applied to a variety of gases as feed gases.

[0070] (3) In the above embodiment, a pressure swing adsorption hydrogen production apparatus having four adsorption towers 1 was described. However, the present invention can also be applied to pressure swing adsorption hydrogen production apparatus having three or five or more adsorption towers 1.

[0071] (4) In the above embodiment, an example was given of a case in which one concentration measuring unit N is provided for multiple (four) adsorption towers 1, but the present invention may also be implemented in a form in which a concentration measuring unit N is provided separately for each of multiple (four) adsorption towers 1.

[0072] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Explanation of symbols]

[0073] 1 Adsorption tower 5 Product gas line 7 Start-up cleaning flow path 9 Washing Channel 9b Flow control valve 9c Flow Sensor T2 Product Gas Tank Q Cleaning state switching unit V Pressure Control Valve M Operation control unit N concentration measurement unit

Claims

1. the system is provided with a plurality of adsorption towers for producing a product gas by adsorbing components to be adsorbed other than the gas components to be purified from a raw material gas onto an adsorbent, and each of the plurality of adsorption towers is configured to repeatedly perform an operation cycle including an adsorption step of supplying the raw material gas and discharging a product gas having a high concentration of the gas components to be purified from the adsorption tower into a product gas passage from the adsorption tower, a depressurization step of discharging residual gas from the adsorption tower, a cleaning step of causing the product gas to flow through the inside of the adsorption tower, and a pressurization step of supplying the product gas to the adsorption tower and pressurizing it, with the operation phases of the plurality of adsorption towers being different from each other; the product gas line is connected to a product gas tank that stores the product gas from the adsorption tower, and a pressure control valve is provided in the product gas line to maintain a pressure on the upstream side, i.e., the adsorption tower side, at a set pressure, in the pressure swing adsorption type gas purification apparatus, a cleaning flow path for supplying the product gas to the adsorption tower in the cleaning step, the cleaning flow path being connected to the downstream side of the pressure control valve in the product gas path;

2. a product gas tank for storing the product gas flowing downstream of the pressure control valve in the product gas path; 2. The pressure swing adsorption gas purification system according to claim 1, wherein the cleaning flow path is connected to a flow path portion of the product gas line between the pressure control valve and the product gas tank.

3. 3. The pressure swing adsorption gas purification apparatus according to claim 1, further comprising a flow control unit that controls a flow rate regulating valve that adjusts the flow rate of the product gas flowing through the cleaning flow path based on a detection value of a flow sensor that detects the flow rate of the product gas flowing through the cleaning flow path in the cleaning step, so as to maintain the flow rate of the product gas flowing through the cleaning flow path at a set target value.

4. a start-up flushing flow path is connected to the product gas path at a location upstream of the pressure control valve; 4. The pressure swing adsorption gas purification apparatus according to claim 1, wherein a cleaning state switching unit that switches between a startup operation state in which the product gas is caused to flow through the startup operation cleaning flow path and a steady operation state in which the product gas is caused to flow through the cleaning flow path is provided in the startup operation cleaning flow path and the cleaning flow path.

5. 5. The pressure swing adsorption gas purification apparatus according to claim 4, wherein an operation control unit that repeats the operation cycle with the operation phases of the plurality of adsorption towers being different from one another controls the cleaning state switching unit so that, when starting operation from a stopped state, the cleaning process is performed in the startup operation state and then the cleaning process is performed in the steady operation state.

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