JP4669506B2 - How to stop gas production equipment - Google Patents

Description

  The present invention relates to a method for stopping a gas manufacturing apparatus that manufactures a gas with less impurities by a PSA (Pressure Swing Adsorption) mechanism.

  2. Description of the Related Art Conventionally, a technique for producing a gas with few impurities by adsorbing and removing impurities by a PSA mechanism using a plurality of adsorption towers is known. In relation to this technique, a technique has been proposed in which impurities are released from an adsorption tower when a gas production apparatus (PSA mechanism) is started (see Patent Document 1). In addition, in order to improve the startability at the next restart, after the stop signal is input, operation is performed up to a preset stop position (for example, the completion position of the adsorption process or the completion position of the depressurization process) A technique of stopping after continuing is proposed (see Patent Document 2).

JP 2005-272598 A JP 2005-220283 A

  However, in the technique of Patent Document 1, impurities remain in the adsorption tower from the time of stoppage until the next start-up, and thus the remaining impurities diffuse in the adsorption tower and are produced at the next start-up. May contain impurities. Further, in the technique of Patent Document 2, after a stop signal is input, it is necessary to continue operation to a predetermined stop position set in advance, and to continue to produce gas that is not required.

  Therefore, the present invention provides a gas production apparatus stop method capable of suitably reducing the impurities contained in the gas produced at the next startup while stopping the gas production when a stop signal is input. Is an issue.

As a means for solving the above-mentioned problems, the present invention is a method for stopping a gas production apparatus that comprises two or more adsorption towers and produces gas by a PSA mechanism, and at least 1 after a stop signal is input. Residual gas from one adsorption tower is supplied to the other adsorption tower, and the first pressure equalization step in which the pressure between the adsorption towers is substantially the same, and the adsorption tower to which the residual gas is supplied in the first pressure equalization step is depressurized. After the first depressurization step and the first depressurization step, a second equalized pressure is supplied by supplying the residual gas of the adsorption tower that has not been depressurized to the depressurized adsorption tower so that the pressure between the adsorption towers is substantially the same. And a second depressurizing step for depressurizing the adsorption tower supplied with the residual gas in the second pressure equalizing step .

According to such a gas production apparatus stopping method, after a stop signal for stopping the operation of the PSA mechanism is input, the gas production is stopped, and the residual gas of at least one adsorption tower is transferred to another adsorption tower. The pressure between the adsorption towers is made substantially the same (first pressure equalization step), that is, before the stop signal is issued, the residual gas of the adsorption tower that adsorbs impurities and purifies the gas with few impurities is removed. Then, the pressure is supplied to other adsorption towers that are performing cleaning or the like by depressurization to make the pressure of the residual gas uniform between the adsorption towers.
Then, the adsorption tower supplied with the residual gas is depressurized (first depressurization step), that is, the adsorbent in the adsorption tower is removed by discharging the gas of the adsorption tower supplied with the residual gas to the outside. be able to. Thereby, the impurities contained in the produced gas can be reduced at the next startup.
Note that the depressurization of the adsorption tower means that the gas in the adsorption tower is exhausted to lower the pressure, and the adsorbed substance (impurities such as carbon dioxide in the embodiment described later) is externally removed by the exhausted gas. Means that the adsorption tower is washed.

According to such a gas production apparatus stopping method, after the first depressurization step, the residual gas of the adsorption tower that has not been depressurized is supplied to the depressurized adsorption tower, and the pressure between the adsorption towers is made substantially the same. (Second pressure equalization step), by depressurizing the adsorption tower to which the residual gas was supplied in the second pressure equalization step (second pressure desorption step), The adsorbate can be removed.
After that, it is preferable to make the pressure between the adsorption towers substantially the same, then depressurize the adsorption tower supplied with the residual gas, and remove the adsorbate from the adsorption tower.

The two or more adsorption towers include a first adsorption tower and a second adsorption tower, and in the first pressure equalizing step, open a pressure equalizing valve that connects the first adsorption tower and the second adsorption tower, Residual gas of the first adsorption tower is supplied to the second adsorption tower, the pressures of the first adsorption tower and the second adsorption tower are substantially the same, and the pressure equalizing valve in the first depressurization step after closing the open de valve of the first adsorption tower, and depressurization of the first adsorption tower in the second pressure equalization step, after closing the removal valve of the first adsorption tower, the pressure equalizing valve In the second depressurization step, the residual gas of the second adsorption tower is supplied to the first adsorption tower, the pressures of the first adsorption tower and the second adsorption tower are substantially the same , after closing the equalizing valve, the second opening of de valve of the adsorption tower, gas, characterized in that that push de the second adsorption tower A stop process of the manufacturing apparatus.

According to such a gas production apparatus stopping method, after a stop signal for stopping the operation of the PSA mechanism is input, the gas production is stopped. Then, the pressure equalizing valve is opened, the residual gas of the first adsorption tower is supplied to the second adsorption tower, and the pressures of the first adsorption tower and the second adsorption tower are made substantially the same (first pressure equalization step). Next, after closing the pressure equalizing valve, the desorption valve of the first adsorption tower is opened and the first adsorption tower is depressurized (first depressurization step), so that the adsorbate of the first adsorption tower can be removed.
Then, after closing the pressure reducing valve of the first adsorption tower, the pressure equalizing valve is opened, the residual gas of the second adsorption tower is supplied to the first adsorption tower, and the pressure between the first adsorption tower and the second adsorption tower is increased. Substantially the same (second pressure equalization step). Then, after closing the pressure equalizing valve, the adsorbate in the second adsorption tower can be removed by opening the depressurization valve in the second adsorption tower and depressurizing the second adsorption tower (second depressurization step).
Thus, the impurities in each adsorption tower can be discharged from both adsorption towers of the first adsorption tower and the second adsorption tower by effectively utilizing the residual gas that has been conventionally discharged and disposed after stopping.

  The gas production apparatus stopping method is characterized in that when the stop signal is input, the pressure of the first adsorption tower is higher than the pressure of the second adsorption tower.

According to such a method for stopping the gas production apparatus, when a stop signal is input, the pressure in the first adsorption tower is higher than the pressure in the second adsorption tower. Thereby, the residual gas of a 1st adsorption tower can be supplied to a 2nd adsorption tower using the pressure of a 1st adsorption tower. Note that when the stop signal is input, since the adsorption is performed in the first adsorption tower, the pressure in the first adsorption tower becomes higher than the pressure in the second adsorption tower.
Thereafter, by depressurizing the first adsorption tower (adsorption tower supplied with residual gas), the adsorbate can be quickly discharged to the outside before the adsorbate diffuses.

  In the depressurizing step of the adsorption tower, a part of the residual gas in the adsorption tower that has not been depressurized is supplied to the depressurized adsorption tower.

According to such a gas production apparatus stopping method, in the step of depressurizing the adsorption tower (the first depressurization step and the second depressurization step), the adsorption tower that is not depressurized is supplied to the depressurized adsorption tower. The adsorbed material in the desorbing adsorption tower can be pushed out (purged) by the residual gas. In addition, it is preferable that the flow rate of the residual gas supplied from the adsorption tower that is not depressurized to the depressurized adsorption tower is set to a small flow rate by an orifice or the like.
Further, since the adsorbed material is removed while effectively using the residual gas of the adsorption tower that has not been depressurized in this way, it is not necessary to introduce a new gas for removing the adsorbed material into the depressurized adsorption tower.

  Further, the gas production apparatus stopping method is characterized in that the pressure equalization and depressurization are repeated in each adsorption tower until the pressure in each adsorption tower reaches a predetermined pressure.

According to such a gas production apparatus stopping method, the pressure equalization and depressurization are repeated in each adsorption tower until the pressure in each adsorption tower reaches a predetermined pressure (for example, atmospheric pressure). Can be reliably removed, and the pressure equalization and depressurization in each adsorption tower can be prevented from continuing for a long time.
The predetermined pressure is set to a pressure at which this gas does not flow, for example, with the pressure of the gas remaining in each adsorption tower as a driving force.
In addition, for each repetition, the residual amount of impurities remaining in each adsorption tower is separately measured in advance, and based on the measurement result, the repetition number of the pressure equalization step and the depressurization step is set to a predetermined number in advance. It is also possible to repeat the pressure equalization step and the depressurization step according to the predetermined number of times set.

  According to the present invention, when a stop signal is input, a gas production apparatus stop method is provided that can stop gas production and suitably reduce impurities contained in the gas produced at the next startup. Can do.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. In the first embodiment and the second embodiment to be described later, a hydrogen production apparatus 1 that produces hydrogen (gas) with a small amount of impurities is exemplified by the PSA mechanism. The hydrogen produced in this way is supplied as a fuel gas to, for example, the anode of a fuel cell mounted on a fuel cell vehicle. However, the use of hydrogen (fuel gas) is not limited to this, and may be used for combustion.

  The hydrogen production apparatus 1 shown in FIG. 1 adsorbs impurities such as carbon dioxide and water vapor in a raw material gas mainly containing hydrogen by a PSA mechanism, that is, in the first adsorption tower 10A and the second adsorption tower 10B, This is an apparatus for producing high-purity hydrogen by alternately repeating adsorption / removal of impurities. The raw material gas is obtained by steam reforming a raw fuel such as natural gas or methanol and removing carbon monoxide from the reformed gas.

≪Normal operation of hydrogen production equipment≫
First, regarding the normal operation of the hydrogen production apparatus 1, with reference to FIGS. 1 and 2, impurities are adsorbed by the first adsorption tower 10A and the impurities (adsorbed material) adsorbed by the second adsorption tower 10B are depressurized. The case where it is removed will be described.

The source gas is introduced into the lower part of the first adsorption tower 10A through the compressor 21 and the first supply valve 11A. The introduced source gas flows vertically upward in the first adsorption tower 10A, and the impurities are adsorbed by an adsorbent (zeolite, activated carbon, etc.) loaded in the first adsorption tower 10A.
And the hydrogen which became high purity by adsorb | sucking an impurity is supplied to the exterior (for example, hydrogen tank) via the 1st discharge valve 12A and the pressure-holding valve 22 from the upper part of 10 A of 1st adsorption towers. The first pressure equalizing valve 13A and the first pressure reducing valve 14A are closed. The pressure holding valve 22 is a back pressure valve, and controls the adsorption pressure in the first adsorption tower 10A.

On the other hand, the second depressurization valve 14B is opened while the second supply valve 11B, the second discharge valve 12B, and the second pressure equalizing valve 13B are closed, and the residual gas in the second adsorption tower 10B is transferred to the second depressurization valve. It is discharged to the combustion section 23 via 14B. Thus, the residual gas is supplied to the combustion unit 23, whereby the second adsorption tower 10B is depressurized, and the residual gas flows out of the second adsorption tower 10B, so that the adsorbent of the second adsorption tower 10B. The impurities adsorbed on the second adsorption tower 10B are removed, and the second adsorption tower 10B is washed.
It should be noted that impurities such as carbon dioxide according to the first embodiment mainly adsorb to the adsorbent below vertically because hydrogen having a small specific gravity flows vertically upward in the first adsorption tower 10A and the second adsorption tower 10B. ing. Moreover, the combustion part 23 burns the residual gas and impurities discharged | emitted by being depressurized in this way.

  When the adsorption in the first adsorption tower 10A, the depressurization of the second adsorption tower 10B, and the removal of impurities are completed, the first adsorption tower 10A is switched from adsorption to depressurization, the adsorbed impurities are removed, and the second The adsorption tower 10B is switched from depressurization to adsorption and switched to production of high purity hydrogen (see FIG. 2).

≪How to stop hydrogen production equipment≫
Next, a method for stopping the hydrogen production apparatus 1 will be described with reference to FIGS.
When the controller 30 (control means) detects an OFF signal of the switch 31 that operates the hydrogen production apparatus 1, the process shown in the flowchart of FIG. 3 starts. The controller 30 is a control device that electronically controls the hydrogen production apparatus 1, and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, and controls various devices according to programs stored therein. Control and execute various processes.

  In addition, here, the source gas is supplied to the first adsorption tower 10A, the impurities are adsorbed, and high-purity hydrogen is being produced, and the switch 31 is turned off during the depressurization of the second adsorption tower 10B. The case is illustrated. Therefore, when the OFF signal (stop signal) of the switch 31 is input to the controller 30, the gas pressure in the first adsorption tower 10A is higher than the gas pressure in the second adsorption tower 10B (FIG. 4).

In step S101, the controller 30 controls all the valves (the first supply valve 11A, the second supply valve 11B, the first discharge valve 12A, the second discharge valve 12B, the first pressure equalizing valve 13A, the second pressure equalizing valve 13B, the first The pressure release valve 14A and the second pressure release valve 14B) are closed.
In parallel with this, the controller 30 stops the compressor 21 and stops the production of hydrogen (gas) with less impurities.

<First pressure equalization step-pressure equalization of the first and second adsorption towers (first pressure equalization step)>
In step S102, the controller 30 opens the first pressure equalizing valve 13A and the second pressure equalizing valve 13B in order to equalize the pressure in the first adsorption tower 10A and the pressure in the second adsorption tower 10B. Then, the residual gas in the first adsorption tower 10A is supplied to the second adsorption tower 10B through the first pressure equalizing valve 13A and the second pressure equalizing valve 13B. Thereby, the pressure of the gas in the first adsorption tower 10A decreases, and the pressure of the gas in the second adsorption tower 10B increases.

The first pressure equalizing valve 13A and the second pressure equalizing valve 13B are opened until the gas pressure in the first adsorption tower 10A and the gas pressure in the second adsorption tower 10B become substantially the same.
The pressure of the gas in the first adsorption tower 10A is detected by a pressure sensor 15A provided near the outlet of the first adsorption tower 10A, and the pressure of the gas in the second adsorption tower 10B is the outlet of the second adsorption tower 10B. It is detected by a pressure sensor 15B provided in the vicinity. The detected pressure is output to the controller 30.

<First Depressurization Step-First Adsorption Tower: Decompression, Second Adsorption Tower: Holding>
In step S103, the controller 30 depressurizes the first adsorption tower 10A while holding the second adsorption tower 10B at the pressure after pressure equalization.
Specifically, the controller 30 opens the first decompression valve 14A. Then, the residual gas in the first adsorption tower 10A that has supplied the residual gas to the second adsorption tower 10B in step S102 is discharged to the combustion unit 23 via the first depressurization valve 14A, and the first adsorption tower 10A is desorbed. Pressed. Due to the residual gas thus discharged, impurities (such as carbon dioxide) adsorbed on the adsorbent of the first adsorption tower 10A are also discharged to the combustion unit 23, and as a result, the first adsorption tower 10A is washed. .
Such depressurization of the first adsorption tower 10A is continued for a predetermined time, and then the first depressurization valve 14A is closed.

  On the other hand, since the second depressurization valve 14B remains closed, the pressure in the second adsorption tower 10B is maintained at the pressure after pressure equalization in step S102. Therefore, after the depressurization of the first adsorption tower 10A, the pressure of the second adsorption tower 10B becomes higher than the pressure of the first adsorption tower 10A.

<Second pressure equalization step-first and second adsorption towers: pressure equalization>
In step S104, the controller 30 opens the first pressure equalizing valve 13A and the second pressure equalizing valve 13B in order to equalize the first adsorption tower 10A and the second adsorption tower 10B. Then, the residual gas in the second adsorption tower 10B is supplied to the first adsorption tower 10A through the second pressure equalizing valve 13B and the first pressure equalizing valve 13A. Thereby, the pressure of the second adsorption tower 10B decreases, and the pressure of the first adsorption tower 10A increases.
The first pressure equalizing valve 13A and the second pressure equalizing valve 13B are opened until the gas pressure in the first adsorption tower 10A and the gas pressure in the second adsorption tower 10B become substantially the same.

<Second Depressurization Step-First Adsorption Tower: Holding, Second Adsorption Tower: Decompression>
In step S105, the controller 30 depressurizes the second adsorption tower 10B while holding the first adsorption tower 10A at the pressure after pressure equalization.
Specifically, the controller 30 opens the second depressurization valve 14B. Then, the residual gas in the second adsorption tower 10B that has supplied the residual gas to the first adsorption tower 10A in step S104 is discharged to the combustion unit 23 via the second depressurization valve 14B, and the second adsorption tower 10B is desorbed. Pressed. Due to the residual gas thus exhausted, impurities (such as carbon dioxide) adsorbed on the adsorbent of the second adsorption tower 10B are also exhausted to the combustion unit 23, and as a result, the second adsorption tower 10B is washed. .
Such depressurization of the second adsorption tower 10B is continued for a predetermined time similarly to the depressurization of the first adsorption tower 10A in step S103, and then the second depressurization valve 14B is closed.

  On the other hand, since the first depressure valve 14A remains closed, the pressure in the first adsorption tower 10A is maintained at the pressure after pressure equalization in step S104. Therefore, after depressurization of the second adsorption tower 10B, the pressure of the first adsorption tower 10A becomes higher than the pressure of the second adsorption tower 10B.

In step S106, the controller 30 determines whether or not the pressure of the first adsorption tower 10A and the pressure of the second adsorption tower 10B are a predetermined pressure P0 (for example, substantially atmospheric pressure).
When it is determined that the pressure in the first adsorption tower 10A and the pressure in the second adsorption tower 10B are the predetermined pressure P0 (Yes in S106), the process of the controller 30 proceeds to step S107. On the other hand, when it is determined that the pressure in the first adsorption tower 10A and the pressure in the second adsorption tower 10B are not the predetermined pressure P0 (No in S106), the process of the controller 30 proceeds to step S108.

In step S107, the controller 30 controls all the valves (the first supply valve 11A, the second supply valve 11B, the first discharge valve 12A, the second discharge valve 12B, the first pressure equalizing valve 13A, the second pressure equalizing valve 13B, the first The pressure release valve 14A and the second pressure release valve 14B) are closed.
Thereafter, the process of the controller 30 proceeds to the end, and the stopping method of the hydrogen production apparatus 1 is terminated.

In step S108, the controller 30 determines whether or not the series of processes according to steps S102 to S105 has been repeated a predetermined number of times (for example, 2 to 5 times) or more. The predetermined number of times is related to the size of the first adsorption tower 10A and the second adsorption tower 10B, the type of gas, and the like, and is obtained by a preliminary test or the like.
If it is determined that the process has been repeated a predetermined number of times (Yes at S108), the process of the controller 30 proceeds to Step S107. On the other hand, when it determines with having not repeated more than predetermined times (S108 * No), the process of the controller 30 progresses to step S102.

≪Effects of hydrogen production equipment shutdown method≫
According to such a method for stopping the hydrogen production apparatus 1, the following effects can be obtained.
When an OFF signal (stop signal) is input from the switch 31 to the controller 30, the high-pressure gas of the first adsorption tower 10A being adsorbed is used to detect impurities in the first adsorption tower 10A and the second adsorption tower 10B. Impurities can be removed alternately. Thereby, the concentration of impurities contained in the produced hydrogen can be greatly reduced at the next startup (see FIG. 5). Therefore, it is not necessary to process hydrogen containing a large amount of impurities at the next start-up, and it is possible to shift to a steady state early after the next start-up.

  Further, by releasing the pressure after inputting the OFF signal, impurities that have not yet diffused can be easily removed in the first adsorption tower 10A and the second adsorption tower 10B. On the other hand, if the impurities are left in the first adsorption tower 10A and the second adsorption tower 10B for a long time, the impurities diffuse into the first adsorption tower 10A and the second adsorption tower 10B, and thus are difficult to remove. .

  Furthermore, when the OFF signal is generated, the gas remaining in the first adsorption tower 10A and the second adsorption tower 10B is not normally used as high-purity hydrogen thereafter, but as in the first embodiment, Impurities in the first adsorption tower 10A and the second adsorption tower 10B can be removed using the gas remaining in the first adsorption tower 10A and the second adsorption tower 10B.

Furthermore, since a series of processes according to step S102 to step S105 is repeated a predetermined number of times (No in S108), impurities that have not been removed by one depressurization are also reliably removed, and the first adsorption tower 10A. The second adsorption tower 10B can be suitably washed.
Further, the pressures of the first adsorption tower 10A and the second adsorption tower 10B become a predetermined pressure P0 that is an end determination criterion (S106 / Yes), and the gas flows between the first adsorption tower 10A and the second adsorption tower 10B. If it is determined that there is not, the depressurization and pressure equalization are terminated, so that it is possible to prevent the depressurization and pressure equalization from continuing unnecessarily after the OFF signal.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS. Only parts different from the first embodiment will be described.

  As shown in FIG. 6, the second embodiment includes step S203 instead of step S103 (see FIG. 3) according to the first embodiment, and step S205 instead of step S105 (see FIG. 3). .

In step S203, similarly to step S103, the controller 30 opens the first depressure valve 14A and opens the second discharge valve 12B and the first pressure equalizing valve 13A in order to depressurize the first adsorption tower 10A (see FIG. 7). ).
Then, the gas in the second adsorption tower 10B is supplied to the upper part of the first adsorption tower 10A via the second discharge valve 12B, the check valve 16, the orifice 17, and the first pressure equalizing valve 13A. The gas flowing from the second adsorption tower 10B to the first adsorption tower 10A is prevented from flowing back by the check valve 16, and is set to a small flow rate so that the pressure of the second adsorption tower 10B is not greatly reduced by the orifice 17. However, instead of the orifice 17, for example, a throttle valve or the like may be used.

Thus, when the gas of the second adsorption tower 10B is supplied to the upper part of the first adsorption tower 10A at a small flow rate, the gas supplied in this way pushes impurities of the first adsorption tower 10A to the outside ( Purge), impurities can be removed.
At this time, the second supply valve 11B may be opened to use the pressure of the gas remaining between the compressor 21 and the second supply valve 11B.
Then, after a predetermined time has elapsed, the controller 30 closes the second discharge valve 12B, the first pressure equalizing valve 13A, and the first pressure relief valve 14A.

In step S205, similarly to step S105, the controller 30 opens the second depressurization valve 14B and opens the first discharge valve 12A and the second pressure equalization valve 13B in order to depressurize the second adsorption tower 10B (see FIG. 7). ).
Then, the gas in the first adsorption tower 10A is supplied to the upper part of the second adsorption tower 10B via the first discharge valve 12A, the check valve 16, the orifice 17, and the second pressure equalizing valve 13B. The gas flowing from the first adsorption tower 10A to the second adsorption tower 10B is prevented from flowing back by the check valve 16, and is set to a small flow rate so that the pressure of the second adsorption tower 10B is not greatly reduced by the orifice 17.

Thus, when the gas of the first adsorption tower 10A is supplied to the upper part of the second adsorption tower 10B at a small flow rate, the gas supplied in this way pushes impurities of the second adsorption tower 10B to the outside ( Purge), impurities can be removed.
At this time, the first supply valve 11A may be opened to use the pressure of the gas remaining between the compressor 21 and the first supply valve 11A.
Then, after a predetermined time has elapsed, the controller 30 closes the first discharge valve 12A, the second pressure equalizing valve 13B, and the second depressurization valve 14B.

  As described above, in the second embodiment, the gas from the first adsorption tower 10A or the second adsorption tower 10B that has not been depressurized is supplied to the second adsorption tower 10B or the first adsorption tower 10A that has been depressurized at a small flow rate. The impurities supplied from the second adsorption tower 10B or the first adsorption tower 10A can be pushed out and removed by the gas supplied at this small flow rate.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be modified, for example, as follows without departing from the spirit of the present invention. May be combined as appropriate.

In the above-described embodiment, the case where there are two adsorption towers is illustrated, but the number of adsorption towers is not limited to this and may be three or more.
That is, for example, in a hydrogen production apparatus including a third adsorption tower in addition to the first adsorption tower 10A and the second adsorption tower 10B, impurities are adsorbed by the first adsorption tower 10A to purify hydrogen, and the second adsorption tower When the 10B and the third adsorption tower are depressurized, when an OFF signal is input, the residual gas of the first adsorption tower 10A is supplied to the second adsorption tower 10B and the third adsorption tower, After equalizing the pressure in the three adsorption towers (first pressure equalizing step), the first adsorption tower 10A is depressurized (first depressurizing step). Then, after supplying the residual gas of the second adsorption tower 10B and the third adsorption tower to the first adsorption tower 10A and equalizing the pressure of the first to third adsorption towers (second pressure equalization step), the second adsorption A method of depressurizing the tower 10B and the third adsorption tower may be used (second depressurization step).

Further, after depressurizing the first adsorption tower 10A (first depressurization step), the residual gas is supplied from the second adsorption tower 10B to the first adsorption tower 10A while maintaining the residual gas in the third adsorption tower as it is. Alternatively, after the first adsorption tower 10A and the second adsorption tower 10B are equalized (second equalization step), the second adsorption tower 10B may be depressurized (second depressurization step). And when depressurizing the 2nd adsorption tower 10B in this way, you may depressurize the 3rd adsorption tower.
Similarly, after depressurizing the first adsorption tower 10A (first depressurization step), the residual gas is supplied from the third adsorption tower to the first adsorption tower 10A while maintaining the residual gas in the second adsorption tower 10B. Alternatively, after the first adsorption tower 10A and the third adsorption tower are equalized (second equalization step), the third adsorption tower may be depressurized (second depressurization step). And when depressurizing the third adsorption tower in this way, the second adsorption tower 10B may also be depressurized.

In addition, the first adsorption tower 10A, the second adsorption tower 10B, and the third adsorption tower are provided, and each adsorption tower repeats adsorption of impurities (purification of hydrogen), depressurization (discharge of adsorbed impurities), and standby. In the hydrogen production apparatus, when the first adsorption tower 10A adsorbs impurities to purify hydrogen, the second adsorption tower 10B depressurizes, and the third adsorption tower is waiting, an OFF signal is input. When the residual gas of the first adsorption tower 10A is supplied only to the second adsorption tower 10B and the first adsorption tower 10A and the second adsorption tower 10B are equalized (first pressure equalization step), the first adsorption tower 10A is depressurized (first depressurization step), and then the residual gas is supplied from the second adsorption tower 10B to the third adsorption tower to equalize the pressure in the second adsorption tower 10B and the third adsorption tower (second Pressure equalization step), the second adsorption tower 10B is depressurized (second depressurization step). Thereafter, residual gas is supplied from the third adsorption tower to the first adsorption tower 10A to equalize the pressure in the first adsorption tower 10A and the third adsorption tower (third pressure equalization step), and then the third adsorption tower is depressurized. A method may be used (third decompression step).
That is, a method in which the residual gas of one adsorption tower is supplied to a part of the other adsorption tower, not all of the other adsorption towers, and the pressure is equalized and then depressurized, that is, the pressure equalizing step and the depressurizing step. Or may be repeated in order.

In the above-described embodiment, the case where the pressure of the first adsorption tower 10A is higher than the pressure of the second adsorption tower 10B when the OFF signal is input is illustrated. However, when the OFF signal is input, the first adsorption tower Decompression is performed at 10A, and adsorption is performed at the second adsorption tower 10B, and the pressure of the second adsorption tower 10B is higher than the pressure of the first adsorption tower 10A (when the pressure of the first adsorption tower 10A is low). The gas flow in steps S102 to S105 is reversed.
That is, in step S102, the residual gas in the second adsorption tower 10B is supplied to the first adsorption tower 10A to equalize the pressure, and then in step S103, the second depressurization valve 14B is opened to depressurize the second adsorption tower 10B. In step S104, the residual gas in the first adsorption tower 10A is supplied to the second adsorption tower 10B to equalize the pressure. Then, in step S105, the first depressure valve 14A is opened to depressurize the first adsorption tower 10A. .

  In the above-described embodiment, the case where the produced gas is hydrogen is exemplified, but the gas may be nitrogen, carbon dioxide, or the like. In this case, the type of adsorbent loaded in the adsorption tower and the gas flow direction in the adsorption tower are appropriately changed according to the type of gas.

It is a figure which shows the structure of the hydrogen production apparatus which concerns on 1st Embodiment. It is a time chart which shows the operation | movement at the normal time of the hydrogen production apparatus which concerns on 1st Embodiment. It is a flowchart which shows the operation | movement after receiving the OFF signal of the hydrogen production apparatus which concerns on 1st Embodiment. It is a time chart which shows the operation | movement after receiving the OFF signal of the hydrogen production apparatus which concerns on 1st Embodiment. It is a time chart which shows one effect of the hydrogen production apparatus concerning a 1st embodiment. It is a flowchart which shows the operation | movement after receiving the OFF signal of the hydrogen production apparatus which concerns on 2nd Embodiment. It is a time chart which shows the operation | movement after receiving the OFF signal of the hydrogen production apparatus which concerns on 2nd Embodiment.

Explanation of symbols

1 Hydrogen production equipment (gas production equipment)
10A 1st adsorption tower 10B 2nd adsorption tower 11A 1st supply valve 11B 2nd supply valve 12A 1st discharge valve 12B 2nd discharge valve 13A 1st pressure equalization valve 13B 2nd pressure equalization valve 14A 1st pressure release valve 14B 2nd pressure release valve 30 controller

Claims (5)

A method for stopping a gas production apparatus comprising two or more adsorption towers and producing gas by a PSA mechanism,
After the stop signal is input, a first pressure equalizing step of supplying the residual gas of at least one adsorption tower to the other adsorption towers so that the pressure between the adsorption towers is substantially the same;
A first depressurizing step for depressurizing the adsorption tower supplied with the residual gas in the first pressure equalizing step;
After the first depressurization step, a residual pressure in the adsorption tower that has not been depressurized is supplied to the depressurized adsorption tower, and a second pressure equalizing step in which the pressure between the adsorption towers is substantially the same;
A second depressurizing step for depressurizing the adsorption tower supplied with the residual gas in the second pressure equalizing step;
A method for stopping a gas manufacturing apparatus comprising: The two or more adsorption towers include a first adsorption tower and a second adsorption tower,
In the first pressure equalizing step, a pressure equalizing valve that connects the first adsorption tower and the second adsorption tower is opened, the residual gas of the first adsorption tower is supplied to the second adsorption tower, and the first The pressure in the adsorption tower and the second adsorption tower are substantially the same ,
In the first depressurization step, after closing the equalizing valve, to open the removal valve of the first adsorption tower, and depressurization of the first adsorption tower,
In the second pressure equalizing step, after closing the depressure valve of the first adsorption tower , the pressure equalizing valve is opened, and the residual gas of the second adsorption tower is supplied to the first adsorption tower, and the first adsorption The pressure of the tower and the second adsorption tower is substantially the same ,
In the second depressurization step, the after closing the equalizing valve, the second opening of de valve of the adsorption tower, the gas producing apparatus according to claim 1, characterized in that that push de the second adsorption tower How to stop. The method for stopping a gas production apparatus according to claim 2 , wherein when the stop signal is input, the pressure of the first adsorption tower is higher than the pressure of the second adsorption tower. In step pressure the adsorption tower de, wherein the portion of the residual gas in the adsorption tower which is not depressurized, to any one of claims 1 to 3, wherein the supply to the adsorption tower is depressurized Method for stopping gas production equipment. The method for stopping a gas production apparatus according to any one of claims 1 to 4 , wherein pressure equalization and depressurization are repeated in each adsorption tower until the pressure in each adsorption tower reaches a predetermined pressure. .

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