JP2018051447A - Operation method of gas separator, and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method of a gas separator, and a control device, capable of re-supplying product gas immediately, when supply of raw material gas is stopped owing to instantaneous voltage drop, a power failure or the like, and supply of the raw material gas is resumed thereafter.SOLUTION: When supply of raw material gas into a raw material gas tank 2 is stopped, delivery of product gas from a product tank 4 is stopped, and a timer for an adsorption step and a desorption step in adsorption towers 3A, 3B is stopped and held and operation is continued. When supply of the raw material gas is resumed, delivery of product gas from the product tank 4 is resumed, and operation of the adsorption step and the desorption step in the adsorption towers 3A, 3B is resumed from continuation of the stopped-and-held timer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an operation method and a control device in a gas separation device. More specifically, the gas separator is a mixture in which two or more kinds of gases such as air are mixed with two or more adsorption towers filled with an adsorbent such as molecular sieve carbon, activated carbon, zeolite, and the like. A gas source material is supplied to the adsorption tower under pressure to adsorb the easily adsorbed component gas, and the adsorbing process is performed by separating and extracting the hardly adsorbed component gas as a product gas. The desorption process for desorbing the easily adsorbed component gas to regenerate the adsorbent and the pressure equalization process for moving the gas in the adsorption tower after the adsorption process to the adsorption tower after the desorption process are performed with a predetermined timer. By alternately repeating each adsorption tower, a gas separation device (PSA (Pressure) that continuously obtains a product gas by utilizing the difference in adsorption speed between the easily adsorbed component gas and the hardly adsorbed component gas by the adsorbent. Even if the supply of the raw material gas is stopped due to an instantaneous voltage drop or a power failure, the operation of the gas separation device can be resumed immediately when the supply of the raw material gas is resumed. The present invention relates to a method for operating a gas separation device and a control device.

  In recent years, nitrogen gas separation devices have been widely used as means for supplying nitrogen gas in applications such as explosion-proof seals, metal processing, oxidation prevention, and product pressure feeding.

  By the way, the nitrogen gas separation apparatus pressurizes and feeds a source gas containing a large amount of nitrogen gas such as air and oxygen gas to an adsorption tower by means of a compressor, and mainly adsorbs nitrogen gas as product gas. It is designed to supply the product gas with the product gas specifications (gas purity, gas pressure, gas flow rate) required by the user (user) of the product gas. It takes a certain time to supply the product gas with the product gas specification.

  In such a nitrogen gas separator, the supply of the raw material gas is stopped when the compressor stops due to an instantaneous voltage drop or a power failure, etc., so that it becomes difficult to supply the product gas, and the supply of the raw material gas is resumed when the power failure is restored. However, since it takes a certain time to supply the product gas, it has been a problem to use a nitrogen gas separator.

  On the other hand, even if the supply of the source gas is stopped due to a power failure or an instantaneous drop, there is a conventional technique that can quickly resume the operation of the gas separation device when the supply of the source gas is resumed. For example, in the operation method of the prior art disclosed in Patent Document 1, when the supply of the raw material gas is stopped, the operation is continued until the pressure equalizing step is started, and the operation from the pressure equalizing step is continued until the supply of the raw material gas is resumed. When the supply of the raw material gas is resumed without shifting to the process, the pressure equalization process shifts to the next process.

Japanese Patent No. 5561815

  In the normal operation in which the supply of the raw material gas continues, the gas that has moved to the adsorption tower where the desorption process has been completed in the pressure equalization process has a high oxygen concentration near the raw material gas inlet of the adsorption tower, and oxygen near the product gas outlet. Since the gas concentration distribution is low, a gas having a low oxygen concentration is supplied to the product tank in the next adsorption step. However, in Patent Document 1, when the supply of the raw material gas is stopped and the duration time of the pressure equalization process is increased, the oxygen concentration distribution in the adsorption tower is leveled due to gas retention in the adsorption tower. For this reason, when the supply of the raw material gas is resumed and the pressure equalization process is shifted to the adsorption process, a gas near the product gas outlet of the adsorption tower having a higher oxygen concentration than normal operation is sent to the product tank, and the product gas There was a problem that the purity of nitrogen gas deteriorated.

  The present invention has been made in view of such conventional circumstances, and even when the supply time of the raw material gas is prolonged due to a power failure or the like, when the supply of the raw material gas is resumed due to a power failure recovery or the like, the product is immediately It is an object of the present invention to provide an operation method and a control device of a gas separation device that can re-supply gas.

  As a result of diligent research by the present inventors, during the period from the stop of the supply of the source gas to the source gas tank to the restart of the supply, the source gas accumulated in the source gas tank is used, and the timer of the adsorption process in the adsorption tower Of the gas separation device, which was impossible in the prior art, by eliminating the gas retention in the adsorption tower and making the gas concentration distribution in the adsorption tower close to that during normal operation. The operation method was found and the present invention was completed.

  Therefore, in order to solve the above problems, the present invention has the following method and apparatus.

  In the present invention, a raw material gas is supplied under pressure to two or more adsorption towers filled with an adsorbent, and each adsorption tower repeats an adsorption process, a pressure equalization process, a desorption process, and a pressure equalization process. An operation method of a gas separation apparatus that separates an easily adsorbed component gas and a hardly adsorbed component gas to produce a hardly adsorbed component gas as a product gas, and stores the product gas in a product tank, When the supply of the raw material gas to the raw material gas tank is stopped, the derivation of the product gas from the product tank is stopped, and the operation is continued with the adsorption process timer stopped, and the supply of the raw material gas to the raw material gas tank is stopped. When restarted, the operation of the gas separation device restarts the operation of the adsorption process from the continuation of the timer that has been stopped while restarting the derivation of the product gas from the product tank.

  In the above operation method, when the supply of the raw material gas is stopped during the pressure equalization process, the derivation of the product gas from the product tank is stopped, and the operation is continued until the adsorption process is started, and then the adsorption process timer is stopped and held. If the operation is continued and the supply of the raw material gas to the raw material gas tank is resumed, the derivation of the product gas from the product tank is resumed, and the operation of the adsorption process is resumed from the continuation of the stopped timer. Good.

  In this method, the product gas flows from the adsorption tower in the adsorption process to the adsorption tower in the desorption process by stopping and holding the timer in the adsorption process from the supply gas supply stop to the supply restart. Therefore, no gas stays in the adsorption tower. For this reason, the gas concentration distribution in the adsorption tower is close to the gas concentration distribution during normal operation in which the supply of the source gas to the source gas tank is continued. Therefore, when the supply of the raw material gas to the raw material gas tank is resumed, the product gas can be supplied again without deteriorating the product gas purity of the product gas.

  However, in the operation method according to the above method, the product gas purity of the product gas derived from the adsorption tower in which the adsorption process is continuously operated deteriorates when the supply gas supply stop time to the raw material gas tank becomes long. There is. In such a case, when the product gas whose product gas purity has deteriorated enters the product tank and the supply of the raw material gas to the raw material gas tank is resumed, the product gas purity of the product gas derived from the product tank deteriorates. Will be. Therefore, even if the supply gas supply stoppage time to the source gas tank becomes longer, the supply of the product gas can be performed again without deterioration of the product gas purity when the supply of the source gas to the source gas tank is resumed. I also found out how to drive.

  In the operation method, while the supply of the raw material gas to the raw material gas tank is stopped, the supply of the product gas from the adsorption tower that continues the adsorption process to the product tank may be stopped.

  In this method, the product gas derived from the adsorption tower that continues the adsorption process is not introduced into the product tank even if the supply gas supply stoppage time to the source gas tank becomes long. When the gas supply is resumed, the product gas can be supplied again without deteriorating the product gas purity.

  The operation method may be applied as an operation method of the nitrogen gas separation device when an instantaneous voltage drop or power failure occurs and supply of the raw material gas to the raw material gas tank is stopped.

  In the present invention, the raw material gas is supplied under pressure to two or more adsorption towers filled with an adsorbent, and each adsorption tower repeats an adsorption process, a pressure equalization process, a desorption process, and a pressure equalization process. A gas separation device that separates the easily adsorbed component gas and the hardly adsorbed component gas in the raw material gas to produce the hardly adsorbed component gas as a product gas and stores the product gas in a product tank, and is provided in the adsorption step in the adsorption tower. A control device that performs control for repeatedly performing the pressure equalization process, the desorption process, and the pressure equalization process, and when the supply of the source gas to the source gas tank is stopped during the adsorption process, the product gas is derived from the product tank. In addition to stopping the adsorption process timer and controlling to continue the operation, when the supply of the source gas to the source gas tank is resumed, the derivation of the product gas from the product tank is resumed and stopped. Timer that was held A control device for controlling to restart the operation of the adsorption step from more.

  In the control device, when the supply of the raw material gas is stopped during the pressure equalization process, the derivation of the product gas from the product tank is stopped and the operation is continued until the adsorption process is started, and then the adsorption process timer is stopped and held. When the supply of the raw material gas to the raw material gas tank resumes, the derivation of the product gas from the product tank is resumed and the operation of the adsorption process starts from the continuation of the stopped timer. It is good also as a control apparatus which performs control to resume.

  In the control device, while the supply of the raw material gas to the raw material gas tank is stopped, the control device performs control so as to stop the supply of the product gas from the adsorption tower that continues the adsorption process to the product tank. Good.

  In this control device, by closing the switching valve at the product outlet of the adsorption tower, the supply of the product gas having a low product gas purity from the adsorption tower to the product tank can be stopped, and the raw material gas to the raw gas tank can be stopped. When the supply is resumed, the product gas can be re-supplied without deteriorating the product gas purity of the product gas. Further, by providing a check valve in place of the switching valve at the product outlet of the adsorption tower, the supply of product gas from the adsorption tower to the product tank can be stopped.

  The control device may be applied as a control device that controls the operation of the nitrogen gas separator when an instantaneous voltage drop or power failure occurs and the supply of the raw material gas to the raw material gas tank is stopped.

  As described above, according to the operation method and the control device of the gas separation device of the present invention, even if the supply of the raw material gas to the raw material gas tank is stopped due to a power failure or the like, When the supply of is resumed, the product gas can be immediately resupplied without deteriorating the product gas purity of the product gas.

FIG. 1 is a system configuration diagram including a nitrogen gas separation device including a control device according to an embodiment of the present invention. FIG. 2 is a diagram showing the valve open / close state during normal operation and when a power failure occurs in a nitrogen gas separation apparatus equipped with a control device according to an embodiment of the present invention. FIG. 3 is a diagram showing valve open / closed states during normal operation and when a power failure occurs in a conventional nitrogen gas separation device.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram including a nitrogen gas separation device including a control device according to an embodiment of the present invention. As shown in FIG. 1, in this embodiment, the system includes a compressor 1 that pressurizes and supplies a source gas, a source gas tank 2 that accumulates source gas, and a nitrogen gas that separates and extracts a product gas from the source gas. It is constituted by a separation device 10. The raw material gas tank 2 is provided to supply the accumulated raw material gas to the nitrogen gas separation device 10, but the components (oil content, SOx, NOx, etc.) that cause deterioration of the adsorbent contained in the raw material gas are provided. It can be substituted by accumulating the raw material gas in the activated carbon tank to be pretreated.

  The nitrogen gas separation device 10 is an example of a gas separation device, and includes an adsorption tower (first adsorption tower) 3A, an adsorption tower (second adsorption tower) 3B, a product tank 4, valves CV1 to CV9, and a purge. A flow controller 5 and a control device 20 are provided, and each component is connected by piping. The valves CV1 to CV9 are open / close valves (for example, cylinder valves) that are independently controlled. The control device 20 provided in the nitrogen gas separation device 10 executes the operation method of the nitrogen gas separation device 10 by controlling the operation of the nitrogen gas separation device 10.

  Specifically, the valves CV1 and CV3 are inlet valves that open and close a raw material gas supply path L1, which is a piping path through which the raw material gas supplied to the adsorption tower 3A and the adsorption tower 3B passes, respectively. The source gas is a mixed gas containing nitrogen gas such as air and oxygen gas. The valves CV2 and CV4 are release valves that open and close a gas release path L2, which is a piping path through which the gas released from the adsorption tower 3A and the adsorption tower 3B passes, respectively. The valves CV5 and CV6 are outlet valves that open and close the product gas discharge path L3, which is a piping path through which the product gas taken out from the adsorption tower 3A and the adsorption tower 3B passes, respectively. A product tank 4 is provided in the product gas discharge path L3. The valves CV7 and CV8 are pressure equalizing valves that open and close a piping path through which a gas moving between the adsorption tower 3A and the adsorption tower 3B passes. The valve CV9 is a supply valve that opens and closes the product gas supply path L9 through which the product gas derived from the product tank 4 passes. One end of each of the inlet lines L1A and L1B is connected to the raw material gas inlet of the adsorption towers 3A and 3B, and the other end is connected to the raw material gas supply path L1 and the gas discharge path L2. One end of the outlet communication line L7, which is a piping path provided with the valve CV7, is connected to the product gas outlet of the adsorption tower 3A, and the other end is connected to the product gas outlet of the adsorption tower 3B. The inlet communication line L8, which is a piping path provided with the valve CV8, has one end connected to the inlet line L1A and the other end connected to the inlet line L1B. These valves CV <b> 1 to CV <b> 9 can be electrically controlled to be opened / closed by the control device 20 set as a timer.

  The purge flow rate regulator 5 is a regulator that regulates the flow rate of the product gas that passes through the purge gas line L5 and the outlet communication line L7 and is purged from the adsorption tower in the adsorption process to the adsorption tower in the desorption process. The purge flow rate controller 5 can adjust the flow rate of the product gas by a manual adjustment valve, an automatic adjustment valve, an orifice, or the like.

  The adsorption tower 3A and the adsorption tower 3B are each filled with molecular sieve carbon that adsorbs oxygen gas. Molecular sieve carbon is charcoal, coal, coke, coconut husk, resin, pitch, and other raw materials with many pores, carbonized at a high temperature and adjusted to a pore size of about 3-5 mm (angstrom), coal Adsorbents such as resin, resin, and pitch systems. Such molecular sieve carbon has the property of adsorbing oxygen gas more easily than nitrogen gas, and selectively adsorbs oxygen gas from a raw material gas that is a mixed gas containing nitrogen gas such as air and oxygen gas. Has the property of That is, in the adsorption towers 3A and 3B filled with molecular sieve carbon, oxygen gas in the raw material gas is an easily adsorbed component gas, and nitrogen gas is a hardly adsorbed component gas. In addition, molecular sieve carbon has an increased ability to adsorb oxygen gas under high pressure conditions. Therefore, molecular sieve carbon can adsorb a large amount of oxygen gas by pressurizing the inside of the adsorption tower, and then depressurize the inside of the adsorption tower while purging the product gas, which is a nitrogen gas of difficult adsorption component gas. Gas can be desorbed. Specific examples of such molecular sieve carbon include trade names GN-UC-H, GN-UC-S, 1.5GN-H, and 1.5GN-S manufactured by Kuraray Chemical Co., Ltd. In the nitrogen gas separation apparatus 10, adsorption and desorption of oxygen gas are alternately repeated by the adsorption tower 3A and the adsorption tower 3B, and the product gas is prepared by separating and concentrating the nitrogen gas from the raw material gas.

  With reference to FIG. 2 in addition to FIG. 1, the operation method at the time of normal operation of the nitrogen gas separator 10 and the operation method at the time of occurrence of a power failure will be specifically described. FIG. 2 is a diagram showing the valve open / close state during normal operation and when a power failure occurs in a nitrogen gas separation apparatus equipped with a control device according to an embodiment of the present invention.

  At the time of normal operation, the controller 20 performs the adsorption process, the pressure equalization process (first pressure equalization process), the desorption process, and the pressure equalization process (second pressure equalization process) as one cycle in each of the adsorption towers 3A and 3B. In order to repeat the process, the nitrogen gas is separated from the raw material gas as the product gas. Each of these processes is set with a timer, and the process is performed until the timer is up, and the process proceeds to the next process when the timer is up. In the present embodiment, the timer up time in the adsorption process and the desorption process is set to the same value, and the timer up time in the first pressure equalizing process and the second pressure equalizing process is set to the same value. At that time, while one of the adsorption towers is subjected to the adsorption process, the above-described valves are controlled by the control device 20 so that the other adsorption tower is subjected to the desorption process. The adsorption tower 3A and the adsorption tower 3B may be controlled by the same timer, but in the present embodiment, each is controlled by an individual timer.

  Specifically, as shown in FIG. 2, while the adsorption tower 3A is subjected to the adsorption process, the adsorption tower 3B is subjected to the desorption process (process (i)). Further, while the adsorption tower 3A is subjected to the first pressure equalization process, the adsorption tower 3B is subjected to the second pressure equalization process (process (ii)), while the adsorption tower 3A is subjected to the desorption process. The adsorption tower 3B is subjected to the adsorption step (step (iii)), and while the adsorption tower 3A is subjected to the second pressure equalization step, the adsorption tower 3B is subjected to the first pressure equalization step ((iv) Step)). Hereinafter, each process will be described in detail.

<Step (i)>
The process (i) is a process in which the adsorption tower 3A is subjected to the adsorption process and the adsorption tower 3B is subjected to the desorption process. Specifically, in step (i), the valve CV2, the valve CV3, and the valves CV6 to CV8 are closed and the valve CV1, the valves CV4, CV5, and the valve CV9 are opened by the control of the control device 20. Therefore, the raw material gas supplied to the nitrogen gas separation device 10 is supplied to the adsorption tower 3A. The raw material gas is compressed by the compressor 1 and supplied from the raw material gas tank 2 to the adsorption tower 3A under the pressure accumulated in the raw material gas tank 2. That is, the source gas is supplied to the adsorption tower 3 </ b> A through the source gas tank 2. In the adsorption tower 3 </ b> A, oxygen gas is adsorbed among the supplied raw material gases, and the separated nitrogen gas is sent to the product tank 4. In the adsorption tower 3A, since the oxygen gas is gradually adsorbed as the gas goes upward, the concentration distribution is such that the nitrogen gas concentration increases toward the product gas outlet side. The product gas having a predetermined nitrogen gas concentration is sent to the product tank 4 through the product gas discharge path L3, and is led out from the product tank 4 through the product gas supply path L9. The product tank 4 is a box having a primary storage space for appropriately storing the separated nitrogen gas as a product gas. On the other hand, the gas in the adsorption tower 3B is led out from the raw material gas inlet, released through the inlet line L1B and the gas discharge path L2 to the outside of the nitrogen gas separator 10 (usually in the atmosphere), and purged from the adsorption tower 3A during the adsorption process. The product gas produced desorbs the adsorbed oxygen gas and regenerates molecular sieve carbon.

<Step (ii)>
The process (ii) is a process in which the adsorption tower 3A is subjected to the first pressure equalization process and the adsorption tower 3B is subjected to the second pressure equalization process. Specifically, in the process (ii), the valves CV1 to CV6 are closed and the valves CV7 to CV9 are opened under the control of the control device 20. Therefore, the outlet communication line L7 in which the product gas outlet of the adsorption tower 3A and the product gas outlet of the adsorption tower 3B communicate via the valve CV7, the raw material gas inlet of the adsorption tower 3A, and the raw material gas inlet of the adsorption tower 3B are connected to the valve CV8. The gas in the adsorption tower 3A moves to the adsorption tower 3B through the inlet communication line L8 that communicates therewith.

  Therefore, a gas having a high nitrogen gas concentration in the adsorption tower 3A is introduced from the product gas outlet side of the adsorption tower 3B, and a gas having a low nitrogen gas concentration is adsorbed in the adsorption tower 3A. It is introduced from the raw material gas inlet side of the tower 3B. For this reason, also in the adsorption tower 3B, the tendency for the nitrogen gas concentration to become higher is maintained on the upper side. Therefore, in the next step (iii) (adsorption step in the adsorption tower 3B), the nitrogen gas concentration of the product gas discharged from the adsorption tower 3B can be increased.

  In the step (ii), not only the gas is moved from the adsorption tower 3A to the adsorption tower 3B, but also the product gas is moved from the product tank 4 to the adsorption tower 3B, or a part of the gas from the adsorption tower 3A is released into the atmosphere. However, the remaining gas may be moved to the adsorption tower 3B.

<Step (iii)>
The process (iii) is a process in which the adsorption tower 3A is subjected to a desorption process and the adsorption tower 3B is subjected to an adsorption process. Specifically, in the step (iii), the valve CV1, the valve CV4, the valve CV5, the valve CV7, and the valve CV8 are closed and the valve CV2, the valve CV3, the valve CV6, and the valve CV9 are opened by the control of the control device 20. Is done. Therefore, the raw material gas supplied to the nitrogen gas separation device 10 is supplied to the adsorption tower 3 </ b> B through the raw material gas tank 2. In the adsorption tower 3 </ b> B, oxygen gas is adsorbed among the supplied raw material gases, and the separated nitrogen gas is sent to the product tank 4. In the adsorption tower 3B, since the oxygen gas is gradually adsorbed as the gas moves upward, the concentration distribution is such that the nitrogen gas concentration increases toward the product gas outlet side. The product gas having a predetermined nitrogen gas concentration is sent to the product tank 4 through the product gas discharge path L3, and is led out from the product tank 4 through the product gas supply path L9. On the other hand, the gas in the adsorption tower 3A is led out from the raw material gas inlet, released through the inlet line L1A and the gas discharge path L2 to the outside (usually in the atmosphere) of the nitrogen gas separator 10, and purged from the adsorption tower 3B in the adsorption process. The product gas produced desorbs the adsorbed oxygen gas and regenerates molecular sieve carbon.

<Step (iv)>
The process (iv) is a process in which the adsorption tower 3A is subjected to the second pressure equalizing process, and the adsorption tower 3B is subjected to the first pressure equalizing process. Specifically, in the step (iv), the valves CV1 to CV6 are closed and the valves CV7 to CV9 are opened under the control of the control device 20. Therefore, the outlet communication line L7 in which the product gas outlet of the adsorption tower 3A and the product gas outlet of the adsorption tower 3B communicate via the valve CV7, the raw material gas inlet of the adsorption tower 3A, and the raw material gas inlet of the adsorption tower 3B are connected to the valve CV8. The gas in the adsorption tower 3B moves to the adsorption tower 3A through the inlet communication line L8 that communicates therewith.

  Therefore, a gas having a high nitrogen gas concentration in the adsorption tower 3B is introduced from the product gas outlet side of the adsorption tower 3A, and a gas having a low nitrogen gas concentration in the adsorption tower 3B is adsorbed. It is introduced from the raw material gas inlet side of the tower 3A. For this reason, the tendency for the nitrogen gas concentration to be higher in the upper side is maintained even in the adsorption tower 3A. Therefore, in the next step (i) (adsorption step in the adsorption tower 3A), the nitrogen gas concentration of the product gas discharged from the adsorption tower 3A can be increased.

  In the step (iv), not only the gas is moved from the adsorption tower 3B to the adsorption tower 3A, but also the product gas is moved from the product tank 4 to the adsorption tower 3A, or a part of the gas from the adsorption tower 3B is released into the atmosphere. However, the remaining gas may be moved to the adsorption tower 3A.

  When a power failure occurs in the process (i) during the normal operation and the supply of the raw material gas to the raw material gas tank 2 is stopped, a signal is transmitted to inform that the supply of the raw material gas to the raw material gas tank 2 is stopped. Then, it is inputted to the control device 20 from the outside, and the control device 20 determines that the supply of the raw material gas to the raw material gas tank 2 is stopped. When the control device 20 determines that the supply of the raw material gas to the raw material gas tank 2 is stopped, the CV 9 is closed under the control of the control device 20. At this time, CV1 to CV8 are held in the same valve open / closed state as in step (i) of normal operation. Therefore, the derivation of the product gas from the product tank 4 is stopped, the adsorption tower 3A continues the adsorption process, and the adsorption tower 3B continues the desorption process. At this time, in the control device 20, the adsorption process timer of the adsorption tower 3A and the desorption process timer of the adsorption tower 3B are stopped at the timing when the power failure occurs (timing when the supply of the raw material gas to the raw material gas tank 2 is stopped). Retained.

  When the power failure is restored and the supply of the raw material gas to the raw material gas tank 2 is resumed, a signal indicating that the supply of the raw material gas to the raw material gas tank 2 has been resumed is input to the control device 20 from the outside. 20 judges that the supply of the raw material gas to the raw material gas tank 2 has been resumed. When the control device 20 determines that the supply of the source gas to the source gas tank 2 has been resumed, the CV 9 is switched from the closed state to the open state under the control of the control device 20. At this time, CV1 to CV8 are held in the same valve open / closed state as in step (i) of normal operation. As a result, CV1 to CV9 are in the same valve open / closed state as in the step (i) of the normal operation from the continuation of the timer that has been stopped. Therefore, the derivation of the product gas from the product tank 4 is resumed, and the adsorption process of the adsorption tower 3A and the desorption process of the adsorption tower 3B are resumed from the continuation of the stopped timer.

  Further, when a power failure occurs in the process (i) during the normal operation, the control device 20 controls the CV 5 to be closed while the supply of the source gas to the source gas tank 2 is stopped. May be performed. Thereby, supply of the product gas from the adsorption tower 3A which is continuing the adsorption | suction process to the product tank 4 can be stopped.

  When a power failure occurs in the process (ii) during the normal operation and the supply of the raw material gas is stopped, a signal indicating that the supply of the raw material gas has been stopped is input to the control device 20 from the outside. 20 determines that the supply of the source gas has stopped. When the control device 20 determines that the supply of the raw material gas is stopped, the control device 20 controls the CV 9 to be closed, and the CV1 to CV8 continue until the timer (ii) in the normal operation is started, and then the normal operation is performed. The valve is switched to and held in the same valve open / closed state as in step (iii) of operation. In the control device 20, the desorption process timer of the adsorption tower 3A switched to the normal operation (iii) and the adsorption process timer of the adsorption tower 3B are switched to the normal operation (iii) (timer 0 second). The timing is stopped and held. Therefore, the derivation of the product gas from the product tank 4 is stopped, and after each of the adsorption towers 3A and 3B has passed the process (ii) of the normal operation, the adsorption tower 3A is switched to the desorption process and continues to operate. The tower 3B switches to the adsorption process and continues operation.

  The process (ii) can be performed in less than 10 seconds. Further, when a power failure occurs and the compressor 1 is stopped, it takes about 1 minute until the compressor 1 is restarted by the recovery from the power failure and the supply of the raw material gas to the raw material gas tank 2 is resumed. Therefore, when a power failure occurs in the process (ii) during the normal operation, the adsorption tower 3A is in the desorption process before the supply of the raw material gas to the raw material gas tank 2 is resumed after the power failure is recovered. The operation is continued by switching, and the adsorption tower 3B is switched to the adsorption process and continues the operation.

  When the power failure is restored and the supply of the raw material gas to the adsorption tower 3B via the raw material gas tank 2 is resumed, a signal indicating that the supply of the raw material gas to the raw material gas tank 2 has been resumed is sent from the outside to the control device 20. The control device 20 determines that the supply of the source gas to the source gas tank 2 has been resumed. When the control device 20 determines that the supply of the raw material gas has been resumed, the CV 9 is switched from the closed state to the open state under the control of the control device 20. At this time, CV1 to CV8 are held in the same valve open / closed state as in step (iii) of normal operation. Thus, CV1 to CV9 are in the same valve opening / closing state as in the process (iii) of the normal operation from the continuation of the timer that has been stopped. Therefore, the derivation of the product gas from the product tank 4 is resumed, and the desorption process of the adsorption tower 3A and the adsorption process of the adsorption tower 3B are resumed from the continuation of the stopped timer (from timer 0 seconds).

  When a power failure occurs in the process (iii) during the normal operation, the operation of the adsorption tower 3A and the adsorption tower 3B is switched when the power failure occurs in the process (i). Therefore, the description is omitted.

  In addition, when a power failure occurs in the process (iv) during the normal operation, the operation in which the steps of the adsorption tower 3A and the adsorption tower 3B are switched in the case of the power failure occurring in the process (ii). Since it is only doing, description is abbreviate | omitted.

  According to the operation method executed by the control of the control device 20 in the nitrogen gas separation device 10 of the present embodiment, even when the supply of the source gas due to a power failure or the like is stopped, The product gas can be immediately resupplied without deteriorating the nitrogen purity of the product gas.

  Examples will be specifically described below, but the present invention is not limited thereto.

  As common conditions for all examples and comparative examples, 1.5GN-H manufactured by Kuraray Chemical Co., Ltd. was used as the molecular sieve carbon packed in the adsorption tower. Using a nitrogen gas separator composed of two adsorption towers filled with 1 liter of molecular sieve carbon, using the air pressurized to 0.70 MPaG as the raw material gas, adsorption process, pressure equalization process, desorption in both adsorption towers The process and the pressure equalization process were repeated as one cycle, and nitrogen gas was separated as product gas. The one cycle time in both adsorption towers at that time was 126 seconds. The breakdown was 60 seconds for the adsorption process, 3 seconds for the pressure equalization process, 60 seconds for the desorption process, and 3 seconds for the pressure equalization process. The ultimate pressure of the adsorption tower in the adsorption process was 0.64 MPaG, and the product gas was constant at 5 L / min (designed nitrogen purity of product gas 99%). In addition, the supply of the raw material gas was stopped due to a power failure at the timing when the timer passed 20 seconds in the step (i) of the normal operation.

(Examples 1-3)
Using a system including a nitrogen gas separation device 10 constituted by two adsorption towers 3A and 3B as shown in FIG. 1, the controller 20 controls the opening and closing of the valves as shown in FIG. Examples 1 to 3 in Table 1 show the results of changing the time from when a power failure occurs and the supply of the raw material gas stops to when the supply of the raw material gas is resumed after the power failure is restored.

(Comparative Example 1)
FIG. 3 is a diagram showing valve open / closed states during normal operation and when a power failure occurs in a conventional nitrogen gas separation device. The piping configuration and the valve arrangement configuration are the same as those in FIG. 1 using a system including a nitrogen gas separation device composed of two adsorption towers 3A and 3B, and the control device provided in the conventional nitrogen gas separation device is used in FIG. Table 1 shows the results of controlling the opening and closing of the valve as shown in FIG. 1 to 100 seconds after the power failure occurred and the supply of the raw material gas was stopped until the power failure was restored and the supply of the raw material gas was resumed. This is shown in Comparative Example 1.

  As shown in Table 1, when Example 2 was compared with Comparative Example 1, in Example 2, a product gas having a design nitrogen gas purity of 99% could be supplied even after resuming the supply of the raw material gas. In Example 1, the nitrogen purity of the product gas supplied after resuming the supply of the raw material gas was 98.3%, and the designed nitrogen purity of 99% could not be secured.

  In addition, as shown in Table 1, in Examples 1 to 3, after the power failure occurred and the supply of the raw material gas was stopped, the time until the power failure was restored and the supply of the raw material gas was changed was changed. As a result, if the source gas was stopped for 120 seconds, a designed nitrogen purity of 99% could be secured.

  Even if the supply gas supply stoppage due to a power failure or the like becomes longer, the present invention can immediately supply the product gas without substantially deteriorating the product gas purity of the product gas when the supply of the raw material gas is resumed due to a power failure recovery or the like. It is the operating method and control apparatus of the gas separation apparatus which can be resupplied. Therefore, the nitrogen gas separation apparatus as an example using the present invention can be suitably used in technical fields such as explosion-proof seals, metal processing, oxidation prevention, and product pressure feeding.

DESCRIPTION OF SYMBOLS 10 Nitrogen gas separator 1 Compressor 2 Raw material gas tank 3A, 3B Adsorption tower 4 Product tank 5 Purge flow rate controller 20 Controller CV1-CV9 Valve L1 Raw material gas supply path L1A, L1B Inlet line L2 Gas discharge path L3 Product gas discharge Path L5 Purge gas line L7 Outlet communication line L8 Inlet communication line L9 Product gas supply path

Claims (8)

Easy adsorption in source gas by supplying raw material gas under pressure to two or more adsorption towers packed with adsorbent, and each adsorption tower repeats adsorption process, pressure equalization process, desorption process and pressure equalization process An operation method of a gas separation device for separating a component gas and a hardly adsorbed component gas to produce a hardly adsorbed component gas as a product gas, and storing the product gas in a product tank,
When the supply of the raw material gas to the raw material gas tank is stopped during the adsorption process, the derivation of the product gas from the product tank is stopped, and the operation is continued with the adsorption process timer stopped.
When the supply of the raw material gas to the raw material gas tank is resumed, the operation of the gas separation device resumes the operation of the adsorption process from the continuation of the stopped timer while resuming the derivation of the product gas from the product tank. If the supply of the raw material gas stops during the pressure equalization process, the product gas from the product tank is stopped and the operation is continued until the adsorption process is started, and then the adsorption process timer is stopped and the operation is continued. ,
The operation according to claim 1, wherein when the supply of the raw material gas to the raw material gas tank is resumed, the operation of the adsorption process is resumed from the continuation of the stopped timer while the derivation of the product gas from the product tank is resumed. Method.   The operating method according to claim 1 or 2, wherein the supply of the product gas from the adsorption tower that continues the adsorption process to the product tank is stopped while the supply of the raw material gas to the raw material gas tank is stopped.   The operation method according to any one of claims 1 to 3, which is an operation method of the nitrogen gas separation device when an instantaneous voltage drop or a power failure occurs and supply of the raw material gas to the raw material gas tank is stopped. Easy adsorption in source gas by supplying raw material gas under pressure to two or more adsorption towers packed with adsorbent, and each adsorption tower repeats adsorption process, pressure equalization process, desorption process and pressure equalization process The gas separation device that separates the component gas and the hardly adsorbed component gas to produce the hardly adsorbed component gas as the product gas and stores the product gas in the product tank is provided in the adsorption tower, and the adsorption process, pressure equalizing process, desorption in the adsorption tower A control device that performs control for repeatedly performing a process and a pressure equalizing process,
When the supply of the raw material gas to the raw material gas tank stops during the adsorption process, the product gas from the product tank is stopped, and the adsorption process timer is stopped and controlled to continue operation.
When the supply of the raw material gas to the raw material gas tank is resumed, the control device performs control so that the derivation of the product gas from the product tank is resumed and the operation of the adsorption process is resumed from the continuation of the stopped timer. If the supply of the raw material gas stops during the pressure equalization process, the product gas from the product tank is stopped and the operation is continued until the adsorption process is started, and then the adsorption process timer is stopped and the operation is continued. Control so that
6. When the supply of the raw material gas to the raw material gas tank is resumed, the control of restarting the operation of the adsorption process from the continuation of the stopped timer is resumed while the derivation of the product gas from the product tank is resumed. The control device described in 1.   The control is performed so as to stop the supply of the product gas from the adsorption tower that continues the adsorption process to the product tank while the supply of the raw material gas to the raw material gas tank is stopped. Control device.   8. The control device according to claim 5, which is a control device that controls operation in the nitrogen gas separation device when an instantaneous voltage drop or a power failure occurs and supply of the raw material gas to the raw material gas tank is stopped. The control device described.

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