JP5939917B2 - Gas separation device - Google Patents

Description

  The present invention relates to a gas separation device.

  As background of this technical field, there are Patent Documents 1 and 2. Patent Document 1 describes that when high-purity nitrogen gas is separated, the time required for the nitrogen gas obtained after the start of operation to reach a predetermined purity is shortened.

JP 03-207420 A

  Patent Document 1 states that after the use of product nitrogen gas is stopped, the operation of the apparatus is continued within a range of 10 cycles or less, and then the apparatus is stopped, and the pipe between the adsorption tank and the nitrogen gas tank is closed at the start of operation. Thus, after the adsorption and regeneration operations are performed within a range of 20 cycles or less, the extraction of the product gas is started.

  In Patent Document 1, since the concentration of the product gas is not sufficiently high at the start of operation, it is necessary to perform at least a plurality of cycles of adsorption and regeneration operation, particularly when taking out high-purity nitrogen gas. Since a large number of cycles (empty operation of the adsorption tank) is required, it takes a long time to start extraction.

  An object of the present invention is to provide a gas separation device that can take out a high-purity product gas in a short time after the start of operation by performing a preliminary operation after the use of the product gas is stopped.

In order to solve the above problems, the present invention provides a compressor that compresses air, an adsorption tank that separates one gas from the compressed air supplied from the compressor and generates another gas as a product gas, and a storage tank in which the product gas generated by the suction tank, wherein a control unit for controlling the generation of a product gas in the adsorption vessel, after deactivation of the control unit the product gas, the reservoir tank before stopping use while discharging a product gas of low flow rate product gas than the flow rate that has been discharged to the outside to the outside from the storage tank from a feature in that the priming operation is supplied to the storage tank the product gas from the adsorption tank A gas separation device is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the gas separation apparatus which can take out product gas of high purity in a short time after an operation start can be provided.

It is a whole block diagram which shows the gas separation apparatus in Example 1 of this invention. It is a control flow figure of the gas separation device at the time of preliminary operation in Example 1 of the present invention. It is a control flow figure of the gas separation device at the time of preliminary operation in Example 1 of the present invention. It is an operation | movement flowchart of the gas separation apparatus at the time of the operation start in Example 1 of this invention. It is an operation | movement flowchart of the gas separation apparatus at the time of the operation start in a prior art example.

  A first embodiment of the present invention will be described with reference to FIG. The whole structure of the gas separation apparatus in a present Example is demonstrated using FIG.

  A gas separation device 1 shown in FIG. 1 is a PSA type gas separation device. The gas separation device 1 includes an air supply unit 2 that supplies air and a PSA unit 3 that generates product gas. The air supply unit includes a compressor 4 that compresses air, an air tank 5 that stores compressed air, an air dryer 6 that dehumidifies compressed air, and a drain filter 7 that removes impurities while collecting the drain water that has precipitated. have. In the present embodiment, as an example, the compressor 4, the air tank 5, the air dryer 6, and the drain filter 7 are stored in a casing. On the other hand, the PSA unit 3 separates a predetermined gas from the compressed air supplied from the air supply unit 2, thereby generating adsorption tanks 19 </ b> A and 19 </ b> B that generate product gas, and a nitrogen tank that stores product gas (nitrogen) ( Product gas storage tank) 41.

  The compressed air stored in the air tank 5 is supplied to adsorption tanks 19 </ b> A and 19 </ b> B described later, and a predetermined gas is separated from the compressed air stored in the air tank 5. In the present embodiment, the case where nitrogen is separated by adsorbing oxygen in the adsorption tanks 19A and 19B will be described. However, oxygen may be separated by adsorbing nitrogen, and other air may be separated from compressed air other than the atmosphere. The gas may be separated.

  As the compressor 4, a double-acting type, screw type or scroll type compressor, a booster compressor which is supplied with primary pressure from the outside and is recompressed, etc. are used, and only one of them is mounted. Alternatively, a plurality of units may be mounted.

  A pipe 16 through which compressed air from the air tank 5 flows is connected to the air tank 5, and pipes 17 </ b> A and 17 </ b> B branched into two systems are connected to the terminal position of the pipe 16. Supply pipes 18A and 18B for opening and closing the flow paths are provided in the middle of the pipes 17A and 17B, respectively, and adsorption tanks 19A and 19B for adsorbing oxygen molecules and taking out nitrogen gas as product gas are respectively connected. ing. This adsorption tank has a constant volume. The pipes 17A and 17B are connected to pipes 21A and 21B at positions between the supply valves 18A and 18B and the adsorption tanks 19A and 19B, respectively. Exhaust valves 22A, 22B are provided with an exhaust silencer 23 with a filter for silencing at the terminal. This exhaust silencer may be provided for each of the adsorption layers 19A and 19B. Further, pipes 25A and 25B are connected to the pipes 17A and 17B so as to connect the positions between the pipes 21A and 21B and the adsorption tanks 19A and 19B. The pipes 25A and 25B are opened and closed. Lower pressure equalizing valves 26A and 26B are provided.

  The adsorption tanks 19A and 19B are filled with, for example, an adsorbent that is an adsorbing means for adsorbing oxygen molecules. Specifically, molecular sieve carbon or zeolite is used as the adsorbent. Pipes 31A and 31B that merge with each other are connected to the adsorption tanks 19A and 19B, respectively. Pipes 32A and 32B are connected to the pipes 31A and 31B so as to connect the adsorption tanks 19A and 19B to each other, and a throttle 33 is provided in the pipes 32A and 32B. Pipes 35A and 35B are connected to the pipes 31A and 31B so as to connect the opposite sides of the adsorption tanks 19A and 19B to the pipes 32A and 32B. Upper pressure equalizing valves 36A and 36B that open and close are provided. The pipes 31A and 31B are provided with take-out valves 38A and 38B for opening and closing the flow paths on the opposite side of the adsorption tanks 19A and 19B from the pipes 35A and 35B, respectively. A pipe 40 is connected to a joining position of the pipes 31A and 31B, and a nitrogen tank 41 as a product gas storage tank for storing nitrogen gas is connected to the pipe 40. A pipe 43 provided with a discharge port 42 is connected to the nitrogen tank 41, and a filter that removes dust and the like and adjusts the gas pressure in order from the nitrogen tank 41 side in the middle of the pipe 43. A regulator 44, a discharge valve 45 for opening and closing the flow path, and a flow rate adjusting valve 46 for adjusting the flow rate of the product gas are provided. A pipe 48 and a pipe 49 are connected to the pipe 43 between the filter regulator 44 and the discharge valve 45. The pipe 48 has an opening / closing valve 50 for opening and closing the flow path in order from the pipe 43 side, A flow rate adjusting valve 51 for adjusting the flow rate and a silencer 52 are provided. The pipe 49 is provided with an open / close valve 54 that opens and closes the flow path, a flow rate adjustment valve 55 that adjusts the flow rate of gas, and an oxygen sensor 56 that detects the oxygen concentration in order from the pipe 43 side. The oxygen sensor 56 is communicably connected to the control unit 60 and outputs a detection signal to the control unit 60. The control unit 60 receives the detection signal and controls the generation of nitrogen gas in the adsorption tanks 19A and 19B.

  Specifically, the supply valves 18A and 18B, the exhaust valves 22A and 22B, the lower pressure equalizing valves 26A and 26B, the upper pressure equalizing valves 36A and 36B, the take-off valves 38A and 38B, the discharge valve 45, and the on-off valves 50 and 54 are controlled by the control unit. 60 is communicably connected, and operates in response to a command from the control unit 60.

  Up to now, the configuration of the gas separation device 1 has been described. Here, a gas separation method performed in the gas separation device will be described.

  In the gas separation device 1, the compression process of compressing air by the compressor 4, the storage process of storing the air compressed by the compression process in the air tank 5, the dehumidification process of dehumidifying the compressed air by the air dryer 6, and dehumidification by the dehumidification process A separation step for separating the gas from the air is performed.

  In the separation step of the gas separation device 1, the following steps (a) to (d) are sequentially repeated.

  (A) Adsorption / refluxing process: The compressed air compressed by the compressor 4 and stored in the air tank 5 is supplied to the adsorption tank 19 filled with the adsorbent by opening the supply valve 18, and the nitrogen tank 41. A step of recirculating the nitrogen gas remaining therein to the adsorption tank 19 by opening the take-off valve 38 to increase the pressure in the adsorption tank 19 and adsorbing oxygen molecules to the adsorbent using the pressure.

  (B) Extraction process: Continuing from the adsorption process, the compressed air is continuously supplied from the air tank 5 to the adsorption tank 19, and at the same time, the nitrogen gas separated and generated by the adsorbent is extracted from the adsorption tank 19 and stored in the nitrogen tank 41. Process.

  (C) Pressure equalization process: The pressure equalization of the pair of adsorption tanks 19 after completion of the take-out process is achieved by opening and closing the upper pressure equalization valve 36 and the lower pressure equalization valve 26, and the adsorption efficiency of the next adsorption process is increased to achieve higher purity For generating nitrogen gas.

  (D) Regeneration step: A step of regenerating the adsorbent by desorbing oxygen molecules adsorbed by the adsorbent through the pipe 21 by opening the exhaust valve 22 in the adsorption tank 19 after completion of the pressure equalization step. . In this regeneration process, the supply valve 18, the lower pressure equalizing valve 26, the upper pressure equalizing valve 36 and the take-off valve 38 related to the adsorption tank 19 other than the exhaust valve 22 are closed.

  While the adsorption process / removal process (process (a) (b)) is performed in the adsorption tank 19A, the regeneration process (process (d)) is performed in the adsorption tank 19B. Thereafter, the (c) pressure equalization step is performed simultaneously, and the adsorption tanks 19A and 19B are exchanged to perform the adsorption step / removal step (steps (a) and (b)) and the regeneration step (step (d)).

  The time of the above-described adsorption step (a), take-out step (b), and pressure equalization step (c) is taken as the cycle time.

  In this embodiment, as shown in FIG. 2, when a device stop signal is input to the controller 60 during operation of the device, the discharge valve 45 is closed, the on-off valve 50 is opened, and the flow rate adjusting valve 51 discharges nitrogen gas. The operation of the apparatus is continued by switching the flow rate (flow rate discharged from the discharge port 42) from the first set flow rate Q1 (for example, the flow rate when opening to the atmosphere) to the second set flow rate Q2. At this time, Q1> Q2. As means for switching from the first set flow rate Q1 to the second set flow rate Q2, it may be switched by changing the flow path by opening and closing the valve as in this embodiment, or may be switched by the flow rate adjusting valve 46. The operation while discharging the nitrogen gas of Q2 is a preliminary operation. This preliminary operation is continued until the nitrogen gas concentration D in the nitrogen tank 41 reaches a preset concentration D1, and when the nitrogen gas concentration D in the nitrogen tank 41 becomes D ≧ D1 Stop driving.

  When the apparatus operation signal is input to the control unit 60 before the nitrogen gas concentration D becomes D ≧ D1, the apparatus is operated by switching the nitrogen gas discharge flow rate from the second set flow rate Q2 to the first set flow rate Q1. continue.

  The conditions until the preliminary operation is stopped may be determined by the nitrogen gas concentration in the nitrogen tank 41 as shown in FIG. 2, or may be determined by the preset time as shown in FIG. Good.

  By operating the apparatus at a flow rate Q2 smaller than the flow rate Q1 when using nitrogen gas, the nitrogen gas with a slightly reduced purity in the nitrogen tank 41 is discharged little by little, and the high generated in the adsorption tanks 19A and 19B. Pure nitrogen gas can be stored in the nitrogen tank 41. Since the discharge flow rate is Q2, which is smaller than the flow rate Q1 when nitrogen gas is used, the purity of the nitrogen tank 41 can be increased in a short time without reducing the pressure of the nitrogen tank 41. By this preliminary operation, nitrogen gas having a purity higher than the nitrogen gas concentration when nitrogen gas is used can be stored in the nitrogen tank 41.

  Next, the operation of the gas separation device at the start of operation after the preliminary operation will be described with reference to FIG. In this embodiment, after the operation of the PSA unit 3 is started, the supply valve 18 and the take-off valve 38 are opened, and the air from the air supply unit 2 is supplied to either the adsorption tank 19A or 19B, and at the same time from the nitrogen tank 41 A high-purity nitrogen gas stored by operation is refluxed to the adsorption tank 19A or 19B by a specified amount. As a method for recirculating the specified amount, the recirculation amount may be controlled by the diameter of the extraction valve 38 or may be controlled by changing the time for opening the extraction valve by the control unit 90.

  After the adsorption, reflux process, and take-out process are completed, the upper pressure equalization valve 36 and the lower pressure equalization valve 26 are opened, and the pressure in the pair of adsorption tanks 19 is equalized. After the pressure equalizing step, the adsorption and reflux steps are switched again, and at the same time, discharge of nitrogen gas in the nitrogen tank 41 is started from the discharge port 42.

  Here, conventionally, since the preliminary operation in the present example was not performed, the concentration or pressure of the nitrogen tank 41 could not be ensured at the start of the operation. Therefore, as shown in FIG. 4B, when the operation is started, the take-off valve 36 between the nitrogen tank 41 and the adsorption tank 19 is closed at the start of operation, and the adsorption process is performed only with the supply air from the air supply unit 2. The nitrogen gas concentration or pressure in the nitrogen tank 41 was prevented from decreasing. On the other hand, in the present embodiment, the high-purity nitrogen gas in the nitrogen tank 41 stored in the preliminary operation is refluxed to the adsorption tank 19, thereby increasing the pressure and concentration of the nitrogen gas in the adsorption tank 19 at the start of operation. The adsorption efficiency of the adsorption tank 19 can be increased in a short time. As a result, it is possible to prevent a decrease in the concentration and pressure of nitrogen gas generated at the start of operation, and an adsorption step using only the supply air from the air supply unit 2 is not required. The energy consumption can be shortened.

  In this embodiment, the extraction of nitrogen gas is started after one adsorption, reflux process, and extraction process, but the extraction of nitrogen gas may be started after a plurality of processes.

  According to the present embodiment, by performing the preliminary operation, it is possible to prevent a decrease in the concentration and pressure of nitrogen gas in the nitrogen tank 41 at the start of operation, and the nitrogen gas in the nitrogen tank 41 is refluxed to the adsorption tank 19. A decrease in the concentration and pressure of nitrogen gas generated in the adsorption tank 19 at the start of operation can be prevented. Accordingly, it is possible to provide a gas separation device that can meet the needs of customers who want to use nitrogen gas immediately and can obtain an energy saving effect.

  The embodiments described so far are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention is not limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 1 ... PSA type gas separation apparatus 2 ... Air supply unit 3 ... PSA unit 4 ... Compressor 5 ... Air tank 6 ... Air dryer 7 ... Drain filter 19 ... Adsorption tank 41 ... Nitrogen layer 44 ... Filter regulator 52 ... Silencer 56 ... Oxygen sensor 60 ... Control unit

Claims (5)

A compressor for compressing air;
An adsorption tank that separates one gas from the compressed air supplied from the compressor and generates another gas as a product gas;
A storage tank for storing the product gas generated by the adsorption tank;
A control unit for controlling production of product gas in the adsorption tank,
After the use of the product gas is stopped, the control unit discharges the product gas from the storage tank to the outside while discharging a product gas having a lower flow rate than the product gas discharged from the storage tank to the outside before the use is stopped. A gas separation device that performs a preliminary operation of supplying the adsorption tank to the storage tank.   The gas separation device according to claim 1, wherein the control unit performs a preliminary operation until a product gas concentration in the storage tank reaches a specified value.   The gas separation device according to claim 1, wherein the control unit performs a preliminary operation for a specified time after the use of the product gas is stopped.   2. The gas separation device according to claim 1, wherein the control unit recirculates the product gas stored in the storage tank by the preliminary operation to the adsorption tank at the start of operation. Wherein the control unit, a gas separation apparatus according to claim 4, characterized in that to begin using the product gas after the product gas received in the storage tank is specified amount recirculated to the adsorption vessel by preliminary operation.

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