JP2020033956A - Operation control method of compressor for gas generator and compressor for gas generator, as well as gas generator with compressor - Google Patents

Abstract

To provide a compressor capable of being applied to any of a gas generator in need of a high adsorption pressure and the gas generator in need of a low adsorption pressure.SOLUTION: A supply pressure (target pressure Pt) to a gas generator 20 can be selected between a low setting target pressure Ptl and a high setting target pressure Pth. A motor 12 of a compressor 10 is driven by a maximum rotation speed Nmax, when the low setting target pressure Ptl is set and a discharge side pressure Pd of a compressor body 11 is less than a low setting target pressure Ptl. The motor is driven by a rotational speed Ntl for maintaining the discharge side pressure Pd in the low setting target pressure Ptl, when being not less than the low setting target pressure Ptl. When the high setting target pressure Pth is set, the motor is driven by a maximum rotation speed Nmax at a discharge side pressure Pd being less than low setting target pressure Ptl, by a rated engine speed Nr at the pressure being not less than the low setting target pressure Ptl and being less than the high setting target pressure Pth, and by a rotational speed Nth for maintaining the discharge side pressure Pd to the high setting target pressure Pth at the pressure being not less than the high setting target pressure Pth.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas generator that generates a target gas by adsorbing and removing a specific component from a raw material gas by a pressure swing adsorption (PSA) method, and a raw material for the gas generator. The present invention relates to a gas generator configured by a compressor that supplies compressed gas, and more particularly, to an operation control method of a compressor used in the gas generator, a compressor that executes the operation control method, In addition, the present invention relates to the above-described gas generator including the compressor.

  The gas generator that produces gas by the pressure swing method described above uses an adsorbent that exhibits high adsorptivity to a specific gas contained in the pressurized source gas, and converts the specific gas from the source gas into a specific gas. The target gas is produced as a product gas by adsorbing and removing the gas.

  As an example, air is used as a raw material gas, and as a gas generator that produces components contained in this air as a product gas, the adsorbent that has high adsorptivity to oxygen is used to adsorb and remove oxygen in compressed air. "Nitrogen PSA device" to produce nitrogen gas, "Oxygen PSA device" to produce oxygen gas by adsorbing and removing nitrogen in compressed air by using an adsorbent that shows high adsorption to nitrogen, etc. is there.

  The gas generators described above use an adsorbent that exhibits high adsorptivity to the pressurized source gas to produce product gas. In addition to a gas generator serving as a main body of the above, a compressor for supplying a compressed gas as a raw material to the gas generator is a constituent element (see Patent Documents 1 and 2).

  However, the pressure (adsorption pressure) at which each adsorbent exhibits adsorbability to a specific gas differs depending on the type of adsorbent used. For example, a gas generator (oxygen PSA) has a relatively low adsorption pressure of 0.2 to 0.4 MPa, while a gas generator (nitrogen PSA) using MSC (Molecular Sieving Carbon), which exhibits adsorbability to oxygen, has a higher adsorption pressure. It requires an adsorption pressure of 0.5 to 1 MPa.

  Therefore, the compressor used in combination with these gas generators must be capable of supplying a compressed gas having a pressure corresponding to the adsorption pressure required by the gas generator that is the partner of the combination.

  Generally, in a compressor, a control called capacity control is performed in order to supply a stable and constant pressure of compressed gas to the consuming side even when the consumption of the compressed gas on the consuming side changes. As such capacity control, "speed control" that changes the operating speed of the compressor body according to the discharge pressure of the compressor body and "intake control" that controls the intake of the compressor body are performed. The pressure on the discharge side of the compressor body, that is, the pressure of the compressed gas supplied to the consumption side is controlled so as to approach a preset target pressure Pt.

  Therefore, the target pressure Pt set here is the pressure of the compressed gas supplied to the consuming side.

  Here, in the gas generator of the PSA system, the drive source of the compressor main body 11 is a motor (three-phase AC motor) 12 and the inverter 31 is used, as employed in the gas generators described in Patent Documents 1 and 2. The inverter-driven compressor 10 that controls the rotation speed of the compressor main body 11 by changing the frequency of the alternating current input to the motor 12 by using the compressor 12 is often used as a compressed air supply source.

  In such an inverter-driven compressor 10, as shown in FIG. 4, pressure detection means 33 for detecting the discharge side pressure Pd of the compressor body 11 is provided, and the discharge side of the compressor body 11 detected by the pressure detection means 33 is detected. The above-described “speed control” is performed by the feedback control in which the frequency of the alternating current output from the inverter 31 to the motor 12 is changed in accordance with the change in the pressure Pd to change the rotation speed of the motor 12, so that the consumer side Is controlled so that the pressure of the compressed gas supplied to the pressure approaches a preset target pressure Pt.

  Further, a suction valve 18 that opens and closes the suction passage 11a of the compressor body 11 is provided, and the opening and closing of the suction valve 18 is controlled in accordance with the discharge side pressure Pd of the compressor body 11, thereby achieving the aforementioned "suction control". "I do.

  As an example, the pressure of the compressed gas to be supplied to the consuming side (gas generator) is set as the target pressure Pt, and the unload start pressure Pu, which is a predetermined high pressure relative to the target pressure Pt, is set. Then, the pressure of the compressed gas actually supplied to the consuming side (gas generator), that is, the discharge side pressure Pd of the compressor main body 11 detected by the pressure detecting means 33 is made equal to the target pressure Pt described above. If the discharge side pressure Pd detected by the detection means 33 is equal to or higher than the target pressure Pt, the frequency of the alternating current output to the motor 12 is decreased as the discharge side pressure Pd increases to shift the motor 12 to low speed operation, When the discharge-side pressure Pd of the machine body 11 falls below the target pressure Pt, the frequency of the alternating current output to the motor 12 increases, and when the discharge-side pressure Pd continues below the target pressure Pt, the motor 12 is stopped. Operation control shifts to high speed operation of rotating at a maximum speed Nmax has been made of.

  When the discharge side pressure Pd of the compressor main body 11 detected by the pressure detecting means 33 becomes equal to or higher than the above-described unload start pressure Pu, the suction valve 18 is operated to close the suction flow passage 11a of the compressor main body 11. When the operation shifts to the no-load operation and the pressure detecting means 33 detects that the discharge side pressure Pd has dropped below the target pressure Pt, the suction valve 18 is opened and the compressor body 11 sucks air to perform compression. Shift to load operation.

JP-A-6-31129 JP 2002-45635 A

  In the inverter-driven compressor 10 configured as described above, since the compressor body 11 acts as a load on the motor 12, the target pressure Pt, which is the pressure setting of the compressed gas supplied to the consuming side, is reduced. When the back pressure of the compressor main body 11 is reduced in this way, the power required to drive the compressor main body 11 also decreases, so that the load on the motor 12 decreases.

  Therefore, a compressor used in a gas generator (nitrogen PSA) requiring an adsorption pressure of 0.5 to 1 MPa is replaced with a gas generator (oxygen gas) requiring an adsorption pressure of 0.2 to 0.4 MPa. If the pressure is to be diverted to a compressor that supplies compressed air to the PSA), the above-described target pressure Pt is reduced and the discharge side pressure Pd of the compressor body 11 is reduced. There is a margin in the output of the motor.

  However, a general inverter-driven compressor has a maximum rotational speed Nmax of the motor (therefore, the maximum frequency fmax of the alternating current that causes the motor to generate this rotational speed) even if the target pressure Pt is reduced. Since this is fixed at a fixed value without changing it, even if the output of the motor 12 has a margin by lowering the setting of the target pressure Pt, the motor 12 is operated while maintaining the margin. Since the capacity of the motor 12 cannot be sufficiently exerted, efficient generation of compressed air and, therefore, efficient production of product gas cannot be performed.

  In order to solve such a problem and to be able to operate the motor 12 in a state where the performance of the motor 12 is maximized, the maximum rotation speed Nmax of the motor 12 is made variable and supplied to the gas generator. When the pressure of the compressed gas (target pressure Pt) is decreased, the maximum rotation speed Nmax of the motor is set higher by the margin generated in the output due to the decrease in the target pressure Pt, and the compressed gas supplied to the gas generator is set. It is conceivable that the production efficiency of the product gas is improved by increasing the amount of the gas.

  However, the inventors of the present invention attempted to lower the discharge pressure to 0.6 MPa by changing the setting of the target pressure Pt of the inverter-driven compressor having a shaft power of 37 kW and a discharge pressure of 0.7 MPa. An attempt was made to increase the discharge air volume by increasing the rotation speed of the motor by the margin of the output caused by the decrease in the target pressure so that the output was constant at 37 kW. The increment of the compressed gas was less than half of the theoretical value, and in the case of diversion of the compressor as described above, the compressor could not be operated efficiently after all.

  Specifically, when the above-described compressor with a shaft power of 37 kW is reduced from 0.7 MPa to 0.6 MPa at the discharge side pressure without changing the maximum rotational speed Nmax, the shaft power (theoretical value) is 33. In this compressor, the shaft power (theoretical value) of 3.2 kW (approximately 9%) is reduced due to the decrease in the discharge side pressure described above. Therefore, in theory, this amount can be used for increasing the rotation speed and, accordingly, increasing the amount of compressed air.

  However, when the rotation speed was increased so that the output of the motor became 37 kW with the discharge pressure reduced from 0.7 MPa to 0.6 MPa by experiments, the compressed air obtained by this increase in rotation speed was obtained. The increase in the amount was only about 4%, which was less than half the theoretical value (about 9%), indicating that the compressor could not be operated efficiently.

  Although the oxygen PSA device and the nitrogen PSA device differ only in the type of adsorbent contained in the adsorption tower and have the same gas generator structure, the oxygen PSA device and the nitrogen PSA device have the highest efficiency, respectively. If it is intended to operate the compressors, it is necessary to design the inverter-driven compressor used as a supply source of the compressed air for the oxygen PSA device and the nitrogen PSA device respectively.

  As described above, if the inverter-driven compressor is exclusively designed for each type of gas generator, the benefits such as cost reduction due to common use of the compressor used cannot be obtained.

  Also, if the compressors can be shared without having to be designed exclusively, the same gas generator can be used and the adsorbent can be changed, which can be used as an oxygen PSA device or a nitrogen PSA device. It can be used in a typical way.

  Therefore, the present invention can be applied to both a gas generator requiring a relatively high adsorption pressure by a common compressor and a gas generator requiring a relatively low adsorption pressure. Provided is an operation control method for a gas generator compressor capable of efficiently generating a compressed gas regardless of the application, and a gas generator compressor for executing the control method. Accordingly, an object of the present invention is to provide a gas generator that can be diverted to the production of multiple types of product gases.

  Hereinafter, means for solving the problems will be described together with reference numerals used in embodiments for carrying out the invention. This reference numeral is used to clarify the correspondence between the description of the claims and the description of the embodiment for carrying out the invention, and, needless to say, is limitedly used for interpreting the technical scope of the invention. It is not something that can be done.

In order to achieve the above object, a method for controlling the operation of the gas generator compressor 10 of the present invention comprises:
A compressor body 11 that is used as a source gas source for a pressure swing adsorption type gas generator 20 and generates compressed gas, a motor 12 that drives the compressor body 11, and an AC current that is input to the motor 12 Of the motor 12 by changing the frequency of the alternating current output by the inverter 31 in accordance with a change in the discharge side pressure Pd of the compressor body 11. Speed control is performed to change the discharge side pressure Pd of the compressor body 11 closer to a preset target pressure Pt by changing between a maximum rotation speed Nmax which is an upper limit of the control range and an unload rotation speed Nmin which is a lower limit. In the compressor 10 for a gas generator,
The target pressure Pt can be selectively set to a predetermined low set target pressure Ptl and a high set target pressure Pth higher than the low set target pressure Ptl,
Correspondence relationship between a change in the discharge side pressure Pd of the compressor body 11 and a change in a rated rotation speed Nr, which is a rotation speed at which the motor 12 generates a rated output,
Correspondence between a change in the discharge side pressure Pd of the compressor main body 11 and a change in a low set target rotation speed Ntl, which is a rotation speed at which the discharge side pressure Pd matches the low set target pressure Ptl,
With respect to a change in the discharge side pressure Pd of the compressor main body 11, a correspondence relationship between a change in a high set target rotation speed Nth, which is a rotation speed that matches the discharge side pressure Pd with the high set target pressure Pth, is obtained.
When the low set target pressure Ptl is set and the discharge side pressure Pd of the compressor body 11 is lower than the low set target pressure Ptl, the maximum rotational speed Nmax and the low set target pressure Ptl or more are set. , The low set target rotation speed Ntl,
When the high set target pressure Pth is set and the discharge side pressure Pd of the compressor main body 11 is lower than the low set target pressure Ptl, the maximum rotational speed Nmax and the low set target pressure Ptl or more are set. And when the pressure is lower than the high set target pressure Pth, the rated rotation speed Nr, and when the pressure is equal to or higher than the high set target pressure Pth, the high set target rotation speed Nth,
, And drives the motor 12.

A suction valve 18 for opening and closing a suction passage 11a of the compressor body 11;
A low pressure set unload start pressure Pul, which is a predetermined high pressure with respect to the low set target pressure Ptl, and a high pressure set unload start pressure Puh, which is a predetermined high pressure with respect to the high set target pressure Pth, respectively;
At the time of setting the low set target pressure Ptl, when the discharge side pressure Pd of the compressor body 11 becomes equal to or higher than the low pressure set unload start pressure Pul during driving of the motor 12 at the low set target rotation speed Ntl. When the high set target pressure Pth is set, the discharge side pressure Pd of the compressor body 11 becomes higher than the high pressure set unload start pressure Puh during driving of the motor 12 at the high set target rotation speed Nth. At this time, the intake valve 18 is closed to stop the intake of the compressor body 11 (claim 2).

  The components of the compressor such as a receiver tank 13, an oil separator 13a, an aftercooler 17, and a dryer 19 (see FIG. 4) provided on the discharge side of the compressor main body 11 (see FIG. 4). Preferably has a processing capacity corresponding to the amount of compressed gas to be discharged (claim 3).

  The component device may be a dehumidifier that dehumidifies the compressed gas generated in the compressor body 11, and determines the dehumidifying capacity of the dehumidifier by the compressed gas discharged from the compressor body at the maximum rotation speed Nmax. Corresponding to the amount (claim 4).

Further, the compressor 10 for a gas generator of the present invention
A compressor body 11 that is used as a source gas source for a pressure swing adsorption type gas generator 20 and generates compressed gas, a motor 12 that drives the compressor body 11, and an AC current that is input to the motor 12 And an inverter 31 for changing the frequency of the AC current output from the inverter 31 in accordance with a change in the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33. The rotation speed of the compressor is changed between the maximum rotation speed Nmax which is the upper limit of the rotation speed control range and the unload rotation speed Nmin which is the lower limit, and the discharge side pressure Pd of the compressor body is set to a predetermined target pressure Pt. In the compressor 10 for a gas generator provided with a control device 50 that performs a speed control approaching the pressure,
In the control device 50,
A target pressure setting unit 51 that can selectively set a predetermined low set target pressure Ptl and a high set target pressure Pth higher than the low set target pressure Ptl as the target pressure Pt;
Correspondence relationship between a change in the discharge side pressure Pd of the compressor body 11 and a change in a rated rotation speed Nr which is a rotation speed at which the motor 12 generates a rated output;
Correspondence of the change of the discharge side pressure Pd of the compressor body 11 to the change of the low set target rotation speed Ntl, which is the rotation speed that matches the discharge side pressure Pd with the low set target pressure Ptl, and
The correspondence relationship between the change in the discharge side pressure Pd of the compressor body 11 and the change in the high set target rotation speed Nth, which is the rotation speed at which the discharge side pressure Pd matches the high set target pressure Pth, is stored. A storage unit 55;
When the low set target pressure Ptl is set and the discharge side pressure Pd of the compressor body 11 is lower than the low set target pressure Ptl, the maximum rotational speed Nmax and the low set target pressure Ptl or more are set. , The low target rotation speed Ntl,
When the high set target pressure Pth is set and the discharge side pressure Pd of the compressor body 11 is lower than the low set target pressure Ptl, the maximum rotation speed Nmax and the low set target pressure Ptl or more are set. And when the pressure is lower than the high set target pressure Pth, the rated rotation speed Nr, and when the pressure is equal to or higher than the high set target pressure Pth, the high set target rotation speed Nth,
And a frequency control signal output unit 53 for outputting a frequency control signal for outputting an alternating current having a frequency corresponding to the inverter 31 to the inverter 31.

In the compressor 10 having the above configuration, a suction valve 18 for opening and closing the suction passage 11a of the compressor main body 11 is provided, and an electromagnetic valve 34 for controlling the introduction and discharge of the operating pressure of the suction valve 18 to the pressure receiving chamber. And an electromagnetic valve control signal output unit 54 for outputting a control signal for controlling the opening and closing of the electromagnetic valve 34 is provided in the control device 50.
The storage unit 55 of the control device 50 stores a low-pressure set unload start pressure Pul, which is a predetermined high pressure with respect to the low set target pressure Ptl, and a high-pressure set, which is a predetermined high pressure with respect to the high set target pressure Pth. Unloading start pressure Puh is memorized,
When the low set target pressure Ptl is set, the frequency control signal output unit 53 detects the discharge side of the compressor body 11 detected by the pressure detection unit 33 while the motor 12 is driving at the low set target rotation speed Ntl. When the pressure Pd is equal to or higher than the low-pressure set unload start pressure Pul, the frequency control signal output unit 53 drives the motor 12 at the high-set target rotation speed Nth when the high-set target pressure Pth is set. When the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33 becomes equal to or higher than the high pressure set unload start pressure Puh, the solenoid valve control signal output unit 54 On the other hand, a control signal for operating the suction valve 18 to close the suction valve 18 may be output (claim 6).

  Further, the components of the compressor 10 provided on the discharge side of the compressor main body 11 have a processing capacity corresponding to the amount of compressed gas discharged from the compressor main body 11 at the maximum rotation speed Nmax. Is preferable (claim 7).

  In this case, the component device may be a dehumidifier for dehumidifying the compressed gas generated in the compressor body 11, and the compressor body 11 discharges the dehumidifying capacity of the dehumidifier at the maximum rotation speed Nmax. It may be adapted to correspond to the amount of compressed gas (claim 8).

  Further, the gas generator 1 according to the present invention is a pressure swing adsorption type in which any one of the above-described gas generator compressors 10 and a supply of compressed gas from the gas generator compressor 10 to produce a product gas. (Claim 9).

  With the configuration of the present invention described above, in the gas generator 1 including the compressor 10 that executes the control method of the present invention, the target pressure Pt is set to either the low set target pressure Ptl or the high set target pressure Pth. However, the generation of the compressed gas and the production of the product gas could be performed efficiently without causing an unnecessarily large margin in the output of the motor 12.

  In particular, the components provided on the discharge side of the compressor body 11 have a processing capacity corresponding to the amount of compressed gas generated by the compressor body 11 when the motor 12 is rotating at the maximum rotation speed Nmax. Accordingly, the maximum amount of the compressed gas generated by the compressor body 11 can be introduced into the gas generator 20 without delay, and the pressure loss generated in the compressed gas before reaching the gas generator 20 can be minimized. Was completed.

  With this configuration, the processing capacity of these devices is larger than the amount of compressed gas generated by the compressor main body 11 at the time of high pressure setting where the amount of compressed gas discharged from the compressor main body 11 is smaller than at the time of low pressure setting. This improves performance and reduces pressure loss at high pressure settings compared to using a compressor designed for high pressure settings. An amount of compressed gas close to the theoretical value at the time of setting each target pressure could be supplied to the gas generator 20 without causing any loss.

FIG. 1 is an explanatory diagram of a gas generator according to the present invention. FIG. 3 is a functional block diagram of a control device. Operation | movement explanatory drawing of the compressor for gas generators of this invention. Explanatory drawing of an inverter drive compressor.

  Hereinafter, the gas generator of the present invention will be described with reference to the accompanying drawings.

  In the following description, the same components as those described as the related art will be described using the same reference numerals.

  In the following description, the gas generator of the present invention is configured as an oxygen PSA device for producing oxygen gas from compressed air at a low pressure setting, and as a nitrogen PSA device for producing nitrogen gas from compressed air at a high pressure setting. Although described by way of example, the gas generator of the present invention is not limited to use as an oxygen PSA device and a nitrogen PSA device, and various known gases can be used by changing the adsorbent to be used or changing the raw material gas. It can be configured as a generator.

[Overall configuration of gas generator]
Reference numeral 1 in FIG. 1 denotes a gas generator of the present invention, and this gas generator 1 produces a target product gas by separating predetermined components contained in compressed air by adsorption with an adsorbent. The gas generator 20 includes a compressor 10 for supplying compressed air as a raw material of a product gas to the gas generator 20.

[Gas generator]
The gas generator 20, which is one of the main components of the gas generator 1 of the present invention, uses compressed air supplied from a compressor 10 described later as a raw material, separates components in the compressed air, To produce product gas.

  In the present embodiment in which an oil-cooled screw compressor described later is employed as the compressor body 11 of the compressor 10, an activated carbon tower 22 is provided in the gas generator 20, and the compressed air introduced into the gas generator 20 is discharged from the gas generator 20. First, the oil and organic matter contained in the compressed air can be adsorbed and removed by being introduced into the activated carbon tower 22.

  The gas generator 20 mounted on the gas generator 1 of the present invention is a device that removes nitrogen or oxygen from compressed air by a pressure swing adsorption method (PSA method) to produce a product gas, and is housed in an adsorption tower described later. Depending on the type of adsorbent to be used, it can be configured as either an oxygen PSA device or a nitrogen PSA device.

  As an example, an oxygen PSA device for producing oxygen gas as a product gas is configured by storing zeolite exhibiting an adsorption property for nitrogen in the adsorption towers T1 and T2 of the gas generator 20. A nitrogen PSA device for producing nitrogen gas as a product gas by housing the indicated MSC (Molecular Sieving Carbon) in the adsorption towers T1 and T2 is configured.

  The gas generator 20 includes a plurality of adsorption towers (T1, T2) filled with an adsorbent, and repeatedly pressurizes and depressurizes (pressure swings) the adsorption towers T1 and T2 alternately in tens of seconds. Thus, when the adsorbent is being regenerated in one adsorption tower (for example, T2), the target gas is produced using the other adsorption tower (for example, T1), so that the product gas is continuously produced. It is configured so that it can be manufactured.

  In order to enable adsorption and regeneration by such a pressure swing, the gas generator 20 is provided with an air circuit that connects the above-mentioned adsorption towers T1 and T2 in parallel, and the solenoid valves SV1 to SV8 provided in the air circuit are provided. A reflux / adsorption process in which compressed air is recirculated to each of the adsorption towers T1 and T2 to adsorb predetermined components to the adsorbent in the adsorption towers T1 and T2 by controlling the opening and closing according to a predetermined sequence, and the predetermined components are adsorbed. An extraction step of removing the product gas generated by the removal from the adsorption towers T1 and T2, an equalization step of stopping the introduction of compressed air from the compressor 10 and communicating the two adsorption towers T1 and T2 to equalize the pressure; A regenerating step of regenerating the adsorbent by releasing the gas adsorbed by the adsorbent as an exhaust gas by opening the adsorption towers T1 and T2 to the atmosphere through the vent port 21; Compressed air The pressure equalization step of the two adsorption columns T1, T2 to communicate with pressure equalization stops the introduction is configured to carry out alternately in each of the adsorption columns T1, T2.

  In this way, the product gas generated in the adsorption towers T1 and T2 is configured to be supplied to the buffer tank 23 through the product gas outlet 24 after the pulsation is removed therefrom. I have.

  On the other hand, the gas adsorbed by the adsorbent filled in the adsorption towers T1 and T2 is discharged through the vent 21 provided with a silencer during the above-mentioned regeneration step in which the adsorption towers T1 and T2 are opened to the atmosphere. Released as gas.

(Compressor)
The compressor 10 for supplying compressed air to the gas generator 20 includes a compressor main body 11 and a motor 12 for driving the compressor main body 11, as shown in FIG.

  In the present embodiment, the compressor body 11 is an oil-cooled screw compressor that compresses the sucked air together with the lubricating oil injected into the cylinder and discharges the compressed air. A receiver tank 13 for introducing compressed gas discharged from the machine main body 11 together with the lubricating oil is connected to the receiver tank 13. By introducing compressed air discharged as a gas-liquid mixed fluid with the lubricating oil into the receiver tank 13, the compressed air is compressed. It is configured so that it can be separated into air and lubricating oil.

  The compressed air from which the lubricating oil has been separated in the receiver tank 13 is cooled, if necessary, after the oil remaining in the mist state in the compressed gas is removed by an oil separator 13a provided in the receiver tank 13. After-cooler 17 that removes moisture in the compressed air by removing the compressed air after passing through the after-cooler 17 to further remove the moisture in the compressed air, and heat-dry the compressed air from which the moisture has been removed to dehumidify. The lubricating oil supplied to the gas generator 20 described later from the supply flow path 14 via the dryer 19 (see FIG. 4) and collected in the receiver tank 13 passes through the oil cooler 15 and the oil filter (not shown). After passing through, the oil is supplied to the oil supply port of the compressor body 11 again through the oil supply passage 16.

  Equipment that constitutes the compressor 10 such as the above-described receiver tank 13, oil separator 13a, aftercooler 17, and dryer 19 provided in the flow path of compressed air from the discharge port of the compressor body 11 to the gas generator (FIG. 4). Is designed so as to exhibit sufficient oil separation capacity and dehumidification capacity with respect to the amount of compressed gas discharged from the compressor body 11 when the motor 12 is rotated at the maximum rotation speed Nmax described later. Have been.

  In the present invention, the aftercooler 17 and the dryer 19, which are devices that cool the compressed air and remove moisture in the compressed air, of the devices that constitute the compressor 10, are dehumidifiers that dehumidify the compressed air.

  An inverter 31 is provided between the motor 12 and the power supply for converting the frequency of an alternating current from the power supply and outputting the converted frequency to the motor 12. Is controlled so that the rotational speed of the motor 12 can be controlled.

  In addition, a suction valve 18 is provided in a suction passage 11 a of the compressor body 11, and the suction passage 11 a of the compressor body 11 can be opened and closed by opening and closing the suction valve 18. In addition, a control flow path 35 for communicating between the pressure receiving chamber of the suction valve 18 and the receiver tank 13 and an electromagnetic valve 34 for controlling the opening and closing of the control flow path 35 are provided. The opening and closing of the suction valve 18 can be controlled by controlling the opening and closing of the suction valve 34.

〔Control device〕
The control device 50 for controlling the frequency of the alternating current output from the inverter 31 and the opening / closing operation of the solenoid valve 34 is constituted by an electronic control device in which a predetermined program is stored. (Not shown) activates the program stored in advance and controls each unit according to the program, so that a target pressure setting unit 51, a PID calculation processing unit 52, a frequency control signal output unit 53, and an electromagnetic Each means of the valve control signal output unit 54 is realized.

  Table 1 explains the terms used in the following description.

(Target pressure setting section)
The target pressure setting unit 51 sets either the high set target pressure Pth or the low set target pressure Ptl as the target pressure Pt according to the selection made via the input unit.

[PID calculation processing unit]
The PID calculation processing unit 52 determines the discharge side pressure Pd of the compressor main body based on the discharge side pressure Pd of the compressor main body 11 detected by the pressure detection unit 33 and sets the target pressure (low set target) set by the target pressure setting unit 51. A target rotation speed (low set target rotation speed Ntl or high set target rotation speed Nth), which is a rotation speed that matches the pressure Ptl or the high set target pressure Pth, is calculated. In the present embodiment, a PID (Proportional-Integral-Differential) calculation is performed. Ask by

(Frequency control signal output unit)
The frequency control signal output unit 53 outputs the target pressure (the high set target pressure Pth or the low set target pressure Ptl) set by the target pressure setting unit 51 and the discharge side pressure Pd of the compressor body 11 detected by the pressure detection unit 33. On the basis of this, a control signal for causing the inverter 31 to output an alternating current having a frequency shown in Table 2 below is output.

(Solenoid valve control signal output section)
When the set target pressure is the low set target pressure Ptl according to the target pressure (the low set target pressure Ptl or the high set target pressure Pth) set by the target pressure setting unit 51, the solenoid valve control signal output unit 54 When the pressure detecting means 33 detects that the discharge-side pressure Pd of the compressor body 11 has reached the low-pressure set unload start pressure Pul, a control signal for opening the solenoid valve 34 is output, and the set target pressure becomes high. When the pressure is the set target pressure Pth, the control signal for opening the electromagnetic valve 34 when the pressure detecting means 33 detects that the discharge side pressure Pd of the compressor main body 11 has reached the high pressure set unload start pressure Puh. Output.

[Action, etc.]
In the gas generator 1 of the present invention configured as described above, when the adsorbent contained in the adsorption towers T1 and T2 is configured as a zeolite exhibiting adsorptivity to nitrogen and the gas generator 20 is configured as an oxygen PSA, The target pressure setting section 51 of the control device 50 provided in the compressor 10 sets the low set target pressure Ptl as the target pressure Pt, and the adsorbent contained in the adsorption towers T1 and T2 is converted into MSC (Molecular When the gas generator 20 is configured as nitrogen PSA as Sieving Carbon), the target pressure setting unit 51 is caused to set the high set target pressure Pth as the target pressure Pt.

  The frequency control signal output unit 53 refers to the target pressure set by the target pressure setting unit 51, and when the low set target pressure Ptl is set as the target pressure, the discharge of the compressor body detected by the pressure detection unit 33. The following control signal is output according to the side pressure Pd.

  When the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33 is lower than the low set target pressure Ptl, the frequency control signal output unit 53 outputs a frequency control signal for generating a maximum frequency fmax to the inverter 31. Output.

  Thus, the motor 12 to which the AC current having the maximum frequency fmax is input from the inverter 31 drives the compressor body 11 at the maximum rotation speed Nmax.

  When the drive of the compressor body 11 is continued by the motor 12 rotating at the maximum rotation speed Nmax, and the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33 rises and becomes equal to or higher than the low set target pressure Ptl, The frequency control signal output unit 53 outputs a frequency ftl corresponding to the low target rotation speed Ntl calculated by the PID calculation processing unit 52 based on the compressor-side discharge pressure Pd detected by the pressure detection unit 33. Is output to the inverter 31.

  As a result, the rotation speed of the motor 12 decreases as the discharge side pressure Pd of the compressor body 11 increases, and increases as the discharge side pressure Pd decreases.

  Then, when the discharge side pressure Pd of the compressor body 11 further increases due to the gas generator 20 entering the pressure equalization step and the consumption of the compressed air being stopped, the frequency control signal output unit 53 outputs the unload frequency fmin. A control signal is output to the inverter 31 to reduce the rotation speed of the motor 12 to the unload rotation speed Nmin which is the rotation speed of the lower limit in the speed control range.

  Even if the rotation speed of the motor 12 reaches the unload rotation speed Nmin, the discharge side pressure Pd of the compressor body 11 further increases while the compressor body 11 is in the suction state, and the pressure detection means 33 becomes the compressor body. When detecting that the discharge-side pressure Pd of No. 11 has risen to the low-pressure set unload operation start pressure Pul, the solenoid valve control signal output unit 54 of the control device 50 outputs a control signal for instructing the solenoid valve 34 to open. When the solenoid valve 34 is opened, the compressed air in the receiver tank 13 is introduced into the pressure receiving chamber of the suction valve 18 via the control flow path 35 and the suction valve 18 is closed, so that the suction to the compressor body 11 is stopped. To unload operation.

  From this state, the gas generator 20 enters the adsorption process from the pressure equalization process, and the discharge side pressure Pd of the compressor body 11 becomes lower than the low set target pressure Ptl (or the low set target pressure Ptl) due to the restart of the consumption of the compressed air. When the pressure drops below a preset low pressure setting return pressure between the pressure Ptl or more and the low pressure setting unload start pressure Pul, the solenoid valve control signal output is output based on the detection signal of the pressure detection means 33 that detects this pressure change. The unit 54 stops outputting the valve closing command signal to the solenoid valve 34 and closes the solenoid valve 34.

  As a result, the introduction of the compressed air into the pressure receiving chamber of the suction valve 18 via the control flow path 35 is stopped, the suction valve 18 is opened, and the compressor body 11 resumes the intake to start generating the compressed air. The frequency control signal output unit 53 of the control device 50 outputs to the inverter 31 a frequency signal for generating the frequency ftl corresponding to the low set target rotation speed Ntl obtained by the PID calculation processing unit 52.

  Thereafter, the discharge side pressure Pd of the compressor body 11 further drops below the low set target pressure Ptl due to an increase in the consumption of compressed air on the gas generator 20 side, and if this state is continued, the frequency control signal output The unit 53 outputs a control signal for generating the maximum frequency fmax to the inverter 31, and sets the rotation speed of the motor 12 to the maximum rotation speed Nmax.

  On the other hand, when the MSC (Molecular Sieving Carbon) is accommodated in the adsorption tower, the gas generator 20 is configured as a nitrogen PSA, and the target pressure setting unit 51 of the control device 50 is set to the high target pressure Pth as the target pressure. In the meantime, when the discharge side pressure Pd of the compressor body 11 is lower than the low set target pressure Ptl (Pd <Ptl), the frequency control signal output unit 53 of the control device 50 generates the maximum frequency fmax for the inverter. Outputs a frequency control signal.

  As a result, the motor 12 to which the AC current having the maximum frequency fmax is input from the inverter 31 drives the compressor body 11 at the maximum rotation speed Nmax, as in the case where the low set target pressure Ptl is set.

  By continuing to drive the compressor body 11 by the motor 12 rotating at the maximum rotation speed Nmax, the discharge side pressure Pd of the compressor body 11 detected by the pressure detection means 33 increases and becomes equal to or higher than the low set target pressure Ptl. In the range where the discharge side pressure Pd is less than the high set target pressure Pth (Ptl ≦ Pd <Pth), the frequency control signal output unit 53 of the control device 50 outputs the discharge side pressure Pd of the compressor body 11 detected by the pressure detection unit 33. Frequency control for obtaining the rated rotational speed Nr corresponding to the discharge-side pressure Pd based on the correspondence stored in the storage unit 55 in advance based on the frequency relationship for outputting the alternating current having the frequency fr corresponding to the rated rotational speed Nr. A signal is output to inverter 31.

  As a result, the motor 12 operates the motor 12 at the rated rotation speed Nr according to the discharge side pressure Pd of the compressor body 11 detected by the pressure detection means 33. As a result, the motor 12 is efficiently operated in a state where its performance is maximized even by changing the setting of the target pressure Pt.

  When the operation at the rated rotational speed Nr is continued, the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33 further increases and becomes equal to or higher than the high set target pressure Pth (Pd ≦ Pth). A frequency control signal output unit 53 outputs a frequency control signal for outputting a frequency fth corresponding to the high set target rotation speed Nth calculated by the PID calculation processing unit 52 based on the discharge side pressure Pd detected by the pressure detection unit 33. Output to the inverter 31, whereby the rotation speed of the motor 12 is controlled according to the change in the discharge side pressure Pd so as to maintain the discharge side pressure Pd of the compressor body 11 at the high set target pressure Pth.

  When the gas generator 20 enters the pressure equalizing step and the consumption of the compressed air stops, and the discharge side pressure Pd of the compressor body 11 detected by the pressure detecting means 33 further increases, the frequency control signal output unit 53 Outputs a control signal for outputting the unload frequency fmin to the inverter 31, whereby the rotation speed of the motor 12 decreases to the unload rotation speed Nmin which is the lower limit rotation speed in the speed control range.

  Even if the rotation speed of the motor 12 reaches the unload rotation speed Nmin, the discharge side pressure Pd of the compressor body 11 further increases while the compressor body 11 is in the suction state, and the pressure detection means 33 becomes the compressor body. When it is detected that the discharge side pressure Pd of No. 11 has risen to the high pressure set unloading start pressure Puh, the solenoid valve control signal output unit 54 of the control device 50 outputs a valve opening signal to the solenoid valve 34, and thereby the solenoid valve When the valve 34 is opened, the compressed air in the receiver tank 13 is introduced into the pressure receiving chamber of the suction valve 18 through the control flow path 35, the suction valve 18 is closed, and the suction of the compressor body 11 is stopped, so that the compression is performed. The machine 10 shifts to the unload operation.

  From this state, the gas generator 20 enters the adsorption step from the pressure equalization step, and the discharge side pressure Pd of the compressor main body 11 is equal to or less than the high set target pressure Pth (or the high set target pressure When the pressure drops below the preset high pressure setting return pressure between the pressure higher than Pth and the pressure lower than the high pressure set unloading start pressure Puh), the solenoid valve control signal output is output based on the detection signal of the pressure detecting means 33 which detects the pressure drop. The unit 54 stops the output of the valve opening command signal output to the solenoid valve 34 and closes the solenoid valve 34, whereby the introduction of the compressed air into the pressure receiving chamber of the suction valve 18 is stopped and the suction valve 18 It opens and the intake of the compressor main body 11 resumes.

  The frequency control signal output unit 53 of the control device 50 outputs to the inverter 31 a frequency control signal for generating a frequency fth corresponding to the high set target rotation speed Nth calculated by the PID calculation processing unit 52, and The discharge side pressure Pd of the main body 11 is controlled so as to be maintained at the high set target pressure Pth.

  Thereafter, the discharge side pressure Pd of the compressor body 11 further drops below the high set target pressure Pth due to an increase in the consumption of the compressed air on the gas generator 20 side, and if this state is continued, the frequency control signal output section 53 outputs a control signal for generating a frequency fr corresponding to the rated rotation speed Nr to the inverter 31. When the discharge side pressure Pd further decreases and falls below the low set target pressure Ptl, the maximum frequency fmax is generated. A control signal is output to the inverter 31 to increase the rotation speed of the motor 12 to the maximum rotation speed Nmax.

  As described above, in the compressor 10 for a gas generator according to the present invention, the target pressure Pt can be selected from the low set target pressure Ptl and the high set target pressure Pth, and the discharge side pressure Pd of the compressor body 11 can be selected. Is lower than the low set target pressure Ptl, the motor 12 is operated at the maximum rotational speed Nmax, and when the high set target pressure Pth is selected, the discharge side pressure of the compressor body 11 is equal to or higher than the low set target pressure Ptl and the high set target pressure Ptl is set. By operating at the rated rotational speed Nr within the range of pressures lower than the pressure Pth, the rotational speed is increased according to the rise of the discharge side pressure Pd while the output (kW) of the motor 12 is maintained at the rated output (37 kW as an example). Is reduced so that the performance of the motor is maximized and the compressed air can be efficiently supplied to the gas generator.

  In addition, the components of the compressor 10 provided on the discharge side of the compressor body 11, such as the receiver tank 13 and the dehumidifiers such as the oil separator 13a, the aftercooler 17, and the dryer 19 provided in the receiver tank, are connected to the motor 12 at the maximum rotational speed. Based on the amount of compressed air discharged from the compressor body 11 when operating at Nmax, the compressor is designed to have oil separation capacity, cooling capacity, and dehumidification capacity capable of processing this amount of compressed air. Since the maximum amount of compressed air generated in the main body 11 can be introduced into the gas generator 20 without delay, it is possible to suppress the occurrence of pressure loss occurring before the gas is introduced into the gas generator 20. Regardless of which of the low set target pressure Ptl and the high set target pressure Pth is set as the target pressure, an amount of compressed air close to the theoretical value is introduced into the gas generator 20. It is something that can be done.

  Specifically, in the compressor for a gas generator of the present invention, the rotation speed is increased so that the output of the motor becomes the rated output of 37 kW with the discharge side pressure reduced from 0.7 MPa to 0.6 MPa. According to the conventional inverter-driven compressor introduced in the "Problems to be Solved by the Invention" column, the increase in the amount of compressed air obtained by the same increase in the rotational speed was only about 4%. In the present embodiment, the increase in the amount of compressed air obtained by increasing the rotation speed is about 6.8%, and approaches the theoretical value of about 9% described in the "Problems to be Solved by the Invention" section. I was able to drive efficiently.

  As a result, in the gas generator 1 equipped with the compressor 10 of the present invention, the gas generator 1 having exactly the same structure is changed in the adsorbent contained in the adsorption towers T1 and T2, so that the nitrogen PS is also used as the oxygen PSA apparatus. It can also be used as a PSA device, and no matter what application it is used in, the compressor 10 does not generate unnecessary extra power, and the generated compressed air generates pressure loss. By introducing the gas into the gas generator 20 without causing the gas to be generated, the product gas can be produced more efficiently than a gas generator specifically designed as an oxygen PSA device or a nitrogen PSA device.

1 gas generator 10 compressor (inverter driven compressor)
11 Compressor body 11a Suction channel (of compressor body)
DESCRIPTION OF SYMBOLS 12 Motor 13 Receiver tank 13a Oil separator 14 Supply channel 15 Oil cooler 16 Oil supply channel 17 Aftercooler 18 Suction valve 19 Dryer 20 Gas generator 21 Outlet 22 Activated carbon tower 23 Buffer tank 24 Product gas outlet 31 Inverter 33 Pressure detection Means (pressure sensor)
34 solenoid valve 35 control flow path 50 control device 51 target pressure setting unit 52 PID calculation processing unit 53 frequency control signal output unit 54 solenoid valve control signal output unit 55 storage unit T1, T2 adsorption tower SV1 to SV8 solenoid valve
Nmax Maximum rotation speed
Nmin Unload rotation speed
fmax maximum frequency
fmin unload frequency
Pt target pressure
Ptl Low set target pressure
Pth high set target pressure
Ntl Low target speed
Nth high target rotation speed
Nr Rated speed
fr Frequency corresponding to the rated speed
ftl Frequency corresponding to low set target speed
fth Frequency corresponding to high set target rotation speed
Pu unloading start pressure
Pul Low pressure setting unload start pressure
Puh high pressure setting unload start pressure
Pd Compressor discharge pressure

Claims (9)

A compressor body that is used as a source gas for a pressure swing adsorption type gas generator and generates compressed gas, a motor that drives the compressor body, and changes the frequency of an alternating current input to the motor. An inverter is provided, and the frequency of the alternating current output by the inverter is changed in accordance with a change in the discharge side pressure of the compressor body to change the rotation speed of the motor to a maximum rotation speed which is an upper limit of a rotation speed control range. , A compressor for a gas generator that performs speed control to change the discharge side pressure of the compressor body to a preset target pressure by changing between unload rotation speeds as a lower limit.
The target pressure can be selectively set to a predetermined low set target pressure and a high set target pressure higher than the low set target pressure,
Correspondence of a change in rated rotation speed, which is a rotation speed at which the motor generates a rated output, to a change in discharge side pressure of the compressor body,
Correspondence relationship between a change in the discharge side pressure of the compressor body and a change in a low set target rotation speed that is a rotation speed that matches the discharge side pressure with the low set target pressure;
With respect to a change in the discharge side pressure of the compressor body, a correspondence relationship between a change in a high set target rotation speed, which is a rotation speed that matches the discharge side pressure with the high set target pressure, is obtained.
When the low set target pressure is set, and the discharge side pressure of the compressor body is less than the low set target pressure, the maximum rotation speed is set. Low set target rotation speed,
When the high set target pressure is set, and the discharge side pressure of the compressor body is less than the low set target pressure, the maximum rotational speed, the low set target pressure or more, and the high When the pressure is less than the set target pressure, the rated rotational speed is used.
And controlling the operation of the compressor for a gas generator by driving the motor. A suction valve for opening and closing a suction passage of the compressor body;
Setting a low pressure set unload start pressure that is a predetermined high pressure with respect to the low set target pressure, and a high pressure set unload start pressure that is a predetermined high pressure with respect to the high set target pressure;
When the low set target pressure is set, when the discharge side pressure of the compressor body becomes equal to or higher than the low pressure set unload start pressure while the motor is being driven at the low set target rotational speed, the high set target pressure is set. When the discharge side pressure of the compressor body becomes equal to or higher than the high pressure set unload start pressure while the motor is driven at the high target rotation speed, the suction valve is closed and the compressor is closed. The operation control method for a compressor for a gas generator according to claim 1, wherein the intake of the main body is stopped.   3. The compressor component provided on the discharge side of the compressor main body has a processing capacity corresponding to the amount of compressed gas discharged from the compressor main body at the maximum rotation speed. An operation control method for the compressor for a gas generator according to the above.   The component device is a dehumidifier for dehumidifying compressed gas generated in the compressor body, and the dehumidifying capacity of the dehumidifier corresponds to the amount of compressed gas discharged from the compressor body at the maximum rotation speed. The method for controlling the operation of a compressor for a gas generator according to claim 3, characterized in that: A compressor body that is used as a source gas for a pressure swing adsorption type gas generator and generates compressed gas, a motor that drives the compressor body, and changes the frequency of an alternating current input to the motor. An inverter, and changing the frequency of the alternating current output by the inverter in response to a change in the discharge side pressure of the compressor body detected by the pressure detecting means to increase the rotation speed of the motor to an upper limit of a control range of the rotation speed. For a gas generating apparatus having a control device for performing speed control for changing the discharge side pressure of the compressor body closer to a preset target pressure by changing between a maximum rotation speed of the compressor and an unload rotation speed of a lower limit. In the compressor of
In the control device,
A target pressure setting unit configured to selectively set a predetermined low set target pressure and a high set target pressure higher than the low set target pressure as the target pressure;
Correspondence of the change of the rated rotation speed, which is the rotation speed at which the motor generates the rated output, to the change of the discharge side pressure of the compressor body,
Correspondence of a change in a low set target rotation speed, which is a rotation speed that causes the discharge side pressure to match the low set target pressure, with respect to a change in the discharge side pressure of the compressor body, and
A storage unit that stores a correspondence relationship between a change in the discharge side pressure of the compressor body and a change in a high set target rotation speed that is a rotation speed that matches the discharge side pressure with the high set target pressure;
When the low set target pressure is set, and the discharge side pressure of the compressor body is less than the low set target pressure, the maximum rotation speed is set. Low set target rotation speed,
When the high set target pressure is set, and the discharge side pressure of the compressor body is less than the low set target pressure, the maximum rotational speed, the low set target pressure or more, and the high When the pressure is lower than the set target pressure, the rated rotational speed is used. When the pressure is equal to or higher than the high target pressure, the high set target rotational speed is used.
A frequency control signal output unit for outputting to the inverter a frequency control signal for outputting an alternating current having a frequency corresponding to the frequency of the compressor. A suction valve for opening and closing a suction passage of the compressor body is provided, and an electromagnetic valve for controlling introduction and discharge of an operating pressure to a pressure receiving chamber of the suction valve is provided, and the control device further controls opening and closing of the electromagnetic valve. A solenoid valve control signal output unit that outputs control signals is provided.
The storage unit of the control device stores a low pressure set unload start pressure that is a predetermined high pressure with respect to the low set target pressure and a high pressure set unload start pressure that is a predetermined high pressure with respect to the high set target pressure. I remember each,
When the low set target pressure is set, the discharge control pressure of the compressor body detected by the pressure detecting means while the motor is being driven at the low set target rotational speed by the frequency control signal output unit is the low pressure set pressure. When the pressure is equal to or higher than the load start pressure, when the high set target pressure is set, the frequency control signal output unit detects the compressor main body detected by the pressure detecting means during driving of the motor at the high set target rotational speed. When the discharge side pressure becomes equal to or higher than the high pressure set unload start pressure, the solenoid valve control signal output unit outputs a control signal for operating the solenoid valve to close the suction valve. The compressor for a gas generator according to claim 5, characterized in that:   7. The compressor according to claim 5, wherein components of the compressor provided on a discharge side of the compressor main body have a processing capacity corresponding to an amount of compressed gas discharged from the compressor main body at the maximum rotation speed. A compressor for a gas generator according to the above.   The component device is a dehumidifier for dehumidifying compressed gas generated in the compressor body, and the dehumidifying capacity of the dehumidifier corresponds to the amount of compressed gas discharged from the compressor body at the maximum rotation speed. The compressor for a gas generator according to claim 7, characterized in that: 9. A gas generator compressor according to any one of claims 5 to 8, and a pressure swing adsorption type gas generator which receives a supply of compressed gas from the gas generator compressor to produce a product gas. A gas generator characterized in that:

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