JP2003021073A - Compressed air producing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize minimization of control width of system pressure and power consumption and leveling of operation time in a compressed air producing system, when a separately installed number-of-compressors control device is omitted and a plurality of compressors are operated in parallel. SOLUTION: In this compressed air producing system, variable speed compressors or constant speed compressors are combined in parallel, and one variable speed compressor (base load machine) unit 15 is provided with a control part 5 for externally operating at least one or more other variable or constant speed compressor (backup machine) unit 16 and receiving a failure state of these compressors. Thus, an independent, separately installed externally control device can be omitted, cost and installation space required for the compressed air producing system can be minimized, the control width of system pressure and power consumption can be minimized, and the operation time can be leveled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed air manufacturing system, and a variable speed compressor (base load machine) having a function of externally controlling another air compressor (also simply referred to as a compressor), The present invention relates to a control method in the case of combining a plurality of constant speed or variable speed compressors (backup machines) having a function of being controlled by external operation.

[0002]

2. Description of the Related Art Conventionally, there has been known a compressor number control apparatus having a function of performing power saving by performing alternate operation control or number control of a plurality of compressors (for example, Japanese Patent Laid-Open No. 8-2.
96565, Japanese Unexamined Patent Publication No. 8-296566, Japanese Patent No. 3002118, etc.). These unit number control methods describe that a plurality of compressors are controlled by a unit number control device to save power.

[0003]

In the above conventional technique, the number-of-units control device controls the capacity of a plurality of compressors and the number of operating units to save power. However, a unit control device is required in addition to the plurality of compressors, and construction and installation space for the unit control device are also required. Especially for compressors with a small number, it has a great weight in terms of cost.

Further, in the above-mentioned conventional technique, the number of rotations of the compressor is constant, and control is performed only for a plurality of constant speed compressors that can be loaded / unloaded and can be operated / stopped. It is possible to control only a plurality of variable speed compressors that control the capacity by varying the rotation speed, but there is no established method to control a constant speed compressor and a variable speed compressor by a single unit controller. .

It is known that a variable speed compressor capable of varying the rotational speed of the compressor has the best specific power characteristic than a constant speed compressor which performs load / unload and operation / stop control. However, in the above-mentioned conventional technique, at least one compressor performs load / unload control, so that it is not possible to perform optimum unit number control including the variable speed compressor, which means that further power saving is achieved. There was room and it was a problem.

Therefore, in the compressed air manufacturing facility described in Japanese Patent Laid-Open No. 2000-161237, a plurality of variable speed compressors and constant speed compressors are operated by following the pressures of the discharge air to save power. It is trying to make it. However,
In this method, since the pressure settings of the respective compressors are shifted and made to follow, it is necessary to widen the pressure control width of the system.

An object of the present invention is to suppress wasteful unloading operation in a compressed air manufacturing system as much as possible, and to save power as much as possible without using a separately installed unit control device, and It is to equalize the operation time of multiple compressors while saving power.

[0008]

The above object is to provide a base load machine comprising one variable speed air compressor, and a constant speed or a variable speed whose start, stop, and rotation speeds are controlled by the base load machine. At least one consisting of an air compressor
This is achieved by a compressed air manufacturing system composed of one or more backup machines.

That is, according to the present invention, since the operation of the compressor of the entire system and the discharge air amount can be adjusted by the base load machine, a separate installation for controlling the number of operating compressors of the entire system which has been conventionally used is installed. The controller can be omitted. Moreover, since the unloading operation of the backup machine can be suppressed, it becomes possible to save power and level the operation time of a plurality of compressors.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The outline of the present embodiment is that one variable speed compressor 7 is used as a base load machine, one constant speed compressor 8 is used as a backup machine, and it is installed separately in a compressed air manufacturing system combining these compressors. That is, the operation of the base load machine 7 itself and the backup machine 8 is controlled by the judgment of the base load machine 7 without using the control device.

This eliminates the need for a control device which has conventionally been used to control the number of compressors in the entire system, and it is possible to suppress the wasteful unloading operation of the compressor. It has become possible to save energy by improving the overall operating efficiency.

In the following, a system composed of one base load machine 7 which issues a control command and one backup machine 8 which receives a control command from the base load machine 7 will be described. The backup machine that receives the command may have a constant speed compressor, a variable speed compressor, or a system configuration in which a plurality of them are mixed.

[First Embodiment] FIG. 1 is a block diagram showing an embodiment of a compressed air manufacturing system of the present invention. FIG. 2 is a control time chart showing an example of the operating method of the present embodiment.

The compressed air manufacturing system of this embodiment has two compressor units 15 each having a compressor and a controller.
16 and an air tank 1 connected to each compressor unit by compressed air pipes 12 and 14 for converging and storing discharged compressed air, and means for detecting the pressure of the compressed air in the air tank 1. The pressure sensor 2 is provided, and the compressed air is supplied from the air tank 1 to the compressed air use line.

The compressed air use line may be used as the air tank 1 in some cases, for example, when the capacity of the compressed air use line is sufficiently large. In some cases, the pressure sensor 2 and the pressure sensor 3 described later are combined into one pressure sensor, and the detection pipe of this pressure sensor is connected to the air on the downstream side of the check valve 9 and the check valve 10 of each compressor unit. It may be connected to a pipe and used.

The compressor unit 15 includes a compressor 7 which is a variable speed compressor, a controller 5 for controlling the compressor 7 itself and other compressors, and a discharge air connected to a compressed air outlet of the compressor 7. A pipe 11, a check valve 9 provided in the discharge air pipe 11, and a pressure sensor 3 for detecting the compressed air pressure on the downstream side of the check valve 9 and on the upstream side of the compressed air outlet of the compressor unit 15. It is configured to include.

The outputs of the pressure sensor 3 and the pressure sensor 2 are input to the control unit 5 to detect the pressure of the compressor unit 15 or the compressed air manufacturing system. Also, the compressor 7
Is the capacity control lower limit rotation speed when the discharge air amount reaches 30% of the rated value.

The compressor unit 16 includes a compressor 8 which is a constant speed compressor, a control unit 6 which controls the compressor 8 itself, and a discharge air pipe 13 which is connected to a compressed air outlet of the compressor 8.
The pressure installed in the check valve 10 inserted in the discharge air pipe 13 and the detection pipe connected to the discharge air pipe 13 downstream of the check valve 10 and upstream of the compressed air outlet of the compressor unit 16. The sensor 4 is included.

The pressure sensor 4 can detect the pressure of the compressor unit 16 or the compressed air manufacturing system, and the output of the pressure sensor 4 is input to the control unit 6.
The control units 5 and 6 are collectively referred to as control means, and the pressure sensors 2, 3 and 4 are collectively referred to as pressure detection means.

In the present embodiment, from the control unit 5 of the compressor unit 15, the external operation signal wiring for controlling the compressor unit 16, that is, the operation of the compressor unit 16,
The signal wiring for stopping is connected to the external operation input section of the control section 6.

In addition, when the compressor unit 16 fails, the fault signal wiring from the control unit 6, that is, the output signal wiring indicating that the compressor unit 16 has failed, is the control unit 5.
Is connected to the fault input section of.

The pressure sensor 4 of the compressor unit 16
May be a pressure switch other than the pressure sensor. Further, the communication means for the external operation signal wiring or the failure signal wiring described above is an ON / OFF signal of a relay or the like, an analog signal to be judged by a change in voltage or current, RS232C or RS485.
Any signal such as a digital signal such as

In this embodiment, the output of each of the two compressors is 37 kW, and the capacity of the air tank is 1.24 m ³ .
Both of the compressors 7 and 8 are supposed to perform unloading by the suction throttle valve.

In the following, an unloading system in which the opening degree of the suction throttle valve is continuously reduced is a U-type unloading method, in which the suction throttle valve is closed and at the same time the discharge pressure of the compressor is reduced (pressure reduction on the upstream side of the check valve). The unloading method that starts) is called I-type unloading, and the operating states other than unloading are called loading.

In this example, the following pressure settings are made. The control pressure setting for keeping the discharge pressure of the variable speed compressor unit 15 within a fixed value is set to 0.66 MPa (first pressure: the number of revolutions of the compressor is changed to reach this pressure), and the compressor 7 At the lower limit of rotation speed control, the rotation speed is kept constant and the suction throttle valve is closed, and at the same time, pressure reduction of the discharge pressure of the compressor (pressure reduction on the upstream side of the check valve) is started. 0.68 MPa (second pressure)
And

While the compressor unit 15 is automatically stopped, the return pressure setting is set to 0 for restarting when the pressure drops.
The pressure was set to 66 MPa (third pressure), and the control pressure setting (I-type unloading start pressure setting) of the constant speed compressor unit 16 was set to 0.69 MPa (fourth pressure).

The return pressure setting from the I-type unloading (pressure setting for automatic restart) is 0.64 MPa (fifth pressure), and the U-type unloading starting pressure setting is 0.69.
It was set to MPa. In the constant speed compressor 8, the control pressure setting and the U-type unloading starting pressure setting are the same pressure setting, but the I-type unloading is controlled first.

The above pressure settings have the following relationship. That is, for the variable speed compressor 7, the first pressure to be maintained by the rotation speed control and the second pressure higher than the first pressure at which the unloading is started are set, and the air usage amount is increased. A fourth pressure, which is higher than the second pressure, is set as the pressure at which unloading is started for the constant speed compressor that should be stopped first when the pressure decreases.

Further, the pressure (third pressure) at which the variable speed compressor is started from the stop is set to the same as the first pressure (the pressure may be set lower than the first pressure). The pressure (fifth pressure) at which the constant speed compressor starts from stop is
It is set lower than the first pressure.

However, in this example, the automatic stop function of the constant speed compressor 8 is canceled, and a stop signal is input to the control unit 6 of the constant speed compressor or a failure occurs by manual or external operation signal input. I try not to stop unless I get up. Further, in this example, the I-type unloading function of the constant speed compressor is canceled, and when the pressure rises, the U-type unloading is started.

FIG. 2 shows an example of a control time chart in this embodiment. The control time chart of FIG.
When the maximum discharge air amount of each of the 7 kW compressor units 15 and 16 is 100% and the two units are 200%,
The used air amount ratio (parameter indicating the used air amount based on the maximum discharge air amount of 200%) is from 200% to 0%, 0%
Represents the change in the air tank pressure, the inverter output frequency and the power consumption ratio of the compressor unit 15 which is the variable speed compressor, and the power consumption ratio of the compressor unit 16 which is the constant speed compressor when the air tank pressure changes from 200 to 200%. There is.

The change in the operating state of the compressor due to the change in the used air amount ratio will be described below with reference to FIG. Compressor units 15 and 16 both output 100%, air tank 1
It starts from the state of operating at a pressure of 0.66 MPa.

First, in the block shown in FIG. 2a, the pressure in the air tank 1 is 0.66 MPa and the air volume ratio is 200.
%, The compressor unit 16 becomes a load because the pressure of the air tank 1 is lower than the fourth pressure, and the compressed air discharge amount and the power consumption both operate at 100%. The unit 15 reduces the rotational speed to keep the pressure within a certain level and also reduces the power consumption.

It is already known that the specific power of the constant speed compressor deteriorates in proportion to the decrease in the compressed air discharge amount, whereas the specific power of the compressor unit 15 hardly changes, and the description thereof will be omitted. However, the compressor unit 16 has the best specific power because it operates at 100% of the compressed air discharge amount and power consumption, and the compressor unit 15 also has a substantially proportional decrease in power consumption when the compressed air discharge amount is reduced. The power saving effect is great because the specific power does not change.

In the block b of FIG. 2, when the pressure in the air tank 1 is 0.66 MPa, the used air amount ratio is 130% to 100%.
Even when the compressor unit 16 changes to, the compressor unit 16 continues to load because the pressure in the air tank 1 is lower than the fourth pressure, and the compressor unit 15 has already reached the minimum rotation speed. If the ratio decreases, the air tank pressure will be 0.68M
Raise to Pa. Since the pressure in the air tank 1 becomes the second pressure, the compressor unit 15 becomes the I-type unload.

In the block c in FIG. 2, the used air amount ratio is 1
When it becomes less than 00%, the pressure in the air tank 1 is 0.69 MPa.
Therefore, the compressor unit 16 becomes equal to or higher than the fourth pressure, a stop signal is input from the control unit 5 to the control unit 6, and the compressor unit 16 stops. Compressor unit 1
When the compressed air discharge amount of 6 becomes 0%, the compressed air discharge amount of about 100% or less becomes insufficient, and the pressure in the air tank 1 decreases.

When the pressure in the air tank 1 drops to the first pressure, the compressor unit 15 switches from the I-type unloading to the rotation speed control (load) to increase the rotation speed and replenish the deficient air amount. Since the compressor unit 15 replenishes the shortage of air, the pressure in the air tank 1 is 0.66M.
Raise to Pa. Since the pressure in the air tank 1 does not drop to the fifth pressure, the compressor unit 16 remains stopped.

In the block d in FIG. 2, when the pressure in the air tank 1 is 0.66 MPa and the ratio of the amount of air used changes from 100% to 30%, the compressor unit 16 is higher than the fifth pressure in the air tank 1. Since the pressure is high, the stopped state is maintained, and the compressor unit 15 lowers the rotation speed to keep the pressure within a certain level and reduces the power consumption.

In the block e of FIG. 2, even when the air volume ratio changes from 30% to 0% when the pressure in the air tank 1 is 0.66 MPa, the compressor unit 16 is higher than the fifth pressure in the air tank 1. Since the pressure is high, the stopped state is maintained, and since the compressor unit 15 has already reached the minimum rotation speed, the air tank pressure rises to 0.68 MPa when the used air amount ratio decreases. Since the pressure in the air tank 1 becomes the second pressure, the compressor unit 15 becomes the type I unload.

In the block f in FIG. 2, it takes 3 minutes for the pressure in the air tank 1 to drop from the second pressure to the first pressure, so the compressor unit 15 automatically stops.

In the g block of FIG. 2, the used air amount ratio is 0.
%, And the pressure in the air tank 1 drops to 0.66 MPa or less, the compressor unit 15 is restarted because the pressure in the air tank 1 becomes lower than the first pressure, and the rotation speed control is switched.

In the h block of FIG. 2, the used air amount ratio is 3
When it changes from 0% to less than 100%, the compressor unit 15 increases the rotation speed to the maximum rotation speed, keeps the pressure of the air tank 1 within a certain level, and reduces the compressed air discharge amount to 100%.
Up to.

In the i block of FIG. 2, the used air amount ratio is 1
If less than 00% continues, the compressor unit 15 keeps the rotation speed constant at the maximum rotation speed and continues loading.

In the block j of FIG. 2, the used air amount ratio is 1
When it changes from 00% to 130%, the pressure of the air tank 1 drops to 0.64 MPa, and the compressor unit 16 has the pressure of the air tank 1 lower than the fifth pressure. An operation signal (restart signal) is input to the section 6, and the compressor unit 16 starts operation and continues loading.

When the compressor unit 16 is loaded, the amount of compressed air discharged increases by 100%, so the pressure in the air tank 1 rises to 0.66 MPa. Compressor unit 1
No. 5 lowers the rotation speed to suppress the further increase in the pressure of the air tank 1, but the rotation speed decreases to the minimum rotation speed, and the pressure of the air tank 1 further increases to the second pressure. The compressor unit 15 is the type I unload.

In the k block shown in FIG. 2, the used air amount ratio is 1
When it changes from 30% to less than 200%, the pressure in the air tank 1 tries to drop from 0.66 MPa, so the compressor unit 15 switches to rotation speed control to stabilize at 0.66 MPa, and reaches the maximum rotation speed. Increase the rotation speed.

As described above, the constant speed compressor does not unload at the time of control switching as in the operation of blocks a to k. The fact that the constant speed compressor is either in the load or in the automatic stop state means that the specific power is the best.
When combined with the fact that the compressor unit 15 adjusts the compressed air discharge amount with respect to the change in the used air amount ratio, it can be seen that the two units perform the maximum power saving operation.

It is necessary to provide the compressor unit 16 with a stop time limit, and when the number of times the air amount ratio is increased or decreased by 100% is large, the compressor unit 16 cannot be stopped until the stop time limit has elapsed. Therefore, in the block c in FIG. 2, since the stop signal is not input from the control unit 5 to the control unit 6, the compressor unit 16 is switched to the U-type unloading. When the stop time limit has elapsed, the stop signal is input from the control unit 5 to the control unit 6, and the compressor unit 16 is stopped.

When the I type unloading function of the compressor unit 16 is used, at the time when the pressure of the air tank 1 becomes 0.69 MPa in the block c in FIG. Input the unload signal and press the compressor unit 16
Switches to type I unloading. If the pressure of the air tank 1 does not drop to the fifth pressure while the compressor unit 16 continues the I-type unloading for 3 minutes, a stop signal is input from the control unit 5 to the control unit 6, and the compressor unit 16 stops.

When the compressor unit 15 fails, and the controller 5 does not fail, the controller 5 transfers to the controller 6.
Signals such as operation, stop, load, and unload are input to control the compressor unit 16 to suppress the pressure drop in the air tank 1 to a minimum.

When the compressor unit 16 fails, the controller 6 inputs a failure signal to the controller 5, and the controller 5 informs the outside that the compressor unit 16 has failed.
The second failure signal is output instead of the self-device, the control of the compressor unit 15 is switched to the independent operation (original capacity control) and continued, and the decrease in the pressure of the air tank 1 is suppressed to the minimum.

The failure signal from the control section 6 to the control section 5 may be an operation answer signal, and the control section 6 to the control section 5 may be used.
An operation answer signal input to the control unit 5, that is, a signal for confirming that the compressor unit 16 is operating, which returns from the control unit 6 to the control unit 5 in response to the input of the operation signal from the control unit 5 to the control unit 6, Is no longer input, the control unit 5 determines that the compressor unit 16 has failed.

When the compressor unit 16 fails, it is not necessary to input a failure signal or an operation answer signal from the control unit 6 to the control unit 5. In this case, the control unit 5 cannot determine whether or not the compressor unit 16 has failed, but since the control method is not changed and the capacity control is continued as it is, the decrease in the pressure of the air tank 1 is suppressed to the minimum.

When the compressor unit 15 is a constant speed compressor and the compressor unit 16 is a variable speed compressor, the input / output of the operation / stop signal and the input / output of the load / unload signal are simply reversed. Other than that, the content is the same as that of the above-described embodiment.

[Second Embodiment] A second embodiment of the present invention will be described with reference to the block diagram of the compressed air manufacturing system of FIG. 1 and the control time chart of FIG.

The compressed air manufacturing system of this embodiment has two
This is an example in which two compressors are used and the output of the variable speed compressor is larger than that of the constant speed compressor. Two
Since the configuration is the same as that of the first embodiment except for the difference in the output of the compressor of the stage and the pressure setting, the same contents will be omitted.

In this embodiment, the compressor output of the compressor unit 15 which is a variable speed compressor is 37 kW, and the compressor output of the compressor unit 16 which is a constant speed compressor is 22 kW.
And the air tank capacity was 1.24 m ³ .

The control pressure setting for keeping the discharge pressure of the variable speed compressor unit 15 within a fixed value is 0.66 MPa.
(First pressure), the rotational speed control lower limit rotational speed of the compressor 7, the rotational speed is kept constant, the suction throttle valve is closed, and at the same time, the pressure reduction of the discharge pressure of the compressor is started. The setting is set to 0.68 MPa (second pressure), and the return pressure setting for restarting when the pressure decreases during the automatic stop of the compressor unit 15 is set to 0.66 MPa (third pressure).
Pressure).

Further, the control pressure setting of the constant speed compressor unit 16 is set to 0.69 MPa (fourth pressure), and the return pressure setting from the type I unloading and the automatic restart pressure setting are set to 0.64 MPa (fifth setting). Pressure), and the U-type unloading starting pressure setting was set to 0.69 MPa. The compressor 8
In the above, although the control pressure setting and the U-type unloading starting pressure setting are the same pressure setting, the I-type unloading is controlled first.

The pressure setting in this embodiment has the following relationship. That is, the first pressure to be maintained by the rotation speed control for the variable speed compressor and the second pressure higher than the first pressure for starting the unloading are set.

For the constant speed compressor which should be stopped first when the air consumption decreases, the fourth pressure higher than the second pressure
Is set as the pressure at which unloading starts, and the pressure (third pressure) at which the variable speed compressor starts from stop is:
The setting is the same as the first pressure (the pressure may be set lower than the first pressure). The pressure (fifth pressure) at which the constant speed compressor is started from the stop is set to be lower than the first pressure.

However, in this example, the automatic stop function of the constant speed compressor is released, and a stop signal is input to the control unit 6 of the constant speed compressor or a failure occurs by manual or external operation signal input. I try not to stop unless I do. Further, in this embodiment, the I-type unloading function of the constant speed compressor is canceled, and when the pressure increases, the U-type unloading is started.

In the control time chart of the second embodiment shown in FIG. 3, the maximum discharge air amounts of the compressor unit 15 having an output of 37 kW and the compressor unit 16 having an output of 22 kW are 100% and 60%, respectively. When the two units are set to 160%, the used air amount ratio (parameter indicating the used air amount based on the maximum discharge air amount of 160%) is 160.
% To 0%, air tank pressure when changing from 0% to 160%, and compressor unit 15 which is a variable speed compressor
Of the inverter output frequency and power consumption ratio, the power consumption ratio of the compressor unit 16 which is a constant speed compressor, and the like.

The maximum discharge air amount of the compressor unit 16 is set to 6
The reason why 0% is set is that the maximum discharge air amount of the compressor unit 16 is 60% when compared with the maximum discharge air amount of the compressor unit 15 of 100%. Further, when the maximum output of the compressor unit 15 is 100%, the maximum output of the compressor unit 16 is 60%.

The change in the operating state of the compressor due to the change in the used air amount ratio will be described below with reference to FIG. Compressor unit 15 outputs 100%, compressor unit 16 outputs 6%
It starts from the state where it is operating at 0% output and the pressure of the air tank 1 is 0.66 MPa.

First, in the block a of FIG. 3, the pressure in the air tank 1 is 0.66 MPa, and the used air amount ratio is 160% to 9%.
When it changes to 0%, the compressor unit 16 becomes a load because the pressure of the air tank 1 is lower than the fourth pressure, and the compressed air discharge amount and the power consumption both operate at 60%. Reduces the number of rotations to keep the pressure within a certain level and reduces the power consumption.

It is already known that the specific power of the constant speed compressor deteriorates in proportion to the decrease in the compressed air discharge amount, whereas the specific power of the compressor unit 15 is almost unchanged, and the description thereof is omitted. However, since the compressor unit 16 operates at a compressed air discharge amount and power consumption of 60%, the specific power is the best, and when the compressed air discharge amount is reduced, the compressor unit 15 also has a substantially proportional power consumption reduction. In order to
Since the specific power does not change, the power saving effect is great.

In the block b in FIG. 3, the used air amount ratio is 9
When it becomes 0% or less, the rotation speed of the compressor unit 15 becomes the minimum rotation speed. In response to this, a stop signal is input from the control unit 5 to the control unit 6, and the compressor unit 16 stops. When the compressed air discharge amount of the compressor unit 16 becomes 0%, it is about 60.
%, The amount of compressed air discharged becomes insufficient, and the pressure in the air tank 1 decreases.

When the pressure in the air tank 1 drops to the first pressure, the compressor unit 15 increases the rotation speed from the minimum rotation speed to replenish the insufficient amount of air. Since the compressor unit 15 replenishes the shortage of air, the pressure in the air tank 1 rises to 0.66 MPa again. Since the pressure in the air tank 1 does not drop to the fifth pressure, the compressor unit 16 remains stopped.

In the block c in FIG. 3, when the pressure in the air tank 1 is 0.66 MPa and the used air amount ratio changes from 90% to 30%, the compressor unit 16 is higher than the fifth pressure in the air tank 1. Since the pressure is high, the stopped state is maintained, and the compressor unit 15 lowers the rotation speed to keep the pressure within a certain level and reduces the power consumption.

In the block d in FIG. 3, even when the air volume ratio changes from 30% to 0% when the pressure in the air tank 1 is 0.66 MPa, the compressor unit 16 is higher than the fifth pressure in the air tank 1. Since the pressure is high, the stopped state is maintained, and since the compressor unit 15 has already reached the minimum rotation speed, the air tank pressure rises to 0.68 MPa when the used air amount ratio decreases. Further, since the pressure in the air tank 1 becomes the second pressure, the compressor unit 15 becomes the I-type unload.

In the block e in FIG. 3, since the pressure in the air tank 1 has decreased to 3 minutes from the second pressure to the first pressure, the compressor unit 15 is automatically stopped.

In the f block of FIG. 3, the used air amount ratio is 0.
%, And the pressure in the air tank 1 drops to 0.66 MPa or less, the compressor unit 15 is restarted because the pressure in the air tank 1 becomes lower than the first pressure, and the rotation speed control is switched.

In the block g in FIG. 3, the air quantity ratio used is 3
When it changes from 0% to less than 100%, the compressor unit 15 increases the rotation speed to the maximum rotation speed, keeps the pressure of the air tank 1 within a certain level, and reduces the compressed air discharge amount to 100%.
Up to.

In the h block shown in FIG. 3, the used air amount ratio is 1
When less than 00% is maintained, the compressor unit 15 keeps the rotation speed constant at the maximum rotation speed and continues loading.

In the i block of FIG. 3, the used air amount ratio is 1
When the pressure changes in the air tank 1 to more than 00% and the pressure in the air tank 1 decreases to 0.64 MPa, the pressure in the air tank 1 of the compressor unit 16 becomes lower than the fifth pressure. An operation signal (restart signal) is input to the compressor unit 16, and the compressor unit 16 starts operation and continues loading.

When the compressor unit 16 is loaded, the compressed air discharge amount is increased by 60%.
Pressure rises to 0.66 MPa. The compressor unit 15 reduces the rotation speed to 24 Hz (equivalent to 60%),
After that, the number of revolutions is increased with an increase in the used air amount ratio.

In the j block of FIG. 3, the used air amount ratio is 1
When it rises to less than 60%, the pressure in the air tank 1 is 0.66.
Since it is going to decrease from MPa, the compressor unit 15
Will further increase the rotation speed to stabilize at 0.66 MPa and increase the rotation speed to the maximum rotation speed.

As described above, like the operations of blocks a to j, the constant speed compressor does not unload at the time of switching the control. The fact that the constant speed compressor is either in the load or in the automatic stop state means that the specific power is the best.
When combined with the fact that the compressor unit 15 adjusts the compressed air discharge amount with respect to the change in the used air amount ratio, it can be seen that the two units perform the maximum power saving operation.

When it is necessary to provide the compressor unit 16 with a stop time limit, and when the number of times of going up and down beyond the range of the used air amount ratio of 60% to 100% is large, the compressor unit 16 is kept until the stop time limit has elapsed. I can't stop it. Therefore, in the block b of FIG. 3, since the stop signal is not input from the control unit 5 to the control unit 6, the compressor unit 1
6 switches to U-type unloading. When the stop time limit has elapsed, a stop signal is input from the control unit 5 to the control unit 6,
At this time, the compressor unit 16 is stopped.

When the I-type unloading function of the compressor unit 16 is used, at the time when the rotation speed of the compressor unit 15 reaches the minimum rotation speed in the block b of FIG. The unload signal is input to the compressor unit 16, and the compressor unit 16 is switched to the type I unload. While the compressor unit 16 continues the type I unload for 3 minutes, the air tank 1
When the pressure of the compressor unit 16 does not decrease to the fifth pressure, the stop signal is input from the control unit 5 to the control unit 6, and the compressor unit 16
Will stop.

When the compressor unit 15 has failed, and the control unit 5 has not failed, the control unit 5 inputs signals such as operation, stop, load and unload to the control unit 6, and the compressor unit 16 Is controlled to minimize the pressure drop in the air tank 1.

When the compressor unit 16 fails, the controller 6 inputs a failure signal to the controller 5, and the controller 5 notifies the outside that the compressor unit 16 has failed.
The second failure signal is output instead of the self-device, the control of the compressor unit 15 is continuously switched to the independent operation (original capacity control), and the decrease in the pressure of the air tank 1 is suppressed to the minimum.

The failure signal from the control section 6 to the control section 5 may be an operation answer signal, and the control section 6 to the control section 5 may be used.
An operation answer signal input to the control unit 5, that is, a signal for confirming that the compressor unit 16 is operating, which returns from the control unit 6 to the control unit 5 in response to the input of the operation signal from the control unit 5 to the control unit 6, Is no longer input, the control unit 5 determines that the compressor unit 16 has failed.

When the compressor unit 16 fails, it is not necessary to input a failure signal or an operation answer signal from the control section 6 to the control section 5. In this case, the control unit 5 cannot determine whether the compressor unit 16 has failed, but since the capacity control is continued without changing the control method, the decrease in the pressure of the air tank 1 is suppressed to the minimum.

When the compressor unit 15 is the constant speed compressor and the compressor unit 16 is the variable speed compressor, the input / output of the operation / stop signal and the input / output of the load / unload are only reversed. Other than that, the content is the same as that of the above-described embodiment.

The first embodiment is the compressor unit 1
While the condition for stopping 6 is determined by the fourth pressure above the second pressure of the compressor unit 15, in the second embodiment, the rotation speed of the compressor unit 15 is the minimum rotation speed. Since the compressor unit 16 is stopped when the number reaches the number, it is possible to narrow the pressure setting range of the entire compressed air manufacturing system as compared with the first embodiment.

[Third Embodiment] A third embodiment of the present invention is shown in FIG. 1, which is a block diagram of the compressed air manufacturing system, and FIG. 4 is a control time chart showing changes in operating conditions.
The control time chart of the compressed air manufacturing system of FIG.

The compressed air manufacturing system of this embodiment has two
This is an example of using one variable speed compressor. Except that the two co-compressors are variable speed compressors, they are the same as in the first embodiment, so description of the same contents will be omitted.

In this embodiment, the output of each of the two compressors was 37 kW, and the capacity of the air tank was 1.24 m ³ .
Further, the control pressure setting for keeping the discharge pressure of the compressor units 15 and 16 which are variable speed compressors within a fixed value is set to 0.
It was set to 67 MPa (first pressure).

Further, at the rotational speed control lower limit rotational speed of the compressor 7, the rotational speed is kept constant and the suction throttle valve is closed, and at the same time, the I-type unload start pressure setting for starting the pressure reduction of the discharge pressure of the compressor is set to 0. Set the recovery pressure to 0.69MPa (second pressure) and restart it when the pressure decreases while automatically stopping the compressor units 15 and 16.
It was set to a (third pressure).

The relationship of pressure setting for these two variable speed compressors is as follows. That is, for the variable speed compressor, the first pressure to be maintained by the rotation speed control,
A second pressure higher than the first pressure at which unloading starts is set, and a pressure at which the variable speed compressor starts from a stop is set at a third pressure lower than the first pressure ( It may be equal to or lower than the first pressure).

However, in this embodiment, the automatic stop function of the compressor unit 16 which is a variable speed compressor is canceled, and a stop signal is input to the control unit 6 of the variable speed compressor by manual or external operation signal input. It does not stop unless there is a failure.

The control time charts of FIGS. 4 and 5 are:
When the maximum discharge air amount of each of the compressor units 15 and 16 with an output of 37 kW is 100%, the ratio of the amount of air used when the two compressors are 200% (the amount of air used is the maximum amount of discharge air 20
0% as a reference) changes in the operating conditions of the two variable speed compressors (Fig. 4) when the values change as shown in the figure, and the air tank pressure and the compressor that is the variable speed compressor. The change in the power consumption ratio of the units 15 and 16 (FIG. 5) is shown.

Hereinafter, changes in the operating condition of the compressor due to changes in the used air amount ratio and time will be described with reference to FIGS. 4 and 5. Further, in the present embodiment, the operation time of the two variable speed compressors is leveled, so that the control unit 5 is provided with an operation timer. The variable speed compressor has a function to replace the base load machine and the backup machine. The compressor unit 15 is set as a base load machine and the compressor unit 16 is set as a backup machine, and the operation timer of the control unit 5 starts from 0.

First, in the block on the first day in FIG. 4, the operation timer of the control unit 5 starts integration at the same time when the compressor unit 15 which is a variable speed compressor is operated, and the air volume ratio is 100% for one day. Since it is below, the compressor unit 15
Performs capacity control, and the compressor unit 16 maintains a stopped state.

In the block on the second day of FIG. 4, the operation timer of the control unit 5 is timed up, and the air amount ratio used at that time is 100% or less. At the same time the unit 15 automatically stops,
The compressor unit 16 of the backup machine, which was stopped,
An operation signal is input from the control unit 5 to the control unit 6 to start the operation.

At this point, the base load machine and the backup machine are exchanged, and the operation timer is initialized to 0 and the integration is restarted. As it is, the compressor unit 16 controls the capacity, and the compressor unit 15 maintains the automatic stop state.

In the block on the third day in FIG. 4, the integration of the operation timer of the control unit 5 has timed up, and the used air amount ratio at that time is 100% or less, so the compressor of the backup machine that was automatically stopped. The unit 15 starts operation, and at the same time, the compressor unit 1 of the base load machine that was operating
6 is stopped by the stop signal being input from the control unit 5 to the control unit 6.

At this time, when the base load machine and the backup machine are exchanged, the operation timer is initialized to 0, integration is started again, the compressor unit 15 controls the capacity, and the compressor unit 16 maintains the stopped state. .

In this third day block, 2
Since the used air amount ratio is 100% or more, the compressor unit 16 which is the backup machine starts operation by receiving an operation signal from the control unit 5 to the control unit 6. Details of this will be described later with reference to FIG. 5 during the time X1 in FIG.

In the block on the 4th day in FIG. 4, the operation timer of the control unit 5 is timed up, and the ratio of the amount of air used at that time is 100% or less. At the same time the unit 15 automatically stops,
The compressor unit 16 of the backup machine, which was stopped,
An operation signal is input from the control unit 5 to the control unit 6 to start the operation.

At this time, the base load machine and the backup machine are exchanged, and the operation timer is initialized to 0.
Then, the integration starts again. In addition, the compressor unit 1
6 performs capacity control, and the compressor unit 15 maintains an automatic stop state. During this one day, since the ratio of the amount of air used is 100% or more during the time X2, the compressor unit 15 which is the backup machine starts operation. Details of this will be described later with reference to FIG.

In the block on the 5th day of FIG. 4, the operation timer of the control unit 5 is timed up, and the air amount ratio at that time is 100% or less. At the same time that the unit 15 starts operating, the compressor unit 1 of the base load machine that was operating
6 is stopped when a stop signal is input from the control unit 5 to the control unit 6.

At this time, the base load machine and the backup machine are exchanged, the operation timer is initialized to 0, the integration is started again, the compressor unit 15 controls the capacity, and the compressor unit 16 maintains the stopped state. To do.

Next, the time X1 in FIG. 4 will be described with reference to FIG. The time X1 of FIG. 4 and the time X1 of FIG. 5 are the same. When the time X1 when the used air amount ratio exceeds 100% is entered, the rotation speed of the compressor unit 15 becomes the maximum rotation speed, and the power consumption ratio becomes 100%.

The pressure in the air tank 1 is set to the compressor unit 15,
From the control pressure setting of 0.67 MPa to the return pressure setting of 0.65 MPa, the control unit 5 inputs an operation signal to the control unit 6 at this point, and the compressor unit 16 starts operation. At this point, the control unit 5 performs control to fix the rotation speed of the compressor unit 15 to the maximum rotation speed,
The compressor unit 16 controls the capacity. The compressor unit 16 keeps the pressure in the air tank 1 constant by changing the number of rotations according to the change in the used air amount ratio.

When the air usage ratio falls to 100%, the rotation speed of the compressor unit 16 drops to the minimum rotation speed. When the used air amount ratio becomes 100% or less, the pressure in the air tank 1 rises to reach 0.69 MPa, which is the I-type unloading start pressure of the compressor units 15 and 16, at which time the compressor unit 16 becomes I. 3 minutes before the pressure in the air tank 1 drops to 0.67 MPa, the control unit 5 inputs a stop signal to the control unit 6 to stop the compressor unit 16 and stop the compressor unit 16 at the same time. 1
5 is switched to rotation speed control.

Next, the time X2 in FIG. 4 will be described with reference to FIG. The time X2 in FIG. 4 and the time X2 in FIG. 5 are the same. At the time when the time X1 when the used air amount ratio exceeds 100% is entered, the rotation speed of the compressor unit 16 becomes the maximum rotation speed and the power consumption ratio becomes 100%.

The pressure in the air tank 1 is set to the compressor units 15, 1
The control pressure of 0.67 MPa, which is the control pressure setting of No. 6, is reduced to 0.65 MPa, which is the return pressure setting.
Inputs a rotation speed fixed signal to the control unit 6, and the rotation speed of the compressor unit 16 is fixed to the maximum rotation speed for control. At this point, the control unit 5 operates the compressor unit 15 and 15 controls the capacity. The compressor unit 15 keeps the pressure of the air tank 1 constant by changing the number of rotations according to the change of the used air amount ratio.

When the air usage ratio drops to 100%, the rotation speed of the compressor unit 15 drops to the minimum rotation speed. When the used air amount ratio becomes 100% or less, the pressure in the air tank 1 rises to reach the formula I unloading start pressure of the compressor units 15, 16 of 0.69 MPa, at which time the compressor unit 15 becomes I. 3 minutes before the pressure in the air tank 1 drops to 0.67 MPa, the control unit 5 inputs a fixed rotation speed signal to the control unit 6 to control the rotation speed of the compressor unit 16 before the pressure is unloaded. At the same time as switching, the compressor unit 15 is automatically stopped.

In the present embodiment, the operation timer of the control unit 5 is set to one day intervals, but it has a function of adjusting the integration time. In addition, the base load machine is stopped and the backup machine is operated at the same time, and is replaced, but when the operation of the base load machine and the backup machine overlap, at the same time, when they do not overlap, etc. The control unit 5 has a function that can be performed.

As described above, according to the embodiment of the present invention, the control unit for externally operating the base load machine such as the start, stop and rotation of the backup machine and receiving the failure status of the backup machine. By installing or changing at least one such base load machine, most recent compressors are equipped with a control unit that can be operated externally. Not only does it achieve the same level of power saving and operating time as manufacturing equipment, but it can also achieve maximum power saving by combining multiple compressors.

[0114]

According to the present invention, the conventional unit number control device can be omitted by adding or changing at least one variable speed compressor for externally operating another constant speed or variable speed compressor. The cost and installation space required for the air manufacturing system can be minimized, the system pressure control width can be minimized, power consumption can be minimized, and operating time can be leveled.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a compressed air manufacturing system of the present invention.

FIG. 2 is a control time chart showing an operating state in the first embodiment of the present invention.

FIG. 3 is a control time chart showing an operating state according to the second embodiment of the present invention.

FIG. 4 is a control time chart showing an operation schedule in the third embodiment of the present invention.

FIG. 5 is a control time chart showing an operating state in the third embodiment of the present invention.

[Explanation of symbols] 1 air tank 2, 3, 4 pressure sensor 5, 6 Control unit 7, 8 compressor 9,10 Check valve 11, 12, 13, 14 Discharge air pipe 15, 16 Compressor unit 17 Run / stop signal 18 Driving Answer / Failure Signal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukazu Aoki             Hitachi, Ltd. 390 Muramatsu, Shimizu City, Shizuoka Prefecture             Factory Industrial Equipment Group F-term (reference) 3H045 AA06 AA09 AA16 AA25 BA22                       BA32 CA04 DA01 DA32 DA37                       EA13 EA34

Claims (8)

[Claims] 1. A base load machine consisting of one variable speed air compressor, and start and stop by the base load machine.
And a compressed air manufacturing system including at least one backup machine composed of a constant speed or variable speed air compressor whose rotation speed is controlled. 2. The base load machine adjusts the number of operating air compressors and the discharge air amount of the entire system while detecting the pressure of the entire compressed air discharged from the base load machine and the backup machine. The compressed air manufacturing system according to claim 1, which is characterized in that. 3. The base load machine inputs a failure signal from the backup machine, and adjusts the number of operating compressors and the discharge air amount of the entire system in a state where the failed backup machine is removed. The compressed air manufacturing system according to claim 1 or 2. 4. The base load machine has a function capable of being automatically stopped under the condition that all the backup machines are stopped, and the backup machine has a function of not automatically stopping except for a manual operation or a failure. Claim 1 characterized by
The compressed air manufacturing system according to any one of claims 1 to 3. 5. The control of the discharge air pressure of the entire system by setting the difference between the maximum discharge air amount and the minimum discharge air amount, which is the rotation speed control range of the base load machine, to be equal to or greater than the specification discharge air amount of the backup machine The compressed air manufacturing system according to any one of claims 1 to 4, wherein the compressed air manufacturing system has a narrow width. 6. A base load machine comprising a variable speed air compressor and at least one backup machine comprising a constant speed or variable speed air compressor, wherein the base load machine comprises the backup. With a control unit for controlling the operation of the machine, the backup machine,
A compressed air manufacturing system comprising a control unit for controlling the operation of the backup machine itself under the control of the base load machine, the pressure detecting the pressure of the discharge air of each of the base load machine and the backup machine. The base load machine control unit includes a detection unit and a pressure detection unit that detects the pressure of the discharge air of the entire system. A compressed air manufacturing system characterized by adjusting the number of compressors in operation and the amount of discharged air by fixing the speed to the maximum speed. 7. The control unit of the base load machine has a function of inputting a failure signal from the backup machine, and the control unit of the backup machine sends a failure signal of the backup machine itself to the base load machine. The compressed air manufacturing system according to claim 6, which has a function of outputting to a control unit. 8. The compressed air manufacturing system according to claim 6, wherein the backup machine is stopped only by a manual or stop signal from the base load machine except when the backup machine is out of order. system.