JPS5963397A - Control device for turbo compressor - Google Patents

Abstract

PURPOSE:To elongate change-over cycle of load running-noload running by fixing an intake valve to the minimum allowable flow condition in the load running and to the fully opened condition in noload condition. CONSTITUTION:When one of turbo compressors is run under the noload condition in the noload control section 15 on the basis of signals from a pressure detecting section 11, commands from the noload control section 15 act on a throttle amount control section 14 to fix the throttle of intake valves 2 of the remaining turbo compressors to the fully opened condition. On the other hand, when all turbo compressors are run by a load control section 16 under the load condition on the basis of signals from the pressure detecting section 11, commands from the load control section 16 act on the throttle amount control section 14 to fix the intake valves 2 of all turbo compressors to the minimum allowable flow condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a tarp compressor, and particularly to energy-saving operation control when a plurality of tarp compressors are installed.

[Technical background of the invention]

Generally, a piping system of an air supply facility that supplies compressed air to a load device is configured as shown in FIG. That is, air flowing into the turbo compressor 3 from the suction port 1 via the suction valve 2 is compressed by the turbo compressor 3 and then supplied to the header 5 via the check valve 4. Compressed air is supplied from the header 5 to a load device (not shown) in each factory through each air supply pipe 6.

When the capacity of the tarp compressor is larger than the load capacity, an operation is performed in which compressed air is blown while keeping the air pressure in the header 5 within a predetermined allowable range while repeatedly opening and closing the suction valve 2. control, that is, load-no-load control.

Note that, as is well known, in a turbo compressor, if the difference between the suction side air pressure and the discharge side air pressure is too large, a surzander phenomenon will occur due to air vibrations, and there is a risk that the turbo compressor will be damaged. Therefore, when carrying out the load-no-load control operation as described above, the tar is provided with the blowoff valve 7 on the discharge side of the compressor 3, and the moment when the suction valve 2 is fully closed, that is, from the load operation. By opening the blow-off valve 7 at the moment of switching to no-load operation, the air pressure on the discharge side of the compressor 3 is lowered.

A control device for a turbo compressor that supplies compressed air to a load device using a plurality of turbo compressors that perform such a load-no-load operation is configured as shown in FIG.

In other words, numeral 11 in the figure is a pressure detection unit υ that detects the air pressure inside the header 5, and the pressure difference between the air pressure detected by this pressure detection unit 11 and the set air pressure determined corresponding to the load capacity is the pressure. It is calculated by the difference calculating section 12. Then, the discharge amount calculation unit 13 calculates the discharge agent of the turbo compressor 3 according to the pressure difference calculated by the pressure difference calculation unit 12, and the compression agent to be discharged from the tarp compressor 3 is The throttling amount of the suction valve 2 is set so that the air is discharged at the above-mentioned amount. On the other hand, if the pressure difference calculated by the pressure difference calculating section 12 exceeds a preset allowable range, the no-load control section 15 or the load control section 16 throttles down the no-load operation or the loaded operation. When a command is given to the υ amount control section 14, the aperture amount control section 14
The suction valve 2 is fully closed or opened and no-load operation or loaded operation is started.

Next, the movement of each component of the control device having such a configuration during load operation and no-load operation will be explained using a specific example. Now, suppose a load device with a load capacity of 140 has a rated capacity of 1
Assume that two tarp compressors A and B of 00 are connected in parallel to supply compressed air. However, in order to prevent the occurrence of the above-mentioned over-knocking phenomenon, in the turbo press machine, the throttle range of the suction valve 2 is limited to a range of 100 to 80 of the rated capacity.

When the air pressure in the header 5 interposed between the turbo compressors A and B and the load device decreases and reaches the lower limit of the allowable range shown in FIG. In response to the command, each suction valve 2 of the turbo compressors A and B is fully opened by the throttle υ amount control unit 14 to 100%.
n is operated under load with a rated capacity of lOO. As shown in Fig. 4, when turbo compressors A and B each start load operation with a rated capacity of 100, the load capacity is 140, so there is fi600 exponent air per unit time inside the header 5. Accumulated. Therefore, the air pressure within the header 5 increases at a constant rate. When the air pressure reaches the set air pressure at time t1 and further increases, the throttle amount of each suction valve 2 is controlled via the discharge amount calculation section 13 according to the pressure difference from the pressure difference calculation section 12. The air is narrowed down in the section 14, and the amount of air flowing into the header 5 is reduced. However, as mentioned above, the maximum throttle limit of the suction valve 2 is the rated value of 80, so
Even if the turbo compressors A and B are each operated at a capacity of 80, the difference with the load capacity of 140, that is, the air pressure in the header 5 is increased by 20 per hour.
I'm going to get even higher game 1. When the air pressure reaches the upper limit of the allowable range at time t, the no-load control section 15 instructs the throttling control section 14 to control one of the turbo compressors.
For example, when the suction valve 2 of turbo compressor A is closed, Compressor A is switched from load operation to no-load operation. When the turbo compressor 1a A starts no-load operation, air is supplied into the header 5 only by the turbo compressor 4KJ B, which is operating under load at a capacity of 80, resulting in an air shortage of 960 per unit time. Therefore, the air pressure within the header 5 decreases. The above air pressure is at time t3
When the air pressure reaches the set air pressure and further decreases, the throttle 9 of the suction valve 2 of the turbo compressor B is opened, contrary to the above, and the amount of air flowing into the hesodor 5 increases. However, since the rated capacity of tarp compressor B is 100, the
An air deficit of 0 remains, as a result of which the air pressure in the header 5 further decreases.

When the air pressure reaches the lower limit of the allowable range at time t,
Turbo compression i3A, B according to a command from the load control unit 16
start load operation at a rated capacity of 100, respectively.

In this way, ter y3? Compressor A has a constant cycle To-(
By repeating load operation and no-load operation at t, = to), the air pressure in the header 5 is kept within the specified range.

[Problems with background technology]

However, the conventional turbo compressor control device configured as described above has the following problems.

That is, as described above, in the turbo compressor, the blowoff valve 7 is opened when switching from load operation to no-load operation in order to prevent the occurrence of surging. In the above example, at time t, tyl? Compressor A is being switched from load operation to no-load operation. Opening the blow-off valve 7 during this switching and releasing a large amount of compressed air in the turbo compressor A into the atmosphere will result in a large amount of energy loss for the entire air supply equipment, resulting in the operation of the equipment. There is a risk that costs will increase.

Therefore, the development of a control device for a tarp compressor that can reduce air loss due to compressed air discharge has been awaited. However, it is an object of the present invention to provide a control device for a tarp compressor that can reduce air loss by reducing the number of times of switching between load operation and no-load operation, thereby reducing operating costs of the entire air supply equipment. It is in.

[Summary of the invention]

In order to achieve the above object, the turbo compressor control device of the present invention is characterized by being configured as follows.

In other words, the pressure difference calculation unit calculates the pressure difference between the header tank pressure from the pressure detection unit and the set pressure by 3゛), and when this pressure difference is a positive value and exceeds the allowable range, no-load control is performed. During the no-load operation period, the interlock section closes the suction valves of some of the tarp compressors to start no-load operation, and during the no-load operation period, the interlock section closes the suction valves of some of the tarp compressors to start no-load operation. Fix the suction valve throttle in the fully open position. - When the pressure difference is a negative value and falls below the allowable range, the load control section opens the suction valves of all tarp compressors to start load operation, and during the load operation period, the interlock The throttles of the suction valves of all turbo compressors are fixed at the minimum allowable flow state.

[Embodiments of the invention]

FIG. 5 is a block diagram of a control device for a turbo compressor according to an embodiment of the present invention, and the same parts as in FIG. 2 are given the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

In this embodiment, an interlock section 17 is installed, which is connected to the no-load control section 15, the load control section 16, and the aperture amount control section 14 through signal lines, and operates as follows.
In other words, the no-load control section 1 is operated based on the signal from the pressure detection section 11 during a period in which some of the turbo compressors are operated under no-load.
5 acts on the throttle amount control section 14 to fix the throttles 9 of the suction valves 2 of the remaining turbo compressors in a fully open state.

On the other hand, based on the signal from the pressure detection section 11, the load control section 1
During the period in which all the turbo compressors are operated under load at step 6, the throttling amount control section 1 is
4 to fix the suction valves 2 of all turbo compressors to the minimum flow state.

Next, the movement of each component during load operation and no-load operation of the control device configured as described above will be explained using the above-mentioned specific example.

First, the air pressure of the header 5 interposed between the tarp compressors A and B and the load device decreases at time t. When the lower limit of the allowable range shown in FIG. 6 is reached, the tarp compressor A, B
Each suction valve 2 is opened, but the throttle position of each suction valve 2 is set to the minimum permissible flow state by the command from the interlock unit 17, that is, the throttle position of each suction valve 2 is set to the turbo compressor A.

B are fixed to have an operating capacity of 80 each. 7th
As shown by the solid line in the figure, when compressors A and B start operating with a capacity of 80 each, the load capacity is 140, so 20 residual air is accumulated per unit time inside the header 5. Ru.

Therefore, the air pressure within the header 5 increases as shown by the solid line in FIG. During the period in which the air pressure reaches the set air pressure at time t11 and further reaches the upper limit of the allowable range at time t□, the throttle value of the suction valve 2 is not changed. When the air pressure reaches the upper limit value, the suction valve 2 of the tarp compressor A is closed by the throttle amount control section 14 in response to a command from the no-load control section 15, and the tarp compressor A changes from load operation to no-load operation. Switched to driving. On the other hand, the throttle υ of the suction valve 2 of the turbo compressor B, which continues to operate under load, is fixed to the fully open state by a command from the interlock section 17. Turbo compressor A
When starts no-load operation at υ0, air is supplied into the header 5 only by turbo compressor B, which is operated under load at a rated capacity of 100 441 seconds, so per unit time, ! 1,1
40 air shortage occurs, and the air pressure in the header 5 decreases. During the period in which the air pressure reaches the set air pressure at time t13 and further reaches the lower limit value of the FF volume fli1 at time t14, the throttle value of the suction valve 2 of the turbo pressure piglet B is not changed. When the air pressure reaches the lower limit of the allowable range at time t14, the tarp compressor A + B starts load operation in response to a command from the load control section 16. Therefore, the total period T1 is 'r, = (t14 tlo)
becomes.

Note that the dotted lines in FIGS. 6 and 7 indicate the air pressure in the header 5 and the throttle opening degree of the suction valve 2 in the conventional control device, respectively.

In this way, in the control device of this embodiment, the amount of residual air during the load operation period of tarp compressors A and B until the air pressure reaches the set value from the lower limit value is 2o. , the residual air amount can be reduced to 1/3 compared to 60 in the conventional control device. Therefore, the time required to reach the set value from the lower limit value (t
o too) can be extended to three times the conventional required time (tIto).

On the other hand, the air shortage per unit time during the no-load operation period of turbo compressor A until the air pressure reaches the set value from the upper limit value is 4o, compared to 60 for the conventional control device. The above air shortage can be reduced by 2/3. Therefore, the time required to reach the set value from the above upper limit value (t13 t1□) is compared with the conventional time required (
ts tz).

Therefore, the cycle of load operation - no-load operation 'r, =
(t14-tlo) is the conventional period T. = (number - t
o) Since the length can be increased, it is possible to reduce the air loss that occurs when switching between load operation and no-load operation while the control device is in operation for a certain period of time. As a result, operating costs for the entire air supply facility can be reduced.

In the embodiment, if the pressure difference calculated by the pressure difference calculation unit 12 is within the allowable range from the beginning, the tarp pressure 14 is adjusted according to the pressure difference as explained in the conventional control device.
A discharge amount calculation unit 13 calculates the discharge amount of the machine. Further, the throttling f) fai control unit 14 sets the throttling amount of the suction valve 2 so that the compressed air discharged from the turbo compressor has the above discharge amount.

By controlling as described above, it is also possible to connect load devices with various load capacities.

〔Effect of the invention〕

As described above, according to the present invention, during load operation, the suction valve of the tarp compressor is fixed in the minimum allowable flow state, so that the rate of increase in pressure in the header tank can be suppressed. On the other hand, during no-load operation, the suction valves of some of the tarp compressors operating under load are fixed in a fully open state, so the rate of decrease in pressure in the header tank can be suppressed.

Therefore, the switching cycle between load operation and no-load operation can be extended, so that the amount of air used for switching can be reduced, and the operating cost of the entire air supply equipment can be reduced.

[Brief explanation of drawings]

Figure 1 is a piping system diagram of the air supply equipment, Figure 2 is a block diagram of a conventional tarp compressor control device, Figure 0 is an air pressure characteristic diagram showing the characteristics of the control device, and Figure 4 is the same. FIG. 5 is a block configuration diagram of a control device for a Coude compressor according to an embodiment of the present invention; FIG.
The figure is an air pressure characteristic diagram showing the characteristics of the control device, and FIG. 7 is an operation explanatory diagram showing the operation of the control device. DESCRIPTION OF SYMBOLS 1... Suction port, 2... Suction valve, 3... Turbo compressor, 5... Header, 7... Air discharge valve, 11... Pressure detection part, 12... Pressure difference Calculation section, 13... Discharge amount calculation section, 14... Restriction υ amount control section, 15... No-load control section, 16... Load control section, 17... Interlock section. Figure 1 Figure 2 -599- Questions Figure 5 Figure 6 @ Time Figure 7 Questions

Claims (1)

[Claims] A plurality of tarp compressors are connected in parallel to a header tank that communicates with the load, and a predetermined pressure is detected by a gas force detection unit provided in each of these turbo compressors and connected to each of the tarp compressors. A pressure difference calculation unit that calculates the pressure difference from the set pressure, and when the pressure difference is a positive value and exceeds an allowable range, some turbo compressors close their suction valves and start no-load operation. a no-load control section; a load control section that opens the suction valves of all tarp compressors to start load operation when the pressure difference is a negative value and falls below the above-mentioned allowable range; An interlock unit that fixes the throttles of the suction valves of the remaining tarp compressors whose valves are not blocked in the fully open state, and also fixes the throttles of the suction valves of all turbo compressors in the minimum allowable flow state during the load operation period. A control device for a tarp compressor, comprising: