JPH07189986A - Surging preventive control device for turbo pneumatic machine - Google Patents

Abstract

PURPOSE:To provide a surging preventive control device for a turbo pneumatic machine simple, low-priced and capable of avoiding the generation of surging automatically without time delay only by detecting pressure and capable of swiftly escaping from a surging area even in case of running into surging. CONSTITUTION:A surging preventive control device for a turbo pneumatic machine has a pressure transmitter 1 for detecting air pressure on the discharge side of a pneumatic machine and converting it into an electric signal, a band- pass filter 2 for passing only a specific band signal out of the signals outputted from the transmitter 1, a comparator 3 for comparing a reference signal with the output signal of the band-pass filter and generating a trigger pulse, an avoidance computing element 4a outputting a control signal for opening an exhaust valve 6, disposed on the discharge side of the pneumatic machine, stepwise by the pulse outputted from the comparator 3, and an escape computing element 4b outputting a control signal for fully opening the exhaust valve 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device which is applied to a turbo-type air machine and which avoids the occurrence of surging and escapes from the surging area when surging occurs.

[0002]

2. Description of the Related Art When surging occurs during operation of a turbo-type blower or compressor, the air volume and pressure change periodically,
Along with this, the airframe and the valves and pipes connected to it also vibrate, and the operating status becomes unstable, making it impossible to continue operation. Conventionally, as a measure against surging, the discharge air volume and the wind pressure are measured, the region where it is predicted that surging will occur is estimated from empirical values, and the control method that avoids the occurrence of surging by opening the blow-off valve is available. Was adopted.

[0003]

However, the above-mentioned prior art means for avoiding / leaving surging has the following problems. Estimating the surging area based on empirical values could not be an accurate prediction because it is related to the installation environment and operating conditions of the air machinery. Further, since the occurrence of surging is determined by the vibration of the machine body and the rotating shaft, the temperature of the intake air and the discharge air, there is a time delay from the occurrence of surging to the determination.

The object of the present invention is to solve the above-mentioned problems and to generate a minute pressure fluctuation in the vicinity of surging, and to generate a large pressure fluctuation in surging. The purpose of the present invention is to provide a simple and inexpensive control device that can avoid the occurrence of surging without a time delay and can quickly escape from the surging area even when entering the surging.

[0005]

A surging prevention control apparatus for a turbo-type air machine according to a first aspect of the present invention includes a pressure transmitter 1 for detecting a discharge pressure, converting it into an electric signal, amplifying and outputting the electric signal, and a pressure transmitter 1 for the pressure transmitter. Of the output signals, the bandpass filter 2 that passes only the signal of the set frequency band is compared with the reference signal set corresponding to the pressure fluctuation level and the output signal of the bandpass filter, and the judgment result is output as a trigger pulse. And a surging avoidance computing unit 4a that sequentially outputs a stepwise opening increase / decrease signal to the blowoff valve 6 by a trigger pulse output from the comparator. To do.

In the surging prevention control apparatus for the turbo-type air machine of the second invention, the blow-off valve 6 is fully opened by the trigger pulse output from the comparator 3 by the electric signal of the large fluctuating pressure of the specific frequency detected when the surging occurs. In addition to having a surging escape computing unit 4b for outputting a control signal for controlling, the configuration is the same as the preventive control device of the first invention.

[0007]

The operation of the first and second inventions having the above-mentioned construction will be described. The fluctuating pressure due to surging is detected by a pressure detecting hole formed in the machine body or a pressure converter attached to a pressure guiding pipe connected to the detecting hole and converted into an electric signal. The electric signal is amplified by the amplifier circuit of the pressure transmitter to a level suitable for signal processing and output. The signal output from the pressure oscillator contains a frequency component that is not related to surging, but it is attenuated by a band filter and only the signal in the frequency band near surging / surging is passed and output to the comparator. To do. The comparator sets the output level of the reference signal generation circuit corresponding to the level of pressure fluctuation, and compares the set reference signal with the signal output from the bandpass filter. When the output signal of the bandpass filter is determined to be at a higher level than the set reference signal, a trigger pulse to be output to the arithmetic unit is generated.

Even if a signal other than Sirzink is captured as a pulse, the arithmetic unit does not input a trigger pulse three or more times within a specified time of, for example, 10 seconds by utilizing the repeating characteristic during surging. As long as the control signal is not output to the blowoff valve, it is possible to perform control limited to surging. The signal in the vicinity of surging and the signal at the time of surging can be distinguished by the output setting level of the reference signal in the comparator. This is because the signal level of the pressure fluctuation corresponding to the level of the reference signal is small in the vicinity of surging and is large in the case of serge inrush.

[0009]

FIG. 1 shows a system configuration diagram of a surging prevention control device for a centrifugal compressor according to an embodiment of the first and second inventions. The configuration and operation will be described with reference to FIG. The centrifugal compressor compresses the gas in the vortex chamber 20 by the rotation of the impeller 10 and increases its pressure. When the pressure ratio reaches the upper limit, surging occurs, causing vibrations in the airframe and the valves and pipes connected to it, which makes the operating condition unstable. Vortex room 2
The pressure transducer 1a is attached to the pressure detection hole formed at 0 to detect the pressure at the outlet of the vortex chamber and convert it into an electric signal. This electric signal is amplified by the amplifier circuit of the pressure transmitter 1 to a level suitable for signal processing and output. At that time, a pressure fluctuation B of 0.5 to 20 Hz is measured. In the vicinity of surging,
A small pressure fluctuation A occurs in the almost same frequency band as compared with the time of surging.

Although the fluctuating pressure signal output from the pressure transmitter 1 includes a frequency component that is not related to surging, it is attenuated by the bandpass filter 2 and only the vicinity of surging / the frequency band at surging is surpassed. It is passed and output to the comparator 3. In the comparator 3, the output level of the built-in reference signal generation circuit is set so as to correspond to the level of the fluctuating pressure signal input from the bandpass filter 2,
Compare the reference signal and the fluctuating pressure signal. When it is determined that the fluctuating pressure signal is at a higher level than the reference signal, a trigger pulse is generated, and the output destination is classified as the avoidance calculator 4a or the escape calculator 4b according to the set level of the reference signal, and the trigger pulse is output. To do.

FIG. 2 shows a flowchart of signal processing in the surging avoidance computing unit 4a shown in FIG. The trigger pulse generated by the comparator 3 has a specified time (for example, 10
If it is input to the surging avoidance computing unit 4a more than a specified number of times (for example, 3 times) within seconds, it can be determined that the signal is a pressure fluctuation signal in the vicinity of surging. 5%) open. When the pressure fluctuation is detected thereafter, the further valve opening is opened from the opening at that time by the specified opening, and the discharge pressure is reduced to avoid the occurrence of surging.

Further, in the situation where the blow-off valve 6 is opened and the surging prevention is functioning, when the pressure fluctuation is not detected for a specified time (for example, 30 seconds) or more, the opening at that time is changed to the specified opening ( For example, 2%) The blowoff valve 6 is closed. When the operating range of the centrifugal compressor is out of the vicinity of surging and there is no pressure fluctuation, the blowoff valve 6 is in a fully closed state.

Next, the surging escape calculator 4 in FIG.
FIG. 3 shows a flowchart of the signal processing in step b. Figure 1
At, the output level of the reference signal of the comparator 3 is
Set so as to correspond to the level of the fluctuating pressure signal at the time of surging, and compare the fluctuating pressure signal with the reference signal.
It is determined and a trigger pulse is output to the surging escape calculator 4b. When the trigger pulse is input to the arithmetic unit more than a specified number of times (eg, 3 times) within a specified time (eg, 10 seconds), it is determined that surging has occurred, and the circuit switch 5 switches from the control signal line to the fully open signal line. To be By this circuit switching, the blow-off valve 6 is fully opened, the discharge pressure of the compressor is lowered, and escape from surging.

In the embodiment shown in FIG. 1, the blow-off valve 6 is an electromagnetic control valve and the signal line to the blow-off valve is switched by the circuit switching device 5. However, the blow-off valve is an air pressure control valve and the electromagnetic control valve is used. A system in which the control air flow path leading to the blow-off valve is switched by a directional control valve is also applicable.

[0015]

EFFECTS OF THE INVENTION In a fluid machine in which a surging phenomenon occurs, it is possible to avoid the occurrence of surging automatically and without a time delay only by detecting a fluctuating pressure, and to quickly escape from the surging area even if a surge occurs. You can

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a surging prevention control device for a centrifugal compressor according to an embodiment of the first invention and the second invention.

FIG. 2 is a flowchart of signal processing in a surging avoidance computing unit 4a in FIG.

FIG. 3 is a flowchart of signal processing in a surging escape calculator 4b in FIG.

[Explanation of symbols]

1 ... Pressure transmitter, 1b ... Pressure converter, 2 ... Bandpass filter, 3 ... Comparator, 4a ... Surging avoidance calculator,
4b ... Surging escape calculator, 5 ... Circuit changer, 6 ... Blowoff valve, 10 ... Impeller, 20 ... Swirl chamber.

Claims (2)

[Claims] 1. In a turbo-type air machine, a pressure transmitter (1) for detecting fluctuation pressure on the discharge side and converting it into an electric signal.
A bandpass filter (2) for passing only a signal in the frequency band near surging or at the time of occurrence of the signal output from the pressure transmitter; a reference signal corresponding to the level of fluctuating pressure; and a bandpass filter output from the bandpass filter. Compare the signals
A comparator (3) that generates a control pulse when the level of the output signal from the bandpass filter is high, and a blower valve (6) by a trigger pulse output from the comparator (3)
And a surging avoidance computing unit (4a) for outputting a control signal for opening / closing the valve in a stepwise manner. 2. A blow-off valve (6) by a trigger pulse output from a comparator (3) by an electric signal of a large fluctuating pressure of a specific frequency detected when surging occurs.
The surging prevention control device for a turbo air machine according to claim 1, further comprising a surging escape calculator (4b) for outputting a control signal for fully opening.