JPH0413439Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a surging prevention device for a turbo compressor used as a power air source in a general factory to prevent the turbo compressor from surging during momentary power failure. It is.

[Prior Art] Conventionally, the turbo compressor 1 compresses the air taken in from the absorption filter silencer 2 and discharges it from the discharge valve 4 via the receiver 3, as shown in FIG. A suction control valve 6 is provided on the upstream side of the compressor 1, and a discharge branch pipe 7 is provided on the downstream side of the compressor 1. A blow-off control valve 8 is provided, and the suction control valve 6 and the blow-off control valve 8 are connected to an overload controller of the electric motor (not shown), and the air discharge control valve 8 is connected to an overload controller of the electric motor, which is used to prevent problems caused by excessive air usage, changes in intake air conditions, etc. This is designed to prevent the motor from overloading. Further, each control system of the suction control valve 6 and the air discharge control valve 8 is provided with three-way valves 9 and 10, and a pressure switch connected to the receiver 3 is provided.
Each of them is controlled by a signal from the PS. 11 is a check valve.

In the operation of the conventional turbo compressor described above, fluctuations in the amount of air used are sensed, and load and no-load operations are repeated between two preset pressure points.

[Problem that the invention aims to solve] However, due to a power outage, the problem occurred momentarily (0.01 to 0.1 seconds).
When the compressor 1 stops, the rotational speed decreases and the centrifugal force disappears, so the head decreases and surging occurs. This means that in the relationship between pressure P and air volume Q shown in Figure 3, when an instantaneous power failure occurs at the operating point at point A on the performance curve, the performance curve shifts to point B.
This is because the point moves beyond the surging line and enters the surging range.

Conventionally, when surging occurs during an instantaneous power failure as described above, the compressor 1 is placed under no load, the power is turned off, and the compressor operation is stopped.

However, once the compressor 1 stops operating when a momentary power outage occurs, it conventionally takes about 45 to 50 seconds from the moment the momentary power outage occurs to restart the compressor and apply load.
During that time, compressed air was stopped, so an air accumulator with a large capacity was required.

Therefore, in order to significantly shorten the time from when a momentary power failure occurs to when operation can be resumed, the present invention is designed to move the operating point to point C on the performance curve when surging occurs in Figure 3. This is intended to avoid surging even if the rotational speed of the compressor decreases when the compressor is stopped.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention reduces the discharge pressure of the compressor by releasing air downstream of the compressor during a power outage to the downstream side of the turbo compressor. A dedicated air blowing valve is connected to the system, and the signal line is connected to the control system of the dedicated air blowing valve so that the dedicated air blowing valve is opened by a signal that is issued only during a power outage.

[Function] A dedicated control valve connected to the downstream side of the compressor opens during a power outage to lower the compressor discharge pressure, so the operating point where surging would normally occur during a momentary power outage has been reduced to the performance shown in Figure 3. Move to point C on the curve, move away from the surging range, and avoid entering surging. As a result, surging can be prevented while the compressor remains under load and the motor is not stopped.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIG. 1, a third
CV that satisfies the pressure P and air volume Q at point C shown in the diagram
An air supply line 1 which is a control system that connects a dedicated air blowing valve 12 having a value and opens and closes the dedicated air blowing valve 12.
3 is provided with a three-way valve 14, and the signal line is connected to the three-way valve so that switching of the three-way valve 14 is performed by an instantaneous power failure signal 15 issued at the time of a power outage.
When the air in the air supply line is released through the three-way valve 14 by switching, the dedicated blow-off valve 12 opens and the discharge pressure of the compressor 1 is lowered.

Components other than those shown in FIG. 1 are the same as those shown in FIG. 2.

Even a momentary power outage (0.01 to 0.1 seconds) will cause the rotation speed of compressor 1 to drop, and as shown in Figure 3, if a momentary power outage occurs at operating point A, the operating point will shift to B and enter surging. .

In the present invention, when a momentary power failure occurs, the momentary power failure signal 15 is issued and the three-way valve 14 is switched to release the air in the air supply line 13 to the atmosphere, so the dedicated blow-off valve 12 opens, which causes the discharge pressure of the compressor 1 to Since the pressure is lowered, the operating point moves to C along the performance curve in FIG. 3, preventing entry into the surging range and allowing operation at a constant pressure. When the power outage is resolved and electricity is restored, the instantaneous power outage signal disappears, the three-way valve 14 is switched to its original state, the dedicated blow-off valve 12 is closed by air pressure, and the operating point becomes point A in Figure 3. be returned.

In the above operation, the suction control valve 6 remains open, the blowout control valve 8 remains closed, the compressor 1 remains under load, and the dedicated blowoff valve 12 is opened only in the event of a momentary power failure without stopping the motor. When the compressor 1 is opened, the operating point is moved from point A to point C as the rotational speed of the compressor 1 decreases.

[Effects of the invention] As described above, according to the surging prevention device for a turbo compressor of the present invention, a special blow-off valve is provided that automatically opens in response to a signal only in the event of a momentary power outage to lower the discharge pressure of the compressor. This configuration prevents surging during instantaneous power outages, allowing the compressor to maintain its load and operate without stopping the motor. Conventionally, it took 45 to 50 seconds to recover from a momentary power outage It can be reduced to 5 to 10 seconds. This provides an excellent effect in that the time during which the compressed air is stopped is short and the volume of the air accumulator can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is a schematic diagram showing a control system of a conventional turbo compressor,
FIG. 3 is a diagram showing the relationship between the pressure and air volume of the turbo compressor. 1 is a compressor, 12 is a dedicated blow-off valve, 14 is a three-way valve, and 15 is an instantaneous stop signal.

Claims (1)

[Scope of utility model registration request] A dedicated blow-off valve is connected to the downstream side of the turbo compressor to release the air downstream of the compressor and reduce the discharge pressure of the compressor in the event of a power outage, and the dedicated blow-off valve is connected to a signal that is issued only during a power outage. A surging prevention device for a turbo compressor, characterized in that the signal line is connected to a control system of the dedicated blow-off valve so as to open the blow-off valve.