JPH09133093A - Fluid machine and its operation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable action by quickly and accurately detecting a fluctuation of an operating condition generated by a flow amount smaller the a flow amount in a design point of a fluid machine. SOLUTION: In a fluid machine having an inlet guide vane 6 and an impeller 2, based on a data obtained during operation of this fluid machine, an index value representing a degree of flow stability in the impeller 2 is calculated, an opening of the inlet guide vane 6 of the fluid machine and a rotational speed of the impeller 2 are controlled so that this index value comes to be in a prescribed range, and a delivery and a head obtain a value required for the fluid machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid machine such as a centrifugal and mixed flow type fluid pump, a blower for gas and a compressor, and more particularly to a fluid machine with an inlet guide vane and a diffuser vane.

[0002]

2. Description of the Related Art When a centrifugal or oblique flow pump is operated at a flow rate lower than the design point, flow separation occurs in the impeller, diffuser, etc., which triggers surging to cause large self-excited vibration in the entire system. Occur. Conventionally, the methods for detecting surging are pressure, flow rate, temperature,
The surging condition was judged by measuring the time average value of the performance and comparing it with the previously measured value.

Japanese Patent Publication No. 5-53956 and Japanese Unexamined Patent Publication No. 62-11 disclose that surging is performed by detecting a rapid temperature rise.
3889, JP-A-59-77089, JP-A-59-
79097 and JP-A-56-2496. In addition, Japanese Patent Laid-Open No. 63-16 discloses that the detection is performed by increasing the pressure.
1362, JP-A-58-57098, JP-A-55-
No. 114896 and the like, which is performed by the differential pressure between the diffuser of the hub and the shroud.
And Japanese Patent Laid-Open No. 62-51794 for detecting the pressure difference between the pressure surface and the negative pressure surface of the diffuser blade, and Japanese Patent Laid-Open No. 63-9409 for detecting the pressure waveform.
There is No. 8. Further, Japanese Patent Application Laid-Open No. 57-129297 discloses a method for detecting the rate of change of the pressure coefficient of the blade, Japanese Patent Application Laid-Open No. 4-47197 discloses a method for detecting the differential of shaft vibration, and Japanese Patent Application Laid-Open No. Hei 4-47197 detects a vibration of the shaft with a microphone. 3-2
There is No. 13696.

[0004]

All of the above conventional methods measure the time average value of pressure, temperature, etc.,
This is an indirect method of comparing this with the previously measured value at the time of surging, and it was difficult to detect surging accurately and promptly. This is because even if a surging point was specified by conducting a performance test in advance, the surging point was affected by the volume of the piping system, so a pipe with a different volume from the performance test was used in the actual device. This is because, in this case, accurate detection cannot be performed, and since a time average value of each state value is measured, a certain delay occurs in detection.

In particular, in a pump or the like which generates high pressure, a relatively small fluctuation in the operating condition that does not lead to surging has a great influence on the piping and the like, and it is necessary to detect this early to suppress the fluctuation. However, it is difficult to detect minute fluctuations quickly by the above method.

The present invention has been made in view of the above-mentioned circumstances, and is a fluid capable of promptly and accurately detecting a variation in an operating state which occurs at a flow rate smaller than a design point flow rate of a fluid machine and performing a stable operation. An object of the present invention is to provide a machine operation control method and apparatus.

[0007]

According to a first aspect of the present invention, in a fluid machine having an inlet guide vane and an impeller, the flow stability in the impeller is based on data obtained during the operation of the fluid machine. Calculate the index value showing the degree of sex,
The opening degree of the inlet guide vanes of the fluid machine and the rotation speed of the impeller are controlled so that the index value falls within a predetermined range, and the flow rate and the head reach values required for the fluid machine. Is a method of controlling the operation of a fluid machine.

According to a second aspect of the invention, the index value is
The operation control method for a fluid machine according to claim 1, wherein the ratio is a flow velocity ratio between an inlet and an outlet of the impeller. The invention according to claim 3 is the operation control method for a fluid machine according to claim 1, wherein the index value is a rate of change of a ratio of pressures at an inlet and an outlet of the impeller with respect to a flow rate. .

According to a fourth aspect of the present invention, a discharge adjusting valve for adjusting the discharge amount is provided on the downstream side of the fluid machine, and the opening of the discharge adjusting valve is changed to obtain the rate of change of the pressure ratio with respect to the flow rate. The operation control method for a fluid machine according to claim 3, wherein The invention according to claim 5 further performs control for adjusting the angle of the diffuser blade to an angle that is most stable with respect to the measured flow rate, and operation control of the fluid machine according to claim 1. Is the way.

According to a sixth aspect of the present invention, in a fluid machine having an inlet guide vane with a variable angle and an impeller with a variable rotational speed, a sensor for detecting operation data at a predetermined position of the fluid machine, Based on the value detected by the sensor, calculate an index value that indicates the degree of flow stability in the impeller, and make sure that this index value is within the specified range, and that the flow rate and head are the values required for the fluid machine. It is a fluid machine having a control means for controlling the opening degree of the inlet guide vanes and the rotation speed of the impeller of the fluid machine.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluid machine with variable guide vanes according to the present invention will be described below with reference to FIGS.

1 and 2 are views showing a single-stage centrifugal compressor to which the present invention is applied. FIG. 1 is a longitudinal sectional view thereof, and FIG.
Is a partial side view thereof. The impeller 2 gives kinetic energy to the fluid flowing from the suction pipe 1, sends it to the diffuser 3 to raise the pressure, and sends it from the scroll 4 to the discharge pipe 5.

A plurality of fan-shaped inlet guide vanes 6 are arranged in the suction pipe 1 in the circumferential direction, and an actuator 8 is connected thereto via a transmission mechanism 7. The diffuser vane 3 a is arranged on the diffuser 3 on the downstream side, which is also connected to the actuator 10 via the transmission mechanism 9. The suction pipe 1 is provided with a flow rate sensor 11 for measuring the suction flow rate, and pressure sensors S _{1 to} S ₃ are provided before and after the impeller 2. That is, the sensor S ₁ is at the latter stage of the suction pipe 7, and the sensor S ₂ is at the diffuser 4
Sensors S ₃ are attached to the discharge pipe 9 at the two inlets of. The shaft of the impeller 2 has a rotation speed sensor 12,
The diffuser 6 is provided with a diffuser angle sensor 15, and the inlet guide vane 6 is provided with an inlet guide vane angle sensor 16.

FIG. 3 is a block diagram showing the configuration of the control system of this fluid machine. As shown in this figure, this fluid machine with variable guide vanes is equipped with a processor 21, which, based on the data obtained during the operation of the fluid machine, determines the condition between the inlet and the outlet of the impeller. It has the function of calculating the amount of change in the amount and adjusting the operating conditions of the fluid machine based on this amount of change.

On the input side of the arithmetic processing unit, the pressure sensors S _{1 to} S ₃ , the flow rate sensor 11, the rotation speed sensor 12, the diffuser vane angle sensor 15, the inlet guide vane angle sensor 16 and the required fluid machine are installed. An input device 23 for inputting the operating state and the like is connected, and the inlet guide vane 6 is provided on the output side.
Control drive device 24 for variably controlling the fan, second control drive device 25 for variably controlling the diffuser blade 3a, and impeller 2
Is connected to a third control drive device 26 for controlling the number of revolutions, that is, the number of revolutions of the fluid machine. In addition, the sensors S _{1 to} S ₃
The functions of the amplifier 13, the filter 14, the input interface, the arithmetic processing unit 21 and the like connected to can be performed by one microprocessor.

Below, referring to the flow chart of FIG.
The operation control method of the fluid machine of the present invention will be described. First,
In the initial setting of step 1, the rotation speed of the impeller 2 and the angle of the inlet guide vane 6 are set to appropriate values that do not exceed predetermined limits. Next, in step 2, the processing sensor 1
The output values Q, P ₁ , P ₂ , Q ′, P ₁ ′ and P ₂ ′ obtained with time by 1 and the pressure sensors S ₁ and S ₂ are measured.
Then, in step 3, the change in pressure ratio (Pr = P ₂ / P ₁ ) between the inlet side and the outlet side of the impeller 2 dPr = Pr−P
The ratio dPr / dQ of r ′ and dQ = Q−Q ′ is calculated.

Then, in step 4, it is judged whether or not this ratio exceeds a predetermined limit value (= 0). If it exceeds the limit value, in step 5, the inlet guide vanes are rotated in the closing direction. Determine if is possible. When the inlet guide vane cannot be rotated in the closing direction, the operation is stopped or a warning to that effect is issued in step 6. If the inlet guide vane angle can be rotated in the closing direction in step 5, it is rotated by a constant pitch angle in step 7, and the process returns to step 2 and follows the same steps.

When dPr / dQ does not exceed the limit value in step 4, the head H is measured in step 8 and it is confirmed in step 9 whether or not this is the target value. Is continued (step 10). If the target value has not been reached, it is judged in step 11 whether or not the rotation speed exceeds a predetermined limit value, and if it exceeds the limit value, further operation is impossible, so operation is stopped or a warning is issued in step 12. Output. If the number of revolutions is less than or equal to the limit value, the number of revolutions is increased by a fixed pitch in step 13, the process returns to step 2 and the following steps are repeated.

It has been found that the above pressure ratio Pr is effective as an index showing the operating state of the impeller of the fluid machine.
FIG. 5 shows the relationship between the flow rate and the pressure ratio of the impeller inlet / outlet when the flow rate is changed by setting the angle of the inlet guide vane to 0 ° and 60 °. Then, when Q / Qref = 0.6, when the inlet guide vane angle is 60 degrees, minute vibrations start to occur at Q / Qref = 0.4 (Qref is the flow rate at the design point of the fluid machine. ). From this, Q / Q which is a steady operation state
When moving from the region of ref = 1, dPr /
It can be seen that when dQ = 0 is set as a limit value and this exceeds 0, a countermeasure may be taken.

FIG. 6 shows one change pattern when the operation is controlled by using this embodiment. For example, in the initial setting, the inlet guide vane angle is 0 degree and the impeller rotational speed is N.
_{When the} operation is performed with ₀ and the flow rate gradually decreases, Q /
At Qref = 0.75, dPr / dQ = 0 and operation becomes impossible (step 4), so the inlet guide vanes are rotated up to an angle of 60 degrees (step 7). Here, a predetermined head cannot be obtained at this number of rotations of N ₀ ,
By increasing the rotation speed by 10% (step 13), it was possible to obtain a predetermined head with a flow rate of Q / Qref = 0.75. As described above, according to the method and apparatus of the present invention, the operating state of the impeller is quickly grasped by using the pressure ratio Pr as an index and the operating conditions of the fluid machine are adjusted, so that the fluid machine is operated in a stable state. be able to.

FIG. 7 shows a second embodiment of the method of the present invention, in which the relative speed ratio Lc before and after the impeller 2 is used as an index for grasping the operating state of the impeller 2. In this method, after the initialization is performed in step 1, the flow rate Q and the rotation speed N of the impeller are measured in step 2. Then, in step 3, the ratio (L _c = W _1s / W ₂ ) of the relative speed to the impeller on the inlet side and the outlet side of the impeller is calculated based on these measured values. Then, in step 4, it is determined whether or not this Lc exceeds a predetermined limit value, and when it exceeds the limit value, it is determined in step 5 whether or not the inlet guide vane can be rotated in the closing direction. . When the inlet guide vane cannot be rotated in the closing direction, the operation is stopped or a warning to that effect is issued in step 6. Since the same steps as those in the embodiment shown in FIG. 4 are performed below, the description thereof will be omitted.

Lc in the arithmetic processing unit 21 is obtained by the following method. First, the peripheral velocities (U _1s , U _2s ) at the inlet and outlet of the impeller are obtained from the rotational speed of the impeller. Next, the radial velocity component Cm ₂ at the impeller exit is determined by the following equation using the flow rate Q measured by the flow rate sensor 11. Cm ₂ = Q / πD ₂ b ₂ B Here, D ₂ is the impeller outer diameter, b ₂ is the impeller outlet width, and B is the blockage coefficient. The circumferential velocity component Cu ₂ is similarly obtained by the following equation. Cu ₂ = σU ₂ −Cm ₂ cotβ ₂ Here, σ is a slip coefficient, and U ₂ is a circumferential velocity. Using these, the relative velocity W ₂ on the outlet side is calculated by the following equation. W ₂ = {Cm ₂ ² + (U ₂ −Cu ₂ ) ² } ^1/2 where β ₂ is the blade outlet angle from the circumferential direction.

Next, the impeller inlet radial velocity component Cm ₁
Is calculated by the following equation using the flow rate Q measured by the flow rate sensor. Cm ₁ = Q / πD ₁ b ₁ B Next, Cu ₁ is obtained from the inlet guide vane angle. Then, the relative speed W _1s on the inlet side of the impeller is calculated from the following equation. W _1s = {Cm ₁ ² + (U _1s −Cu ₁ ) ² } ^1/2 Lc = W _1s / W ₂

The relative speed ratio Lc thus obtained is
It was found that it is effective as an index showing the operating state of the impeller of a fluid machine. FIG. 8 shows the relationship between the flow rate and the relative speed ratio when the angle of the inlet guide vanes is set to 0 degrees and 60 degrees and the flow rate is changed in a certain fluid machine. Here, the flow rate Q / Qref is shown. Is suddenly unstable when the value decreases from the steady state of 1 to 0.6 or less. That is, it has been found that the state of caution is required when Lc = W _1s / W ₂ is larger than 2. Therefore, in step 3 of FIG. 7, for example, 2.0 may be used as the limit value of Lc obtained as described above.

In the above embodiment, the diffuser blade 3a is not controlled to move, but the diffuser 3
The diffuser vanes may be controlled to optimize the flow at. FIG. 9 shows an example of such a control method, in which the diffuser blades are controlled according to a preset relationship between the flow rate and the blade angle. This relationship is based on the fact that the stable blade angle with the smallest fluctuation of the indicated value of the pressure sensor arranged at the predetermined position of the fluid machine is uniquely determined with respect to the flow rate.

In this flow chart, α is such a stable angle and β is an appropriate angle of attack. In this example, the diffuser blade angle ξ is emphasized in the range where the flow rate Q is smaller than a certain reference flow rate Qs close to the design flow rate of the fluid machine.
= Α (step 3), and when Q is larger than Qs, importance is attached to efficiency and ξ = α + β. This flow may be used by inserting it into an appropriate place (for example, *) in the flow chart of FIG. 4 or 7.

FIGS. 10 and 11 show a fluid machine according to another embodiment of the present invention. In the apparatus of the embodiment shown in FIG. 1, a discharge valve 27 for controlling the discharge amount in the discharge pipe 5,
A fourth control drive device 28 for driving this is provided.
The control portion of the fourth control drive unit 28 is the arithmetic processing unit 2
1 connected.

FIG. 12 shows the flow of control of the fluid machine of this embodiment. In the embodiment of FIG. 4, the pressure ratio (Pr = P ₁ / P ₂ ) changes dPr under particularly stable conditions. = P
While it may not be possible to calculate the ratio dPr / dQ between r-Pr 'and dQ = Q-Q', in this example, the ratio dPr / d is positively adjusted by adjusting the discharge valve opening.
Q is calculated and control is actively performed.

That is, in the initial setting of step 1, a desired flow rate Qt is input. In step 2, the flow sensor 11 and the pressure sensors S ₁ and S ₂ perform the first measurement, and in step 3, Q and Qt are compared. Q>
If Qt, the discharge valve is closed by a predetermined pitch angle in step 4, and if Q ≦ Qt, the discharge valve is opened by a predetermined pitch angle in step 5. Then, in step 7, the second measurement is performed, and in step 6, the ratio dPr / d is calculated based on the _two measurement values Q, P ₁ , P ₂ , Q ′, P ₁ ′ and P ₂ ′.
Calculate Q. Since step 8 and subsequent steps are basically the same as those in FIG. 4, description thereof will be omitted.

In this example, the degree of flow stability in the impeller can be calculated by artificially changing the load. It goes without saying that the control of the diffuser blade as shown in FIG. 9 may be performed in this embodiment as well. In the above embodiments, the plurality of control drive devices are provided separately for each function, but one control drive device may be provided.

[0031]

As described above, according to the present invention,
The instability phenomenon that occurs when the fluid machine is operated in a flow rate range other than the design point flow rate can be avoided, and the fluid machine can be stably operated in a wide flow rate range.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a single-stage centrifugal compressor which is an example of a fluid machine with variable guide vanes according to the present invention.

FIG. 2 is a partial side view showing a single-stage centrifugal compressor which is an example of a fluid machine with variable guide vanes according to the present invention.

FIG. 3 is a block diagram showing an embodiment of a fluid machine with variable guide vanes according to the present invention.

FIG. 4 is a flowchart showing a processing procedure of the fluid machine with variable guide vanes of the present invention.

FIG. 5 is a graph showing a relationship between a flow rate of a fluid machine and a pressure ratio.

FIG. 6 is a graph showing a relationship between a flow rate of a fluid machine and a relative speed ratio.

FIG. 7 is a flowchart showing a processing procedure of another embodiment of the fluid machine of the present invention.

FIG. 8 is a graph showing a relationship between a flow rate of a fluid machine and a relative speed ratio.

FIG. 9 is a flowchart showing a processing procedure of another embodiment of the fluid machine of the present invention.

FIG. 10 is a vertical cross-sectional view showing another example of a single-stage centrifugal compressor that is a fluid machine with variable guide vanes according to the present invention.

11 is a block diagram of a control mechanism of the fluid machine with variable guide vanes of FIG.

12 is a flowchart showing a processing procedure of the fluid machine with variable guide vanes of FIG.

[Explanation of symbols]

1 Suction pipe 2 Impeller 3 Diffuser 3a Diffuser blade 5 Discharge pipe 6 Entrance guide vane 5 First control drive device 7,9 Reduction gear 8,10 Actuator 21 Arithmetic processing device 21a Inlet blade angle calculation part 21b Variation amount judgment part 21c Memory Part 23 Input device 24 First control drive device 25 Second control drive device 26 Third control drive device 27 Discharge valve 28 Fourth control drive device S ₁ , S ₂ , S ₃ Pressure sensor

[Procedure amendment]

[Submission date] October 25, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

A plurality of fan-shaped inlet guide vanes 6 are arranged in the suction pipe 1 in the circumferential direction, and an actuator 8 is connected thereto via a transmission mechanism 7. The diffuser vane 3 a is arranged on the diffuser 3 on the downstream side, which is also connected to the actuator 10 via the transmission mechanism 9. The suction pipe 1 is provided with a flow rate sensor 11 for measuring the suction flow rate, and pressure sensors S _{1 to} S ₃ are provided before and after the impeller 2. That is, the sensor S ₁
Is attached to the latter stage of the suction pipe 1 , the sensor S ₂ is attached to two inlets of the diffuser 3 , and the sensor S ₃ is attached to the discharge pipe 5 . The shaft of the impeller 2 is provided with a rotation speed sensor 12, the diffuser 3 is provided with a diffuser angle sensor 15, and the inlet guide vane 6 is provided with an inlet guide vane angle sensor 16.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 11

Claims (6)

[Claims] 1. In a fluid machine having an inlet guide vane and an impeller, an index value representing the degree of flow stability in the impeller is calculated based on data obtained during the operation of the fluid machine, and the index value is calculated. A fluid characterized by controlling the opening degree of the inlet guide vanes and the rotational speed of the impeller of the fluid machine so that the value falls within a predetermined range and the flow rate and the head reach the values required for the fluid machine. Machine operation control method. 2. The operation control method for a fluid machine according to claim 1, wherein the index value is a ratio of flow velocities at an inlet and an outlet of the impeller. 3. The method for controlling the operation of a fluid machine according to claim 1, wherein the index value is a rate of change of a ratio of pressures at an inlet and an outlet of the impeller with respect to a flow rate. 4. A discharge adjusting valve for adjusting a discharge amount is provided on the downstream side of a fluid machine, and an opening of the discharge adjusting valve is changed to obtain a rate of change of the pressure ratio with respect to a flow rate. 4. The operation control method for a fluid machine according to item 3. 5. The operation control method for a fluid machine according to claim 1, further comprising a control for adjusting an angle of the diffuser blade to an angle that is most stable with respect to the measured flow rate. 6. A fluid machine having an inlet guide vane with a variable angle and an impeller with a variable rotational speed, a sensor for detecting operation data at a predetermined position of the fluid machine, and a detection value of the sensor based on the detected value. An index value indicating the degree of flow stability in the impeller is calculated, and the inlet guide vanes of the fluid machine are adjusted so that the index value falls within a predetermined range, and the flow rate and the head reach values required for the fluid machine. A fluid machine having a control means for controlling the opening degree of and the rotation speed of the impeller.