JP3093958B2 - Fluid machinery with variable guide vanes - Google Patents

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 or diagonal fluid pump, a blower for gas, a compressor, and the like, and more particularly to a fluid machine having inlet guide vanes and diffuser vanes.

[0002]

2. Description of the Related Art Conventionally, when a centrifugal or mixed flow pump is operated in a flow rate region other than the design point, flow separation occurs in each component such as an impeller and a diffuser. There is a disadvantage that the efficiency of the pump is reduced as compared with the design point flow rate.

[0003] In order to solve this problem, the inlet guide vanes and diffuser vanes are made variable so that each guide vane can be optimally adapted to the flow flowing into and out of the impeller. Attempts have been made to improve performance by adjusting the angle of the blades.

A typical example is Japanese Patent Publication No. 4-181.
No. 58, Japanese Patent Publication No. 4-18159, JP-A-63-239
398 and JP-A-63-230999. However, it is necessary to grasp the overall performance of the compressor at various angles of the inlet guide vane and the diffuser vane as a dimensionless characteristic. When calculating the angle, the optimum point cannot be determined unless the overall performance of the compressor is measured at several points where the angle is changed, and it takes a long time to determine the guide blade angle. Also, the control method becomes very complicated,
There is a disadvantage that the cost of the apparatus and the control software are very high.

On the other hand, as a method of calculating the flow angle at the exit of the impeller, there is JP-A-4-81598. In this method, there are some assumptions in the method of calculating the flow angle,
In general, at the impeller outlet, the flow is distorted, so that it is impossible to calculate the flow angle from the static pressure on the wall surface. In the region where the flow is unstable, there are many disadvantages such as a problem in accuracy.

If the angle of the inlet guide vane or the diffuser vane is changed, the characteristics of the pump will be greatly changed. A method has been adopted in which a performance test is performed in detail for each of the angles in advance, and the angles of the entrance guide blades and the diffuser blades are determined based on the test results.

Furthermore, when the operation of the pump is automatically controlled by using this method, the angles of the inlet guide vanes and the diffuser vanes are changed at least three times (Japanese Patent Publication No. 4-1815).
No. 9), it is necessary to determine the angle of the inlet guide vanes and diffuser vanes by grasping the operating state of the pump at that point in time, and it takes time to set the pump, especially in the vicinity of the surging point, etc. There are many problems at the operating point where the state must be determined instantaneously as described above. Also,
In the control in which the number of revolutions is changed, these controls are more difficult, and the control device is expensive, and the cost of the device and the cost of the control software are high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has a variable configuration capable of operating a fluid machine in a wide flow range while avoiding an unstable phenomenon that occurs when the fluid machine is operated in a flow range other than a design point flow rate. It is an object to provide a fluid machine with guide vanes.

[0009]

According to a first aspect of the present invention, there is provided an input device for inputting a required operating state of a fluid machine in a fluid machine having an inlet guide vane and a diffuser vane, and the input device. And an arithmetic processing unit for calculating the angle of the inlet guide blade from the detected suction flow rate and the head so as to achieve the operating state input by the controller, and a first control for driving and controlling the inlet guide blade to the calculated angle. And a driving device, and the arithmetic processing device is provided with a reference flow rate
Pressure coefficient characteristic curve and a specific curve through the required operating point
And the required operating point flow pressure coefficient.
A fluid machine with variable guide vanes characterized by determining an inlet guide vane angle . This ensures that the processing unit, the intersection with a particular curve passing through the operating point and the required reference flow rate and pressure coefficient curve, and the inlet guide vane angle based on the flow rate pressure coefficient of the required operating point It is determined, and based on this, the 1st control drive device drives and controls the entrance guide blade to the calculated angle, and the required operating state input from the input device is achieved. Further, a second control for determining the diffuser blade angle based on the relationship between the suction flow rate and the diffuser blade angle previously determined in the arithmetic processing device, and further controlling the drive of the diffuser blade to the angle determined in the arithmetic processing device. You may make it have a drive device. Thereby, in the arithmetic processing unit, the diffuser blade angle is determined based on the relationship between the suction flow rate and the diffuser blade angle determined in advance, and the second drive control device drives and controls the diffuser blade to the determined angle. . The relationship between the suction flow rate and the diffuser blade angle may be a substantially linear relationship. Thus, the relationship between the suction flow rate and the diffuser blade angle is given as a substantially linear relationship. Further, the gradient of the linear relationship may be determined by the rotation speed of the impeller. Thus, the gradient of the linear relationship is determined by the rotation speed of the impeller. Further, a third control drive device for controlling the rotation speed of the fluid machine may be provided. As a result, in addition to the control by the first or second drive control device, the rotation speed control of the fluid machine is performed by the third drive control device, whereby the necessary operating state input from the input device is achieved. .

[0010]

According to the first aspect of the present invention, the arithmetic processing unit calculates the angle of the inlet guide blade from the detected suction flow rate and the head, and the first control drive unit calculates the angle of the inlet guide blade. In this way, the required operating state input from the input device is achieved.

[0011]

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

FIGS. 1 and 2 are views showing a single-stage centrifugal compressor to which the present invention is applied. FIG.
Is a partial side view thereof. The impeller 2 gives kinetic energy to the fluid from the suction pipe 1 and sends it to the diffuser 3 to increase the pressure, and sends it out of 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 to the inlet guide vanes 6 via a transmission mechanism 7. A diffuser blade 3 a is arranged on the diffuser 3 on the downstream side, and is also connected to an actuator 10 via a transmission mechanism 9. The suction pipe 1 is provided with a flow rate sensor 11 for measuring a suction flow rate, and the discharge pipe 5 is provided with a pressure sensor 12 for measuring a discharge pressure (head). A control device 13 for controlling the two actuators 8 and 10 is provided, and output terminals of the flow sensor 11 and the pressure sensor 12 are connected thereto.

FIG. 3 is a block diagram showing the configuration of the control device. As shown in this figure, the fluid machine with variable guide vanes measures and calculates the rotation speed, suction flow rate, and head elevation of the fluid machine, and determines an optimal angle of the diffuser blade 3a based on the suction flow rate, A storage unit 22 for storing in advance the fluid machine performance when the inlet guide vanes 6 are fully opened; and a storage unit 22 for further storing an input unit 23 for inputting a required operating state of the fluid machine.
A first control drive device 24 that variably controls the inlet guide blade 6;
A second control drive device 25 for variably controlling the diffuser blades 3a and a third control drive device 26 for controlling the rotation speed of the impeller 2, that is, the rotation speed of the fluid machine, are provided.

In this fluid machine, the angle of the entrance guide blade 6 is calculated by using an arithmetic processing unit U including an arithmetic unit 21 and a storage unit 22 so that the required performance input by the input device 23 can be exhibited. Drive control of the inlet guide blade 6, drive control of the diffuser blade 3a so as to have an optimum diffuser blade angle (described later) determined by the suction flow rate, and further drive control of the number of rotations to drive the operation. I have.

FIG. 4 shows a control device for setting the inlet guide vanes 6 so as to exhibit the required performance of the fluid machine, and for controlling the operation of the diffuser vanes 3a to perform a stable operation while preventing surging. It shows a flowchart. In the setting of the entrance guide blade 6, the impeller 2
Of the inlet guide vanes corresponding to the rotation speed N, the required flow rate Q, and the head H are determined.

First, in the case of a fluid machine whose rotation speed can be changed, an appropriate rotation speed is set in advance. In step 1, the required flow rate Q and head H are input, and in step 2, the flow coefficient φ and the pressure coefficient ψ are calculated. Next, in step 3, a quadratic curve coefficient passing through the flow coefficient φ and the pressure coefficient 、 is calculated. In step 4, the intersections φ ′ and ψ ′ with the characteristic when the inlet guide vane is at 0 ° are calculated, and in step 5 Then, the angle of the entrance guide blade is calculated from the following equation (k is a constant). α = arctan (k (ψ′−ψ) / φ ′) Next, at step 6, the entrance guide vane angle control is performed, and at step 7, it is determined whether or not α is 0 (fully open). If it is not 0, the head and the flow rate are measured in step 9 and φ ″,
Then, it is determined in step 10 whether or not the head H has an appropriate value.
In step 12, α ′ is calculated, and in step 12, (α−α ′)
And then return to step 6.

If α is 0 in step 6, if the number of revolutions cannot be changed, such a request is not satisfied, so the process returns to step 1 to change the setting. If the number of revolutions can be changed, the number of revolutions is changed in step 8 and the procedure goes to step 9. If the head H is at the proper value in step 10, the drive of the diffuser blade 3a is controlled in steps 13 and subsequent steps. That is, based on the suction flow rate measured in step 9, the diffuser blade angle is determined in step 13 from the relationship between the dimensionless suction flow rate and the diffuser blade angle shown in FIG. Then, at step 14, the diffuser blade angle is changed. The head and the flow rate at that time are measured, and step 15
To calculate φ ″, ψ ″. Next, at step 16, it is determined whether or not the head H has a predetermined value. If not, the process returns to step 11.

The graph of FIG. 7 used in step 13 summarizes data obtained by using the compressor. The horizontal axis shows the dimensionless flow obtained by dimensioning the flow at each operating point by the flow at the design point, and the vertical axis shows the angle of the diffuser blade. Here, the blade angle was changed at the flow rate and the rotation speed, and the blade angle when the flow was most stable was plotted. The stability of the flow was based on the fluctuation of the pressure sensor installed in the piping or pump casing.

The method of obtaining the above equation will be described below. FIG.
FIG. 4 is an explanatory diagram of a characteristic curve and a resistance curve of the fluid machine. As an initial condition, the performance when the entrance guide vane is at 0 degrees is known. Next, the flow rate coefficient φ (4 · Q / (π · D ₂ ² · U) is calculated from the flow rate Q and the head H of the optional requirements (given requirements).
₂₎₎ and pressure coefficient ψ (g · H / (U 2 2)) is calculated. Assuming that a resistance curve passing through the arbitrary essential points (φ, ψ) and the origin (if there is a fixed resistance, its value is known, and the value of the intercept of the ψ axis is obtained) as a quadratic curve, this resistance curve Find the coefficient of. Coordinates (φ ′, ψ ′) of the intersection of this resistance curve and the characteristic curve at the known entrance guide vane of 0 °
Is obtained by numerical calculation or the like.

From the coordinate value φ ′, the flow rate Q ′ is obtained by the following equation. When Q '= φ' · π · D a _{² 2} · U _2/4 impeller inlet area and A _1, it is obtained the impeller inlet axial velocity Cm ₁ from the following equation. _{Cm 1 = Q '/ A 1} = φ' · π · D 2 2 · U 2 / (4 ·
A ₁ ) The head H ′ of the fluid machine is composed of a product U ₂ · Cu _{2 of the} circumferential speed U _{2 of the} impeller outlet and the circumferential component Cu ₂ of the absolute speed, and a circumferential direction of the circumferential speed U _{1 of the} impeller inlet and the absolute speed. from the difference of the product U ₁ · Cu ₁ with component Cu ₁ obtained by the following equation. H ′ = (U ₂ .Cu ₂ −U ₁ .Cu ₁ ) / g Here, since ψ ′ = (g · H ′ / U ₂ ² ), ψ ′ = (U ₂ .Cu ₂ −U ₁₎ · Cu ₁₎ / U _{² 2} become. Now, since the entrance guide vane angle is set to 0 degree, the circumferential component Cu ₁ of the absolute velocity becomes 0. Thus, the circumferential velocity component Cu ₂ of the absolute velocity of the impeller outlet is obtained by the following expression. Cu ₂ = U ₂ · ψ '

According to the study of the present inventor, the circumferential velocity component Cu ₂ of the absolute velocity at the impeller outlet depends only on the flow rate,
It turns out that it does not change with the entrance guide blade angle.
By using this result, it is possible to ψ
^{_{Is, ψ = (U 2 2 ·}} ψ'-U 1 · Cu 1) / U 2 2 = Since denoted _{ψ'-U 1 · Cu 1 /} U 2 2, the peripheral of the absolute velocity at the impeller inlet The directional velocity component Cu ₁ is expressed as Cu ₁ = (ψ′−ψ) ・ U ₂ ² / U ₁ .

The angle of the inlet guide vane to satisfy any essential point is, when the root mean square diameter at the impeller inlet and _{D 1 rms, α 1 = arctan} (Cu 1 / Cm 1) = arctan (A 1 · ( _{ψ'-ψ) · U 2 /} (D 2 2 · φ '·
U ₁ )) = arctan (A ₁ · (ψ′-ψ) / (D ₂ · D ₁ rms ·
φ ′)) Here, assuming that the constant k is k = A ₁ / (D ₂ · D ₁ rms), α ₁ = arctan (k (ψ′−φ) / φ ′), and the above equation is obtained.

FIG. 6 is a diagram for explaining a method of determining the diffuser blade angle in the arithmetic processing unit U. In the case of a pump, the optimum angle of the diffuser blade at the impeller outlet with respect to the dimensionless suction flow rate when the rotation speed is changed is represented by a substantially single straight line (straight line N _{1 in} FIG. 6), that is,
The flow rate and the optimal blade angle are proportional. If the compressor is the slope of the line for each rotational speed for compression of the gas it is different (linear N ₁ to N ₄ in FIG. 6).

FIG. 7 is data supporting the graph of FIG. 6, and summarizes data obtained by the inventor using a compressor. The horizontal axis represents the dimensionless flow rate obtained by dimensioning the flow rate at each operating point by the flow rate at the design point, and the vertical axis represents the angle of the diffuser blade according to the present invention. Here, the blade angle was changed at the flow rate and the rotation speed, and the blade angle when the flow was most stable was plotted. The flow stability is
The fluctuation of the pressure sensor installed in the piping or pump casing was used as a guide. In this figure, the mark ○ indicates that the peripheral speed Mach number of the impeller is 1.21 and the angle of the inlet guide blade is 0 degree, and the mark □ indicates that the peripheral speed Mach number of the impeller is 0.87 and the inlet guide blade is When the angle is 0 degrees, the mark △ indicates that the peripheral speed Mach number of the impeller is 0.87.
9 is a plot of an experimental result when the angle of the entrance guide blade is 60 degrees.

The arithmetic processing unit U determines the optimum diffuser blade angle from the rotation speed and the suction flow rate of the impeller 2 along this graph. In the case of a compressor, first, the gradient of a straight line to be used as a reference is determined based on the peripheral speed Mach number of the impeller, that is, the rotation speed. This inclination can be obtained by calculation by predicting the state of the impeller exit. In the case of a pump, one straight line may be used because the target fluid is incompressible. Next, the blade angle of the diffuser is determined according to the measured flow rate. When the rotation speed is the same, the angle of the diffuser blade does not change even if the angle of the inlet guide blade changes.

If the head does not satisfy the predetermined value even when the diffuser blades are controlled in this way, the operation is further performed while controlling the rotation speed to avoid an unstable state. Therefore, in any state, if the dimensionless flow rate of the compressor is known, the operation can be performed with the angle of the diffuser blade optimally matched to the flow at the exit of the impeller.

As described above, in this embodiment, the input device 23
Is calculated by calculating the angle of the inlet guide blade 6 so that the required performance input can be exhibited, and the drive is performed by controlling the drive of the inlet guide blade 6. When the angle of the inlet guide vanes 6 is changed, the flow state inside the impeller changes, and therefore the flow state at the impeller outlet also changes. However, the dimensionless suction flow rate of the compressor was measured, and FIG.
The optimal angle of the diffuser blade 3a is uniquely determined according to the relationship.

As an example in FIG. 8, the horizontal axis represents the dimensionless flow rate of the centrifugal compressor equipped with this device, and the vertical axis represents the performance of the centrifugal compressor equipped with this device, taking the pressure coefficient and efficiency from above. However, it was confirmed that highly efficient operation was possible in a wide operation range.

FIG. 9 shows the overall performance of the centrifugal compressor when the diffuser blades are fixed and only the inlet guide blades are variable. The performance of the apparatus according to the present invention shown in FIG. It can be seen that the performance is greatly improved for both large flow rates and small flow rates, and the effect of the present invention is clear.

In the embodiment shown in FIGS. 1 to 8, the control drive device is divided into the first, second and third control drive devices according to their functions, but may be one control drive device.

[0031]

As described above, according to the present invention, the fluid machine can be operated stably in a wide flow rate range by avoiding an unstable phenomenon that occurs when the fluid machine is operated in a flow rate range other than the design point flow rate. Can drive.

[Brief description of the drawings]

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

FIG. 3 is a block diagram showing one embodiment of a fluid machine with variable guide blades 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 an explanatory diagram of a characteristic curve and a resistance curve of the fluid machine.

FIG. 6 is a diagram showing a relationship between a dimensionless flow rate and a diffuser blade angle.

FIG. 7 is a view showing data supporting the data shown in FIG. 7;

FIG. 8 is a diagram showing the relationship between the dimensionless flow rate, the efficiency, and the head coefficient of the apparatus of the present invention.

FIG. 9 is a diagram showing a relationship between a dimensionless flow rate, efficiency, and a head coefficient of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation part 2 Storage part 3 Input device 4 Entrance guide blade 5 First control drive device 6 Diffuser blade 7 Second control drive device 8 Impeller 9 Third control drive device U Processing device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F04D 27/02 F04D 27/00 101

Claims (1)

(57) [Claims] An input device for inputting a required operating state of a fluid machine in a fluid machine having inlet guide vanes, and a suction detected so as to achieve the operating state input by the input device. An arithmetic processing unit for calculating the angle of the inlet guide blade from the flow rate and the head; and a first drive control for driving the inlet guide blade to the calculated angle.
And a control drive device , wherein the arithmetic processing device is
Specification through flow rate / pressure coefficient characteristic curve and required operating point
Intersection with the curve and the required operating point flow pressure coefficient
A fluid machine with variable guide vanes, characterized in that an inlet guide vane angle is determined based on the following .