JPH01394A - Compressor surging prevention device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to compressors for gas turbines or industrial use, and is particularly suitable when it is necessary to avoid operating the compressor in unstable operating ranges such as surging. This invention relates to a surging prevention device for a compressor.

[Conventional technology]

Depending on the operating conditions, compressors such as axial flow type and centrifugal type compressors may enter unstable operation called surging. The surging phenomenon is accompanied by large pressure fluctuations and flow velocity fluctuations, so it increases blade vibration and shaft vibration, and in extreme cases, it can prevent blade damage accidents.The method described in "Blowers and Compressors", pages 356 to 2358, will be used to explain this phenomenon. .

FIG. 2 shows the general characteristics of a conventional compressor. In FIG. 2, curves 1, 2, . . . 4 show the characteristics of the flow rate and discharge pressure when the compressor rotation speed is constant, and the broken line 5 shows the surge line. In a turbo compressor, the stable operation area is on the right side of the broken line 5, but in the left side area, surging, rotational stalling, etc. occur, so the compressor cannot operate stably. Therefore, there is a need for a surging prevention control device for the compressor that monitors and controls the compressor to prevent it from entering such an unstable operating range.

1. of a turbo compressor equipped with a conventional surging prevention device. The growth is shown in Figure 3. A suction pipe 7 is connected to the upstream side of the compressor 6, and a discharge pipe 8 is connected to the downstream side of the compressor 6. The discharge pipe 8 is a branch pipe 9 having an air discharge valve 10.
It is connected to the. In the configuration shown in FIG. 3, a characteristic map of the compressor 6 determined in advance through a preliminary test is stored in the storage device 14.

Outputs from a discharge pressure detector 11 and a flow rate detector 12 of the compressor 6 are led to an arithmetic unit 13. The output from the arithmetic device 13 is led to the blow-off valve control device 15, which determines whether the operating point of the compressor 6 is in the stable region or the unstable region on the compressor characteristic map stored in the storage device 14. Compare and judge.

When the compressor is used while changing its operating point, when the compressor operating point reaches the unstable region from the stable region of the compressor, the blow-off valve 10 is opened and the compressor is controlled to remain within the stable operating region.

In this way, entry into the surging region can be prevented.

[Problem that the invention seeks to solve]

The method according to the above-mentioned known technology is effective when the characteristic map of the compressor remains constant, but the characteristic map often changes over time. In other words, when deposits such as dust accumulate on the blade surface, the performance of the compressor decreases, and the "surge line (before performance deterioration)" shown by the solid line in Figure 4 changes to the "surge line (before performance deterioration)" shown by the broken line in Figure 4. After)
The stable operating range becomes narrower. Therefore, when the characteristic map at the time of compressor installation is used as a criterion for determination, it is necessary to set a wide margin area A as shown in FIG. For this reason, the conventional method has the problem of narrowing the stable operating range and reducing the accuracy of surge point prediction. Also, -
The efficiency of the in-shell compressor reaches its highest value in the region close to the surge line, but as mentioned above, the conventional method, which requires a wide surge margin A, has the problem of operating at an operating point where the compressor efficiency is low. There were also points.

The present invention has been made based on the above-mentioned matters, and aims to perform highly accurate surge predictive control regardless of performance deterioration of the compressor due to aging, and to achieve higher performance of the compressor.

[Means for solving problems]

The above problem occurs when the inlet pressure of the compressor is detected in a compressor equipped with multiple rows of stator blades arranged inside the casing and rows of rotating rotor blades arranged between the rows of stator blades. (b) an inlet temperature detector to detect the inlet temperature; (c) a discharge pressure detector to detect the compressor discharge pressure; and (d) a discharge temperature detector to detect the discharge temperature. ,
(e) suction flow rate detection means for detecting the compressor suction flow rate;

(f) a rotation speed detector that detects the rotation speed of the compressor rotor, and (g) an inlet pressure detector and an inlet temperature detector.

Discharge pressure detector, discharge temperature detector, suction flow rate detection means 2
(h) an arithmetic device that calculates a power change rate or a power equivalent amount change rate with respect to the pressure ratio or suction flow rate at a constant corrected rotation speed using the output signal from the rotation speed detector;
a storage device that stores a limit value of the power change rate or the power equivalent amount change rate of the compressor; The problem is solved by providing a compressor control device to control the problem.

Further, the above problem is that in the compressor, (a) an inlet pressure detector that detects the inlet pressure of the compressor, (b) an inlet temperature detector that detects the inlet temperature, and (c) an inlet temperature detector that detects the compressor discharge pressure. (d) a discharge temperature detector to detect discharge temperature; and (d) a discharge temperature detector to detect discharge temperature.

(e) suction flow rate detection means for detecting the compressor suction flow rate;
(f) A rotation speed detector is provided to detect the rotation speed of the compressor rotor, and (j) the compressor division position is set at one or more compressor division positions located between the compressor inlet section and the discharge section. (k) a division position temperature detector for detecting the division position temperature; and (Q) a division position flow rate detection means for detecting the division position flow rate; (m) the inlet; Pressure detector, inlet temperature detector.

Discharge pressure detector, discharge temperature detector, suction flow rate detection means 2
Rotation speed detector 9 division positions Pressure detector 2 division positions Temperature detector 2 division positions Using the output signal from the flow rate detection means, each pressure ratio or (n) a calculator that calculates the power change rate or power equivalent change rate of each divided stage compressor with respect to the suction flow rate; and (n) stores the limit value of the power change rate or power equivalent change rate of each divided stage compressor. (o) the rate of change in power or the rate of change in power equivalent of each divided stage compressor calculated by the arithmetic unit is for all divided stage compressors or for at least one divided stage compressor; A solution is also provided by providing a compressor control that controls to stay within each limit value.

[Effect]

A characteristic diagram of a typical compressor is shown in FIG. In FIG. 5, unlike the above-mentioned FIG. 2, the vertical axis is the pressure ratio π of the compressor, the horizontal axis is the corrected flow rate, and the parameter rotation speed is the corrected rotation speed d. Pressure ratio π.

Definition formulas for corrected flow rate -G and corrected rotational speed are as follows.

Ps/P.

Here, Pd: Compressor discharge pressure P! , : Compressor inlet pressure Ts : Compressor inlet temperature G : Compressor flow rate n : Compressor rotation speed TO : Compressor inlet base 4I temperature Po : Compressor inlet standard pressure In general, the characteristics of a compressor are compressor discharge pressure P5 Although it is influenced by the inlet temperature Ts, the influence of the compressor inlet state can be corrected by organizing the characteristics using the pressure ratio π, corrected flow rate τ, and corrected rotation speed 1 as parameters as described above. In other words, if the compressor characteristics are organized using a map such as that shown in FIG. 5, the compressor characteristics will not be affected by the inlet condition.

According to Inuyama's document ``Study on compressor surge'' (Transactions of the Japan Society of Mechanical Engineers, Vol. 44, No. 387, p. 3810-3817), this surge point in compressor characteristics is In the case of , it is stated that this is the point at which the maximum power is exhibited on the compressor characteristics at a constant corrected rotation speed.

In the above literature, instead of power, it is the power equivalent amount (π-1)
Using the maximum value of XG- (see FIG. 6), comparisons are made with surge points experimentally determined from various compressors.

As a result, the surge points of both coincide with each other with high accuracy. In this way, the surge determination criterion that defines the surge point as the point where the power or power equivalent amount is maximum on the compressor characteristics at a fixed corrected rotation speed can be said to be highly accurate. However, the maximum power or maximum power equivalent cannot be determined until the compressor actually enters surging. Furthermore, since these values change due to the deterioration of blade row performance over time, it is practically difficult to judge surging based on the maximum value of power or power equivalent. Therefore.

If the rate of change in power or the rate of change in power equivalent amount on the compressor characteristics is used as the surge judgment j, 1 standard instead of the power or the equivalent amount of power, then the point where these rates of change become zero becomes the s-j point.

If the rate of change in power or the rate of change in power equivalent amount is used as a criterion for surging in this way, it becomes possible to predict surges with high accuracy regardless of S (row performance deterioration).In addition, it is not necessary to provide an unnecessarily large surge margin. Since there are no

Next, a method for calculating the rate of change in power based on the compressor characteristics at a fixed corrected rotation speed will be specifically explained. As an example, let us take the rate of change in power (dL/dπ) with respect to the pressure ratio π. Every time the pressure ratio changes by a pre-stored change ff1 (Δπ), the compressor inlet temperature T s changes.

Discharge temperature Ta and flow rate G are measured, and compressor power is calculated using the following equation.

L=G−Cp ・(Tt Ts) −
(4) Here, CP=f (Ts, Ta) is constant pressure specific heat.

The pressure ratio and power before and after the pressure ratio changes by Δπ are π0. When π and Lo are L, the change is d π In the above example, the method of calculating the power change rate with respect to the pressure ratio was described, but the power change rate with respect to the flow rate (dL/dG) can also be calculated using the same procedure if the flow rate is measured. Furthermore, it is possible to similarly determine the rate of change with respect to the pressure ratio or flow rate for the power equivalent amount.

Next, as shown in FIG. 7, a method for calculating the rate of change in power (dL/dπ) will be described when the corrected rotational speed changes from ττ to 1 while the pressure ratio changes by Δπ. If the point P on the corrected rotational speed i is proportionally converted to the rotational speed d under the condition of speed triangle similarity of the blade rows is R, then between the stones τ and 10', and.

The following relationships hold between π0 and π0'.

Here, K represents the ratio of specific heat at constant pressure to specific heat at constant volume.

By finding τ' and π0' at point R from equations (6) and (7), and finding Go' from Go' and equation (2), (d L/dπ) can be calculated using the following equation.

By the way, the above-mentioned compressor surging does not occur simultaneously in all stages, but is thought to occur directly due to the stall of the blade row in any stage. For example, in the high-speed rotation range of a compressor, surging tends to occur from the blade rows on the rear stage side. Furthermore, the decline in blade row performance due to aging is thought to occur in the front row of blades, where dust and other substances tend to accumulate on the blade surface. Therefore, by considering one compressor as two or more split-stage compressors connected in series and using the above-mentioned surging criteria for each split-stage compressor, more accurate surge prediction can be achieved. It becomes possible.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 shows an embodiment in which the compressor is used as a compressor for a single-shaft gas turbine. In this embodiment, the compressor 16 is made up of a plurality of rows of stator blades arranged inside a casing and a row of rotating rotor blades (both not shown) arranged between the rows of stator blades and rotating. The high pressure airflow is in the combustor 27
It becomes high temperature and high pressure, expands in the turbine 28, and then is discharged to the atmosphere. In this embodiment, the air compressor 16. turbine 28
．． The load 29 (for example, a generator) is placed on the -axis and rotates at the same rotation speed. When the load 29 is a generator, it is operated at a constant rotation speed unique to the power generation cycle. In such gas turbines, the operating point of compressor 16 is controlled by varying the fuel flow rate into combustor 27. In other words, if you increase the fuel and raise the gas temperature at the turbine inlet,
The volumetric flow rate of the hot gas turbine into the turbine increases and the pressure ratio of the compressor increases. On the other hand, if the fuel flow rate is reduced, the pressure ratio decreases and moves away from the surge point.6 In this embodiment, the compressor control device 2 changes the operating point of the compressor.
5, an opening control device for the fuel flow rate regulating valve 30 is provided. A compressor inlet pressure detector 1 is installed at the inlet of the compressor 16.
7. Inlet temperature detector 18. A discharge pressure detector 19 is installed at the compressor outlet. A discharge temperature detector 2o is installed.

Also, a rotation speed detector 2 that detects the rotation speed of the compressor rotor.
2 is installed at an appropriate position for detection.

At the inlet of the compressor, as the suction flow rate detection means 21, for example, the inlet pressure detector 17. A flow rate calculator is provided that uses output signals from the inlet temperature detector 18, discharge pressure detector 191, and rotation speed detector 22 to calculate the suction flow rate according to a predetermined calculation formula.

Further, the inlet pressure detector 17. inlet temperature detector 18;
Discharge pressure detector 19. The output signals from the discharge temperature detector 20, the suction flow rate detection means 21, and the rotational speed detector 22 are each led to a calculation device 23, which calculates the rate of change in power relative to the pressure ratio (dL/dπ). I do. Further, the limit value of (dL/dπ) is stored in advance in the storage device 24. This limit value may be a function of the corrected rotational speed or may be a constant that does not depend on the corrected rotational speed. Compressor power change rate (dL/d
π) is compared with the limit value stored in the storage device 24, and when (dL/dπ) reaches the limit value, the fuel regulating valve 3
The compressor control device 25 that controls the zero opening can restrict the flow of fuel into the combustor 27 and prevent it from entering the surging region. Further, in this embodiment, an alarm generating device 26 is provided to notify that the vehicle is approaching such a surge region. An alarm device 26, such as a bell or lamp, allows the gas turbine operator to recognize when the compressor is nearing its surge limit.

In the above embodiment, a case has been described in which the surging determination is performed using the rate of change in power relative to the pressure ratio (dL/dπ), but instead of this, the rate of change in power relative to the flow rate (dL/dτ) may be used. Further, instead of the power change rate, the same effect can be obtained by using the change rate of the power equivalent amount shown below as a surging determination criterion.

(1) (π-1) XG
=・(10)(2) HadX G
-(11) Here, Had: adiabatic head In the above embodiment (FIG. 1), as the compressor control device 25,
The opening control device of the fuel adjustment valve 30 was turned off by 5', but instead, as shown in Fig. 8, in a compressor equipped with an oil stage, an oil valve installed in the bleed air pipe 31 that discharges the bleed air flow to the outside is used. It may also be an opening control device for the air valve 32. If the compressor control device is an opening control device for the bleed valve 32, for example, when the power change rate reaches a limit value, the bleed valve 32 is opened to discharge the oil/air flow out of the compressor, and the surging region is eliminated. It is possible to prevent this from happening.

In addition, the suction flow rate detection means 2 in the above embodiment (Fig. 1)
1 is a differential pressure detector (not shown) that detects the differential pressure between the total pressure and the static pressure at the intake section of the compressor 16;

It may be a differential pressure type flow rate calculator that calculates the suction flow rate based on the output signal from the differential pressure detector and a predetermined correction coefficient.

Another embodiment of the present invention will be described with reference to FIG. FIG. 9 shows an embodiment in which the compressor 16 is used as a compressor for a single-shaft gas turbine, similar to the previous embodiment, and explanations are given for the components with the same drawing reference numbers as in FIG. 1. omitted.

In FIG. 2, the compressor division position C, such as the oil stage located between the compressor inlet part B and the discharge part, has a division stage position pressure detector 332 division stage position temperature detector 349 division stage position flow rate. A detection means (for example, an orifice flow meter, etc.) 35 is installed. The respective output signals from the dividing stage position pressure detector 332, the dividing stage position temperature detector 34, the dividing stage position flow rate detection means 35, and the inlet pressure detector 17.
Inlet temperature detector 18. Discharge pressure detector 19. Discharge temperature detector 20. Each output signal from the suction flow rate detection means 212 and the rotation speed detector 22 is guided to the arithmetic unit 23, and the arithmetic unit 23 calculates the power change rate (d L/d π) B-C, (d
L/d 7C) Calculate CD. The storage device 24 also stores in advance (dL/dπ) of each divided stage compressor.
The limit value of is memorized. This limit value may be a function of the corrected rotational speed or a constant. The dividing stage compressor power change rate (d
L/ d π) a-c, (d L/ d z) c-
o and the limit value stored in the storage device 24, and when (dL/dπ) reaches the limit value, the compressor control device 25, which controls the opening degree of the fuel adjustment valve 30, It is possible to restrict the inflow of fuel flow into the surging region 27 and prevent it from entering the surging region. In this case, for all split stage compressors, the power change rate of the split stage compressor is
Alternatively, at least one split stage compressor may be controlled to remain within each limit value. If surging inrush control is performed for each split-stage compressor or for at least one split-stage compressor in this way, highly accurate surge prevention control becomes possible.

In FIG. 9, the case where the compressor division position is one is explained, but effective surge control can be achieved by providing two or more division stage positions. These compressor division positions may be bleed stage positions or may not be bleed stage positions. If it is not the bleed stage position, the divided position flow rate detection means 35 can be omitted.

The compressor control device also includes an oil valve 32 shown in FIG.
A similar effect can be obtained even with the opening degree control device.

In addition, in the above embodiment, the surging determination was explained using the rate of change in power of the divided stage compressor with respect to the pressure ratio (dL/dπ), but instead, the rate of change of power of the divided stage compressor with respect to the flow rate (dr, /dG), Further, the same effect can be obtained by adopting a rate of change with respect to the pressure ratio or flow rate equivalent to the power of the divided stage compressor, such as (π-1)XG, H port x τ.

[Effects of the Invention] As described above, unlike conventional surging prevention devices, the present invention has a pressure ratio of
Judging the surging of a full-stage compressor or a split-stage compressor based on the power change rate or the power equivalent change rate with respect to the suction flow rate.Therefore, even if compressor performance deteriorates over time, surge prediction can be performed with high accuracy. It has excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention, FIG.
Figure 3 is an explanatory diagram of the prior art, Figures 4 to 7 are charts showing compressor characteristics, Figure 8 is an explanatory diagram of the compressor control device, and Figure 9 is an explanatory diagram of the compressor control device.
The figure is a system diagram showing a second embodiment of the present invention. 16... Compressor, 17... Inlet pressure detector, 18.
・Inlet temperature detector, 19...Discharge pressure detector, 20・
...Discharge temperature detector, 23... Arithmetic device, 24...
Storage device, 25... Compressor control device, 33... Divided stage position pressure detector, 34... Divided stage position temperature detector,
35...Division stage position flow rate detection means.

Claims (1)

[Claims] 1. In a compressor having a plurality of rows of stator blades arranged inside a casing and a row of rotating rotor blades arranged between the rows of stator blades, (a) of the compressor. (b) an inlet temperature detector that detects the inlet temperature of the compressor; (c) a discharge pressure detector that detects the discharge pressure of the compressor; (d) the compressor. a discharge temperature detector for detecting the discharge temperature of the compressor; (e) a flow rate detection means for detecting the suction flow rate of the compressor; and (f) a rotation speed detector for detecting the rotation speed of the compressor rotor; g) Using the output signals of each of the above-mentioned detectors and detection means, (a) the rate of change in power with respect to the pressure ratio or suction flow rate at a fixed corrected rotation speed, and (b) the change rate of power with respect to the pressure ratio or suction flow rate at a fixed corrected rotation speed. providing an arithmetic device for calculating at least one of the power equivalent rate of change; and (h) storing at least one of the limit value of the power rate of change and the limit value of the power equivalent rate of change; A storage device is provided, and (i) a compressor control device is provided to control the operating state of the compressor so that at least either the power change rate or the power equivalent change rate does not exceed a limit value. Compressor surging prevention device featuring: 2. The suction flow rate detection means includes the inlet pressure detector/
Claim 1, characterized in that it is a flow rate calculator that calculates a suction flow rate according to a predetermined calculation formula using output signals of an inlet temperature detector, a discharge pressure detector, and a rotation speed detector. Compressor surging prevention device described in . 3. The above-mentioned suction flow rate detecting means is provided with a "differential pressure converter that detects the differential pressure between the total pressure and the static pressure" at the compressor inlet, and also has "an output signal of the above-mentioned differential pressure converter and a predetermined Claim 1 is characterized in that the device is provided with a "differential pressure type flow rate calculator that calculates a suction flow rate based on a correction coefficient and a correction coefficient."
Compressor surging prevention device described in Section 1. 4. A patent characterized in that the compressor control device is equipped with an alarm means that is activated when at least one of the power change rate and the power equivalent change rate approaches a limit value. A surging prevention device for a compressor according to claim 1. 5. In a compressor having a plurality of rows of stator blades arranged inside a casing and a row of rotating rotor blades arranged between the rows of stator blades, (a) an inlet for detecting the inlet pressure of the compressor; a pressure detector; (b) an inlet temperature detector that detects the inlet temperature of the compressor; (c) a discharge pressure detector that detects the discharge pressure of the compressor; and (d) a discharge temperature of the compressor. A discharge temperature detector; (e) a flow rate detection means for detecting the suction flow rate of the compressor; (f) a rotation speed detector for detecting the rotation speed of the compressor rotor; and (j) a compressor inlet section. (k) a division position temperature detector that detects the temperature of the compressor division position; (l) a division position temperature detector that detects the temperature of the compressor division position; (m) Using the output signals of each of the above-mentioned detectors and detection means, a plurality of division stages configured with the compressor division position as a boundary is provided. For each of the compressors, an arithmetic device is provided that calculates "at least one of the power change rate and power equivalent amount change rate of each divided stage compressor" for "at least one of each pressure ratio and suction flow rate". , and (n) providing a storage device for storing at least one of the limit value of the power change rate and the limit value of the power equivalent amount change rate of each of the divided stage compressors, and (o) each of the divided stage compressors. A compressor comprising a compressor control device that controls at least one of the rate of change in power and the rate of change in power equivalent amount of at least one divided stage compressor so that it does not exceed respective limit values. anti-surging device. 6. The suction flow rate detection means includes the inlet pressure detector/
Claim 5, characterized in that it is a flow rate calculator that calculates a suction flow rate according to a predetermined calculation formula using output signals of an inlet temperature detector, a discharge pressure detector, and a rotation speed detector. Compressor surging prevention device described in . 7. The above-mentioned suction flow rate detection means is provided with a "differential pressure converter that detects the differential pressure between the total pressure and the static pressure" at the compressor inlet, and also has "an output signal of the above-mentioned differential pressure converter and a predetermined Claim 5 is characterized in that the device is provided with a "differential pressure type flow rate calculator" which calculates the suction flow rate based on the correction coefficient.
Compressor surging prevention device described in Section 1. 8. A claim characterized in that the compression control device is equipped with an alarm means that is activated when at least one of the power change rate and the power equivalent amount change rate approaches a limit value. The surging prevention device for the compressor described in item 5. 9. The compressor surging prevention device as set forth in claim 5, wherein the compressor division position is a bleed position of the compressor.