JPS6397898A - Clearance adjusting device of axial compressor - Google Patents

Abstract

PURPOSE:To improve the efficiency of a compressor by enlarging the opening of a flow regulating valve provided in the midway of an air intake pipe, when the circumferential clearance value between an inner casing and a rotor blade end has been enlarged. CONSTITUTION:A clearance between an inner casing 1a and the end of a rotor blade 4 is detected by clearance measuring devices 22-24 that the clearance is enlarged beyond the set value and the valve opening degrees of flow regulating valves 18-20 are enlarged. Adjusting air is led into air chambers 11-13 through intake pipes 15-17, increasing the heat elongation percentage of a casing 1 and lessening the elongation difference in the axial direction between the casing 1 and a rotor 3. Thereby, the clearance between the casing and the rotor blade end will not enlarge during the operation, thus resulting in the improvement of the efficiency of a compressor.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a gap adjustment device for an axial flow compressor, and in particular, the present invention relates to a gap adjustment device for an axial flow compressor. The present invention relates to a gap adjustment device for a multistage axial flow compressor that adjusts the gap between a stationary body and a blade tip by controlling the amount.

(Prior Art) Generally, as shown in FIG. 5, a multi-stage axial flow compressor has bearings 5 at both ends inside a tapered casing 51.
2.52 is rotatably incorporated therein. A plurality of stationary blades 5 are provided on the inner periphery of the casing 51.
5 is fixedly installed, and the rotor blades 56 implanted in the rotor 53 are arranged so as to be located between the stator blades 55, and the intake air from the compressor 57 is transferred to Dm55 and the rotor blades 56. The compressed air is gradually compressed between 56 and 56, and is discharged from the compressor outlet 58 as high-temperature, high-pressure compressed air. Since the rotor 53 receives a thrust load during the compression stroke, a thrust bearing 59 is provided on the compressor outlet 58 side.

As shown in FIGS. 6 and 7, the tips of the rotor blades 56 are formed to be inclined toward the discharge side along the shape of the tapered casing 51. Structurally moving blade 5
A gap g is formed between the tip of the compressor 6 and the casing 51, but if this gap g is too large, the amount of leakage will increase, causing a decrease in the efficiency of the compressor. Therefore, during design, consideration is given to making the gap g as small as possible.

(Problem to be Solved by the Invention) However, when an axial flow compressor is operated, high heat is generated when compressing air, and this heat causes the casing 51 and rotor 53 to thermally expand and extend in the axial direction. Become.

The coefficient of thermal expansion of the casing 51 is generally smaller than that of the rotor 53, resulting in a difference in the amount of expansion between the two. As is clear from FIG. 8, this difference in elongation becomes noticeable when the axial flow compressor is started up.

However, in the conventional axial flow compressor, even if the gap g is made as small as possible at the time of design as shown in FIG.
If the above-mentioned difference in the amount of elongation occurs, there is a problem that the gap g becomes large as shown in FIG. 6 at the time of startup, the amount of leakage increases, and the efficiency of the compressor decreases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the conventional technology described above, to prevent the phenomenon in which the gap increases due to the difference in the amount of thermal expansion in the axial direction during operation, and to An object of the present invention is to provide an axial flow compressor that can improve efficiency.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a casing that is double formed of an outer casing and an inner casing and defines an air chamber between them, and a casing that is formed in the inner casing. a slit that communicates the air chamber and the compressed air passage;
a gap measuring device for detecting a gap value in the circumferential direction between the inner casing and the tip of the rotor blade; an introduction pipe for introducing adjusted air into the air chamber; and a gap measuring device installed on the introduction pipe. The flow f whose valve opening degree is increased or decreased according to the detected value of
It is characterized by being equipped with an fi adjustment valve.

(Function) Based on the above configuration, the present invention will be described in detail. When the gap value in the circumferential direction between the inner casing and the tip of the rotor blade increases to exceed the value at the time of design during operation, the gap measuring device detects this, and based on this detected value, the valve opening of the flow rate regulating valve is increased, and warmed regulated air is introduced into the air chamber. As a result, the casing becomes hotter than the rotor, the thermal elongation of the casing and rotor become almost equal, and the gap value in the circumferential direction between the casing and rotor approaches the design value. This is because the casing has a smaller coefficient of thermal expansion than the rotor. On the other hand, when the gap value decreases from the design value, the gap measuring device detects this, and based on this detected value, the valve opening of the flow rate adjustment valve is decreased, and finally the introduction pipe is closed. . The warmed conditioned air then flows out into the compressed air passage through the slit, thereby
The temperatures of the casing and rotor become approximately equal, and due to the difference in coefficient of thermal expansion between the casing and rotor, a difference in thermal expansion occurs between the casing and the rotor, and the gap value in the circumferential direction between the casing and the tip of the rotor blade increases. Therefore, the gap value approaches that at the setting of 1.

(Example) Hereinafter, an example of a gap adjustment device for an axial flow compressor according to the present invention will be described with reference to FIG.

Reference numeral 1 indicates a casing, and the casing 1 is composed of an inner casing 1a formed in a tapered shape and a cylindrical outer casing 1b disposed so as to surround the inner casing 1a.

A plurality of stator blades 2 are fixedly installed on the inner periphery of the inner casing 1a in a similar configuration to the conventional one, and a rotor 3 is installed between the stator blades 2.
A rotor blade 4 implanted in the rotor blade 4 is arranged. The rotor 3 is supported at both ends by bearings 5.5, and is rotatable within the inner casing 1a via a drive device (not shown). When the rotor 3 rotates, the air sucked from the compressor 6 is The compressed air, which is gradually compressed between the stationary blades 2 and the moving blades 4 and becomes high temperature and high pressure, is discharged from the compressor outlet lower. Further, since the rotor 3 receives a thrust head ball during the compression stroke, a thrust bearing 8 is provided on the compressor output lower side.

According to the present invention, three annular air chambers 11, 12, and 13 are formed inside the inner casing 1a and the outer casing 1b. Warmed or cooled conditioned air is introduced into the air chambers 11, 12.13 through inlet pipes 15, 16, 17 attached to the outer casing 1b. Flow rate adjustment valves 18, 19.20 that can be opened and closed are installed on the inlet pipe 15, 16, 17, and the flow rate 5
! The valve opening degrees of the regulating valves 18, 19, 20 are increased or decreased in accordance with the detected values at the gaps 22, 23, 24. The gap measuring device 22゜23.24 is inserted through the outer casing 1b and the inner casing 1a, and its measuring end is placed inside the inner casing 1a at a position facing the tip of the rotor blade 4. There is.

The inner casing 1a also has air chambers 11°, 12.
13 and the compressed air passage 25 are connected to each other.
7.28.29 are formed.

Next, the operation of the present invention will be explained with reference to FIGS. 1 to 3.

When the axial compressor is started, the temperature of the compressed air rises rapidly, and the casing 1 and rotor 3 undergo thermal expansion in the axial direction due to this heat.

When the thermal expansion starts, the thermal expansion of the rotor 3 is larger than that of the casing 1, and the rotor 3 is attached to the thrust bearing 8.
It extends toward the compressor population 6 side from the base point. When the rotor 3 expands, the state of the inner casing 1a and the moving blade 4 moves relatively from the state shown in FIG. 3 to the state shown in FIG. 2, and the gap g between the inner casing 1a and the tip of the moving blade 14 increases as the amount of relative movement increases.

According to the present invention, the gap MJ constant device 22°23.24 can be used to detect that the gap g has increased beyond a certain set value.
is detected, and based on this detected value, the flow rate regulating valves 18, 19
．． 20 valve openings are increased.

At this time, the conditioned air introduced through the inlet pipes 15, 16, 17 is warmed high temperature air.

The warming air enters the air chamber 11.12.13,
This heat increases the thermal elongation 2 of the casing 1, reduces the difference in axial elongation between the casing 1 and the rotor 3, and
The state shown in the figure is approached.

Therefore, the gap g can be made close to the designed gap.

On the other hand, when the gap g becomes smaller than a certain set value, the gap measuring devices 22, 23, 24 detect this, and based on this detected value, the valve opening of the flow rate regulating valve 18° 19.20 is determined. is reduced and finally closes the inlet tube 15, 16, 17.

The warming air in the air chamber 11.12.13 then flows through the slits 27.28.29 into the compressed air passage 26.
The temperature inside the air chamber 11, 12, 13 becomes approximately equal to the temperature on the compressed air passage 25 side. As a result, the casing 1 shrinks and the gap g can be brought closer to the designed gap.

FIG. 4 shows another embodiment of the present invention, in which the upstream ends of the introduction pipes 15, 16, and 17 are opened into the high-pressure stage of the axial flow compressor.

With this configuration, the above-mentioned gap g can be adjusted using a portion of the high-temperature compressed air, and the structure can be made compact.

In the embodiment described above, three air chambers 11, 12 and 13 were formed, but according to the present invention, it is also possible to have one air chamber, and it is possible to divide the air chamber into one. It is also possible to arbitrarily select whether to form the

〔Effect of the invention〕

With the above configuration, according to the present invention, the gap between the casing and the tip of the rotor blade does not increase during operation, and the efficiency of the axial flow compressor can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the gap adjustment device for an axial flow compressor according to the present invention, FIGS. 2 and 3 are longitudinal sectional views showing an enlarged tip of the rotor blade, and FIG. The figure is a longitudinal sectional view showing another embodiment according to the present invention, FIG. 5 is a longitudinal sectional view of a conventional axial flow compressor, and FIGS. 6 and 7 are longitudinal sectional views showing enlarged tips of the rotor blades. The plan view and FIG. 8 are diagrams showing the elongation of the rotor and casing at the time of startup. 1... Casing, 1a... Inner casing, 1b
...Outer casing, 2... Stator blade, 3... Rotor, 4... Moving blade, 11, 12.13... Air chamber, 15
．． 16゜17...Introduction pipe, 18.19.20...
Flow rate adjustment valve, 25... Compressor passage, 27, 28.29
...slit, g...gap. Applicant's agent Sato - Yuba 1 Figure 1 Tail 2 Figure Color 3 Figure 4 Figure Otsu 6 Figure Otsu 7 Figure Island 8 Figure

Claims (1)

[Scope of Claims] 1. A casing that is double formed of an outer casing and an inner casing and defines an air chamber between them, and a slit that is formed in the inner casing and communicates the air chamber with a compressed air passage. , a gap measuring device for detecting a gap value in the circumferential direction between the inner casing and the tip of the rotor blade, an introduction pipe for introducing adjusted air into the air chamber, and the gap measuring device incorporated on the introduction pipe. A gap adjustment device for an axial flow compressor, comprising a flow rate adjustment valve whose opening degree is increased or decreased in accordance with a detected value. 2. The gap adjustment device for an axial flow compressor according to claim 1, wherein the upstream end of the introduction pipe is opened into a high pressure side stage of the axial flow compressor.