JP3758835B2 - Clearance control method by cooling air compressor disk - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a clearance control method by cooling an air compressor disk, ventilates air by flowing it through the disk, reduces the clearance during start-up and steady operation, and the temperature difference between the disk outer peripheral side and the inner peripheral side. Is reduced to reduce thermal stress.
[0002]
[Prior art]
In a gas turbine plant, air from a compressor is guided to a combustor, and high-temperature combustion gas generated by combustion with fuel is guided to the gas turbine, the gas turbine is driven, and a part of the air is extracted to extract the gas turbine. They are guided to the stationary and moving blades to cool them. FIG. 8 is a general cross-sectional view of a connecting portion between such a compressor and a gas turbine. The compressor 1 includes a stationary blade 1-1 fixed to a casing 8 on the fixed side, and a disk 2 on the rotor side. Are attached in the circumferential direction and are alternately arranged in the axial direction, and the rotor rotates to discharge the compressed air 40.
[0003]
The compressed air 40 from the compressor 1 is guided to a combustor (not shown) and used for combustion, and the combustion gas flows between the stationary blades 5-1 and the moving blades 5-2 of the gas turbine and expands to become a rotor. , And a part of the air 41 is guided from the air separator 7 to the gas turbine side and supplied as sealing air between the stationary blade 5-1 and the moving blade 5-2, and also to the moving blade 5-2. It guide | induces and cools the moving blade 5-2, and the air after cooling is discharge | released to a combustion gas channel | path.
[0004]
In the compressor of the gas turbine described above, the clearance between the moving blade 1-2 and the casing 8 is kept at a predetermined gap to avoid contact at the time of start-up. The clearance also changes due to the thermal elongation of the gas, reaches the minimum clearance on the way, and gradually increases during steady operation. When the clearance during the steady operation becomes too large, the performance of the compressor is reduced.
[0005]
FIG. 9 is a cross-sectional view of an aircraft engine, which employs a structure in which the clearance between the moving blade and the casing is reduced when the engine is started to prevent surging that occurs when the clearance is large. (A) is the sectional drawing, FIG.9 (b) is XX sectional drawing in (a). In the figure, 50 is a casing, 51 is a moving blade, and has a clearance d between the casing 50 and the casing 50. 52 is a disk, 53 is a rotor, and the disk 52 is provided with a plurality of holes 54, 55, 56 through the cavities 57-1, 58-1, 59-1 equally in the circumferential direction. The cavities 57-1 to 59-1 and 57-2 to 59-2 are communicated with each other.
[0006]
The aircraft engine having the above-described configuration has air 60 having an appropriate temperature at the time of startup through the cavities 57-1, 57-2, 58-1, 58-2, 59-1, 59 through the holes 54, 55, 56 as indicated by arrows. -2 is used to warm the rear stage of the disk 52, keeping the clearance between the moving blade 51 and the casing 50 at the start small, and maintaining the performance of the engine at the start.
[0007]
[Problems to be solved by the invention]
As described above, the conventional gas turbine compressor has a relatively low pressure ratio, and the compressor rear stage has a relatively low temperature. Recently, there is a tendency to increase the pressure ratio. As a result, a high-strength material is adopted, resulting in high costs and a long-life design in terms of strength is becoming difficult.
[0008]
Also, in aircraft engines, there is an example in which air is supplied to the disk to warm up and the clearance at startup is kept small in order to ensure startup performance. The clearance control method for compressors that can be operated with as little clearance as possible during steady state operation is still generally applicable. The current situation is not.
[0009]
Especially in the compressor in the gas turbine plant, since the cooling structure is not adopted, the performance of the compressor affects the efficiency of the entire gas turbine plant when the long life design by reducing the thermal stress by cooling is performed. It is strongly desired to improve the performance of the compressor by keeping the clearance small from the start of the compressor to the steady operation.
[0010]
Therefore, in the present invention, the cooling blade is cooled by flowing cooling air through the disk at the rear stage of the compressor, and the clearance is reduced from the start to the steady operation by controlling the air temperature. It is an object of the present invention to provide a clearance control method by cooling an air compressor disk that is operated and supplied to the stationary blades and moving blades of the gas turbine after cooling the disk and used for sealing and cooling. .
[0011]
[Means for Solving the Problems]
The present invention provides the following means (1) and ( 2 ) to solve the above-mentioned problems.
[0012]
(1) A part of the discharge air from the compressor is extracted and guided to a cooler, cooled to a predetermined temperature, and then circulated into a cavity at the rear stage of the rotor disk of the same compressor to cool the disk, and the rotor blades on the outer periphery of the disk controlling the clearance between the tip and the casing, together with the air after the disc cooling leads to the gas turbine via an intermediate shaft which connects the gas turbine the compressor, and supplies the sealing and moving blade cooling air, the A clearance control method by cooling an air compressor disk, wherein cooling of air by a cooler is performed for a predetermined time from the start of startup .
[0014]
( 2 ) In the invention of the above (1), the clearance between the casing and the moving blade is set in advance so as to be within an allowable value of the minimum clearance generated after startup, and the disk is cooled during startup to cool the disk. A clearance control method by cooling an air compressor disk, wherein an allowable value of a minimum clearance is maintained and a clearance during steady operation is also maintained at a predetermined value.
[0015]
At the rear stage of the disk of the high pressure ratio compressor, the temperature of the discharged air becomes as high as 450 to 500 ° C., and the outer periphery of the disk is rapidly heated at the start-up, resulting in a large temperature difference between the outer periphery and the inner periphery of the disk. Thermal stress increases, and it is necessary to use a high-strength material. In addition, the clearance between the casing and the moving blades at the time of starting is set to be large so that contact at the minimum clearance due to thermal elongation is avoided, and therefore the clearance during steady operation must be large. In (1) of the present invention, air is cooled by a cooler, and the cooled air is allowed to flow through a compressor disk for ventilation to cool the rear stage of the disk. For this reason, the heat on the outer peripheral side of the disk is carried to the inner peripheral side and the disk is cooled, so that the temperature difference between the outer peripheral side and the inner peripheral side of the disk is reduced, and the thermal stress is reduced. If the thermal stress is reduced, it is not necessary to use a high-strength material, which leads to cost reduction.
[0016]
Further, by cooling the second part is a high temperature portion of the disk, suppressing thermal expansion of the disc back stage, the minimum clearance is formed between leading to the steady operation from the start, the air cooled by the cooler between this By cooling and cooling the rear stage of the disc, the minimum clearance is increased, contact is avoided, and the response of elongation to the steady state of the disc is accelerated so that efficient and safe operation can be performed in the unsteady state. become.
[0017]
In ( 2 ) of the present invention, when the rear stage of the disk is cooled by the air cooled by the cooler, the thermal expansion of the disk is suppressed, but the cooling capacity of the cooler is increased and the thermal elongation is reduced particularly at the initial stage of starting when the minimum clearance occurs. In this way, the clearance from the casing side can be preliminarily set to be small by an amount corresponding to the decrease in the thermal elongation. Thus, even if the initial clearance is set small, contact at the minimum clearance can be avoided and the clearance can be kept small even during steady operation.
[0018]
In the present invention, the air that has further cooled the disk can be sent to the gas turbine side and used as the sealing air for the gas turbine and the air for cooling the rotor blades, so that the air that has cooled the compressor can be used effectively.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a system diagram of a gas turbine to which a clearance control method by cooling an air compressor disk according to the present invention is applied. In the figure, 1 is a compressor and 2 is a disk of the compressor 1. A combustor 3 combusts air and fuel from the compressor to generate high-temperature combustion gas. Reference numeral 4 denotes a gas turbine, which has a stationary blade / moving blade 5 therein, guides high-temperature combustion gas generated in the combustor 3, rotates a rotor, rotates a generator, and generates power. Reference numeral 6 denotes a cooler, which partially extracts air discharged from the compressor 1 and cools it to a predetermined temperature, sends it to the rear stage side of the compressor 1, ventilates the disk, and cools it.
[0020]
FIG. 2 is a sectional view of a compressor disk to which the clearance control method according to the embodiment of the present invention is applied. In the figure, the disk 2 of the compressor 1 is provided with two cavities 11, 12 three places, 13 three places arranged in the axial direction, and the cavities 11 are provided with holes 22 and 23. The two cavities 11 in the axial direction communicate with each other. Holes 21, 27, and 28 are provided in the cavity 12 and communicate with each other in the axial direction, and communicate with the cavity 11 through holes 24, 25, and 26. Similarly, the cavity 13 communicates with the cavity 12 through the holes 29, 30, and 31, and also communicates with the holes 32 and 33 in the axial direction.
[0021]
In the compressor having the above-described configuration, a part of the air cooled by the cooler 6 enters the compressor 1 and flows out between the moving blades and stationary blades of the subsequent stage, and is supplied as a seal for high-temperature compressed air. , Flows into the holes 22, 23, enters the cavity 11, and enters the cavity 12 through the holes 24, 25, 26. Air also flows into the cavity 12 from the hole 21, flows into the cavity 13, and in the process of flowing through these, the rear stage of the disk 2 is cooled and passes through the holes 33 and 32 to carry the heat on the outer periphery of the disk to the inner periphery. , Flows out to the intermediate shaft portion 34.
[0022]
The air flowing out to the intermediate shaft part 34 passes through the bore part and flows to the gas turbine side, and is supplied as sealing air between the stationary blade 5-1 and the moving blade 5-2 and cooling air for the moving blade 5-2. Is done. Part of the air from the compressor 1 flows into the rotor blade 5-2 from the air separator 7 and is supplied for cooling. The air obtained by cooling the rear stage of the disk 2 of the compressor 1 with this cooling air. Are combined and supplied to the rotor blade 5-2.
[0023]
3A and 3B are views showing a conventional state in which the disk 2 is not cooled. FIG. 3A is a cross-sectional view thereof, and FIG. 3B is a view showing a temperature difference between the outside and the inside of the disk 2. In (a), when the outer side is A and the inner side B, the outer side A has a higher temperature, and the inner side B has a lower heat transfer coefficient, so the temperature is lower. This state is shown in (b). Since the heat transfer coefficient to B is small between A and B, a temperature difference is generated between A and B.
[0024]
4A and 4B are views showing the state of the present invention in which the disk is cooled, wherein FIG. 4A is a cross-sectional view of the disk, and FIG. 4B is a view showing a temperature difference between the outer side and the inner side of the disk 2. In (a), the cooling air 30 is ventilated and cooled through a hole provided in the disk, whereby the heat on the disk outer peripheral side is exchanged inward and the heat transfer coefficient is improved. The temperature difference with B ′ is smaller than that of the conventional disk shown in FIG. This state is shown in (b), and the temperature difference between A ′ and B ′ comes closer to that in FIG. 3 (b).
[0025]
FIG. 5 is a diagram showing the characteristics of the cooler 6 that cools the air from the compressor shown in FIG. 1. The air temperature on the discharge side of the compressor is about 450 to 500 ° C. Cool to about 200-250 ° C. During the cooling process, during the compressor operation, during the time period T until the clearance between the casing and the moving blades becomes the minimum, the cooler capacity is controlled to be maximized and the temperature is lowered. , The cooling capacity is controlled to be 200 to 250 ° C.
[0026]
FIG. 6 is a diagram showing the radial extension of the rotor blade tip when the cooler is operated with the characteristics described in FIG. 5, with the solid line indicating the casing extension characteristic and the alternate long and short dash line when the cooling air does not flow. The characteristics of elongation of the blade tip, and the dotted line are the characteristics of elongation of the blade tip when cooling air flows. In the case of not cooling (the alternate long and short dash line), the elongation is increased by the action of centrifugal force in the initial stage of operation, and there is a risk of contact unless the clearance with the casing is increased. Cooler and cooled to ON at this time, the feed cooling air according to the characteristics shown in FIG. 6, when cooled by Ride disc to ventilate the disc 2, a characteristic as shown by a dotted line. Therefore, the extension of the blade tip can be suppressed during a period when the clearance between the casing and the blade tip is severe, and as a result, the minimum clearance (MCL) can be maintained.
[0027]
Cooling with a cooler is a method of turning on the cooler and flowing the cooled air while the elongation of the rotor part increases due to centrifugal force from the start of operation, and suppressing the expansion during this time, and then turning it off to turn the rotor side into a steady stretch state There is a method of making the cooler strong during the period when the centrifugal force is applied and increasing the elongation, then cooling the air for a predetermined period of time and then gradually turning it off and gradually turning it to a steady state. .
[0028]
FIG. 7 is a diagram showing the effect when the clearance between the casing and the blade tip is controlled by the method described above. FIG. 7A shows the relationship between the radial extension of the casing and the blade tip, and FIG. Indicates the effect of controlling the clearance. In (a), when there is no cooling of the rotor blade, the extension characteristic of the rotor blade tip reaches the minimum clearance MCL between the casing and the disk by the action of centrifugal force after startup, and then the clearance gradually increases in the steady state. The clearance CL ₁ between the casing and the casing becomes stable.
[0029]
When cooling air is passed through the disk and cooling as described with reference to FIG. 6 is performed, the tip of the rotor blade has the characteristics indicated by the dotted line, the response to the steady state is accelerated, and the minimum clearance is increased by δ _1. , MCL + δ ₁ , the elongation increases by δ ₂ even during steady state, and the clearance during steady operation becomes CL ₁ + δ ₂ , which is slightly wider. However, the cooling characteristics at this time are controlled so that δ ₁ > δ ₂ .
[0030]
Therefore, as shown in (b), when the initial set value of the casing is packed by δ _{1 and} set as indicated by a two-dot chain line, the relationship between the clearance between the casing and the blade tip is indicated by the two-dot chain line and the dotted line in the figure. It becomes the relationship. In such a relationship, when the minimum clearance occurs without cooling, the gap can be filled up to the minimum point that does not contact, the minimum clearance moves like MCL ′, and the clearance in the steady state is CL _1. It changes to CL ₂ from.
[0031]
The clearance CL ₂ is reduced by (−δ ₁ + δ ₂ ) from CL _{1 in} the original state. As a result, the air from the compressor 1 is extracted and cooled by the cooler 6, and the compressor disk 2 By flowing in the latter stage and ventilating and cooling this part, the clearance at the initial stage of starting can be filled by δ ₁ , and the clearance during steady operation is (−δ ₁ + δ compared to when cooling is not performed). ₂ ) can only be made smaller.
[0032]
As described above, the disk is cooled with air, and the clearance at the time of starting and at the time of steady state can be made smaller than before, so that the efficiency is improved. Furthermore, the thermal stress can be reduced because the temperature difference between the outer periphery and the inner periphery of the disk 2 at the time of startup is reduced, lower materials are applicable it is possible to reduce the cost, and can be long-life design Become.
[0033]
【The invention's effect】
The clearance control method by cooling the air compressor disk of the present invention extracts a part of the discharge air of the compressor, guides it to the cooler, cools it to a predetermined temperature, and then distributes it in the cavity at the rear stage of the rotor disk of the compressor The disk is cooled to control the clearance between the rotor blade tip on the outer periphery of the disk and the casing, and the air after cooling the disk is guided to the gas turbine through an intermediate shaft connecting the compressor and the gas turbine for sealing. And cooling blade air is supplied , and air cooling by the cooler is performed for a predetermined time from the start. By such a method, the heat on the outer periphery side of the disk can be carried inward, the metal temperature of the disk can be made uniform, and the thermal stress of the disk can be reduced. Therefore, the design can be performed without using a high-strength material and the cost can be reduced.
[0034]
( 2 ) of the present invention is that the clearance between the casing and the moving blade in the above (1) is set in advance so as to be within an allowable value of the minimum clearance generated after startup, and the disk is cooled at startup. Thus, an allowable value of the minimum clearance is maintained and a clearance during steady operation is also maintained at a predetermined value.
[0035]
In this way, the air cooled by the cooler reduces the thermal stress of the disk and increases the cooling capacity of the cooler to reduce the thermal elongation, especially at the beginning of the start when the minimum clearance occurs. It is possible to set the clearance with the casing side by a predetermined amount so as to be small. Thus, even if the initial clearance is set small, contact at the minimum clearance can be avoided and the clearance can be kept small even during steady operation.
[0036]
Furthermore, in the present invention, the air that has cooled the disk is sent to the gas turbine side and can be used as sealing air for the gas turbine and air for cooling the blades. it can.
[Brief description of the drawings]
FIG. 1 is a system diagram to which a clearance control method by cooling an air compressor disk according to an embodiment of the present invention is applied.
FIG. 2 is a cross-sectional view of a compressor to which a clearance control method by cooling an air compressor disk according to an embodiment of the present invention is applied.
FIGS. 3A and 3B show a temperature state when the air compressor disk is not cooled; FIG. 3A is a cross-sectional view of the disk, and FIG.
4A and 4B show a temperature state during cooling of the air compressor disk, where FIG. 4A is a cross-sectional view of the disk, and FIG. 4B is a diagram showing a temperature state on the outer side and the inner side of the disk.
FIG. 5 is a diagram showing cooling characteristics of a cooler in a clearance control method by cooling an air compressor disk according to an embodiment of the present invention.
FIG. 6 is a diagram showing a relationship between a casing and a moving blade in a clearance control method by cooling an air compressor disk according to an embodiment of the present invention.
7A and 7B show characteristics to which a clearance control method by cooling an air compressor disk according to an embodiment of the present invention is applied, and FIG. The figure which shows the state of (b) is a characteristic view when the clearance before starting of a casing is filled.
FIG. 8 is a cross-sectional view of a conventional air compressor.
FIG. 9 is a cross-sectional view of a conventional aircraft engine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Compressor 2 Disc 3 Combustor 4 Gas turbine 5 Stator blade, moving blade 6 Cooler 11, 12, 13 Cavity 21-33 Hole 30 Cooling air 34 Intermediate shaft part

Claims (2)

A part of the compressor discharge air is extracted and guided to a cooler, cooled to a predetermined temperature, and then circulated in a cavity at the rear stage of the rotor disk of the same compressor to cool the disk. The air after cooling the disk is guided to the gas turbine through an intermediate shaft connecting the compressor and the gas turbine, and is supplied as sealing air and cooling blade cooling air. The clearance control method by cooling the air compressor disk, wherein the cooling of the air compressor is performed for a predetermined time from the start of startup . The clearance between the casing and the rotor blades is set in advance so that the minimum clearance generated after startup is within the allowable value, and at the time of startup, the disc is cooled to maintain the allowable value of the minimum clearance, and the steady operation is performed. 2. The clearance control method by cooling the air compressor disk according to claim 1 , wherein the clearance at the time is also maintained at a predetermined value .

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