JP2010112276A - Turbine moving blade structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable turbine moving blade structure for providing the high damping effect, by keeping a connecting structure with adjacent blades even when exposed to high pressure-high temperature steam like a high pressure turbine initial stage moving blade. <P>SOLUTION: This turbine moving blade structure is assembled by inserting a turbine moving blade having a blade profile part 1, a cover part 2, a platform part 3 and two or more of blade groove parts 4, from the turbine shaft direction into a blade groove formed in a disc part 5 of a turbine rotor. The blade profile part 1 has a blade profile twisted over the blade tip from the blade root, and the mutual adjacent blades are contacted and connected on a peripheral directional surface of the platform part 3 and a peripheral directional surface of the cover part 2 so that the cover part 2 forms one ring when viewed from the outer periphery. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a turbine blade structure, and more particularly, to a blade structure of a first-stage blade of a high-pressure turbine or a first-stage blade of an intermediate-pressure turbine that is exposed to a high pressure of 25 MPa or more and a high temperature of 600 ° C. or more.

  Generally, a high-pressure first stage moving blade of a steam turbine is exposed to high-temperature and high-pressure steam flowing from a boiler, and is accompanied by large fluctuations and pulsation flows. Therefore, a rigid connection structure is desired between the turbine moving blade and the disk.

  One of the steam turbine blade structures is a blade structure disclosed in Patent Document 1. The blade structure shown in Patent Document 1 has a blade profile that maintains the same shape from the blade root to the blade tip, and is inserted into the disk portion of the turbine rotor in the axial direction in order to increase the rigidity of the blade groove structure. Two blade groove structures are provided in one rotor blade.

  In this wing structure, generally, a hood and a tenon are provided at the top of the wing tip, and the shroud cover and the wing are connected by caulking the tenon. In this blade connection, approximately four group blade structures are formed. This blade structure has a structure with sufficient strength against force acting in the centrifugal direction and circumferential direction.

  On the other hand, as the turbine output increases, the turbine must increase the ring zone area, so the blade length needs to be increased. However, as the blade length increases, the blade rigidity decreases, making it difficult to ensure the strength to withstand high pressure steam. For this reason, conventionally, a structure in which the steam inlet is divided into two in the axial direction is adopted, and by configuring two first stage paragraphs, when the turbine output is large without increasing the blade length of the first stage rotor blades. I try to deal with it.

Japanese Examined Patent Publication No. 61-48608

  The turbine blade structure with the shroud cover and caulking the tenon is strongly constrained by the shroud cover, but it is exposed to high-temperature and high-pressure steam flowing in from the boiler. In contrast, there is a case where the damping effect is small and an excessive response is shown. If the turbine output is large and the turbine structure with two steam inlets divided in the axial direction is not adopted, it is necessary to make the first stage rotor blade longer. Therefore, it becomes difficult to ensure the strength to withstand high-temperature and high-pressure steam.

  In addition, when a turbine structure with two steam inlets in the axial direction is adopted, the axial length of the turbine becomes longer and the axial span of the entire turbine structure increases, so that not only the first stage blades but also the structure of the turbine building itself Need to be larger. There is also a problem that the flow becomes complicated by dividing the flow into two.

  An object of the present invention is to provide a highly reliable turbine rotor blade structure that maintains a connection structure with adjacent blades even when exposed to high-pressure and high-temperature steam, and that provides a high damping effect.

  In order to achieve the above object, in the present invention, a blade profile of a turbine blade is formed from a blade root to a blade tip to a twisted blade in consideration of a three-dimensional flow. The circumferential surface of the cover part and the platform part is contact-connected so as to form one ring.

  It is desirable that the circumferential surface where the blade groove portion and the blade groove of the disk portion contact, the circumferential surface of the adjacent platform portion, and the circumferential surface of the cover portion have an angle inclined with respect to the turbine axial direction.

  Further, it is desirable to insert pins into the circumferential surface where the blade groove portion and the blade groove of the disk portion are in contact, the circumferential surface surface of the adjacent platform portion, and the circumferential surface surface of the cover portion, and to contact and connect each with the pin. .

    Further, it is desirable that the pins of the cover part and the pin of the blade groove part are parallel.

  Moreover, it is desirable that the pins inserted between the circumferential surfaces of the cover part (both ends in the circumferential direction of the cover part) have a taper angle of tan α = 1/20 to 1/40.

  Further, the material of the pin inserted into the cover part and the blade groove part is preferably a cast material having a higher linear expansion coefficient than the material of the turbine rotor blade.

  According to the present invention, blade rigidity can be increased, and even when exposed to steam at high pressure and high temperature (for example, 25 MPa, 600 ° C. or higher), the connection structure with adjacent blades is maintained, and a high damping effect is obtained. A highly reliable turbine blade is provided.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration diagram of a turbine rotor blade of the present invention. The turbine blade includes a blade profile part 1, a cover part 2, a platform part 3, and a blade groove part 4.

  The blade profile part 1 of the turbine blade corresponds to the increase in the blade length of the first stage blade of the high-pressure turbine, and the blade length is at least 50 mm. Considering the three-dimensionality of the flow, the blade profile as shown in FIG. It has the external shape. That is, the blade profile part 1 is composed of twisted blades. Except for twisting, the shape and size of the blade root and the blade tip are substantially the same. Two blade groove portions 4 are provided in the platform portion 3. By inserting the blade groove portions 4 in the axial direction of the turbine with respect to the blade grooves formed in the disk portion 5 of the turbine rotor, the turbine rotor blades are formed. Built into the turbine rotor.

  In addition, the circumferential surface of the platform portion where the blade grooves are present and the circumferential surface of the cover portion are in contact with those of adjacent blades, so that the disk portion and the turbine blade are connected to each other. Structure.

  FIG. 3 shows the blade structure (connection structure) of the present invention viewed from the outer periphery. When the cover portion 2 at the tip of the blade is contact-connected, the cover portion 2 forms one ring as viewed from the outer periphery. In FIG. 3, reference numeral 10 denotes a turbine rotor.

  In the wing structure of the present invention, in the case where a contact connection that retains a certain degree of contact force is configured on the circumferential surface of the platform portion and the cover portion, the circumferential direction of the wing cover that is inserted last among all the wings It is desirable to design the pitch a little wider than the pitch on the drawing, and to spread the wing cover already built into the disk and to connect them together.

  In the wing structure of the present invention, both the cover portion and the platform portion are contact-connected and configured as one ring on the entire circumference, so that the rigidity is higher and the damping effect is higher than the conventional one. In addition, in contrast to the vibration characteristic in which the circumferential primary bending vibration mode peculiar to the group blade structure is generated by the conventional tenon-shroud cover connection, the circumferential primary bending vibration is achieved by the achievement of the all-round one-ring blade structure. Since the natural frequency of the mode is an extremely high value and the resistance of the cover to bending in the circumferential direction is increased, the resonance stress in the circumferential primary bending vibration mode is significantly reduced.

  Compared to the conventional group blade structure, the all-round one-ring blade structure formed by the blade structure of the present invention has a simplified vibration mode and is defined by multiplying the number of stationary blades by the number of rotations. There is an advantage that the nozzle resonance frequency can be easily avoided. In addition, in the structure where the tenon is caulked, the periphery of the tenon part is a stress concentration part, and special consideration is required in terms of strength. However, in the wing structure of the present invention, such consideration is not required and the strength is damaged. It is a difficult structure.

  FIG. 4 shows a schematic view of the steam inlet of a high-power high-pressure turbine to which the turbine rotor blade of the present invention is applied. Reference numeral 11 is an outer casing, 12 is a main steam pipe, 13 is a nozzle box, 14 is an inner casing, 15 is a stationary blade, 31 is a second stage moving blade, and 35 is a second stage stationary blade. Conventionally, a structure in which the steam inlet is divided into two in the axial direction is adopted, and two first stage paragraphs are configured to cope with a case where the turbine output is large without increasing the blade length of the first stage rotor blade. However, in the high-power type high-pressure turbine to which the steam turbine rotor blade of the present invention is applied, a turbine blade having a longer blade length is used, and there is one steam inlet in the axial direction. That is, if the blade structure of the present invention is used, a high rigidity and high damping structure can be obtained even if the blade length is long. Therefore, as shown in FIG. Thus, a normal high-pressure steam turbine structure constituting the second stage can be formed on the downstream side.

  Next, another embodiment of the present invention will be described in detail with reference to FIG.

  In this embodiment, a contact pin 6 is used. As shown in FIG. 5, the contact pin 6 is provided between the blade groove portion 4 and the blade groove of the disk portion 5, and the platform portion 3 between adjacent blades. And the cover portion 2 are interposed between the surfaces (circumferential surfaces) to be contacted. The contact pin 6 is exposed to high-temperature and high-pressure steam flowing in from the boiler, and generates friction against shear force and slip against contact surface pressure with respect to excitation force due to transient fluid force accompanied by large fluctuations and pulsation flow. The action is expected to act as a shock absorber against excessive force action.

  It is expected that the contact coupling force between adjacent wings by the contact pin 6 is improved by a relative difference in centrifugal force, for example, by changing the specific gravity of the pin material and the specific gravity of the wing material.

  According to the present embodiment, the effect of the embodiment shown in FIG. 1 can be obtained in the same manner, and the contact force due to high temperature creep can be improved as compared with the structure in which the forcible contact coupling force is provided to realize the all-around one ring blade. There is an advantage that the problem of relaxation is eliminated.

  In the present embodiment, the contact pin 6 is a surface (circumferential surface) between the blade groove 4 and the blade groove of the disk portion 5 and the surface of the platform portion 3 and the cover portion 2 between the adjacent blades. Although intervening between them, the contact pin is used only in any part, and the part where the contact pin 6 is not used is forcibly applied with contact connection force as in the embodiment of FIG. It is also possible to make it.

  Next, the contact pin 6 will be described in detail with reference to FIG.

  The contact pin 6 is tapered as shown in FIG. Reference numeral 23 denotes a taper angle. As in this embodiment, when the pin is tapered to further enhance the connection effect, the taper angle 23 is set as follows. That is, in general, the friction angle related to fitting in the absence of lubricant is considered to be 0.2 to 0.4, and the taper gradient α is tan α = 1/20 to 1 when considering semi-permanent mounting. / 40 is used. Here, the reason why the friction angle is assumed to be fit when there is no lubricant is that even if a lubricant can be used at the time of assembly, if a high-pressure first stage blade of 600 ° C. or higher is assumed, there is lubricating oil. This is because there is no temperature environment.

  Next, the material of the contact pin 6 will be described.

  The contact pin 6 according to the present invention is attached in anticipation of two effects of a coupling effect and a damping effect. As described above, as described above, there are an effect of increasing the contact connection by a relative difference in centrifugal force made of a material having a specific gravity different from that of the wing material, and an effect of increasing the contact connection by a taper. In addition to this, the effect of increasing the contact connection can be expected by using a material having a linear expansion coefficient (thermal expansion coefficient) different from that of the wing material by using exposure to a high temperature of 600 ° C. or higher.

  Regarding the difference in linear expansion coefficient, for example, even when the turbine blade is made of 12Cr steel or the like, the turbine blade and disk part are made of the same material such as 12Cr steel and have a linear expansion coefficient of less than 600 ° C. In this case, since the Ni-based alloy material has a higher linear expansion coefficient than 12Cr steel, if it is used as a pin material, the effect of increasing the contact force between the blades and the contact force between the blade grooves and the disk blade grooves can be obtained. I can expect. Further, when considering the use of a Ni-based alloy material for a turbine blade at a high temperature of 600 ° C. or higher, if the pin material is made of austenitic steel, the same effect as described above can be expected due to the difference in linear expansion coefficient. In addition, the contact pin is expected not only to increase the contact coupling force but also to increase the damping effect as a shock absorber. Therefore, when manufacturing the contact pin, it is desirable that the contact pin be manufactured by casting having excellent wear resistance and a high damping effect.

  Next, another embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the contact surfaces of the platform portion 3 and the cover portion 2 are configured to have an oblique angle 22 with respect to the axial line 21 of the turbine. Thus, by having an oblique angle 22 with respect to the axial line 21, not only the circumferential direction but also the excitation force due to the transient fluid force in the axial direction is caused by the sliding and frictional effects of the contact surface. Expected to work as a shock absorber. In addition, since the contact surfaces of the cover part 2 and the platform part 3 are arranged in parallel, the damping effect acting on the turbine blades is attenuated while acting in the same direction on the cover part 2 and the platform part 3, so that the twisting In addition, it is possible to suppress excessive torsional deformation of the moving blade profile portion 1 and reduce the possibility that the blade groove portion 4 and the cover portion 2 cause a single contact.

  The embodiments shown in FIGS. 5 and 7 can be combined, and a turbine blade having higher reliability can be obtained by this combination.

The block diagram of the turbine rotor blade which is an Example of this invention. The blade profile outline drawing of the turbine rotor blade which is an Example of this invention. 1 is a perspective view (schematic diagram) of a turbine rotor blade that is an embodiment of the present invention. FIG. BRIEF DESCRIPTION OF THE DRAWINGS The schematic of the steam inlet part of the high power type high pressure turbine which applied the turbine rotor blade which is the Example of this invention to the first stage paragraph. The block diagram of the turbine blade which is the other Example of this invention. The schematic diagram of the pin shape of the contact pin used for the turbine rotor blade which is another Example of this invention. The figure which looked at the turbine rotor blade which is the other Example of this invention from the outer periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor profile part 2 Cover part 3 Platform part 4 Blade groove part 5 Disk part 6 Contact pin 10 Turbine rotor

Claims (6)

A blade profile part, a cover part provided on the outer peripheral side of the blade profile part, a platform part provided on the inner peripheral side of the blade profile part, and two or more provided on the inner peripheral side of the platform part A turbine rotor blade structure including a plurality of turbine rotor blades having a plurality of blade groove portions, and being assembled by inserting the blade groove portions of the turbine rotor blades into blade grooves formed in a disk portion of a turbine rotor from a turbine axial direction. And
The turbine blade has a blade profile in which the blade profile portion is twisted from the blade root to the blade tip,
Adjacent turbine blades are contact-connected between adjacent blades on the circumferential surface of the platform portion and the circumferential surface of the cover portion so that the cover portion forms one ring when viewed from the outer periphery. A turbine rotor blade structure characterized by comprising: In claim 1,
The circumferential surface where the blade groove portion and the blade groove of the disk portion contact, the circumferential surface of the adjacent platform portion, and the circumferential surface of the cover portion have an angle inclined with respect to the turbine shaft direction. Characteristic turbine blade structure. In claim 1 or 2,
Pins are respectively inserted between the circumferential surface where the blade groove portion and the blade groove of the disk portion contact, and between the circumferential surface of the adjacent platform portion and the circumferential surface of the cover portion,
A turbine rotor blade structure characterized by being contact-connected by the pins. In claim 3,
The turbine blade structure according to claim 1, wherein the pins between the circumferential surfaces of the cover part and the pins between the circumferential surfaces of the blade groove parts are parallel to each other. In claim 3 or 4,
The pin inserted between the circumferential surfaces of the cover part,
A turbine rotor blade structure having a taper angle of tan α = 1/20 to 1/40. In any of claims 3 to 5,
The turbine blade structure according to claim 1, wherein a material of the pin inserted into the cover portion and the blade groove portion is a cast material having a higher linear expansion coefficient than the material of the turbine blade.

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