Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
2002-05-02
2003-11-18
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
C416S09600A, C416S144000, C415S115000
Reexamination Certificate
active
06648600
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a turbine rotor formed by stacking disk shaped members in axial direction, and more particularly to a turbine rotor inserted heat resisting pipes by forming therein coolant flow passages in axial direction.
DESCRIPTION OF THE RELATED ART
In general, a gas turbine in a thermal power generation plant is constructed with a compressor sucking an air (atmospheric air) and compressing up to a predetermined pressure, a combustor mixing the air compressed by the compressor with a fuel and burning for generating a combustion gas, and a turbine portion generating a driving force by expansion of a high temperature and high pressure combustion gas. Also, a gas turbine power generation facility is constructed by providing a generator converting the driving force generated by the turbine into an electric energy.
Amongst, the turbine portion is constructed with a turbine casing mainly housing the entire construction, a combustion gas flow path acting and flowing the combustion gas generated by the combustor, vanes and blades alternately arranged within the combustion gas flow path, and a turbine rotor formed by stacking turbine disks and spacer disks. The vanes are fixed on the inner periphery of the turbine casing and the blades are fixed on the outer periphery of the turbine rotor, respectively.
In the construction of the turbine portion, by flow of the high temperature combustion gas through the combustion gas flow oat, the turbine rotor is driven to rotate at high speed to generate the driving force (shaft rotating force). Accordingly, for obtaining high output by the gas turbine, it is an important point for elevating temperature of the combustion gas and for enhancing efficiency of the gas turbine at the entrance of the turbine portion.
Associating elevated temperature and enhanced efficiency of the gas turbine, it is essential to cool high temperature portion of the gas turbine, such as turbine blades and the combustion has flow path, for certainly attaining reliability of the gas turbine facility. Accordingly, particularly in the turbine blades, a blade cooling system is employed for protecting blade members from heat of the high temperature combustion gas flowing through the combustion gas flow path.
In the blade cooling system, there are some systems which use air extracted at a predetermined pressure from the compressor or a steam extracted from a steam turbine in a combined cycle power plant, development of which has been progressed in the recent years, is used as coolant. Such coolant is fed to each turbine blade through a coolant supply passage provided within the turbine rotor to cool the blades by flowing through the blade cooling path formed within each blade.
On the other hand, in such blade cooling system, as one type depending upon handling method of the coolant after cooling the blade, there is an open cooling system by directly discharging the coolant into the combustion gas flow path through slits or conduits formed in the blades. Since the coolant is discharged into the combustion gas flow passage after cooling the blade, the open cooling system causes lowering of the combustion gas temperature, mixing loss of the coolant and the combustion gas and lowering of performance of the turbine to lower efficiency of the turbine.
Accordingly, in order to improve efficiency of the gas turbine, in order to improve efficiency of the gas turbine, there has been proposed a closed cooling system, in which the coolant after cooling the blades is not discharged into the combustion gas flow path but is connected in the combustion chamber of steam turbine via a coolant recovery path provided within the turbine rotor.
As the conventional construction of the blade cooling system in such closed cooling system, there is a system disclosed in Japanese Patent Application Laid-Open No. Heisei 10 (1998)-220201, for example, in which coolant supply paths for supplying the coolant to the blades and coolant recovery paths for collecting coolant after cooling the blades (hereinafter, both are generally referred to as coolant flow path) are formed through the inside of the turbine rotor in axial direction, namely, provided perpendicularly intersecting with each disk shaped member and the stacking plane as mating surfaces of the disk shaped members.
On the other hand, in Japanese Patent Application Laid-Open No. Heisei 10-220201, there has been disclosed a construction for inserting the heat resisting pipes within the inside of the coolant flow paths with dividing per each disk shaped members. By this, thermal influence to each disk shaped member by flow the coolant can be reduced.
However, the following problems are encountered in the prior art.
In the construction of the turbine rotor as set forth above, the turbine disks carrying the blades on the outer periphery and the spacer disks disposed between the turbine disks are stacked, and a stacking bolt extends through perpendicularly to stacking planes. Even the coolant flow paths to flow the coolant, they are formed perpendicularly to respective stacking planes and extend therethrough. Accordingly, in relation to certainty of coupling of the turbine rotor and to sealing ability of the coolant flow paths, it is ideal in design that turbine disks and the spacer disks are tightly fitted with each other on the stacking planes without gaps.
However, when both of the coolant supply paths and coolant recovery paths are admixingly present in the turbine disks and the spacer disks, a temperature of the coolant in the coolant supply paths is about 250 C whereby a temperature absorbing temperature of the blade members is elevated as high as 500 C to cause thermal stress in the component members of the turbine disks and the spacer disks to cause non-uniform thermal deformation. This causes gaps in the stacking planes between the disk shaped members to be a cause of leakage of the coolant to the stacking planes. Due to leakage to the stacking planes, predetermined flow rate of coolant to the turbine blades cannot be certainly supplied to cause degradation of reliability and durability of the blade members.
The heat resisting pipes disclosed in Japanese Patent Application Laid-Open No. Heisei 10-220201 are for reducing thermal stress to be caused in respective disk shaped members due to temperature difference between the supply paths and the collecting paths of the coolant as set forth above. By inserting the heat resisting pipe having smaller internal diameter into respective coolant flow paths for reducing thermal influence to the external disk shaped member from the inside of the pipes.
On the other than, on the stacking surface, due to precision in production, since positions of forming the coolant flow paths between respective disk shaped members can be offset in circumferential direction and radial direction, it becomes necessary to make the external diameter of the heat resisting pipes small when single long heat resisting pipe is inserted through respective coolant flow paths. However, in the coolant flow paths in each disk shaped member, the gap is formed between the external diameter of the heat resisting pipe and the internal diameter of the coolant flow path. This gap may cause extra stress on the heat resisting pipe during operation to lower durability of the heat resisting pipe. Therefore, a problem is encountered in inserting single long heat resisting pipe. Furthermore, since the heat resisting pipe transports the coolant for cooling the blade, it is abruptly heated in comparison with each disk member to cause displacement of the heat resisting pipe in axial direction due to thermal elongation. Then, by centrifugal force developed by rotation of the rotor, the heat resisting pipe and the inner periphery of the coolant flow path contact to cause wearing in the heat resisting pipe due to displacement in the axial direction of the heat resisting pipe on the contact surface. As set forth above, when one long heat resisting pipe is installed, displacement of the heat resisting pipe in axia
Higuchi Shin'ichi
Marushima Shinya
Takahashi Yasuo
Takano Tsuyoshi
Hitachi , Ltd.
Look Edward K.
Mattingly Stanger & Malur, P.C.
McAleenan J. M.
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