Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
2001-02-12
2002-10-15
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S805000, C415S178000
Reexamination Certificate
active
06463729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine and a combined cycle plant comprising combined cycles of this gas turbine and a steam turbine.
2. Description of the Prior Art
As one conventional example of the mentioned art, that disclosed by the Japanese laid-open patent application Hei 9(1997)-4411 is known. A conventional gas turbine mentioned therein is what is called a double casing type gas turbine comprising an outer casing (outer structural shell as a container) and a blade ring (inner shell) constituting an inner casing. In this gas turbine, the blade ring is provided surrounding first stage and second stage portions and is fitted with a ring segment (shroud) surrounding each of turbine rotor blades constituting a cascade of first stage rotor blades and another ring segment (shroud) surrounding each of turbine rotor blades constituting a cascade of second stage rotor blades. Likewise, the blade ring is fitted with an outer shroud of each of turbine stator blades constituting a cascade of first stage stator blades and another outer shroud of each of turbine stator blades constituting a cascade of second stage stator blades.
Also, the blade ring is supported to the outer casing via a plurality of pins extending in a radial direction of a turbine shaft so as to be expandable and contractible in the radial direction of the turbine shaft. In the blade ring, there are provided two flow passages (plenums) so as to extend along the first stage and second stage rotor blade cascades, so that heating medium supplied from a heating medium supply source which is irrespective of the gas turbine operation is flown therethrough. Accordingly, in this gas turbine, heating medium of an appropriate temperature is supplied to the respective flow passages of the blade ring so that the respective blade rings (as well as the ring segments) may be expanded and contracted in the radial direction of the turbine shaft. As the result of this, even if the turbine rotor blade is thermally expanded or contracted in the radial direction due to temperature changes of the working fluid in operation, a gap between a blade tip of the turbine rotor blade and the ring segment can be adjusted appropriately and a loss at the rotor blade tip can be reduced.
However, if temperature of the working fluid changes in operation of the gas turbine, there occurs a thermal expansion and contraction also in an extending direction of the turbine shaft (axial direction) in the ring segment which is located around the turbine rotor blades for forming an annular flow passage and in the outer shroud of the turbine stator blade. For this reason, while the ring segment and the outer shroud of the turbine stator blade, which are adjacent to each other, are arranged to abut on, or engage with, each other so as to be expandable and contractible in the axial direction, respectively, a gap between these members is enlarged according to the degree of the thermal expansion or contraction of each of the members so that the working fluid may leak out therethrough to invite an increase of the loss.
SUMMARY OF THE INVENTION
In view of the problem in the prior art, therefore, it is an object of the present invention to provide a gas turbine which is able to reduce a loss at a rotor blade tip and to reduce a loss caused by leakage of working fluid through a gap between members constituting an annular flow passage as well as to provide a combined cycle plant comprising such gas turbine.
A gas turbine, as claimed in Claim
1
of the present invention, for generating power by expanding a high temperature high pressure working fluid at a plurality of stages of a turbine stator blade a cascade provided in a turbine casing and a plurality of stages of a turbine rotor blade cascade fitted to a turbine shaft, is characterized in comprising; a first blade ring, supported to the turbine casing so as to be expandable and contractible in a radial direction of the turbine shaft, corresponding to a first turbine stator blade cascade and a first turbine rotor blade cascade which constitute any one stage of the plurality of stages; a second blade ring, supported to the turbine casing so as to be expandable and contractible in the radial direction of the turbine shaft, corresponding to a second turbine stator blade cascade and a second turbine rotor blade cascade which constitute another stage adjacent to the one stage; a first heating medium flow passage, provided in the first blade ring, for circulating therethrough a predetermined heating medium; a second heating medium flow passage, provided in the second blade ring, for circulating therethrough the predetermined heating medium; and a communication member for connecting the first blade ring and the second blade ring to each other and for communicating the first heating medium flow passage and the second heating medium flow passage with each other.
In the turbine included in the above gas turbine, the first blade ring which corresponds to any one stage (the first stage, for example) and the second blade ring which corresponds to another stage adjacent to the mentioned one stage (the second stage, for example) are provided and members constituting the annular flow passage (outer shrouds of the stator blades, ring segments, etc.) are supported by these first and second blade rings. Also, the first blade ring has the first heating medium flow passage formed preferably so as to surround the outer circumferential periphery of the first rotor blade cascade and the second blade ring has the second heating medium flow passage formed preferably so as to surround the outer circumferential periphery of the second rotor blade cascade, and a heating medium, such as steam supplied from a predetermined heating medium supply source, is circulated through the first and second heating medium flow passages. Thereby, in operation of the gas turbine, even if the turbine rotor blade expands or contracts in the radial direction of the turbine shaft due to temperature changes of the working fluid, the first and second blade rings are expanded or contracted in the radial direction and the gap between the blade tip of the turbine rotor blade and the members constituting the annular flow passage can be adjusted appropriately.
In this gas turbine, in addition to the above, the first blade ring and the second blade ring are connected to each other by the communication member so that both of the blade rings are integrated substantially. Moreover, the first heating medium flow passage and the second heating medium flow passage are communicated with each other via a flow passage provided in the communication member. Accordingly, the heating medium supplied into the first heating medium flow passage, etc. is to flow through the flow passage of the communication member which connects the first blade ring and the second blade ring to each other and hence, like the first blade ring and the second blade ring, the communication member also expands and contracts corresponding to the temperature of the heating medium.
As the result of this, in the present gas turbine, the heating medium of an appropriate temperature is supplied into the first heating medium flow passage, etc. and thereby the communication member connecting the first blade ring and the second blade ring to each other is expanded or contracted and the position of the first blade ring and the second blade ring can be changed so as to correspond to and follow the constituting members of the annular flow passage which is expanded or contracted by the temperature changes of the working fluid, etc. By so doing, in the present gas turbine, the blade tip loss of the rotor blade can be reduced and the loss caused by leakage of the working fluid through the gap between the members constituting the annular flow passage can be reduced.
In this case, the mentioned gas turbine preferably further comprises a first annular member surrounding the first turbine rotor blade cascade and a second annular member surrounding the second turbine r
Hagi Naoki
Ichiryu Taku
Magoshi Ryotaro
Casaregola Louis J.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Combined cycle plant with gas turbine rotor clearance control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combined cycle plant with gas turbine rotor clearance control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combined cycle plant with gas turbine rotor clearance control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2989700