Patent Publication Number: US-6659716-B1

Title: Gas turbine having thermally insulating rings

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a gas turbine that can guarantee optimal clearance dimensions between rotor blades and a partition ring during operation. 
     2. Description of the Related Art 
     FIG. 2 shows an example of the schematic structure of a gas turbine plant. The gas turbine plant shown in this figure comprises a compressor  10 , a combustor  20 , and a gas turbine  30 . In this gas turbine plant, the compressed air that has been compressed by the compressor  10  is supplied to the combustor  20 , mixed with fuel supplied separately, and burned. The combusted gas generated by this combustion is supplied to the gas turbine  30 , and a rotational drive force is generated by the gas turbine. 
     Specifically, as shown in FIG. 3, inside the gas turbine  30 , a plurality of rotor blades  32  installed on the rotor  31  side and a plurality of stationary blades  33  installed on the stationary side on the periphery of the rotor  31  (not illustrated) are disposed alternating in the axial direction (the left to right direction in the figure) of the rotor  31 , and a combustion gas flow path  34  that passes therethrough is formed. Thereby, when the combustion gas supplied into the gas turbine  30  passes through the combustion gas flow path  34 , a rotational force is applied to the rotor  31  due to the rotation of each of the rotor blades  32 . This rotational force rotates the generators (not illustrated) connected to the rotor  31  to generate electricity. 
     However, in this gas turbine  30 , in order to introduce combustion gas into the interior, the components which have been heated to a high temperature must be cooled, and as shown in FIG. 2, a structure is generally used in which for example, a portion of the compressed air that has been compressed by the compressor  10  is incorporated into an a bleed and used to cool each of the rotor blades  32  and the stator blades  33 . 
     Among these multistage structures, the details of the bleed intake structure in the first stage will be explained below with reference to FIG.  4 . Moreover, this figure is an enlargement corresponding to part A in FIG. 3, where the left side of the page is the upstream flow direction of the combustion gas and the right side of the page is the downstream side. 
     On the outer periphery of each of the rotor blades  32 , a partition ring  35  having a ring shape is formed so as to conform to these rotor blades  32 , and the partition ring  35  is supported and anchored via the pair of thermally insulating rings  36   a  and  36   b . In order to avoid contact between each of the rotor blades  32  and the partition ring  35 , a predetermined clearance c is provided between the outer peripheral edge of each of the rotor blades  32  and the inner peripheral surface of the partition rings  35 . 
     The flow path  38   a  that opens towards the partition ring  35  is formed by the first stage rotor blades  32 , and the bleed f brought in from outside the gas turbine  30  is introduced. 
     Each of the thermally insulating rings  36   a  and  36   b  are a pair of ring shaped parts separated from each other, and in the outside peripheral part thereof, they are separately anchored within the first stage blade ring  38 . 
     In addition, a ring shaped impinging plate  39  and a partition ring  35  are installed and anchored is a state in which they are interposed between the thermally insulating rings  36   a  and  36   b . A plurality of through holes  39   a  are bored at substantially equal intervals with respect to the outer peripheral surface of a partition ring  35  for distributing and supplying the vapor oil f taken in via the flow path  38   a.    
     The flanges  35   a  and  35   b  are formed at the upstream side and the downstream side of the outer peripheral surface of the partition rings  35 , and these flanges  35   a  and  35   b  are engaged in a recess formed in each of the thermally insulating rings  36   a  and  36   b . Similarly, both ends of the impinging plate  39  engage in the recesses formed in each of the thermally insulating rings  36   a  and  36   b.    
     On the partition rings  35 , a plurality of cooling paths  35   c  that pass from the upstream side of the outer peripheral surface thereof through the interior to the downstream side end surface are formed. 
     The above explains the first stage structure among the plurality of stages, but the second and subsequent stages positioned on the downstream side therefrom also have substantially the same structure. 
     However, the clearance c changes due to the differences in thermal expansion between each of the structural components. When this becomes excessively large, there is the problem that the capacity of the gas turbine  30  drastically deteriorates. From this point of view, using an optimal clearance that takes into consideration the differences in thermal expansion between each of the structural components is necessary during the design stage. 
     However, actually the amount of thermal deformation of each component (for example, the blade rings of each stage starting with the first stage blade ring  38 ) differs at each of the stages, and thus optimal design is difficult. That is, because the flow conditions (temperature and the like) of the bleed f that cools each of the stages differs for each stage, there is the problem that it is difficult to design with a high precision the clearance c for each of the stages that conforms to the actual shape during operation. 
     Among these stages, the difference in thermal expansion between the first stage and the second stage is severe, and for example, when the temperature of the members of the second stage blade rings  38 A, which are the blade rings of the second stage, is approximately 360° C., at the first stage blade ring  38 , the temperature of the members is a comparatively high 450° C., and thus the clearance c of the first stage has a tendency to become larger than that of the second stage during operation. 
     The combustion gas flow path  34  has a shape in which the width dimension of the flow path gradually widens from the upstream side to the downstream side at each stage, and thus for the same clearance c, at the upstream first stage, whose flow path width is comparatively narrow, the amount of fluctuation of the clearance c with respect to the flow path width greatly influences the power of the gas turbine  30 . Against this background, a structure in which the clearance c is optimal during operation is desired. 
     In consideration of the above, it is an object of the present invention to provide a gas turbine that can minimize the clearance between each of the rotor blades and the partition rings during operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram showing one embodiment of the present invention and a enlarged diagram of the A section shown in FIG.  3 . 
     FIG. 2 is a diagram explaining schematic constitution of a gas turbine plant. 
     FIG. 3 is a diagram showing the combustion gas path of the gas turbine plant and a partial cross-sectional view of the section including the axial direction of the rotor. 
     FIG. 4 is a diagram showing the conventional gas turbine and this figure is an enlargement corresponding to part A in FIG.  3 . 
    
    
     SUMMARY OF THE INVENTION 
     The present invention uses the following device to solve the problems described above. 
     The first aspect of the present invention provide a gas turbine comprising, a plurality of rotor blades, which are disposed on the periphery of the rotor and rotate with the rotor, a plurality of partition rings which enclose the periphery of these rotor blades and forms a combustion gas flow path therein; and a plurality of blade rings which are disposed around the periphery of said partition rings and support said partition rings through a thermally insulating ring, wherein, when viewing from the axial direction of said rotor, the upstream thermally insulating ring, that supports the partition ring located relatively upstream among said plurality of partition rings, is installed on the downstream blade ring, which is positioned downstream of said blade ring, which corresponds to said upstream thermally insulating ring. 
     In the gas turbine according to the first aspect of the present invention, since the downstream blade rings that have a temperature lower than that of upstream blade rings positioned relatively on the upstream side has smaller amount of thermal expansion during operation, and thus, in comparison to the conventional installation of upstream thermally insulating rings on the blade rings of the upstream blade rings, the amount of the thermal expansion of the upstream thermally insulating rings can be limited to a small amount. 
     According to the second aspect of the present invention, the gas turbine according to the first aspect has a cantilever support structure in which an upstream thermally insulating ring is supported by a downstream blade ring when viewed in a cross-section along the axis of the rotor. 
     In the gas turbine according to the second aspect, the operation of the gas turbine described in the first aspect can be reliably obtained. 
     According to the third aspect of the present invention, in the gas turbine according to the first and second aspects, the upstream thermally insulating ring has a first member positioned relatively upstream in the direction of the flow of the combustion gas and a second member positioned on the downstream side with respect to the first member, and with respect to the downstream blade ring, the first member is installed in a state wherein the second member is interposed between the first member and the downstream blade ring. 
     In the gas turbine according to the third aspect, when maintaining the upstream thermally insulating rings in the gas turbine, it is possible to carry out simultaneously the removal of the second member and the separation of the first member from the second member by simply removing the first member from the downstream blade ring. 
     According to the fourth aspect of the present invention, in the gas turbine according to the third aspect, the other member is interposed between the first member and the second member. 
     In the gas turbine according to the fourth aspect, when maintaining the upstream thermally insulating rings of the gas turbine, it is possible to carry out simultaneously the removal of the second member and the separation of the first member from the second member by simply removing the first member from the downstream blade ring. Here, an impingement plate, for example, can be used as the aforementioned another member. 
     According to the fifth aspect of the present invention, in the gas turbine according to the fourth aspect, the other member can be integrally formed with either the first member or the second member. 
     The gas turbine according to the fifth aspect, the number of parts can be decreased, and thus the manufacturing cost can be reduced. In addition, the number of assembly steps can be reduced. 
     A sixth aspect of the present invention, in the gas turbine according to the third and fourth aspects, the fist member and the second member are integrally formed. 
     The gas turbine according to the sixth aspect, the number of parts can be reduced, and thus the manufacturing cost can be reduced. 
     A seventh aspect of the present invention, in the gas turbine according to any one of the first through sixth aspects, a clearance flow path, for flowing the cooling bleed towards said partition ring supported by said upstream thermally insulating ring, is formed between the upstream blade ring that covers the periphery of said upstream thermally insulating ring and said upstream thermally insulating ring. 
     The gas turbine according to the seventh aspect, formation of through holes for supplying bleed toward the partition ring supported by said upstream thermally insulating ring becomes unnecessary by forming the clearance flow path. 
     According to the eighth aspect of the present invention, in the gas turbine according to any one of the first through seventh aspects, the gas turbine further comprises a control unit that controls one or both of the temperature or the flow rate of the cooling bleed for cooling said partition ring, which is supported by said upstream thermally insulating ring. 
     In the gas turbine according to the eighth aspect, it becomes possible to actively control (active control) the dimension of the clearance formed between each of rotor blade and the partition ring in the unit stage having a partition ring supported by the upstream side thermally insulating ring. That is, by carrying out one of either lowering the bleed temperature or the bleed flow rate, the clearance can be narrowed. Contrariwise, by carrying out one of either raising the bleed temperature or lowering the bleed flow rate, the clearance can be widened. 
     According to the ninth aspect of the present invention, in the gas turbine according to the first aspect, the partition ring supported by said upstream thermally insulating ring is positioned in the first stage unit that is located furthest upstream in said axial direction of said rotor, and said downstream blade ring is positioned in the second stage unit located adjacent to said first stage unit. 
     In the gas turbine according to the ninth aspect, since the clearance between each of the rotor blades and the partition ring of the first stage unit located the furthest upstream has the greatest influence among the unit stages on the power loss of the gas turbine, the effect of the present invention can be effectively exhibited by controlling the clearance. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a drawing showing an embodiment of the gas turbine of the present invention, and is a partial enlarged drawing of the region corresponding to part A in FIG.  3 . 
     FIG. 2 is an explanatory drawing showing the schematic structure of the gas turbine plant. 
     FIG. 3 is a drawing showing the combustion gas flow path of a conventional gas turbine, and is a partial cross-sectional drawing viewed in a cross-section on the axis of the rotor. 
     FIG. 4 is a drawing showing a conventional gas turbine, and is an enlarged cross-sectional drawing of the part corresponding to part A in FIG.  3 . 
     DETAILED DESCRIPTION OF THE INVENTION 
     Below, an embodiment of the gas turbine of the present invention will be explained with reference to FIG.  1 . Of course, the present invention cannot be interpreted as being limited by the embodiment. Moreover, FIG. 1 is a drawing showing the essential components of the gas turbine of the present embodiment, and is a partial enlarged drawing corresponding to part A explained in the conventional technology. 
     The schematic structure of the gas turbine of the present invention comprises, in multiple stages in the axial direction of the rotor, unit stages comprising a plurality of rotor blades  32  that are disposed in a ring on the periphery of the rotor and rotate along with the rotor, a partition ring  35  that encloses the periphery of these rotor blades  32  and forms a combustion gas flow path  34  therein, and a blade ring (for example, the upstream blade ring  200  and the downstream blade ring  200 A to be described below) that covers the periphery of the thermally insulting ring (for example, the upstream thermally insulating ring  101 ) that supports the partition ring  35  therein, and is particularly characterized by the support structure of the partition ring  35 . 
     Below, mainly the characteristic features will be explained, but the other features that are identical to those in the structure explained in FIG. 3 have identical reference numerals, and their explanations are omitted. 
     As shown in FIG. 1, the gas turbine of the present embodiment has as one characteristic feature that, when viewing from the axial direction of the rotor, the upstream thermally insulating ring  101  is attached to the downstream blade ring  200 A, which is positioned downstream side of the upstream blade ring  200  corresponding to the upstream thermally insulating ring  101 . 
     In other words, in the direction of flow of the combustion gas that flows into the combustion gas flow path  34  (that is, the direction from the left side to the right side of the figure, and hereinafter, the left side of the figure is called as upstream and the right side is called as downstream), the first stage unit  100  is the unit stage positioned furthest upstream among the units, and the second stage unit  100 A is the unit adjacent to the first stage unit  100  on the downstream side. Moreover, the upstream blade ring  200 , which is the blade ring on the first stage unit  100  side, is positioned on the upstream side of the downstream blade ring  200 A. 
     The upstream thermally insulating ring  101  has a two-part structure wherein a first member  102  that is positioned on the upstream side is combined with a second member  103  that is positioned on the downstream side with respect to the first member  102 . 
     The first member  102  is a ring shaped member comprising an engagement groove  102   a  that engages the second member  103 , an engagement grove  102   b  that engages the impinging plate  39 , and an engagement groove  102   c  that engages the flange  35   a  of the partition ring  35 . Furthermore, a flange  102   d  for bolt anchoring on the downstream blade ring  200 A is formed on the first member  102 , and the through holes  102   d   1  through which the bolts  104  pass are disposed in a circle centered on the axis of the rotor. Similarly, a plurality of screw holes  200 A 1  are formed corresponding to each of the through holes  102   d   1  on the downstream blade ring  200 A. 
     The second member  103  is a round part that comprises an engagement groove  103   a  that engages with the impinging plate  39  and the engagement groove  103   b  that engages the flange  35   b  of the partition ring  35 . 
     In addition, the first member  102  is fastened by a plurality of bolts  104  in a state wherein the first member  102  is assembled by being interposed between the downstream blade ring  200 A, the second member  103 , the partition member  35  (the other member), and the impingement plate  39  (the other member). When viewed in cross-section on the axis of the rotor, the upstream thermally insulating ring  101  fastened in this manner has a cantilever support structure supported only by the downstream blade ring  200 A. 
     Moreover, in the present embodiment, the partition ring  35  and the impingement plate  39  have been respectively explained for the case that they are separate parts from the first member  102  and the second member  103 , but this is not limiting, and a structure wherein the respective partition rings  35  and the impingement plates  30  are formed integrally with the first member  102  and second member  103  can be used. In this case, the number of parts can be reduced, and thus the manufacturing cost can be reduced. In addition, the number of assembly steps can be reduced. 
     Similarly, in the present embodiment, the case was explained in which the first member  102  and the second member  103  are separate members, but this is not limiting, and a structure in which the first member  102  and the second member  103  are integrally formed can be used. In this case, the number of parts can be reduced, and thus the manufacturing cost can be reduced. 
     The clearance flow path  106  through which the cooling bleed f is supplied to the first stage unit  100  (the unit positioned on the upstream side) is formed between the inner peripheral surface of the upstream blade ring  200  that covers the periphery of the upstream thermally insulating ring  101  and the outer peripheral surface of the upstream thermally insulating ring  101 . The clearance flow path  106  is communicated with through holes  301 , which are formed in the supporting member  300  adjacent to the upstream side of the upstream thermally insulating ring  101  and th bleed f is introduced through this through holes  301 . 
     By forming the clearance flow path  106  in this manner, through holes for supplying the bleed f to the upstream blade ring  200  do not need to be formed. Therefore, deterioration in the structural strength of the upstream blade ring  200  can be prevented. 
     The gas turbine of the present embodiment provides a control apparatus  1000  that controls at least one of either the temperature or supply flow rate. This control apparatus comprises a cooling apparatus that adjusts the temperature of the bleed f and a flow rate control apparatus that adjusts the flow rate of the bleed f. Using this control apparatus, the clearance c formed between each of the rotor blades  32  and the partition ring  35  is actively controlled (active control) in the first stage unit  100 . Specifically, by carrying out one or both of lowering the bleed temperature or increasing the bleed flow rate, the clearance c can be narrowed. Contrariwise, by carrying out one or both of increasing the bleed temperature or decreasing the bleed flow rate, the clearance c can be widened. 
     According to the gas turbine of the embodiment explained above, by installing an upstream thermally insulating ring  101  on the downstream blade ring  200 A, the amount of thermal expansion of the upstream thermally insulating ring  101  (specifically, the amount of thermal expansion of the partition ring  35 ) can be made small during operation. Thereby, the clearance c between each of the rotor blades  32  and the partition ring  35  can be reduced to a minimum. 
     Moreover, in the gas turbine of the present embodiment, the present invention has a structure that is applied to the first unit  100  that is furthest upstream, but this is not limiting, and naturally this can be applied to the units that are downstream from the second stage unit  100 A. However, by applying the present invention to the first stage unit  100 , as is the case in this embodiment, the increase in power of the gas turbine can be particularly effectively attained. 
     According to a first aspect of the gas turbine of the present invention, by installing an upstream thermally insulating ring on the downstream blade ring, the amount of thermal expansion of the upstream thermally insulating ring can be made small during operation. Thereby, the clearance between each of the rotor the partition ring supported by the upstream thermally insulating ring can be reduced to a minimum. 
     In addition, according to a second aspect of the gas turbine, the effect of the first aspect can be reliably attained. 
     According to the third aspect of the gas turbine, a structure is used in which the upstream thermally insulating ring is partitioned into a first member and a second member, and the second member is installed interposed between the downstream blade ring and the first member. By using this type of partitioned structure, the upstream thermally insulating ring can be removed during maintenance, and mounting on the downstream blade ring becomes simplified, and the maintainability improves. 
     In addition, according to the fourth aspect of the gas turbine, by using a structure wherein the first member, the second member, and other members are interposed, a separate anchoring structure for anchoring the other members to the downstream blade ring becomes unnecessary, and since the number of parts can be reduced, the maintainability is improved. 
     In addition, according to a fifth aspect of the gas turbine, by integrally forming the other members with the first member and second member, the number of parts can be reduced, the manufacturing cost reduced, and the maintainability improved. 
     In addition, according to a sixth aspect of the gas turbine, by integrally forming the first member and second member, the number of parts can be decreased, and thus the manufacturing cost can be reduced. 
     In addition, according to the seventh aspect of the gas turbine, through holes for bleed supply do not need to be formed in the upstream blade ring side, and thus a decrease in the structural strength of the upstream blade ring can be avoided. 
     In addition, according to an eighth aspect of the gas turbine, by providing a control unit that controls either one or both of the temperature or supply flow rate of the bleed, the clearance formed between each of the rotor blades and the partition ring supported by the upstream thermally insulating ring can be actively controlled (active control) in the unit stage positioned on the upstream side. 
     In addition, according to a ninth aspect of the gas turbine, by applying the present invention to the first stage unit, the increase in power of the gas turbine can be particularly effectively obtained.