Coolant recirculation type gas turbine

Abstract: A high efficiency coolant collection type gas turbine is obtained by integrating a heat shielding header (175) between the moving blades (140) and the coolant supply flow path. Communication pipes (179) supply the coolant from the header to the individual blades. Header is also suitable to be integrated in the coolant collecting flow path (171).

Description: The present invention relates to a gas turbine having moving blades cooled with a coolant and, more particularly, to a coolant collection type gas turbine provided with flow paths for cooling moving blades inside the gas turbine rotor and made so as to collect the coolant after cooling the moving blades. Moving blades of a gas turbine, usually, are cooled with air supplied through an interior of a rotor in order to protect them from a high temperature combustion gas flowing in a combustion gas path (hereunder referred to as a gas path). Usually, a part of compressed air for combustion is used as a source of the air and discharged into the gas path after cooling. In gas turbines the higher the combustion gas temperature, the higher the efficiency. However, since a thermal load increases by making the combustion gas temperature higher, a flow rate of a cooling air is inherently increased. Discharging the cooling air into the gas path not only decreases the temperature of combustion gas, but disturbs a flow in the gas path and decreases the output performance of the turbine. Further, a coolant flowing in a circulating flow path in the rotor has revolution energy proportional to 2 powers of the radius, however, discharging the coolant from the moving blades arranged on the outer periphery of the rotor causes a lot of pumping power loss, and the loss increases proportionally to a flow rate of the coolant. Therefore, an effective efficiency improvement can not be expected by only making the temperature of combustion gas higher. In order to improve further the performance, it is necessary to collect the air supplied for cooling the moving blades to solve the above-mentioned problems. Therefore, for example, in a gas turbine disclosed in JP A 54-13809, a method of forming a course of supplying and collecting a coolant with piping inside the rotor is proposed, and in a gas turbine disclosed in JP A 3-275946 a method of forming a course of supply and collection of a coolant by perforating the inside of the rotor is proposed. Further, in the gas turbine disclosed in JP A 7-189739, an axial collection flow path is formed at a stacking connecting portion of a turbine rotor, and it is made so that the air after cooling blades is collected in the combustion chamber through the collection flow path. For constructing a coolant collection type gas turbine, it is necessary to form inside a turbine rotor a supply flow path for supplying a coolant for moving blades and a collection flow path for collecting the coolant after cooling. However, since cooling the moving blades increases the temperature of the coolant used therefor, thermal stresses occur in the rotor components having both the supply flow path and the collection flow path because of difference in coolant temperature. In the gas turbine of 1500°C class combustion gas temperature, since the temperature of a coolant rises to about 200-250°C in the case of air cooling and to about 150-200°C in the case of vapor cooling, excessively large thermal stresses beyond an allowable value may occur depending on construction of a flow path. Therefore, in order to realize a coolant collecting gas turbine of high efficiency by making the combustion gas temperature higher, it is one large subject to form a coolant supply flow path and a coolant collection flow path inside the rotor so as to reduce thermal stresses. In the closed cooling gas turbine disclosed in JP A 7-189739 or JP A 9-13902, a supply flow path and a collection flow path for cooling blades are present mixedly inside a rotor the collection flow path is provided with a heat insulated pipe, so that thermal stress occurs in construction components of the rotor because of the above-mentioned temperature elevation of coolant. Thermal stress is influenced by the structure of a rotor and a flow path, and the thermal stress also can be reduced by measures for thermal shielding. However, since the rotor is a rotary body rotating at a high speed, the structure thereof is limited much with respect to the strength. Although it is possible to form relatively easily a flow path at a stacking connecting portion, including the thermal shielding measures, the flow path construction has many problems such that branching and joining are necessary for forming communication flow paths between the flow path and blades at an outer periphery because many blades are connected, that stress is apt to increase upon perforation of the flow path because the disk has a thin thickness at the outer periphery side, further that large thermal stress occurs due to temperature difference between the side faces of the disc when counter flow is effected between coolant supply and coolant collection on the both side faces of the disc. Further, as a supply temperature of a coolant, about 250°C is effective in view of operation of the gas turbine system, and in this case, a collection temperature is 400-500°C. Thereby, the temperature of some portions goes beyond an allowable temperature of a turbine rotor material usually used, so that it is necessary to use a material of high heat resistance and high cost. An object of the present invention is to provide a coolant collection type gas turbine which is able to sufficiently reduce thermal stress of a rotor portion, caused by collecting a coolant for moving blades and to collect the coolant at a high efficiency. In order to achieve the above objects, a gas turbine according to the present invention is characterized in that a coolant supply flow path for supplying a coolant for cooling moving blades and a coolant collecting flow path for collecting the coolant after cooling the moving blades are provided inside the turbine rotor, a heat shielding header is provided between the moving blades and the coolant supply flow path or the coolant collecting flow path, the heat shielding header and the coolant supply flow path or the coolant collecting flow path are connected by at least one communication path, communication pipes are provided between the heat shielding header and the moving blades, and the coolant is supplied to and collected from the moving blades through the heat shielding header and the communication pipes. Further, the gas turbine is constructed so as to provide a ring-shaped projection concentric to the turbine rotor on an outer peripheral wall of the above-mentioned heat shielding header, and a ring-shaped concave engaging with the above-mentioned projection. Further, the above-mentioned heat shielding header is made so as to be able to be divided into a plurality of sections in a peripheral direction. Further, a pipe forming the above-mentioned communication path is made by a member different or separate from a main body of the heat shielding header, and the connecting portion between the main body of the heat shielding header and the pipe forming the communication path is made to be sliding fitting. Further, a gas turbine comprises a combustor producing combustion gas, a plurality of moving blades arranged in a flow path in which combustion gas flows, a disc supporting the moving blades, a distant piece one end of which is connected to the disc and the other end is connected to a compressor compressing combustion air, and a coolant collecting flow path, provided at those connecting portion, for collecting a coolant after cooling the moving blades, and the turbine is made so as to provide a spacer intervening between the distant piece and the disc, form, at the connecting portion between the spacer and the distant piece, a flow path extending radially and having a heat shielding member provided on the peripheral wall, and collect the coolant after the moving blades into the combustor through the flow path. Further, sealing devices are provided at each of an outer peripheral end of the distant piece and the spacer, a central hole is formed at a radially central portion of the distant piece, and a communication hole passing through between the sealing devices at the outer periphery portion from the central hole. That is, in the gas turbine formed thus, since the heat shielding header connected by the coolant collecting flow path and the communicating path and connected to the moving blades by the communication pipes of the same number as the number of the moving blades between the coolant collecting flow path (or coolant supply flow path) and the moving blades, and the coolant is collected from each of the moving blades through the heat shielding header and the communication pipes, thereby a lot of moving blades, that is, a moving blade group having a lot of coolant introduction outlets and the coolant paths inside the rotor can be smoothly connected, a quantity of heat conduction from the flow paths to the disc is decreased by the heat resistance of an air layer formed between the disc and the heat shielding header and the thermal stress is reduced greatly, and thermal stress at the rotor portion, caused by collecting the coolant for moving blades can be sufficiently reduced. Further, since the spacer is inserted between the distant piece and the disc, the flow path extending in a radial direction and provided with heat shielding member in the peripheral wall is formed in the joining portion between the spacer and the distant piece, and the coolant after cooling is collected into the combustor through the flow path, a part of the coolant supplied for the moving blades is led to the outer periphery of the distant piece, the distant piece and the rotor member around the distant piece are cooled, the rotor member can be kept at a low temperature, thermal stress caused in the rotor member by collecting the coolant for moving blades can be sufficiently reduced. Fig. 1 is a vertical sectional view of a coolant collection type gas turbine of an embodiment of the present invention; Fig. 2 is a view taken along a line X-X of Fig. 1; Fig. 3 is an enlarged view taken along a line Y-Y of Fig. 1; Fig. 4 is an appearance view of a header used for the coolant collection type gas turbine of the present embodiment; Fig. 5 is a view taken along a line W-W of Fig. 4; Fig. 6 is a vertical sectional view of an essential part of a coolant collection type gas turbine of another embodiment of the present invention; Fig. 7 is a partially sectional view taken along a line U-U of Fig. 6; Fig. 8 is a vertical sectional view of an essential part of a coolant collection type gas turbine of another embodiment of the present invention; and Fig. 9 is a sectional view taken along a line V-V of Fig. 8. An embodiment of the present invention is explained, referring to Fig. 1. Fig. 1 shows a section of an upper half of the coolant collection type gas turbine. The gas turbine shown in Fig. 1 is an example of an air cooling type gas turbine using air as a coolant. The gas turbine comprises a casing 110 covering the circumference thereof, a compressor 120 and a combustor 130 arranged inside the cover, a turbine 150 having nozzles 112, moving blades 140, a turbine rotor 160, etc., bearing 111 rotatably supporting the turbine rotor and an exhaust duct 113. A plurality of the moving blades 140 are arranged on the outer periphery of the turbine rotor 160 at predetermined circumferential intervals, and coolant flow paths 141 different in shape are formed inside each of the moving blades (first to third stages) so that the matrix material of the moving blades is able to bear a thermal load of the combustion gas flowing in the gas path 132. The turbine rotor 160 is constructed by fastening, with 4 bolts, 4 discs 161a to 161d, 3 spacers 162b to 162d and a shaft 163 at a stacking joining portion (hereunder referred to as a hub), and connected to the compressor 120 through a distant piece 151 and a spacer 162a. Central holes 164, 152, 122 are formed in the shaft 163 supported by the bearing portion, turbine rotor discs 161a to 161d having moving blades 140 planted thereon, the distant piece 151 and discs 121 at a high stage side of the compressor rotor, respectively. In the hub portion of the turbine rotor, a collecting flow path 171 extending axially from the spacer 162a to the spacer 162b is formed, and a heat shielding pipe 172 is inserted herein. Further, slits 173a to 173h each are formed to extend in the radial direction, and a heat shielding duct 174 is mounted in the slit 173a between the distant piece 151 and the spacer 162a. Further, heat shielding headers 175a, 175b are mounted in the slits 173c and 174d on the both sides of the spacer 162b. The others are only slits formed so that the rotor central hole 164 and cavities 166 at the radially outer side are communicated each other. Seals 114a to 114c are provided on the outer peripheries of both ends of the distant piece 151 and the spacer 162a. A space 115a between the seals 114a and 114b is communicated with the central hole 152 of the distant piece by a communication hole 116, and an outlet of the collecting flow path 171 is opened to a space 115b between the seals 114b and 114c. A slit 123 is formed in the hub joining portion of the compressor rotor. The central side of the slit communicates with a radially central hole 122 through a flow path between side walls of the disc 121 and the outer peripheral side is opened to a compression path through the cavity at the radially outer side of the hub. Fig. 2 is a view taken along a line X-X of Fig. 1. In Fig. 2, a plurality of the collecting flow paths 171 are arranged in an intermediate phase between bolt holes 199 arranged circumferentially. The collecting flow paths 171 and the slit 173b are arranged on the same phase, however, the collecting flow path is divided by the heat shielding pipe 172. The radially outside of the cavity 166a to which slits are opened communicate with coolant introducing ports 142 of all the moving blades. Fig. 3 is an enlarged view of a Y portion of Fig. 5, and Fig. 8 shows an appearance of a heat shielding header 175 viewed from a Z direction of Fig. 3. Fig. 5 is a sectional view taken along a line W-W of Fig. 4. As is noted from those Figures, the heat shielding header 175 is constructed of a plurality of circumferentially equally divided sectors, and each sector is constructed of a duct 176 at an inner diameter side, a chamber 178 at a central portion and pipe paths 179 at the radially outer side, the number of which pipe paths is the number obtained by dividing the number of moving blades at the outer diameter side by the number of division. A support ring 177 having an opening 177a is formed at the end portion of the duct 176, a recess 180 is formed at the side wall of the duct to minimize contact between the disc and the spacer. A flow path sectional area of the chamber 178 is sufficient to be about 1/2 the flow path sectional area of the duct 176. The number of pipe paths 179 is the number obtained by dividing the number of moving blades by the number of division. The side wall of each of the duct 176, chamber 178 and pipe path 179 is made thin for reducing the weight as long as the strength is secured. A hook 181 is formed on the outer wall of the chamber 178 over all circumferential region. That is, a ring-shaped projection (181) concentric to the turbine rotor is provided on the outside wall surface, a ring-shaped concave engaging with the projection, that is, a groove 182 is provided on the disc side and the hook 181 is engaged with the groove 182, as shown in Fig. 3. Further, the above-mentioned support ring 177 is formed so as to fit in the hole of the collecting flow path 171. By those engagement, a centrifugal load acting on the chamber 178 and the pipe paths 179 is supported mainly by the hook 181, and a centrifugal load of the duct 176 and the support ring itself is supported by the support ring 177. The positions in axial and peripheral directions are fixed by the slit 173 and any bolts are not used for the fixing. Upon assembling, the heat shielding header 175 is cooled and then cold-fitted in the disc. However, it is necessary to effect simultaneously fitting of the hook 181 and the groove 182 and filling of the support ring and the hole of the collecting flow path, so that an inner diameter side of the groove 181 not concerned with rotation support is formed a little smaller than the inner diameter side of the hook and the hook is able to be fitted even if the duct 176 shrunken during cooling. The pipe paths 179 of the heat shielding header are connected to coolant outlet ports 143 at the moving blade roots through communication holes 183 perforated in a rim at the outer periphery of the disc, and inside the communication holes 183 heat shielding pipes 184 are inserted. The heat shielding duct 174 provided at the joining portion of the distant piece 151 and the spacer 162a has a shape similar to that of the duct side of the above-mentioned heat shielding header 175. Referring to Fig. 3, a coolant (air) supplied from an end of the shaft 163 of the turbine rotor 160 by starting the gas turbine fills the central hole 165, and then it is divided into 7 courses as indicated by arrows 190a to 190g. The coolant supplied to the first and second stage moving blades through the courses 190a and 190b of the above-mentioned courses is greater part of the coolant supplied from the shaft end. The coolant having cooled the moving blades and flowed out from the coolant outlet ports 143 is joined in the chamber of the heat shielding header 175, and then collected into the combustion chamber 131 through the collecting flow path 171 and the slit 173. The coolant flows in the collecting flow path, which has elevated to a 200-250°C-higher temperature than that of a supply coolant by cooling or heat- exchanging with the moving blades. By mounting the heat shielding header, the heat shielding header itself rises to a temperature close to that of the collected coolant. However, since gaps, formed of the cavity 166 and the recesses 180 formed on the side walls of the duct, exist between the heat shielding header and the disc and the spacer, heat conduction from the collecting coolant to the disc and spacer around the heat shielding header is greatly limited by heat resistance of the gaps. Since the collecting flow path 171 and slit 173a have the heat shielding pipe 172 and heat shielding duct 174, substantially the same effect can be attained thereby. On the contrary, the inside of the rotor except for the coolant collecting courses is emerged in the supply coolant flowing in the courses 190a to 190c, so that the rotor material including portions around the coolant collecting courses is controlled strongly by heat conduction from the supply coolant and a uniform distribution of temperature close to the temperature of supply coolant is formed. Therefore, thermal stress generated in the rotor by collecting the coolant can be greatly reduced. Particularly, in the course that the temperature of the rotor is rising when the gas turbine starts, a thermal load partially acting on the rotor remarkably influences on the temperature distribution of the rotor, so that an effect is large even for reduction of unsteady thermal stress at the time of starting. There is some fear that thermal stress of the heat shielding header itself may increase by thermal expansion of the heat shielding header. The thermal stress is caused by thermal elongation of the chamber 178 in the peripheral direction and thermal elongation of the heat shielding duct 176, chamber 178 and pipe paths 179 in the radial direction. As for the thermal elongation of the chamber 178 in the peripheral direction of the above-mentioned thermal elongation, measures against that can be taken by providing gaps corresponding to the elongation at the boundaries between the divided sections. On the other hand, measures against the radial thermal elongation of the chamber 178 and pipe paths 179 can be taken by providing a gap 154a at the connecting portion between the tips of the pipe paths and the heat' shielding pipes 184 provided on the rim of the outer periphery of the disc. In this case, although it is considered that the collecting coolant may be flowed out from the gaps into the cavity 166, the flowing out never occurs because no discharge port for the collecting coolant flowed out. Flowing out of the coolant from the gaps can be prevented more surely by forming the gaps 154a in the communication holes and forming the pipe paths so that the tips of the pipe paths extend into the communication holes. This is effective even for supporting fluid force based on centrifugal force acting on the pipe paths 179 and a change in angular momentum of the coolant flowing in the radial direction. Further, it is greatly effective even for supporting inertia acting on the heat shielding header in the peripheral direction. Further, it is considered to more effectively reduce thermal stress by providing a communication hole 185 between the cavities 166a and 166b and introducing a small amout of supply coolant into the cavity 166b to positively form a low temperature atmosphere, however, the introduced coolant is better to be collected into the collecting course and in this case the gaps at the tips of the pipe paths can be effectively used as collecting ports for the collecting course. However, in the case where vapor is used as a coolant, although it is necessary to prevent the coolant from flowing out into the cavity and thereby prevent the vapor from condensing in the cavity, in this case, by providing elastic members such as seal rings and washer spring in the above-mentioned gaps, a sealing effect can be attained in addition to absorption of the elongation. On the other hand, the thermal elongation of the duct 176 is restricted by the hook 181 and the support ring 177, force in the same direction as the centrifugal force is applied on the hook and force in the opposite direction to the centrifugal force is applied on the support ring 177. Thereby, stress in the support ring is reduced while stress in the hook increases. However, the stress in the hook can be reduced by thinning the thickness of a d portion of the hook positioned at the duct connecting portion as shown in Fig. 4 or by deleting that portion and absorbing it by bending deformation of the chamber wall. Further, it is possible to form the duct and the chamber as separate pieces and assemble with a gap therebetween, that is, to assemble them to be sliding fitting so that thermal elongation can be absorbed by the gap. In this case, the recesses 180 and a collecting path inside the duct are communicated, however, since any flow is not formed in the recesses for the same reason as the case of the gaps at the tips of the pipe paths, it is unnecessary to seal the recesses. Next, when the coolant flows out from the outlet of the collecting flow path 171 into the outside of the rotor and flows into the combustion chamber 131, the coolant of high temperature leaked from the seal 114c flows in the gas path side through the wheel space 115c, and the outer periphery of the spacer 162a is heated. However, by leading out the coolant supplied inside the rotor from the communication hole 116 to the spacer 115a by the course 190g, the coolant flows toward the seal 114 a and the seal 114b, so that the outside wall of the distant piece can be sufficiently cooled by this coolant. That is, by mounting the seals 114a to 114c so as to cause the spacer 162a to intervene the seals, the portions the temperature of which becomes high can be limited to the spacer 162a. Hitherto, since the outer periphery of the distant piece is exposed to a coolant of high temperature flowing from a coolant collecting port to a compressor side, it was necessary to make it of a material of high heat resistance. However, by making the spacer of a separate member as mentioned above, it is possible to make the distant piece of a rotor material of excellent workability at a low cost. Further, the coolant flowing in the course 190f toward the compressor rotor side is for cooling the disc 121 of the compressor rotor, and the compressor rotor can be more effectively cooled by cooling the end flange of the distant piece connected to the end of the compressor rotor with the coolant leaked from the seal 114a. Another embodiment of the present invention different in construction of a heat shielding header is shown in Fig. 6 and Fig. 7. The heat shielding header 186 comprises a duct 187, a chamber 188 and pipe paths 189 each formed separately from each other. The duct 187 is supported by the support ring 177, the chamber 188 is supported by pins 155 inserted in hooks 153 at two positions and the pipe paths 189 is supported by the disc 161 through communication holes 183. By assembling those three kind of members into the rotor, a collecting course from coolant introduction ports of the moving blades to the collecting flow path 171 in the hub portion is formed. A flow path 156 inside the chamber 188 is formed so that a sectional area of the flow path increases toward a downstream side according to a flow rate of a joined flow. Thereby, the chamber is made light in weight and stress caused by centrifugal force is reduced. Further, by forming separately the three kinds of members as mentioned above, thermal expansion of them does not interfere with each other, and at the same time radial elongation of each is absorbed by gaps 154b, 154c, so that thermal stress can be reduced. Peripheral elongation of the chamber span between the hooks is restricted by the pins 155, so that compression stress occurs in the chamber in the peripheral direction. However, the span is about 1/2 of the peripheral length and elongation is small, so that stress is small. The pipe paths 189 are fitted in the communication holes 183 at the one ends by cold fitting, and since the other ends have gaps 154b between the holes of the chamber, the pipe paths are cantilevered for centrifugal force. Therefore, there is some fear that bending stress occurs in the pipe paths, the bending stress can be suppressed to an allowable range by making the gaps small, so that there is no problem in supporting structure. Since the above-mentioned coolant course has gaps at two positions, the collecting coolant flows out of the gap 154b at the upstream side and flows in the collecting course from the gap 154c at the downstream side. There is fear that coolant flows by-passing the cavities are formed. In this embodiment, flow paths 158 and 159 are formed in the hub at the inner side of the duct 187 and the side walls of the duct, respectively, and it is constructed so that a part of the supply coolant flowing in the central hole of the disc flows into the cavity 168 through the flow paths 158, 159 and the recesses 180 of the side walls. Since complicated coolant flow paths are formed inside the moving blade, a pressure loss is also large. Therefore, there is a large pressure difference between the supply coolant and the collecting coolant flowing the chamber. Since the coolant flowed in the cavity flows into the collecting course from the gaps 154b and 154c by the pressure difference, the above-mentioned flow by-passing the cavity can not be formed. Further, by the above-mentioned supply coolant flow, the side wall of the duct 187 is cooled and heat conduction from a flame 198 other than the recesses of the side wall to the disc is reduced, additionally, side surfaces around the cavity are also cooled. Therefore, a temperature distribution of the disc becomes more uniform and thermal stress caused by collecting the coolant can be reduced further. At the time of starting, since the disc is heated from both sides, there is an effect of reducing unsteady thermal stress at the starting. Further, in the above-mentioned course for a supply coolant, the coolant is introduced from the flow path 158, however, it is also possible to provide grooves in the rib of the heat shielding pipe 172 and the support ring 177 of the duct 187 and.supply the coolant from the supply slit 173b through the gap 193. In this case, also, an effect equivalent to the above-mentioned effect can be attained. A further another embodiment of the heat shielding header of the present invention is shown in Fig. 8 and Fig. 9. In this embodiment, as the section is shown in Fig. 13, an outer periphery side of a chamber 195 of the heat shielding header 194 is opened, and a structure that the header is joined with paths connected to the root portions of blades through a large gap is taken. Therefore, the constriction can be made simple, additionally, there is an advantage that centrifugal force of the chamber can be further reduced. The collecting coolant flows into inside the cavity 166 from the communication holes 183, and then it is collected through the heat shielding duct 187. However, since chamber inflow ports 196 are opened to the communication holes 183, and a pressure loss in the collecting course from the chamber to the combustion chamber is small, the coolant flowed out from the communication holes 183 flows so as to be absorbed into the chamber, the coolant blown off from the communication holes is not directly jetted to the wall surfaces of the disc 161 and the spacer 162. On the other hand, the supply coolant flowing in the recesses 180 of the heat shielding duct and flowed out into the cavity 166 from the outer periphery end joins the collecting coolant at the inflow ports 196 of the chamber and is collected inside the chamber, so that the cavities at the inner side than the inflow ports are filled with the supply coolant. Therefore, thermal stress occurs at the outer periphery side of the disc, however, since centrifugal stress caused in the outer periphery side is small, the resultant stress is small, and it is effective for a gas turbine in which a thermal load of the moving blade is relatively small. In the above-mentioned embodiment, the coolant for the moving blades of the third stage is not collected and discharged into the gas path side. However, in the case where coolant including the coolant for the third stage moving blades is collected, it is achieved by adding a heat shielding header between the spacer and the disc and extending the collecting flow path 171 so as to be connected to this header. Further, the flow path construction inside the rotor is changeable according to the scale of a gas turbine and a temperature level of combustion gas, however, as long as a heat shielding header is provided in the cavity at an outer side of a hub, even if it is provided in any cavity, the same effect can be attained. As one example thereof, it is considered that the supply course formed in the side face of the first stage disc 161a is exchanged with the collecting course, a space between the spacer 162a and the first stage disc is made as the collecting course, and a heat shielding flow path-formed header is inserted in this collecting course. Further, in order to damp an influence of the supply coolant, it is possible to provide the heat shielding header in the coolant supply course. Further, the flow path construction changes greatly according to kinds of coolant, and in the case of vapor cooling, it is effective to collect it in the shaft end. However, in this case, also, as long as a collecting course is formed in a hub portion, any problem does not occur, the same effect as above can be attained. Further, in the above embodiments, 4-stage turbines are taken as examples, as long as they are plural stages, the number of stages of the turbines is not limited. As variously explained above, with the coolant collection type gas turbine thus formed, as a construction of connection of the coolant flow paths and the moving blades, the communication hole is formed at the one end of the chamber, and the heat shielding header having the same number of communication pipes as the moving blades is inserted in the other end, whereby the moving blades having a lot of coolant inlets and outlets can be smoothly connected to coolant flow paths inside the rotor, a heat conduction amount from the flow paths to the disc is reduced by the heat resistance of air layer formed between the disc and the header, so that thermal stress can be greatly reduced. Further, in this case, which one of the supply course and the collecting course the above-mentioned heat shielding header is mounted on is decided according to a thermal stress occurrence condition, and in some cases it is possible to mount it on both of them. Further, a hook the section of which is ring-shaped is formed on the side wall of the above-mentioned header, and a recess is formed in the side wall of the disc opposite to the hook, whereby it is possible to support a strong centrifugal load at the time of rotation without fastening by bolts. Since the heat shielding header is divided circumferentially into a plurality of sections, slight gaps formed between the divided surfaces can allow circumferential elongation of the heat shielding header due to thermal expansion, and thermal stress acting on the heater itself can be reduced. Further, a construction of the rotors itself is also improved. That is, in a gas turbine in which a turbine rotor formed by laminating discs and a compressor are connected by a distant piece, and a coolant after cooling moving blades is collected into the combustion chamber, a collecting flow path radially extending is formed in the connecting portion of the distant piece and a spacer through the spacer between the distant piece and a first stage disc, and a heat shielding member is mounted in the collecting flow path, whereby a thermal load of the large sized distant piece due to collection of the coolant can be reduced and thermal stress can be greatly reduced. Seals are provided at both ends of the distant piece and the outer periphery of the spacer, while the distant piece has a central hole and communication hole passing through between the seals at the periphery from the central hole, so that a part of the coolant supplied for the moving blades is led to the outer periphery of the distant piece, the distant piece is sufficiently cooled by this coolant and it is possible to keep the temperature of its surrounding members to a low temperature. As explained above, according to the embodiments, it is possible to sufficiently reduce thermal stress in a rotor portion due to collection of a coolant for moving blades, and it is possible to obtain this kind of a coolant collection type gas turbine which is able to effect a high efficiency collection.

Claims: A gas turbine (150) provided with a coolant supply flow path for supplying a coolant for cooling moving blades (140) and a coolant collecting flow path (171) for collecting the coolant after cooling the moving blades (140) inside a turbine rotor (160) having discs (161, 161a, 161b, 161c) and spacers (162a, 162b, 162c, 162d), comprising at least one heat shielding header (175, 175a, 175b, 186, 194) mounted in the coolant supply flow path and/or in the collecting flow path (171) and located between the spacer (162a, 162b, 162c, 162d) and the disc (161, 161a, 161b, 161c), and between the moving biades (140) and an axially extending portion of the coolant supply flow path or an axially extending portion of the coolant collecting flow path (171), wherein at least one communication path is provided for connecting the heat shielding header (175, 175a, 175b, 186, 194) and the axially extending portion of the coolant supply flow path or the axially extending portion of the coolant collecting flow path (171), wherein communication pipes of the same number as the number of the moving blades are provided between the heat shielding header (175, 175a, 175b, 186, 194) and the moving blades (140), and wherein a coolant is supplied to or collected from the moving blades (140) through the heat shielding header (175, 175a, 175b, 186, 194) and the communication pipes. A gas turbine according claim 1, characterized in that on an outer side wall surface of the heat shielding header (175, 175a, 175b, 186, 194) is provided a ring-shaped projection (181) concentric to the turbine rotor (160), on the disc (161, 161a, 161b, 161c) side is provided a groove (182) and the ring-shaped projection (181) is engaged with the groove (182). A gas turbine according to claim 1 or 2, characterized in that the heat shielding header (175, 175a, 175b, 186, 194) is formed to be circumferentially separable into a plurality of sectors. A gas turbine according to any of the preceding claims, characterized in that a pipe forming the at least one communication path is formed in a separate member separated from a main body of the heat shielding header (186), and a connecting portion of the main body of the heat shielding header (186) and the pipe forming the communication path is formed to be sliding fit.

Inventors: IKEGUCHI TAKASHI, KAWAIKE KAZUHIKO, MARUSHIMA SHINYA, MATSUMOTO MANABU, IKEGUCHI, TAKASHI, KAWAIKE, KAZUHIKO, MARUSHIMA, SHINYA, MATSUMOTO, MANABU
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1998
Main classification: F01D5
IPC codes: F01D5, F01D25