US 2487514 A
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Nov. 8, 1949 G. K. W BOESTAD ET AL TURBINE ROTOR COOLING Filed Dec. l, 1943 4 Sheets-Sheet l Nov. 8, 1949 G. K. w. BoEsTAD ET AL 2,487,514
TURBINE ROTOR COOLING 4 Sheets-Sheet 2 Filed Dec. l, 1943 5y IW `ATTORNEY G. K. W. BOESTAD ET vAl..
Nov. s, 1ga49 TURBINE ROTOR COOLING 4 sheds-sheet s Filed Dec. 1, 1943 Patented Nov. 8, 1949 2,481,514 TURBINE no'ron oooLTNG Gustav Karl William Boestad and hErik Otto Eriksson, Ldingo, Sweden, assignors, by mesno assignments, to Jarvis C. Marble, Leslie M. Me!- rill, and Percy H. Batten, as trustees Application December 1, 1943, Serial No. 512,474 In Sweden January 16, 1943 6 claims. (ci. en -41) This application is a continuation-in-part and as to common subject matter disclosed constitutes a division of our copending application Serial No. 509,800 filed November 10, 1943, (now Patent No. 2,462,600).
In turbines operating with high temperature motive fluid such for example as in gas turbines, it is desirable to cool the turbine bl des particularly the rotating blades, but it is diilicult and requires much energy to directly cool the rotating blades effectively, since their total surface area. is large and the coefficients of heat transfer between the gaseous motive fluid and the blade surfaces are very high.
1t is therefore a general object of the present invention to provide improved rotor cooling means, more particularly for turbines of the multi-stage type, which will have a high cooling eiect and which will require only a small consumption of energy. stantially by the fact that the interior of vthe rotor communicates through channels with the passage containing the blades, preferably with the space behind the first guide blade, so that the gaseous or vaporous cooling medium after having passed the rotor escapes to said passage. According to a further feature of the invention, the cooling agent has, immediately before entering the rotor, a pressure which is somewhat higher than the pressure of the driving medium in that portion of the passage wherein said channels open. In the application of the invention in gas turbine plants, the interior of the rotor communicates with a compressor or some other part of the gas turbine plant through conduits adapted to take off a portion of the working medium and to introduce the same into .the rotor.
For example, if 3% of the air quantity delivered by the compressor is used for the cooling of the rotor and such air is introduced behind the rst guide blade in a turbine comprising ten rotational blade rims, the loss in work for .the gas turbine plant will only be about 0.3%. A reduction of the temperature by` 100 C., permitting an increase of the temperature of the driving or working medium by a corresponding amount, results in an increase of the quantity of heat utilized in the turbine of the magnitude of By the fact that the cooling medium is subjected to pressure, the coelilcient of heat transfer between the same and the surfaces of the rotor will be high.
If the rotor is composed of disks carrying the various rotational blade rims, which are provided with mutual radial spaces, and which are connected with each other radially inside and outside these spaces, the latter may communicate with one another through openings in the disks, said openings being located alternately on different radii. The air will thus have imparted thereto, simultaneously with the axial movement, a rotary movement relatively to the rotor disks, whichA further increases the coecient of heat transfer between the cooling air and the walls of the rotor disks. It is important, moreover, that the outer por-tions of the rotor be cooled as effectively as that the path of heat conduction between the root of the blade and consequently the cooled rotor surface be short. By such construction .the blade root and the portion of the blade adjacent to the root and subjected to the highest stresses will also be effectively cooled.
If there are no radial spaces as stated vabove in the rotor, which is the case, for instance, where the rotor has an integral blade-carrying part, the cooling channels are arranged outside ,the average diameter of the rotor and preferably near the peripheral portion of the rotor, to ensure effective cooling of the blade attachments, besides which the whole rotor is kept at a low temperature inside the channels.
Further objects and advantages of the invention will be apparent from the following description considered in connection `with the accompanying drawings which form a part of this specication, and of which:
Fig. 1 is a horizontal view, partly in section, of a gas turbine constructed in accordance with the invention.
Fig. 2 shows the portion of the turbine framed by the lines'-Z-Z-Z in Fig. 1, on an enlarged scale.
Fig. 3 shows a gas turbine according to another embodiment and in the same projection as in Fig. 1.
Figs. 4 and 5 show two embodiments of gas turbine plants, partly in section, said plants being provided with a cooling device in accordance with the invention. Y
In the various ngures, corresponding parts have been designated by the same reference numerals.
In Fig. 1, I designates the rotor generally which is composed of a number of turbine disks I2, the inner diameter of which is spaced apart from the axis of rotation, so that an inner axial passage I 4 is produced. The disks I2 are preferably connected with each other through welding both at the inner and at the outer peripheral portions thereof, as indicated at I6, I8 (Fig. 2). The spaces 20 provided between the turbine disks and extending nearly out to the blade attachments will thus become sealed against the surrounding. The turbine disks I2 are provided with axial channels 22 which are disposed alternately on diierent radii and connect the various spaces 20 with eachother.
'I'he disks I2 of the rotor carry blades 24 which are arranged, together with guide blades 26 secured in the turbine housing 8, in a passage 3U having the gaseous working medium -owing therethrough. The outermost turbine disk I2 on the left hand side in Fig. 1 (the high pressure side of the turbine) may, over a preferably conical portion 32, be made integral with a shaft 34 cooperating in known manner with radial and axial thrust bearings 35 secured in the turbine housing. Arranged between the portion 32 and the shaft 34 are packing members 36, 38 on both sides of the bearing 35. The outermost disk I2 on the opposite side of the rotor is connected to a shaft 44 mounted in bearing 42. A small portion of the working medium of the gas turbine plant, such as the air which is compressed by a compressor contained in the gas turbine plant, may be conveyed through a socket 46 to an annular chamber 48 in the housing 28 and thence through channels 50 as well as through channels 5I -inthe iirst guide blade i'im 26 at the high Pressure end of the turbine to channels 52 opening into a chamber 54 at the left hand of the disk I2 in the drawings. From the chamber 54, the cooling air iiows through 'the channels 22 to the spaces 20 in the rotor, a relative rotary movement being set up between the cooling air and the Vwalls of the turbine disk, so that high coeiicients of heat transfer are obtained. The cooling air then` enters the channel I4, which is closed on both sides, and continues through a radial channel 56 in the rst turbine disk I2 at the high pressure end of the rotor, whereupon the cooling air is introduced into the space 58 behind the rst guide blade 26 and is carried along with the current of driving medium iowing through the passage 30. The space 58 is separated from the chamber 54 by means of packings 60.
The cooling air is taken off at such a point on or behind the compressor vthat when entering the interior of the rotor it will have a pressure omewhat higher than the pressure in the space The rotor I0 may be made from steel of the martensitic or some equivalent type. On the other hand, the blades 24 are made from itic or some equi alent steel having a high heat resistivity. The latter steel at the same time has acoeiiicient of heat expansion about 50% greater and a less heat conductivity than martensitic steels. Hereby, the rotor proper as Well reduced to a great extent. comparatively small portion in temperature are The blades occupy a greater heat of the blades is of little expansion on the part import. The turbine Furthermore, the housing against the hot working 28 may be protected medium by means of the points of attachment o1' the blades 24 as possible. The channels 62 are no through-pas sages at the right hand end of the rotor I 0 in the drawing, but communicate through radial channels 64 with the central channel I4. The cooling air is conveyed from the space 48 to the chamber 54 through passages 66, 68 in reinforcing members 'I0 located in front of the first guide blade and in the housing 28.
The gas turbine plant illustrated in Fig. 4 comprises a compressor 12 which is driven by the gas turbine 14, the blade-carrying rotor I D of which may form an integral part as in the embodiment according to Fig. 3. The air comthrough the channels 62, I4, 56 to the rear side of the rst guide blade rim 26 in the A conduit 90 extending from the conduit I6 may be connected with the a three-way valve 93 being inrotor in normal operation.
It is advantageous to form the turbine in such essieu manner that-the rotor may bel heated up` more in normal operation of the turbine. To obviate disadvantages of this kind, there I Y valve 92 in the conduit 16 behind the outtalefor the conduit 90, viewed in the direction of flowof the air. The valve 92 is closed more or less, whil the fuel supply g at the same time. All air from the compressor 96 now flows through conduits 90, 9| to the interior of the rotor. To this end the valve 93 may be operated automatically to open the passage between the said conduits when the valve 92 is closed. Through the kinetic energy of the rotating masses, the rotor is kept running for a while, and the rotation may be maintained for a longer time with the aid of the starting motor 94, if required. In this way, an efficient cooling of the rotor may be had also when the rotation is slow.
In the embodiment according to Fig. 5, 12 designates a low pressure compressor and 96 a high pressure compressor, the conduit between them having an air cooler 90 arranged therein. 14 denotes the low pressure turbine driving the compressor, and designates the high pressure turbine driving the compressor 96. The air compressed in the compressor 96 to its final pressure flows through the conduit 16, the heat exchanger 00 and the combustion chamber 84 to the gas turbine |00 and from the latter to a combustion chamber |02, into which the fuel is introduced through a nozzle -|045 to reheat the working meenters the turbine 14. The turbine 14 also drives a generator (not shown). for example. In both turbines, the rotor is provided with a system of cooling passages according to the invention.
Extending from the conduit 82 and preferably also from the conduit 16 are conduits |03 and |05, respectively, which by the three-way valve 93 are connected to a conduit |06. Cooling air is supplied through said conduits and a branch conduit |08 to the rotor of the high pressure turbine |00. The conduit |06 communicates with a conduit ||2 extending from the outlet |0| of the high pressure turbine to the cooling system of the low pressure turbine, as well as withV a conduit |01 opening into the chamber 54 of the low pressure turbine. The conduit |01 may have a cooler ||0 connected into the same. Provided between the conduits |06, |01 and H2 is a three-way valve |I4 adapted to cut oir the conduit |06 .in normal operation, when cooling medium passes through the conduits ||2, |01 and through the cooler I|0 to the low pressure turbine. When the gas turbine plant is put out of operation, the valve H4 is shifted simultaneously with the closing of the valve 92, so that cooling air will now pass through the conduits |06 and |01 to the low pressure turbine. The valve 93 then also takes a. position to allow a flow of air through the conduits and |06. By this means, powerful cooling of both rotors will be obtained.
If desired, small holes or gaps may be provided in the outerbond of the disks I2 in the embodiment according to Figs. 1 and 2, said holes or gaps opening into the passage for the driving medium, to which passage a portion of the cooling air will thus escape directly.
Gas turbine system structure herein disclosed slowly, vwhereby Y sional applicatie and the sealing edges btween the latter may be worn to greater plays 'A is' provided ef 'l0 1 e l through the nozzle 86 is out off p tionary structures forms' the claimed subject se, and 'while several embodiments it is to be underof the latter havebeenvshown,
- [steed that theyareiiuustreuveoniy and that the Y scope of the invention includes all forms' of structure' falling'J-within "the 'purview of' the appended Y what we claimvis: 1j i. 1'. In an elastic iuitiA turbine,
carrying rotating andstationary biadesfirespectively and providing 'between them a channel having 'a blade'y system therein for expansion of motive 'fluid, the'interior. of said rotor being provided with'passages for conducting a fluid cooling'medium therethrough to cool lthe blade carrying structure ofthe rotor, inlet means for introducing a cooling medium under pressure to said passages and outlet means for discharging the cooling medium from said passages to said channel, said outlet means communicating with a zone in said channel on the discharge side of at least the first row of blades in said blade system, and sealing 4means between said rotor and stationary structures located to close communication between the inlet side of said first row of blades and the place of communication of said outlet means with said channel.
2. A structure as set forth in claim 1 in which said cooling passages are arranged so that the cooling medium iows from said inlet means generally lengthwise of the rotor adjacent to the periphery of the blade carrying portion of the rotor structure.
3. A structureas serl forth in claim 1 in which said cooling passages are arranged so that the cooling fluid flows from the inlet thereto generally lengthwise of the rotor adjacent to the outer periphery of the blade carrying portion of the rotor structure and thereafter ows generally lengthwise of the rotor through the central portion thereof.
4. A structure as set forth in claim l having said inlet means at the high pressure end of the rotor, said cooling passages comprising passages in the radially outer part of the blade carrying structure of the rotor communicating with said inlet means for flow of the cooling medium generally lengthwise of the rotor in the outer part thereof and a centrally located passage communicating with the passages in said radially outer part for return flow of cooling medium from the outlet toward the inlet end of the rotor, and said outlet means comprising passages for discharging the cooling medium from said central passage to the motive fluid channel adjacent to the inlet end of the rotor.
5. A structure as set forth in claim-1 having a hollow integral rotor structure, said cooling passages comprising a plurality of passages extending lengthwise through said structure and communicating at the high pressure end of the rotor with said inlet means and a central cooling passage communicating adjacent to the outlet end of the rotor'with said lengthwise extending passages and Said outlet means comprising between said central passage and the channel for motive fluid.
6. A structure as set forth in claim 1 in which the blade carrying portion ofthe rotor comprises a plurality of discs connnected together adjacent to their outer peripheries and also at places mattter of our divi- Y Serial No.1'18,262 filed Febru- Aary 25, 1949, the claimed subject matter -in the @present application lbeing restricted' to turbine structure per .rotor sta.-
spaced inwardly thereof, whereby to provide s, se-
ries of annular spaces between the discs, and openings in said discs for connecting said spaces to provide therewith the cooling passages aforesaid, said openings being so located relative to 5 each other in adjacent discs as to prevent straight axial ow through the rotor of the cooling medium and said spaces being connected for direct ow thereto of the cooling medium from said inlet means. f
GUSTAV KARL WILLIAM BOESTAD. ERIK OTTO ERIKSSON.
REFERENCES CITED The following references are of record in the 15 file of this patent:
` 8 UNITED STATES PA'I'ENrs Number Number