US3796044A

US3796044A - Gas turbine air storage system

Info

Publication number: US3796044A
Application number: US00241300A
Authority: US
Inventors: T Schwarz
Original assignee: Kraftwerk Union AG
Current assignee: Kraftwerk Union AG
Priority date: 1971-04-06
Filing date: 1972-04-05
Publication date: 1974-03-12
Anticipated expiration: 1991-03-12
Also published as: GB1337923A; FR2132456B1; NL7203983A; DE2116850A1; FR2132456A1

Abstract

Gas turbine air storage system with subterranean air storage space, for example, in a cavern formed in a salt stratum to which a bore hole extends, includes a plurality of tubes including an outer protective tube extending through the bore hole into the air storage space, a lining for the bore hole spaced from and surrounding the outer protective tube, the lining and the outer protective tube defining therebetween an annular space communicating with the air storage space, and means for feeding air to the air storage space at least partly through the annular space.

Description

United States Patent Schwarz Mar. 12, 1974 [54] GAS TURBINE AIR STORAGE SYSTEM 2,928, 11 I 3/1960 Johnson 137/236 2,787,455 4/1957 Knappen... 61/.5 X [75] Inventor Theodor Erlangen, 3,108,438 10/1963 Harvey 137/236 x Germany 3,538,340 ll/l970 Lang 290/52 [73] Assignec: Kraftwerk Union Aktlengesellschait,

Mulheim (Rhur), Germany Primary Examiner-Clarcncc R. Gordon Filed p 5 1972 Attorney, Agent, or FirmHerbert L. Lerner Appl. No.: 241,300

[30] Foreign Application Priority Data Apr. 6, 1971 Germany P 21 I6 850.3

m (is. er". 5159.29, 61/.5, 137/236, 290/52 [51] Int. Cl. F02c 9/14 [58] Field of Search 60/3929, 39.23; 137/236;

[56] References Cited UNITED STATES PATENTS 3,355,893 l2/l967 Kuhne 61/5 Gas turbine air storage system with subterranean air storage space, for example, in a cavern formed in a salt stratum to which a bore hole extends, includes a plurality of tubes including an outer protective tube extending through the bore hole into the air storage space, a lining for the bore hole spaced from and surrounding the outer protective tube, the lining and the outer protective tube defining therebetween an annular space communicating with the air storage space, and means for feeding air to the air storage space at least partly through the annular space.

ABSTRACT I 10 Claims, 3 Drawing Figures PAIENTEDHAR 12 I974 5 Flg 1 2 PRIOR ART GAS TURBINE AIR STORAGE SYSTEM The invention relates to a gas turbine air storage sys-- tem with a subterranean air storage space or reservoir, particularly in a salt cavern formed in a salt stratum. In the installation for such a system, a bore hole extends to the air storage space and is provided with a casing provided with several springs. An annular space is defined between the casing and the surrounding rock through which the hole is bored, and is usually filled with cement, it being important that an absolutely airtight seal be provided. The air riser tube can then be suspended within'the bore hole lining, and serves as a protective tube for the lining when the cavern is flushed.

For stored gaseous media, the annular space between the bore hole lining and the riser tube string is closed off by a so-called packer in the lower part of the bore hole, and the annular space thereabove is filled with a protective liquid. In this manner, adequate protection against corrosion of the casing is attained in that region of the bore hole.

In air storage spaces or reservoirs, the protective liquid can assume, in addition to protection against corrosion, the additional function of thermal insulation against temperature variations of the stored air, as long as the packer does not provide a thermal bridge of any significance. If the stored air is withdrawn relatively rapidly for operation of the gas turbine, the state of the stored air changes adiabetically, i.e., a temperature decrease takes place simultaneously with a reduction in pressure. When compressor air is fed into the storage I space, the change of state of the enclosed residual air quantity takes place in reverse, but generally more slowly. Because of the difference in thermal expansion and thermal conduction between the bore hole casing and the surrounding rock as well as the mass of concrete, the operational temperature variations in the bore hole lining must stay within given limits that are relatively narrow because, otherwise, development of leaks must be anticipated.

The application of ring-shaped sealing elements, i.e., the so-called packer with an outside diameter of half of a meter, for example, in shafts having a length of 500 m and more, required a large commercial and technical expenditure. Furthermore, in the case of great pressure differences, a tight seal for the protective liquid contained in the annular space located above the packer must be assured. The sealing effect of a packer installed in this manner can become questionable when the air pressure varies, especially when there is a temporary total withdrawal of the air.

The disadvantage must, however, always be taken into consideration that the tube sections located below the packer have no protection against corrosion since they are subject to condensation of humidity or air moisture which occurs when the pressure drops due to the withdrawal of air. This condensation, in conjunction with the deposition of salt particles from the caverns, forcibly result in intensive corrosion of the exposed tube sections.

It is accordingly an object of the invention to provide a gas turbine air storage system which avoids the foregoing disadvantages of the heretofore known systems of this general type.

With the foregoing and other objects in view, there is provided, in accordance with the invention, gas turbine air storage system with subterranean air storage space, for example, in a cavern formed in a salt stratum to which a bore hole extends, comprising a plurality of tubes including an outer protective tube extending through the bore hole into the air storage space, a lining for the bore hole spaced from and surrounding the outer protective tube, the lining and the outer protective tube defining therebetween an annular space communicating with the air storage space and means for feeding air to the air storage space at least partly through the annular space.

By means of this invention, it is possible to dispense with the packer or similar sealing elements entirely, since the supply of air into the storage space or reservoir takes place at least partly in the annular space defined by the protective tube and the bore hole lining.

In accordance with another feature of the invention, air feeding means are provided for feeding, for example, a partial flow of the combustion air as fresh air into the annular space even during useful output operation of the gas turbine, so that corrosion protection of the entire length of tube is assured. If, therefore, a partial stream of compressed fresh air is fed from above into the annular space even when air is being withdrawn from the air storage space for turbine operation, and thereby a downward flow of air is continuously maintained in the entire annular space, no condensation of air moisture can take place therein, so that no corrosion can therefor occur.

As the accompanying air flows down into the storage space or reservoir, a considerable part of the heat is absorbed by this air and is transferred from the rising combustion air to the riser tube. The riser tube has additionally been provided on the inner surface thereof with a suitable protective layer for protection against corrosion such as a plastic lining, for example, the lining being simultaneously effective as thermal insulation.

When the operation is exclusively in the compressor mode, all or part of the fresh air supply flows through the annular space into the storage space or reservoir, so that during the densification of the enclosed air, an upwardly directed flow in the annular space is reliably prevented. Air moisture or humidity and salt particles from the storage space or reservoir can therefore not penetrate into the annular space and cannot precipitate or condense at the tube walls.

The temperature of the fresh air can be controlled in order to conform to the temperature of the surrounding rock in which the bore hole is formed. By admixing with the air, a medium to protect against corrosion prior to extended idle periods of the gas turbine, the possibility is afforded of protecting the walls of the annular space against rusting.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in gas turbine air storage system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments, when read in connection with the accompanying drawings, in which:

FIG. I is a diagrammatic sectional view of a gas turbine air storage system known in the prior art;

FIG. 2 is a view corresponding to that of FIG. 1 of an embodiment of the invention of the instant application; and

FIG. 3 is an enlarged diagrammatic view of the upper part of FIG. 2 showing a modification thereof.

Similar parts in each of the figures are identified by the same reference numerals.

Referring now to the drawing, and first particularly to FIG. 1 thereof, there is shown in the prior art system a subterranean storage space or reservoir 1 in the form of a cavern or cavity present in a salt stratum in the earth, the cavern being connected by a bore hole 2 to the ground surface 3. The bore hole 2 is provided with an inner lining 4, and a cement filling is provided in the annular space between and defined by the bore hole lining 4 and the rock surrounding 5 in which the bore hole 2 is formed. A protective tube 6 extends through the bore hole 2 into the air space cavern 1 and is used as an air riser tube during the operation of the gas turbine air storage system. As shown in the prior art representation of FIG. 1, a ring-shaped seal in the form of a packing or a so-called packer 7 has been provided heretofore with a protective liquid 8 located thereabove.

As FIG. 2 shows, in contrast to the prior art system of FIG. 1, the packer has been dispensed with because the entire quantity of air, or part thereof, is now passed into the hollow space or reservoir 1 through an annular space 9 located between the protective tube 6 and the bore hole lining 4. Air enters into the annular space 9 in direction of the arrow 10 through a line 11 in which a stopcock or shut-off valve 12 is provided, and flows downwardly in direction of the arrow 13. The stored air discharges in direction of the arrow 14 through the interior of the protective tube 6 i.e. in the annular space 15 therewithin. The tube 6, which is used as the air riser tube, is provided with a protective heat insulating layer on the inner surface thereof, which has the effect of protecting the tube 6 against corrosion. The stored air is conducted in direction of the arrow 18 to the gas turbine installation proper (not shown) through a line 16 provided with a shut-off valve 17. A

tube

19, 20 serves for elutriation or washing out the air reservoir 1, the salt water and residual water being drawn off therethrough in direction of the arrow 21.

Whereas, in the embodiment of FIG. 2, the

tubes

6 and 16 serving for discharge of the stored air are traversed by the air flow only in upward direction, it is also possible to use these

tubes

6 and 16 for feeding-in the air to be stored or to have them participate in this process, and thus to operate with a downward flow therethrough. An example of an embodiment operating in this manner is shown in FIG. 3. As air is withdrawn through the protective tube 6 serving as the air withdrawal tube, the air flows in direction of the arrow 18 through the line 16 provided with shut-off

valves

17a and 17b, and subsequently travels through the line 23 to the non-illustrated gas turbine installation proper in direction of the arrow 24.

When storage air is supplied to the reservoir 1, it flows through the same pipe 23, but now in direction of the arrow 25, the main flow traveling with the

shutoff valves

17a and 17b in open condition, in direction of the arrow 26 through the line 16 and the protective tube 6. A partial flow of the compressed air which is to be fed into the storage reservoir 1 passes through a check valve member 27 and the shut-off valve 12, to the line 1 1, there the flow travels downwardly in the annular space 9 in direction of the arrow 10 to the storage reservoir 1.

The shut-ofi member 12 can, of course, be constructed as a control valve, in order to meter desirably the partial quantity of air flowing through it. The check valve 27 prevents, .when air is being withdrawn, a flow from rising in the annular space 9, which would mean danger of corrosion damage to the protective tube 6. The air riser tube is therefore always protected against corrosion, because it carries a protective layer on inner surface thereof and is protected from a rising air flow at the outer surface thereof in the manner hereinbefore described. It thus is possible, if desired, to force air in small quantities into the annular space 9, as indicated by the arrow 28 through an open shut-off valve 29, also when air is being withdrawn from the storage space 1, in order to reliably prevent, in conjunction with the check valve 27, an upward flow in the annular space 9.

I claim:

1. Gas turbine air storage system with subterranean air storage space, for example, in a cavern formed in a salt stratum to which a bore hole extends, comprising a plurality of tubes including an outer protective tube extending through the bore hole into the air storage space, a lining for the bore hole spaced from and surrounding said outer protective tube, said lining and said outer protective tube defining therebetween an annular space therebetween communicating with the air storage space, means for withdrawing air from said air storage space through said protective tube, and means for feeding at least a partial flow of the air to said air storage space through said annular space as said air is fed to the air storage space, thereby providing a downward flow of air in said annular space to preclude corrosion in said annular space.

2. System according to claim 1 wherein said means for withdrawing air from said storage space includes a tube located within said outer protective tube in the bore hole and extending out of said protective tube above ground and communicating with a gas turbine for supplying combustion air thereto from said subterranean air storage space during useful output operation of the gas turbine, said air feeding means being operable during the useful output operation of the gas turbine for feeding a partial flow of fresh air through said annular space between said bore hole lining and said protective tube to said subterranean storage space.

3. System according to claim 1 including a heatinsulating, corrosion-resistant lining disposed on the inner surface of said protective tube.

4. System according to claim 1 wherein said inner lining of said protective tube consists of synthetic resin.

5. System according to claim 1 including control means for maintaining the temperature of the air fed into the subterranean storage space at a value within the temperature limits of the ambient earth formation in which the air storage system is located.

6. System according to claim 1 including means for admixing metered doses of corrosion-resistant medium to fresh air being fed from above-ground to the subterranean air storage space.

7. System according to claim 1 wherein said means for withdrawing air from said air storage space is also used for feeding air to said storage space, said withdrawing and feeding means including a first conduit means in communication with said protective tube and extending out of said protective tube, said first conduit means being in communication with a gas turbine for supplying combustion air thereto from said subterranean air storage space and in communication with a supply of air to be stored, said feeding means including a second conduit means in communication with said annular space for feeding air to said annular space and a third conduit means between said first conduit means and said second conduit means for directing a partial flow of air from said first conduit means to said second conduit means as air is being fed to said storage tank through said first conduit means.

8. System according to claim 7 wherein said third conduit means includes a check valve permitting oneway flow from said first conduit means to said second conduit means. 7

9. System according to claim 7 wherein said third conduit means includes a control valve to meter the amount of partial flow of air being diverted from said first conduit means to said second conduit means.

10. System according to claim 8 wherein said second conduit means has a pipe supplying air to said second conduit means, whereby air is fed to said annular space both through said pipe and through said check valve in said third conduit means.

Claims

3. System according to claim 1 including a heat-insulating, corrosion-resistant lining disposed on the inner surface of said protective tube.

8. System according to claim 7 wherein said third conduit means includes a check valve permitting one-way flow from said first conduit means to said second conduit means.