WO2015106316A1

WO2015106316A1 - Gas turbine system and method of operation

Info

Publication number: WO2015106316A1
Application number: PCT/AU2015/050007
Authority: WO
Inventors: Peter Jones
Original assignee: Peter Jones
Priority date: 2014-01-16
Filing date: 2015-01-12
Publication date: 2015-07-23
Also published as: JP2015132249A; JP5584836B1

Abstract

A gas turbine system with a turbine, a combustor for adding fuel to a working fluid and igniting the fuel to produce combustion gases that expand to drive the turbine and a steam ejector for introducing steam and compression to the working fluid, wherein the steam ejector and combustor are incorporated into an ejector combustor unit which has a suction chamber in which a mixture of fuel, the working fluid and steam are entrained and accelerated, a throat where the mixture is ignited and a divergent diffuser nozzle in communication with the turbine, through which the combusted mixture increases in pressure in a process of pressure gain combustion.

Description

GAS TURBINE SYSTEM AND METHOD OF OPERATION

RELATED APPLICATION

[0001] This application claims priority from Japanese Patent Application No. 2014- 05532. the contents of which are incorporated in entirety by reference.

TECHNICAL FIELD

[0002] The present invention generally relates to a gas turbine, BACKGROUND

[0003] A gas turbine is an apparatus that produces rotational work, through the manipulation of a ga phase working fluid by a thermodynamic cycle. The basic stages of the thermodynamic cycle common to ail gas turbines is an initial compression stage to increase the pressure of the working fluid, a combustion stage where the temperature of the compressed gas is increased, and an expansion stage where the hot compressed gas is introduced to a turbine. The expansion of gas across this turbine creates rotational work.

[0004] The turbine may be mechanically coupled to a rotary compressor by a connecting shaft such that a portion of work produced by the turbine is used to compress the working fluid. Most commercially available gas turbines use an axial compressor, though the use of centrifugal and other compressors is also known to the art.

[0005] Many modifications and improvements have been made to gas compressors over the decades, improving their function and efficiency greatly. The present invention offers such an improvement.

[0006] The reference i thi specification to an prior publication (or information derived from it), or to any matier which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publieation (o information deri ed from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

OBJECT OF THE INVENTION

[0007] The present invention seeks to provide increased efficiency for a gas turbine, SUMMARY OF THE INVENTION

[0008] lit accordance with the present invention, there is provided a gas turbine system with a turbine, eornbustor for adding fuel to a working fluid and igniting the fuel to produce combustion gases that expand to drive the turbine and steam ejector for introducing steam and compression to the working fluid.

[0009] Preferably, the system further includes a mechanical compressor for compressin the working fluid.

[0010] Preferably, the steam ejector is coupled to an inlet of the mechanical compressor.

[001 1] Alternatively, the steam ejector is coupled to the eombustor, downstream of the mechanical compressor.

[0012] Preferably, the system further includes multiple mechanical compressor stages, wherein the steam ejector is coupled to an inlet of a first mechanical compressor of the multiple mechanical compressor stages.

[0013] Alternatively, the system further includes multiple compresso stages, wherein the steam ejector is coupled between an outlet of a first mechanical compressor and an inlet of a second mechanical compressor,

[0014] I another alternative, the system further includes multiple mechanical compressor stages and one or more steam ejectors coupled at one or more locations before the mechanical compressor stages, between the mechanical compressor stages or after the mechanical compressor stages. 1_.00.15] P ferably, the system further includes multiple combustion stages for driving the turbine .

[0016] Preferably, one or more steam ejectors are provided upstream of each combustion stage.

[0017] Preferably, an exhaust of a first one of the multiple combustion stages is coupled upstream of a second one of the multiple combustion stages, whereby the exhaust from the first combustion stage forms the working fluid for the second combustion stage.

|0018] Preferably, the exhaust, of the first combustion stage is coupled into an inlet of the steam ejector associated with the second combustion stage.

[0019] Preferably, a mechanical compressor is provided upstream of the steam ejector associated with the first combustion stage.

[0020] Preferably, the system further includes a boiler thai extracts heat energy from exhaust gase of the turbine and generates steam used in the steam ejector.

[0021 ] Preferably, multiple steam ejectors use steam from the boiler.

[0022] Preferably, one or more steam generators are coupled to an inlet of the or eac steam ejector for supplemental steam, if required.

[0023] Preferably, the steam ejector and eombustor are incorporated into an ejector eombustor unit which has a suction chamber in which a mixture of fuel, the working fluid and steam are entrained and accelerated, a throat where the mixture is ignited and a divergent diffuser nozzle in communication with the turbine, through which the combusted mixture increases in pressure.

[0024] Preferably, the system includes multiple combustion stages for driving the turbine, with an associated multiple ejector eombustor units. 1_.0025] P ferably, an exhaust of a first one of the combustion stages is coupled upstream of a second one of the combustion stages, whereby the working fluid of the ejector conibustor unit of the second combustion stage include the exhaust gases from the first combustion stage and the steam for each ejector combustor unit is generated from exhaust heat from the second combustor stage.

[0026] In another aspect, there is provided a method of operating a gas turbine that uses upstream compression of a working iluid and a downstream combustion stage to ignite a mixture of compressed working fluid and fuel to drive a turbine, wherein at least a. portion of a compression duty is performed by a steam ejector.

[0027] Preferably, exhaust heat from the turbine is used to raise steam for the steam ejector,

[0028] Preferably, substantially all of the air compression duty is performed by one or more steam ejectors.

[0029] Preferably, the portion of the compression duty is performed by one or more steam ejectors and the remaining portion is performed by one or more mechanical compressors,

[0030] Preferably, the steam raised will meet at least a portion of a steam duty of the steam ejector,

[0031] Preferably, steam for the steam ejector is drawn from one or more additional steam generators for supplemental steam, if required.

(0032] Preferably, combustion, steam injection and ignition is performed in an ejector combustor unit, where the steam, working fluid and fuel i entrained and compressed, and ignited in a throat of the ejector combustor unit to expand to a higher pressure, then enter into and drive the turbine.

[0033] Preferably, the combustion occurs over multiple combustion stages, each used to drive the turbine, and wherein an ejector combustor unit is used with each combustion stage.

[0034] Preferably, the exhaust from a first one of the multiple combustion stages provides the working fluid for a second one of the multiple combustion stages.

[0035] Preferably, one or more mechanical compressors are used to compress the working fluid upstream of the or each ejector compressor units.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention is described, by way of non-limiting example only, with, reference to the accompanying drawings, in which:

[0037] Figure 1 illustrates a prior art gas turbine;

[0038] Figure 2 illustrates a gas turbine system where a steam ejector is used to pre- compress air pri r to a rotary compressor;

[0039] Figure 3 illustrates a gas turbine system with two mechanical compression stages and an intermediate steam ejector;

[0040] Figure 4 illustrates a gas turbine system where a steam ejector is used to further compress air following a rotary compressor;

[0041 ] Figure 5 illustrates a gas turbine system, similar to that shown in Figure 4, where the steam ejector and combustion stage have been integrated into a single ejecto combustor unit;

[0042] Figure 6 illustrates a gas turbine system the entire compression duly is performed by an ejector combustor unit;

[0043] Figure 7 illustrates a gas turbine system with multiple combustion stages; and [0044] Figure 8 illustrates a gas turbine system, similar to that shown in Figure 7, with a mechanical compressor.

DETAILED DESCRIPTION

10045] In the Figures and the accompanying description, like reference numerals will be used t identify like parts.

[0046] Also throughout the description, working fluid will he described primarily as air. However, it should be understood the workin fluid can be any suitabl fluid and reference to air is to be taken to be a reference to any other suitable working fluid.

[0047] Referring firstly to Figure 1, a prior art gas turbine 1 is diagraramatically iliustrated as including a rotar mechanical compressor 2 mounted to a. shaft 3 of a turbine 4. The compressor 2 has an inlet 5 and working fluid in the form or air is drawn into the inlet 5 for compression. Hot compressed air is transferred from an outlet 6 of the compressor 2 to a downstream combustor 7, where fuel from a fuel inlet 8 in added to form a fuel/air mixture. The mixture is ignited in the combustor 7 to cause expansion of hot, pressurised gases across the turbine 4, in order to drive rotation of the turbine 4. Hot exhaust gases exit the turbine 4 via an exhaust 8.

[0048] The rotational work created by expansion of gases across the turbine 4 can be used for a variety of purposes,, for example, to drive the motion of a vehicle or to power a generator to produce electricity,

[0049] The gas turbine 1 of Figure 1 represents a simple, single stage ga turbine, where the compressor 2 is mechanicall coupled to the turbine 4 such that a portion of the rotational work produced by the turbine 4 powers the rotary compressor 2 and the compressor 2 provides the entire compression duty requirements of the gas turbine 1 ,

[0050] Referring now to Figure 2, a gas turbine system 10 is shown which includes similar components of a mechanical compressor 2, a combustor 7 and a turbine 4, However, the system 10 also includes a steam ejector 11 that contributes at least a portion of the compression duty requirements of the system 10.

[0051] The steam ejector 1 1 i a device tha at least partiall compresses the working fluid by using high pressure steam to entrain the working fluid into a suction chamber 12. The steam and working fluid pass throug a throat 13 of the ejecto 11 and then expand across a diffuser nozzle 14. As the steam expands, a fog of microscopic water droplets can be f canned.

[0052] The outlet 15 of the steam ejector 11 is coupled to the inlet 5 of the compressor 2. As such, the steam droplets are introduced into the compressor 2. The water droplets evaporate as the air is subsequently compressed by the mechanical compressor 2. This provides evaporative cooling to the air as it is compressed, which reduces the power required to compress the air.

[0053] As a result, the system operates more efficientl compared to the ga turbine of Figure 1 as less rotational work from the turbine i required in order to drive the compressor.

[0054] The stream used in the steam ejector 11 is raised by a boiler 16 that utilises waste heat energy from hot exhaust gases generated by the turbine 4. in particular, the boiler 16 is shown coupled between the exhaust 17 of the turbine 4 and a vent 18 where cooled exhaust gases exit the system 10.

[ 0055] The use of heated exhaust gases to generate steam for the steam ejector 1 1 brings additional efficiencies to the system 10 as energy from waste heat is used to assist the compression duty requirements of the system 1 .

[0056] It should, however, be appreciated the steam could be raised by a different boile (not shown) not connected to the exhaust 17 or ma be raised in combination with one or more additional steam generators (also not shown) fired by lower cost fuels compared to that burnt by the gas turbine system 10. Such fuels can be solid fuels which produce as when burnt and are therefore not otherwise able to be used to fuel and drive the gas turbine 4. Maximum steam temperatures, particularly using additional steam generators can be as high as 60(rc.

[0057] Figure 3 shows a gas turbine system. 20 similar to that of Figure 2, except with multiple mechanical compressions stages 21 , 22, In this case, the steam ejector 1 1 acts as an intermediate compressor 23 and is coupled between a first mechanical compresso 2 and a second mechanical compressor 24. As such, the working fluid, in the form of air, is initially introduced into the inlet 5 of the first compressor 2 and the compressed working fluid is then output to an inlet 25 of the steam ejector 1 1 which further compresses the working fluid and disperses water droplets throughout the air. The mixture of steam and air is then transferred to the inlet 26 of the second compressor 24 for subsequent compression, which increases the heat of the mixture and causes the droplets to evaporate, thus cooling the air. In effect, the intermediate ejector 1.1 provides both a cooling potential and a compression stage in its own right. This has the advantage of allowing for further compression b the second compressor 24 t produce higher pressure air. The alternatin use of rotary compressors 2, 24 and a steam ejector 1.1 can be repeated further, allowing for an even greater degree of air compression.

[0058] The system 20 of Figure 3 is suited to applications where high pressure air is required. The steam ejector 11 enables the fo of cooling microscopic water droplets to be introduced into the second mechanical compression stage 22, to provide the benefits of evaporative cooling during compression of the second compressor 24.

[0059] As with the system 10 of Figure 2, the steam ejector .1 1 is coupled to a boiler 16 that raises stream from heat from the exhaust: .17 of the turbine 4.

[0060] Referring now to Figure 4, another gas turbine system 30 is shown that i generally similar to the system 10 described with reference to Figure 2, except the steam ejector 11 is connected downstream of the compressor 2, between the compressor 2 and the combustor 7,

[0061 ] As such, air is initially compressed by the rotary compressor 2 before further compression by a steam ejector 11, Extra heat, can also be introduced by the steam passing through the steam ejector 11. As with the systems 10, 20 described with reference to Figure 2 and 3, the steam can be raised by the boiler 16 or one or more additional steam generators may be employed to supplement the required steam duty of the system 30, as required.

[0062] The location of the steam ejector 1 1 , betwee the compresso 2 and the eombustor 7, means the turbine 4 can operate at higher air pressure than that obtained by a mechanical compressor 2 alone.

[0063] As may be .appreciated from the systems 10, 20 and 30 described above, the steam ejector 11 may be located upstream of the mechanical compressor % downstream of the mechanical compressor 2 or intermediate mechanical compressor stages 21_» 22. In each location, the steam ejector 1 1 can provide advantages of increased compression and operating efficiencies. It is envisioned that one or more steam ejectors 11 could be used at onl one or at multiple of the above locations. Further, each steam ejector 1 1 may have multiple steam jets, multiple suction chambers and/or multiple steam ejectors could be mounted in series of parallel, as required.

[0064] Referring now to Figure 5, a gas turbine system 40 generally similar t system 30 of Figure 4 is disclosed. In this case, however, the functionality of the steam ejector 1 1 and the eombustor ? have been integrated into a single ejector eombustor unit 41,

[0065] The ejector eombustor unit 41 has a suction chamber 42 in which a mixture of fuel, the working fluid and steam are entrained and accelerated, a throat 43 where the .mixture is ignited and accelerates, and a divergent diffuser 44 where the pressure rises in a process of pressure gain combustion. The combusted mixture exits the divergent diffuser 44 to dri ve the turbine 4.

(0066] The ejector eombustor unit 41 operates on the same principle as a ramjet in so far as heat and expansion resulting from combustion of the air/fuel mixture will further accelerate gase which will rise to a higher pressure for expansion across the turbine.

[0067] As such, the unit 41 allows greater material throughput and higher operating pressures to be achieved by the combination of the steam ejector and pressure gain combustions as compared with use of the mechanical compressor 2 alone.

[0068] Referring now to Figure 6 a gas turbine system 50 is shown that is an adaption of the system 40 described with reference to Figure 5, where the entire compression duty of the gas turbine 4 is performed by an ejector combusto 41 , without the aid of a rotary compressor. As such, the system 50 avoids the high capital cost of a mechanical compressor. However, large quantities of steam may be required for this arrangemen and the steam from the boiler 16 coupled to the exhaust 1? of the turbine 4 may need to be supplemented by additional steam generators.

|0069] Referring now to Figure 7 a gas turbine system 60 is shown which has multiple combustion stages 61 , 62 for driving the turbine 4, which is divided into a high pressure turbine 63 and a low pressure turbine 64. The system 60 includes associated multiple ejector combustor units 41, 65 and each of the units 41, 65 is fed with high pressure steam from the common boiler 16 that raises the required steam from hot exhaust gases from the turbine 4. An exhaust 66 of the first combustion stage 61 is coupled upstream of the second combustion stage 62, whereby the working fluid of the ejector combustor unit 65 of the second combustion stage 62 includes the exhaust gases from the first combustion stage 61 and the steam for each ejector combustor unit 41, 65 is generated from exhaust heat from the second combustor stage 62,

[0070] The system allows for partial expansion across the high pressure turbine 63, followed by a second stage of combustion before further expansion across the final, lo pressure turbine 64. The system 60 thereby subjects the working fluid to two separate thermodynamic cycles in series. By locating the ignition in the throat of the unit 65, simultaneous temperature and pressure rises can be obtained so the second combustion stage 62 of the of the system 60 produces greater power.

[0071] Figure 8 shows an alternative system 70 to that of Figure 7, where a rotary mechanical compressor 2 used prior to the initial ejector combustor 41 in the first combustion stage 1 of the two cycle t urbine arrangement.

[0072] A benefit of this invention is that the energy consumption of a mechanical compressor can be reduced and the mass flow of gases through the turbine will be increased by admixture of the steam with the air. This will result in reduced fuel consumption by the gas turbine to produce the same amount of useful work. In addition, the ejector may in some circumstances be used as a substitute to a mechanical compressor such that the steam ejector will provide a simple and low cost device which performs the task of more costly equipment so capital costs should also be able to be reduced.

[0073] More broadly, it may be appreciated the invention claimed in this patent application is the installation of steam elector to perform or assist air compression in gas turbines. The steam may be raised in a boiler heated by the hot exhaust gases of the gas turbine and this steam may be supplemented by an external boiler. The ejector may be used in the manner as it is normally used in industry as a compressor. It can be used to pre- compress the air prior to the mechanical compressor, be located between compressor stages or after the compressor and before the combustor or it may perform the entire air compression duty itself. A steam ejector ma be used at the location of the combustor, in the form of an ejector combustor unit, in which a high velocity air and steam mixture in the throat of the unit is accelerated by the heat released by ignited fuel so as the velocit reduces in the diffuse!" the final pressure rises to a higher value. The steam ejector or ejectors will reduce the power used by the mechanical compressor and increase the mass flow of gas through the turbine. The overall effect will be to increase power output and reduce fuel consumption.

[0074] Many modifications to and arrangements of the present invention will be apparent to those skilled in the art without departing from the scope of the present invention. - X 1.i "ί, -

LIST OF PARTS

1. Gas turbine

Compressor

.

4. Turbine

5. Inlet

6. Outlet

7. Combustor

8. Exhaust

9.

10. Gas turbine system

11. Ejector

12. Suction chamber

13. Throat

14. Diffuser nozzle

15. Outlet

16. Boiler

17. Exhaust

18. Vent

19.

20. Gas turbine system

21. Compressions stage

22. Compression stage

23. Intermediate compressor

24. Second compressor

25. Inlet

Tr

Ό. 1 1t1l KoMt

30. Gas turbine system

40. Gas turbine sy stem

41 . Injector

42. Suction chamber

43, Throat 44. Diffuser nozzle

50. System

60. System

61. Combustion stage

62. Combustion stage

63. High pressure turbine

64. Low pressure turbine

65. Ejector combustor unit

66. Exhaust

70. Gas turbine system

Claims

- 1.4 - CLAIMS:

1. A gas turbine system with a turbine, a combustor for adding fuel to a working fluid and igniting the fuel to produce combustion, gases that expand to drive the turbine and a steam ejector for introducing steam and compression to the working fluid, wherein the steam ejector and combustor are incorporated into an ejector combustor unit which has a suction chamber in which a mixture of fuel, the working fluid and steam are entrained and accelerated, a throat where the mixture is ignited and a divergent diffuser nozzle in communication with tire turbine, through which the combusted mixture increases in pressure in a process of pressure gain combustion.

2. The gas turbine system of claim 1 , further including multiple combustion stages for chiving the turbine, with an associated multiple ejector combustor units.

3. The gas turbine system of claim 2, wherein an exhaust of a first one of the combustion stage is coupled upstream of a second one of the combustion stages, whereby the working fluid of the ejector combustor unit of the second combustion stage includes exhaust gases from the first combustion stage and the steam for each ejector combustor unit is generated from exhaust heat from the second combustor stage.

4. A method of operating a gas turbine that uses compression of a working fluid and combustion to ignite a mixture of compressed working fluid and fuel to drive a turbine, wherein combustion, steam injection and ignition is performed in an ejector combustor unit, where the steam, working fluid and fuel is entrained and compressed, and ignited in a throat of the ejector combustor unit to expand to a higher pressure in. a process of pressure gain combustion, then ente into and drive the turbine.

5. The method of claim 4, wherein the combustion occurs over multiple combustion stages, each used to drive the turbine, and wherein an ejector combustor unit is used with eac combustion stage,

6. The method of claim 5, wherein exhaust from a first one of the multiple combustion stages provides the working fluid for a second one of the multiple combustion stages.

7. The method of claim 6, wherein one or more mechanical compressors are used to compress the working fluid upstream of the or each ejector compressor units.