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Title:
A GAS TURBINE SYSTEM
Document Type and Number:
WIPO Patent Application WO/2017/084876
Kind Code:
A1
Abstract:
A gas turbine system comprising a source (3) of ammonia and a source (1) of an oxygen-containing gas; a first combustion chamber (2) connected to receive ammonia, a hydrogen-rich gas stream (24) and oxygen-containing gas; a turbine (6) connected to receive an exhaust gas stream (26) from the first combustion chamber; and a second combustion chamber (7) connected to receive an exhaust gas (34) from the turbine, ammonia (28) and a hydrogen-rich gas stream (30).

Inventors:
BULAT, Ghenadie (29 Pavillion Gardens, Lincoln LN6 8BD, LN6 8BD, GB)
HUGHES, Timothy (16 Denchworth Road, Wantage OX12 7AU, OX12 7AU, GB)
MAY, Jonathan (22 Post Mill Close, North Hykeham, Lincoln LN6 9HL, LN6 9HL, GB)
WILKINSON, Ian (28 Marlborough Crescent, Long Hanborough, Witney OX29 8JR, OX29 8JR, GB)
Application Number:
EP2016/076453
Publication Date:
May 26, 2017
Filing Date:
November 02, 2016
Export Citation:
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Assignee:
SIEMENS AKTIENGESELLSCHAFT (Wittelsbacherplatz 2, München, 80333, DE)
International Classes:
F02C3/22; F02C3/28; F02C6/00; C01B3/04
Foreign References:
JP2015031215A2015-02-16
US20050037244A12005-02-17
JP2012255420A2012-12-27
Attorney, Agent or Firm:
MAIER, Daniel et al. (Postfach 22 16 34, München, 80506, DE)
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Claims:
CLAIMS :

1. A gas turbine system comprising:

- a source (3) of ammonia and a source (1) of an oxygen- containing gas;

a first combustion chamber (2) connected to receive ammonia, a hydrogen-rich gas stream (24) and oxygen- containing gas;

- a turbine (6) connected to receive an exhaust gas stream (26) from the first combustion chamber; and

- a second combustion chamber (7) connected to receive an exhaust gas (34) from the turbine, ammonia (28) and a hydrogen-rich gas stream (30) . 2. A gas turbine system according to claim 1 further comprising a first cracker chamber (5) arranged to receive ammonia from the ammonia source (3) and to supply a hydrogen- rich gas stream (24) to the first combustion chamber (2) . 3. A gas turbine system according to claim 1 or claim 2, further comprising a second cracker chamber (9) arranged to receive ammonia from the ammonia source (3) and to supply a hydrogen-rich gas stream (30) to the second combustion chamber ( 7 ) .

4. A gas turbine system according to claim 2 or claim 3 wherein temperature of the or each cracker chamber is regulated by mass control of a flow of exhaust gas (36) from the second combustion chamber (7) .

5. A gas turbine system according to any preceding claim, further comprising a heat exchanger (12) arranged to receive exhaust gas (36) from the second combustion chamber (7) . 6. A gas turbine system according to claim 5 wherein a steam turbine (13) is provided, operated by heat derived from the heat exchanger (12) . 7. A method for combustion of ammonia, comprising the steps of:

providing (1) an oxygen-containing gas to a first combustion chamber (2);

- providing ammonia (3) to the first combustion chamber (2); - providing a hydrogen-rich gas (24) to the first combustion chamber (2 ) ;

performing a first combustion in the first combustion chamber;

- supplying an exhaust gas (26) from the first combustion chamber to a second combustion chamber (7);

- supplying ammonia (28) to the second combustion chamber;

- supplying a hydrogen-rich gas (30) to the second combustion chamber;

- performing a second combustion in the second combustion chamber with an enhanced equivalence ratio.

8. A method for combustion of ammonia according to claim 7, wherein the enhanced equivalence ratio lies in the range 1.0

- 1.2.

9. A method according to claim 7 or claim 8 wherein the hydrogen-rich gas (24) supplied to the first combustion chamber is generated by cracking of ammonia. 10. A method according to any of claims 7-9 wherein the hydrogen-rich gas (30) supplied to the second combustion chamber is generated by cracking of ammonia.

11. A method according to claim 9 or claim 10 wherein the cracking is carried out at an elevated temperature, the elevated temperature being provided by a flow of exhaust gas (36) from the second combustion chamber.

12. A method according to any of claims 7-11, further comprising the step of removing waste heat from exhaust gas stream (36) from the second combustion chamber and recovering energy .

13. A method for extracting energy from ammonia, comprising performing combustion of ammonia according to any of claims

7-12, including the step of connecting a turbine (6) to receive the exhaust gas (26) from the first combustion chamber and providing exhaust gas (34) from the turbine (6) to the second combustion chamber (7), the flow of gas through the turbine (6) generating a mechanical output.

14. A gas turbine system substantially as described and/or as illustrated in the accompanying drawing.

15. A method for combustion of ammonia substantially described and/or as illustrated in the accompanying drawing

16. A method for extracting energy from ammonia substantially as described and/or as illustrated in the accompanying drawing.

Description:
A GAS TURBINE SYSTEM

The present invention relates to combustion of ammonia to release energy. In particular, the invention relates to operation of a gas turbine, fuelled by combustion of ammonia.

Known procedures for release of energy from ammonia by combustion of the ammonia require supply of ammonia, an oxygen-containing gas and hydrogen. The supply and storage of hydrogen is expensive and raises safety concerns, and the present invention avoids the need to store hydrogen gas. It is preferred to operate the procedure for release of energy from ammonia as efficiently as possible, with minimum waste of energy. It is preferred that no external heat sources or energy sources are required to operate the procedure for combustion of ammonia.

The present invention accordingly provides equipment and methods as defined in the appended claims.

In particular, the present invention provides a gas turbine system comprising a source of ammonia and a source of an oxygen-containing gas, a first combustion chamber connected to receive three gas streams: ammonia, a hydrogen-rich gas stream and oxygen-containing gas; a turbine connected to receive an exhaust gas stream from the first combustion chamber; a second combustion chamber connected to receive three gas streams: an exhaust gas from the turbine, ammonia and a hydrogen-rich gas stream.

The gas turbine system may further comprise a first cracker chamber arranged to receive ammonia from the ammonia source and to supply a hydrogen-rich gas stream to the first combustion chamber. This hydrogen-rich gas stream supplies the hydrogen required for combustion of ammonia without the need to provide and store hydrogen.

The gas turbine system may further comprise a second cracker chamber arranged to receive ammonia from the ammonia source and to supply a hydrogen-rich gas stream to the second combustion chamber. This hydrogen-rich gas stream supplies the hydrogen required for combustion of ammonia without the need to provide and store hydrogen.

A temperature of the, or each, cracker chamber may regulated by mass control of a flow of exhaust gas from the second combustion chamber. This provides temperature control without the need for an external heating source.

The gas turbine system may further comprise a heat exchanger arranged to receive exhaust gas from the second combustion chamber. A steam turbine may be provided, operated by heat derived from the heat exchanger.

The present invention also provides a method for combustion of ammonia, comprising the steps of providing an oxygen- containing gas to a first combustion chamber; providing ammonia to the first combustion chamber; providing a hydrogen-rich gas to the first combustion chamber; performing a first combustion in the first combustion chamber; supplying an exhaust gas from the first combustion chamber to a second combustion chamber; supplying ammonia to the second combustion chamber; supplying a hydrogen-rich gas to the second combustion chamber; and performing a second combustion in the second combustion chamber with an enhanced equivalence ratio. Equivalence ratio in effect is the stochiometric ratio . The hydrogen-rich gas supplied to the first combustion chamber may be generated by cracking of ammonia.

The hydrogen-rich gas supplied to the second combustion chamber may be generated by cracking of ammonia.

The cracking may be carried out at an elevated temperature, the elevated temperature being provided by a flow of exhaust gas from the second combustion chamber.

The method may further comprise the step of removing waste heat from exhaust gas stream from the second combustion chamber and recovering energy. The invention also provides a method for extracting energy from ammonia, comprising performing combustion of ammonia, and including the step of connecting a turbine to receive the exhaust gas from the first combustion chamber and providing exhaust gas from the turbine to the second combustion chamber, the flow of gas through the turbine generating a mechanical output.

The above, and further, objects, characteristics and advantages of the present application will become more apparent from consideration of the following description of particular embodiments, given by way of example only, wherein :

Fig. 1 schematically illustrates an embodiment of the present invention .

Fig. 1 shows a gas turbine system according to an exemplary embodiment of the present invention, which includes optional features. The essential features of the present invention are set out in the appended independent claims. In the illustrated embodiment, the gas turbine system comprises a source such as compressor 1 which provides an oxygen-containing gas such as air and passes it into a first combustion chamber 2. Ammonia 3 passes through a calibrated mass flow separator 4 where a portion of the mass flow is passed directly to the first combustion chamber 2 and a second portion is passed to a cracker chamber 5. The cracker chamber 5 contains a catalyst (Ru, Rh, Pt, Pd or similar) which promotes the decomposition of ammonia N¾ into a hydrogen-rich gas mixture comprising nitrogen, hydrogen and other constituents. The degree of decomposition is controlled by varying the temperature of the ammonia and the catalyst. Elevated temperatures of ammonia and catalyst may be achieved by heat exchange with an exhaust gas flow 20 from a second combustion chamber 7, to be described below. The elevated temperature may be controlled by varying the mass flow of ammonia through the heat exchanger and mass flow of the exhaust gas 20 through the catalyst bed of the first cracker chamber .

Ammonia stream 22 and hydrogen-rich stream 24 are injected into first combustion chamber 2 where combustion takes place producing heat and an exhaust gas flow 26. Due to incomplete combustion of the ammonia (N¾) the exhaust gas flow will have high levels of NO x . The exhaust gas flow 26 is supplied to a turbine 6 where work is transferred to a shaft or similar, to produce a mechanical output.

The exhaust gas flow 26 leaving the turbine is hot and is routed to a second combustion chamber 7. Ammonia 3 is flowed into a second calibrated flow separator 8 where a portion of the mass flow of ammonia is passed directly to the second combustion chamber 7 as an ammonia stream 28. A second portion is passed to a second cracker chamber 9. The cracker chamber 9 contains a catalyst (Ru, Rh, Pt, Pd or similar) which promotes the decomposition of N¾ into nitrogen, hydrogen and other constituents into a hydrogen-rich stream 30. The degree of decomposition is controlled by varying the temperature of the gases and catalyst within the second cracker chamber 9. Elevated temperature in the second cracker chamber 9 may be achieved by heat exchange with an exhaust gas flow 32 from the second combustion chamber 7. The temperature may be controlled by varying the mass flow of exhaust gas flow 32 through the heat exchanger and mass flow of ammonia through the catalyst bed of the cracker chamber.

The ammonia stream 28 and the hydrogen-rich stream 30 are injected into the second combustion chamber 7 where they are combusted. The combustion in the second combustion chamber is performed with an enhanced equivalence ratio typically 1.0 -

I.2, meaning that an excess of ammonia is present. The enhanced ratio ensures that the combustion produces a significant proportion of N¾ ~ ions. These N¾ ~ ions combine with the NO x in the exhaust stream 34 from the turbine 6 to produce 2 and ¾0, thereby removing the NO x from the exhaust stream.

The exhaust gas 36 from the 2nd combustion chamber 7 flows through a calibrated flow separator 10 so that a portion of the mass flow is routed to another calibrated flow separator

II. By control of calibrated flow separators 10 and 11, mass flow is manipulated so that the first and second cracker chambers 5 and 9 are at the required temperatures. Preferably, a heat exchanger loop 12 is used to remove waste heat from exhaust stream 36 and recover energy, for example by boiling water to rotate a steam turbine 13. The invention accordingly provides an ammonia-powered turbine, allowing energy stored as ammonia to be recovered into a mechanical output at turbine 6. By use of dual combustion chambers, nitrogen oxides NO x are removed from the exhaust stream. Combustion in the second combustion chamber is performed at an appropriate equivalence ratio to allow the formation of N¾ ~ ions, which combine with NO x in the exhaust gas from the first combustion chamber. The equivalence ratio may be achieved by appropriate selection and control of the temperature of cracker chambers 5, 9. The temperature of the cracker chambers may in turn be controlled by controlling the flow of an exhaust gas. The process is energy efficient in that the required heating of cracking chambers to generate a hydrogen-rich stream from ammonia is provided by an exhaust stream from ammonia combustion. This avoids the need for separate provision and storage of a heating source such as hydrogen gas, or provision of heating by other means such as electrical heating .

Energy present in the temperature of final exhaust gas may be recovered into mechanical output by operation of a steam turbine or other energy-recovery arrangements.