A GAS TURBINE SYSTEM

Abstract

A gas turbine system has a source of ammonia and a source of an oxygen-containing gas, a first combustion chamber connected to receive ammonia, a hydrogen-rich gas stream and oxygen-containing gas, a turbine connected to receive an exhaust gas stream from the first combustion chamber; and a second combustion chamber connected to receive an exhaust gas from the turbine, ammonia and a hydrogen-rich gas stream.

Claims

1-16. (canceled)

17. A gas turbine system comprising: a source of ammonia and a source of an oxygen-containing gas; a first combustion chamber connected to receive a stream of ammonia gas, a gas stream comprising hydrogen gas, and an oxygen-containing gas; a turbine connected to receive an exhaust gas stream from the first combustion chamber; a second combustion chamber connected to receive an exhaust gas from the turbine, a stream of ammonia gas, and a gas stream comprising hydrogen gas; a source of ammonia connected to the first combustion chamber and providing the stream of ammonia gas to the first combustion chamber; said source of ammonia also being connected to the second combustion chamber and providing the stream of ammonia gas to the second combustion chamber; and a first cracker chamber arranged to receive ammonia gas from the source of ammonia gas and to supply the gas stream comprising hydrogen gas to the first combustion chamber.

18. A gas turbine system as claimed in claim 17 further comprising a second cracker chamber arranged to receive ammonia gas from the ammonia gas source and to supply the gas stream comprising hydrogen gas to the second combustion chamber.

19. A gas turbine system as claimed in claim 18 wherein a temperature of at least one of said first cracker chamber and said second cracker chamber is regulated by mass control of a flow of exhaust gas from the second combustion chamber.

20. A gas turbine system as claimed in claim 17 further comprising a heat exchanger arranged to receive exhaust gas from the second combustion chamber.

21. A gas turbine system as claimed in claim 20 comprising a steam turbine operated by heat derived from said heat exchanger.

22. A method for extracting energy from ammonia, comprising the steps of: providing an oxygen-containing gas to a first combustion chamber; providing ammonia to the first combustion chamber; providing a gas stream comprising hydrogen gas to the first combustion chamber; performing a first combustion in the first combustion chamber that produces an exhaust gas; providing said exhaust gas from said first combustion chamber to a second combustion chamber; supplying ammonia to the second combustion chamber; supplying a stream comprising hydrogen gas to the second combustion chamber; performing a second combustion in the second combustion chamber with an enhanced equivalence ratio; generating the gas stream comprising hydrogen gas, which is supplied through the first combustion chamber, by tracking of ammonia; and 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 and thereby causing a flow of gas through the combustion to generate a mechanical output.

23. A method for extracting energy from ammonia as claimed in claim 22 wherein said equivalence ratio is in a range between 1.0 and 1.2.

24. A method as claimed in claim 22 comprising generating the gas stream comprising hydrogen gas to the second combustion chamber by cracking of ammonia.

25. A method as claimed in claim 24 comprising conducting said cracking of ammonia at an elevated temperature provided by a flow of exhaust gas from the second combustion chamber.

26. A method as claimed in claim 22 comprising removing waste heat from an exhaust gas stream from the second combustion chamber, and recovering energy from said waste heat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The single figure schematically illustrates an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The figure shows a gas turbine system according to an exemplary embodiment of the present invention, which includes optional features in addition to the essential features described below.

[0016] 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) that promotes the decomposition of ammonia NH.sub.3 into a hydrogen-rich gas mixture containing 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.

[0017] 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 (NH.sub.3) the exhaust gas flow will have high levels of NO.sub.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.

[0018] 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) that promotes the decomposition of NH.sub.3 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.

[0019] 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 1.0-1.2, meaning that an excess of ammonia is present. The enhanced ratio ensures that the combustion produces a significant proportion of NH.sub.2- ions. These NH.sub.2- ions combine with the NO.sub.x in the exhaust stream 34 from the turbine 6 to produce N.sub.2 and H.sub.2O, thereby removing the NO.sub.x from the exhaust stream.

[0020] 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 11. 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.

[0021] 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.

[0022] The invention accordingly provides an ammonia-powered turbine, allowing energy stored as ammonia to be recovered into a mechanical output at turbine 6.

[0023] By use of dual combustion chambers, nitrogen oxides NOx are removed from the exhaust stream. Combustion in the second combustion chamber is performed at an appropriate equivalence ratio to allow the formation of NH.sub.2- ions, which combine with NOx 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.

[0024] The temperature of the cracker chambers may in turn be controlled by controlling the flow of an exhaust gas.

[0025] 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.

[0026] 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.

[0027] Although modifications and changes may be suggested by those skilled in the art, it is the intention of the Applicant to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of the Applicant's contribution to the art.