EP4638927A1

EP4638927A1 - A gas turbine auxiliary system for nh3 conditioning

Info

Publication number: EP4638927A1
Application number: EP23833606.9A
Authority: EP
Inventors: Sergio GHEZZI; Giovanni SARTI; Christian Romano; Alessio Miliani; Egidio PUCCI
Original assignee: Nuovo Pignone Technologie SRL
Current assignee: Nuovo Pignone Technologie SRL
Priority date: 2022-12-23
Filing date: 2023-12-22
Publication date: 2025-10-29
Also published as: AU2023411292A1; CN120265870A; CL2025001579A1; KR20250124367A; JP2025539656A; WO2024132218A1

Abstract

A system for generating power using a gas turbine is disclosed. The system comprises an ammonia-cracking device, to convert at least part of a NH₃ stream into H₂ and N₂, to realize a gas NH₃/H₂/N₂ mixture that allows operating the gas turbine in every condition. In one aspect, the NH₃ stream is splitted into a first NH3 stream that is cracked into H₂ and N₂ through a cracking to obtain a H₂ and N₂ stream and a second NH₃ stream that is directed to the gas turbine through a bypass line.

Description

A gas turbine auxiliary system for NH conditioning

Description

TECHNICAL FIELD

[0001] The present disclosure concerns a system for generating power using a gas turbine, wherein the system comprises an ammonia-cracking device. Embodiments disclosed herein specifically concern a gas turbine auxiliary system for NH3 conditioning, wherein a fuel skid processes an ammonia input stream in order to realize a NH3/H2/N2 gas mixture that allows operating the gas turbine in every condition. Also disclosed herein are methods for optimizing gas turbine operation and controlling NO_X emission from the gas turbine in every gas turbine condition.

BACKGROUND ART

[0002] Gas turbines are commonly used to generate power at power stations by combusting fuel therein. In particular, the basic operation of a gas turbine is a Brayton cycle with air as the working fluid: atmospheric air flows through a compressor that brings it to a higher pressure; energy is then added by injecting fuel into the air in a combustion chamber and igniting it so that a combustion generates a high-temperature flow; this high-temperature pressurized gas enters a turbine, producing a shaft work output in the process, used to drive the compressor; the unused energy comes out in - the exhaust gases that can be repurposed for external work, such as directly producing thrust in a turboj et engine, or rotating a second, independent turbine (known as a power turbine) that can be connected to a fan, propeller, or electrical generator. The purpose of the gas turbine determines the design so that the most desirable split of energy between the thrust and the shaft work is achieved. The fourth step of the Brayton cycle (cooling of the working fluid) is omitted, as gas turbines are open systems that do not reuse the same air.

[0003] Commonly used fuels includes natural gas, propane, diesel, biogas and biodiesel. One of the main problems associated with combusting fuels such as these in gas turbines is the resultant production of carbon dioxide (CO2) gas. Increased CO2 levels in the atmosphere are detrimental to the environment and are a known cause of global warming. As such, there is a need to provide fuels for use in gas turbines which do not generate CO2 upon combustion, or from which CO2 must be removed prior to combustion.

[0004] Carbon-free fuels include ammonia and hydrogen. However, both ammonia and hydrogen have some problems associated with their direct use as fuel in a gas turbine. The main problem associated with the direct use of ammonia as fuel in gas turbines is that during the combustion process ammonia is oxidized to nitrogen oxides NO_X, a polluting agent contributing to acid rain and global warming. Additionally, due to the low heat content and low reactivity of ammonia with oxygen, the ammonia combustion within the gas turbine presents stability issues (blow-out) over the entire range of the gas turbine operating conditions. On the other hand, even if the combustion of hydrogen still produces NO_X polluting agents, stability issues (blow-out) disappear. Nevertheless, a number of problems are associated with the use of hydrogen as fuel, including storage problems and the fact that hydrogen is an extremely flammable gas. The availability of N2 as inert within the combustion process could help to reduce NO_X emissions depending on the type of flame realized in the gas turbine combustor.

[0005] CN107288780A discloses a system for generating power using a gas turbine, wherein ammonia is used as fuel. Upstream the combustion chamber, ammonia is partly decomposed to generate hydrogen within an ammonia cracking device to provide a fuel mixture containing hydrogen and ammonia. Since the fire point of hydrogen is lower than that of ammonia, hydrogen is combusted in the combustion chamber first to release heat to ignite ammonia in the combustion chamber. As a consequence, hydrogen can accelerate the combustion process and, accordingly, the combustion performance of ammonia fuel is improved. In conclusion, the amount of hydrogen supplied is functional to NH3 ignition. However, the system disclosed in CN107288780 does not completely overcome the environmental problems due to the formation of nitrogen oxides due to oxidation of ammonia during the combustion process.

[0006] US11084719B2 discloses a process for generating power using a gas turbine, comprising the steps of: (i) vaporizing and pre-heating liquid ammonia to produce preheated ammonia gas; (ii) introducing the pre-heated ammonia gas into an ammonia- cracking device suitable for converting ammonia gas into a mixture of hydrogen and nitrogen; (iii) converting the pre-heated ammonia gas into a mixture of hydrogen and nitrogen in the device; (iv) cooling the mixture of hydrogen and nitrogen to give a cooled hydrogen and nitrogen mixture; (v) introducing the cooled hydrogen and nitrogen mixture into a gas turbine; and (vi) combusting the cooled hydrogen and nitrogen mixture in the gas turbine to generate power. US11084719B2 also discloses embodiments where the composition of the mixture of hydrogen and nitrogen exiting the ammonia cracking device can be adjusted using purification techniques. However, the composition of the output mixture from the cracking process can be far from optimal for the GT operational requirement.

[0007] US11156168B2 discloses a gas turbine plant that is provided with a gas turbine, a heating device, a decomposition gas line, and a decomposition gas compressor. The heating device heats ammonia and thermally decomposes the ammonia to convert the ammonia into decomposition gas including hydrogen gas and nitrogen gas. The decomposition gas line sends the decomposition gas from the heating device to the gas turbine. The decomposition gas compressor increases the pressure of the decomposition gas to a pressure equal to or higher than a feed pressure at which the decomposition gas is allowed to be fed to the gas turbine. US11156168B2 also discloses a control device that adjust the ratio of the flow rate of the decomposition gas to the flow rate of the whole fuel gas (which includes the natural gas and the decomposition gas). The control of such ratio allows obtaining and regulating a mixture of decomposition gas and natural gas to the combustion chamber. However, combusting natural gas still produces a high level of carbon dioxide, which is released to the atmosphere or requires additional carbon capture systems.

[0008] In conclusion, the prior art solution approaches either negatively affect the operation costs of the system or have an adverse environmental impact. Accordingly, an improved system generating power using a gas turbine and ammonia as fuel to address the issues of real time conditioning NH3 to realize a gas NH3/H2/N2 mixture that allows operating the gas turbine in every condition would be beneficial and would be welcomed in the technology. NH3 conditioning needs to be pursued flexibly and regulated at different level along the path towards the turbine, so it is felt the need of a system capable to tune and deliver fuels to the gas turbine at different stages, to improve performances but also abate NO_X emission. More in general, it would be desirable to provide methods and systems adapted to more efficiently address problems entailed by providing an auxiliary system for NH3 conditioning to realize a gas NH3/H2/N2 mixture that allows operating the gas turbine in every condition. SUMMARY

[0009] In one aspect, the subject matter disclosed herein is directed to an improved system generating power using a gas turbine and ammonia as fuel wherein the system comprises an ammonia-cracking device, to convert ammonia into hydrogen and nitrogen to be delivered to the gas turbine, and an ammonia by-pass line, to direct a portion of the ammonia directly to the gas turbine, the system further comprising a plurality of flow valves, controlled by an auxiliary control unit, the flow valves including a gas flow valve arranged downstream the ammonia cracking reactor and/or a gas NH3 bypass stream flow valve arranged along a gas NH3 feed line connected downstream the NH3 bypass stream line. Embodiments disclosed herein specifically concern a gas turbine auxiliary system for NH3 conditioning, wherein a fuel skid processes an ammonia input stream in order to realize a gas NH3/H2/N2 mixture that allows operating the gas turbine in every condition.

[0010] In another aspect, the subject matter disclosed herein is directed to a method of generating power using a gas turbine and ammonia as fuel. The ammonia conditioning auxiliary system is operated through control routines as functions of GT parameters, Combustion parameters and NOx requirements at the GT exhaust.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Fig. l illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a first embodiment;

Fig. 2 illustrates a block diagram of the control architecture of the power generating system of Fig. 1;

Fig.3 illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a second embodiment;

Fig. 4 illustrates a block diagram of the control architecture of the power generating system of Fig. 3; Fig. 5 illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a third embodiment;

Fig. 6 illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a fourth embodiment;

Fig. 7 illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a fifth embodiment; and

Fig. 8 illustrates a schematic of a power generating system using a gas turbine and comprising an ammonia cracking device according to a fifth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0012] According to one aspect, the present subject matter is directed to a system for generating power using a gas turbine, wherein the system comprises an ammonia- cracking device, to convert at least part of an NEE stream into EE and N2, to realize a gas NH3/H2/N2 mixture that allows operating the gas turbine in every condition.

[0013] In another aspect, the subject matter disclosed herein concerns a gas turbine auxiliary system for NH3 conditioning wherein a NH3 feed stream is splitted into two separate NH3 stream, a first NH3 stream is cracked into EE and N2 through a catalytic cracking reactor or a thermal cracking reactor to obtain a EE and N2 stream to be delivered to the gas turbine, and a second NH3 stream is directed to the gas turbine through a bypass line. In order to control the correct amount of ammonia, hydrogen and nitrogen delivered to the gas turbine, the system further comprises a plurality of flow valves, controlled by an auxiliary control unit, the flow valves including a gas flow valve arranged downstream the ammonia cracking reactor. Additionally or alternatively, the system can also comprise a gas NH3 bypass stream flow valve arranged along a gas NH3 feed line connected downstream the NH3 bypass stream line. In particular, downstream the cracking reactor, the EE and N2 stream can be mixed together with the second NH3 stream, to obtain a gas NH3/H2/N2 mixture with a controlled ratio of NH3 on one hand and EE and N2 on the other hand. Optionally, downstream the cracking reactor, N2 can be separated from EE gas in the EE and N2 stream, to obtain a gas NH3/H2/N2 mixture with a controlled ratio of NH3, EE and N2 and to additionally allow N2 to be used as a purge gas.

[0014] Reference now will be made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase “in one embodiment” or “in an embodiment” or “in some embodiments” in various places throughout the specification is not necessarily referring to the same embodiment s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] When introducing elements of various embodiments the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0016] Referring now to the drawings, Fig.1 shows a schematic of an exemplary power generating system comprising a gas turbine 100. The gas turbine 100 comprises a compressor, a combustion chamber and an expander. The gas turbine 100 is fed by a gas NH3/H2/N2 mixture stream and a gas NH3 stream. The gas NH3/H2/N2 mixture stream is directed to the primary stage of the gas turbine 100 through a gas turbine feed line 1 and the gas NH3 stream is directed to the secondary stage of the gas turbine 100 through a gas NH3 feed stream line 2. Moreover, a gas turbine auxiliary system for NH3 conditioning is arranged upstream the gas turbine 100, the gas turbine auxiliary system including a NH3 heater/vaporizer/pressurizer 200, to heat and then vaporize a liquid NH3 stream from a NH3 stream line 4, and a cracking reactor 300, which is connected to the NH3 heater/vaporizer/pressurizer through a NH3 heater/vaporizer/pressurizer gas outlet line 5 and a cracking reactor feed line 6. According to alternative exemplary embodiments, the NH3 heater/vaporizer/pressurizer is composed of shell-and-tube heat exchangers or plate-heat-exchangers. In some embodiments, a heat transfer fluid of the heater/vaporizer/pressurizer is the gas turbine exhaust gas or another intermediate fluid (like steam or thermal oil). According to an exemplary embodiment the heat exchanger is made in two stages, one to heat-up and vaporize liquid ammonia, the other to restore the initial pressure or eventually increase the ammonia gas pressure. In some embodiments, a storage tank for high pressure ammonia gas is also included into the heater/vaporizer/pressurizer system.

[0017] According to an exemplary embodiment shown in fig. 1, the NH3 cracking reactor 300 is a catalytic or thermal reactor, configured to process ammonia and dissociate it into at least its basic components, namely hydrogen and nitrogen, in presence of a catalyst or under temperature control, according to the reaction:

[0018] The mixture of hydrogen and nitrogen and eventually present unreacted ammonia resulting from the cracking reaction is then directed to the gas turbine 100 through a gas NH3/H2/N2 mixture stream outlet line 7, connected downstream to the gas turbine feed line 1.

[0019] A NH3 bypass stream is splitted from the gas NH3 stream form the heater/vaporizer/pressurizer through a gas NH3 bypass stream line 11, which is connected upstream to the heater/vaporizer/pressurizer gas outlet line 5 and which is connected downstream to the gas NH3 feed stream line 2 of the gas turbine 100, in particular to the secondary stage of the gas turbine 100.

[0020] The system allows the gas turbine control loop to control the ratio of NH3 to be combusted together with H2 and N2 from the cracking reactor, according to the gas turbine operative needs.

[0021] Exhaust gas from the gas turbine 100 is routed to an exhaust gas stream line 15, from which a portion of the exhaust gas stream is split through an exhaust gas heat recovery line 12, which is routed to the cracking reactor 300 and/or the NH3 heater/vaporizer/pressurizer 200. With reference to Fig. 1, the exhaust gas heat recovery line 12 is split into a first heat recovery sub-line 13, which is directed to the cracking reactor 300 and a second heat recovery sub-line 14, which is directed to the NH3 heater/vaporizer/pressurizer 200.

[0022] An emergency system (not shown) is arranged along the gas turbine feed line 1 and include a vent and emergency valves to prevent overpressure. [0023] The gas turbine auxiliary system for NH3 conditioning of Fig. 1 operates as follows. The system is started by liquid ammonia being heated/vaporized/pressurized inside the NH3 heater/vaporizer/pressurizer 200 and fed in gaseous state to the NH cracking reactor 300. Part of gaseous ammonia from the NH3 heater/vaporizer/pressurizer 200 is spilled to the gas NH3 bypass stream line Hand is routed to the gas turbine 100 through the gas NH3 feed stream line 2. Part of the heat produced by the gas turbine 100 is sent to the NH3 heater/vaporizer/pressurizer 200 and to the NH3 cracking reactor 300. Further liquid ammonia is heated, vaporized and pressurized in the vaporizer/pressurizer 200 and the NH3 cracking reactor 300 starts operations feeding gaseous mixture in the gas NH3/H2/N2 mixture stream outlet line 7. A storage drum (not shown) can optionally be arranged along the gas NH3/H2/N2 mixture stream outlet line 7. When pressure in the gas NH3/H2/N2 mixture stream outlet line 7 reaches a threshold value, start-up sequence of the gas turbine can begin. Gas turbine ignition is obtained using as fuel the streams fed through the gas turbine feed line 1 or the gas NH3 feed stream line 2, receiving a gas NH3 stream from the gas NH3 bypass stream line 11. If energy to start-up the NH3 heater/vaporizer/pressurizer 200 and the NH3 cracking reactor 300 is not available, a start-up fuel like natural-gas can be connected to the gas turbine feed line 1 or the gas NH3 feed stream line 2 and utilized for gas turbine ignition and ramp-up to gas turbine end-of-sequence or full-speed-no-load condition. Once the gas turbine is ignited, the exhaust gas heat starts to provide energy both to the NH3 heater/vaporizer/pressurizer 200 that heats, vaporizes and pressurizes liquid ammonia to gaseous state ammonia and to the NH3 cracking reactor 300 that cracks gaseous ammonia to a mixture of hydrogen, nitrogen and eventual unreacted ammonia. Once appropriate mixture is created, the flow of the gas NH3/H2/N2 mixture stream inside the gas turbine feed line 1 is controlled according to the gas turbine control schedules. During all the gas turbine sequences (ramp-up, load operations, normal shutdown) a gas turbine auxiliary control unit 37 manages the requirements of hydrogen, nitrogen and residual ammonia mixture composition of the gas turbine feed line 1, acting on the parameters of the NH3 cracking reactor 300 and managing the flow ratio between the gas turbine feed line 1 and the gas NH3 feed stream line 2. The parameters of the NH3 cracking reactor managed by the gas turbine auxiliary control unit 37 are strictly dependent from the NH3 cracking reactor technology. In some embodiments, the parameters of the NH3 cracking reactor comprise the temperature of the reacting ammonia gas at specific sections of the reactor (for example at the inlet section) and the NH3 cracking reactor recycle ratio. Emergency shutdown of the gas turbine 100 enables the immediate isolation of the gas turbine auxiliary system for NEE conditioning from the gas turbine 100 and the de-energization of the NH3 heater/va- porizer/pressurizer 200 and the NH3 cracking reactor 300 according to its specific safety requirements.

[0024] The operation of the gas turbine auxiliary system for NH3 conditioning of Fig. 1 is controlled through a plurality of control valves operated according to a control method that will be explained herein below. A gas flow valve 21 is arranged along the gas turbine feed line 1, downstream the NH3 cracking reactor 300, to control the flowing of the gas NH3/H2/N2 mixture stream inside the gas turbine feed line 1. A gas NH3 bypass stream flow valve 22 is arranged along the gas NH3 feed stream line 2, downstream the gas NH3 bypass stream line 11, to control the flow of gas NH3 bypass stream directed to the gas turbine 100, and conversely the flow of gas NH3 stream directed to the cracking reactor 300 through the cracking reactor feed line 6. Finally, a heat recovery flow valve 26 is arranged on the first heat recovery sub-line 13 in order to control the portion of the exhaust gas from the gas turbine 100 that is directed to the NH3 cracking reactor 300 and conversely the portion of exhaust gas directed to the NH3 heater/vaporizer/pressurizer 200. The gas flow valve 21, the gas NH3 bypass stream flow valve 22 and the heat recovery flow valve 26 can be electric-actuated valves, pneumatic-actuated valves or hydraulic-actuated valves.

[0025] With continuing reference to fig. 1, according to the block diagram of the control architecture of the power generating system shown in fig. 2, the flow valves 21 and 22 and the heat recovery flow valve 26 are operated as follows. A gas turbine control unit 30 such as, for example, a computer or programmable logic controller (PLC), receives the following input parameters: gas turbine parameters 31, combustion parameters 32 and NOx requirements 33. In particular, the gas turbine parameters 31 are dependent from the gas turbine technology. In some embodiments, the gas turbine parameters 31 comprise the gas turbine generated power, the gas turbine speed, the gas turbine exhaust gas temperature. The combustion parameters 32 are dependent from the combustion technology adopted by the gas turbine. In some embodiments, the combustion parameters 32 comprise fuel-to-air-ratio in specific zones of the combustor, distribution of the thermal load along the combustor and the NO_X and NH3 slip at the outlet of the combustor. NOx requirements 33 comprise NO_X exhaust gas emissions in the exhaust stream downstream the gas turbine. The total amount of gas fed to the gas turbine through the gas turbine feed line 1 (indicated with ml) and the gas NH3 feed stream line 2 (m2) are a function of the above gas turbine parameters: ml + m2 = f(GT param)

The volumetric composition of the gas NH3/H2/N2 mixture stream in the gas turbine feed line 1 (indicated by the reference number 34 in Fig. 2); the ratio 35 of the gas NH3 mass flow through the gas NH3 feed stream line 2 (m2) and the total mass flow (ml+m2) of the gas NH3/H2/N2 mixture stream through the gas turbine feed line 1 (ml) and the gas NH3 feed stream to the gas turbine through the gas NH3 feed stream line 2 (m2) are a function of the above combustion parameters and NOx requirements: XH = f(combustion parameters; NOx requirements) m2/(ml + m2) = f(combustion parameters; NOx requirements)

These parameters are the input(s) to the auxiliary control unit 37 such as, for example, a computer or programmable logic controller (PLC), configured to control the operation of the flow valves 21 and 22 and the heat recovery flow valve 26 according to the following relations. The operation Y21 of the gas flow valve 21 controlli ng the amount of gas NH3/H2/N2 mixture stream flowing inside the gas turbine feed line 1, is a function of the total amount of gas stream ml fed to the gas turbine through the gas turbine feed line 1 and the gas NH3 feed stream m2 fed to the gas turbine through the gas NH3 feed line 2:

Y21 = f(ml + m2)

The operation Y22 of the gas NH3 bypass stream valve 22 is a function of the ratio 35 of the gas NH3 mass flow m2 through the gas NH3 feed stream line 2 and the total mass flow of the gas NH3/H2/N2 mixture stream ml through the gas turbine feed line 1 and the gas NH3 feed stream m2 to the gas turbine through the gas NH3 feed stream line 2:

Y22 = f(m2/(ml + m2))

Finally, the operation of the heat recovery flow valve 26 is a function of the volumetric composition of the gas:

Y₂6 = f(xii)

[0026] The above described control method allows to change the composition of the fuel to the gas turbine and inject ammonia in any ratio according to any eventual combustor and gas turbine requirements (these requirements not being part of the present disclosure).

[0027] With continuing reference to Fig. 1 and Fig. 2, Fig.3 shows a schematic of an exemplary power generating system according to a second embodiment. The gas turbine 100 comprises a compressor, a combustion chamber and a turbine. The gas turbine 100 is fed by a gas NH3/H2/N2 mixture stream, a gas NH3 stream and a gas N2 stream. The gas NH3/H2/N2 mixture stream is directed to the primary stage of the gas turbine of the gas turbine 100 through a gas turbine feed line 1, the gas NH3 stream is directed to the secondary stage of the gas turbine of the gas turbine 100 through a gas NH3 feed stream line 2 and the gas N2 stream is directed to the secondary stage of the gas turbine of the gas turbine 100 through a gas N2 feed stream line 3. Moreover, a gas turbine auxiliary system for NH3 conditioning is arranged upstream the gas turbine 100, the gas turbine auxiliary system including a NH3 heater/vaporizer/pressurizer 200, to heat and then vaporize a liquid NH3 stream from a NH3 stream line 4, and a cracking reactor 300, which is connected to the NH3 heater/vaporizer/pressurizer through a NH3 heater/vaporizer/pressurizer gas outlet line 5 and a cracking reactor feed line 6.

[0028] According to this embodiment, the mixture of hydrogen and nitrogen and unreacted ammonia resulting from the cracking reaction is treated to separate a gas NH3/H2/N2 mixture stream and a gas N2 stream. The gas NH3/H2/N2 mixture stream from the cracking reactor 300 is directed to the gas turbine 100 through a gas NH3/H2/N2 mixture stream outlet line 7, connected downstream to the gas turbine feed line 1.

[0029] The separation of nitrogen can be obtained through different technologies. According to an exemplary embodiment, the NH3 cracking reactor 300 is a membrane reactor, operating as follows. A membrane separates the reactor into two separate sections. A first section is directly connected to the cracking reactor feed line 6. Ammonia fed to the membrane reactor is reacted inside the first section. A fraction of nitrogen resulting from the cracking reaction permeates the membrane and passes to a second section of the membrane reactor, separating from hydrogen, unreacted ammonia and a remaining fracti on of nitrogen, which remain inside the first secti on of the membrane reactor. [0030] The gas N2 stream from the cracking reactor 300 is directed to the gas turbine 100 through a gas N2 stream outlet line 8, connected downstream to the gas N2 feed stream line 3. A fraction of the gas N2 stream from the cracking reactor 300 can be split and returned to the gas NH3/H2/N2 mixture stream outlet line 7 through a gas N2 bypass line 9, to control the composition of the NH3/H2/N2 mixture stream directed to the gas turbine 100 through the gas turbine feed line 1.

[0031] A NH3 bypass stream is splitted (split off) from the gas NH3 stream form the heater/vaporizer/pressurizer through a gas NH3 bypass stream line 11, which is connected upstream to the heater/vaporizer/pressurizer gas outlet line 5 and which is connected downstream to the gas NH3 feed stream line 2 of the gas turbine 100, in particular to the secondary stage of the gas turbine of the gas turbine 100.

[0032] The composition of the NH3/H2/N2 mixture stream directed to the gas turbine 100 through the gas turbine feed line 1 is also controlled by mixing the gas NH3/H2/N2 mixture stream with ammonia. To this end a gas NH3 bypass split stream is withdrawn from the gas NH3 bypass stream through a gas NH bypass split stream line 10, which is connected upstream to the gas NH3 bypass stream line 11 and downstream to the gas NH3/H2/N2 mixture stream outlet line 7.

[0033] The system allows the gas turbine control loop to control the ratio of NH3 to be combusted together with H2 and N2 from the cracking reactor, according to the gas turbine operative needs.

[0034] Exhaust gas from the gas turbine 100 is routed to an exhaust gas stream line 15, from which a portion of the exhaust gas stream is split through an exhaust gas heat recovery line 12, which is routed to the cracking reactor 300 and/or the NH3 heater/vaporizer/pressurizer 200. With reference to Fig. 3, the exhaust gas heat recovery line 12 is split into a first heat recovery sub-line 13, which is directed to the cracking reactor 300 and a second heat recovery sub-line 14, which is directed to the NH3 heater/vaporizer/pressurizer 200.

[0035] An emergency system (not shown) is arranged along the gas turbine feed line 1 and include a vent and emergency valves to prevent overpressure.

[0036] The gas turbine auxiliary system for NH3 conditioning of Fig. 3 operates as follows. The system is started by liquid ammonia being heated/vaporized/pressurized inside the NH3 heater/vaporizer/pressurizer 200 and fed in gaseous state to the NH3 cracking reactor 300. Part of gaseous ammonia from the NH3 heater/vaporizer/pressurizer 200 is spilled to the gas NH3 bypass stream line Hand is routed to the gas turbine 100 through the gas NH3 feed stream line 2. Part of the heat produced by the gas turbine 100 is sent to the NH3 heater/vaporizer/pressurizer 200 and to the NH3 cracking reactor 300. Further liquid ammonia is heated, vaporized and pressurized in the vaporizer/pressurizer 200 and the NH3 cracking reactor 300 starts operations feeding gaseous mixture in the gas NH3/H2/N2 mixture stream outlet line 7. A storage drum (not shown) can optionally be arranged along the gas NH3/H2/N2 mixture stream outlet line 7. When pressure in the gas NH3/H2/N2 mixture stream outlet line 7 reaches a threshold value, start-up sequence of the gas turbine can begin. Gas turbine ignition is obtained using as fuel the streams fed through the gas turbine feed line 1 or the gas NH3 feed stream line 2, receiving a gas NH3 stream from the gas NH3 bypass stream line 11. If energy to start-up the NH3 heater/vaporizer/pressurizer 200 and the NH3 cracking reactor 300 is not available, a start-up fuel like natural-gas can be connected to the gas turbine feed line 1 or the gas NH3 feed stream line 2 and utilized for gas turbine ignition and ramp-up to gas turbine end-of-sequence or full-speed-no-load condition. Once the gas turbine is ignited, the exhaust gas heat starts to provide energy both to the NH3 heater/vaporizer/pressurizer 200 that heats, vaporizes and pressurizes liquid ammonia to gaseous state ammonia and to the NH3 cracking reactor 300 that cracks gaseous ammonia to a mixture of hydrogen, nitrogen and unreacted ammonia. Once appropriate mixture is created, the flow of the gas NH3/H2/N2 mixture stream inside the gas turbine feed line 1 is controlled according to the gas turbine control schedules. During all the gas turbine sequences (ramp-up, load operations, normal shutdown) a gas turbine control system manages the requirements of hydrogen, nitrogen and residual ammonia mixture composition of the gas turbine feed line 1, acting on the parameters of the NH3 cracking reactor 300 and managing the flow ratio between the gas turbine feed line 1 and the gas NH3 feed stream line 2. Emergency shutdown of the gas turbine enables the immediate isolation of the gas turbine auxiliary system for NH3 conditioning from the gas turbine and the de-energization of the NH3 heater/vaporizer/pressurizer 200 and the NH3 cracking reactor 300 according to its specific safety requirements. The NH3 cracking reactor 300 also separates nitrogen from the gas mixture of hydrogen, nitrogen and unreacted ammonia and therefore provides a stream of N2 in the gas N2 stream outlet line 8, which can be used for different applications, like N2 storage or purging services for the gas turbine.

[0037] The operation of the gas turbine auxiliary system for NH3 conditioning of Fig. 3 is controlled through a plurality of control valves operated according to a control method that will be explained herein below. A gas flow valve 21, namely a valve 21, is arranged along the gas turbine feed line 1, to control the flowing of the gas NH3/H2/N2 mixture stream inside the gas turbine feed line 1. A gas NH3 bypass stream flow valve 22 is arranged along the gas NH3 bypass stream line 11 to control the flow of gas NH3 bypass stream directed to the gas turbine through the gas NH3 feed stream line 2, and conversely the flow of gas NH3 stream directed to the cracking reactor 300 through the cracking reactor feed line 6. A gas NH3 bypass split stream flow valve 23 is arranged along the gas NH3 bypass split stream line 10 to control the amount of gas NH3 bypass stream routed to the gas NH3/H2/N2 mixture stream outlet line 7 in order to control the composition of the NH3/H2/N2 mixture stream directed to the gas turbine 100 through the gas turbine feed line 1. A gas N2 bypass stream flow valve 24 is arranged along the gas N2 bypass line 9 to control the flow of nitrogen of the gas N2 stream outlet line 8 from the NH3 cracking reactor 300 used to mix with the gas NH3/H2/N2 mixture stream directed to the gas turbine 100 through the gas turbine feed line 1. Additionally a gas turbine N2 feed stream flow valve 25 is arranged along the gas N2 feed stream line 3, to control the flow of nitrogen of the gas N2 stream outlet line 8 from the NH3 cracking reactor 300 directed to the gas turbine 100. Finally, a heat recovery flow valve 26 is arranged on the first heat recovery sub-line 13 in order to control the portion of the heat recovery flow of the exhaust gas from the gas turbine 100 that is directed to the NH3 cracking reactor 300 and conversely the portion of heat recovery flow directed to the NH3 heater/vaporizer/pressurizer 200. The gas flow valve 21, the gas NH3 bypass stream flow valve 22, the gas NH3 bypass split stream flow valve 23, the gas N2 bypass stream flow valve 24, the gas turbine N2 feed stream flow valve 25 and the heat recovery flow valve 26 can be electric-actuated valves, pneumatic-actuated valves or hydraulic-actuated valves.

[0038] With continuing reference to Fig. 3, according to the block diagram of the control architecture of the power generating system shown in Fig. 4, the flow valves 21-25 and the heat recovery flow valve 26 are operated as follows. Input parameters to the gas turbine control unit 30 are the gas turbine parameters 31, the combustion parameters 32 and the NOx requirements 33. The total amount of gas fed to the gas turbine as the sum of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line 1, the gas NH3 feed stream line 2 and the gas N2 feed stream (m3) through the gas N2 feed stream line 3 is a function of the gas turbine parameters: ml + m2 + m3 = f(GT param)

The volumetric composition of the gas NH3/H2/N2 mixture stream in the gas turbine feed line 1 (indicated by the reference number 34 in Fig. 2); the ratio 35 of the gas NH3 mass flow m2 through the gas NH3 feed stream line 2 and the total mass flow of the gas NH3/H2/N2 mixture stream ml through the gas turbine feed line 1 and the gas NH3 feed stream m2 to the gas turbine through the gas NH3 feed stream line 2; and the ratio 36 of the gas N2 mass flow through the gas N2 feed stream line 3 and the total mass flow of the gas NH3/H2/N2 mixture stream through the gas turbine feed line 1 and the gas NH3 feed stream to the gas turbine through the gas NH3 feed stream line 2 are a function of the combustion parameters and NOx requirements:

Xu = flcombustion parameters; NOx requirements) m2/(ml + m2) = f(combustion parameters; NOx requirements) m3/(ml + m2) = f(combustion parameters; NOx requirements)

These parameters are the input of an auxiliary control unit 37, controlling the operation of the flow valves 21-25 and the heat recovery flow valve 26 according to the following relations. The operation Y21 of the gas flow valve 21 controlling the amount of gas NH3/H2/N2 mixture stream flowing inside the gas turbine feed line 1, is a function of the total amount of gas fed to the gas turbine through the gas turbine feed line 1 (ml), the gas NH3 feed stream line 2 (m2) and the gas N2 feed stream line 3 (m3):

Y21 = f(ml + m2 + m3)

The operation Y22 of the gas NH3 bypass stream valve 22 is a function of the ratio 35 of the gas NH3 mass flow through the gas NH3 feed stream line 2 and the total mass flow of the gas NH3/H2/N2 mixture stream through the gas turbine feed line 1 and the gas NH3 feed stream to the gas turbine through the gas NH3 feed stream line 2:

Y22 = f(m2/(ml + m2))

The operation Y23 of the gas NH3 bypass split stream valve 23 is a function of the volumetric composition of the gas NH3/H2/N2 mixture stream in the gas turbine feed line 1 :

Y23 = f(xii) Also the operation Y24 of the gas N2 bypass stream valve 24 is a function of the volumetric composition of the gas NH3/H2/N2 mixture stream in the gas turbine feed line 1 :

Y₂4 = f(xii)

The operation Y25 of the gas turbine N2 feed stream valve 25 is a function of the ratio 36 of the gas N2 mass flow m3 through the gas N2 feed stream line 3 and the total m ass flow of the gas NH3/H2/N2 mixture stream through the gas turbine feed line 1 and the gas NH3 feed stream to the gas turbine through the gas NH3 feed stream line 2:

Y25 = f(m3/(ml + m2))

Finally, the operation of the heat recovery flow valve 26 is a function of the volumetric composition of the gas NH3/H2/N2 mixture stream in the gas turbine feed line 1 :

Y₂6 = f(xii)

[0039] The above described control method allows to change the composition of the fuel to the gas turbine and inject ammonia and nitrogen in any ratio according to any eventual combustor and gas turbine requirements (these requirements not being part of the present disclosure).

[0040] For example: if the combustor requires an hydrogen-rich fuel but a consistent inert fluid (N2) to reduce flame temperatures and augment power of the gas turbine, then Case 1 of the following Table 1 is applicable. If the combustor requires a hydrogen-rich fuel but a consistent separate ammonia injection, to optimize NOx emission, Case 3 of Table 1 is applicable. In case the combustor does not require high amount of hydrogen, high separate ammonia and high separate nitrogen, Case 2 of Table 1 is applicable.

Table 1

[0041] With continuing reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4, Fig. 5 illustrates a third embodiment of a power generating system using a gas turbine and comprising an ammonia cracking device. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Fig. 1, Fig. 2, Fig. 3 and Fig. 4 and described above, and which will not be described again.

[0042] The embodiment shown in Fig. 5 differs from the embodiment of Fig. 3 in that at least part of the gas N2 stream from the cracking reactor 300 is not directed to the gas turbine 100, but is collected and used for different purposes. According to this embodiment, the gas N2 stream outlet line 8 is connected downstream to a gas N2 withdrawal line 3’. A stream valve 25’ is arranged along the gas N2 withdrawal line 3’, to control the flow of nitrogen of the gas N2 stream outlet line 8 from the NH3 cracking reactor 300 directed to external uses. The control method for this embodiment differs from that described with reference to Fig. 3 and Fig. 4 in that the operation Y25 of the stream valve 25’ is a function of requirements that do not form an object of the present invention:

Y25’ = f(other requirements)

[0043] With continuing reference to Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, Fig. 6 illustrates a fourth embodiment of a power generating system using a gas turbine and comprising an ammonia cracking device. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5 and described above, and which will not be described again.

[0044] The embodiment shown in Fig. 6 differs from the embodiments of Fig. 3 and Fig. 5 in that the injection points of the gas turbine feed line 1 and the gas NH3 feed stream line 2 are swapped. Swapping the injection points can be needed to take into account different combustion technologies that could be applied into the gas turbine with different flame evolution along the flow path inside the combustor. In particular, according to this embodiment, the gas turbine feed line 1 is directed to the secondary stage of the gas turbine of the gas turbine 100 and the gas NH3 feed stream line 2 is directed to the primary stage of the gas turbine of the gas turbine 100. The control method for this embodiment is the same as that described with reference to Fig. 3 and Fig. 4. [0045] Moreover, with continuing reference to Figs. 1-6, Fig. 7 illustrates a fifth embodiment of a power generating system using a gas turbine and comprising an ammonia cracking device. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs. 1-6 and described above, and which will not be described again.

[0046] The embodiment shown in Fig. 7 differs from the embodiments of Figs. 3-6 in that both at least part of the gas N2 stream from the cracking reactor 300 is not directed to the gas turbine 100, but is collected and used for different purposes, and the injection points of the gas turbine feed line 1 and the gas NH3 feed stream line 2 are swapped. In particular, according to this embodiment, the gas turbine feed line 1 is directed to the secondary stage of the gas turbine of the gas turbine 100 and the gas NH3 feed stream line 2 is directed to the primary stage of the gas turbine of the gas turbine 100. Moreover, the gas N2 stream outlet line 8 is connected downstream to a gas N2 withdrawal line 3’. The control method for this embodiment is the same as that described with reference to Fig. 5.

[0047] Finally, with continuing reference to Figs. 1-7, Fig. 8 illustrates a sixth embodiment of a power generating system using a gas turbine and comprising an ammonia cracking device. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs. 1-7 and described above, and which will not be described again.

[0048] The embodiment shown in Fig. 8 differs from the embodiments of Figs. 3-7 in that at least part of the gas N2 stream from the cracking reactor 300 is not directed to the gas turbine 100, but is routed to the gas NH3 feed stream line 2. In particular, according to this embodiment, at least part of the gas N2 stream from the cracking reactor 300 is used to purge the gas NH3 feed stream line 2, when needed.

[0049] While aspects of the invention have been described in terms of various specific embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing from the spirt and scope of the claims. In addition, unless specified otherwise herein, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.

Claims

1. A power generating system comprising a gas turbine (100) and a gas turbine auxiliary system for NH3 conditioning, wherein

- the gas turbine auxiliary system for NH3 conditioning is configured to process an ammonia input stream and obtain a decomposition gas comprising at least hydrogen and nitrogen, preferably a gas NH3/H2/N2 mixture,

- the gas turbine auxiliary system for NH3 conditioning comprising an ammonia cracking reactor (300),

- the ammonia input stream being split into a cracking reactor feed line (6) and a NH3 bypass line (11),

- the ammonia cracking reactor (300) being configured to decompose ammonia into a gas mixture of hydrogen and nitrogen or hydrogen, nitrogen and residual ammonia, a cracking reactor gas mixture outlet line (7) being connected to the gas turbine (100),

- the NH3 bypass stream line (11) being connected to the gas turbine (100) through a gas NH3 feed stream line (2),

- the system comprising a gas turbine feed line (1) and a plurality of flow valves (21, 22, 23, 24, 25), which are controlled by an auxiliary control unit; and wherein

- the plurality of flow valves (21, 22, 23, 24, 25) comprises a gas flow valve (21) arranged along the gas turbine feed line (1), downstream the ammonia cracking reactor (300), and/or a gas NH3 bypass stream flow valve (22) arranged along the gas NH3 feed line (2) connected downstream the NH3 bypass stream line (H).

2. The power generating system of claim 1, wherein the ammonia cracking reactor (300) is configured to separate a nitrogen stream and a gas mixture of hydrogen and residual nitrogen or hydrogen, residual nitrogen and residual ammonia.

3. The power generating system of claim 2, wherein nitrogen separated from the gas mixture of hydrogen and nitrogen or the gas mixture of hydrogen, nitrogen and residual ammonia is withdrawn from the ammonia cracking reactor (300) through a nitrogen stream line (8), the nitrogen stream line (8) being connected to the gas turbine feed line (1) through a gas nitrogen feed line (9) upstream the gas turbine (100) and/or to the gas turbine (100) through a gas nitrogen feed line (3) and/or to a gas N2 withdrawal line 3 ’ .

4. The power generating system of any of the previous claims, also comprising a gas NH3 bypass split stream line (10), which is connected upstream to the NH3 bypass stream line (11) and downstream to the cracking reactor gas mixture outlet line (7), upstream the gas turbine (100), to form a gas turbine feed line (1).

5. The power generating system of any of the previous claims, wherein the NH3 bypass stream is injected through the gas NH3 feed line (2) into the primary or alternatively the secondary stage of the gas turbine (100).

6. The power generating system of any of claims 1-5, also comprising a NH3 heater/vaporizer/pressurizer (200) configured to heat/vaporize/pressurize an at least partially liquid ammonia input stream.

7. The power generating system of any of the claims 1-5, also comprising a NH3 pressurizer configured to pressurize a gas ammonia input stream.

8. The power generating system of claim 4, wherein the plurality of flow valves (21, 22, 23, 24, 25) also comprises a gas NH3 bypass split stream flow valve (23) arranged along the gas NH3 bypass split stream line (10).

9. The power generating system of claim 2, wherein the plurality of flow valves (21, 22, 23, 24, 25) also comprises a gas N2 bypass stream flow valve (24) arranged along the gas N2 bypass line (9) and/or a gas turbine N2 feed stream flow valve (25) is arranged along the gas N2 feed stream line (3).

10. The power generating system of any of the previous claims, also comprising a heat recovery system configured to recover at least part of the heat of an exhaust gas stream from the gas turbine (100), the heat recovery system comprising a first heat recovery sub-line (13), configured to convey a first portion of the exhaust gas stream to the cracking reactor (300) and/or a second heat recovery sub-line (14), configured to convey a second portion of the exhaust gas stream to the NH3 heater/vapor- izer/pressurizer (200).

11. The power generating system of claim 10, also comprising at least one heat recovery flow valve (26).

12. The power generating system of claim 11, wherein the at least one heat recovery flow valve (26) is arranged on the first heat recovery sub-line (13) or on the second heat recovery sub-line (14).

13. A method for controlling operation of the power generating system of previous claims 1-12, the method comprising the following steps: determining the total amount (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) fed to the gas turbine through the gas turbine feed line (1) and the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) as a function of the gas turbine parameters; determining (34) the volumetric composition (xn) of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1) and the ratio (35) of the gas NH3 mass flow (m2) through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) to the gas turbine through the gas NH3 feed stream line (2) as a function of the combustion parameters (32) and NOx requirements (33); determining the operation (Y21) of the gas flow valve (21) controlling the amount of gas NH3/H2/N2 mixture stream flowing inside the gas turbine feed line (1) as a function of the total amount (ml + m2) of gas stream (ml) fed to the gas turbine through the gas turbine feed line (1) and the gas NH3 feed stream (m2) fed to the gas turbine through the gas NH3 feed line (2); and

- determining the operation (Y22) of the gas NH3 bypass stream valve (22) as a function of the ratio (35) of the gas NH3 mass flow (m2)+ through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) to the gas turbine through the gas NH3 feed stream line (2).

14. The method for controlling operation of the power generating system of claim 13, the method also comprising the following step:

- determining the operation (Y26) of the heat recovery flow valve (26) as a function of the volumetric composition (xn) of the gas.

15. A method for controlling operation of the power generating system of previous claims 1-12, the method comprising the following steps: determining the total amount (ml + m2 + m3) of gas fed to the gas turbine (100) by the NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1), the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) and the gas N2 feed stream (m3) through the gas N2 feed stream line (3) as a function of the gas turbine parameters;

- determining (34) the volumetric composition (xn) of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1), the ratio (35) of the gas NH3 mass flow (m2) through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) and the ratio (36) of the gas N2 mass flow (m3) through the gas N2 feed stream line (3) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) as a function of the combustion parameters and NOx requirements;

- determining the operation (Y21) of the gas flow valve (21) controlling the amount of gas NH3/H2/N2 mixture stream flowing inside the gas turbine feed line (1) as a function of the total amount (ml + m2 + m3) of gas stream fed to the gas turbine by the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1), the gas NH3 feed stream (m2) fed to the gas turbine through the gas NH3 feed line (2) and the gas N2 feed stream (m3) through the gas N2 feed stream line (3);

- determining the operation (Y22) of the gas NH3 bypass stream valve (22) as a function of the ratio (35) of the gas NH3 mass flow (m2) through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) to the gas turbine through the gas NH3 feed stream line (2); - determining the operation (Y24) of the gas N2 bypass stream valve (24) as a function of the volumetric composition xn of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1);

- determining the operation (Y25) of the gas turbine N2 feed stream valve (25) as a function of the ratio (36) of the gas N2 mass flow (m3) through the gas N2 feed stream line (3) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) to the gas turbine through the gas NH3 feed stream line (2).

16. The method for controlling operation of the power generating system of claim 15, the method also comprising the following step:

- determining the operation (Y26) of the heat recovery flow valve (26) as a function of the volumetric composition of the gas.

17. A method for controlling operation of the power generating system of previous claims 1-12, the method comprising the following steps:

- determining the total amount (ml + m2 + m3) of gas fed to the gas turbine (100) by the NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1), the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) and the gas N2 feed stream (m3) through the gas N2 feed stream line (3) as a function of the gas turbine parameters;

- determining the volumetric composition (34) of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1), the ratio (35) of the gas NH3 mass flow (m2) through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) and the ratio (36) of the gas N2 mass flow (m3) through the gas N2 feed stream line (3) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) through the gas NH3 feed stream line (2) as a function of the combustion parameters and NOx requirements;

- determining the operation (Y22) of the gas NH3 bypass stream valve (22) as a function of the ratio (35) of the gas NH3 mass flow (m2) through the gas NH3 feed stream line (2) and the total mass flow (ml + m2) of the gas NH3/H2/N2 mixture stream (ml) through the gas turbine feed line (1) and the gas NH3 feed stream (m2) to the gas turbine through the gas NH3 feed stream line (2);

- determining the operation (Y23) of the gas NH3 bypass split stream valve (23) as a function of the volumetric composition xn of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1);

- determining the operation (Y24) of the gas N2 bypass stream valve (24) as a function of the volumetric composition xu of the gas NH3/H2/N2 mixture stream in the gas turbine feed line (1);

18. The method for controlling operation of the power generating system of claim 17, the method also comprising the following step: determining the operation (Y26) of the heat recovery flow valve (26) as a function of the volumetric composition of the gas.