Process for generating power in gas turbine

Abstract

A process for providing thermal energy for an ammonia cracking reactor. The invention includes recovering an oxygen-containing off-gas from a hydrogen-fueled gas turbine and supplying at least a portion of the off-gas to a fuel combustion zone to produce thermal energy for an ammonia cracking reactor. The invention can be used in chemical production facilities, such as ammonia production facilities.

Description

Technical Field

[0001] The present invention relates to a process for ammonia cracking. More specifically, the present invention relates to a process for providing heat to an ammonia cracking reactor. The present invention also relates to a method for retrofitting an ammonia plant using the process of the present invention. Background Art

[0002] There is growing interest in using carbon-free fuels to power gas turbine systems to generate carbon-free electricity. Among such carbon-free fuels, ammonia is of interest for carbon-free power generation in ammonia production facilities, where an ample supply of ammonia exists. However, the development of gas turbine systems fueled by ammonia is in its infancy. Many commercially available gas turbines are not suitable for use with ammonia fuel.

[0003] A potential solution for using ammonia as a direct fuel is to crack the ammonia to form a mixture of hydrogen and nitrogen, allowing the combustion of hydrogen to drive the gas turbine.

[0004] For many years, the splitting of ammonia into hydrogen and nitrogen has been used to provide hydrogen for catalyst activation in ammonia plants. The reaction can be depicted as follows:

[0005]

[0006] The ammonia cracking reaction is endothermic and can be efficiently achieved by passing ammonia over a suitable catalyst in externally heated catalyst-containing reaction tubes arranged in a furnace. Such furnaces are known, for example, for steam reforming of natural gas or naphtha feedstocks.

[0007] It is known to burn a hydrogen stream in a gas turbine. US2022162999 and US2022162989 disclose processes comprising a gas turbine driven by the combustion of a stream containing hydrogen and a compressed air stream. The hydrogen-containing stream is produced in an ammonia cracker fed with an ammonia stream. The gas turbine is used to generate electrical and mechanical energy. The heat generated by the combustion of the hydrogen-containing stream is supplied directly to the cracker or used to preheat the ammonia stream upstream of the cracker through a heat exchanger.

[0008] There remains a need to improve the efficiency of gas turbines driven by the combustion of carbon-free fuels, particularly ammonia-derived fuels. Summary of the invention

[0009] The present invention seeks to improve the energy efficiency of a gas turbine system driven by the combustion of a carbon-free fuel derived from the catalytic cracking of ammonia.

[0010] Thus, in a first aspect of the invention there is provided a process for generating electricity using a gas turbine fuelled by a carbon-free fuel derived from catalytic cracking of ammonia, the process comprising:

[0011] supplying an ammonia stream to an ammonia cracking reactor;

[0012] cracking ammonia in the ammonia stream in the ammonia cracking reactor to produce a hydrogen-containing stream;

[0013] combining the hydrogen-containing stream with an oxygen-containing feed and combusting the hydrogen-containing stream with the oxygen-containing feed to produce a combusted gas stream;

[0014] using the combustion gas stream to drive a gas turbine and produce an oxygen-containing exhaust gas stream;

[0015] supplying at least a portion of the oxygen-containing waste gas stream to a fuel combustion zone; and

[0016] A fuel stream and the oxygen-containing exhaust gas stream are combusted in the fuel combustion zone to generate heat energy for the ammonia cracking reactor.

[0017] It has been surprisingly found that the exhaust gas stream from the gas turbine contains sufficient oxygen for combustion of the fuel stream in the fuel combustion zone. Furthermore, the oxygen-containing exhaust gas leaves the gas turbine at an elevated temperature and therefore requires little or no preheating prior to combustion with the fuel stream. In the process of the present invention, by supplying heat energy generated by the combustion of the fuel stream and the oxygen-containing exhaust gas to the ammonia cracking reactor, it has been surprisingly found that unexpected energy savings can be achieved.

[0018] Another advantage of the process of the invention is that the cost of fixed equipment can also be reduced. For example, because at least a portion of the oxygen-containing waste gas is used in the combustion of the fuel stream, less energy needs to be recovered from the remaining oxygen-containing waste gas that is not used in the combustion of the fuel stream. This means that smaller and therefore cheaper equipment (e.g. heat recovery equipment, such as a heat recovery steam generator) can be specified.

[0019] The gas turbine according to the present invention may be referred to as an integrated gas turbine because the oxygen-containing exhaust gas stream it produces is recovered and supplied to the fuel combustion zone. In contrast, reference to a non-integrated gas turbine includes processes in which the oxygen-containing exhaust gas stream produced from the gas turbine is not used for combustion.

[0020] The process of the present invention is particularly suitable for implementation in or near an ammonia production or storage facility, where a supply of ammonia can provide an input to an ammonia cracking reactor to produce hydrogen in a hydrogen-containing stream, and also be combusted as a fuel stream with an oxygen-containing exhaust gas stream to provide heat to the ammonia cracking reactor. However, the process of the present invention is not limited to implementation in an ammonia production facility, and can be used in any suitable setting where a supply of ammonia is available.

[0021] In another aspect of the invention there is provided a method of improving an ammonia production facility by implementing the process of the first aspect of the invention in the ammonia production facility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A block flow diagram of a comparative process including a non-integrated gas turbine is shown.

[0023] Figure 2 A block flow diagram of the process of the present invention including an integrated gas turbine is shown. DETAILED DESCRIPTION

[0024] The preferred and / or optional features of the present invention will now be described. Unless the context otherwise requires, any aspect of the present invention may be combined with any other aspect of the present invention. Unless the context otherwise requires, any preferred and / or optional features of any aspect may be combined with any aspect of the present invention individually or in combination.

[0025] The process of the present invention comprises supplying an ammonia stream to an ammonia cracking reactor.

[0026] The ammonia stream may be derived from any source. In a preferred process of the invention, the ammonia stream is produced by a catalytic combination of hydrogen and nitrogen, for example, the ammonia stream may be produced by a Haber-Bosch ammonia synthesis process. In a preferred process of the invention, the ammonia stream may be produced in an ammonia production facility upstream of the ammonia cracking reactor. Alternatively, the ammonia stream may be provided by an ammonia storage facility or an ammonia pipeline.

[0027] In a preferred process of the present invention, the ammonia stream may be preheated before being supplied to the ammonia cracking reactor. Therefore, the process of the present invention may include a step of preheating the ammonia stream. The ammonia stream may be preheated to a temperature greater than 350°C, greater than 400°C, greater than 450°C, greater than 500°C or greater than 550°C. The ammonia stream may be preheated to a temperature less than 1000°C, less than 950°C, less than 850°C, less than 750°C or less than 700°C. The ammonia stream may be preheated to a temperature of 350°C to 1000°C, 400°C to 950°C, 450°C to 850°C or 500°C to 750°C (such as 550°C to 700°C).

[0028] Suitable ammonia cracking reactors are known and may include a box furnace providing a radiant section including one or more burners to which a fuel stream and an oxygen feed gas (such as air) are fed. The radiant section includes one or more catalyst-containing tubes through which the ammonia stream passes. Combustion of the fuel stream in the one or more burners produces radiant heat for heating one or more reaction tubes containing the ammonia cracking catalyst. There may be dozens or hundreds of tubes in the radiant section. If desired, combustion gases may be used downstream of the radiant section to preheat one or more feed streams in the convection section. Reactors including a radiant section containing reaction tubes and convection for preheating the feed are known in steam methane reforming and may be applied to the present invention.

[0029] An alternative ammonia cracking reactor may be used, for example one in which the combustion of the fuel in the fuel combustion zone is separated from the reactor comprising tubes containing the catalyst. Such a reactor is a compact reformer commercially available from Johnson Matthey Davy Technologies Limited.

[0030] The catalyst may be any ammonia cracking catalyst. Nickel catalysts and ruthenium catalysts may be used. A preferred catalyst is a nickel catalyst. The catalyst may comprise 3 to 30 wt % nickel, preferably 8 to 20 wt % nickel, expressed as NiO, on a suitable refractory support such as alumina or a metal aluminate. The catalyst may be in the form of a granular unit which may include one or more through holes, or may be a washcoat on a structured metal or ceramic catalyst. A particularly preferred catalyst is KATALCO available from Johnson Matthey PLC. RTM 27-2, which comprises 12% nickel expressed as NiO on cylindrical particles formed from a high surface area alumina support.

[0031] The process of the present invention comprises the step of cracking ammonia in an ammonia stream in an ammonia cracking reactor to produce a hydrogen-containing stream.

[0032] The temperature of the ammonia stream at the inlet of the ammonia cracking reactor may be in the range of 350° C. to 1000° C., 400° C. to 950° C., 450° C. to 850° C., or 500° C. to 750° C., such as 550° C. to 700° C. The temperature of the hydrogen-containing stream leaving the ammonia cracking reactor will affect the equilibrium position of the cracking reaction and may be in the range of 500° C. to 950° C. When a nickel catalyst is used in the ammonia cracking reactor, the temperature of the hydrogen-containing stream leaving the ammonia cracking reactor may preferably be above about 700° C.

[0033] The inlet pressure to the ammonia cracking reactor will be set by the flowsheet design and may be in the range of 1 to 100 bar absolute, preferably 10 to 90 bar absolute, such as 31 to 51 bar absolute.

[0034] The ammonia cracking reaction produces a hydrogen-containing stream which also contains nitrogen and may contain residual ammonia.

[0035] The hydrogen-containing stream may contain 40 mol% or more hydrogen, 50 mol% or more hydrogen, or 60 mol% or more hydrogen. The hydrogen-containing stream may contain 75 mol% or less hydrogen, 70 mol% or less hydrogen, or 65 mol% or less hydrogen. For example, the hydrogen-containing stream may contain 40 mol% to 75 mol% hydrogen, 50 mol% to 70 mol% hydrogen, or 60 mol% to 65 mol% hydrogen.

[0036] The hydrogen-containing stream may optionally be fed to a purification unit, such as a pressure swing adsorption unit, to increase the hydrogen content by separating it from other components. Thus, the process of the present invention may include the steps of feeding a hydrogen-containing stream to a purification unit and increasing the hydrogen content of the hydrogen-containing stream to produce a hydrogen-rich stream and a tail gas.

[0037] The hydrogen-rich stream may contain 50 mol% or more hydrogen, 60 mol% or more hydrogen, or 75 mol% or more hydrogen. The hydrogen-rich stream may contain 100 mol% or less hydrogen, 90 mol% or less hydrogen, or 80 mol% or less hydrogen. For example, the hydrogen-rich stream may contain 50 mol% to 100 mol% hydrogen, 60 mol% to 90 mol% hydrogen, or 70 mol% to 80 mol% hydrogen, such as about 75 mol% hydrogen.

[0038] The tail gas may contain nitrogen and small amounts of ammonia and hydrogen. For example, the tail gas may contain nitrogen and 1 mol% to 10 mol% ammonia (e.g., about 5 mol% or less ammonia) and 2 mol% to 40 mol% hydrogen (e.g., 15 mol% to 25 mol% hydrogen).

[0039] As used herein, the term "hydrogen-containing stream" may be used to refer to a hydrogen-containing stream or a hydrogen-rich stream.

[0040] The hydrogen-containing stream may be fed to a steam generation unit and / or a heat recovery zone prior to combustion with the oxygen-containing feed.As will be appreciated by those skilled in the art, the steam generation unit and / or the heat recovery zone may be used to recover low-grade or medium-grade heat.

[0041] It is desirable to separate residual ammonia from the hydrogen-containing stream prior to combustion of the hydrogen-containing stream with the oxygen-containing feed. Removal of ammonia can be accomplished by scrubbing with water, for example using conventional scrubbing equipment.

[0042] The process of the present invention comprises the steps of combining a hydrogen-containing stream with an oxygen-containing feed and combusting the hydrogen-containing stream and the oxygen-containing feed to produce a combusted gas stream.

[0043] The oxygen-containing feed may be air, oxygen or oxygen-enriched air. In a preferred process of the present invention, the oxygen-containing feed is a compressed oxygen-containing feed, such as compressed air, compressed oxygen or compressed oxygen-enriched air.

[0044] The process of the invention comprises the steps of using the combustion gas stream to drive a gas turbine and produce an oxygen-containing exhaust gas stream. Thus, the oxygen-containing exhaust gas stream is the exhaust gas from the gas turbine.

[0045] The process of the present invention can be used with any type of gas turbine. The combustion of the hydrogen-containing stream with the oxygen-containing feed to produce the combustion gas stream can be carried out in a hydrogen combustion zone. The hydrogen combustion zone can be incorporated into the gas turbine or can be located outside the gas turbine. Typically, the hydrogen combustion zone can be incorporated into the gas turbine.

[0046] Typically, in the process of the invention the gas turbine and the ammonia cracking reactor are separate plant components.

[0047] The oxygen-containing exhaust gas stream may have a temperature of 500°C to 800°C, 500°C to 750°C, or 600°C to 700°C, such as about 650°C.

[0048] The oxygen-containing waste gas stream may contain oxygen in an amount greater than 5 mol%, greater than 8 mol%, greater than 11 mol%, or greater than 13 mol%. The oxygen-containing waste gas stream may contain oxygen in an amount less than 25 mol%, less than 22 mol%, less than 20 mol%, or less than 18 mol%. For example, the oxygen-containing waste gas stream may contain oxygen in an amount of 5 mol% to 25 mol%, 8 mol% to 22 mol%, 11 mol% to 20 mol%, or 13 mol% to 18 mol%, such as about 15 mol% or about 16 mol%.

[0049] In a preferred process of the present invention, the gas turbine can be used to generate power, such as electricity and / or mechanical power. The gas turbine can generate power directly or indirectly. For example, the gas turbine can be coupled to any suitable generator for generating electricity, and / or the gas turbine can be coupled to a compressor for generating mechanical power.

[0050] The process of the invention comprises the step of supplying at least a portion of the oxygen-containing waste gas to a fuel combustion zone. The fuel combustion zone may be located in or fluidly connected to the ammonia cracking reactor such that combustion provides heat for the ammonia cracking reaction.

[0051] The fuel combustion zone may be located within the ammonia cracking reactor or may be located in a separate vessel for combustion. The combustion of the fuel generates heat that is used to support the endothermic ammonia cracking reaction.

[0052] The fuel combustion zone may suitably be a radiant section in a box furnace of the ammonia cracking reactor. Thus, the fuel combustion zone may provide thermal energy (e.g. radiant heat) to the ammonia cracking reactor. Alternatively, if the fuel combustion zone is located in a separate vessel from the ammonia cracking furnace, the ammonia cracking furnace may be a heat exchange design, such as a gas heated reformer or a compact reformer, in which the catalyst-containing tubes are heated by convection from hot combustion gases flowing around the outer surface of the tubes.

[0053] As will be readily appreciated, the fuel combustion zone is used to provide the thermal energy required to catalytically crack the ammonia in the ammonia stream to produce the hydrogen-containing stream.

[0054] The oxygen-containing exhaust gas stream may be supplied to the fuel combustion zone at a temperature of 500°C to 800°C, 500°C to 750°C, or 600°C to 700°C, such as about 650°C.

[0055] Those skilled in the art can calculate the portion of the oxygen-containing waste gas stream that needs to be supplied to the fuel combustion zone. Typically, the portion of the oxygen-containing waste gas stream supplied to the fuel combustion zone may be greater than 5%, greater than 7%, greater than 8%, or greater than 9% of the total waste gas stream leaving the gas turbine. Typically, the portion of the oxygen-containing waste gas stream supplied to the fuel combustion zone may be less than 75%, less than 50%, less than 30%, or less than 20% of the total waste gas stream leaving the gas turbine. For example, the portion of the oxygen-containing waste gas stream supplied to the fuel combustion zone may be 5% to 75%, 7% to 50%, 8% to 30%, or 9% to 20% of the total waste gas stream leaving the gas turbine. For example, it may be preferred that the portion of the oxygen-containing waste gas stream supplied to the fuel combustion zone is 10% to 15% or 11% to 13% of the total waste gas stream leaving the gas turbine.

[0056] The process of the present invention comprises the steps of combusting a fuel stream with an oxygen-containing exhaust gas stream in a fuel combustion zone to generate heat energy for an ammonia cracking reactor.

[0057] The fuel stream used to provide heat for the ammonia cracking reaction can be a carbon-free fuel stream. As used herein, the term "carbon-free fuel stream" is understood to include combustible compounds that do not contain carbon, such as ammonia and hydrogen. In the preferred process of the present invention, the fuel stream contains ammonia. The amount of ammonia in the fuel stream is not particularly limited, for example, the fuel stream may contain 1mol% to 100mol% of the total fuel stream, such as 5mol% to 75mol%, 10mol% to 50mol% or 15mol% to 30mol% of the total fuel stream. Preferably, the fuel stream contains ammonia in an amount greater than 10mol%, greater than 12mol% or greater than 15mol%. The fuel stream preferably contains less than 45mol%, less than 35mol% or less than 35mol% of the total fuel stream. For example, the fuel stream preferably contains ammonia in an amount of 10mol% to 45mol%, 12mol% to 35mol% or 15mol% to 25mol% of the total fuel stream.

[0058] When the fuel stream comprises ammonia, the ammonia-containing fuel stream may be supplied from the same or a different source as the ammonia stream supplied to the ammonia cracking reactor.When the fuel stream comprises ammonia, the ammonia-containing fuel stream is preferably supplied from the same source as the ammonia stream supplied to the ammonia cracking reactor.

[0059] The fuel stream may include one or more additional fuel sources. The additional fuel source is not necessarily a carbon-free fuel source, however, the additional fuel source is preferably a carbon-free fuel source. The additional fuel source may include one or more of the following: hydrogen, natural gas, methane, refinery waste gas, biogas, tail gas from a hydrogen purification unit, or a portion of a hydrogen-containing stream from an ammonia cracking reactor. As described above, the preferred process of the present invention includes a purification unit for producing a hydrogen-rich stream and tail gas. In a particularly preferred process of the present invention, the additional fuel source includes tail gas from a purification unit for producing a hydrogen-rich stream. Therefore, in a particularly preferred process of the present invention, the process includes the following steps: feeding a hydrogen-containing stream to a purification unit and increasing the hydrogen content of the hydrogen-containing stream to produce a hydrogen-rich stream and tail gas; feeding the tail gas to a fuel combustion zone; and burning the fuel stream and the tail gas with the oxygen-containing waste gas.

[0060] One advantage of the present invention is that tail gas from the purification unit used to produce the hydrogen-rich feed, as well as the fuel stream, can be combusted with the oxygen-containing waste gas. It has been unexpectedly discovered that using the tail gas in this manner improves the overall efficiency of the process of the present invention by maximizing the amount of combustible fuel recovered from the process and reducing the loss of combustible and / or toxic chemicals (e.g., ammonia) to the atmosphere.

[0061] The additional fuel source can be present in the fuel stream in any suitable amount under conditions that maintain the fuel stream combustible with the oxygen-containing exhaust gas stream.

[0062] In a preferred process of the present invention, the fuel stream is preheated before combustion in the fuel combustion zone. The fuel stream may be preheated to any temperature below the autoignition temperature of the fuel stream. For example, the fuel stream may be preheated to a temperature greater than 100°C, greater than 150°C, or greater than 200°C. The fuel stream may be preheated to a temperature less than the autoignition temperature of the fuel stream, such as less than 400°C, less than 350°C, or less than 300°C. For example, the fuel stream may be preheated to a temperature from 100°C to the autoignition temperature of the fuel stream, such as from 100°C to 400°C. In a preferred process of the present invention, the fuel stream is an ammonia-containing fuel stream and is provided from a preheated ammonia stream.

[0063] The ratio of the fuel stream to the oxygen-containing exhaust gas stream before combustion in the fuel combustion zone may be appropriately selected to allow efficient combustion of the fuel stream. The ratio of the fuel stream to the oxygen-containing exhaust gas stream before combustion in the fuel combustion zone may depend on the amount of oxygen present in the oxygen-containing exhaust gas stream. For example, where the fuel stream is pure ammonia and the oxygen-containing exhaust gas contains 13.2 mol% oxygen, the ratio of the fuel stream to the oxygen-containing exhaust gas stream before combustion in the fuel combustion zone may be selected to be in the range of 1:6 to 1:7, such as 1:6.5.

[0064] Preferably, the heat energy generated by the combustion of the oxygen-containing waste gas stream in the fuel combustion zone provides up to 100% of the heat energy required for the ammonia cracking reactor to crack the ammonia in the ammonia stream, such as up to 95%, up to 90%, up to 85% or up to 80% of the heat energy required for the ammonia cracking reactor to crack the ammonia in the ammonia stream. Preferably, the heat energy generated by the combustion of the oxygen-containing waste gas stream in the fuel combustion zone provides more than 50% of the heat energy required for the ammonia cracking reactor to crack the ammonia in the ammonia stream, such as more than 60%, more than 70% or more than 75% of the heat energy required for the ammonia cracking reactor to crack the ammonia in the ammonia stream. For example, it is preferred that the heat energy generated by the combustion of the oxygen-containing waste gas stream in the fuel combustion zone provides more than 50% and up to 100% of the heat energy required for the ammonia cracking reactor.

[0065] Optionally, the process of the present invention may include a step of passing a portion of the oxygen-containing waste gas into a heat recovery zone such as a heat recovery steam generator. If desired, any unburned ammonia or nitrogen oxides in the oxygen-containing waste gas may be scrubbed or reacted from the oxygen-containing gas before the oxygen-containing waste gas is passed into the fuel combustion zone.

[0066] The combustion in the fuel combustion zone produces flue gas which can be recovered from the ammonia cracking reactor. The flue gas can be cooled in one or more cooling stages and subjected to one or more purification stages before being discharged into the atmosphere. The one or more cooling stages can include a preheating stage for one or more reactants in the ammonia cracking reactor and / or the reactants that produce steam. The one or more purification stages can include a selective catalytic reduction or SCR stage, in which nitrogen oxides react with ammonia to form nitrogen and water vapor. Any flue gas selective catalytic reduction technology can be used.

[0067] In certain embodiments of the process of the present invention, the process comprises the following steps:

[0068] supplying an ammonia stream to an ammonia cracking reactor;

[0069] cracking ammonia in the ammonia stream in the ammonia cracking reactor to produce a hydrogen-containing stream;

[0070] optionally feeding the hydrogen-containing stream to a purification unit, such as a pressure swing adsorption unit, and increasing the hydrogen content to produce a hydrogen-rich stream and a tail gas;

[0071] optionally feeding the hydrogen-rich stream to a steam generation unit and / or a heat recovery zone;

[0072] combining a hydrogen-rich stream with an oxygen-containing feed and combusting the hydrogen-rich stream with the oxygen-containing feed to produce a combusted gas stream;

[0073] using the combustion gas stream to drive a gas turbine and produce an oxygen-containing exhaust gas stream;

[0074] supplying at least a portion of the oxygen-containing waste gas stream to a fuel combustion zone;

[0075] optionally supplying an additional fuel source to the fuel combustion zone; and

[0076] The fuel stream and optionally an additional fuel source are combusted with the oxygen-containing exhaust gas stream in the fuel combustion zone to generate heat energy for the ammonia cracking reactor.

[0077] In certain embodiments of the process of the present invention, the process comprises the following steps:

[0078] supplying an ammonia stream to an ammonia cracking reactor;

[0079] cracking ammonia in the ammonia stream in the ammonia cracking reactor to produce a hydrogen-containing stream;

[0080] feeding the hydrogen-containing stream to a purification unit, such as a pressure swing adsorption unit, and increasing the hydrogen content to produce a hydrogen-rich stream and a tail gas;

[0081] optionally feeding the hydrogen-rich stream to a steam generation unit and / or a heat recovery zone;

[0082] combining a hydrogen-rich stream with an oxygen-containing feed and combusting the hydrogen-rich stream with the oxygen-containing feed to produce a combusted gas stream;

[0083] using the combustion gas stream to drive a gas turbine and produce an oxygen-containing exhaust gas stream;

[0084] supplying at least a portion of the oxygen-containing waste gas stream to a fuel combustion zone;

[0085] optionally supplying an additional fuel source to the fuel combustion zone;

[0086] feeding the tail gas to a fuel combustion zone; and

[0087] The fuel stream and tail gas and optionally an additional fuel source are combusted with the oxygen-containing waste gas stream in the fuel combustion zone to generate heat energy for the ammonia cracking reactor.

[0088] Figure 1 A block flow diagram of a process not according to the invention comprising a non-integrated gas turbine is shown. Figure 1 The flow diagram of FIG. 1 shows that ammonia (1) is fed to an ammonia preheating and evaporation zone (2) outside the ammonia cracking reactor, where the ammonia is evaporated. The preheated and evaporated ammonia is fed to an ammonia superheating zone (3) and a cracker combustion zone (13). Figure 1In the flow chart of , the ammonia cracking reactor (4), the ammonia superheating zone (3) and the cracker combustion zone (13) are all part of the same equipment. Ammonia from the ammonia superheating zone (3) is fed to the ammonia cracking reactor (4) to produce a hydrogen-containing stream. The hydrogen-containing stream is fed to the steam generator (5) and the heat recovery zone (6). The hydrogen-containing stream from the heat recovery zone (6) is fed to the gas turbine (7), in which the hydrogen-containing stream is burned in the presence of an oxygen-containing feed, which is air (17) that has been compressed by a compressor (8). Steam from the steam generator (5) and exhaust gas from the gas turbine (7) are used to generate electricity (10). Heat from the exhaust gas from the gas turbine (5) is recovered by the heat recovery steam generator (9). In the fuel combustion zone (13), the ammonia fuel is combined with preheated air from the air preheating zone (12). Ammonia fuel and preheated air are burned in the fuel combustion zone (13) to generate heat energy for the ammonia cracking reactor (4). The exhaust gas from the ammonia cracking reactor (4) is recovered in the heat recovery zone (14), and the exhaust gas is sent to the chimney (15) to be discharged as flue gas (16). The heat from the heat recovery zone (14) is used in the ammonia preheating and evaporation zone (2) and the air preheating zone (12) (not shown for clarity). One or more process streams can be heated in the heat recovery zone (14) by exchange with the exhaust gas.

[0089] Figure 2 A block flow diagram of a process according to the invention comprising an integrated gas turbine is shown. Figure 2 The flow diagram of FIG. 1 shows that ammonia (21) is fed to an ammonia preheating and evaporation zone (22) outside the ammonia cracking reactor, where the ammonia is evaporated. The preheated and evaporated ammonia is fed to an ammonia superheating zone (23) and a fuel combustion zone (213). Figure 2In the flow chart of , the ammonia cracking reactor (24), the ammonia superheating zone (23) and the fuel combustion zone (213) are all part of the same equipment. Ammonia from the ammonia superheating zone (23) is fed to the ammonia cracking reactor (24) to produce a hydrogen-containing stream. The hydrogen-containing stream is fed to the steam generator (25) and the heat recovery zone (26). The hydrogen-containing stream from the heat recovery zone (26) is fed to the gas turbine (27), in which the hydrogen-containing stream is burned in the presence of an oxygen-containing feed, which is air (217) that has been compressed by a compressor (28). Steam from the steam generator (25) and a portion of the exhaust gas from the gas turbine (27) are used to generate electricity (210). A portion of the heat from the exhaust gas from the gas turbine (25) is recovered by the heat recovery steam generator (29). In the fuel combustion zone (213), the ammonia fuel is combined with a portion of the oxygen-containing exhaust gas from the gas turbine (27). Ammonia fuel and oxygen-containing waste gas are burned in the fuel combustion zone (213) to generate heat energy for the ammonia cracking reactor (24). The waste gas from the ammonia cracking reactor (24) is recovered in the heat recovery zone (214), and the waste gas is sent to the chimney (215) to be discharged as flue gas (216). The heat from the heat recovery zone (214) is used for the ammonia preheating and evaporation zone (22) (not shown for clarity).

[0090] Example

[0091] In order to demonstrate the efficiency savings of the process of the present invention, Figure 1 Flowchart of a non-integrated gas turbine (not according to the invention) and Figure 2 The simulation was performed by comparing a flow chart including an integrated gas turbine (according to the invention).

[0092] For both flow charts, the following assumptions are made:

[0093] ● Use the same ammonia cracking reactor and gas turbine for both flowsheets

[0094] The energy requirements of the ammonia cracking reactor are met by combustion of ammonia, with the total amount of ammonia available for the entire system set at 1,200 metric tons per day (MTPD)

[0095] ●The inlet ammonia temperature of the cracker is 600℃

[0096] ●The inlet ammonia temperature of the combustion side of the cracker is 90℃

[0097] ●Ambient air temperature is 10℃

[0098] • The fuel requirement was set to achieve 0.58% ammonia slip for both flowsheets.

[0099] • The flue gas from the HRSG is set to 280°C and the HPS is raised in the HRSG.

[0100] unit Non-integrated system (comparative example) Integrated system (according to the present invention) Cracker feed ammonia MTPD 900 963 Fuel Ammonia MTPD 300 237 Total Ammonia MTPD 1200 1200 Energy in Ammonia* MW 258 258 Air compressor power MW -119 -127 GT Power MW 181 194 HRSG Power MW 29 27 Net output** MW 91 94 <![CDATA[Net output per te NH3]]> kW / te 75.9 78.1 Energy efficiency*** ％ 35.3 36.3

[0101] *Total energy in all ammonia streams, based on ammonia's LHV of 316,449.8 kJ / kmol.

[0102] ** Energy requirements for rotating equipment (excluding air compressors) and energy generated by generating steam through cracked gas heat recovery are not included in this analysis. Due to the higher outlet temperature and higher flow rate of cracked gas in the integrated system, the energy generated will be higher than that of the non-integrated system

[0103] ***Based on the following formula:

[0104]

[0105] The above simulations show that the system including the integrated gas turbine according to the present invention has higher energy efficiency and produces more electricity for output per unit of ammonia fed to the system compared to a non-integrated gas turbine.

Claims

1. A process for generating electricity using a gas turbine fueled by a carbon-free fuel derived from catalytic cracking of ammonia, the process comprising: supplying an ammonia stream to an ammonia cracking reactor; cracking ammonia in the ammonia stream in the ammonia cracking reactor to produce a hydrogen-containing stream; combining the hydrogen-containing stream with an oxygen-containing feed and combusting the hydrogen-containing stream with the oxygen-containing feed to produce a combusted gas stream; using the combustion gas stream to drive a gas turbine and produce an oxygen-containing exhaust gas stream; supplying at least a portion of the oxygen-containing waste gas stream to a fuel combustion zone; as well as A fuel stream and the oxygen-containing exhaust gas stream are combusted in the fuel combustion zone to generate heat energy for the ammonia cracking reactor.

2. The process according to claim 1, further comprising the step of preheating the ammonia stream to a temperature of 350°C to 1000°C.

3. A process according to claim 1 or claim 2, wherein the temperature of the ammonia stream at the inlet of the ammonia cracking reactor is in the range of 350°C to 1000°C, 400 to 950°C, 450°C to 850°C or 500°C to 750°C.

4. A process according to any one of the preceding claims, wherein the hydrogen-containing stream comprises 40 mol% to 75 mol% hydrogen.

5. The process according to any one of the preceding claims, further comprising the step of feeding the hydrogen-containing stream to a purification unit and increasing the hydrogen content of the hydrogen-containing stream to produce a hydrogen-rich stream and a tail gas.

6. The process of claim 5, wherein the hydrogen-rich stream comprises 50 mol% to 100 mol% hydrogen.

7. A process according to any one of the preceding claims, wherein the oxygen-containing feed is a compressed oxygen-containing feed.

8. A process according to any one of the preceding claims, wherein the oxygen-containing feed is air, oxygen or oxygen-enriched air.

9. A process according to any one of the preceding claims, wherein the oxygen-containing waste gas stream may comprise oxygen in an amount of greater than 5 mol% to 25 mol%.

10. A process according to any one of the preceding claims, wherein the temperature is between 500°C and 800°C. The oxygen-containing exhaust gas stream is supplied to the fuel combustion zone at a temperature of 500°C to 750°C or 600°C to 700°C.

11. A process according to any one of the preceding claims, wherein the portion of the oxygen-containing exhaust gas stream supplied to the fuel combustion zone is 5% to 75%, 7% to 50%, 8% to 30% or 9% to 20% of the total exhaust gas stream leaving the gas turbine.

12. A process according to any one of the preceding claims, wherein the fuel stream comprises ammonia.

13. A process according to any one of the preceding claims, wherein the fuel stream comprises from 1 mol% to 100 mol% of the total fuel stream, preferably from 5 mol% to 75 mol% of the total fuel stream. Ammonia in an amount of 10 mol % to 50 mol % or 15 mol % to 30 mol %.

14. A process according to any one of claims 5 to 13, wherein the process comprises the steps of feeding the tail gas to the fuel combustion zone; and combusting the fuel stream and the tail gas with the oxygen-containing waste gas.

15. A process according to any one of the preceding claims, wherein the fuel stream comprises one or more additional fuel sources selected from the group consisting of: hydrogen, natural gas, methane, refinery off-gas, biogas, the tail gas from the hydrogen purification unit and a portion of the hydrogen-containing stream from the ammonia cracking reactor.

16. The process according to any one of claims 12 to 15, wherein the fuel stream comprises ammonia and the ammonia-containing fuel stream is supplied from the same source as the ammonia stream supplied to the ammonia cracking reactor.

17. A process according to any one of the preceding claims, wherein more than 50% and up to 100% of the thermal energy required for the ammonia cracking reactor is provided by using the thermal energy generated by combustion of the oxygen-containing waste gas stream in the combustion zone.

18. A method for improving an ammonia production facility, the method comprising the steps of implementing the process of any one of claims 1 to 17 in an ammonia production facility.

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