Power generation methods in gas turbines

Abstract

A method for providing thermal energy to an ammonia decomposition reactor. The present invention includes the steps of recovering oxygen-containing offgas from a gas turbine fueled by hydrogen and supplying at least a portion of the offgas to a fuel combustion zone to generate thermal energy for the ammonia decomposition reactor. The present invention is used in chemical manufacturing facilities such as ammonia production facilities.

Description

Technical Field

[0001] The present invention relates to a method for cracking ammonia. More specifically, the present invention relates to a method for providing heat to an ammonia decomposition reactor. The present invention further relates to a method for retrofitting an ammonia plant using the method 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 electrical energy. Among such carbon-free fuels, ammonia has attracted attention for carbon-free power generation at ammonia production facilities where ammonia is abundantly supplied. However, the development of gas turbine systems fueled by ammonia remains in an early stage. Many commercially available gas turbines are not supplied as suitable for use with ammonia fuel.

[0003] A potential solution for using ammonia directly as fuel is to decompose ammonia to form a mixture of hydrogen and nitrogen, allowing the gas turbine to be driven by the combustion of hydrogen.

[0004] The decomposition of ammonia into hydrogen and nitrogen has been used for many years in ammonia plants to provide hydrogen and activate catalysts. The reaction can be represented as follows.

[0005] Formula

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

[0007] The combustion of hydrogen streams in gas turbines is well known. U.S. Patent Publications 2022162999 and 2022162989 disclose a method including a gas turbine driven by the combustion of a hydrogen-containing stream and a compressed air stream. The hydrogen-containing stream is generated in an ammonia decomposition unit supplied 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 either supplied directly to the decomposition unit or used to preheat the ammonia stream upstream of the decomposition unit through a heat exchanger.

[0008] The need to improve the efficiency of gas turbines powered by the combustion of carbon-free fuels, particularly ammonia-derived fuels, remains. [Overview of the project]

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

[0010] Therefore, in a first aspect of the present invention, a method for generating electricity using a gas turbine fueled by a carbon-free fuel obtained from the catalytic decomposition of ammonia, The process of supplying an ammonia stream to the ammonia decomposition reactor, A process of decomposing ammonia in an ammonia stream in an ammonia decomposition reactor to generate a hydrogen-containing stream, A process of combining a hydrogen-containing flow with an oxygen-containing feed, burning the hydrogen-containing flow together with the oxygen-containing feed, and generating a burnt gas flow. A process of using a combustion gas flow to drive a gas turbine and generate an oxygen-containing off-gas flow, A step of supplying at least a portion of the oxygen-containing off-gas flow to the fuel combustion zone, A method is provided which includes the step of burning a fuel stream and an oxygen-containing off-gas stream within a fuel combustion zone to generate thermal energy for an ammonia decomposition reactor.

[0011] Surprisingly, it was found that the off-gas flow from the gas turbine contains enough oxygen to be used for combustion of the fuel flow in the fuel combustion zone. Furthermore, because the oxygen-containing off-gas exits the gas turbine at a high temperature, there is little to no need to preheat it before combustion with the fuel flow. Surprisingly, it was found that unexpected energy savings can be achieved in the method of the present invention by supplying the thermal energy generated from the combustion of the fuel flow and the oxygen-containing off-gas to the ammonia decomposition reactor.

[0012] A further advantage of the method of the present invention is that it can also reduce the cost of capital equipment. For example, since at least a portion of the oxygen-containing off-gas is used in the combustion of the fuel flow, less energy needs to be recovered from the remaining oxygen-containing off-gas that is not used in the combustion of the fuel flow. In other words, smaller and less expensive equipment (e.g., heat recovery equipment such as heat recovery steam generators) can be specified.

[0013] The gas turbine described in this invention is sometimes called an integrated gas turbine because the generated oxygen-containing off-gas flow is recovered and supplied to the fuel combustion zone. In contrast, references to non-integrated gas turbines also include methods in which the oxygen-containing off-gas flow generated from the gas turbine is not used for combustion.

[0014] The method of the present invention is particularly suitable for implementation within or near ammonia production or storage facilities, where the supply of ammonia can serve as input to an ammonia decomposition reactor, generate hydrogen gas in a hydrogen-containing stream, and be provided as a fuel stream that is burned together with an oxygen-containing off-gas stream, thereby supplying heat to the ammonia decomposition reactor. However, the method of the present invention is not limited to implementation in ammonia production facilities and can be used in any suitable environment where ammonia can be supplied.

[0015] Another aspect of the present invention provides a method for modifying an ammonia production facility by implementing the method of the first aspect of the present invention in the ammonia production facility. [Brief explanation of the drawing]

[0016] [Figure 1] A block flow diagram of the comparative method, which includes a non-integrated gas turbine, is shown. [Figure 2] A block flow diagram of the method of the present invention, which includes an integrated gas turbine, is shown. [Modes for carrying out the invention]

[0017] The preferred and / or optional features of the present invention are described below. Any aspect of the present invention can be combined with any other aspect of the present invention unless otherwise required by context. Any preferred and / or optional feature of any aspect can be combined with any aspect of the present invention, either individually or in combination, unless otherwise required by context.

[0018] The method of the present invention includes the step of supplying an ammonia stream to an ammonia decomposition reactor.

[0019] The ammonia stream can be obtained from any source. In a preferred method of the present invention, the ammonia stream is generated by a catalytic combination of hydrogen and nitrogen, for example, the ammonia stream can be generated from a Haber-Bosch ammonia synthesis process. In a preferred method of the present invention, the ammonia stream can be generated in an ammonia production facility located upstream of an ammonia decomposition reactor. Alternatively, the ammonia stream can be supplied from an ammonia gas storage facility or an ammonia gas pipeline.

[0020] In a preferred method of the present invention, the ammonia stream may be preheated before being fed to the ammonia cracking reactor. Accordingly, the method of the present invention may comprise the step of preheating the ammonia stream. The ammonia stream may be preheated to a temperature above 350°C, above 400°C, above 450°C, above 500°C, or above 550°C. The ammonia stream may be preheated to a temperature below 1000°C, below 950°C, below 850°C, below 750°C, or below 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, for example 550°C to 700°C.

[0021] Suitable ammonia cracking reactors are known in the art, and may include a box-type furnace that provides a radiation section comprising one or more burners to which a fuel stream and an oxygen supply gas, for example air, are fed. The radiation section comprises one or more catalyst-containing tubes through which the ammonia stream passes. Combustion of the fuel stream in the one or more burners generates radiant heat for heating the one or more reaction tubes containing the ammonia cracking catalyst. Dozens or hundreds of tubes may be present in the radiation section. If desired, downstream of the radiation section, the combustion gas may be used to preheat one or more feed streams in a convection section. Reactors comprising a radiation section containing reaction tubes and a convection section for preheating feed are known in the art for steam methane reforming and can be applied to the present invention.

[0022] For example, alternative ammonia cracking reactors may also be used where combustion of fuel in a fuel combustion zone is split into reactors provided with catalyst-containing tubes. Such a reactor is the compact reformer available from Johnson Matthey Davy Technologies Limited.

[0023] The catalyst may be any ammonia decomposition catalyst. Nickel catalysts and ruthenium catalysts may be used. A preferred catalyst is a nickel catalyst. The catalyst may comprise, expressed as NiO, 3 to 30% by weight of nickel, preferably 8 to 20% by weight of nickel, on a suitable refractory support, for example alumina or a metal aluminate. The catalyst may be in the form of pelletized units, which may contain one or more through-holes, or may be provided as a washcoat on a structured metal or ceramic catalyst. A particularly preferred catalyst is KATALCO® 27-2 available from Johnson Matthey PLC, which comprises 12% nickel expressed as NiO on cylindrical pellets formed from a high surface area alumina support.

[0024] The method of the present invention comprises the step of decomposing ammonia in an ammonia stream in an ammonia decomposition reactor to produce a hydrogen-containing stream.

[0025] The temperature of the ammonia stream at the inlet of the ammonia decomposition 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, for example 550°C to 700°C. The temperature of the hydrogen-containing stream exiting the ammonia decomposition reactor affects the equilibrium position of the decomposition reaction and may range from 500 to 950°C. When a nickel catalyst is used in the ammonia decomposition reactor, the temperature of the hydrogen-containing stream exiting the ammonia decomposition reactor may preferably be greater than about 700°C.

[0026] The inlet pressure to the ammonia decomposition reactor is set by the flow sheet design and may range from 1 to 100 bar absolute, preferably 10 to 90 bar absolute, for example 31 to 51 bar absolute.

[0027] The ammonia decomposition reaction produces a hydrogen-containing stream, which also contains nitrogen and may contain residual ammonia.

[0028] A hydrogen-containing stream may contain 40 mol% or more of hydrogen, 50 mol% or more of hydrogen, or 60 mol% or more of hydrogen. A hydrogen-containing stream may contain 75 mol% or less of hydrogen, 70 mol% or less of hydrogen, or 65 mol% or less of hydrogen. For example, a hydrogen-containing stream may contain 40 mol% to 75 mol% of hydrogen, 50 mol% to 70 mol% of hydrogen, or 60 mol% to 65 mol% of hydrogen.

[0029] The hydrogen-containing stream can optionally be supplied to a purification unit, such as a pressure swing absorption unit, to separate hydrogen from other components and increase its hydrogen content. Therefore, the method of the present invention may include the step of supplying a hydrogen-containing stream to a purification unit to increase the hydrogen content of the hydrogen-containing stream and generate a hydrogen-enriched stream and tail gas.

[0030] Hydrogen-enriched streams may contain 50 mol% or more of hydrogen, 60 mol% or more of hydrogen, or 75 mol% or more of hydrogen. Hydrogen-enriched streams may contain 100 mol% or less of hydrogen, 90 mol% or less of hydrogen, or 80 mol% or less of hydrogen. For example, hydrogen-enriched streams may contain 50 mol% to 100 mol% of hydrogen, 60 mol% to 90 mol% of hydrogen, or 70 mol% to 80 mol% of hydrogen, for example, about 75 mol% of hydrogen.

[0031] The tail gas may contain nitrogen and small amounts of ammonia and hydrogen. For example, the tail gas may contain nitrogen, 1 mol% to 10 mol% of ammonia (e.g., less than about 5 mol%), and 2 mol% to 40 mol% of hydrogen (e.g., 15 mol% to 25 mol%).

[0032] As used herein, the term "hydrogen-containing flow" may be used to refer to either a hydrogen-containing flow or a hydrogen-enriched flow.

[0033] The hydrogen-containing stream may be supplied to a steam generation unit and / or heat recovery zone before being combusted together with an oxygen-containing feedstock. As will be understood by those skilled in the art, the steam generation unit and / or heat recovery zone may be used to recover low or moderate amounts of heat.

[0034] It is desirable to separate residual ammonia from the hydrogen-containing stream before burning it together with the oxygen-containing feedstock. Ammonia removal can be achieved, for example, by washing with water using a conventional washing device.

[0035] The method of the present invention includes the step of combining a hydrogen-containing flow with an oxygen-containing feed, and burning the hydrogen-containing flow together with the oxygen-containing feed to generate a burnt gas flow.

[0036] The oxygen-containing feed can be air, oxygen, or oxygen-enriched air. In a preferred method 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.

[0037] The method of the present invention includes the step of driving a gas turbine using a combustion gas flow to generate an oxygen-containing off-gas flow. Therefore, the oxygen-containing off-gas flow is the exhaust gas from the gas turbine.

[0038] The method of the present invention can be used with any type of gas turbine. Combustion of a hydrogen-containing flow and an oxygen-containing feed to generate a combusted gas flow can be carried out in a hydrogen combustion zone. The hydrogen combustion zone may be incorporated inside the gas turbine or it may be located outside the gas turbine. Typically, the hydrogen combustion zone can be incorporated inside the gas turbine.

[0039] Typically, in the method of the present invention, the gas turbine and the ammonia decomposition reactor are separate pieces of equipment.

[0040] The oxygen-containing off-gas stream may have a temperature of 500°C to 800°C, 500°C to 750°C, or 600°C to 700°C, for example, about 650°C.

[0041] An oxygen-containing off-gas stream may contain oxygen in amounts greater than 5 mol%, greater than 8 mol%, greater than 11 mol%, or greater than 13 mol%. An oxygen-containing off-gas stream may contain oxygen in amounts less than 25 mol%, less than 22 mol%, less than 20 mol%, or less than 18 mol%. For example, an oxygen-containing off-gas stream may contain oxygen in amounts of 5 mol% to 25 mol%, 8 mol% to 22 mol%, 11 mol% to 20 mol%, or 13 mol% to 18 mol%, for example, about 15 or about 16 mol%.

[0042] In a preferred method of the present invention, a 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 connected to any suitable generator for generating electricity, and / or the gas turbine can be connected to a compressor for generating mechanical power.

[0043] The method of the present invention includes the step of supplying at least a portion of an oxygen-containing off-gas to a fuel combustion zone. The fuel combustion zone may be located within an ammonia decomposition reactor, or may be fluidly connected to an ammonia decomposition reactor, so that the combustion provides heat for the ammonia decomposition reaction.

[0044] The fuel combustion zone may be located within the ammonia decomposition reactor or in a separate combustion vessel. The combustion of the fuel generates heat, which is used to support the endothermic ammonia decomposition reaction.

[0045] The fuel combustion zone may preferably be the radiating section within the box-type furnace of the ammonia decomposition reactor. Thus, the fuel combustion zone can supply thermal energy (e.g., radiant heat) to the ammonia decomposition reactor. Alternatively, if the fuel combustion zone is in a separate vessel from the ammonia decomposition reactor, the ammonia decomposition reactor may be a heat exchange design such as a gas-heated reformer or a small reformer, in which case the catalyst containment tube is heated by convection from the hot combustion gas passing around the outer surface of the tube.

[0046] As is easily understood, the fuel combustion zone functions to provide the necessary thermal energy to catalytically decompose ammonia in the ammonia stream and generate a hydrogen-containing stream.

[0047] The oxygen-containing off-gas stream can be supplied to the fuel combustion zone at temperatures of 500°C to 800°C, 500°C to 750°C, or 600°C to 700°C, for example, around 650°C.

[0048] Those skilled in the art can calculate the portion of the oxygen-containing off-gas flow that needs to be supplied to the fuel combustion zone. Typically, the portion of the oxygen-containing off-gas flow supplied to the fuel combustion zone may be more than 5%, more than 7%, more than 8%, or more than 9% of the total off-gas flow leaving the gas turbine. Typically, the portion of the oxygen-containing off-gas flow supplied to the fuel combustion zone may be less than 75%, less than 50%, less than 30%, or less than 20% of the total off-gas flow leaving the gas turbine. For example, the portion of the oxygen-containing off-gas flow supplied to the fuel combustion zone may be 5% to 75%, 7% to 50%, 8% to 30%, or 9% to 20% of the total off-gas flow leaving the gas turbine. For example, it may be preferable that the portion of the oxygen-containing off-gas flow supplied to the fuel combustion zone be 10% to 15% or 11% to 13% of the total off-gas flow leaving the gas turbine.

[0049] The method of the present invention includes the step of burning a fuel flow together with an oxygen-containing off-gas flow in a fuel combustion zone to generate thermal energy for an ammonia decomposition reactor.

[0050] The fuel flow used to provide heat for the ammonia decomposition reaction may be a carbon-free fuel flow. As used herein, the term "carbon-free fuel flow" is understood to include a carbon-free combustible compound, such as ammonia and hydrogen. In the preferred method of the present invention, the fuel flow contains ammonia. The amount of ammonia in the fuel flow is not particularly limited, and for example, the fuel flow may contain 1 mol% to 100 mol% of the total fuel flow, for example, 5 mol% to 75 mol%, 10 mol% to 50 mol%, or 15 mol% to 30 mol% of the total fuel flow. Preferably, the fuel flow contains more than 10 mol%, more than 12 mol%, or more than 15 mol% of the ammonia. Preferably, the fuel flow contains less than 45 mol%, less than 35 mol%, or less than 35 mol% of the total fuel flow. For example, the fuel flow preferably contains 10 mol% to 45 mol%, 12 mol% to 35 mol%, or 15 mol% to 25 mol% of the total fuel flow.

[0051] If the fuel flow contains ammonia, the ammonia-containing fuel flow may be supplied from the same source as the ammonia flow supplied to the ammonia decomposition reactor, or from a different source. If the fuel flow contains ammonia, the ammonia-containing fuel flow is preferably supplied from the same source as the ammonia flow supplied to the ammonia decomposition reactor.

[0052] The fuel flow may include one or more additional fuel sources. The additional fuel sources are not necessarily carbon-free fuel sources, but are preferably carbon-free fuel sources. The additional fuel sources may include one or more of the following: hydrogen, natural gas, methane, refinery off-gas, biogas, tail gas from a hydrogen purification unit, or a portion of a hydrogen-containing flow from an ammonia decomposition reactor. As described above, a preferred method of the present invention includes a purification unit used to produce a hydrogen-enriched flow and tail gas. In a particularly preferred method of the present invention, the additional fuel source includes tail gas from a purification unit used to produce a hydrogen-enriched flow. Therefore, in a particularly preferred method of the present invention, the method includes the steps of: supplying a hydrogen-containing flow to a purification unit to increase the hydrogen content of the hydrogen-containing flow to produce a hydrogen-enriched flow and tail gas; supplying the tail gas to a fuel combustion zone; and burning the fuel flow and tail gas together with an oxygen-containing off-gas.

[0053] An advantage of the present invention is that the tail gas from the purification unit used to produce the hydrogen enrichment feed, and the fuel stream, can be burned together with an oxygen-containing off-gas. It was unexpectedly found that using the tail gas in this manner improves the overall efficiency of the method 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) into the atmosphere.

[0054] An additional fuel source can be present in the fuel flow in any suitable amount, as long as the fuel flow remains combustible together with the oxygen-containing off-gas flow.

[0055] In a preferred method of the present invention, the fuel flow is preheated before being burned in the fuel combustion zone. The fuel flow may be preheated to any temperature below the autoignition temperature of the fuel flow. For example, the fuel flow may be preheated to a temperature above 100°C, above 150°C, or above 200°C. The fuel flow may be preheated to a temperature below the autoignition temperature of the fuel flow, for example below 400°C, below 350°C, or below 300°C. For example, the fuel flow may be preheated from 100°C up to the autoignition temperature of the fuel flow, for example from 100°C to 400°C. In a preferred method of the present invention, the fuel flow is an ammonia-containing fuel flow and is supplied from a preheated ammonia flow.

[0056] The ratio of the pre-combustion fuel flow to the oxygen-containing off-gas flow in the fuel combustion zone can be suitably selected to enable efficient combustion of the fuel flow. The ratio of the pre-combustion fuel flow to the oxygen-containing off-gas flow in the fuel combustion zone may vary depending on the amount of oxygen present in the oxygen-containing off-gas flow. For example, if the fuel flow is pure ammonia and the oxygen-containing off-gas contains 13.2 mol% oxygen, the ratio of the pre-combustion fuel flow to the oxygen-containing off-gas flow in the fuel combustion zone can be selected to be in the range of 1:6 to 1:7, for example, 1:6.5.

[0057] Preferably, the thermal energy generated by combustion using an oxygen-containing off-gas stream in the fuel combustion zone provides up to 100% of the thermal energy required for the ammonia decomposition reactor to decompose ammonia in the ammonia stream, for example, up to 95%, 90%, 85%, or 80% of the thermal energy required for the ammonia decomposition reactor to decompose ammonia in the ammonia stream. Preferably, the thermal energy generated by combustion using an oxygen-containing off-gas stream in the fuel combustion zone provides more than 50% of the thermal energy required for the ammonia decomposition reactor to decompose ammonia in the ammonia stream, for example, more than 60%, 70%, or 75% of the thermal energy required for the ammonia decomposition reactor to decompose ammonia in the ammonia stream. For example, preferably, the thermal energy generated by combustion using an oxygen-containing off-gas stream in the fuel combustion zone provides more than 50% and up to 100% of the thermal energy required for the ammonia decomposition reactor.

[0058] Optionally, the method of the present invention may include a step of sending a portion of the oxygen-containing off-gas to a heat recovery zone, such as a heat recovery steam generator. If desired, unburned ammonia or nitrogen oxides in the oxygen-containing off-gas may be washed off or reacted off from the oxygen-containing gas before it is sent to the fuel combustion zone.

[0059] Combustion in the fuel combustion zone generates flue gas, which can be recovered from the ammonia decomposition reactor. The flue gas may be cooled in one or more cooling steps and subjected to one or more purification steps before being discharged into the atmosphere. One or more cooling steps may include a preheating step for one or more reactants for the ammonia decomposition reactor and / or a steam generation step. One or more purification steps may include a selective catalytic reduction (SCR) step in which nitrogen oxides react with ammonia to form nitrogen and water vapor. Any flue gas selective catalytic reduction technique can be used.

[0060] In a particular embodiment of the method of the present invention, the method is The process of supplying an ammonia stream to the ammonia decomposition reactor, A process of decomposing ammonia in an ammonia stream in an ammonia decomposition reactor to generate a hydrogen-containing stream, The process optionally involves supplying a hydrogen-containing flow to a purification unit such as a pressure swing absorption unit to increase the hydrogen content and generate a hydrogen-enriched flow and tail gas. Optionally, a step of supplying a hydrogen enrichment flow to a steam generation unit and / or a heat recovery zone, A process of combining a hydrogen-enriched flow with an oxygen-containing feed, burning the hydrogen-enriched flow together with the oxygen-containing feed, and generating a burnt gas flow. A process of using a combustion gas flow to drive a gas turbine and generate an oxygen-containing off-gas flow, A step of supplying at least a portion of the oxygen-containing off-gas flow to the fuel combustion zone, The process of optionally supplying an additional fuel source to the fuel combustion zone, The process includes burning a fuel flow and an optional additional fuel source together with an oxygen-containing off-gas flow in the fuel combustion zone to generate thermal energy for an ammonia decomposition reactor.

[0061] In a particular embodiment of the method of the present invention, the method is The process of supplying an ammonia stream to the ammonia decomposition reactor, A process of decomposing ammonia in an ammonia stream in an ammonia decomposition reactor to generate a hydrogen-containing stream, A process of supplying a hydrogen-containing flow to a purification unit such as a pressure swing absorption unit to increase the hydrogen content and generate a hydrogen-enriched flow and tail gas, Optionally, a step of supplying a hydrogen enrichment flow to a steam generation unit and / or a heat recovery zone, A process of combining a hydrogen-enriched flow with an oxygen-containing feed, burning the hydrogen-enriched flow together with the oxygen-containing feed, and generating a burnt gas flow. A process of using a combustion gas flow to drive a gas turbine and generate an oxygen-containing off-gas flow, A step of supplying at least a portion of the oxygen-containing off-gas flow to the fuel combustion zone, The process of optionally supplying an additional fuel source to the fuel combustion zone, The process of supplying tail gas to the fuel combustion zone, The process includes burning a fuel stream and tail gas, as well as an optional additional fuel source, together with an oxygen-containing off-gas stream in the fuel combustion zone to generate thermal energy for an ammonia decomposition reactor.

[0062] Figure 1 shows a block flow diagram of a method not according to the present invention, which includes a non-integrated gas turbine. The block flow diagram of Figure 1 shows the flow in which ammonia (1) is supplied to the ammonia preheating and vaporization zone (2) outside the ammonia decomposition reactor, and the ammonia is vaporized. The preheated and vaporized ammonia is supplied to the ammonia superheating zone (3) and the decomposition unit combustion zone (13). In the block flow diagram of Figure 1, the ammonia decomposition reactor (4), the ammonia superheating zone (3), and the decomposition unit combustion zone (13) are all part of the same single piece of equipment. Ammonia from the ammonia superheating zone (3) is supplied to the ammonia decomposition reactor (4), where a hydrogen-containing flow is generated. The hydrogen-containing flow is supplied to the steam generator (5) and the heat recovery zone (6). The hydrogen-containing flow from the heat recovery zone (6) is supplied to the gas turbine (7), where it is burned in the presence of an oxygen-containing feed, which is compressed air (17) by the compressor (8). Steam from the steam generator (5) and off-gas from the gas turbine (7) are used to generate electricity (10). Heat from the off-gas from the gas turbine (5) is recovered by a heat recovery steam generator (9). In the fuel combustion zone (13), ammonia fuel is combined with preheated air from the air preheating zone (12). The ammonia fuel and preheated air are burned in the fuel combustion zone (13) to generate thermal energy for the ammonia decomposition reactor (4). The exhaust gas from the ammonia decomposition reactor (4) is recovered in the heat recovery zone (14), and the exhaust gas is sent to the chimney (15) and discharged as flue gas (16). The heat from the heat recovery zone (14) is used in the ammonia preheating and vaporization zone (2) and the air preheating zone (12) (not shown for clarity). One or more process flows may be heated in exchange for exhaust gas in the heat recovery zone (14).

[0063] Figure 2 shows a block flow diagram of the method according to the present invention, which includes an integrated gas turbine. The block flow diagram in Figure 2 shows the flow in which ammonia (21) is supplied to the ammonia preheating and vaporization zone (22) outside the ammonia decomposition reactor, where the ammonia is vaporized. The preheated and vaporized ammonia is supplied to the ammonia superheating zone (23) and the fuel combustion zone (213). In the block flow diagram in Figure 2, the ammonia decomposition reactor (24), the ammonia superheating zone (23), and the fuel combustion zone (213) are all part of the same single piece of equipment. Ammonia from the ammonia superheating zone (23) is supplied to the ammonia decomposition reactor (24), where it generates a hydrogen-containing flow. The hydrogen-containing flow is supplied to the steam generator (25) and the heat recovery zone (26). The hydrogen-containing flow from the heat recovery zone (26) is supplied to the gas turbine (27), where it is burned in the presence of an oxygen-containing feed, which is compressed air (217) by the compressor (28). A portion of the steam from the steam generator (25) and the off-gas from the gas turbine (27) is used to generate electricity (210). A portion of the heat from the off-gas from the gas turbine (25) is recovered by a heat recovery steam generator (29). In the fuel combustion zone (213), ammonia fuel is combined with a portion of the oxygen-containing off-gas from the gas turbine (27). The ammonia fuel and oxygen-containing off-gas are burned in the fuel combustion zone (213) to generate thermal energy for the ammonia decomposition reactor (24). The exhaust gas from the ammonia decomposition reactor (24) is recovered in the heat recovery zone (214), and the exhaust gas is sent to the chimney (215) and discharged as flue gas (216). The heat from the heat recovery zone (214) is used in the ammonia preheating and vaporization zone (22) (not shown for clarity). [Examples]

[0064] To demonstrate the efficiency savings achieved by the method of the present invention, a simulation was conducted comparing a flow sheet with a non-integrated gas turbine (not according to the present invention) as shown in Figure 1 and a flow sheet with an integrated gas turbine (according to the present invention) as shown in Figure 2.

[0065] The following assumptions were made for both flow sheets: ●The same ammonia decomposition reactor and gas turbine were used for both flowsheets. ● The energy requirements of the ammonia decomposition reactor were met by the combustion of ammonia, and the total amount of ammonia available to the entire system was set at 1200 metric tons / day (MTPD). ●The ammonia temperature at the inlet to the decomposition device was 600°C. ● The ammonia temperature at the inlet to the combustion side of the decomposition unit was 90°C. ●The ambient temperature was 10℃. ●The fuel requirements were set to achieve a 0.58% ammonia slip on both flow sheets. ●The flue gas from the HRSG was set to 280°C, and the HPS was increased within the HRSG.

[0066] [Table 1] *Total energy in the entire ammonia flow, assuming a LHV of ammonia is 316,449.8 kJ / kmol. **The energy requirements of rotating machinery (excluding air compressors) and the energy generated from steam production through heat recovery of decomposition gases were not included in this analysis.** In integrated systems, the energy generated is higher than in non-integrated systems due to the higher outlet temperature and flow rate of the decomposition gases.

[0067] ***Based on the following formula:

[0068]

number

[0069] The above simulation demonstrates that a system equipped with an integrated gas turbine according to the present invention is more energy-efficient and generates more power per unit of ammonia supplied to the system compared to a non-integrated gas turbine.

Claims

1. A method for generating electricity using a gas turbine that uses a carbon-free fuel obtained from the catalytic decomposition of ammonia, The process of supplying an ammonia stream to the ammonia decomposition reactor, The process involves decomposing the ammonia in the ammonia stream within the ammonia decomposition reactor to generate a hydrogen-containing stream, A step of combining the hydrogen-containing flow with an oxygen-containing feed, burning the hydrogen-containing flow together with the oxygen-containing feed to generate a burnt gas flow, The process involves using the aforementioned combustion gas flow to drive a gas turbine and generate an oxygen-containing off-gas flow, A step of supplying at least a portion of the oxygen-containing off-gas flow to the fuel combustion zone, The process includes burning a fuel stream and an oxygen-containing off-gas stream within the fuel combustion zone to generate thermal energy for the ammonia decomposition reactor, The fuel combustion zone is the radiating section within the box-shaped furnace of the ammonia decomposition reactor, in this method.

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

3. The method according to claim 1 or 2, wherein the temperature of the ammonia stream at the inlet of the ammonia decomposition reactor is within the range of 350°C to 1000°C, 400°C to 950°C, 450°C to 850°C, or 500°C to 750°C.

4. The method according to claim 1, wherein the hydrogen-containing stream contains 40 mol% to 75 mol% hydrogen.

5. The method according to claim 1, further comprising the step of supplying the hydrogen-containing stream to a purification unit to increase the hydrogen content of the hydrogen-containing stream and generate a hydrogen-enriched stream and a tail gas.

6. The method according to claim 5, wherein the hydrogen-enriched flow contains 50 mol% to 100 mol% hydrogen.

7. The method according to claim 1, wherein the oxygen-containing feed is a compressed oxygen-containing feed.

8. The method according to claim 1, wherein the oxygen-containing supply is air, oxygen, or oxygen-enriched air.

9. The method according to claim 1, wherein the oxygen-containing off-gas stream may contain an amount of oxygen ranging from 5 mol% to more than 25 mol%.

10. The method according to claim 1, wherein the oxygen-containing off-gas flow is 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.

11. The method according to claim 1, wherein the portion of the oxygen-containing off-gas flow supplied to the fuel combustion zone is 5% to 75%, 7% to 50%, 8% to 30%, or 9% to 20% of the total oxygen-containing off-gas flow leaving the gas turbine.

12. The method according to claim 1, wherein the fuel flow contains ammonia.

13. The method according to claim 1, wherein the fuel flow contains ammonia in an amount of 1 mol% to 100 mol%, preferably 5 mol% to 75 mol%, 10 mol% to 50 mol%, or 15 mol% to 30 mol% of the total fuel flow.

14. The method according to claim 5, comprising the steps of supplying the tail gas to the fuel combustion zone and burning the fuel flow and the tail gas together with the oxygen-containing off-gas flow.

15. The method according to claim 5, wherein the fuel stream includes hydrogen, natural gas, methane, refinery off-gas, biogas, the tail gas from the refining unit, and a portion of the hydrogen-containing stream from the ammonia decomposition reactor, one or more additional fuel sources.

16. The method according to claim 12, wherein the fuel flow contains ammonia, and the ammonia-containing fuel flow is supplied from the same source as the ammonia flow supplied to the ammonia decomposition reactor.

17. The method according to claim 1, wherein the thermal energy generated by combustion using the oxygen-containing off-gas flow in the fuel combustion zone provides more than 50% and up to 100% of the thermal energy required for the ammonia decomposition reactor.

18. A method for modifying an ammonia production facility, comprising the step of carrying out the method according to claim 1 in the ammonia production facility.

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