Method and device for generating electrical control energy

Abstract

The invention relates to a method and to a device for generating electrical control energy (8) for a power network, wherein a fuel (7) is combusted in a gas turbine (T), which drives an electrical generator (G) which is connected to a power network, and which provides the control energy (8) The invention is characterised in that ammonia (1) is thermally cracked with catalytic support in order to obtain a cracked gas (4) comprising hydrogen and nitrogen, of which at least part (7) is supplied as fuel to the gas turbine (T) if necessary, wherein cracked gas (9) not required for operating the gas turbine (T) is further processed to form a hydrogen product (10).

Description

[0001] October 8, 2025 - Werner Fischer

[0002] 1

[0003] Description

[0004] Method and device for generating electrical control energy

[0005] The invention relates to a method for generating electrical control energy for a power grid, wherein ammonia is split into hydrogen and nitrogen to obtain fuel for a gas turbine that drives an electric generator connected to the power grid, which provides the control energy.

[0006] Furthermore, the invention relates to a device for carrying out the method according to the invention.

[0007] When generating electricity for a power grid that connects numerous consumers to one or more electricity providers, it is crucial to ensure that electricity supply and demand are balanced. Otherwise, voltage and frequency fluctuations, or even a grid outage, can occur. Generally, consumer demand in a public power grid is not constant over time. For example, it is approximately three times higher during the day than at night. It is also higher on weekdays than on weekends and in winter than in summer. Electricity providers attempt to balance these differences between supply and demand by switching power plants on and off, or by adjusting their output.For baseload power plants like coal-fired power plants, this is inefficient because their efficiency drops drastically during partial load operation. Furthermore, due to thermal inertia, the faster and more unexpectedly such fluctuations occur, the more difficult this becomes. The increased use of renewable energies for electricity generation will exacerbate this problem in the future, as solar and wind power, in particular, are not consistently available over time, and their availability is only partially predictable in the long term.

[0008] Electricity deficits are balanced with so-called balancing power, which is provided by peak load power plants such as gas-fired or combined cycle gas turbine (CCGT) power plants, in which a gas turbine alone or together with a downstream steam turbine drives an electric generator. (October 8, 2025 - Werner Fischer)

[0009] With their very short start-up times and high electrical efficiencies, which can exceed 50%, gas and combined cycle power plants are particularly well suited for such applications.

[0010] Both gas-fired and combined cycle gas turbine (CCGT) power plants are usually fueled with natural gas, which produces carbon dioxide during their operation. This carbon dioxide must be disposed of through costly sequestration processes to prevent its release into the atmosphere, which would have negative consequences for the climate. The carbon dioxide problem could be mitigated by using green or blue ammonia—produced without carbon dioxide emissions—as fuel instead of natural gas. However, the use of pure ammonia is highly problematic due to its toxicity, low flame speed, nitrogen oxide formation, and the stringent requirements for turbine materials.

[0011] To circumvent this problem, EP4372218A1 proposes to thermally split ammonia into hydrogen and nitrogen with catalytic assistance, to separate the resulting cracked gas into a hydrogen and a nitrogen fraction with considerable effort, and to supply either the hydrogen fraction alone or together with the nitrogen fraction, which may also contain unreacted ammonia, to a gas turbine as fuel.

[0012] The object of the present invention is to provide a method and a device of the generic type which makes it possible to overcome the disadvantages of the prior art.

[0013] The problem is solved according to the invention by thermally splitting ammonia with catalytic support to obtain a cracked gas comprising hydrogen and nitrogen, at least part of which is supplied to the gas turbine as fuel when required, wherein cracked gas not required for the operation of the gas turbine is further processed into a hydrogen product.

[0014] The need arises when balancing power is required for the electricity grid and no other fuel suitable for operating the gas turbine is available, available in insufficient quantities, or not intended for use. October 8, 2025 - Werner Fischer

[0015] 3

[0016] Preferably, the cracking gas is produced in a quantity sufficient to cover the maximum fuel requirement of the gas turbine, so that the gas turbine can be operated with cracking gas as fuel even at full load.

[0017] The splitting of ammonia is well-known and has been state of the art for many years. The reaction, which occurs with catalytic assistance,

[0018] The reaction 2NH3 ⇌ N2 + 3H2 is endothermic (AH = 46.2 kJ / mol). The position of the equilibrium and the reaction rate depend strongly on the cracking pressure and temperature, as well as on the type of catalyst used, so that the resulting cracking gas contains unreacted ammonia in addition to hydrogen and nitrogen. Furthermore, the cracking gas may also contain water, which is present in so-called technical-grade ammonia, as commonly used for industrial ammonia cracking, at a concentration of up to 5000 ppm by weight and does not participate in the cracking reaction.

[0019] To allow the hydrogen produced and contained in the cracking gas to be released as a product with little or no compression, ammonia cracking is expediently carried out at pressures between 10 and 40 bar. This is made easier because ammonia is usually supplied in liquid form for cracking, allowing its pressure to be increased with minimal energy expenditure using a pump. To achieve a sufficiently high and economically viable conversion rate of the ammonia used under these conditions, it is necessary to operate the cracking process at temperatures between 500 and 1000°C.

[0020] Because of its high proportions of hydrogen and nitrogen, which acts as a temperature moderator and increases the mass flow, the cracked gas is suitable for use as fuel in a commercially available gas turbine designed for operation with natural gas, with the help of which the balancing energy can be generated without releasing carbon dioxide into the atmosphere, provided that the ammonia used for cracking is green ammonia.

[0021] Electrically heated fission reactors can be used to crack ammonia, which is particularly suitable for industrial applications with comparatively low energy consumption. 08.10.2025 - Werner Fischer

[0022] 4

[0023] Hydrogen demand of less than 1000m n 3 / h, for example, is economically advantageous for the heat treatment of metals. In principle, the hydrogen and nitrogen-containing cracking gas can be provided without the release of carbon dioxide if the required electricity is obtained from renewable sources.

[0024] Ammonia can be cracked at higher rates using reactors similar to those currently employed in large-scale synthesis gas production through the steam reforming of hydrocarbons. Such plants comprise a cracking reactor with a combustion chamber containing cracking tubes filled with catalyst material, and a waste heat recovery system. The combustion chamber is heated by one or more burners, which supply the energy for the endothermic cracking of the ammonia passing through the cracking tubes.

[0025] Upstream of an allothermal fission reactor heated electrically or via burners, an adiabatic pre-fission reactor can be arranged, which uses only the energy of the feedstock supplied to it to fission a large portion of the ammonia it contains. The content of unreacted ammonia in the resulting fission gas (pre-fission gas) is significantly higher than in the fission gas (full fission gas) obtained in the subsequent allothermal fission reactor.

[0026] Advantageously, it is not necessary to process the cracked gas, which can be either pre- or full-firing gas, into fuel for the gas turbine by separating components. However, it may be necessary to cool at least the portion of the cracked gas intended as fuel so that it does not exceed the permissible inlet temperature of the gas turbine, which is typically around 350°C. It is expedient to actively reduce the pressure of the cracked gas on its way to the gas turbine, i.e., not more than is necessary due to unavoidable line losses, since, in addition to the chemical energy, the pressure energy of the nitrogen contained in the fuel can also be converted into balancing energy.

[0027] A preferred embodiment of the inventive method provides for carrying out the ammonia cracking in a single cracking step and for using at least a portion of the cracked gas (full cracked gas) obtained in the gas turbine if required. 08.10.2025 - Werner Fischer

[0028] 5. to be supplied as fuel. Fully cracked gas not required for operating the gas turbine is processed into a hydrogen product by separating nitrogen, ammonia and, if necessary, water, which can be released at the plant boundary against a credit note.

[0029] In another embodiment of the process according to the invention, the ammonia cracking is carried out in a preferably adiabatic pre-crack step and a subsequent main cracking step, wherein at least a portion of the cracking gas obtained in the pre-crack step (pre-crack gas) and / or at least a portion of the fully cracked gas obtained in the main cracking step is supplied to the gas turbine as fuel if required. If a portion of the pre-crack gas is supplied to the gas turbine, the remaining portion of this gas is further processed in the main cracking step, and at least a portion of the fully cracked gas thus obtained is purified to a hydrogen product by separating nitrogen, ammonia, and optionally water.

[0030] The use according to the invention of cracked gas not required for the generation of balancing energy for the production of a hydrogen product makes it possible to crack a constant flow of ammonia, so that the entire ammonia cracking, or at least a pre-cracking step, can always be carried out under optimal operating conditions, regardless of the amount of fuel required for the gas turbine.

[0031] To cool the cracked gas to the gas turbine inlet temperature, it is preferably used for vaporizing and / or superheating the liquid ammonia feedstock. Cooling can be omitted if the cracked gas intended as fuel for the gas turbine is already obtained at a suitable temperature for the gas turbine inlet in an adiabatic pre-fission step.

[0032] If the pre-fission gas obtained in a pre-fission step is fed wholly or partially to the gas turbine, it is possible that insufficiently hot fission gas will be obtained in the main fission step for complete vaporization or superheating of the ammonia feed. In this case, in particular, it may be advantageous to use the method described in the 08.10.2025 - Werner Fischer

[0033] 6

[0034] to return the exhaust gas received from the gas turbine and to cool it against the ammonia input that is to evaporate and / or overheat.

[0035] Preferably, nitrogen, ammonia, and optionally water are separated from the fully cracked gas not required for the gas turbine by pressure swing adsorption, producing a residual gas containing hydrogen, ammonia, and optionally water in addition to the hydrogen product. This residual gas is expediently combusted to generate the heat required for ammonia cracking. It is also possible to export at least a portion of the residual gas or dispose of it in a flare.

[0036] If the residual gas obtained by pressure swing adsorption is too small to cover the heat requirement of ammonia cracking, it is planned to divert a portion of the fully cracked gas upstream of the pressure swing adsorption and burn it to obtain heat for ammonia cracking.

[0037] The device for generating electrical control energy for a power grid, which is also included in the invention, has a gas turbine that is coupled to a generator and can be connected to the power grid via the generator, as well as a fuel supply through which fuel required for its operation can be supplied to the gas turbine.

[0038] According to the invention, the device achieves the stated objective by having a separation device and a cracking device connected to the gas turbine and the separation device, in which ammonia can be thermally cracked with catalytic assistance to obtain a cracked gas comprising hydrogen and nitrogen, at least part of which can be supplied to the gas turbine as fuel via the fuel supply if required, while cracked gas not required for the operation of the gas turbine can be processed into a feed gas from which a hydrogen product can be separated in the separation device.

[0039] In one embodiment, the cracking device of the invention comprises exactly one cracking reactor, which is connected to the gas turbine via the fuel supply on the outlet side, so that cracking gas obtainable in the cracking reactor can be supplied to the gas turbine via the fuel supply. 08.10.2025 - Werner Fischer

[0040] 7

[0041] In another embodiment, the cracking device of the device according to the invention has a pre-fiscation reactor, preferably designed for adiabatic operation, and a main cracking reactor downstream thereof, at least one of which is connected to the gas turbine on the outlet side, so that cracking gas obtainable in the pre-fiscation reactor and / or in the main cracking reactor can be supplied to the gas turbine via the fuel supply.

[0042] To generate the heat required for ammonia cracking, the cracking unit can be equipped with one or more burners and / or an electric heating element. If the cracking unit comprises a pre-fission reactor and a main cracking reactor arranged in series with it, preferably at least the main cracking reactor is equipped with an electric heating element.

[0043] The separation device arranged downstream of the cracking unit preferably comprises a pressure swing adsorber with which nitrogen, ammonia, and optionally water can be separated from the cracking gas, which has been processed into a feed gas, for example by cooling, in order to obtain the hydrogen product as well as a residual gas containing hydrogen, nitrogen, ammonia, and optionally water. The pressure swing adsorber can be connected to the cracking unit so that at least part of the residual gas can be recycled for combustion to provide heat for ammonia cracking.

[0044] Ideally, the gas turbine is connected to the cracking device on the outlet side, so that the heat from the gas turbine exhaust gas can be used to vaporize and / or superheat the ammonia used in the cracking device.

[0045] The invention will now be explained in more detail with reference to two exemplary embodiments schematically illustrated in Figures 1 and 2. In both figures, identical plant components and material flows are marked with the same reference numerals.

[0046] Figure 1 shows a preferred embodiment of the invention with exactly one fission reactor, while Figure 2 shows another embodiment of the invention with a pre-fission reactor and a main fission reactor. 08.10.2025 - Werner Fischer

[0047] 8

[0048] Liquid technical-grade ammonia 1 is extracted from tank A by pump P and fed to evaporator V at a pressure between 10 and 50 bar to obtain saturated ammonia steam 2. This steam is heated to approximately 550°C in superheater S before being routed via line 3 to the cracking unit C, which consists of a burner-fired cracking reactor. With the further input of heat and catalytic assistance, the superheated ammonia 3 is cracked in the cracking unit C, producing cracking gas 4, consisting largely of hydrogen and nitrogen, which contains unreacted ammonia and water. This gas leaves the cracking unit C at a temperature of up to approximately 900°C.In the superheated S, the hot cracking gas 4 is cooled against the ammonia saturated steam 2 to be superheated, obtaining a cracking gas 5 cooled to a first temperature, which is further cooled in the evaporator V against the ammonia feed 1 to be evaporated to a second temperature, which allows the cracking gas 6 to be used as fuel in the gas turbine T.

[0049] If required, at least part 7 of the cooled cracking gas 6 is combusted in the gas turbine T, which generates electricity 8 via the coupled generator G. This electricity is fed into a power grid (not shown) as balancing power. The part 9 of the cooled cracking gas 6 not required for use in the gas turbine T is fed – after any further cooling that may be necessary – to the separation unit R, where it is separated, for example by pressure swing adsorption, into a hydrogen product 10 and a residual gas 11, which contains hydrogen and ammonia in addition to nitrogen and water. While the hydrogen product 10 is released against credit, the residual gas 11 is returned to the cracking reactor C, which is constructed similarly to a steam reformer, and combusted to provide heat for ammonia cracking. Carbon dioxide-free exhaust gas 12, which cools the gas turbine T at a temperature of up to approximately...Leaving at 500°C, it is cooled in the superheater S against the ammonia vapor 3 to be superheated, obtaining an exhaust gas 13 cooled to a first temperature, which, after further cooling in the evaporator V against the ammonia feedstock 1 to be evaporated, is released into the atmosphere via line 14.

[0050] In the embodiment shown in Figure 2, the superheated ammonia vapor 3 is fed into a cracking unit C', which comprises an adiabatically operated pre-crack reactor B and an electrically heated main cracking reactor E. In the pre-crack reactor B, a 08.10.2025 - Werner Fischer

[0051] 9

[0052] Part of the ammonia contained in the ammonia vapor 3 is split with catalytic assistance and using sensible heat into hydrogen and nitrogen, producing the pre-splitting gas 15, whose composition and temperature allow its use as fuel in the gas turbine T.

[0053] If required, at least part 16 of the pre-fission gas 15 is combusted in the gas turbine T, which generates electricity 8 via the coupled generator G. This electricity is fed into a power grid (not shown) as balancing power. The part 17 of the pre-fission gas 15 not required for use in the gas turbine T is fed into the main fission reactor E, where the majority of the ammonia it contains is split into hydrogen and nitrogen with the addition of heat and catalytic assistance. This produces a fully cracked gas 4, consisting largely of hydrogen and nitrogen, unreacted ammonia, and water, which leaves the cracking unit C' at a temperature of up to approximately 900°C.In the superheated chamber S, the hot fully cracked gas 4 is cooled against the ammonia saturated steam 2 to be superheated, yielding a fully cracked gas 5 cooled to a first temperature. This gas is then further cooled to a second temperature in the evaporator V against the ammonia feedstock 1 to be evaporated and subsequently fed via line 9 to the separation unit R. There, it is separated, for example by pressure swing adsorption, into a hydrogen product 10 and a residual gas 11, which contains hydrogen and ammonia in addition to nitrogen and water. While the hydrogen product 10 is released against credit, the residual gas 11 is fed to an external consumer or a flare (neither of which are shown).

Claims

October 8, 2025 - Werner Fischer 10 Patent claims 1. Method for generating electrical control energy (8) for a power grid, wherein a fuel (7, 16) is burned in a gas turbine (T) which drives an electric generator (G) connected to the power grid, which provides the control energy (8), characterized in that ammonia (1) is thermally cracked with catalytic assistance to obtain a cracked gas (4, 15) comprising hydrogen and nitrogen, at least a part (7, 16) of which is supplied to the gas turbine (T) as fuel when required, wherein cracked gas (9, 17) not required for the operation of the gas turbine (T) is further processed to a hydrogen product (10).

2. Method according to claim 1, characterized in that the ammonia cracking is carried out in a single cracking step (C) and at least a part (7) of the cracked gas (4) obtained is supplied to the gas turbine (T) as fuel.

3. Method according to claim 1, characterized in that the ammonia cracking is carried out in a pre-crack (B) and a main cracking step (E), wherein at least a part (16) of the cracking gas (15) obtained in the pre-crack step (B) is supplied to the gas turbine (T) as fuel.

4. Method according to claim 3, characterized in that at least a part of the cracking gas (4) obtained in the main cracking step (E) is supplied to the gas turbine (T) as fuel.

5. Method according to one of claims 1 to 4, characterized in that the cracked gas (7, 16) is supplied to the gas turbine (T) as fuel without active pressure reduction.

6. Method according to one of claims 1 to 5, characterized in that cracked gas (9, 17) not required for the operation of the gas turbine (T) is processed to a hydrogen product (10) by the main cracking step (E) and / or the separation of nitrogen, ammonia and, if applicable, water (R).

7. Method according to any one of claims 1 to 6, characterized in that the portion of the cracked gas (9) not required for the operation of the gas turbine (T) is processed by pressure swing adsorption to form a residual gas (11), from October 8, 2025 - Werner Fischer 11, at least part of which is burned to provide heat for ammonia cracking.

8. Method according to one of claims 1 to 7, characterized in that the heat required for ammonia cracking is generated electrically.

9. Method according to one of claims 1 to 8, characterized in that the heat from the exhaust gas generated in the gas turbine (T) is used for the evaporation (V) and / or superheating (S) of the ammonia (1) used for cracking.

10. Device for generating electrical control energy (8) for a power grid, comprising a gas turbine (T) coupled to a generator (G) and connected to the power grid via the generator, and a fuel supply through which fuel (7, 16) required for the operation of the gas turbine (T) can be supplied, characterized in that it has a separation device (R) and a cracking device (C, C') connected to the gas turbine (T) and the separation device (R), and in which ammonia (1) can be thermally cracked with catalytic assistance to obtain a cracked gas (4, 15) comprising hydrogen and nitrogen, at least a part (7, 16) of which can be supplied to the gas turbine (T) as fuel via the fuel supply (7, 16) when required, while cracked gas (9, 16) not required for the operation of the gas turbine (T) can be processed into a feed gas, of which in the Separation device (R) a hydrogen product (10) can be separated.

11. Device according to claim 10, characterized in that the cracking device (C) has exactly one cracking reactor which is connected to the gas turbine (T) via the fuel supply on the outlet side, so that cracking gas (4) obtainable in the cracking reactor (C) can be supplied to the gas turbine (T) as fuel (7) via the fuel supply.

12. Device according to claim 10, characterized in that the cracking device (C') comprises a pre-fiscation reactor (B) and a main cracking reactor (E) downstream thereof, at least one of which is connected to the gas turbine (T) on the outlet side, so that cracking gas (15) obtainable in the pre-fiscation reactor (B) and / or in the main cracking reactor (E) can be supplied as fuel (16) via the fuel supply of the gas turbine (T). October 8, 2025 - Werner Fischer 12 13. Device according to one of claims 10 to 12, characterized in that the separation device (R) arranged downstream of the cracking device (C, C') has a pressure swing adsorber with which nitrogen, ammonia and optionally water can be separated from a feed gas (9) obtainable from cracking gas in order to obtain the hydrogen product (10) and a residual gas (11) containing hydrogen, nitrogen, ammonia and optionally water.

14. Device according to one of claims 10 to 13, characterized in that the gap device (C, C') can be heated by an electrical heating device.

15. Device according to one of claims 10 to 14, characterized in that the gas turbine (T) is connected on the outlet side to a device for evaporating (V) and / or superheating (S) the ammonia (1) that can be used in the cracking device (C, C'), so that heat from exhaust gas (12) generated in the gas turbine can be used for evaporating and / or superheating the ammonia (1) that can be used in the cracking device (C, C').

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