Catalytic decomposition of ammonia with water vapour as heat transfer medium

Abstract

The invention relates to a system and a method for preparing H2 by catalytically decomposing NH3. Water is used as the heat transfer medium to recover process heat. The process heat is received by water or water vapour and is then discharged to NH3, as a result of which NH3 is heated and evaporated. Using water or water vapour as the heat transfer medium offers advantages inter alia with regard to economy and safety.

Description

Catalytic decomposition of ammonia using steam as heat transfer medium

[0001] Priority is claimed from Luxembourg patent application No. LU 103144 of 6 June 2023.

[0002] The invention relates to a plant and a method for producing H2 by catalytic decomposition of NH3. Water serves as the heat transfer medium for recovering process heat. The process heat is absorbed by water or steam and then transferred to NH3, heating and evaporating the NH3. The use of water or steam as the heat transfer medium has advantages, including cost-effectiveness and safety.

[0003] H2 can be extracted from H2O using renewable energy and then converted into NH3 with N2. NH3 can be stored and transported much more safely than H2. NH3 can then be decomposed back into H2 and N2. After N2 is separated, H2 finds a wide variety of industrial applications.

[0004] The decomposition of NH3 to N2 and H2 is an endothermic reaction (AH° = 45.9 kJ-mol 1 ), in which the amount of substance doubles (2 NH3 N2 + 3 H2), so the reaction is generally favored by high temperatures and low pressures. The higher the pressure, the higher the temperature must be to achieve satisfactory reaction yields. A variety of materials have been proposed as catalysts for the decomposition of NH3, which are active at different temperatures (see, for example, II. Lucentini et al., Ind. Eng. Chem. Res. 2021, 60, 18560-18611).

[0005] The catalytic decomposition of NH3 produces a product gas that contains H2 mixed with N2 and possibly other gaseous components, e.g., undecomposed NH3. However, many industrial applications require H2 of high purity, so the product gas must be purified before it can be used in industrial applications. While the purification of H2 is generally possible using various processes, e.g., cryogenic processes or membrane processes, purification by pressure swing adsorption is particularly economical on an industrial scale.

[0006] The catalytic decomposition of NH3 into N2 and H2 occurs at high temperatures and moderate pressure in the gas phase. NH3 is stored in liquid form in cooled tanks at atmospheric pressure and -32.8°C. NH3 is fed into the plant by a pump at system pressure. Due to the increased system pressure, the boiling point of the NH3 rises, for example, to approximately 62.2°C at 27.8 bar a. To convert NH3 into the gas phase, heat is required to evaporate the NH3.

[0007] Conventional processes for the catalytic decomposition of NH3 generate significant amounts of heat, which can be used to evaporate NH3.

[0008] US 4,704,267 A concerns the production of high-purity H2 from liquid, anhydrous NH3. NH3 is vaporized and then separated into its components. The resulting dissociated gas stream is fed to an adiabatic metal hydride purification unit to absorb the H2 present in the stream. The adsorbed H2 is then recovered as a high-purity product.

[0009] US 2022 / 170433 A1 relates to a reforming system comprising an evaporator configured to evaporate liquid fuel to produce fuel gas; a reformer configured to reform the fuel gas produced by the evaporator to produce a reformed gas containing hydrogen; an air supplier configured to supply air to the reformer; a fuel gas supplier configured to supply the fuel gas to the reformer; a heater configured to increase a temperature of the reformer; a reformed gas flow passage through which the reformed gas produced by the reformer flows; a cooler arranged in the reformed gas flow passage and configured to cool the reformed gas; a circulation passage connecting the evaporator to the cooler and through which refrigerant flows through the evaporator and the cooler.and a circulation pump disposed in the circulation passage and configured to circulate the refrigerant through the circulation passage;

[0010] EP 4 067 298 A1 relates to a method for refueling vehicle tanks with compressed hydrogen, which comprises splitting ammonia into hydrogen and nitrogen in an ammonia cracking plant, compressing the hydrogen from the ammonia cracking plant and delivering the compressed hydrogen to the vehicle tanks in a hydrogen refueling plant having one or more delivery units, wherein cooled ammonia is used to cool the compressed hydrogen before delivery to the vehicle tanks by heat exchange between the compressed hydrogen and the cooled ammonia so that the cooled ammonia is heated, and the heated ammonia is transferred to the ammonia cracking unit.

[0011] FR 1 469 045 A relates to an apparatus comprising a preheater fed with NH3, a tube bundle enclosing a catalyst for splitting NH3 and, optionally, a cell for purifying H2 by diffusion, which are interconnected and located in a single housing containing heating means.

[0012] CN 111 957 270 A relates to an NH3 decomposition device comprising an NF3 decomposition unit and a combustion unit acting on the NH3 decomposition unit. NH3 enters the NF3 decomposition unit via a first purified gas inlet to perform a decomposition reaction of the NH3. Produced mixed gas is discharged via a second purified gas outlet and then enters the combustion unit via a second purified gas inlet. The mixed gas comprises N2, H2, and undecomposed NH3. The mixed gas enters the combustion unit to provide heat for the NH3 decomposition reaction of the N2 decomposition unit, thus achieving heat self-sufficiency in the NH3 decomposition-H2 production system. No additional fuel is required for energy supply, and the cost of the NH3 decomposition-H2 production system is reduced.

[0013] CN 113 896 168 A relates to a process for producing H2 or reducing gas by cracking NH3 using a two-stage process comprising the following steps: The liquid NH3 of the raw material is fully gasified and heated by a heat-exchange gasification system and then enters a first-stage heat-exchange NH3 cracking reaction system to generate a partial NH3 cracking reaction. The reaction gas from the first-stage heat-exchange NfE cracking reaction system enters a second-stage high-temperature NH3 cracking reaction system to generate a residual NH3 cracking reaction. The second-stage high-temperature NH3 cracking reaction gas enters the first-stage heat-based NPh cracking reaction system and the heat exchange gasification system sequentially to gradually recover heat, so that the reducing gas is obtained.

[0014] WO 2001 / 087770 Al relates to the autothermal decomposition of NH3 to produce high-purity H2.

[0015] WO 2011 / 107279 A1 relates to an NH3-based H2 production reactor comprising an NFh cracking chamber with an NFh cracking catalyst, an inner combustion chamber with a combustion or oxidation catalyst in thermal contact with the NFh cracking chamber, an NFh gas preheating chamber, and an outer shroud for heat recovery from the combustion products exiting the combustion chamber, wherein the cracking chamber, the inner combustion chamber, the preheating chamber, and the heat recovery shroud are arranged concentrically.

[0016] WO 2017 / 160154 A1 relates to a method for power generation using a gas turbine, comprising the following steps: (i) evaporating and preheating liquid NH3 to produce preheated NH3 gas; (ii) introducing the preheated NH3 gas into an NH3 cracking device suitable for converting NH3 gas into a mixture of H2 and N2; (iii) converting the preheated NH3 gas into a mixture of H2 and N2 in the device; (iv) cooling the mixture of H2 and N2 to obtain a cooled H2 and N2 mixture; (v) introducing the cooled H2 and N2 mixture into a gas turbine; and (vi) combusting the cooled H2 and N2 mixture in the gas turbine to generate power.

[0017] WO 2019 / 038251 A1 relates to a process for producing a product gas containing N2 and H2 from NH3, comprising the steps of non-catalytic partial oxidation of NH3 with an O2-containing gas to a process gas containing N2, water, amounts of nitrogen oxides and residual amounts of NH; cracking at least a portion of the residual amounts of NH3 to H2 and N2 in the process gas by contact with a nickel-containing catalyst and simultaneously reducing the amounts of nitrogen oxides to N2 and water by reaction with a portion of the H2 formed during cracking of the process gas by contact of the process gas with the nickel-containing catalyst; and withdrawing the product gas containing H2 and N2.

[0018] WO 2012 / 039183 A1 relates to an NH3 decomposition device that produces H2 as a combustion enhancer and an NH3 oxidation device that reacts a portion of the introduced NH3 with O2 using an oxidation catalyst, causing combustion to provide the heat required for an NH3 decomposition reaction.

[0019] WO 2012 / 090739 A1 relates to a Th generator comprising a decomposition device that decomposes a compound containing an H atom and an N atom and generates H2; a compound supply device that supplies the compound to the decomposition device; and an O2 supply device that supplies O2 to the decomposition device.

[0020] WO 2020 / 095467 A relates to an apparatus for generating fP gas comprising: an NH3 evaporator that heats liquid NH3 to generate NfE gas; a main thermal decomposition device that causes combustion of a fuel gas, thereby heating and decomposing the NfE gas generated by the NH3 evaporator into N2 gas and H2 gas; a cooler that cools a decomposition gas containing the N2 gas and the H2 gas generated by the decomposition by the main thermal decomposition device; and a separator that separates the H2 gas from the cooled decomposition gas.

[0021] WO 2021 / 257944 A1 relates to the recovery of H2 from an NH3 cracking process in which the cracked gas is purified in a PSA device. The use of a membrane separator for the PSA off-gas improves the recovery.

[0022] WO 2022 / 096529 A1 relates to a process for cracking NH3, producing H2 and generating electric power, comprising electrolysis of water in supplied NH3, evaporation, preheating and cracking of NH3 using NfE-synthcsc catalysts at low temperatures.

[0023] WO 2022 / 243410 A1 relates to a process for the synthesis of H2 via the catalytic cracking of NH3; wherein an NfE-containing stream is subjected to a catalytic cracking step in the presence of heat to obtain a combusted gas and a thermally cracked stream containing N2, H2 and possibly residual NH3 and optionally water; wherein the thermally cracked stream is subjected to an H2 recovery step to obtain a high-purity H2 stream.

[0024] WO 2022 / 265647 A1 relates to the recovery of a renewable H2 product from an NH3 cracking process, in which the cracked gas is purified in a first PSA device and at least a portion of the first PSA tail gas is recycled as fuel to reduce the carbon intensity of the renewable energy product.

[0025] WO 2022 / 265648 A1 relates to the removal of NOx contaminants by selective catalytic reduction (SCR) from a flue gas produced in an NH3 cracking process, using an aqueous NHs solution produced by cooling the compressed exhaust gas from an H2 PSA device for cleaning the cracked gas.

[0026] WO 2022 / 265649 A1 concerns the reduction of the water content of the NH3 used in an NFF cracking process, thereby enabling the use of water-incompatible cracking catalysts. The water removal process can also be used to recover and recycle NH3 from the cracking gas.

[0027] WO 2022 / 265650 A1 relates to a NEE fission process in which fission gas is purified in a PSA system. Residual NH3 in a first fission gas is converted into further H2 and N2 by feeding PSA residual gas or a gas derived therefrom to a secondary fission reactor and further processing a second fission gas.

[0028] WO 2022 / 265651 A1 relates to a process in which residual NH3 is removed from NH3 cracking gas in an EE-PSA system using a non-zeolitic adsorbent such as activated carbon, activated alumina or silica gel.

[0029] WO 2023 / 144335 A1 relates to a process for producing hydrogen by splitting ammonia, in which ammonia is split into hydrogen and nitrogen in the presence of a catalyst, wherein the splitting of the ammonia takes place without prior non-catalytic oxidation in the absence of an oxidizing agent only by supplying heat in the presence of the catalyst. According to one of several alternative possible process variants, the splitting of the ammonia is carried out in a reactor (18) analogous to a primary reformer, wherein the catalyst is arranged in at least one tube through which ammonia flows. In the combustion chamber of the reactor (18), a mixture of ammonia and hydrogen is preferably combusted, wherein the nitrogen formed in the reaction is an inert component that serves as an additional heat carrier.A mixture of hydrogen and ammonia is advantageous because it has a medium flame temperature, better combustion properties than pure ammonia and, depending on the mixing ratio, less NO. X emitted than the two pure substances.

[0030] The state-of-the-art processes for the recovery of H2 from NH3 are not satisfactory in all respects and there is a need for improved processes that can be carried out economically on an industrial scale.

[0031] The state-of-the-art processes have safety-related disadvantages. The process gas in the main process train or the flue gas serves as the heat transfer medium for the preheating and evaporation of NH3. In these state-of-the-art processes, NH3 Suitably connected heat exchangers extract heat directly from the process gas or flue gas. In both cases, the heat exchanger on the liquid or evaporating NH3 side has the higher pressure. If a heat exchanger were to be damaged during this type of process, e.g., if a pipe bursts, which can certainly occur in large-scale industrial plants, then, due to the pressure drop, significant amounts of NH3 would flow either into the main process line or into the flue gas.

[0032] If significant amounts of NH3 were to flow into the main process line, the gaseous NH3 would flow from there into the H2 separation system, e.g., a pressure swing adsorption device. While pressure swing adsorption devices can be configured to remove polar substances such as NH3, a significant increase in the applied amount could lead to a breakdown, which would cause NH3 to flow directly into the product stream.

[0033] If NH3 were to flow into the flue gas in significant quantities, the NH3 would be emitted into the environment through the chimney.

[0034] It is an object of the invention to provide an advantageous plant and process for producing H2 by catalytic decomposition of NH3. The production of H2 should be safe, economical, and feasible on an industrial scale.

[0035] This problem is solved by the subject matter of the patent claims.

[0036] It was surprisingly found that water can be used preferentially as a heat transfer medium to heat and evaporate cooled liquid NH3 (reactant).

[0037] According to the invention, NH3 absorbs heat from heated water or steam in suitably connected heat exchangers and thus enters the gas phase. Should a heat exchanger be damaged during the process according to the invention, NH3 would be mixed with the aqueous phase and possibly dissolved therein (approximately 1200 liters of NH3 dissolve in one liter of water at 0°C, and approximately 500 liters of NH3 at 23°C). This efficiently prevents any breakthrough into the product gas or flue gas, thereby improving the safety of the process.

[0038] NH3 is preferably stored cold, e.g., in a tank, and preferably enters the system according to the invention at -33°C. NH3 must be heated and vaporized to carry out the catalytic decomposition reaction. According to the invention, medium-pressure steam or its condensate is preferably used to preheat the NH3 to its boiling point and subsequently vaporize it. These steams are preferably fed countercurrently to the NH3. This process is advantageous with regard to the safety of the system, as it prevents NFF emissions into the flue gas or process gas in the event of damage to the heat exchanger involved (e.g., due to a pipe burst).

[0039] According to the invention, water serves as the heat transfer medium for heating and evaporating NH3. Depending on the pressure conditions, both water and NH3 can be independent of each other in liquid or gaseous form (water vapor, NH3 vapor). With regard to water as a heat transfer medium, which transfers heat to NH3, it is useful to make the following distinction: (a) steam, preferably medium-pressure steam, preferably with a pressure in the range of 10 to 40 bar and with a temperature in the range of about 180°C to about 250°C; (b) liquid warm water, preferably with a temperature in the range of > 44°C to 90°C; (c) liquid heated cooling water of higher temperature, preferably with a temperature in the range of > 32°C to 44°C; and (d) liquid heated cooling water of lower temperature, preferably having a temperature in the range of 20°C to 32°C.

[0040] It has been found that measures to save water vapor for the preheating and evaporation of NH3 lead to an increase in the yield of H2, provided that the resulting reduction in the amount of energy required (released) is integrated back into the overall process elsewhere. Such a saving in water vapor is preferably achieved according to the invention in that the amount of energy for preheating the NH3 is provided by other water streams, in particular by heated cooling water which is in liquid form, i.e. not in the form of water vapor. The NH3, which has been preheated by absorbing heat from these water streams and is either still liquid or already evaporated under the given pressure conditions, can then be further heated by absorbing heat from water vapor, preferably from medium-pressure water vapor.

[0041] The NH3 entering the plant is cold enough to use the cooling water produced in the plant as a heat source.

[0042] In preferred embodiments, behind an inventive NfU evaporation device in which water vapor releases heat to NH3 and condenses, the resulting condensed water vapor (i) the blowdown is added, which occurs during the generation of water vapor in an H2O evaporation device according to the invention; and / or (ii) excess heated boiler feed water is added, which is preheated by absorbing heat from product gas and / or flue gas, the excess amount resulting from the fact that more boiler feed water is heated than is required to generate water vapor in an H2O evaporation device according to the invention.

[0043] The invention relates to a plant for producing H2 by catalytic decomposition of NH3 comprising - a combustion device for burning a combustion gas to produce combustion heat and flue gas; - an NH3 evaporation device for evaporating liquid NH3 by absorbing heat from heated water, preferably water vapor; - in the flow direction of the NH3 downstream of the NH3 evaporation device, an Nfh reduction device for the catalytic decomposition of evaporated NH3 by absorbing combustion heat generated in the combustion device and producing a product gas comprising H2 and N2; - in the flow direction of the flue gas downstream of the combustion device, a flue gas heat exchanger for heating water, preferably for heating or generating steam, by absorbing heat from the flue gas; and / or in the flow direction of the product gas downstream of the NFh combustion device, a product gas heat exchanger for heating water, preferably for heating or generating steam, by absorbing heat from the product gas; and - a line for the heated water from the flue gas heat exchanger and / or the product gas heat exchanger to the NHs evaporation device.

[0044] The plant according to the invention preferably comprises a device for purifying H2, preferably a pressure swing adsorption device.

[0045] In preferred embodiments of the plant according to the invention, the plant is designed for a throughput based on H2 of at least 500 mol-h 1 designed, preferably at least 1000 mol-h 1 , preferably at least 5000 mol-h 1 , more preferably at least 10,000 mol-h 1 , most preferably at least 50,000 mol-h 1 , and in particular at least 100,000 mol-h 1 .

[0046] In preferred embodiments of the plant according to the invention, the plant comprises a tank for liquid NH3, which has a volume of at least 50 m 3 has, preferably at least 100 m 3, preferably at least 500 m 3 , more preferably at least 1000 m 3 , preferably at least 5000 m 3 , and in particular at least 10,000 m 3 .

[0047] In preferred embodiments of the plant according to the invention, the NH3 decomposition device comprises at least three, preferably at least four, more preferably at least five, even more preferably at least six, most preferably at least seven and in particular at least eight catalyst beds, each comprising NH3 decomposition catalyst; wherein each catalyst bed is preferably present in a tube; wherein the catalyst beds are preferably connected in parallel.

[0048] In preferred embodiments of the plant according to the invention, the Nfh reduction device comprises at least one catalyst bed which comprises Nfh reduction catalyst, wherein the length of the catalyst bed in the flow direction for NH3 is at least 1.0 m, preferably at least 1.5 m, more preferably at least 2.0 m, even more preferably at least 2.5 m, most preferably at least 3.0 m and especially at least 3.5 m; wherein the catalyst bed is preferably present in a tube.

[0049] In preferred embodiments of the plant according to the invention, the combustion device comprises at least three, preferably at least four, more preferably at least five, even more preferably at least six, most preferably at least seven and in particular at least eight burners for combustion of the combustion gas.

[0050] In preferred embodiments of the plant according to the invention, the flue gas heat exchanger and / or the product gas heat exchanger is a tube heat exchanger or tube bundle heat exchanger.

[0051] Preferably, the plant according to the invention comprises a return line and a branching line for the residual gas mixture from the device for purifying H2, preferably a pressure swing adsorption device, to the combustion device.

[0052] The invention also relates to the use of a plant according to the invention for producing H2.

[0053] The invention further relates to a process for producing H2 by catalytic decomposition of NH3 comprising the steps: (a) burning a combustion gas to produce heat of combustion and flue gas; (b) optionally, preheating NH3 by absorbing heat from heated cooling water; preferably wherein the heated cooling water has previously absorbed heat from the product gas before carrying out a purification of H2, preferably a pressure swing adsorption, and / or from H2 after its compression; (c) optionally, preheating NH3 by absorbing heat from water; and heating the water thus obtained by absorbing heat from the flue gas; preferably wherein the water is circulated. (d) optionally, heating NH3 by absorbing heat from water obtained by step (e); (e) evaporation of liquid NH3 by absorption of heat from heated water, preferably water vapor; (f) catalytic decomposition of NH3 vaporized in step (e) by absorbing heat of combustion generated in step (a) and producing a product gas comprising H2 and N2; and (g) heating water, preferably heating or generating steam, by absorbing heat from the flue gas generated in step (a) and / or from the steam generated in step (f). Product gas; and introducing the heated water or the heated or generated steam into step (e).

[0054] Steps (b), (c), and (d) of the process according to the invention are optional, independently of one another. Preferably, steps (a) to (g), if implemented, are carried out in alphabetical order.

[0055] In preferred embodiments of the process according to the invention, in step (f) a throughput based on H2 of at least 500 mol-h 1 achieved, preferably at least 1000 mol-h 1 , preferably at least 5000 mol-h 1 , more preferably at least 10,000 mol-h 1 , most preferably at least 50,000 mol-h 1 , and in particular at least 100,000 mol-h 1 .

[0056] In preferred embodiments of the process according to the invention, in step (e) the liquid NH; is taken from a tank with a volume of at least 50 m 3 taken, preferably at least 100 m 3 , preferably at least 500 m 3 , more preferably at least 1000 m 3 , preferably at least 5000 m 3 , and in particular at least 10,000 m 3 .

[0057] In preferred embodiments of the process according to the invention, in step (f), the catalytic decomposition of NH2 takes place on at least three, preferably at least four, more preferably at least five, even more preferably at least six, most preferably at least seven and in particular at least eight catalyst beds, each comprising NH3 decomposition catalyst; wherein each catalyst bed is preferably present in a tube; wherein the catalyst beds are preferably flowed through in parallel by NH;

[0058] In preferred embodiments of the process according to the invention, in step (f), the catalytic decomposition takes place on at least one catalyst bed comprising NH s decomposition catalyst, wherein the length of the catalyst bed in the flow direction for NH 2 is at least 1.0 m, preferably at least 1.5 m, more preferably at least 2.0 m, even more preferably at least 2.5 m, most preferably at least 3.0 m and in particular at least 3.5 m; wherein the catalyst bed is preferably present in a tube

[0059] In preferred embodiments of the process according to the invention, in step (a) the combustion of the combustion gas is carried out with the aid of at least three, preferably at least four, more preferably at least five, even more preferably at least six, most preferably at least seven and in particular at least eight burners.

[0060] In preferred embodiments of the process according to the invention, the heating in step (g) takes place in a heat exchanger selected from tube heat exchangers and tube bundle heat exchangers.

[0061] According to the invention, the catalytic decomposition of NH2 means the formation of N2 and H2, occasionally referred to in the prior art as "cleavage" or "cracking" of NH2. According to the invention, the catalytic decomposition of NH2 preferably takes place in the absence of O2.

[0062] The invention preferably comprises the following measures: (i) evaporation of NH3; (ii) catalytic decomposition of NH3 with the addition of heat to obtain a product gas comprising N2, H2 and optionally undecomposed NH3 and H2O; (iii) heat recovery; (iv) recovery of non-decomposed NH3, if necessary; (v) Purification of H2. Heat recovery for evaporation of NH3 using water as heat transfer medium

[0063] The recovery of heat according to the invention is an essential aspect of the invention because the catalytic decomposition of NH3 takes place at elevated temperature in the gas phase and the resulting residual heat should be used as efficiently as possible for economic and ecological reasons.

[0064] According to the invention, heat is provided by combustion of a combustion gas in a combustion device. A first portion of the heat generated during combustion preferably flows into an NPh conversion device in which the NPh conversion catalyst is present, for example in the form of one or more catalyst beds. There, the endothermic catalytic decomposition of NH3 takes place. A second portion of the heat generated during combustion preferably leaves the combustion device with the flue gas and enters a flue gas duct.

[0065] According to the invention, the following sources are available for heat recovery: - the hot product gas leaving the NFE decomposition device, and - the hot flue gas leaving the combustion device.

[0066] The hot product gas typically represents a larger mass flow than the hot flue gas, but the temperature of the product gas is typically lower than the temperature of the flue gas. Through efficient heat integration, heat can be extracted from the product gas and the flue gas to a suitable extent, thereby increasing the overall yield.

[0067] According to the invention, heated water, preferably steam, serves as the heat transfer medium for transferring heat from product gas or flue gas to NH3 for the purpose of heating and evaporating it.

[0068] The steam is preferably generated in an FEO evaporation device, which preferably comprises a steam drum and a heat exchanger that are operatively connected to one another. In a preferred embodiment, the FEO evaporation device comprises In another preferred embodiment, the H2O evaporation device comprises, in addition to the steam drum, the product gas heat exchanger, in which water absorbs heat from the product gas. In another preferred embodiment, the H2O evaporation device comprises, in addition to the steam drum, the flue gas heat exchanger, in which water absorbs heat from the flue gas. In a further preferred embodiment, the H2O evaporation device comprises, in addition to the steam drum, both the product gas heat exchanger, in which water extracts heat from the product gas, and the flue gas heat exchanger, in which water absorbs heat from the flue gas.

[0069] To generate steam, boiler feedwater is fed into the steam drum. If more boiler feedwater is fed in than steam is removed, a surplus of heated boiler feedwater results, which can be separated from the steam and used like other heated cooling water, particularly for heating NH3.

[0070] The heat contained in the hot product gas and / or flue gas is preferentially absorbed by the water, heating or generating steam. The steam is fed via a pipe system into the NH3 evaporation unit, where the NH3 absorbs heat from the steam, is heated, and finally evaporates itself.

[0071] In a preferred embodiment, boiler feed water is preheated in the flue gas duct, then a bypass stream is branched off from it and the remaining preheated boiler feed water is fed into the steam drum.

[0072] In another preferred embodiment, no bypass stream is diverted, but the entire amount of preheated boiler feedwater is fed into the steam drum. Any excess water is then preferably discharged from the steam drum in a liquid state. This allows more heat to be extracted from the process gas (flue gas or product gas), which can be advantageous if excess heat is available there.

[0073] After leaving the NH3 evaporation device, the heated and evaporated NH3 is then heated to an even higher temperature level, as is desirable or necessary for the catalytic decomposition of NH3, and finally fed to the NH3 decomposition device.

[0074] For economical process operation, only medium temperature levels for the heated NH3 (<300°C) can be achieved with steam. Therefore, starting from a medium temperature level achieved with the aid of steam, for the further heating of NH3 to a high temperature level (>300°C), according to the invention, at least one heat exchanger, preferably at least two heat exchangers, is subsequently used, in which the NH3 absorbs heat from the hot product gas and / or the hot flue gas.

[0075] Additional heat, which is required to reach the desired decomposition temperature or to maintain the endothermic catalytic decomposition, is Preferably, the heat is supplied directly by a heat flow from the combustion device to the NH3 decomposition device. For this purpose, the NH3 decomposition device and the combustion device preferably jointly form a reactor, which is designed analogously to a primary reformer.

[0076] The heat recovery according to the invention can preferably fulfill the following tasks, for example: - Preheating of water (e.g. boiler feed water); - Preheating of NH3; - Generation of steam; - Evaporation of NH3; and - Preheating of combustion air.

[0077] According to the invention, various combination options are available for the arrangement of the system components for heat recovery.

[0078] Preferably, heat contained in the flue gas stream of the combustion device and / or heat contained in the product gas stream of the NFh combustion device is used in at least three, preferably in at least four, particularly preferably in at least five heat exchangers arranged one behind the other in the flow direction of the flue gas stream or product gas stream, preferably for different sub-processes of the method.

[0079] The evaporation of NH3 using the NFF evaporation device according to the invention and a preferred preheater is explained in more detail below.

[0080] In the NFE evaporator, NH3 absorbs heat from water, preferably water vapor, and enters the gas phase. The temperature of the NH3 upon entering the NH3 evaporator is preferably in the range of approximately 60±30°C, more preferably approximately 60±15°C. The temperature of the NH3 upon exiting the NFk evaporator is preferably in the range of approximately 60±30°C, more preferably approximately 60±15°C.

[0081] Preferably, at least one heat exchanger is arranged downstream of the NFE evaporation device in the flow direction of the NH3, which is either the product gas heat exchanger or the flue gas heat exchanger. Preferably, at least two heat exchangers are arranged downstream of the NFE evaporation device in the flow direction of the NH3, which are the product gas heat exchanger and the flue gas heat exchanger. The heated water, preferably steam, supplied as a heat source for the operation of the NFE evaporation device is generated in the product gas heat exchanger by absorbing heat from the product gas and / or in the flue gas heat exchanger by absorbing heat from the flue gas. The heat in the product gas and / or flue gas is used to heat or generate steam in a H20 evaporation device and this water vapor is fed to the NH3 evaporation device.

[0082] Preferably, the water vapor, possibly in the form of water vapor condensate, is reused after leaving the NH3 evaporation device, namely as a heat medium in NH3 preheating and NH3 evaporation.

[0083] This preferably occurs in at least a two-stage process in which NH3 and steam, or its steam condensate, are conducted in countercurrent. Due to the relationship between the condensation enthalpy of the steam and the free enthalpy of its steam condensate, the condensation of the steam alone may not be sufficient to evaporate the NH3 if the steam condensate is to be released at an acceptable temperature of, for example, 40°C. Therefore, according to the invention, a preheater is preferably used, in which the evaporation of the NH3 may already have begun in part.

[0084] The preheater is preferably arranged upstream of the NFF evaporator in the direction of NH3 flow to preheat NH3. In the preheater, NH3 absorbs heat from water, preferably steam condensate. The temperature of the NH3 entering the preheater is preferably in the range of approximately -35±10°C, more preferably approximately -35±5°C. The temperature of the NH3 leaving the preheater is preferably in the range of approximately 60±30°C, more preferably approximately 60±15°C.

[0085] The steam flow is preferably adjusted so that essentially only steam condensate leaves the NFE evaporator. In preferred embodiments, blowdown and / or boiler feedwater, e.g., from a bypass, can be mixed with this steam condensate (see below).

[0086] Preferably, generated steam and generated steam condensate are passed in countercurrent through the preheater and the NFk evaporation device.

[0087] The NH3 passes through the preheater, where it absorbs heat from steam condensate in countercurrent. The energy input is high enough to heat the NH3 to its boiling point and partially evaporate it. Preferably, at least 5%, more preferably at least 10%, even more preferably at least 15%, most preferably at least 20%, and especially at least 25% of the total NH3 flow is evaporated in the preheater. For example, the vapor content of the NH3 can be up to 35%.

[0088] The preheater preferably contains a device for separating the two NFF phases, so that the unevaporated remainder of the NH3 enters the NH3 evaporation device at boiling temperature, and the gaseous NH3 is transported in a separate pipeline.

[0089] Alternatively, both phases of the NH3 can also enter the NH3 evaporation device in a common pipeline.

[0090] In the NH3 evaporation system, steam serves as the heat medium, for example, saturated steam at 33.5 bar a and a temperature of 239.8°C. The steam ensures the complete evaporation of the NH3, preferably via a device integrated into the heat exchanger for separating the two phases. Both gaseous NH3 streams are preferably combined and fed further into the process.

[0091] For the NHs evaporation system described above and the preheater, if present, water or steam is used, which has previously absorbed heat from the flue gas and / or product gas.

[0092] According to the invention, heat from heated cooling water is preferably used in addition to heating NH;.

[0093] Heated cooling water, which is preferably used according to the invention for heating NH;, is preferably obtained at - cooling the product gas with the aid of a process cooler in the flow direction of the product gas upstream of a device for purifying H2, preferably a pressure swing adsorption device; - cooling the steam condensate by means of a steam condensate heat exchanger in the flow direction of the steam condensate downstream of the NHs evaporation device and preferably downstream of any preheater; - cooling the H2 product by means of a heat exchanger in the flow direction of the ^ product downstream of an H2 compressor, possibly upstream of a second H2 compressor; and / or - cooling the flue gas with the help of a flue gas heat exchanger in the flue gas duct.

[0094] In preferred embodiments of the invention, the yield of H2 is increased by relatively reducing the amount of steam generated, and the resulting reduced heat remains in the process, thus requiring less combustion gas. The energy gap resulting from the relatively lower amount of steam provided for preheating and evaporating NH3 is preferably closed by preheating NH3 with the heated cooling water.

[0095] For this purpose, a preheating device is preferably arranged in the flow direction of the NH3 downstream of the tank and upstream of the NHs evaporation device, preferably also in the flow direction of the NH3 upstream of any preheater that may be present, which preheating device preferably serves to preheat the NH3 and in which NH3 absorbs heat from water, which in turn has previously accrued elsewhere as heated cooling water.

[0096] Preferably, the heated cooling water is taken from a process cooler upstream of a device for purifying H2, preferably a pressure swing adsorption device, in the flow direction of the product gas, where it has previously absorbed heat from the product gas. Preferably, the heated cooling water is additionally or alternatively taken from a heat exchanger of a possible TB compressor, where it has previously absorbed heat from compressed H2. Preferably, the heated cooling water is additionally or alternatively taken from a steam condensate heat exchanger located downstream of the NH3 evaporation device.

[0097] Preferably, additional heat from the condensed steam is utilized, i.e., the steam condensate is cooled before being returned for treatment. For this purpose, a steam condensate heat exchanger is preferably arranged downstream of the NH3 evaporator in the flow direction of the steam condensate.

[0098] If a preheater is installed upstream of the NH3 evaporator, the steam condensate heat exchanger is preferably located downstream of the preheater in the direction of steam condensate flow. The steam condensate then preferably leaves the NH3 evaporator first and is returned to the preheater, where NH3 absorbs heat from the steam condensate and is thus preheated. The steam condensate then enters the steam condensate heat exchanger, where cooling water absorbs heat from the steam condensate. The thus heated cooling water can be used elsewhere, for example, to preheat liquid NH3.

[0099] In addition, the flue gas can also be cooled with cooling water. This can be useful, for example, if there is no IT compressor and therefore not enough heated cooling water is available to provide the required amount of heat for preheating and evaporating the NH3.

[0100] The sources for heated cooling water preferred according to the invention are illustrated in Figure 11, wherein it is possible according to the invention that only one of these sources, several of these sources, or all of these sources are used for preheating and, if necessary, evaporating NH3.

[0101] The pre-temperature at which fresh, i.e., not yet heated, cooling water is typically supplied depends on the site's climate. The cooling water removes process heat by heating it by a temperature difference of typically about 8°C to about 15°C. The heat absorbed by the cooling water is then preferentially used to preheat liquid NH3 (see Figure 7).

[0102] The temperature of the cooling water or heated cooling water is therefore preferably significantly below the temperature of the water or water vapor used in the NH3 evaporation device according to the invention for evaporating NH3. The temperature is preferably The temperature of the heated cooling water should not exceed 100°C, preferably not exceed 80°C, and even more preferably not exceed 60°C. For example, on the Arabian Peninsula, a cooling water return temperature of approximately 50°C can be expected, while in Central Europe, approximately 30°C is more likely.

[0103] As already mentioned, according to the invention a distinction is made between liquid heated cooling water of higher temperature (preferably > 32°C to 44°C) on the one hand, and liquid heated cooling water of lower temperature (preferably 20°C to 32°C) on the other hand.

[0104] If liquid heated cooling water of a lower temperature is used to heat NH3, it is preferred according to the invention to use a heat exchanger in the flue gas duct to generate this liquid heated cooling water of a lower temperature (Figures 10, 14, and 16, additional heat exchanger 71), thus preheating the NH3 to its boiling point. The subsequent evaporation of the thus heated NH3 is then preferably achieved solely by heat from the steam condensate.

[0105] If liquid, heated cooling water at a higher temperature is used to heat NH3, the NH3 can be preheated to significantly higher temperatures. In this case, a heat exchanger can be provided in the flue gas duct to absorb heat from the flue gas. This is particularly useful if there is no H2 compressor, meaning that there is no heat exchanger downstream of the H2 compressor, which would otherwise produce heated cooling water at a higher temperature. Alternatively, such an H2 compressor is available. In this case, a heat exchanger downstream of the H2 compressor or between several H2 compressors preferably provides a sufficient amount of heated cooling water at a higher temperature.

[0106] For example, if a total output of 709 kW is required to preheat and evaporate NH3, 409 kW can be generated by condensing steam and the remaining 300 kW by heat transfer from steam condensate without the use of heated cooling water. With a sufficiently large quantity of cooling water (e.g. heated from 25°C to 35°C), NH3 can be preheated with an output of 115 kW, which brings the NH3 to a temperature of 12°C. Subsequently, only 252 kW of power is required for preheating and 342 kW for evaporation. By appropriately integrating the heat released in this way into the process gas, a plant yield increase of, for example, 0.4 to 0.5% can be achieved.

[0107] Furthermore, according to the invention, in addition to heating NH3, heat from water is preferably used, which absorbs heat from the flue gas, then releases this heat to NH3 for preheating, then absorbs heat from the flue gas again, etc. The water is therefore preferably circulated in a circle for this purpose.

[0108] Warm water (>44-90°C) or heated cooling water are preferably not used to evaporate the NH3, but only to preheat it to its boiling point. With preheating, a minimally higher temperature of the heat transfer medium of only 10 K relative can still lead to an economical design of a heat exchanger. In contrast, with evaporation, the heat transfer medium should be at least 40 K hotter relative at its coldest point. For this to happen, the warm water or the heated cooling water would have to have a significantly higher temperature, i.e., heat would have to be extracted from the flue gas and / or product gas at a higher temperature to generate it. According to the invention, however, it is precisely the low temperature levels that are preferably used to generate heated cooling water, in particular the low temperature levels of the flue gas, and therefore preferably only a preheating of NH3 occurs, but not additional evaporation.

[0109] In preferred embodiments of the invention, an additional heat exchanger is provided in the flow direction of the NH3; downstream of the tank and upstream of the NH3 evaporation device, preferably in the flow direction of the NH3; downstream of any preheating device, preferably in the flow direction of the NH3; upstream of any preheater, which is present, which heat exchanger preferably serves to preheat the NH3 and in which NH3; absorbs heat from water, which is preferably circulated in the circuit and which has previously absorbed heat from the flue gas.

[0110] For this purpose, the additional heat exchanger is preferably operatively connected to another heat exchanger. The additional heat exchanger is preferably arranged downstream of the flue gas heat exchanger in the direction of flue gas flow and serves to heat the water by absorbing heat from the flue gas. The additional heat exchanger and the additional heat exchanger are preferably connected to each other via a ring line through which the water is circulated, preferably by means of a pump.

[0111] The temperature of this water or heated water is thus preferably significantly below the temperature of the water or water vapor used in the NH3 evaporation device according to the invention for evaporating NH3. The temperature of the heated water (i.e., after absorption of heat from the flue gas) is preferably at most 110°C, more preferably at most 100°C, even more preferably at most 90°C.

[0112] Even after passing through several heat exchangers, in which it has given off heat to water or NH; as the heat transfer medium and has thus been cooled, the flue gas typically still has a comparatively high temperature of, for example, about 150°C. If the flue gas falls below a temperature of about 120°C, the preheating of the combustion air in a heat exchanger arranged in the flue gas duct by absorbing heat from the flue gas is no longer satisfactory, as it requires a relatively high temperature difference (see Figures 8 and 9, heat exchanger 43). The residual heat contained in the flue gas cannot therefore be integrated into process streams.

[0113] The flue gas also contains a high N2 content: A portion of N2 is released during the combustion of NH3. A portion of N2 is present in the combustion air. A portion of N2 is generated during the catalytic decomposition of NH3 and, if necessary, returned to the combustion device from a device for purifying H2, preferably a pressure swing absorption device. Due to the high N2 content, the dew point of the flue gas is very low under the prevailing pressure conditions, e.g., at approximately 60°C. To avoid condensation, which could lead to damage to the heat exchangers installed in the flue gas duct, a temperature difference of 25°C is preferably maintained as a safety margin from the dew point, according to the invention.

[0114] This residual heat in the flue gas (temperature range from approximately 85°C to approximately 120°C) is preferably utilized by absorbing it into the water circulating in the circuit. For this purpose, an additional heat exchanger is preferably provided in the flue gas duct, through which water circulates as a heat transfer medium, preferably driven by a pump (see Figure 10).

[0115] The water is heated in this additional heat exchanger, for example, from about 40°C to about 90°C and can then serve as a heat source for NH3, which has advantageously already been preheated by the cooling water.

[0116] For example, at a flue gas outlet temperature of 90°C (see Figure 16), which complies with the distance criterion from the dew point, a power of 101 kW can be absorbed and used to heat NH3 until the boiling point of the NH3 is reached. The preheater arranged downstream in the direction of flow of the NH3 increases the proportion of vaporized NH3 to approximately 34%. The NEL evaporation device used in the fourth stage then only requires a power of, for example, 320 kW. Compared to a two-stage heating and evaporation of NH3, the amount of heat required to generate steam can be almost halved in this way. This allows the yield in relation to the amount of H2 produced to be increased by, for example, approximately 0.3%.

[0117] The use of water or steam for preheating, heating, and evaporating the initially liquid NH3 is economically and safety-wise advantageous compared to the otherwise equally feasible direct use of flue gas or process gas as a heat source for evaporating NH3. Damage to a pipe could cause NH3 to flow into the exhaust gas and thus into the atmosphere, or enter the process stream. Electrical evaporation of water to generate steam would result in high energy consumption and corresponding costs.

[0118] From a safety and economic point of view, water is therefore advantageous as a heat transfer medium.

[0119] According to the invention, the steam preferably has a slightly higher pressure than the NH3, so that in the event of damage to a heat exchanger (e.g., due to a pipe burst), steam might flow into the NH3. However, due to the comparatively small pressure difference, the water inflow would be minimal.

[0120] In the NH3 evaporation system, the low density of the water vapor would result in a comparatively low mass inflow, but the comparatively high temperature of the water vapor would also result in a significant inflow of energy. This would result in increased evaporation of NH3. However, since the NFE evaporation system and its integrated heat exchanger are intended and designed to evaporate NH3, such increased evaporation of NH3 would be less critical.

[0121] In the preheater, if present, the mass flow from the water would be higher due to the higher density, but the energy flow would be lower.

[0122] NFE evaporation devices preferred according to the invention and preheaters preferred according to the invention are equipped independently of one another in such a way that they remove any water (high boilers) contained in the NH3 as a "blowdown", so that in such a case no water breakthrough would possibly occur in the process.

[0123] If water vapor were to enter the process, the water would be inert in the decomposition of NH3 and, like NH3 in higher concentrations, would pass through the H2 purification device (preferably a pressure swing adsorption device). The presence of water in the FE product is less hazardous to end users.

[0124] In contrast to the inventive use of water as a heat transfer medium, the conventional use of process heat directly from the product gas or flue gas to evaporate NH3 would instead result in the NH3 being at a higher pressure. Compared to the product gas or flue gas, there would be a significant pressure difference, so that in the event of damage to a heat exchanger (e.g., due to a pipe burst), a high mass inflow would occur due to the high pressure difference and the high density of the liquid NH3. A breakthrough of NH3 into the flue gas would lead to emissions from the stack and cause significant environmental pollution. A breakthrough of NH3 into the product gas would cause the NH3 to pass into the flue gas product, which could be quite dangerous for end users.

[0125] Preferably, at least two heat exchangers are used for the evaporation of NH3, in which NH3 is first preheated to the boiling point and then evaporated.

[0126] To improve safety, the preheating, heating and evaporation of the NH3 are decoupled from the decomposition of the NH3 and the further process path. Currents

[0127] Preferred embodiments of the invention are explained below with reference to the various streams that are preferably used or formed when carrying out the process according to the invention or when operating / using the system according to the invention. For this purpose, the following streams are conveniently distinguished below: • NH3: o from storage until before catalytic decomposition; o catalytic decomposition; • Combustion gas; • Combustion air; • Product gas: o after catalytic decomposition until before purification of EL; o separation of residual amounts of undecomposed NH3; o purification of H2 and separation of residual gas mixture; • H2 - after purification until storage; • Residual gas mixture; • Flue gas; and • Water or water vapor.

[0128] The following explanations apply equally to the system according to the invention, the use of the system according to the invention, and the method according to the invention. Reference is made in part to the figures in order to illustrate a possible and possibly preferred integration of individual components or steps into the system according to the invention or the method according to the invention. However, this does not mean that all other components shown in the respective figures or associated steps must necessarily be implemented simultaneously. The references to the figures are not to be interpreted in a restrictive manner, but serve merely to illustrate isolated preferred embodiments of the invention. NH3- from storage to catalytic decomposition

[0129] According to the invention, the NH3 is preferably stored as starting material.

[0130] The NH3 stored in a cooled tank is preferably in liquid form, at atmospheric pressure and a temperature below its boiling point of -33.5 °C. NH3 is fed into the plant using a pump, preferably at plant pressure. The increased plant pressure increases the boiling point of the NH3. To convert NH3 into the gas phase, heat must be added to evaporate the NH3. The evaporation of NH3 requires considerable amounts of heat. At a pressure of, for example, 30 bar, approximately 2.4 t / h of NH3 can be preheated and evaporated per megawatt of energy input.

[0131] Before the NH3 can be catalytically decomposed, it is preferably heated successively to several temperature levels according to the invention.

[0132] Starting from liquid NH3, heating and subsequent evaporation of NH3 to a medium temperature level (<300°C) occurs preferentially by absorbing heat from water or water vapor.

[0133] Subsequently, NH3 is preferably further heated to a high temperature level (>300°C) by absorbing heat directly from flue gas and / or product gas, i.e., without water as a heat transfer medium. During these subsequent measures for further heating to a high temperature level (>300°C), the pressure differences and the density of the NH3 in the heat exchangers are significantly lower than during the previous measures for heating and evaporating NH3 to a medium temperature level (<300°C). Therefore, any damage to the heat exchangers (e.g., pipe bursts) would pose far less drastic safety problems during the subsequent measures (temperature level >300°C) than during the previous measures (temperature level <300°C).

[0134] Energy integration preferably brings NH3 to the desired temperature at the inlet to the NRE decomposition unit. In addition, the combustion air is preferably preheated. It is advantageous to preheat and evaporate water or boiler feed water. Since the process heat is present in two streams, the product gas on the one hand and the flue gas on the other, the heat exchangers can be arranged in various variants according to the invention.

[0135] According to the invention, liquid NH3 is preferably evaporated by absorbing heat from hot steam. This hot steam is in turn generated from water or cooler steam.

[0136] For the purposes of this description, unless explicitly stated otherwise, the term "water" is used for all its states of matter. Depending on temperature and pressure, this water can exist in liquid or gaseous form, or as a two-phase system, i.e., possibly also as water vapor. This also applies analogously to "NH3."

[0137] Preferably, the water absorbs heat from the flue gas downstream of the combustion device in the direction of flue gas flow and / or heat from the product gas downstream of the NRE decomposition device in the direction of product gas flow. For this purpose, suitable heat exchangers are preferably provided and connected in the system according to the invention.

[0138] Depending on the reaction temperature, the amount of heat contained in the product gas may be lower than the amount of heat contained in the combustion gas. This may influence the heat recovery. For example, at comparatively low temperatures at the outlet of the NFE decomposition device (e.g., approximately 500°C), the amount of heat in the product gas is significantly lower than in the flue gas. In such a case, according to the invention, steam generation is preferably carried out largely or entirely with Heat is extracted from the flue gas from the combustion system. Although this variant of connecting the heat recovery components has the disadvantage of a lower temperature gradient between the flue gas and the incoming water, this can be compensated for by a larger NH3 evaporation system or a reduction in the pressure level.

[0139] According to the invention, it may also be preferable to provide two NH3 evaporation devices, which may be connected in parallel. The NH3 is then preferably first heated in a preheater and then fed via two parallel lines into a first NH3 evaporation device and a second NE3 evaporation device. Preferably, the second NH3 evaporation device can be fed with steam, while steam condensate is supplied to the first NE3 evaporation device. After flowing through the first evaporation device, the steam condensate preferably reaches the preheater and flows through it, also releasing heat.

[0140] In preferred embodiments of the invention, water in the flow direction of the flue gas downstream of the combustion device absorbs heat from the flue gas in at least one first heat exchanger and at least one second heat exchanger, wherein the flue gas has a higher temperature when flowing through the first heat exchanger than when flowing through the second heat exchanger (cf. Figure 10, first heat exchanger: flue gas heat exchanger 52; second heat exchanger: further heat exchanger 71).

[0141] According to the invention, preferred stations through which the NH3 preferably passes on its way from the tank to the NEE decomposition device are explained below.

[0142] In preferred embodiments of the invention, liquid NH3 leaves a tank and is pumped into the plant at system pressure. To evaporate the NH3, the NH3 evaporation device is arranged downstream of the tank in the direction of NH3 flow. In this device, NH3 absorbs heat from water vapor, which in turn has previously absorbed heat from product gas and / or flue gas (see Figures 1-10, NEfi evaporation device 14).

[0143] Preferably, a preheater is arranged downstream of the tank and upstream of the NEL evaporation device in the direction of flow of the NH3. This preheater preferably serves to heat the NH3 to the desired temperature at the inlet to the NEE evaporation device and in which NH3 absorbs heat from water, which in turn has previously left the NEE evaporation device as steam condensate. Steam and steam condensate are preferably passed in countercurrent through the preheater and the NEE evaporation device (see Figures 4-10, preheater 13).

[0144] Preferably, a first heat exchanger is arranged in the flow direction of the NH3 downstream of the NEE evaporation device, which preferably serves to further heat the NH3 and in which NH3 preferentially absorbs heat from product gas (see Figures 8 and 9, heat exchanger 20).

[0145] Preferably, a second heat exchanger is arranged downstream of the first heat exchanger in the flow direction of the NH3, which second heat exchanger preferably serves to further heat the NH3 and in which NH3 preferably absorbs heat from flue gas (see Figures 8 and 9, heat exchanger 22).

[0146] In preferred embodiments of the invention, when the catalytic decomposition of the NH3 takes place in two stages in a first NH3 decomposition device (pre-reactor) and a second NEFI decomposition device, a further heat exchanger is preferably arranged in the flow direction of the NH3 downstream of the first NEFI decomposition device (pre-reactor) and preferably upstream of the second NEFI decomposition device, which heat exchanger preferably serves to heat the intermediate product gas after leaving the first NEFI decomposition device (pre-reactor) and before entering the second NEFI decomposition device (together with the combustion device analogous to the primary reformer) and in which NH3 preferentially absorbs heat from flue gas (cf. Figure 9, further heat exchanger 67).

[0147] In preferred embodiments of the invention, a preheating device is arranged in the flow direction of the NH3 downstream of the tank and upstream of the NEfi evaporation device, preferably also in the flow direction of the NH3 upstream of any preheater present, which preheating device preferably serves to preheat the NH3 and in which NH3 absorbs heat from water, which in turn has previously accrued as cooling water at another location, preferably in a process cooler in the flow direction of the product gas upstream of a device for purifying H2, preferably a pressure swing adsorption device, or in a heat exchanger of an EE compressor (cf. Figures 7 and 10, preheating device 70).

[0148] In preferred embodiments of the invention, an additional heat exchanger is provided in the flow direction of the NH3 downstream of the tank and upstream of the NEfi evaporation device, preferably in the flow direction of the NH3 downstream of any preheating device, preferably in the flow direction of the NH3 upstream of any preheater, which is present, which heat exchanger preferably serves to preheat the NH3 and in which NH3 absorbs heat from water, which is preferably circulated in the circuit and which has previously absorbed heat from the flue gas (see Figure 10, additional heat exchanger 73).

[0149] According to the invention, liquid NH3 is preferably heated in at least one stage, more preferably in at least two stages, even more preferably in at least three stages, particularly preferably in at least four stages, and converted from the liquid phase to the gas phase, i.e., evaporated. In this process, the NH3 preferably reaches a medium temperature level (<300°C).

[0150] In single-stage heating and evaporation, the liquid NH3 is preferably heated in a single stage and also evaporated immediately (see Figures 1 to 3). In preferred embodiments of the invention, at least one heat exchanger is provided and connected for this purpose (see Figure 1, flue gas heat exchanger 52; Figure 2, product gas heat exchanger 26). In other preferred embodiments of the invention, at least two heat exchangers are provided and connected for this purpose (see Figure 3, product gas heat exchanger 26 and flue gas heat exchanger 52).

[0151] In two-stage heating and evaporation, the NH3 is preferably first heated in a first stage (but not yet completely evaporated) and then evaporated in a second stage (see Figures 4 to 6, 8, 9). In preferred embodiments of the invention, at least one heat exchanger is provided and connected for the first stage and at least one heat exchanger for the second stage (see Figure 4, Stage 1: preheater 13; Stage 2: product gas heat exchanger 26 or flue gas heat exchanger 52). In other preferred embodiments of the invention, at least one heat exchanger is provided for the first stage and at least two heat exchangers are provided for the second stage (see Figures 5, 6, 8 and 9, Stage 1: preheater 13; Stage 2: product gas heat exchanger 26 and flue gas heat exchanger 52).

[0152] In three-stage heating and evaporation, the liquid NH3 is preferably first preheated in a first stage (but not yet completely evaporated), then further heated in a second stage (but also not yet completely evaporated) and finally evaporated in a third stage (see Figure 7).

[0153] In preferred embodiments, the ratio of condensation enthalpy to latent heat of the steam condensate is such that the preheater already evaporates a certain portion of the NH3 even in two-stage operation. If, instead, the preheater were to be used exclusively for preheating, achieving the evaporation of NH3 solely via the condensation enthalpy of the steam, the amount of steam would have to be significantly increased, and the steam condensate would exit with a very high residual temperature, which would be disadvantageous.

[0154] In preferred embodiments of the invention, at least one heat exchanger is provided and connected for the first stage, at least one heat exchanger for the second stage, and at least one heat exchanger for the third stage (see Figure 7, Stage 1: preheating device 70; Stage 2: preheater 13; Stage 3: product gas heat exchanger 26 or flue gas heat exchanger 52). In other preferred embodiments of the invention, at least one heat exchanger is provided for the first stage, at least one heat exchanger for the second stage, and at least two heat exchangers for the third stage (not shown in the figure; corresponds to a variation of Figure 5 or 6 by the embodiment according to Figure 7; Stage 1: Preheating device 70; Stage 2: Preheater 13; Stage 3: Product gas heat exchanger 26 and flue gas heat exchanger 52). From Figure 10, a three-stage heating and evaporation of the liquid NH; can also be derived, namely if either preheating device 70 is missing or if the additional heat exchanger 73 is missing.

[0155] In four-stage heating and evaporation, the liquid NH; is preferably first preheated in a first stage (but not yet evaporated), then further heated in a second stage (but also not yet completely evaporated), then further heated in a third stage (but also not yet completely evaporated), and finally evaporated in a fourth stage (see Figure 10). In preferred embodiments of the invention, at least one heat exchanger is provided and interconnected for the first stage, at least one heat exchanger for the second stage, at least one heat exchanger for the third stage, and at least one, preferably at least two, heat exchangers for the fourth stage (see Figure 10, Stage 1: preheating device 70; Stage 2: additional heat exchanger 73; Stage 3: preheater 13; Stage 4: product gas heat exchanger 26 (not shown) and flue gas heat exchanger 52).

[0156] After the NH; has been heated and evaporated, it has preferably reached a medium temperature level (<300°C).

[0157] According to the invention, NH3 is then preferably further heated to a high temperature level (>300°C) by absorbing heat from the flue gas and / or product gas. For this purpose, heat is absorbed in at least one heat exchanger from the product gas in the flow direction of the product gas downstream of the NH3 decomposition device and / or from the flue gas in the flow direction of the flue gas downstream of the combustion device.

[0158] In preferred embodiments of the invention, the further heating of NEW is initially achieved by absorbing heat from the product gas in a dedicated and interconnected first heat exchanger. The first heat exchanger is preferably arranged downstream of the NH3 decomposition device in the flow direction of the product gas and is traversed by the hot product gas on the one hand and the NEW to be further heated on the other. Heat recovered from the product gas is thus used to further heat NEW (see Figures 8 and 9, heat exchanger 20).

[0159] In preferred embodiments of the invention, the further heating of NEW occurs alternatively or subsequently by absorbing heat from the flue gas in a second heat exchanger provided and connected for this purpose. The second heat exchanger is preferably arranged downstream of the combustion device in the flow direction of the flue gas and is traversed by the hot flue gas on the one hand and the NRE to be further heated on the other. Heat recovered from the flue gas is thus used to further heat NEW (see Figures 8 and 9, heat exchanger 22). NH - catalytic decomposition

[0160] The catalytic decomposition of NH3 according to the invention is the actual reaction for the formation of H2, which essentially proceeds thermally but is accelerated by the use of an NH3 decomposition catalyst. According to the invention, the catalytic decomposition of NH3 can be carried out under various conditions using different NEE decomposition catalysts and with various configurations with different reactor types.

[0161] According to the invention, the catalytic decomposition of NH3 is preferably carried out by adding heat in the presence of a NEE decomposition catalyst. Important parameters for the catalytic decomposition of NH3 are the type of NH3 decomposition catalyst, the reaction temperature, and the reaction pressure.

[0162] Various materials can be considered as the NH3 decomposition catalyst according to the invention. The reaction temperature at which the catalytic decomposition of NH3 occurs is determined in particular by the choice of the NH3 decomposition catalyst.

[0163] In preferred embodiments of the invention, a nickel-based NH3 decomposition catalyst is used. The reaction temperature and reaction pressure determine the equilibrium conversion. At 900°C and 20 bar pressure, the decomposition of NH3 is almost quantitative. At 650°C, the NH3 conversion is approximately 98.5%, and at 500°C, only approximately 95%. According to the invention, reaction temperatures are preferably set in the range of approximately 600°C to approximately 900°C, preferably approximately 600°C to approximately 700°C, so that a high conversion is achieved. With regard to energy balance and conversion, optimal reaction temperatures are in the range of approximately 630°C to 640°C. Nickel-based NH3 decomposition catalysts are advantageous despite the comparatively high reaction temperature.Due to the high conversion, the remaining content of undecomposed NH3 in the product gas is comparatively low, so separate separation of undecomposed NH3 for its recovery is preferable. Instead, N2 and undecomposed NH3 are separated together from the product gas by pressure swing adsorption during the purification of H2.

[0164] Preferably, the NH3 decomposition catalyst comprises supported nickel. Preferred support materials are selected from the group consisting of Al2O3, MgO, SiCE, mesoporous SiCE (e.g. MCF-17, MCM-41, SBA-15), zeolite (e.g. HY, H-ZSM-5), BaMnO3, BaTiO3, BaZrO3, CaMnO3, CaTiO3, CaZrO3, CeO2, Gd2O3, GdAlO3, KNbO3, La2O3, LaAlO3, MnO2, NaNbO3, Nb2O5, Sm2O3, SmAlCh, SrMnO3, SrTiO3, SrZrO3, TiO2, Y2O3, ZrO2, carbon (e.g. CNTs, SWCNTs, AX-2I, MSC-30, MESO-C, GNP, activated carbon, graphene, graphene oxide), Attapulgite, hydrocalumite, sepiolite, and mixtures thereof.

[0165] In other preferred embodiments of the invention, a ruthenium-based NH3 decomposition catalyst is used. For this purpose, reaction temperatures in the range of about 450°C to about 500°C, although somewhat lower conversions of, for example, about 95% can be achieved, so that the remaining residual content of non-decomposed NH3 in the product gas is greater.

[0166] Alternatively, other NH3 decomposition catalysts can be used at even lower reaction temperatures. The lower the reaction temperature, the lower the conversion, and the more undecomposed NH3 must be separated from the product gas and recycled.

[0167] According to the invention, the reaction pressure is preferably between about 15 bar a and about 25 bar a. The stoichiometry of the reaction (2 NH3 N2 + 3 H2) increases the volume, which is why an increased reaction pressure generally has a negative effect on the conversion. On the other hand, it is advisable to operate the entire process at higher pressures in order to limit the vessel volume and thus the investment costs. With a reaction pressure of only 1 bar, conversions of more than 99% could be achieved at reaction temperatures above 400°C. However, since a reaction pressure of 1 bar is only practical for very small plants, the plant according to the invention is preferably operated at a higher reaction pressure, even if this entails a certain loss in conversion.

[0168] The reaction pressure is determined in particular by the design of the H2 purification. The pressure swing adsorption (PSA) for purifying H2, which is preferred according to the invention, can preferably be operated effectively at a pressure in the range of about 15 bar to about 25 bar. The pressure of the product gas upon leaving the NEE decomposition device is preferably in the range of about 15 to about 25 bar a, more preferably about 18 bar a to about 22 bar a, even more preferably about 19 bar a to about 21 bar a. In this way, a good balance is found between the requirements of pressure swing adsorption on the one hand and the achieved conversion on the other.

[0169] The decomposition of NH3 can basically take place in different reactor types.

[0170] In adiabatic reaction conditions, the internal heat of the reaction gas is used as the energy source for the reaction. Suitable reactors for this purpose are autothermal reformers and secondary reformers, which operate with internal energy generation. Combustion air is added to the process gas, and a portion of the reaction gas is combusted to raise the temperature to the desired temperature at the reactor outlet. A disadvantage is the presence of water produced during combustion in the process gas, which must be removed by condensation. Some of the undecomposed NH3 then dissolves in the condensed water and is lost. Furthermore, the high temperatures lead to the formation of significant amounts of nitrogen oxides.

[0171] According to the invention, these disadvantages are avoided by physically separating the product gas from the combustion gas and the flue gas formed therefrom. The product gas is formed in the NEE decomposition device according to the invention by decomposition of NH3 and leaves the NH3 decomposition device via its own outlet. The combustion gas is combusted together with combustion air in the combustion device, and the resulting flue gas also leaves the combustion device via its own outlet, preferably into a flue gas duct. The product gas and flue gas are not mixed but remain physically separated. The heat generated during the combustion of the combustion gas flows into the NH3 decomposition device as a heat flow, thus providing the heat required to maintain the endothermic decomposition of NH3.

[0172] The catalytic decomposition of NH3 is preferably carried out isothermally, quasi-isothermally, or in a mixed isothermal and adiabatic process. In isothermal reaction conditions, the gas temperature remains largely unchanged.

[0173] In preferred embodiments of the invention, the catalytic decomposition of NH3 takes place in a reactor analogous to a primary reformer. For this purpose, the reactor comprises both the NEFI decomposition device according to the invention and the combustion device according to the invention.

[0174] For this purpose, the NH3 decomposition catalyst is preferably arranged in at least one tube through which NH3 flows, more preferably at least two tubes, even more preferably at least three tubes (NED decomposition device). The at least one tube contains the NPh decomposition catalyst. NH3 preferably flows through the at least one tube from top to bottom. In a physically separate combustion chamber, a mixture of NH3 and H2 is preferably combusted together with combustion air as the combustion gas (combustion device). The N2 formed alongside H2 during the catalytic decomposition of NH3 is inert and serves as an additional heat carrier. The combustion heat generated by the combustion process in the combustion chamber of the combustion device is used to heat the NED decomposition device, preferably the tube(s) through which the NH3 to be decomposed is passed.For this purpose, a heat flow is directed from the combustion device into the NPh reduction device.

[0175] In particularly preferred embodiments of the invention, NH3 is preheated before entering the NEfi decomposition device according to the invention. Due to this preheating, the temperature of the NH3 before entering the NEfi decomposition device according to the invention is preferably at least about 600°C, preferably at least about 630°C. The temperature of the NH3 is preferably at most about 850°C, more preferably at most about 820°C. Particularly preferably, the temperature of the NH3 upon entering the NEfi decomposition device according to the invention is about 780°C to 820°C, preferably about 800°C. The NEfi decomposition device according to the invention and the combustion device according to the invention preferably form a reactor designed analogously to a primary reformer. The NH3 decomposition catalyst is preferably nickel-based.In preferred embodiments, the reaction temperature in the NEfi decomposition device, preferably in the at least one tube containing the NEfi decomposition catalyst and through which the NH3 is passed, is preferably about 630°C to about 670°C, preferably about 650°C. In other preferred embodiments, This temperature is approximately 660°C to 700°C, preferably approximately 680°C. The product gas leaves the reactor (the NH3 decomposition device) preferably at a pressure of approximately 15 bar a to approximately 25 bar a, preferably approximately 20 bar a.

[0176] In further particularly preferred embodiments of the invention, the decomposition of NH; takes place in two stages in two successively flowing NEE decomposition devices (see Figure 9). In a pre-reactor (first NH3 decomposition device), only a portion of the NH; is initially decomposed. The remaining decomposition of NH; up to the maximum conversion achieved then takes place in a second NH3 decomposition device. For this purpose, the second NEE decomposition device, together with the combustion device according to the invention, preferably forms a reactor, as described in more detail above, designed analogously to a primary reformer.

[0177] Preferably, the NH3 is preheated before being introduced into the pre-reactor (first NEE decomposition device). The temperature of the NEU after heating and upon entry into the pre-reactor (first NEE decomposition device) is preferably about 620°C to about 680°C, more preferably about 650°C. The preheated NEU then enters the pre-reactor, which contains a NEE decomposition catalyst and in which a catalytic decomposition of NEE to N2 and EE occurs to a certain extent. An intermediate product gas is formed, which still contains significant residual amounts of undecomposed NEE, but also already formed N2 and EE. Due to the endothermic decomposition of NEE, the intermediate product gas cools preferentially.

[0178] Preferably, the conversion of decomposed NEE in the pre-reactor is at most 25%, more preferably at most 20% of the total conversion achieved.

[0179] Preferably, the conversion of decomposed NEE in the pre-reactor is at least 10%, more preferably at least 15% of the total conversion achieved.

[0180] After leaving the pre-reactor, the intermediate gas is preferably reheated before entering the downstream, second NEE decomposition device. The temperature of the intermediate gas after reheating and upon entry into the second NEE decomposition device is preferably approximately 620°C to approximately 680°C, more preferably approximately 650°C. The remaining decomposition of NEE then takes place in the second NEE decomposition device until the total conversion is achieved.

[0181] In this preferred embodiment of the invention, with the same total conversion, the temperature of the intermediate product gas upon entry into the pre-reactor (first NEE decomposition device) and upon entry into the second NEE decomposition device can each be lower than the temperature of the NEE during single-stage decomposition of NEE, i.e., when only a single NEE decomposition device is flowed through. Due to the lower temperature, nitriding of the pipelines occurs to a lesser extent, thereby increasing the service life of the steel that comes into contact with NEE.

[0182] The NHs decomposition catalyst in the first NHs decomposition device (pre-reactor) is preferably the same as in the second NHs decomposition device. combustion gas

[0183] According to the invention, heat is provided by combustion of a combustion gas in a combustion device. For this purpose, the combustion device preferably has one or more burners, preferably at least two burners, more preferably at least three burners.

[0184] The combustion gas preferably contains NH3. The combustion device according to the invention is therefore preferably an NH3 combustion device.

[0185] The combustion gas preferably contains a mixture of H2 and NH3, as this mixture produces a medium flame temperature and exhibits better combustion properties than pure NH3. A suitable mixing ratio of H2 and NH3 also results in less nitrogen oxide formation than in the absence of H2. Combustion air

[0186] Preferably, combustion air is supplied to the combustion device (combustion chamber of the reactor), which air is preferably preheated beforehand in at least one heat exchanger. This at least one heat exchanger is preferably arranged in the flue gas duct, with the combustion air absorbing heat from the flue gas. Thus, excess heat in the flue gas can be used to preheat the combustion air (see Figures 8 and 9, heat exchanger 43 or heat exchanger 45).

[0187] The combustion air is preferably preheated in at least two heat exchangers. These at least two heat exchangers are preferably both arranged in the flue gas duct, with the combustion air each absorbing heat from the flue gas. In preferred embodiments of the invention, a first heat exchanger is arranged in the flue gas duct downstream of the flue gas heat exchanger in the flow direction of the flue gas and preferably serves to preheat the combustion air, with the combustion air absorbing heat from the flue gas (see Figures 8 and 9, heat exchanger 43). A second heat exchanger is preferably arranged in the flue gas duct upstream of the flue gas heat exchanger in the flow direction of the flue gas and preferably serves to further heat the combustion air, with the combustion air again absorbing heat from the flue gas (see Figures 8 and 9, heat exchanger 45).

[0188] Preferably, the combustion air is cleaned by a filter before being fed into the system, compressed to the required pressure with a compressor, and then passed through at least one heat exchanger in the flue gas duct and heated. From there, the heated combustion air flows Combustion air into the combustion device. Shortly before entering the combustion device or within the combustion device, the combustion air is mixed with the combustion gas (preferably NH3 mixed with H2). Product gas - after catalytic decomposition until purification of H2

[0189] The product gas leaves the NH3 decomposition device at a high temperature. To utilize the heat contained in the product gas, at least one heat exchanger is preferably arranged downstream of the NH3 decomposition device in the flow direction of the product gas, through which the product gas flows before the product gas is fed to an H2 purification plant. Preferably, the product gas flows through at least two heat exchangers, more preferably at least three heat exchangers, and even more preferably at least four heat exchangers before the product gas is fed to an H2 purification plant.

[0190] Preferably, the temperature of the product gas at the outlet from the NEL decomposition device is in the range of about 650±100°C, more preferably about 650±50°C.

[0191] Preferably, a product gas heat exchanger is arranged as part of an H2O evaporation device downstream of the NH3 decomposition device in the flow direction of the product gas. This prevents hydrogen embrittlement. The product gas heat exchanger is preferably operatively connected to a steam drum. The H2O evaporation device thus preferably comprises the product gas heat exchanger and the steam drum. Heat contained in the hot product gas leaving the NH3 decomposition device is preferably absorbed by water in the product gas heat exchanger and used to heat or generate steam in the steam drum. The steam drum is preferably fed with demineralized water. The steam is fed via a pipe system into the NH3 evaporation device, where NH3 absorbs heat from the steam and evaporates.After leaving the NEE evaporation device, the NH3 is then further heated and fed to the NEL decomposition device.

[0192] Preferably, the temperature of the product gas at the outlet from the product gas heat exchanger is in the range of about 350±100°C, more preferably about 350±50°C.

[0193] Preferably, a further heat exchanger is arranged downstream of the product gas heat exchanger (H2O evaporation device) in the flow direction of the product gas, which heat exchanger preferably serves to heat the NH3 to the desired temperature at the inlet to the NEL decomposition device or to an intermediate temperature even lower.

[0194] Preferably, the temperature of the product gas at the outlet from the product gas heat exchanger is in the range of approximately 150±100°C, more preferably 150±50°C.

[0195] Since the temperature of the process gas stream is already comparatively low after the product gas has flowed through the product gas heat exchanger (H2O evaporation device) and the further heat exchanger, it is preferred to arrange a preheater for water, which is used in steam generation, downstream of the product gas heat exchanger (H2O evaporation device) in the flow direction of the product gas and preferably also downstream of the further heat exchanger in the flow direction of the product gas (cf. Figures 8 and 9: product gas heat exchanger 26; further heat exchanger 20; preheater 28).

[0196] Preferably, the temperature of the product gas at the outlet from the preheater is in the range of about 90±50°C, more preferably about 90±25°C.

[0197] Preferably, an additional heat exchanger is arranged in the flow direction of the product gas, preferably downstream of the water preheater, which preferably serves to heat water and brings the product gas to the desired temperature for a preferably subsequent purification of H2 (see Figures 8 and 9, process cooler 29). According to the invention, the heat absorbed by the water in this process is preferably used to preheat liquid NH3.

[0198] Preferably, the temperature of the product gas at the outlet from the additional heat exchanger is in the range of about 35±15°C, more preferably about 35±10°C. Product gas - residual amounts of undecomposed NH3

[0199] The recovery of NH3 preferred according to the invention preferably serves to separate non-decomposed NH3 from the product gas and to make it available for further use as combustion gas or recovered reactant.

[0200] NH3 can be separated technically in various ways, e.g. membrane separation, adsorption and condensation, but these processes require high pressures and are therefore energy-intensive.

[0201] In preferred embodiments of the invention, the absorption of NH3 in water can be carried out at process-technical pressures. However, to separate the mixture of NH3 and water by rectification, steam is required as an energy carrier. Since, according to the invention, the combustion gas also comprises NH3, preferably mixed with H2, additional NH3 or H2 must be burned to generate the steam required for rectification, which leads to a reduction in the overall H2 yield.

[0202] If steam is required not only for heating and evaporating NH3, but also for additional purposes, i.e. if there is another consumer of steam, for example an evaporator of a NEfi scrubber, it can be advantageous to use the combination of Product gas heat exchanger and flue gas heat exchanger to be expanded by a third heat exchanger in which water absorbs additional heat from the product gas or the flue gas.

[0203] In other preferred embodiments of the invention, separate recovery of NH3 is omitted. For this purpose, the reaction parameters are selected to achieve the highest possible conversion and thus keep the amount of undecomposed NH3 in the product gas as low as possible. However, this is hardly possible with an economical process control simply by using a high reaction temperature, since the equilibrium temperature would then have to be 900°C or even higher. If separate recovery of NH3 is omitted, small residual amounts of undecomposed NH3 can be separated by other measures by optimizing the process parameters within economically viable limits and with correspondingly good conversion. Thus, according to the invention, the purification of H2 from the product gas is preferably carried out by pressure swing adsorption (PSA).According to the invention, small residual amounts of undecomposed NH3 can be preferably separated during pressure swing adsorption, whereby the recovery of NH3 and the purification of H2 are combined into a single step. Product gas - purification of H2 and separation of residual gas mixture

[0204] The type of H2 purification in the product gas depends on the subsequent technical use of the H2, which determines the quality requirements. Technical-grade H2 can remain relatively impure and, for example, have a purity of approximately 99.7%. However, if H2 is intended for use in fuel cells, a significantly higher purity, such as approximately 99.96%, would be necessary.

[0205] In preferred embodiments of the invention, H2 is purified, for example, by partial condensation, analogous to air separation. However, this requires the use of a compressor to generate the high required inlet pressures of, for example, approximately 230 bar. Furthermore, upstream adsorptive drying is necessary to remove traces of NH3 and H2O. Furthermore, the separation unit itself is required, which is why this concept is cost-intensive in terms of investment and operation.

[0206] In other preferred embodiments of the invention, H2 is purified using membranes. However, H2 and N2 can be separated with only moderate selectivities and yields. Even for separation using membranes, a high inlet pressure must be created, which requires the use of a compressor.

[0207] According to the invention, H2 is particularly preferably purified by pressure swing adsorption (PSA). An adsorptive separation in a pressure swing adsorption device is preferred according to the invention, among other things because it takes place at moderate pressures and additionally achieves high purity of H2, if required > 99.9%, with a yield of H2 of, for example, approximately 85%. As already mentioned, the Pressure swing adsorption also removes residual amounts of NH3 and H2O in the same process step.

[0208] For this purpose, the product gas is preferably cooled to the desired temperature using a process cooler before entering the pressure swing adsorption device. The corresponding amount of heat is preferably absorbed by water in the process cooler (see Figures 8 and 9, process cooler 29). According to the invention, the cooling water heated in this way is preferably used to preheat NH3 in a preheating device in which NH3 absorbs heat from the water (see Figure 7, preheating device 70).

[0209] The cooled product gas is then preferably fed to a pressure swing adsorption device, where the gas mixture is separated under pressure by adsorption. H2 - after purification until storage

[0210] The H2 separated in this way preferably leaves the device for purifying H2, preferably the pressure swing adsorption device, and is preferably brought to an increased pressure using an FEA compressor. The compressed H2 then preferably flows through a heat exchanger, in which cooling water absorbs heat from the compressed H2 (see Figures 8 and 9, compressor 33 and heat exchanger 34).

[0211] In preferred embodiments of the invention, the separated H2 is then brought to a further increased pressure using a second compressor. Preferably, the further compressed H2 then flows through a second heat exchanger, in which cooling water also absorbs heat from the compressed H2 (see Figures 8 and 9, compressor 35 and heat exchanger 36).

[0212] According to the invention, the cooling water heated in this way is preferably used to preheat NH3 in a preheating device in which NH3 absorbs heat from the water (see Figure 7, preheating device 70).

[0213] The compressed H2 is then discharged from the plant at a pressure of, for example, approximately 70 bar and stored, for example, in a suitable pressure vessel or directly used for further purposes. residual gas mixture

[0214] The residual gas mixture remaining after the purification / separation of H2, preferably in the pressure swing adsorption device, typically contains N2, H2O, residual NH3 and H2.

[0215] Preferably, the residual gas mixture is fed to the combustion device so that it can be used to generate combustion heat. flue gas

[0216] The flue gas leaves the combustion device at a high temperature and preferably enters a flue gas duct. To utilize the heat contained in the flue gas, at least one heat exchanger is preferably arranged downstream of the combustion device in the flow direction of the flue gas. The flue gas flows through this heat exchanger before the flue gas is released to the environment, e.g., via a chimney. Preferably, the flue gas flows through at least two heat exchangers, more preferably at least three heat exchangers, and even more preferably at least four heat exchangers before the flue gas is released to the environment.

[0217] In preferred embodiments, the temperature of the flue gas at the outlet from the combustion device is in the range of about 850±100°C, more preferably about 850±50°C.

[0218] In other preferred embodiments, the temperature of the flue gas at the outlet from the combustion device is in the range of about 880±100°C, more preferably about 880±50°C.

[0219] Preferably, a first heat exchanger is arranged in the flue gas duct downstream of the combustion device in the flow direction of the flue gas, which first heat exchanger preferably serves to heat the NH; to the desired temperature at the inlet to the NHs decomposition device.

[0220] Preferably, the temperature of the flue gas at the outlet from the first heat exchanger is in the range of about 700±100°C, more preferably about 700±50°C.

[0221] Preferably, a second heat exchanger is arranged downstream of the first heat exchanger in the flow direction of the flue gas, which second heat exchanger preferably serves to heat the combustion air.

[0222] Preferably, the temperature of the flue gas at the outlet from the second heat exchanger is in the range of about 300±100°C, more preferably about 300±50°C.

[0223] Since the temperature of the flue gas stream is already comparatively low after the flue gas has flowed through the first heat exchanger and the second heat exchanger, it is advantageous to arrange a flue gas heat exchanger for water, which is used to generate steam, downstream of the first heat exchanger in the flow direction of the flue gas and preferably also downstream of the second heat exchanger in the flow direction of the flue gas (see Figures 8 and 9: first heat exchanger: heat exchanger 22; second heat exchanger: heat exchanger 45; flue gas heat exchanger 52).

[0224] The flue gas heat exchanger preferably contributes at least part of the heat for the generation of water vapor.

[0225] Preferably, the temperature of the flue gas at the outlet from the flue gas heat exchanger is in the range of about 250±100°C, more preferably about 250±50°C.

[0226] Preferably, an additional heat exchanger is arranged in the flow direction of the flue gas, preferably downstream of the flue gas heat exchanger, which heat exchanger preferably serves to heat combustion air (see Figures 8 and 9, heat exchanger 43).

[0227] Preferably, the temperature of the flue gas at the outlet from the additional heat exchanger is in the range of about 150±100°C, more preferably about 150±50°C

[0228] In preferred embodiments of the invention, when the catalytic decomposition of the NH3 takes place in two stages in a first NH3 decomposition device and a second NH3 decomposition device, a further heat exchanger is preferably arranged downstream of the first heat exchanger in the flow direction of the flue gas and preferably upstream of the second heat exchanger in the flow direction of the flue gas, which heat exchanger preferably serves to heat the intermediate product gas after leaving the first NH3 decomposition device (pre-reactor) and before entering the second NH3 decomposition device (together with the combustion device analogous to the primary reformer) (see Figure 9, further heat exchanger 67).

[0229] Preferably, the temperature of the flue gas at the outlet from the further heat exchanger is in the range of about 450±100°C, more preferably about 450±50°C. Water or water vapor

[0230] The flue gas leaving the combustion plant represents the largest energy sink in the process after the catalytic decomposition of the NH3 and the evaporation of the NH3. Energy recovery from the flue gas is limited by the fact that temperature differences of less than approximately 45 K between the flue gas and the other process-side streams (reactant for the catalytic decomposition, combustion gas, combustion air, water for steam generation) would require uneconomically large heat exchangers. Therefore, even after all economically viable steps of process-side heat integration, a certain temperature difference remains between the flue gas and the dew point of the water contained in the flue gas.

[0231] According to the invention, this remaining temperature difference is preferably used to generate heated cooling water, which is then used to preheat NH;.

[0232] For the preheating and subsequent evaporation of NH;, the following five configurations are particularly preferred according to the invention: 1. with heat from steam and steam condensate, preferably in countercurrent; 2. additionally with heat from blowdown and from non-evaporated excess boiler feed water; 3. additionally with heat from cooling water, but without using heat from the flue gas and without using heat from the FE compression; the preheating is limited by the existing heat that is extracted from the process stream and used to heat cooling water; 4. additionally with heat from the TE compression and from the water vapor condensate from the NH3 evaporation; namely to produce liquid heated cooling water of higher temperature or liquid heated cooling water of lower temperature; more heat is available in the heated cooling water than can be used in the process, so that the preheating of the NH3 is limited by the minimum temperature difference between the cooling water and the NH3; and / or 5. additionally with heat from the flue gas, but without using heat from the renewable energy compression; namely to generate liquid heated cooling water at a higher temperature or liquid heated cooling water at a lower temperature; here too, more heat is available in the heated cooling water than can be used in the process, so that the preheating of the NH3 is limited by the minimum temperature difference between the cooling water and NH3.

[0233] Demineralized water is preferably fed into the plant as water for steam generation.

[0234] Preferably, the water is preheated via a preheater, through which product gas preferably flows and in which the water absorbs heat from the product gas (see Figures 8 and 9, preheater 28). In the direction of product gas flow, the preheater is preferably arranged downstream of the product gas heat exchanger.

[0235] Preferably, the water after leaving the preheater has a temperature of at least 100°C, more preferably at least 110°C, even more preferably at least 115°C.

[0236] Preferably, the temperature of the water subsequently does not fall below this temperature of at least 100°C, more preferably at least 110°C, even more preferably at least 120°C, before the water in the NEL evaporation device according to the invention releases heat to NH3 for its evaporation.

[0237] Air and other gases dissolved in the water are preferably removed in a degasser.

[0238] Preferably, the water is then passed through the flue gas heat exchanger and heated. The flue gas heat exchanger cools the flue gases from the combustion system in the flue gas duct, using the heat contained in the flue gas to heat the water vapor.

[0239] Preferably, the water after leaving the flue gas heat exchanger has a temperature of at least 180°C, more preferably at least 200°C, even more preferably at least 220°C.

[0240] Preferably, the temperature of the water subsequently does not fall below this temperature of at least 180°C, more preferably at least 200°C, even more preferably at least 220°C, before the Water in the NHs evaporation device according to the invention releases heat to NH3 for its evaporation.

[0241] A specialist recognizes that, depending on the temperature and prevailing pressure conditions, water can be liquid, gaseous (i.e. as water vapor) or as a two-phase system.

[0242] The steam is then preferably fed into a steam drum (see Figures 1-9, steam drum 60).

[0243] From the steam drum, the water is preferentially passed through the product gas heat exchanger, absorbing further heat and then preferentially returned to the steam drum. The product gas heat exchanger is located downstream of the NH3 decomposition unit in the flow direction of the product gas and serves to cool the product gas after it leaves the NH3 decomposition unit. The heat contained in the product gas is also used to heat the steam.

[0244] The hot steam preferentially leaves the steam drum and is preferentially fed into the NH3 evaporator. Condensation of the steam generates heat to evaporate the preheated NH3. After flowing through the NFF evaporator, the steam condensate is preferentially fed to the preheater, which preheats the NH3 so that the heat contained in the steam is used in two stages to heat the NH3. After flowing through the preheater, the steam condensate can be discharged from the plant.

[0245] During steam production, a liquid stream, the so-called "blowdown," is generated at boiling temperature. The "blowdown" is preferentially added to the condensed steam after it leaves the NFE evaporator and before it enters the preheater (Figure 5).

[0246] Since the process provides heat, it is preferable to recover this heat by producing more than the required amount of boiler feedwater, separating this amount before entering the FEO evaporator, and adding it to the blowdown. To this end, the steam leaving the flue gas heat exchanger is preferably split into two partial streams. A first partial stream is preferably introduced into the steam drum. A second partial stream preferably bypasses the steam drum via a bypass and is added to the blowdown (Figure 6).

[0247] In addition to the above-described flow of water or water vapor, further water flows preferably play a role according to the invention.

[0248] Such a preferred water stream according to the invention comprises cooling water, which preferably comes from a process cooler in the flow direction of the product gas upstream of a device for Purification of H2, preferably from a pressure swing adsorption device, where it has previously absorbed heat from the product gas (heated cooling water), or from a heat exchanger of a possible FL compressor, where it has previously absorbed heat from compressed H2 (heated cooling water).

[0249] Another such water stream preferred according to the invention comprises water which is preferably circulated in a circuit and which has previously absorbed heat from the flue gas, for which purpose an additional heat exchanger is preferably in operative connection with another heat exchanger, these being preferably connected to one another via a ring line through which the water is circulated, preferably with a pump. Description of the illustrations

[0250] The invention is explained in more detail below using exemplary embodiments with reference to the figures. Figures 1 to 16 each show, using flow diagrams, preferred embodiments of systems according to the invention, on which preferred embodiments of the process according to the invention can be carried out. Figures 4, 7, 10, and 12-16 each show only a portion of embodiments according to the invention, which are preferred developments of all other figures of embodiments according to the invention.

[0251] A first exemplary flow diagram of a plant according to the invention is explained below with reference to Figure 1. Liquid NH3 is fed from tank 10 into NFL evaporation device 14 and evaporated therein. The heat required for this is obtained by condensing water vapor (see below). From NH3 evaporation device 14, the vaporized NH3 flows into NFL conversion device 24, where the endothermic decomposition of NH3 to N2 and H2 is catalyzed. The heat required to maintain the reaction is generated as combustion heat by burning combustion gas (e.g., NFL / FL / air or CH air) and introduced as a heat flow from combustion device 18 into NFL conversion device 24. The flue gas obtained during combustion flows through flue gas heat exchanger 52, where the heat contained in the flue gas is transferred to water, thereby producing water vapor.After passing through the flue gas heat exchanger 52, the steam is introduced into the steam drum 60 and then via line 63 into the NFL evaporator 14. The NFL is evaporated by the heat released during the condensation of the steam in the NFL evaporator 14 (see above).

[0252] Figure 2 illustrates a variant of the embodiment according to Figure 1, the key difference being that the heat in the product gas, rather than the heat in the flue gas, is used to heat water and steam. The product gas obtained during the catalytic decomposition flows through product gas heat exchanger 26, where the heat contained in the product gas is transferred to water, thereby producing steam. After passing through the product gas heat exchanger 26, the steam is introduced into the steam drum 60 and then via line 63 into the NH3 evaporator 14.

[0253] Figure 3 illustrates a variant of the invention in which both flue gas heat exchanger 52 and product gas heat exchanger 26 are used to heat water and steam, respectively. Steam is passed from flue gas heat exchanger 52 and product gas heat exchanger 26 into steam drum 60. From there, the steam is then introduced into NH3 evaporation device 14 via line 63.

[0254] Figure 4 illustrates a section of a variant according to the invention in which liquid NH; from tank 10 is first fed into preheater 13 and preheated therein by absorbing heat from heated water, before the preheated NH; is fed to the NH3 evaporation device 14. The heated water used is fed as steam condensate via line 64 from the NH3 evaporation device 14 to the preheater 13. In this way, the heat contained in the steam is used in two stages for the heating and subsequent evaporation of NH;. After flowing through the preheater 13, the steam condensate can, for example, be discharged from the system.

[0255] Figure 5 illustrates a variant of the invention that takes into account the fact that a liquid stream also arises as a "blowdown" when steam is generated at boiling temperature. According to this preferred embodiment, the "blowdown" is added to the condensed steam after it leaves the NH3 evaporator 14 and before it enters the preheater 13. In the example shown, the "blowdown" is fed from the steam drum 60 into line 64 via "blowdown" line 68.

[0256] Figure 6 illustrates a variant of the invention in which the heat released during the formation of the blowdown is recovered. In the flue gas heat exchanger 52, more water is heated or more steam is generated than is required for the steam drum 60. The steam leaving the flue gas heat exchanger 52 is then split into two partial streams. A first partial stream is introduced into the steam drum 60. A second partial stream bypasses the steam drum 60 via bypass 69 and is fed into the blowdown line 68.

[0257] Figure 7 illustrates a section of a variant according to the invention in which the yield of H2 is increased by reducing the amount of water vapor produced and instead reintegrating residual heat remaining in the process. This ultimately requires less fuel, which preferably contains H2. According to the variant illustrated in Figure 7, the energy gap in the preheating and evaporation of NH3 is closed by a cooling water-fed preheating device 70. Water for cooling may be required at various points in the plant, for example in process cooler 29 in the flow direction of the product gas upstream of a device for purifying H2, preferably a pressure swing adsorption device 31, or in Heat exchangers 34 or 36, possibly H2 compressors 33 or 35. The water absorbs process heat and is thereby heated. The absorbed heat can be used to preheat liquid NH3.

[0258] Figure 8 illustrates a further variant according to the invention, which is more complex and in which several additional systems are integrated. Liquid NH3, which is present at low temperature and increased pressure, is passed from tank 10 via line 11 by means of pump 12 through preheater 13 and heated, evaporated in NH3 evaporation device 14 and then flows via line 15 to branch 16, where the NFL stream is divided into two partial streams. Starting from branch 16, a first partial stream of the NFL is fed via line 17 to combustion device 18. A second partial stream of NH3, starting from branch 16, is passed via line 19 through heat exchanger 20 and then flows via line 21 through heat exchanger 22, where the NH3 is further heated and then flows via line 23 into NH; decomposition device 24, where the NH; decomposition catalyst is located, so that the catalytic decomposition of NH; takes place there.The NFL decomposition device 24 is preferably flowed through from top to bottom. The heat required to maintain the reaction is generated by heating the NFL decomposition device 24 by burning NH; in the combustion device 18.

[0259] After the decomposition of NFL, the resulting product gas (comprising N2, FL, FL0, and any remaining NFL) flows through product gas heat exchanger 26, then through heat exchanger 20 in crossflow, then through line 27, and for further cooling, through another heat exchanger and preheater 28, which is operated with water, for example. Finally, the product gas is further cooled by a process cooler 29 and then fed via line 30 to a device for purifying FL, preferably a pressure swing adsorption device 31, where the gas mixture is separated under pressure by adsorption.The FL separated in this way leaves the device for purifying FL, preferably the pressure swing adsorption device, 31 via line 32, is brought to an increased pressure via a first FL compressor 33, flows through a heat exchanger 34, a second FL compressor 35 for further pressure increase, a second heat exchanger 36 and is discharged from the plant at a pressure of, for example, about 70 bar via line 37.

[0260] The residual gas mixture remaining in the device for purifying FL, preferably the pressure swing adsorption device 31, after separation of the FL contains N2, FLO, residual NFL and FL and is returned via return line 38 and fed to the combustion device 18 via branching line 39, so that energy contained in the residual gas mixture can be used to generate combustion heat.

[0261] Combustion air for the combustion process in the combustion device 18 is cleaned via filter 40, compressed by compressor 41, passed via line 42 through heat exchanger 43 and heated, then flows via line 44 and through heat exchanger 45, is further heated there and then flows via line 46 and the two branch lines 47 and 48 into combustion device 18, where the combustion air is fed to the partial flow of the NFL supplied via line 17 in order to burn it and thus generate combustion heat.

[0262] The hot flue gas from combustion in combustion device 18 is first cooled via heat exchanger 22, which generates heat for heating the NfL supplied to the NH3 decomposition device 24. The flue gas is then passed through flue gas duct 49 via heat exchanger 45, which preheats the combustion air, and then flows through flue gas denitrification unit 50, which cleans the flue gas of nitrogen oxides (NOx). The flue gas then flows via line 51 through flue gas heat exchanger 52, which generates heat for heating water, and then flows through heat exchanger 43, which also serves to heat the combustion air. The flue gas is then compressed in the end region of flue gas duct 49 by flue gas compressor 53 and exits the plant via chimney 54.

[0263] Water for generating steam is fed in via line 55, passed through preheater 28, and then fed at elevated temperature to deaerator 56, where air and other gases dissolved in the water are removed. By means of pump 57, the water is passed through flue gas heat exchanger 52 via line 58 and heated. Flue gas heat exchanger 52 serves to cool the flue gases from combustion device 18 in flue gas duct 49, whereby the thermal energy contained in the flue gas is used to heat the steam, which then, after passing through flue gas heat exchanger 52, is passed via line 59 into steam drum 60. Water can be passed from steam drum 60 via line 61 through product gas heat exchanger 26, thereby absorbing further thermal energy, before being returned to the steam drum via line 62.The product gas heat exchanger 26 is arranged in the outlet line 25 downstream of the NH3 decomposition device 24 in the flow direction of the product gas and serves to cool the product gas after leaving the NH3 decomposition device 24. The heat obtained can thus be used to generate further water vapor.

[0264] The hot steam generated in steam drum 60 is introduced via line 63 into the upper section of the NH3 evaporator 14. Condensation of the steam generates heat to evaporate the preheated NFL. After flowing through the NH3 evaporator 14, the steam condensate is fed via line 64 to the preheater 13, which preheats the NFL, so that the heat contained in the steam is used in two stages to heat the NFL. After flowing through the preheater 13, the steam condensate can be discharged from the system.

[0265] Figure 9 also illustrates another variant of the invention, which is more complex and in which several additional systems are integrated. Some system components correspond to those in Figure 8 and are therefore not explained in detail again. The heating and evaporation of the NFL are largely unchanged, as are the system components and process steps downstream of the Device for purifying H2, preferably by pressure swing adsorption, after separation of the H2. In contrast to the variant shown in Figure 8, a total of five heat exchangers are arranged in the flue gas duct 49. Here, too, line 21 for heating the NH3 leads from heat exchanger 20 to heat exchanger 22 arranged in the flue gas duct 49. However, after flowing through heat exchanger 22, the NH3 is passed through pre-reactor 65, where the NH3 cools. The gas mixture leaving pre-reactor 65 is then fed via line 66 to heat exchanger 67, which is arranged in the flue gas duct 49 upstream of heat exchanger 22 in the direction of flue gas flow. There, the gas mixture is heated and then introduced via line 23 into NfL reduction device 24.The combustion air for the combustion device 18 is heated as shown in Figure 8, initially by heating via heat exchanger 43 and then by further heating via heat exchanger 45, with both heat exchangers 43 and 45 being arranged in the flue gas duct 49. The heating and evaporation of the water supplied to the steam drum 60 is carried out via preheater 28 and flue gas heat exchanger 52, which is arranged in the flue gas duct 49, as shown in Figure 8. In the variant according to Figure 9, five heat exchangers 67, 22, 45, 52, and 43 are arranged one behind the other in the flue gas duct 49 in the direction of flow of the flue gas.

[0266] One difference in the reaction procedure shown in Figure 9 compared to Figure 8 is that the preheating of the NH3 is limited to lower temperatures, thereby extending the service life of the steel from which the NH3 decomposition device 24 is made, even in contact with NH3. For this purpose, the incoming gas stream is first preheated and then a portion of the catalytic decomposition is carried out in the pre-reactor 65. Subsequently, the gas mixture leaving the pre-reactor 65 is reheated and passed into the NH3 decomposition device 24, where the remaining catalytic decomposition takes place.

[0267] Figure 10 illustrates a section of a variant according to the invention in which an additional heat flow from the system is integrated into the preheating of NH3. Without further measures, the flue gas from the combustion device 18, e.g. in the process according to Figures 8 and 9, still leaves the flue gas duct 49 at an elevated temperature because a relatively high temperature difference is required to preheat the combustion air. According to the variant according to the invention illustrated in Figure 10, this heat in the flue gas is utilized by being absorbed by another water as a heat transfer medium. For this purpose, a further heat exchanger 71 is mounted in the flue gas duct 49, through which water circulates as a heat transfer medium, driven by pump 72.The water is heated in the further heat exchanger 71 and can then serve in the additional heat exchanger 73 as a heat source for NH3, which has advantageously been preheated beforehand by the cooling water in the cooling water-fed preheating device 70.

[0268] Figure 11 schematically illustrates possible sources of heated cooling water 80a to 80d, which is used for preheating and, if necessary, evaporating NH3. According to the invention, only a single one of these sources of heated cooling water 80a to 80d or several or all of these sources of heated cooling water 80a to 80d can be used to preheat and optionally evaporate NH; (embodiments (a) to (d) and any combinations thereof). Liquid NH; enters preheater 13 and absorbs heat from water vapor condensate 76. The thus preheated NH; then enters the NFE evaporator 14 and absorbs heat from the water vapor 75, which in turn condenses to water vapor condensate 76. (a) In the flow direction of the water vapor condensate 76, a water vapor condensate heat exchanger 83 is arranged downstream of the preheater 13, in which cooling water 80a absorbs heat from the water vapor condensate 76. The evaporated NH; leaves the NH3 evaporation device 14 and is split into two partial streams. The combustion device 18 and the NH3 decomposition device 24 exchange heat with each other.A first partial flow of the vaporized NH; is burned as combustion gas in the combustion device 18 and leaves this as flue gas 78, from which heat is subsequently recovered in a flue gas heat integration 81 and reintegrated into the process, (b) In the flow direction of the flue gas, the flue gas heat integration is downstream. 81, a flue gas heat exchanger 52 is arranged, in which cooling water 80b absorbs heat from the flue gas 78. A second partial flow of the vaporized NH; is decomposed in the NH3 decomposition device 24 into product gas 79. In order to be heated to the required temperature, this second partial flow of the vaporized NH; is first heated in a product gas heat integration 82 and subsequently in the flue gas heat integration 81. The hot NH; then enters the NH3 decomposition device 24. After leaving the NH3 decomposition device 24, heat is recovered from the product gas 79 in the product gas heat integration 82 and reintegrated into the process. (c) In the flow direction of the product gas, downstream of the product gas heat integration 82, a process cooler 29 is arranged, in which cooling water 80c absorbs heat from the product gas 78. The product gas leaving the process cooler 29 is then fed to a device for purifying H2, preferably a pressure swing adsorption device 31, and the hydrogen separated in this process is compressed in one or more FE compressors 33, 35. (d) In the flow direction of the hydrogen, one or more heat exchangers 34, 36 are arranged downstream of the one or more FE compressors 33, 35, in which cooling water 80d absorbs heat from the hydrogen 78.

[0269] Figures 12 to 16 are related to each other and also to Figures 4 to 7, which each relate to the preheating of NH3 in preheater 13 and the subsequent evaporation of NH3 in NFE evaporator 14. Figures 12 to 16 each illustrate sections of variants according to the invention. In all of these variants, blowdown and boiler feedwater (both not shown) are preferably combined with the steam condensate after the steam condensate has left the NFE evaporator and before it has been returned to preheater 13.

[0270] Figure 12 illustrates a comparatively simple variant in which liquid NH3 from tank 10 is first fed into preheater 13, where it is preheated by absorbing heat from heated water, before the preheated NH3 is fed to the NH3 evaporator 14. The heated water used is fed as steam condensate via line 64 from the NH3 evaporator 14 to the preheater 13. In this way, the heat contained in the steam is used in two stages for the heating and subsequent evaporation of NH3. After flowing through the preheater 13, the steam condensate can, for example, be discharged from the system.

[0271] Figure 13 illustrates a further development of the variant according to Figure 12, wherein a preheating device 70 is arranged downstream of the compressor 12 and upstream of the preheater 13 in the flow direction of the NH3. In the preheating device 70, NH3 is preheated by absorbing heat from heated water before the preheated NH3 is fed to the preheater 13. The heated water can originate from various sources, preferably from one of the sources for heated cooling water 80a to 80d explained above in connection with Figure 11, i.e. preferably (a) from a steam condensate heat exchanger 83, (b) from a flue gas heat exchanger 52, (c) from a process cooler 29, or (d) from a heat exchanger 34 and / or 36.

[0272] Figure 14 illustrates another development of the variant according to Figure 12, wherein an additional heat exchanger 73 is arranged downstream of the compressor 12 and upstream of the preheater 13 in the flow direction of the NH3, which in turn is preferably operatively connected to a further heat exchanger 71 in the flue gas duct. In the additional heat exchanger 73, NH3 is preheated by absorbing heat from heated water before the preheated NH3 is fed to the preheater 13. The heated water preferably originates from the further heat exchanger 71, in which water absorbs heat from the flue gas in the flue gas duct. In addition, a steam condensate heat exchanger 83 is arranged downstream of the preheater 13 in the flow direction of the steam condensate, in which cooling water absorbs heat from the steam condensate.

[0273] Figure 15 illustrates a further development of the variant according to Figure 13, in which a steam condensate heat exchanger 83 is also arranged in the flow direction of the steam condensate downstream of the preheater 13, in which cooling water absorbs heat from the steam condensate.

[0274] Finally, Figure 16 illustrates a combination of all variants according to Figures 12 to 15. List of reference symbols: tank Line pump Preheater NHs evaporation device Line junction Line Combustion facility Line heat exchanger Line heat exchanger Line NHs decomposition facility Outlet line Product gas heat exchanger Line Preheater Process cooler Line Device for purifying PL, preferably pressure swing adsorption device Line FL compressor heat exchanger PL compressor heat exchanger Hydrogen outlet line Return line branching line Combustion air filter compressor Line heat exchanger Line heat exchanger Line Branch line Branch line Flue gas duct Flue gas denitrification unit 1 Line Flue gas heat exchanger Flue gas compressor Chimney Line for water feed Deaerator Pump 8 Line 9 Line 0 Steam drum 1 Line 2 Line 3 Line 4 Line 5 Pre-reactor 6 Line 7 Additional heat exchanger 8 "B / owdown" line 9 Bypass 0 Preheating device 1 Additional heat exchanger 2 Pump 3 Additional heat exchanger 4 Ring line 5 Steam 6 Steam condensate 7 Combustion gas 8 Flue gas 9 Product gas 0a-d Cooling water 1 Flue gas heat integration 2 Product gas heat integration 3 Steam condensate heat exchanger Examples of implementation

[0275] The following exemplary embodiments serve to explain the invention, but are not to be interpreted in a restrictive manner.

[0276] Heat flows and temperatures were simulated for a model system for different process configurations as illustrated in Figures 12 to 16. The results are summarized in the following table:

[0277] In Examples 4 and 5, heat from the cooling water of the Fh compressor is transferred to the ammonia in cooling water preheater 70.

Claims

Patent claims:

1. A plant for the production of H2 by catalytic decomposition of NH3 comprising - a combustion device (18) for burning a combustion gas to produce combustion heat and flue gas; - an NH3 evaporation device (14) for evaporating liquid NH3 by absorbing heat from heated water; - in the flow direction of the NH3 downstream of the NHs evaporation device (14), an NHs decomposition device (24) for the catalytic decomposition of evaporated NH3 by absorbing combustion heat generated in the combustion device (18) and producing a product gas comprising H2 and N2; - in the flow direction of the flue gas downstream of the combustion device (18), a flue gas heat exchanger (52) for heating water by absorbing heat from the flue gas; and / or in the flow direction of the product gas downstream of the NFh decomposition device (24), a product gas heat exchanger (26) for heating water by absorbing heat from the product gas; and - a line (63) for the heated water from the flue gas heat exchanger (52) and / or from the product gas heat exchanger (26) to the NHs evaporation device (14).

2. The plant according to claim 1, wherein the plant is designed for a throughput based on H2 of at least 500 mol-h 1 is designed.

3. The plant according to claim 1 or 2, wherein the plant comprises a tank (10) for liquid NH3, which has a volume of at least 50 m 3 has.

4. The plant according to any one of the preceding claims, wherein the NFh decomposition device (24) comprises at least three catalyst beds, each comprising NH3 decomposition catalyst.

5. The plant according to any one of the preceding claims, wherein the NFh reduction device comprises at least one catalyst bed comprising NFh reduction catalyst, the length of the catalyst bed in the flow direction for NH3 being at least 1.0 m.

6. The plant according to one of the preceding claims, wherein the combustion device (18) comprises at least three burners for combustion of the combustion gas.

7. The plant according to one of the preceding claims, wherein the flue gas heat exchanger (52) and / or the product gas heat exchanger (26) is a tube heat exchanger or tube bundle heat exchanger.

8. The plant according to one of the preceding claims, wherein the plant comprises a preheater (13) for heating NH3 upstream of the NH3 evaporator (14) in the flow direction of the NH3; by absorbing heat from water exiting the NH3 evaporator (14).

9. The plant according to any one of the preceding claims, wherein the plant comprises a device for purifying H2(31).

10. The plant according to claim 9, wherein the device for purifying H2 is a pressure swing adsorption device (31).

11. The plant according to one of the preceding claims, wherein the plant comprises a preheating device (70) for preheating NH; by absorbing heat from heated cooling water in the flow direction of the NH; upstream of the NH; evaporation device (14), preferably upstream of the preheater (13) that may be present.

12. The plant according to claim 11, wherein the heated cooling water exits from a process cooler (29) in the flow direction of the product gas upstream of the device for purifying H2, preferably pressure swing adsorption device (31).

13. The system according to claim 11 or 12, wherein the heated cooling water exits a heat exchanger (34) of an H2 compressor (33).

14. The plant according to one of claims 11 to 13, wherein the heated cooling water exits from a steam condensate heat exchanger (83) in the flow direction of the steam condensate downstream of the NEE evaporation device (14), preferably downstream of the preheater (13) if present.

15. The system according to any one of the preceding claims, wherein the system - in the flow direction of the NH; upstream of the NH; evaporation device (14), preferably upstream of the possibly present preheater (13), preferably downstream of the possibly present preheating device (70), an additional heat exchanger (73) for preheating NH; by absorbing heat from water; and - in the flow direction of the flue gas downstream of the flue gas heat exchanger (52) comprises a further heat exchanger (71) for heating the water by absorbing heat from the flue gas.

16. The system according to claim 15, wherein the additional heat exchanger (73) and the further heat exchanger (71) are connected to each other via a ring line (74) for circulating the water.

17. The system according to any one of the preceding claims, wherein the system comprises at least two heat exchangers; preferably - the product gas heat exchanger (26) and the flue gas heat exchanger (52); or - the flue gas heat exchanger (52) and the further heat exchanger (71); or - the preheater (13) and the product gas heat exchanger (26); or - the preheater (13) and the flue gas heat exchanger (52).

18. The system according to any one of the preceding claims, wherein the system comprises at least three heat exchangers; preferably - the preheater (13), the product gas heat exchanger (26) and the flue gas heat exchanger (52); or - the preheating device (70), the preheater (13) and the product gas heat exchanger (26); or - the preheating device (70), the preheater (13) and the flue gas heat exchanger (52).

19. The plant according to one of the preceding claims, wherein the plant comprises at least four heat exchangers; preferably the preheating device (70), the preheater (13), the product gas heat exchanger (26) and the flue gas heat exchanger (52).

20. The plant according to one of the preceding claims, wherein the plant comprises at least five heat exchangers; preferably the preheating device (70), the additional heat exchanger (73), the preheater (13), the product gas heat exchanger (26), and the flue gas heat exchanger (52).

21. The plant according to one of the preceding claims, wherein the plant comprises a return line (38) and a branching line (39) for a residual gas mixture remaining after separation of the H2 from the device for purifying H2, preferably pressure swing adsorption device (31), to the combustion device (18).

22. Use of a plant according to one of the preceding claims for the production of H2.

23. A process for producing H2 by catalytic decomposition of NH3 comprising the steps: (a) burning a combustion gas to produce heat of combustion and flue gas; (e) evaporation of liquid NH3 by absorption of heat from heated water; (f) catalytic decomposition of NH3 vaporized in step (e) by absorbing heat of combustion generated in step (a) and producing a product gas comprising H2 and N2; and (g) heating water by absorbing heat from the flue gas generated in step (a) and / or from the product gas generated in step (f); and using the heated water in step (e).

24. The process according to claim 23, wherein in step (f) a throughput based on H2 of at least 500 mobh 1 is achieved.

25. The method according to claim 23 or 24, wherein in step (e) the liquid NH3 is supplied from a tank having a volume of at least 50 m 3 is taken.

26. The process according to any one of claims 23 to 25, wherein in step (f) the catalytic decomposition of NH3 takes place on at least three catalyst beds, each comprising NfL decomposition catalyst.

27. The process according to any one of claims 23 to 26, wherein in step (f) the catalytic decomposition is carried out on at least one catalyst bed comprising NfL decomposition catalyst, the length of the catalyst bed in the flow direction for NH3 being at least 1.0 m.

28. The method according to any one of claims 23 to 27, wherein in step (a) the combustion of the combustion gas is carried out by means of at least three burners.

29. The method according to any one of claims 23 to 28, wherein the heating in step (g) is carried out in a heat exchanger selected from tube heat exchangers and tube bundle heat exchangers.

30. The method according to any one of claims 23 to 29, wherein the method comprises the additional step: (d) Heating of NH by absorbing heat from water obtained by step (e).

31. The method according to one of claims 23 to 30, wherein a purification of H2 takes place in a device for the purification of H2, preferably a pressure swing adsorption device (31).

32. The method according to any one of claims 23 to 30, wherein the method comprises the additional step: (b) Preheating of NH3 by absorbing heat from heated cooling water.

33. The process according to claim 26, wherein the heated cooling water has previously absorbed heat from the product gas before carrying out the purification of H2, preferably pressure swing adsorption, and / or from EE after its compression.

34. The method according to any one of claims 23 to 33, wherein the method comprises the additional step: (c) preheating NH3 by absorbing heat from water; and heating the water thus obtained by absorbing heat from the flue gas.

35. The method of claim 33, wherein the water is circulated.

36. The method according to one of claims 23 to 35, wherein a residual gas mixture remaining in the device for purifying H2, preferably the pressure swing adsorption device (31), after separation of the H2 is returned via a return line (38) and fed to the combustion device (18) via a branching line (39).

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