Method for operating a metallurgical plant

Abstract

A method for operating a metallurgical plant comprising an ammonia storage installation, an ammonia using device, and a metallurgical processing device, the method comprising the steps of (a) conveying a first stream of ammonia from the ammonia storage installation toward the ammonia using device, (b) collecting a second stream of fluid, preferably from an installation of the metallurgical plant, (c) extracting cold from the first stream and transferring extracted cold at least in part to the second stream to cool the second stream and / or extracting heat from the second stream and transferring extracted heat at least in part to the first stream, preferably to heat and / or gasify the first stream, wherein the method further comprises the steps of (d) chemically and / or thermally transforming ammonia from the first stream in the ammonia using device to produce a third stream, and (e) feeding the third stream to the metallurgical processing device.

Description

METHOD FOR OPERATING A METALLURGICAL PLANTTechnical Field

[0001] The present invention generally relates to a method for operating a metallurgical plant, such as an ironmaking and / or steelmaking plant, and more particularly to a method for improving utilization of resources while reducing CO2 emissions.Background Art

[0002] Industrial processes contribute significantly to global CO2 emissions and the current metal manufacturing processes, such as the iron and steel manufacturing process, are very energy and carbon intensive. With the Paris Agreement and near- global consensus on the need for action on emissions, it is imperative that each industrial sector looks into the development of solutions towards improving energy efficiency and decreasing CO2 output.

[0003] In the iron and steel manufacturing, the Blast Furnace - Basic Oxygen Furnace remains the most common route for steel manufacturing allowing for the largest versatility of steel grades. One technology developed to reduce the carbon footprint is to feed to the furnace a reducing gas, mainly comprising hydrogen and carbon monoxide (syngas).

[0004] Another technology developed to reduce the carbon footprint during steel production is the iron ore direct reduction process. Although annual direct reduction iron production remains small compared to the production of blast furnace pig iron, it is indeed very attractive for its considerably lower CO2 emissions, which are 40 to 80 % lower for the direct reduction - electric arc furnace (EAF) route, compared to the blast furnace - basic oxygen furnace route, depending on process parameters.

[0005] In all cases, in the context of the reduction of CO2 emissions, considerable efforts are also being made to reduce the usage of carbonaceous fuels as feedstock for reducing gas production, and there is a growing need to have readily available essentially pure H2 produced on-site for injection (i.e. feeding) into either one of a shaft furnace, a basic oxygen furnace, an electric arc furnace, or any ironmaking or steelmaking apparatus demanding a reducing gas.

[0006] The situation is similar in other, non (pure) iron metal manufacturing processes (such as e.g. in ferro alloy production as FeCr or FeSi production), in that further efforts have to be made in reducing CO2 emissions.

[0007] It has been proposed to use ammonia as CCh-lean hydrogen carrier for producing a reducing gas with high hydrogen content, and limited to zero CO2- emissions during production. The delivery of ammonia as CO2-lean hydrogen carrier typically occurs in the form of refrigerated (i.e. cold) liquid ammonia (-33 °C or below, no pressurization) or pressurized ammonia (10 to 15 bar, ambient temperature), and can be performed on tanker ships, trains or trucks to reach the final destination were hydrogen is needed, for which the direct hydrogen transport would have significantly higher transport cost for a long distance supply chain where hydrogen pipelines may not be feasible.

[0008] However, the application of ammonia typically involves the heating and evaporation of the liquid stored at below -33 °C and 1 atm, or the depressurizing of the gaseous ammonia stored at 10-15 bar. The depressurizing causes a significant drop of gas temperature, possibly to temperatures below about 0 °C depending on the difference of pressures, which thus also requires heating. In conclusion, the application of ammonia as CO2-lean hydrogen carrier always requires heating, i.e. use of resources and energy to increase its temperature.

[0009] Thus, there is still a need for improving the operating methods of a metallurgical plant using ammonia as a hydrogen carrier in terms resources and energy consumption.Technical Problem

[0010] It is thus an object of the present invention to provide an improved method of operating a metallurgical plant with improved use of resources and energy and concomitantly reduced CCh-emisions.

[0011] This object is achieved by a method as claimed in claim 1 and a metallurgical plant as claimed in claim 23.General Description of the Invention

[0012] In a first aspect, the present invention provides a method for operating a metallurgical plant comprising an ammonia storage installation, an ammonia usingdevice, and a metallurgical processing device, the method comprising the (ordered) steps of a) conveying a first stream of ammonia from the ammonia storage installation toward the ammonia using device, b) collecting a second stream of fluid, preferably from an installation of the metallurgical plant, c) extracting cold from the first stream and transferring extracted cold at least in part to the second stream to cool the second stream and / or extracting heat from the second stream, and transferring extracted heat at least in part to the first stream, preferably to heat and / or gasify the first stream.

[0013] According to the invention, the method further comprises the (ordered) steps of d) chemically and / or thermally transforming ammonia from the first stream in the ammonia using device to produce a third stream, and e) feeding the third stream to the metallurgical processing device.

[0014] The ammonia storage installation can be of any kind and it is configured to store ammonia either as liquid or gaseous ammonia. The first stream is a cold stream in that it has a temperature below ambient temperature, such as below 10 °C, preferably below 5 °C, below 0 °C or below -20 °C or even below -33 °C. In preferred embodiments, the ammonia storage installation comprises a liquid ammonia storage tank and / or the first stream is a stream of liquid ammonia.

[0015] The fluid of the second stream may be of any kind as long as it comprises heat, either as sensible heat (i.e. the fluid being hot) or as latent heat (i.e. the fluid being able to undergo an exothermic phase transition). Preferably, the second stream has a temperature above (i.e. higher than) the temperature of the first stream, preferably a temperature of at least 10 °C, more preferably at least 20 °C or at least 25 °C, even more preferably at least 40 °C and heat is extracted as sensible heat and / or the second stream of fluid is a stream of gas and heat is extracted as latent heat of any phase transition such as e.g. condensation heat of a gas to liquid phase transition of the second stream.

[0016] In a second aspect, the present invention also provides a metallurgical plant comprising an ammonia storage installation, an ammonia using device and a metallurgical processing device, wherein:- the ammonia using device is in fluidic downstream communication with the ammonia storage installation and in fluidic upstream communication with the metallurgical processing device;- the ammonia using device is configured for chemically transforming ammonia of a first stream from the ammonia storage installation to produce a third stream;- the plant further comprising means configured to extract cold from the first stream (stream of ammonia) and transfer it at least in part to a second stream of fluid, wherein the means configured to extract cold are arranged between the ammonia storage installation and the ammonia using device in fluidic communication therewith.

[0017] The metallurgical plant according to the second aspect is preferably configured for implementing the method according to the first aspect.

[0018] Technical features, explanations and advantages disclosed in relation to the herein disclosed method for operating a metallurgical plant apply mutatis mutandis to the present metallurgical plant.

[0019] The metallurgical plant can be any metal processing plant, and the metallurgical processing device can be any device used for the preparation of iron ore for the steel production process, such as sinter and / or pellet plant, for the production of steel raw material, for the production of steel and for steel processing. Preferably the metallurgical plant is an ironmaking and / or steelmaking plant and may include the preparation of the ore for the ironmaking process and the metallurgical processing device is a metal oxide reducing device or a steel processing device or an iron ore preparation device. In the present context, a metal oxide (metal ore) reducing device reduces a metal oxide or metal ore to the corresponding metal, such as iron oxide, copper oxide, ... and / or produces a ferro alloy such as FeCr, FeSi. A steel processing device may be e.g. a reheating furnace, an annealing furnace, .... An iron ore preparation device may be e.g. a sinter plant, a pellet plant, a briquetting plant or any other agglomeration plant.

[0020] The present invention advantageously provides a method for operating a metallurgical plant, and such a plant, with an advantageous integration of ammonia by taking advantage of the cold energy from heating and evaporation of ammonia in order to reduce cold, and in particular cooling water, requirements in the metallurgical (preferably steelmaking) process. In other words, the present invention provides a method (and plant) where ammonia is used as a feedstock (e.g. of energy and / or of hydrogen and / or of a mix of hydrogen and nitrogen), and which benefits more from heated or evaporated ammonia than from unheated gaseous or liquid ammonia.

[0021] Advantageously, the present method allows to reduce CO2 emissions of the metallurgical plant (e.g. steel plant) by using the CCh-lean (preferably green) cold energy from the (imported) ammonia to reduce the local energy requirement, which might have a higher carbon footprint, and thus in consequence reduce the carbon footprint of the metallurgical plant.

[0022] On a large scale, e.g. in metallurgical plants, ammonia is typically stored as a liquid at below -33 °C and atmospheric pressure, to minimize scaling challenge of high-pressure storage (i.e. challenge occurring due to the storage of bigger volumes of gaseous ammonia). However, upon utilization, i.e. endothermic chemical transformation to produce hydrogen H2 or other utilizations, ammonia needs to be heated, i.e. to give away its cold. In other words, the application of ammonia as CO2- lean hydrogen carrier is a novel source of freezing cold, requiring heating before the hydrogen carrier can become efficiently usable.

[0023] The ammonia using device may be any kind of device or reactor configured for chemically or thermally transforming, preferably combusting or cracking, ammonia.

[0024] Extracting cold from the first stream of (preferably liquid) ammonia prior to its feeding to the ammonia using device advantageously alleviates energy requirements for its chemical (and / or thermal) transformation (preferably cracking / reforming or combustion), thereby reducing costs and CO2-emissions.

[0025] Another advantage is that cold extracted from the first stream (stream of ammonia) is collected and used in the metallurgical plant, i.e. is not lost nor wasted. In other words, the cooling capacity of ammonia is beneficial and can be exploited to replace, at least partially, cooling duty from other cooling media (cooling water, coolinggas or refrigerant). Preferably, the cooling capacity of the ammonia can at least partially reduce the dimensions needed for a cooling tower of the metallurgical plant, or fully substitute it. Further advantageously, cooling water requirements of the metallurgical plant would be reduced, thus reducing water consumption, which is of particular interest when water is scarce and / or rivers levels are low.

[0026] Typical cold requirements for blast furnace operation are of about 500 MJ / t HM. Thus, for a typical blast furnace producing 300 tons per hour (tph), this means about 40 MW or about 60 m3 / h of water evaporation in the cooling tower. For slag granulation, we have approximately 0,8 m3of water consumption per ton of slag produced. Supposing a slag rate of 300 kg / t HM and a production of 300 tph, this leads to a reduced cooling water requirement of 72 m3 / h or 50 MW cooling power.

[0027] In some preferred embodiments, the metallurgical processing device comprises a metal oxide reducing device, the ammonia using device comprises an ammonia cracker, the third stream produced in step d) is a stream of hydrogen-rich gas, and the third stream is fed to the metal oxide reducing device. In the ammonia using device, the following endothermic reaction occurs, preferably thermally and / or catalytically:2 NH3(g) - N2(g) + 3 H2(g)

[0028] Preferably, at least 20 vol.-%, more preferably at least 40 vol.-%, at least 50 vol.-% or even at least 60 vol.-%, 70 vol.-% or 80 vol.-%, of the ammonia fed to the ammonia reformer / cracker is cracked.

[0029] The ammonia using device may be a simple ammonia heating device in which the ammonia is heated to such temperature levels where at least 20 vol.-% of the ammonia is cracked simply by the thermal gas phase cracking reaction.

[0030] Advantageously, such embodiments provide for the downstream usage of ammonia as hydrogen carrier (i.e. chemical transformation of ammonia in the ammonia using device to produce a hydrogen-rich gas) which - with respect to conventional, ammonia based refrigerating systems - eliminates the need to regenerate expanded / heated gaseous ammonia back to cold liquid ammonia, alleviating the need for a refrigeration and / or compression installation.

[0031] That is to say, preferred embodiments are based on the downstream usage of otherwise lost cold from ammonia upon H2production and / or for energysupply, respectively downstream usage of refrigerating ammonia to produce H2 and / or as energy supply instead of recycling it as a refrigerant. Such a concept is all the more interesting when considering metallurgical decarbonization projects, where the application of CCh-lean hydrogen (such as e.g. green hydrogen, blue hydrogen or pink hydrogen) or ammonia can save significant amounts of CO2 emissions. Indeed, in C02-lean metal making, such as in particular in C02-lean steel making, C02-lean hydrogen produced e.g. from ammonia may replace a significant amount of fossil carbon used as energy or reductant quite easily. Ammonia may thus be used as hydrogen carrier to reduce CO2 emissions.

[0032] Further advantageously, ammonia may be used as hydrogen carrier to reduce CO2-lean energy transport costs. Indeed, the delivery of CO2-lean hydrogen in the form of ammonia (either liquid or gaseous), e.g. on trains or trucks can save significant transport costs and CO2 emissions due to its transport for a long distance supply chain where hydrogen pipeline may not be feasible.

[0033] Yet further advantageously, according to some preferred embodiments of the present invention, hydrogen H2 is directly produced on-site, i.e. locally produced where it is needed and could be directly of use for operating a metal oxide reducing plant, such as in particular an ironmaking and / or steelmaking plant, thereby (further) alleviating the technical challenges and need for H2 storage and especially transport.

[0034] Ammonia cracked in the ammonia using device (i.e. ammonia cracker) may be directly fed as a third stream I stream of cracked ammonia to the metal oxide reducing device. That is to say, the (third) stream fed to the metallurgical processing device comprises (non-negligible amounts of) hydrogen H2 and dinitrogen N2. Alternatively, hydrogen from the stream of cracked ammonia (i.e. the third stream) may be purified before being fed to the metallurgical processing device.

[0035] In the present text, the term “ammonia” refers to a gas or a liquid mainly comprising NH3, i.e. comprising at least 70 vol.-%, preferably at least 80 vol.-%, more preferably 90 vol.-%, even more preferably at least 95 vol.-% or at least 98 vol.-% of NH3.

[0036] In the present text, the term “hydrogen” refers to molecular hydrogen H2, and a hydrogen-rich gas refers to a gas comprising at least 40 vol.-%, preferably atleast 50 vol.-%, more preferably 60 vol%, even more preferably at least 70 vol.-%, even more preferably at least 80 vol.-%, at least 90 vol.-% or at least 95 vol.-% of H2.

[0037] According to the same or other embodiments, the metallurgical processing device comprises a plant unit such as a reheating furnace, an annealing furnace, a sinter plant and / or a pellet plant, ..., and the ammonia using device comprises a burner (preferably of the plant unit such as the reheating furnace, the annealing furnace, the sinter plant, the pellet plant, ...) to combust the first stream (i.e. stream of ammonia) so that the third stream produced in step d) is a hot stream heating the plant unit such as reheating furnace, the annealing furnace, the sinter furnace, the pellet furnace, ...

[0038] The burner may be an ammonia burner (i.e. burning substantially pure ammonia) or a burner burning ammonia added to its (conventional) fuel mix. In the burner, the following reaction occurs:4 NH3+3 O22 N2+ 6 H2O

[0039] It is also possible that the ammonia burner will burn a mixture of ammonia, cracked ammonia and / or its (conventional) fuel mix.

[0040] In embodiments comprising both an ammonia cracker and a plant unit with a burner, such as e.g. a reheating furnace, an annealing furnace, a sinter plant and / or a pellet plant, the cracker might be specifically dedicated to the plant unit where the burner is installed (reheating furnace, annealing furnace, sinter plant, pellet plant, ...) or it might also come from a central ammonia cracker which supplies the cracked ammonia to different plant units and possibly also to the metallurgical plant for ore reduction.

[0041] Burning of CO2 lean ammonia to produce heat will further help to reduce the CO2 emissions of the metallurgical plant without requiring hydrogen storage, or at least having strongly reduced requirements for hydrogen storage. The utilization of a mixture of ammonia with cracked ammonia and / or (conventional) fuel might be necessary to allow for low NOx combustion. In fact, the burning of uncracked ammonia might lead to high NOx emissions requiring the installation of a NOx removal device in the flue gas of the burner prior to release to the atmosphere. Preferably the energy not coming from ammonia in the burner fuel mix (i.e. mixture fed to the burner) is above5 %, more preferably above 10 % or even more preferably above 20 % or even above 30 %.

[0042] As known in the field, net zero emissions e.g. in the steelmaking industry for example would most probably only be achievable through carbon capture, as a minimum amount of carbon is always required in basic oxygen furnace or electric arc furnace, even if the reduction and smelting is fully done by hydrogen and electrical energy.

[0043] Consequently, metallurgical decarbonization projects would also envisage some sort of carbon capture and storage or utilization method. No matter the capture technology used, any storage or downstream utilization of captured CO2 requires high purity CO2. In addition to conventional processing steps, such as e.g. condensation and sulphur removal, NOx removal, particulate matter removal, ..., such purity levels typically are only possible by applying a refrigerated liquefaction step in which CO2 is liquefied either by compression, intercooling and subsequent expansion of the CO2 itself, or by transferring its condensation heat to another cold refrigerant media. The obtained liquid CO2 (with or without having been submitted to additional process and / or cleaning steps) can then be used for transport, downstream usage or storage, either as liquid CO2 itself or as reheated gaseous CO2.

[0044] Accordingly, the second stream can also be the complete flue gas stream containing the CO2 and also the vapor resulting from the combustion process. The cold from the first stream would at least be partially used to condense the vapor contained in the gas stream from which in the next step CO2 is removed.

[0045] Accordingly, in most preferred embodiments, the second stream is a CO2-rich stream and CO2 is purified (e.g. extracted / separated), preferably by liquefaction, from the second stream by the cold extracted from the first stream, in a CO2-capture plant or in a CC -separation plant. In other words, the CO2-rich stream is purified by a process comprising a liquefaction step, wherein the cooling energy required for the liquefaction is provided, at least in part, by the cold extracted from the ammonia.

[0046] The extracted, and preferably liquified, CO2 has a purity corresponding to industrial standards suitable for CC -storage. In embodiments, extracted CO2 has a purity of at least 95 %, preferably at least 98 % or even at least 99 %.

[0047] This embodiment advantageously synergistically reduces consumption of CO2 abatement utility for ironmaking and / or steelmaking plants using carbon capture in regions with poor access to renewable energy. Resources needed for refrigeration systems, such as e.g. electrical power, cooling water or refrigerants, can be reduced thanks to the cold extracted from the ammonia. This way, scope 2 emissions stemming from local electrical power generation can also be reduced, which are reasoned to be high for industrial regions with poor access to renewable energy, which need to import CCh-lean H2 as ammonia in the first place.

[0048] In other words, usage of cooling capacity from ammonia can reduce CO2 capture system costs below best practice, by reducing cooling water and local energy (e.g. electricity) consumption and rendering partially or completely obsolete compressor-expansion steps.

[0049] The combination and carbon capture synergistically attain a reduced and possibly net zero emission concept with a reduced CO2 abatement cost thanks to the integration of CO2-lean ammonia utilization with carbon capture.

[0050] The proposed integration concept would beneficially use cold extracted from ammonia to liquefy CO2 (potentially up to storage or utilization compliant standards, albeit it is within the scope of the present invention to use the cold from the first stream of ammonia to reach almost compliant standard and use another source of cold to reach standards) and / or condense vapors comprising CO2, and also beneficially use the condensation heat of CO2 to prepare ammonia for utilization (i.e. heat ammonia prior to its cracking to produce a hydrogen H2 rich stream and / or prior to its combustion in burners to produce a hot stream heating a plant unit). This is especially beneficial when considering the thermodynamic properties of ammonia and CO2 condensation / evaporation in the context of decarbonization projects including both carbon capture and the usage of ammonia as hydrogen carrier. As the target in such projects is to minimize CO2 emissions with high usage rates of CO2-lean ammonia, it is essentially guaranteed that there is an excess of low temperature cold from ammonia compared to the requirement for CO2 liquefaction. Not only would the total quantity of ammonia to be heated vastly out scale the quantity of CO2 to be liquefied, but also the liquid to gas phase change enthalpy for ammonia at 23 kJ / mol is significantly more than that of CO2 at 15 kJ / mol. Thus, there is a thermodynamic and project context derived beneficial situation for an efficient cold integration.

[0051] Indeed, ammonia refrigeration systems can achieve refrigerant temperatures of down to -60 °C, which is much colder than what is required to liquefy CO2. The usage of cold below -33 °C can further advantageously reduce pressure requirement of the CO2 liquefaction step. Lower pressure system may save costs, especially when upscaling due to ease of tightness and reduced compressor requirements.

[0052] Furthermore, large-scale CO2 capture is done in-situ, by directly liquefying the CO2 containing gas. The process involves compression, cooling and expansion of the CO2 containing gas itself. External indirect refrigeration of CO2 using the compression, cooling and expansion of a refrigerant does exist, but is technically disfavored due to refrigerant sourcing costs, refrigerant leakage risk and refrigerant regeneration costs. Not only is ammonia an excellent choice for a refrigerant media in general, but especially in the present invention. By colocation of gaseous ammonia consumer (i.e. chemical transformation of ammonia replacing the need for its regeneration) and CO2 capture unit, the disadvantage of refrigerant regeneration is eliminated, as fresh ammonia can be drawn from storage, without the need to reliquefy gaseous ammonia at the end of the refrigeration cycle. Also, the refrigerant supply does not pose any additional challenge, as a supply chain would need to be established for the ammonia usage anyways. Thus, ammonia integration as refrigerant and as hydrogen carrier, enables unique synergies with indirect CO2 liquefaction, reducing cost and utility consumption, potentially below current state of the art direct CO2 liquefaction technologies. Moreover, since the equipment and energy requirements are reduced when using cold from ammonia and also due to the fact that large quantities of cold from ammonia are available, even gas streams with CO2 concentrations not usually considered for treatment, such as streams with less than 50 vol-% or even less than 40 vol.-% can advantageously be treated with the present inventive method and / or plant.

[0053] In other words, the present invention thus advantageously uses NH3 both as CO2-lean H2 carrier and CO2-lean cold carrier to minimize CO2 emissions of a metallurgical plant, by significantly improving the metalmaking process with CO2-lean H2 and / or energy, and / or significantly improving the carbon capture process with CO2- lean cold transported by CO2-lean NH3 as a carrier molecule and / or reducing cooling water and cooling energy requirements. The demand on local CO2-lean H2 and cold,usually embodied in the form of CCh-lean electricity and water can thus be drastically reduced to lower the environmental resource strain of the metalmaking plant in addition to the lower CO2 emissions. In this way, the C02-lean electricity and cold demand is virtually relocated to the production site of C02-lean NH3, which shall be more abundant in said resources.

[0054] More specifically, CO2-lean H2 produced from ammonia is used to replace fossil carbon in the metal oxide reducing industry, in particular an iron and steel making process, to reduce process related CO2 emissions, whilst the cold of ammonia is used to refrigerate a CO2 containing flue gas to achieve efficient carbon capture through liquefaction for remaining hard-to-abate last mile emissions of the low CO2 footprint metallurgical plant, such as a steelmaking plant.

[0055] The CO2-rich stream may be generated (directly or indirectly) by any kind of CO2-generating device, i.e. the CO2-generating device may be any kind of industrial installation, either as part of the metallurgical plant or as part of another industrial plant, the CO2-rich gas being imported to the metallurgical plant. It is however preferred that the CO2-rich stream be generated (i.e. the CO2 be emitted) on site of the metallurgical plant so as not to input further costs and / or environmental strains for the transport of a CO2-rich gas, and also in order to further reduce CO2-emissions of the metallurgical plant. In other words, according to preferred embodiments, the CO2-rich stream is generated by at least one of the ammonia using device, the metallurgical processing device (such as e.g. a metal oxide reduction device), the ammonia heating system and a powerplant (typically located inside a steelmaking plant or next to it), and / or other furnaces used within the metallurgical plant, such as pellet furnace, reheating furnace, sinter furnace, ....

[0056] It shall be noted that any appropriate technology may be used to extract cold form the first stream and transfer it to the second stream and / or extract heat from the second stream and transfer it to the first stream. In embodiments, heat of the second stream and / or cold of the first stream is extracted by direct heat exchange between the first and second streams, for example, in a heat exchanger and / or an evaporative cooler. In other words, the first stream may flow through a cold giving (or heat taking) side of a heat exchanger while the second stream flows through a heat giving (or cold taking) side of the heat exchanger. In this connection, one may use any appropriate type of heat exchanger in combination with a heat exchange fluid circuit.A possible type of heat exchange system is the so-called “heat pipe” (either of the straight or loop type), where the evaporator section would be arranged on the side of the first stream and the condenser section on the side of the second stream.

[0057] In embodiments, ammonia may be injected into a flue gas at high temperatures (e.g. above 100 °C, preferably above 150 °C or 200 °C) to cool down the flue gas to carbon capture requirements while advantageously simultaneously reducing the formation of NOx, beneficially increasing captured CO2 quality and reducing tail gas treatment requirement.

[0058] Preferably, the heat / cold exchange occurs in an ammonia based- refrigeration system, i.e. cold from the first stream is directly transferred to the second stream in an ammonia-based refrigeration system. Ammonia is the preferred refrigerant in many industrial fields, including metallurgy, because it occurs naturally and is cheap, any leakage can be easily detected due to its strong sour smell and the flammability is in the visible spectrum (albeit less visible than hydrocarbon flames, NH3 flames are more visible than H2 flames). Additionally, ozone depletion rating of ammonia is zero, and its global warming potential is below 1 , which is hundreds or thousands less than other refrigerants.

[0059] It shall be noted that the amount of cold available from the first stream vastly outnumbers the requirement for CO2 capture, because usually in a metallurgical plant, the quantity of NH3 used (to produce hydrogen) is vastly greater than the CO2 to be captured. In other words, this is a consequence of the steel plant using large amounts of NH3 as CCh-lean H2 carrier to significantly reduce CO2 emissions, and only using carbon capture for last mile hard-to-abate emissions. Additionally, the vaporliquid phase change enthalpy of ammonia is more than that of CO2. That is to say, in most embodiments of the present invention, not all the cold from the ammonia is to be used for CO2-capture and storage (as liquefied CO2). Remaining unused cold can be used to supply other cold consumers or in the case of absent demand, can be eliminated by sending cold first stream to an ammonia heating system.

[0060] In embodiments, the first stream is advantageously heated between steps c) and d) in an ammonia heating system. The ammonia heating system preheats cold ammonia to a hotter temperature suitable for being fed to the ammonia using device, where endothermic (preferably catalytic) reaction 2 NHs(g) — N2(g) + 3 H2(g)is happening. Temperature of the preheated stream of ammonia is higher than the temperature of the stream of ammonia upon exiting the ammonia storage installation, and is typically (well) above 10 °C, preferably above 50 °C or even above 100 °C. In embodiments, the temperature of the preheated stream of ammonia may be between about 300 °C and about 500 °C, such as about 350 °C, about 400 °C or about 450 °C.

[0061] Thermal energy may be supplied to the ammonia heating system as heat contained in the flue gas after flowing through the ammonia using device. Such a flue gas would already have delivered part of its heat for ammonia cracking (i.e. chemical transformation of ammonia), but the remaining heat would advantageously be used to pre-heat the stream of ammonia instead of being lost, thereby further reducing operation costs and need for resources of the metallurgical plant.

[0062] According to the same or other embodiments, the method may further comprise a step of transferring part of the extracted cold to a secondary cooling medium, e.g. a cooling medium used for equipment cooling (such as e.g. to water circulating through a blast furnace cooling stave, or to a cooling medium of a slag granulation system, or of the ammonia and / or CCh-storage installation) or air conditioning of on-site offices and accommodating spaces for operators of the metallurgical plant. Extracted cold may also be used in a powerplant (steam exiting a turbine must be cooled in a condenser to recover water in order to not excessively use up water), and / or for cooling in a metal forming process, such as in a casting or tempering process.

[0063] As mentioned above, in some embodiments, the ammonia using device chemically transforms at least part of the ammonia in a hydrogen-rich stream, i.e. performs ammonia cracking according to the following reaction: 2 NH3 — > N2 + 3 H2. This reaction being highly endothermic, it requires energy to occur, which is preferably provided to the ammonia using device as thermal energy by combustion of a fuel gas in a burning unit. Combustion of the fuel gas produces a (hot) flue gas having a temperature of at least about 500 or at least about 700 °C, preferably at least about 900 °C, more preferably at least about 1100 °C, even more preferably at least about 1300 °C.

[0064] In embodiments, the metallurgical plant further comprises an air separation system providing an 02-rich stream and a N2-rich stream. Preferably, theC -rich stream may be at least partially fed to the burning unit, to combust the fuel gas and produce the flue gas. A (further) portion of the O2-rich stream may further be fed to the metalmaking device (e.g. a blast furnace, a basic oxygen furnace, ... ).

[0065] Preferably, cold extracted from the first stream may be transferred to the air separation system and used therein to produce the O2-rich stream, e.g. via cryogenic distillation. O2 production typically requires a cooling water duty in the range of about 3 MJ / Nm3O2 produced, and O2 requirement for a method according to the present invention typically ranges between 30 000 and 60 000 Nm3 / h, corresponding to a requirement for thermal energy ranging between about 25 and about 55 MW.

[0066] Preferably the metal oxide reducing device of the metallurgical processing device is an ironmaking and / or steelmaking device, and more preferably comprises at least one of a shaft furnace, preferably a blast furnace, a fluidized and / or circulating bed reactor, a basic oxygen furnace, an electric arc furnace, a direct reduction reactor and / or a reduction melting furnace.

[0067] In some embodiments, the second stream is a CO2-rich stream produced by a basic oxygen furnace (BOF), i.e. the second stream is basic oxygen furnace gas, and CO2 is captured from the BOF gas by the present inventive method. Indeed, BOF gas comprises about 70 vol.-% CO, 20 vol.-% CO2 and the remainder being N2, H2O and others. After carbon capture, such a gas can ideally be used as a reducing gas in a blast furnace of the metallurgical plant (e.g. the metallurgical processing device). Decarbonated BOF gas can for example be added as cooling gas for shaft injection (possibly in addition to cracked ammonia, such as e.g. in addition to the third stream) or preferably added at the tuyere level, possibly together with natural gas, coke oven gas, and / or cracked ammonia. Decarbonated BOF gas (i.e. BOF gas having been submitted to a carbon capture process) may also be added to a syngas preparation unit containing an ammonia cracker (e.g. ammonia using device) and possibly also a reformer of any kind.

[0068] The ammonia storage installation storing ammonia, it preferably comprises an ammonia storage device (preferably a liquid ammonia storage device) and a refrigeration system configured for refrigerating the ammonia storage device. Indeed, albeit the storage device is insulated, thermal losses (namely cold losses) may occur. In other words, the refrigeration system is configured to (and used to)continuously cool (i.e. refrigerate) the ammonia storage device to compensate for cold losses through the storage insulation to the environment.

[0069] It shall be noted that nowadays, ammonia can be delivered to the metallurgical plant as either cold or uncooled ammonia. In the present text, uncooled ammonia refers to ammonia having a temperature higher than the temperature of ammonia stored in the ammonia storage installation, including ammonia with ambient temperature, and cold ammonia refers to ammonia having a temperature substantially identical to the temperature of ammonia stored in the ammonia storage installation.

[0070] While cold ammonia can be directly stored, uncooled ammonia needs to be cooled down. In embodiments, the refrigeration system of the ammonia storage installation is further configured for cooling uncooled ammonia arriving to the metallurgical plant to a temperature of the ammonia stored in the ammonia storage device. Accordingly, uncooled ammonia may be discharged into an intermediary buffer tank, before being gradually fed to the refrigeration system for conditioning to storage requirements (e.g. for cooling to temperature of the liquid ammonia stored into the ammonia storage device).

[0071] In preferred embodiments, wherein CO2 is liquefied in a CO2 capture plant by the cold extracted from the first stream (i.e. by the cold from the ammonia), the liquefied CO2 may be stored in a CO2-storage device and the refrigeration system of the ammonia storage installation may be synergistically exploited to not only compensate cold losses of the ammonia storage device but also of the CO2-storage device.

[0072] “About”, in the present context, means that a given numeric value covers a range of values from -20 % to +20 % of said numeric value, preferably a range of values from -10 % to +10 % of said numeric value, more preferably a range of values from -5 % to +5 % of said numeric value or even a range of values from -2.5 % to +2.5 % of said numeric value.Brief Description of the Drawings

[0073] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:Fig.1 is a schematic diagram of a method for operating a metallurgical plant according to a first embodiment of the present invention;Fig.2 is a schematic diagram of a metallurgical plant according to a second embodiment of the present invention; andFig.3 is a schematic diagram of a metallurgical plant according to a third embodiment of the present invention.Description of Preferred Embodiments

[0074] The schematic diagram of Fig.1 illustrates an embodiment of a first variant of the present method for operating a metallurgical plant 310.

[0075] Ammonia in the form of liquid ammonia at a temperature of e.g. -33 °C is delivered to the plant 310 as stream 201 from a cold ammonia delivery system 326 and stored in a storage tank, or ammonia storage device, of a liquid ammonia storage installation 312.

[0076] A first stream of liquid ammonia 204 is fed to a heat exchanger 314 (such as e.g. a vaporizer) where cold is extracted and transferred to a second stream 230, e.g. a stream 230 of a (comparatively) hot gas or a gas at ambient temperature. In the heat exchanger 314, heat is simultaneously extracted from the second stream 230 and transferred to the first stream, thereby inducing vaporization of the first stream into a stream of gaseous ammonia.

[0077] In other words, a first stream of liquid ammonia 204 and a second stream of fluid 230 enter the heat exchanger, and a stream of gaseous ammonia 205 and a stream 231 of fluid having a temperature lower than that of the second stream exit the heat exchanger.

[0078] The stream of gaseous ammonia 205 is then fed to an ammonia using device 316, or ammonia user, such as e.g. an ammonia cracker, where it is chemically transformed (preferably according to the following equation: 2 NH3(g) — N2(g) + 3 H2(g)) to produce a third stream of a hydrogen-rich gas 209. Energy required for the chemical transformation of gaseous ammonia into a H2-rich gas is at least partially provided by the heat exchange between the first and second streams, i.e. the elevation of temperature due to cold being extracted from the first stream advantageously reduces the energy requirement to initiate or sustain chemical transformation of the gaseous ammonia into the third stream.

[0079] The third stream 209, which normally has a high temperature of at least 500°C or higher, is then fed as reducing gas to a metal oxide reducing device, such as an ironmaking or a steelmaking device, 318. Prior to its feeding to the metal oxide reducing device, the third stream may be treated, e.g. to lower its N2 content, by means known in the art and not further described therein.

[0080] Example 1

[0081] Fig.2 discloses a second embodiment of a metallurgical plant 110 comprising iron and steelmaking devices 118 according to the present invention, and a method for operating such a plant. In the preferred embodiment of Fig. 2 (also referred to as embodiment 2), NH3 is used as a carrier for CCh-lean H2 and CO2-lean cryogenic cold to economically transport renewable CO2-lean energy and cold, produced from a renewable source, over long distances for the application in iron & steel making. The iron and steel making process is modified by injection of cracked ammonia to the blast furnace to reduce fossil coke consumption e.g. according to the method for operating a shaft furnace plant developed by Paul Wurth S.A. disclosed in WO 2023 / 052308 A1 . The injection in the blast furnace can principally be at every level, but preferably at shaft and / or tuyere level. The ammonia injected at tuyere level may furthermore be heated by help of electric energy, preferable by at least one plasma torch before being injected into the furnace (typically in the blow pipe of the injection system). As a minimum coke rate is required for process reasons in case of the blast furnace, it is evident that carbon capture is thus required if near-zero (or even net zero) CO2-lean steel shall be achieved. Near zero steel may be steel produced with CO2-emissions of less than 450 kg / tsteei. As an example, the present embodiment 2 considers a blast furnace with a 2,5 MTPA production rate of hot metal using plasma torches to heat reducing gas to achieve a low coke rate of about 160 to about 280 kgCoke / tHM (kg coke per metric ton hot metal), preferably about 160 to about 250 kgCoke / tHM, more preferably about 180 to about 230 kgCoke / tHM.

[0082] In this embodiment 2, the delivered ammonia is stored on site as refrigerated liquid, which is typical for large-scale ammonia storage. A typical storage capacity is equal to 15 days of consumption, i.e. about 1000 to about 3700 tons of ammonia consumed per day, corresponding to about 200 to about 600 Nm3NHs / tHM.

[0083] The storage installation 112 comprises or consists of an on-site NH3 storage (ammonia storage device) 112.1 , which is coupled with a storage refrigeration system 112.2. Already refrigerated cold delivery of NH3 (cold ammonia) 126 can be directly discharged as stream 1 into the on-site NH3 storage 112.1 , while hotter delivery of NH3 (uncooled ammonia) 128 is first discharged as stream 2 into an intermediary buffer tank 130 before it is fed gradually through stream 3 to the storage refrigeration system 112.2 for conditioning to storage requirements. Once conditioned, the ammonia is sent through stream 38 to the on-site NH3 storage. Besides conditioning to storage requirements of hot inbound delivery, the storage refrigeration system is also used to continuously cool the on-site NH3 storage to compensate for cold losses through the storage insulation to the environment. This is done by conditioning an incoming stream 37 and sending it back through stream 38.

[0084] The storage refrigeration system 112.2 can be synergistically exploited in embodiment 2 of the present invention to not only compensate cold losses of the on-site NH3 storage 112.1 , but also of a liquid CO2 storage device 144, storing CO2 captured in the steelmaking plant 110 and liquefied by the cold extracted from liquid ammonia as stream 4. A stream 35 can be taken from the liquid CO2 storage 144 to the storage refrigeration system 112.2 to be conditioned and sent back in stream 36 at a lower thermal energy content.

[0085] Alternatively or additionally, also a part of the stream 4 or a part of the stream 39 could be used to cool the CO2 storage tank (not shown). After taking up the energy from the CO2 storage tank 144 the stream can be integrated again, respectively in its later utilization (detailed below).

[0086] Next, the transported cold is recovered from stream 4 (first stream of liquid ammonia) and stream 6 to supply cooling capacity for CO2 cooling and an air separation plant 124. The potential cooling capacity for embodiment 2 ranges from about 30 MW to about 100 MW thermal cold assuming an ammonia temperature of -33 °C and an equilibrium reference temperature of 25 °C. The CO2 cooling requirement of the present embodiment would be around to 3 MW to 10 MW thermal cold to refrigerate and liquefy CO2 contained in compressed flue gas 30 at 20 bar. The availability of cold vastly outnumbers the requirement for CO2 capture, because usually just like in the present embodiment, the quantity of NH3 used (200.000 Nm3 / h) is vastly greater than the CO2 to be captured (40.000 Nm3 / h). This is a consequenceof the steel plant using large amounts of NH3 as CCh-lean H2 carrier to significantly reduce CO2 emissions, and only using carbon capture for last mile hard-to-abate emissions. Additionally, the vapor-liquid phase change enthalpy of ammonia (22.7 kJ / mol) is higher than that of CO2 (16.7 kJ / mol). The combination of these facts leads to the majority of embodiments of the present invention to have enough cold supply for carbon capture integration. The refrigeration and liquefaction of CO2, in case of embodiment 2, only requires about 10 MW cold out of the 70 MW cold available from the liquid NH3 to be vaporized. If the 10 MW of cold would have to be supplied by cooling water with an exemplar temperature difference of 10 K to 20 K between inlet and outlet, then this would result in 860 t / h and 430 t / h of cooling water flow rate respectively for typical bad and good cases. These numbers underline the benefit of generating the required cold at another location to reduce strain on local water and electricity resources. This also means that besides the roughly 10 MW of cold extracted from the NH3 between stream 4 and stream 5 in the CO2-cooler 114, there is still about 60 MW cold left.

[0087] In embodiment 2, this cold is beneficially used for cold requirement replacement in an air separation plant 124 fed with a stream of air 21 to produce N2 as stream 22 and O2 to be fed as stream 23 to a 02-storage device 146 and may then be used at least partially in stream 24 for oxy-burning in the burners 122 of the cracker 116 (i.e. ammonia using device) while another part (not shown) may be used for other applications (such as e.g. O2 injection in a blast furnace, or injection in a basic oxygen furnace), by supplying a part of the cold NH3 in stream 6 to the air separation plant 124, which returns a stream 7 higher in thermal enthalpy. In the present embodiment, cryogenic distillation for O2 production is assumed to prove the advantageous integration benefit of the present invention for CO2 capture. O2 production typically require cooling water duty in the range of about 3 MJ / Nm3O2 produced. The calculated O2 requirement for oxy-burning application in the burners 122 is about 45000 Nm3 / h, and thus equivalent to about 40 MW of cooling demand in the cryogenic distillation plant. By using the present invention in embodiment 2, a total of about 50 MW of cold duty can thus be supplied by the transported liquid ammonia, advantageously shifting the demand of 2000 t / h to 4000 t / h of cooling water from the local metallurgical plant site to the presumably renewable energy and water rich production site of ammonia,where CCh-lean energy and water can be sourced at a discounted price and with a lower impact to the environment, and CCh-lean H2 synthesis is attractive.

[0088] Remaining unused cold duty can be used to supply other cold consumers (e.g. as cold requirement for the cooling of steelmaking equipment such as a blast furnace, air conditioning system and / or water treatment plant and / or slag granulation plant) or in the case of absent demand, can be eliminated by sending cold NH3 in stream 39 to a NH3 heating system 120 together with the returning streams 7 and 5. Thus for a typical blast furnace producing 300 tons per hour (tph), and a slag granulation process with a slag rate of 300 kg / t HM and a production of 300 tph, this leads to a reduced cooling water requirement of 72 m3 / h or 50 MW cooling power.

[0089] The NH3 heating system 120 is supplied by thermal energy contained in a flue gas stream 17 and in case of need an additional energy stream 40. Stream 40 may be produced by oxy combustion to present a high CO2 content when being sent to the CO2-capture system. The NH3 heating system 120 preheats cold ammonia to a hotter temperature suitable for input stream 8 to the cracker 116 (i.e. ammonia using device), where endothermic catalytic reaction NHs(g) — 0,5 N2(g) + 1 ,5 H2(g) (and possibly further heating) is happening. The preheating temperature of the present embodiment is for example about 400 °C. The resulting hydrogen rich gas leaves the cracker as stream 9 and is sent to the ironmaking and steelmaking device(s) 118.

[0090] The cracker 116 is heated at a temperature level above 650 °C, preferably above 800 °C and more preferably above 900 °C, by combustion (oxycombustion, combustion with air or combustion with enriched air - comprising at least 30 vol.-%, preferably at least 40 vol.-%, more preferably at least 50 vol.-% of O2) of one part of stream 13 from the iron and steelmaking off gases stream 12 and / or by combustion from another fuel gas (not shown). Oxygen is supplied from the integrated air separation plant in stream 24. Produced flue gases from the burners 122 bring high temperature heat for the cracker in stream 16. Remaining lower temperature heat in stream 17 can be recovered in the NH3 heating system. Optionally, one part of stream 17 can be used to bypass the NH3 heating system to mix directly with the exiting stream 19 of the NH3 heating system. Optionally, to control flame temperature of the burners for cracker and reduce chemical energy requirement of stream 13, one part of stream 18 or 19 or a mixture thereof is recirculated back in stream 20 to the burners 122. In embodiments (not shown), the ammonia using device can also be composedof a cracker working at a certain temperature level, for example 650 °C followed by a heater which might further heat the hydrogen rich stream to a desired higher temperature level, for example 950 °C. In that case, the positioning of the burners at the heater and internal flue gas distribution between cracker and heater will be arranged in a way to optimize the heat efficiency of the process.

[0091] The remainder of the flue gas is sent to a flue gas cooler 132 in stream 25 to reduce temperature and optionally water vapor content, thereby producing a waste water stream 41. In embodiments, this step might also be configured for cleaning the gas from some impurities such as e.g. SOx, NOx, dioxins, ... by adding some additives to a scrubbing and cooling device. Cold and optionally dried (and / or cleaned) flue gas stream 26 is then cleaned of particle matter in a cyclone and / or filter system 134 to achieve a clean flue gas stream 27.

[0092] Flue gas stream 27 is subsequently dried below 100 ppm moisture level, preferable below 50 ppm and most preferred below 20 ppm in stream 28 by a drying system 136 to avoid downstream frost in the cryogenic system. A waste water stream 34 is thus produced at the drying system.

[0093] Dried flue gas stream 28 is compressed with a flue gas compressor 138 to pressures above the storage pressure in stream 32, ensuring a certain depressurization possibility within the cryogenic liquefaction system to benefit from the Joule-Thomson effect to lower the temperature enough to liquefy CO2. After compressing stream 28, the hotter stream 29 is optionally cooled with a pre-cooler 140 to reduce cooling load of the NH3 based CO2 cooler 114 in case additional NH3 cooling duty is needed elsewhere. But in the present embodiment, the pre-cooler 140 is not necessary due to the large excess of NH3 cooling capacity available, making stream 30 the same as stream 29.

[0094] Stream 29 is cooled with the integrated NH3 based CO2 cooler 114, using about 10 MW of cooling duty in case of the present embodiment. The colder stream 31 can thus reach temperatures of about -20 °C and liquefaction of CO2 can be achieved within the CO2 cooler, with a flue gas pressure of about 20 ba in stream 30. This way maximal cold can be extracted from the NH3 in the CO2 cooler, as the majority of the cold is used for phase change of the CO2 (16,7kJ / mol) rather thansensible cold due to temperature change, which is less than 2 kJ / mol to cool down gaseous CO2 from 25 °C to -20 °C.

[0095] After using the CCh-lean cold from NH3, the conditioned flue gas stream31 is sent to the cryogenic liquefaction device 142, for producing a liquid CO2 stream32 and a cold cryogenic tail gas stream 33. Liquid CO2 stream 32 shall be acceptable for storage in the storage device 144 with temperature and pressure levels required. The cryogenic tail gas 33, containing low amounts of CO2, preferably below 50 vol.- %, more preferably below 20 vol.-%, or even more preferably below 10 vol.-%, can be either discharged into atmosphere after ensuring compliance to emission standards, or further integrated for cold recovery such as in the drying system. In the embodiment of figure 2, the stream 33 is calculated to have a temperature of below 0 °C, making it fully suitable for providing drying cold to achieve flue gas moisture levels targeted in stream 28.

[0096] Example 2

[0097] Fig.3 discloses a third embodiment of a metallurgical plant 410 comprising a metallurgical processing device with a plant unit 418 according to the present invention, and a method for operating such a plant. In the preferred embodiment of Fig.3 (also referred to as embodiment 3), NH3 is used as energy supply source.

[0098] A first stream of liquid ammonia 404 is fed to a heat exchanger 414 (such as e.g. a vaporizer) where cold is extracted and transferred to a second stream 430, e.g. a stream 430 of a (comparatively) hot gas or a gas at ambient temperature. In the heat exchanger 414, heat is simultaneously extracted from the second stream 430 and transferred to the first stream 404, thereby inducing vaporization of the first stream into a stream of gaseous ammonia 405.

[0099] In other words, a first stream of liquid ammonia 404 and a second stream of fluid 430 enter the heat exchanger, and a stream of gaseous ammonia 405 and a stream 431 of fluid having a temperature lower than that of the second stream exit the heat exchanger.

[0100] The stream of gaseous ammonia 405 is then at least partially fed to a burner 448 where it is combusted to produce a third stream 409 being a stream of a hot flue gas.

[0101] In embodiments, another part of the stream of gaseous ammonia 405 is also fed to an ammonia cracker 416, where it is chemically transformed (preferably according to the following equation: 2 NHs® — N2(g) + 3 H2(g)) to produce a stream of cracked ammonia 450. Energy required for the chemical transformation of gaseous ammonia into cracked ammonia is at least partially provided by the heat exchange between the first and second streams, i.e. the elevation of temperature due to cold being extracted from the first stream advantageously reduces the energy requirement to initiate or sustain chemical transformation of the gaseous ammonia into the third stream. The stream of cracked ammonia 450 may then be fed to the burner 448 along with the stream 405 of gaseous ammonia and possibly also any other fuel 451 suitable for producing a hot flue gas 409.

[0102] The third stream 409 is then fed as heat (and thus energy) carrier to a plant unit 418 of the metallurgical plant 410, such as e.g. a reheating furnace or any other device with heat / heating requirements.

Claims

Claims1 . A method for operating a metallurgical plant comprising an ammonia storage installation, an ammonia using device, and a metallurgical processing device, the method comprising the steps of a) conveying a first stream of ammonia from the ammonia storage installation toward the ammonia using device, b) collecting a second stream of fluid, preferably from an installation of the metallurgical plant, c) extracting cold from the first stream and transferring extracted cold at least in part to the second stream to cool the second stream and / or extracting heat from the second stream and transferring extracted heat at least in part to the first stream, preferably to heat and / or gasify the first stream, characterized in that the method further comprises the steps of d) chemically and / or thermally transforming ammonia from the first stream in the ammonia using device to produce a third stream, and e) feeding the third stream to the metallurgical processing device.

2. The method as claimed in claim 1 , wherein the metallurgical processing device comprises a metal oxide reducing device, wherein the ammonia using device comprises an ammonia cracker, the third stream produced in step d) being a stream of hydrogen-rich gas, and wherein the third stream is fed to the metal oxide reducing device.

3. The method as claimed in any one of the preceding claims, wherein the metallurgical processing device comprises a plant unit, preferably a reheating furnace, an annealing furnace, a sinter plant and / or a pellet plant; wherein the ammonia using device comprises a burner to combust the first stream, the third stream produced in step d) being a hot stream heating the plant unit.

4. The method as claimed in claim 3, wherein the burner combusts the first stream alone or a mixture of the first stream and a fuel and / or cracked ammonia.

5. The method as claimed in any one of the preceding claims, wherein the ammonia storage installation comprises a liquid ammonia storage tank and / or wherein the first stream is a stream of liquid ammonia.

6. The method as claimed in any one of the preceding claims, wherein the second stream has a temperature higher than the first stream, preferably of at least10 °C, more preferably at least 20 °C, even more preferably at least 40 °C, and heat is extracted as sensible heat and / or wherein the second stream of fluid is a stream of gas and heat is extracted as condensation heat of a gas-to-liquid phase transition of the second stream.

7. The method as claimed in any one of the preceding claims, wherein the second stream is a CCh-rich stream and wherein CO2 is purified, preferably by liquefaction, from the second stream by the cold extracted from the first stream, in a CO2-capture plant or in a CO2-separation plant.

8. The method as claimed in claim 7, wherein at least a part of the CO2-rich stream is generated by a component of the metallurgical plant, preferably by at least one of the ammonia using device, the metallurgical processing device, and an ammonia heating system.

9. The method as claimed in any one of the preceding claims, wherein heat and / or cold is extracted by direct heat exchange between the first and second streams in a heat exchanger and / or in an evaporative cooler.

10. The method as claimed in any one of the preceding claims, wherein cold from the first stream is directly transferred to the second stream in an ammonia- based refrigeration system.

11. The method as claimed in any one of the preceding claims, wherein cold extracted from the first stream is further transferred to a secondary cooling medium.

12. The method as claimed in any one of the preceding claims, wherein energy is provided to the ammonia using device as thermal energy by combustion of a fuel gas in a burning unit.

13. The method as claimed in claim 12 in which the burning unit bums a process gas produced within the metallurgical plant.

14. The method as claimed in any one of the preceding claims, wherein the metallurgical plant further comprises an air separation system providing a O2- rich stream and a N2-rich stream.

15. The method as claimed in claim 14 when depending on claim 12 or 13, wherein the 02-rich stream is at least partially fed to the burning unit.

16. The method as claimed in claim 14 or 15 when depending on claim 2, wherein the 02-rich stream is partially fed to the metal oxide reducing device.

17. The method as claimed in any one of claims 14 to 16, wherein cold extracted from the first stream is used to produce the Ch-rich stream in the air separation system.

18. The method as claimed in any one of the preceding claims, wherein cold extracted from the first stream is used for cooling requirements of the metallurgical plant, preferably for equipment cooling and / or air conditioning.

19. The method as claimed in any one of the preceding claims, wherein the first stream is further heated between steps c) and d) in an ammonia heating system.

20. The method as claimed in any one of the preceding claims, wherein the metal oxide reducing device is an ironmaking and / or steelmaking device, preferably comprising a blast furnace, a fluidized bed reactor, a basic oxygen furnace and / or an electric arc furnace.

21. The method as claimed in any one of the preceding claims, wherein the ammonia storage installation comprises an ammonia storage device and a refrigeration system configured for refrigerating the ammonia storage device and preferably further configured for cooling ammonia arriving to the metallurgical plant to a temperature of the ammonia stored in the ammonia storage device.

22. The method as claimed in claim 21 when depending on claim 7, wherein the CO2-capture plant or the CCh-separation plant further comprises a CCh-storage device and wherein the refrigeration system of the ammonia storage installation is further configured for refrigerating the CC -storage device23. A metallurgical plant comprising an ammonia storage installation, an ammonia using device and a metallurgical processing device, wherein: the ammonia using device is in fluidic downstream communication with the ammonia storage installation and in fluidic upstream communication with the metallurgical processing device; the ammonia using device is configured for chemically transforming ammonia of a first stream from the ammonia storage installation to produce a third stream; the plant further comprising means configured to extract cold from the first stream and transfer it at least in part to a second stream of fluid,wherein the means configured to extract cold are arranged between the ammonia storage installation and the ammonia using device in fluidic communication therewith.

24. The metallurgical plant as claimed in claim 23, wherein the plant further comprises a CCh-generating device and the second stream is a CCh-rich gas generated by the CCh-generating device.

25. The metallurgical plant as claimed in claim 23 or 24, further comprising a CO2- capture plant or a CCh-separation plant, preferably comprising a CCh-storage device.

26. The metallurgical plant as claimed in any one of claims 23 to 25, further comprising a burning unit configured for producing a flue gas fed to the ammonia using device.

27. The metallurgical plant as claimed in any one of claims 23 to 26, further comprising an air separation system arranged in fluidic communication with the burning unit and the means for extracting cold.

28. The metallurgical plant as claimed in claim 27, further comprising an ammonia heating system arranged between the means configured for extracting cold and the ammonia using device, and in fluidic communication therewith.

29. The metallurgical plant as claimed in any one of claims 23 to 28, wherein the ammonia storage installation comprises a liquid ammonia storage tank and / or wherein the stream of ammonia is a stream of liquid ammonia.

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