Blast furnace plant and method for operating the same

Abstract

A method for operating a blast furnace is proposed, the method comprising the following steps: collecting blast furnace gas flow from the blast furnace; feeding the blast furnace gas flow and hydrocarbon-containing gas to a reforming facility including at least one reformer; reforming the blast furnace gas flow and the hydrocarbon-containing gas in the reforming facility to generate a synthesis gas flow; and feeding at least a portion of the synthesis gas flow to the blast furnace; wherein an H2 stream is added to the hydrocarbon-containing gas before step (c), and / or to the blast furnace gas flow before step (c), and / or to the synthesis gas flow before step (d), and / or to the tuyeres of the blast furnace; wherein feeding at least a portion of the synthesis gas flow to the blast furnace occurs through the blast furnace shaft and / or through the blast furnace tuyeres; and wherein, in a blast furnace facility including a blast furnace, a reforming facility, and a Cowper furnace, the hydrogen utilization efficiency is greater than 60%.

Description

Technical Field

[0001] The present invention generally relates to methods for operating blast furnace equipment and such blast furnace equipment. Prior Technology

[0002] Despite the existence of alternative methods, such as scrap melting or direct reduction in an electric arc furnace, the blast furnace still represents the most widely used equipment for steel production today. One of the problems with blast furnaces is the blast furnace gas (BFG), often referred to as "top gas," emitted from the top of the furnace. While it may have been permissible in the past to simply release this top gas into the atmosphere, this has since been avoided by using BFGs in power generation facilities that feed them, so as not to waste the energy contained in the gas and to avoid undue burden on the environment. One component of blast furnace gas is CO2, which is harmful to the environment and essentially useless for industrial applications. In fact, exhaust gases from power generation facilities that feed blast furnace gas typically contain CO2 at concentrations as high as 20 vol% to 40 vol%. In addition to the aforementioned CO2, combusted blast furnace gas typically also contains considerable amounts of N2, CO, H2O, and H2. However, the N2 content depends heavily on whether the blast furnace uses hot air or (pure) oxygen.

[0003] Primarily aimed at reducing the amount of coke or other carbon sources used, the following suggestion has been made: recover blast furnace gas, treat it to increase its reduction potential, and inject it back into the blast furnace to aid the reduction process. One method for carrying out such a process is to reduce the CO2 content in the blast furnace gas using Pressure Swing Adsorption (PSA) or Vacuum Pressure Swing Adsorption (VPSA), as disclosed in European Patent Application EP 2 886 666 A1. Although PSA / VPSA equipment allows for a significant reduction in CO2 content in blast furnace gas from approximately 40% to approximately 5%, the acquisition, maintenance, and operation of such equipment are very expensive, and it also requires a large amount of space.

[0004] It has also been proposed to use blast furnace gas as a hydrocarbon reforming agent to obtain synthesis gas (also known as syngas) suitable for various industrial purposes. According to the proposed reforming process, blast furnace gas is mixed with a carbonaceous gas mixture containing at least one hydrocarbon (e.g., a low-carbon alkane). In the so-called dry reforming reaction, the hydrocarbon gas reacts with CO2 in the blast furnace gas to produce H2 and CO. Simultaneously, through the so-called steam reforming reaction, the hydrocarbon reacts with H2O in the blast furnace gas to also produce H2 and CO.

[0005] In the context of reducing CO2 emissions, considerable efforts have also been made to reduce the use of carbonaceous fuels for blast furnace operation itself. As an alternative, fuels with increased hydrogen content are used, in the form of hydrocarbons, gaseous hydrogen (H2), or mixtures thereof. Hydrogen and hydrocarbons have high calorific value and the potential to be injected into the blast furnace tuyeres as auxiliary fuels. The higher the hydrogen content in the belly and flank gas, the higher the CO2 reduction potential typically used for blast furnace operation. "Bottom gas" generally corresponds to the gas in the blast furnace's melting zone, while in the context of this paper, "flank gas" refers to the gas injected into the blast furnace flank (i.e., above the melting zone).

[0006] However, the injection of cold H2 and / or hydrocarbons, along with a large amount of pulverized coal (PCI), at the tuyere level significantly reduces the RAFT (raceway adiabatic flame temperature). To increase RAFT, a higher oxygen enrichment is required, which is limited by the temperature of the gas at the furnace top. Therefore, only a relatively small amount of cold H2 and / or hydrocarbons can be injected into the blast furnace through the tuyere, limiting the CO2 saving potential of this technology.

[0007] Injecting hot hydrogen or even hot hydrocarbons (such as natural gas) at or through the tuyeres allows for higher hydrogen utilization and greater CO2 savings from the blast furnace. However, the production of hot hydrogen, and especially hot hydrocarbons, is technically not straightforward because hydrocarbons tend to crack at higher temperatures, and steel tends to decarburize when exposed to hot hydrogen, making the steel prone to cracking.

[0008] Furthermore, when hydrocarbons and / or hydrogen are injected into the blast furnace, only a portion of the hydrogen is used to reduce iron ore within the blast furnace, while the remainder leaves the blast furnace with the top gas, further limiting the benefits of hydrogen and / or hydrocarbon injection. The percentage of hydrogen consumed in the blast furnace worsens when hydrocarbon and / or hydrogen injection leads to an increase in the amount of hydrogen in the blast furnace. This means that the potential for CO2 emission reduction is reduced for a given amount of hydrogen when the amount of hydrogen used in the blast furnace increases.

[0009] Finally, this is particularly problematic when the hydrogen injected into the blast furnace is renewable hydrogen produced by electrolysis. In fact, using a portion of the blast furnace gas leaving the blast furnace facility in a cogeneration facility typically results in a low thermal efficiency of approximately 25% to 35%. This means that when this portion of the blast furnace gas is used for electricity production, 65% to 75% of its energy is lost. Therefore, especially in blast furnace facilities utilizing expensive, low-carbon energy sources such as hydrogen, the use of blast furnace gas for electricity production should be avoided whenever possible. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a new method for operating a blast furnace and a corresponding blast furnace facility, thereby allowing for efficient hydrogen utilization in the blast furnace facility, reducing CO2 emissions caused by conventional blast furnace steelmaking, and at least partially overcoming the aforementioned problems.

[0011] This objective is achieved by the methods according to Request 1 and Request 2, and by the blast furnace equipment according to Request 19.

[0012] To achieve the aforementioned objective, the present invention provides, in a first aspect, a method for operating a blast furnace, comprising the following steps: (a) Collecting blast furnace gas flow from a blast furnace having a furnace body and at least one tuyere; (b) Feeding blast furnace gas stream and hydrocarbon-containing gas to a remodeling facility that includes at least one remodeler; (c) Recombining blast furnace gas stream and hydrocarbon-containing gas in a recombining facility to produce a synthesis gas stream; and (d) At least a portion of the synthesis gas flow is fed into the blast furnace.

[0013] H2 is added to the hydrocarbon-containing gas stream before step (c), and / or to the blast furnace gas stream before step (c), and / or to a mixture comprising blast furnace gas and hydrocarbon-containing gas before step (c), and / or to the synthesis gas stream before step (d). H2 addition is performed to increase the amount of H2 injected (i.e. fed) into the blast furnace. The method according to the invention does not include any H2 removal steps. Feeding at least a portion of the synthesis gas stream into the blast furnace occurs at the shaft level / through the blast furnace shaft. Alternatively, feeding at least a portion of the synthesis gas stream into the blast furnace occurs at the tuyeres level / through the blast furnace tuyeres or both through the blast furnace shaft and through the blast furnace tuyeres. In other words, in some embodiments, a portion of the synthesis gas stream is fed at the shaft level, and another portion of the synthesis gas stream is simultaneously fed through the blast furnace tuyeres; while in other embodiments, the feeding of the synthesis gas stream occurs only through the blast furnace shaft.

[0014] In this embodiment, an additional stream of hydrogen and / or hydrocarbons may be added at the tuyeres of the blast furnace.

[0015] Although this method can be applied to the production of other metals, such as lead or copper, blast furnaces are typically used to produce pig iron.

[0016] In the context of this invention, syngas refers to the syngas produced in a recombination process in a recombination unit.

[0017] In the context of this invention, a recombining facility includes at least one recombiner. In embodiments, the recombining facility may include multiple recombiners arranged in series or parallel with each other; or the recombining facility may include multiple recombiners arranged to form at least two recombiner series arranged in parallel with each other. The recombiners in the recombining facility can be of any type, such as any type of regenerative recombiner or catalytic dry and / or wet recombiner, particularly bottom-burning, side-burning, platform-type, or top-burning recombiners. In embodiments where the recombining facility includes more than one recombiner, the recombiners may be the same or different from each other. For example, the recombining facility may include a pre-recombiner and a main recombiner. The exact number, type, and arrangement of the recombiners in the recombining facility may be advantageously adjusted according to the level at which the generated syngas is subsequently fed to the blast furnace to meet requirements for the generated syngas (e.g., temperature, reduction degree), or according to the location of hydrogen addition.

[0018] For the reorganization process to take place in the reorganization facility, carbon dioxide and steam sources, such as collected blast furnace gas, and hydrocarbon-containing gases must be combined (i.e. mixed) to form a gas mixture before or upon entering the reaction chamber of the first reorganizer in the reorganization facility. In embodiments where the reorganization facility includes only one reorganizer, the first reorganizer corresponds to that reorganizer.

[0019] The gas recombined in the reactor is a mixture of blast furnace gas and hydrocarbon-containing gases and, possibly, steam, and is more or less well mixed. Combining blast furnace gas with hydrocarbon-containing gases and, possibly, steam generally means "allowing blast furnace gas to mix with hydrocarbon gases and, possibly, steam." This can include (actively) mixing blast furnace gas with hydrocarbon-containing gases and, possibly, steam, i.e., applying mechanical force to mix the gases. However, in some cases, such as injecting the gas into a pipe, it may be sufficient to allow mixing to occur more or less passively through convection and / or diffusion. However, it should be understood that a higher degree of mixing promotes chemical reactions. It is possible to combine and mix the gases in a dedicated container, which may be called a mixing container or mixing chamber. In embodiments, it may also be sufficient to inject blast furnace gas and hydrocarbon-containing gases and, possibly, steam separately into the reformer and allow the gases to mix within the reformer (e.g., in the pre-chamber of the reformer).

[0020] On the one hand, the present invention also proposes a method for operating a blast furnace by improving the efficiency of hydrogen utilization. The method includes adding H₂ to the combination of the blast furnace and the reorganization reaction; wherein the hydrogen utilization portion in the blast furnace facility, which includes the blast furnace, reorganization facility, and Cowper plant, is higher than 60% of the hydrogen fed to the blast furnace, and preferably higher than 65%; wherein the total hydrogen fed to the blast furnace is a flow of at least 200 Nm³ per ton of molten iron produced, and wherein at least 50 Nm³ per ton of molten iron is fed to the blast furnace facility in the form of molecular hydrogen H₂.

[0021] Hydrogen utilization is defined as: (hydrogen input to the blast furnace facility – hydrogen output from the blast furnace facility) / (hydrogen input to the blast furnace facility).

[0022] Hydrogen input to the blast furnace, or hydrogen fed into the blast furnace, or hydrogen introduced into the blast furnace facility, is defined as the total hydrogen content of the belly gas (i.e., the gas in the softening zone of the blast furnace) and the blast furnace gas injected into the blast furnace at the blast furnace level. This hydrogen input to the blast furnace specifically includes the hydrogen contained in the syngas, the injected molecular hydrogen (H₂), other hydrogen-containing gases, the injected coal and / or tar, the injected gaseous and solid fuel moisture, and the moisture contained in the hot blast.

[0023] Hydrogen export is defined as the amount of hydrogen contained in the blast furnace gas leaving the blast furnace at the top of the blast furnace, minus its utilization in the Cowper furnace facility and, if applicable, in the reprocessing facility.

[0024] On the other hand, the present invention proposes a blast furnace facility, comprising a blast furnace having a furnace body, tuyeres arranged for supplying hydrogen-containing gas to the blast furnace, and gas inlets arranged within the furnace body for supplying a synthesis gas stream (preferably a thermal synthesis gas stream) to the blast furnace. The blast furnace facility further includes: A reforming facility including at least one reformer connected to the top of a blast furnace and to a source fluid containing hydrocarbon gas, the reforming facility being arranged to convert the blast furnace gas stream and hydrocarbon gas into a synthesis gas stream, and the reforming facility being downstream connected to the gas inlet fluid in the blast furnace body; and A source of H2 flow that is fluidly connected to at least one reconstituter and / or to a gas inlet in the blast furnace and / or to the tuyeres of the blast furnace. In one embodiment, the reorganization facility may also be connected downstream of the blast furnace tuyeres.

[0025] Advantageously, the blast furnace equipment is configured to operate by implementing the method according to the first aspect and described in more detail below.

[0026] Therefore, this disclosure proposes an integrated method and corresponding equipment that allows blast furnaces to be operated with a reduced ratio of coke to other carbon sources, a smaller CO2 footprint, and improved hydrogen (H2) utilization efficiency.

[0027] In fact, the inventors have discovered that by combining hydrogen (H2) utilization, blast furnace gas recycling, and hydrocarbon recombination, CO2 emissions from blast furnace equipment can be reduced without negatively impacting the quality of the produced metals (e.g., pig iron). Therefore, one of the main advantages of this method and equipment is that by reprocessing a portion of the blast furnace gas for reuse, the total CO2 production of blast furnace operations can be significantly reduced.

[0028] Another major advantage is that by reprocessing a portion of the blast furnace gas for reuse, the overall energy efficiency of the blast furnace facility, including the blast furnace, reprocessing facility, and Cowper furnace, can be improved, thereby increasing hydrogen utilization efficiency. Added H₂ is typically not entirely consumed within the blast furnace facility; therefore, at least a portion of the added H₂ leaves the blast furnace facility in the outlet blast furnace gas. In the context of this paper, outlet blast furnace gas refers to the blast furnace gas leaving the blast furnace after its consumption within the blast furnace facility; more specifically, it is the blast furnace gas remaining after its consumption in the blast furnace, Cowper furnace, and reprocessing facility. Utilizing the blast furnace gas in the reprocessing facility as fuel gas for burners in at least one reprocessor also improves the utilization of blast furnace gas within the blast furnace facility. Blast furnace gas collected and recycled within the blast furnace facility for syngas production will be used with very high overall energy efficiency. Through reprocessing, it can be used directly and indirectly for metallurgical purposes in the blast furnace, rather than being sent to, for example, thermal power generation facilities. Therefore, at least a portion of the emitted H₂ will not burn and will generate energy, such as electricity, with low energy efficiency. In other words, less energy is wasted due to the combustion of H₂, and the overall energy efficiency of H₂ utilization is improved.

[0029] In fact, hydrogen production often requires a large amount of energy and is carried out at a production efficiency of about 60%. When hydrogen is injected into a blast furnace, only a portion of it is used to reduce the iron ore inside. Typically, 30% to 55% of the added hydrogen is used for the reduction of the iron ore, with the remainder leaving the blast furnace in the top gas. Combustion of the hydrogen contained in the blast furnace top gas will generate electricity at a production efficiency of about 30%. This results in a "loss" of 59% to 69% of the electrical energy used to produce this portion of hydrogen.

[0030] Hydrogen is collected at the top of the blast furnace and reused in the blast furnace facility using highly efficient (typically above 80%) recombining technology, which reduces the proportion of hydrogen used in power generation facilities and thus reduces the proportion of energy loss.

[0031] Furthermore, injecting the resulting syngas at the blast furnace level allows for a significant reduction in coke yield, i.e., the amount of pig iron coke and / or other carbon sources produced per ton.

[0032] Additionally, injecting syngas into the blast furnace allows for the injection of pulverized coal, natural gas, and especially hydrogen or other materials into the higher tuyeres. Therefore, hydrogen-rich auxiliary fuels can replace additional coke, allowing for further reductions in the carbon content of the blast furnace reducing agent and thus reducing CO2 emissions.

[0033] Nevertheless, a higher auxiliary injection rate leads to even lower hydrogen utilization and requires even more blast furnace gas recycling. As also shown in the alternative embodiments, this problem can be solved by this method.

[0034] The temperature of the syngas injected through the furnace body should be approximately 950°C but not exceeding 1050°C to prevent melting of the materials inside the furnace.

[0035] In embodiments where the syngas flow to be fed through the furnace is produced by a reforming facility including at least one reformer with a high temperature level (i.e., typically higher than the temperature level used for furnace injection), it is advantageous to add H2 to the hot syngas flow downstream of at least one reformer. The H2 flow thus acts as a coolant for the syngas flow. Using hydrogen in this way (i.e., as a coolant) completely eliminates the need to heat the hydrogen in expensive heating units before it is injected through the blast furnace. In effect, the excess heat of the syngas will be advantageously used to heat the hydrogen. This allows for increased process efficiency by eliminating the need for both cooling the syngas and heating the hydrogen.

[0036] Additionally, using hydrogen in this configuration allows for a higher feasible hydrogen injection rate in the blast furnace because the hydrogen is heated in the reformer and injected at the furnace level as part of the syngas. In other words, a single hot gas injection system is required to perform the injection of both syngas and hydrogen, without the need for a separate system to heat the hydrogen to the injection temperature at the furnace level.

[0037] Furthermore, while the pressure levels of reformers are relatively high in other industries, mostly above 20 barg or even above 40 barg, the required pressure levels in blast furnace applications are only 1.5 barg to 6 barg. This has a significant impact on the operating conditions and limitations of reforming equipment, such as carbon formation and equilibrium conversion. Although lower pressure levels will favor higher methane conversion at the same temperature level, unfortunately, this also favors soot formation. For this reason, adding H2 stream to the blast furnace gas stream and / or to hydrocarbon-containing gases upstream of the reformer is particularly advantageous, as this partially inhibits soot formation, even though it simultaneously reduces methane conversion at a given temperature compared to not adding hydrogen.

[0038] Hydrogen can also be added both upstream of the reformer to the hydrocarbon-containing gas and / or blast furnace gas stream, and also to the syngas stream to be injected at the furnace level. The addition of hydrogen needs to be balanced between its utilization as a coolant in the syngas stream to be fed through the furnace and its addition upstream of the reformer to the hydrocarbon-containing gas and / or blast furnace gas stream for syngas production. As already mentioned, adding hydrogen to the hydrocarbon-containing gas and / or blast furnace gas stream will help reduce soot formation during the reforming reaction.

[0039] Another advantage of the method of the present invention for operating a blast furnace is that hydrogen is injected either as cold hydrogen (i.e., an unheated stream heated only to an economically meaningful temperature level) or as pure hot H2 (i.e., without CO2 and / or H2O content) to prevent steel from cracking.

[0040] The main advantages and benefits of the operating method and blast furnace equipment disclosed herein can be summarized as follows: l Reduce soot formation during the reorganization process l Reduce coke yield Increased auxiliary fuel injection levels at the vent, and especially increased levels of hydrogen-containing fuels (such as hydrocarbons and / or pure hydrogen). Due to the significant CO2 savings resulting from replacing fossil fuels with hydrogen. The low viscosity of H2 improves blast furnace operation, preventing problems such as material collapse in the furnace body and improving the hydrodynamics of the remelting zone in the coke bed with counter-current liquid phase (molten iron and slag descending) / gas phase (gas ascending). The circulation of gas from the top of the blast furnace increases hydrogen utilization in the blast furnace facilities, resulting in higher hydrogen utilization energy efficiency.

[0041] These and other advantages of the method for operating the blast furnace and the blast furnace equipment of this disclosure will be further described below.

[0042] In the embodiments, the disclosed method for operating a blast furnace further includes the following sub-steps: a1) Optionally, the hydrocarbon-containing gas and / or blast furnace gas may be hydrogenated and / or desulfurized; c1) A portion of the blast furnace gas is fed separately or in a mixture with other gases to the burner of the reformer.

[0043] In such embodiments, gas cleaning, reforming conditions, and syngas temperature requirements can be advantageously adjusted depending on the location of hydrogen addition. Advantageously, H2 can be added to the blast furnace gas stream and / or hydrocarbon-containing gas upstream of the hydrogenation unit (before step a1), upstream of the reformer (before step b), and / or downstream of the reforming facility (after step c), if the syngas temperature is too high for its direct injection into the blast furnace.

[0044] Optionally, the steam stream may be added to the hydrocarbon-containing gas before steps a1) and c), and / or added to the blast furnace gas stream before step c), or added to the mixture of blast furnace gas and hydrocarbon-containing gas before step c).

[0045] The H2 stream and / or hydrocarbon-containing gas stream and / or blast furnace gas stream can be heated, particularly any or all of these streams can be heated before the recombining process, preferably in a heat exchanger that preferably recovers some of the energy from the flue gas from the recombiner. Preferably, the hydrocarbon-containing gas stream and / or blast furnace gas stream are preheated (i.e., heated to a moderate temperature) upstream of the recombiner. In embodiments where the H2 stream is added to the hydrocarbon-containing gas stream and / or blast furnace gas stream, the H2 stream can be preheated in a dedicated heating device before being added to the hydrocarbon-containing gas stream and / or blast furnace gas stream. Alternatively, the H2 stream and the hydrocarbon-containing gas stream and / or blast furnace gas stream can be preheated simultaneously after addition. However, in embodiments where the H2 stream is added to the synthesis gas stream downstream of the recombiner, it is preferable not to heat the H2 stream or only to an economically meaningful temperature level, i.e., a temperature level that does not require expensive preventative measures against high-temperature hydrogen attack, typically below 600°C or even below 400°C. In the context of this disclosure, an unheated hydrogen stream or a hydrogen stream heated only to an economically meaningful temperature level is referred to as cold.

[0046] In the embodiments, depending on the composition of the hydrocarbon-containing gas, desulfurization of the hydrocarbon-containing gas may be required. For example, sulfur removal in a zinc oxide bed requires sulfur to be present in an inorganic form, more specifically as H₂S. However, hydrocarbon-containing gases very commonly also include organic sulfur, which needs to be converted into inorganic sulfur H₂S in the presence of hydrogen and a specific catalyst. Therefore, in the embodiments, it is advantageous to add hydrogen to the hydrocarbon gas before the hydrogenation step (step a1) if desulfurization is required. For blast furnace gas, this hydrogen addition is not necessarily required, as the blast furnace gas itself may contain sufficient hydrogen for the hydrogenation process.

[0047] Advantageously, a portion of the energy from the flue gas of the reforming process is also used in the heat exchanger to heat the fuel gas, which includes a portion of the blast furnace gas and the air used accordingly in the burner of at least one reformer in the reforming facility.

[0048] In a preferred embodiment, the H2 stream is generated by electrolysis in an electrolysis cell. Preferably, the hydrogen is renewable or "green". In the context of this disclosure, renewable or "green" hydrogen means that it is preferably generated by the electrolysis of water and / or steam, and / or the electricity used to operate the electrolysis cell is generated from renewable resources such as wind, solar and / or hydropower.

[0049] In the context of this disclosure, the term "hydrocarbon" or "hydrocarbon-containing gas" refers to any hydrocarbon that is in a gaseous state at ambient temperature. Therefore, such hydrocarbon gases include natural gas, i.e., a mixture of fossil-derived, naturally occurring hydrocarbon gases that is primarily composed of methane and typically includes varying amounts of other higher alkanes, but also include gases with similar hydrocarbon components, such as biogas and coke oven gas. Coke oven gas is a mixture of several gases, primarily hydrogen (i.e., having a hydrogen content of at least 50%), methane (typically comprising 25% of coke oven gas), and the remainder being a mixture of various gases such as nitrogen, CO, CO₂, or H₂O. Therefore, coke oven gas itself already contains a significant amount of hydrogen.

[0050] Preferably, the hydrocarbon-containing gas includes natural gas, coke oven gas, and / or biogas.

[0051] Restructuring reactors can be of any type, such as catalytic restructuring reactors, regenerator-type reactors also known as regenerative restructuring reactors, restructuring reactors with plasma torches, partial oxidation restructuring reactors, and restructuring reactors with oxygen / carbon and / or hydrocarbon burners.

[0052] Advantageously, the syngas gas produces either a dry or wet reforming process. In the so-called dry reforming process, hydrocarbons (such as methane) react with CO2 in the blast furnace gas to produce H2 and CO. Therefore, the dry reforming reaction is CH4 + CO2 = 2CO + 2H2. In the so-called wet reforming process, hydrocarbons also react with H2O in the blast furnace gas to produce H2 and CO. Therefore, the wet reforming reaction is CH4 + H2O = CO + 3H2. In either case, syngas with significantly increased H2 and CO concentrations is obtained.

[0053] The reforming process can be carried out catalytically or non-catalytically. In particular, the reforming process of natural gas can be carried out catalytically or non-catalytically, while the reforming of coke oven gas is preferably carried out non-catalytically. Catalytically carried out processes occur in the presence of a catalyst; while non-catalytically carried out processes occur in the absence of a catalyst, i.e., in the absence of a catalyst. Furthermore, the reforming process can be carried out in a single reformer or in multiple reformers, for example, in a pre-reformer and a secondary or primary reformer.

[0054] For its effective utilization in the blast furnace, the produced syngas needs to be of high quality. This quality is typically described by its reduction potential, defined by the following molar ratio: (cCO + cH₂) / (cH₂O + cCO₂). To ensure sufficient syngas quality, the reduction potential should be as high as possible, preferably higher than six, more preferably higher than seven, and most preferably higher than seven.5.

[0055] Thermodynamically, a certain reduction potential for syngas can only be achieved by applying a minimum temperature level to the reforming process. The reforming process is preferably carried out at a sufficiently high temperature that allows the syngas stream to have both the desired reduction potential and the temperature necessary for it to be fed through the blast furnace shaft. In embodiments where an H2 stream is added upstream of the reformer to the hydrocarbon-containing gas and / or blast furnace gas stream, the hydrogen addition helps reduce soot formation in the reformer and in the duct leading from the reformer to the blast furnace to feed the syngas through the blast furnace shaft.

[0056] Additionally, before the blast furnace gas stream is fed to the reformer, the blast furnace gas stream may advantageously undergo gas cooling and / or cleaning and / or pressurization steps, preferably steam removal steps, dust removal steps, metal removal steps, HCl removal steps and / or sulfur component removal steps.

[0057] In embodiments, the second stream of blast furnace gas can be used alone in the burners of the remodeling facility or in a mixture with other gases. In a preferred embodiment, as much blast furnace gas as possible is collected from the blast furnace for its use in the Cowper furnace and the remodeling facility. In other words, as little blast furnace gas as possible is supplied to other units within the steel plant. Preferably, it is so low that its use in thermal power facilities is avoided.

[0058] The term "fluid connection" refers to the connection between two devices via a conduit or pipe, allowing a fluid (e.g., gas) to flow from one device to the other. This term includes means for altering the flow, such as valves or fans for regulating mass flow, compressors for regulating pressure, and control elements, such as sensors and actuators, which are necessary or desirable for proper control of the blast furnace operation as a whole or the operation of each component within the blast furnace equipment.

[0059] In this article, "reformer" refers to any container in which a recombination process can be carried out, such as a recombination reactor or recombination container.

[0060] "Body feeding", "body injection", "feeding ... to the shaft of the blast furnace", "feeding ... at the shaft level", "feeding ... through the shaft", "feeding ... at the shaft level", "injected ... at the shaft level", or "gas inlet in the shaft" refers to the injection of material (such as, for example, gas) into the gas-solid reduction zone of ferrous oxide above the hot blast level (i.e., above the belly of the furnace), preferably above the softening zone in the blast furnace.

[0061] "Feeding ... at the tuyere level", "Feeding ... through the tuyere", "Feeding at the tuyere level" or "Injected at the tuyere level" means injecting material (such as, for example, gas) through the tuyere of the blast furnace.

[0062] In this article, “feeding to the blast furnace” and “injection into the blast furnace”, as well as “feeding to the blast furnace” and “injection into the blast furnace” or “injection into the blast furnace” are used as synonyms and have the same meaning, which means injecting material into the blast furnace.

[0063] In the context of this article, "or" is not exclusive, and either means "or" or "and".

[0064] In the context of this document, "about" means that a given value covers a range of values ​​from -10% to +10%, preferably from -5% to +5%.

[0065] In this document, step (c) generally refers to recombination. It encompasses the generation of syngas for injection through the furnace or tuyeres, as well as the generation of syngas for injection through both the furnace and tuyeres simultaneously.

[0066] Other details and advantages of this disclosure will become apparent from the following detailed description of several non-limiting embodiments, with reference to the accompanying drawings. Simple Explanation of the Diagram

[0067] Preferred embodiments of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which: [Figure 1] is a schematic diagram of an embodiment of a first variant of a blast furnace facility configured to implement this blast furnace operation method; [Figure 2] is a schematic diagram of an embodiment of a second variant of a blast furnace facility configured to implement this blast furnace operation method; [Figure 3] is a schematic diagram of an embodiment of a third variant of a blast furnace facility configured to implement this blast furnace operation method; and [Figure 4] is a graph showing the concentration of C2H4 in the recombination unit as a function of temperature for various hydrogen contents. Implementation

[0068] CO2 emissions:

[0069] Coke is the primary energy input in blast furnace ironmaking. From a CO2 perspective, and often also from an economic perspective, it is a less favorable energy source. Other energy sources are widely used to replace coke, primarily through injection at the tuyeres. Due to cost reasons, pulverized coal is mainly injected, but in countries with low natural gas prices, natural gas is used instead. Waste materials such as waste plastics are also commonly injected into the blast furnace. To reduce greenhouse gas emissions, industrial operations have begun to incorporate hydrogen as an auxiliary fuel, and with anticipated higher hydrogen availability, its contribution as an auxiliary fuel is expected to increase significantly.

[0070] These auxiliary fuels can have a positive impact on CO2 emissions from blast furnace steelmaking, but their use is limited by process considerations, and these limitations are generally now in place. Blast furnaces produce blast furnace gas (BFG), which contains up to approximately 40% of the energy input to the furnace. About 25% of the BFG leaving the blast furnace is typically used in the Cowper plant to heat the blast air injected at the tuyeres. The remaining 75% of the BFG, containing approximately 30% of the energy input to the blast furnace, is typically used for internal heating needs within the steel plant, but is also used for electricity production.

[0071] To reduce the CO2 footprint of blast furnace-based steel production, an important strategy is to use the BFG for metallurgical purposes as much as possible and to apply other CO2-poor energy sources, such as green electricity, to meet the steel plant's surplus energy needs.

[0072] Therefore, in addition to utilizing lean CO2 hydrocarbons, syngas production should make as much use of blast furnace gas as possible to increase the CO2 emission reduction potential from blast furnace ironmaking, and, if feasible in blast furnace facilities, increase the CO2 emission reduction potential from converter gas and / or cold basic oxygen furnace (BOF) gas.

[0073] Hydrogen utilization in iron smelting:

[0074] Hydrogen utilization in ironmaking can be divided into direct utilization of hydrogen in the blast furnace and utilization of hydrogen in auxiliary facilities, particularly the Cowper furnace facility and (if installed) a recombination facility for generating syngas to be injected into the blast furnace.

[0075] Hydrogen utilization in a blast furnace is commonly referred to as eta H2. eta H2 is defined as: eta H2 = ((H2 in the BF) – (H2 leaving the BF in the top gas)) / (H2 in the BF). In this paper, BF refers to the blast furnace, therefore (H2 in the BF) refers to the H2 stream entering the blast furnace, and (H2 leaving the BF in the top gas) refers to the H2 stream in the blast furnace top gas exiting from the top of the blast furnace.

[0076] "H2 in BF" is defined as the total hydrogen content of the belly gas (i.e., the gas in the blast furnace softening zone) and the blast furnace gas injected into the blast furnace at the blast furnace level. This hydrogen injected into the blast furnace specifically includes the hydrogen contained in the syngas, the injected molecular hydrogen H2, other hydrogen-containing gases, the injected coal and / or tar, the injected gaseous and solid fuel moisture, and the hot blast moisture.

[0077] "H2 leaving the blast furnace in the top gas" is defined as the dry flow rate of the top gas leaving the blast furnace multiplied by the dry concentration of hydrogen in the top gas.

[0078] Eta H2 is typically below 50%, and usually below 45%. Eta H2, and therefore the percentage of hydrogen utilized in the blast furnace, also exhibits a decreasing characteristic with increasing amounts of hydrogen input into the blast furnace. This means that when more hydrogen is desired to be used in the blast furnace, its utilization efficiency is significantly reduced, and a much larger portion of the hydrogen introduced into the blast furnace leaves with the top gas. Consequently, the achievable coke yield per kilogram of injected hydrogen also decreases, which indirectly reduces the CO2 reduction potential of the injected hydrogen.

[0079] Furthermore, when the injection of auxiliary fuel (i.e., hydrogen-containing gas) is increased, oxygen enrichment must be enhanced to maintain flame temperature. Increasing oxygen enrichment in the blast furnace means reducing the amount of natural blast (air) used in the blast furnace. As a result, the total amount of hot blast entering the blast furnace is reduced. This means less blast furnace gas can be used to heat the hot blast.

[0080] This ultimately means that when the percentage of hydrogen used to reduce iron ore in the blast furnace is increased, a smaller portion of that hydrogen is used inside the blast furnace and a smaller portion is used in the Cowper furnace facility, resulting in an increase in the amount of hydrogen leaving the blast furnace facility in the outlet gas.

[0081] This is illustrated in the table below (Table 1), which compares the operation of a control blast furnace with the operation of a blast furnace having hydrogen injection according to three embodiments of the method according to the present invention. [Table 1] serial number unit Reference Case 1: H2 injection Scenario 2: H2 injection + furnace syngas Scenario 3: Maximum H2 injection + furnace syngas 1 Iron (HM) production t HM / h 300 300 300 300 2 Coke yield t / h 90.3 87.12 67.35 63.03 3 Pulverized coal injection t / h 57.6 57.6 57.6 57.6 4 Natural gas used in syngas production Nm 3 / h 0 0 9993 9993 5 H2 injection at the air vent Nm 3 / t HM 38 38 109 6 Syngas injection at the blast furnace body Nm 3 / h 120000 120000 7 The syngas injected into the furnace contains H2. Nm 3 / h 61963 64485 8 H2 in the furnace belly gas Nm 3 / h 30322 41520 41062 60821 9 Total H2 Nm 3 / h 30322 41520 103025 125306 10 H2 leaving the furnace top gas Nm 3 / h 15901 21860 62053 76261 11 Eta H2 (H2 utilization in blast furnace) 47.6% 47.4% 39.8% 39.1% 12 Top gas energy GJ / h 1469531 1475909 1978421 2057046 13 Heat demand of hot blast furnace facilities GJ / h 541180 494746 392866 313884 14 Syngas reactor top gas demand GJ / h 575753 654788 15 Top gas outlet GJ / h 928351 981163 1009801 1088374 16 H2 Exit Nm 3 / h 10045 14532 31672 40349 17 H2 export ratio 33% 35% 31% 32% 18 H2 utilization in blast furnace facilities 67% 65% 69% 68% 19 CO2 emissions from coke, pulverized coal, and natural gas t / h 0 0 0 0

[0082] In the baseline operation, the blast furnace is injected with coke and pulverized coal only at the tuyere, while in Case 1, cold hydrogen is additionally injected at the tuyere level of the blast furnace.

[0083] As seen in Case 1, the hydrogen input to the blast furnace increased by 11.198 Nm³ / h from 30.322 Nm³ / h (control) to 41.520 Nm³ / h (Case 1), and the proportion of hydrogen exiting the blast furnace facility increased by 4.487 Nm³ / h from 10.045 Nm³ / h (control) to 14.532 Nm³ / h (Case 1). This resulted in a decrease in hydrogen utilization in the blast furnace facility from 67% to 65%. In other words, the 4.487 Nm³ leaving the blast furnace facility in the top gas accounts for 40% of the 11.198 Nm³ of additional injected hydrogen, therefore the utilization of the additional hydrogen in the blast furnace is much lower, at only 60%.

[0084] In scenario 2 (Table 1), hot syngas at 950°C was injected into the blast furnace. It can now be seen that although the total amount of hydrogen injected into the blast furnace was more than three times that of the control, its utilization in the blast furnace facility increased from 67% to 69%. This is very impressive because it shows that adding only a small amount of hydrogen at the tuyeres level has already had an impact on reducing hydrogen utilization in the blast furnace facility. Compared to the control, of the additional 72.703 Nm³ of hydrogen injected, only 21.627 Nm³, or 30%, left the blast furnace facility with the outlet gas.

[0085] In the last case (case 3) shown in Table 1, the amount of hydrogen entering the blast furnace increased significantly, more than four times that of the control case. Even now, it can be seen that hydrogen utilization within the blast furnace facility is higher than in the control case. Of the additional 94.984 Nm³ of hydrogen injected, only 30.304 Nm³, or 32%, left the blast furnace facility with the outlet gas.

[0086] Energy efficiency

[0087] To achieve high overall process efficiency, the Cowper furnace facility and the reheating facility should preferably be equipped with heat recovery systems for preheating combustion air and / or combustion gases. The efficiency of both facilities should be higher than 70%, more specifically higher than 80%.

[0088] Recombination and syngas requirements:

[0089] The requirements for syngas used in blast furnaces differ from those for applications in other industries.

[0090] The main requirements for the utilization of syngas in blast furnaces are as follows:

[0091] The reduction potential and temperature level of the synthesis gas:

[0092] In other industries, syngas is typically produced and then cooled to separate excess vapor from it. Therefore, only the cooled gas is used in downstream processes. In existing industrial applications outside the steel industry, achieving a high reduction potential directly through the recombination process is therefore not important. However, in the steel industry, a high reduction potential (preferably as high as possible and at least above 6) is preferred and highly advantageous for high process efficiency. The reduction potential, or reduction degree, is defined as: (cCO + cH₂) / (cH₂O + cCO₂), where c represents the molar concentration, such as, for example, cCO representing the molar concentration of CO in the syngas, cH₂ representing the molar concentration of H₂ in the syngas, cH₂O representing the molar concentration of H₂O in the syngas, and cCO₂ representing the molar concentration of CO₂ in the syngas.

[0093] Furthermore, a high temperature of the syngas is advantageous and appropriate for the temperature level required for injection through the tuyeres and / or through the furnace body to achieve maximum thermal efficiency. Therefore, the temperature should be between 850°C and 1100°C, preferably about 950°C, to allow its injection in the furnace body above the softening zone of the blast furnace (i.e., at the furnace body level).

[0094] H2 / CO ratio:

[0095] In industries other than steel, syngas is also used for specific applications such as the production of pure hydrogen, ammonia, or other chemical components. Therefore, a specific ratio of hydrogen to CO in the syngas is typically required.

[0096] In contrast, the purpose of using syngas in a blast furnace is to reduce the ore, which is achieved through two reducing components (CO and hydrogen). Although there is a difference between reducing the ore with CO or hydrogen, this difference is relatively small considering that syngas is only one part of the reducing gases used in the blast furnace.

[0097] Stress level:

[0098] While the pressure levels of reformers are relatively high in other industries, mostly above 20 barg or even above 40 barg, in blast furnace applications, the required pressure levels are only 1.5 barg to 6 barg. This has a significant impact on the operating conditions and limitations of reforming equipment, such as soot formation and equilibrium conversion. Although lower pressure levels will favor higher methane conversion at the same temperature level, unfortunately, this also favors soot formation. For this reason, adding H2 stream upstream of the reformer to the blast furnace gas stream and / or to hydrocarbon-containing gases is particularly beneficial in partially suppressing soot formation, even though this simultaneously reduces methane conversion at a given temperature compared to not adding hydrogen.

[0099] Hydrogen addition:

[0100] As shown above, hydrogen can be simply added at the blast furnace tuyeres in the form of H2, as well as in the form of hydrocarbons. However, it is also possible to use hydrogen addition to positively impact syngas production and its injection into the blast furnace body.

[0101] Adding a hydrogen stream, preferably renewable hydrogen, particularly before the reformer to reduce soot formation, or after the reformer to add it to the syngas stream injected through the furnace body to simultaneously cool it and increase its reduction potential. In this document, and when referring to syngas, reduction potential and degree of reduction are used synonymously and both refer to the molar ratio (cCO + cH₂) / (cH₂O + cCO₂). Heating the hydrogen stream before adding it upstream of the reformer is beneficial.

[0102] Due to the recombination reaction in syngas production:

[0103] Hydrocarbon gas reforming, such as natural gas reforming, can mainly be achieved through the following reactions:

[0104] Steam recombination in the presence of steam: CH4 + H2O = CO + 3H2

[0105] Dry recombination in the presence of CO2: CH4 + CO2 = 2CO + 2H2

[0106] Both of these reactions are strongly endothermic and require a large amount of heat.

[0107] The heat can be provided indirectly by burning fuel gases and transferring the heat from the flue gas to the reactor, or it can be provided by combining the recombination reaction with a partial oxidation reaction according to the following formula:

[0108] CH4+ ½CO2→ CO + 2H2

[0109] Along with the recombination reaction, side reactions can occur in the recombination reactor. The relative importance of these reactions depends on operating conditions such as gas composition, temperature and pressure, and the use and properties of the catalyst. The main side reactions at temperatures close to the recombination temperature are:

[0110] Reverse water gas shift reaction (RWGS): CO 2 + H 2 → CO + H 2O

[0111] CH4 decomposition: CH4 → C + 2H2

[0112] Methanation reactions: 4H₂ + CO₂ → CH₄ + 2H₂O or 3H₂ + CO → CH₄ + H₂O

[0113] And numerous reactions that fall under the category of reaction schemes for the formation of soot / carbon deposits. A typical example of these reactions is the formation of acetylene, as shown below:

[0114] Formation of acetylene: 2CH₄ → C₂H₂ + 3H₂

[0115] Then, the acetylene can form molecules (precursors) of aromatic hydrocarbons, which are part of the soot or can be thermally decomposed according to the following reaction:

[0116] Decomposition of acetylene: C₂H₂ → 2C + H₂

[0117] Hydrogen is a major component of these reactions and therefore has a significant impact on the recombination reaction itself as well as on side reactions. It is therefore possible to further improve the hydrocarbon recombination process by utilizing hydrogen in the blast furnace for the purpose of reducing CO2, such as to reduce soot formation and deposition, by adding H2 to the blast furnace gas stream and / or hydrocarbon-containing gases upstream of the recombinator.

[0118] Below, with reference to the accompanying drawings, are three different variations of the methods and facilities for operating a blast furnace.

[0119] Figure 1 illustrates an embodiment of a first variation of the method for operating a blast furnace, including the simultaneous injection of a first syngas flow through the blast furnace body and the injection of a second syngas flow through the blast furnace tuyeres.

[0120] Blast furnace gas 10 is collected at the top of blast furnace 12.

[0121] The collected blast furnace gas 10 is typically pretreated upon exiting the blast furnace. Pretreatment of the blast furnace gas stream includes initial cooling to reduce its vapor content; cleaning, particularly removing dust and / or HCl and / or metal compounds; and then pressurization to a pressure sufficient for final desulfurization, heating, remodeling processes, and injection into the blast furnace. In the embodiment of Figure 1, the cooling, cleaning, and pressurization of the blast furnace gas occurs in a cooling, cleaning, and pressurization unit 14. Alternatively, separate units may be used, each performing any one of the cooling, cleaning, or pressurization of the blast furnace gas. In other embodiments, one unit may be responsible for two of the cooling, cleaning, and pressurization of the blast furnace gas, with a third pretreatment step performed in a separate unit. Throughout this document, the cooling, cleaning, and pressurization unit is configured to cool, clean, and pressurize the gas stream, without assuming that multiple steps (cooling, cleaning, and pressurization) must be performed in this order. In embodiments, pressurization may occur upstream of cleaning, such as, for example, in an embodiment where the cleaning of the gas stream is desulfurization.

[0122] Downstream of the cooling, cleaning, and pressurizing unit 14, the blast furnace gas stream is divided into three streams. A first blast furnace gas stream 16 is fed to a first re-reforming facility 18, and a second blast furnace gas stream 20 is fed to a second re-reforming facility 22. In this embodiment, both re-reforming facilities are regenerative re-reforming facilities. A third blast furnace gas stream 27, referred to as blast furnace outlet gas, corresponds to the blast furnace gas fed to another unit of a steelmaking facility, which includes a blast furnace with re-reforming facilities 18 and 22.

[0123] Additionally, coke oven gas and / or natural gas stream 24 is supplied to reorganization facilities 18 and 22.

[0124] Alkaline oxygen furnace gas and / or steam may optionally be added to the blast furnace gas stream (upstream and / or downstream of cooling, cleaning and pressurizing unit 14) and / or hydrocarbon-containing gas stream 24 and / or directly added to the reorganization facilities 18, 22 (not shown).

[0125] In the first recombining facility 18, a first blast furnace gas stream 16 is recombined with a coke oven gas and / or natural gas stream 24 to produce a first syngas stream 26. In the recombining facility 22, a second blast furnace gas stream 20 is recombined with a coke oven gas and / or hydrocarbon-containing gas stream 24 to produce a second syngas stream 28.

[0126] The two recombination processes are dry and / or wet recombination processes, possibly combined with partial oxidation, resulting in the formation of two syngas streams 26 and 28 with high CO and H₂O contents. The recombination processes occur at pressures between 1.5 barg and 10 barg, and, depending on the recombination facility, at temperatures above 900°C, preferably above 950°C, and more preferably above 1000°C.

[0127] Blast furnace gas and / or hydrocarbon-containing gases may optionally be heated (not shown) prior to the reorganization process. Heating can be achieved, for example, by using a tube bundle heat exchanger. A second synthesis gas stream 28 exiting the second reorganization facility 22 is fed into the blast furnace through tuyeres 30 at a temperature of approximately 1200°C and a pressure of 2 to 6 barg.

[0128] Additionally, the blast furnace equipment includes an electrolysis cell 32 fueled by electricity 34 to generate H2 stream 36 through electrolysis (preferably by water / steam electrolysis). The electricity 34 that fuels the electrolysis cell 32 is preferably renewable or "green," i.e., obtained from renewable resources such as wind, solar, and / or hydropower.

[0129] Alternatively or additionally, the hydrogen can be produced from natural gas via a pyrolysis process with solid carbon formation or with a combination of carbon capture and storage (CCS) and / or carbon capture and utilization (CCU) technologies. Hydrogen can also be produced via methane thermal cracking or steam methane reforming with a combination of CCS and / or CCU technologies.

[0130] The H2 stream 36 generated by the electrolyzer is added downstream of the first recombining facility 18 and upstream of the gas inlet 38, which is configured to pass through the furnace body within the blast furnace 12, to the first syngas stream 26. The first syngas stream 26 with added hydrogen 36 forms an H2-rich gas stream 40, which is fed into the blast furnace through the gas inlet 38 at the furnace body level, at a temperature of approximately 900°C and typically at a pressure of 1.5 barg to 4 barg.

[0131] H2 stream 36 acts as a coolant for the first syngas stream 26. Using the hydrogen in this way (i.e., as a coolant) completely eliminates the need to heat the hydrogen in an expensive heating unit before injecting it through the furnace body of blast furnace 12. In effect, the excess heat of the syngas 26 heats the hydrogen. This allows for increased process efficiency by eliminating both the need for syngas cooling and hydrogen heating.

[0132] Figure 2 illustrates an embodiment of a second variation of the method for operating a blast furnace, including the simultaneous injection of a first syngas flow through the blast furnace body and the injection of a second syngas flow through the blast furnace tuyeres.

[0133] Blast furnace gas 110 is collected at the top of blast furnace 112.

[0134] The collected blast furnace gas 110 is typically pretreated upon exiting the blast furnace. Pretreatment of the blast furnace gas stream includes initial cooling to reduce its vapor content; cleaning, particularly removing dust and / or HCl and / or metal compounds and / or sulfur components; and then pressurizing it to a pressure sufficient for the repackaging process and its injection into the blast furnace. In the embodiment of Figure 2, the cooling, cleaning, and pressurization of the blast furnace gas occur in cooling, cleaning, and pressurization unit 114. Alternatively, separate units can be used, each performing any one of the cooling, cleaning, or pressurization of the blast furnace gas. In other embodiments, one unit may be responsible for two of the cooling, cleaning, and pressurization of the blast furnace gas, with the third pretreatment step performed in a separate unit.

[0135] Downstream of the cooling, cleaning, and pressurizing unit 114, the blast furnace gas flow is divided into three streams. A first blast furnace gas flow 116 is fed to a first re-reforming facility 118, and a second blast furnace gas flow 120 is fed to a second re-reforming facility 122. In this embodiment, both re-reforming facilities are regenerative re-reforming facilities. A third blast furnace gas flow 127, referred to as blast furnace outlet gas, corresponds to the blast furnace gas fed to another unit of a steelmaking facility, which includes a blast furnace with re-reforming facilities 118 and 122.

[0136] Additionally, in addition to the blast furnace and cooling, cleaning, and pressurizing unit 114, the blast furnace equipment also includes a source of coke oven gas and / or natural gas streams 124 in fluid communication with each of the recombining facilities 118, 122, and an electrolyzer 132 fueled by electricity 134 to generate H2 stream 136 by electrolysis (preferably by water electrolysis). The electricity 134 fueling the electrolyzer 132 is preferably renewable or "green," i.e., obtained from renewable resources such as wind, solar, and / or hydropower.

[0137] The H2 stream 136 generated by the electrolyzer is added upstream of the reorganization facilities 118 and 122 to the coke oven gas and / or natural gas stream 124 to form an H2-rich hydrocarbon gas stream 142, which is then fed to each of the reorganization facilities 118 and 122.

[0138] Alkaline oxygen furnace gas and / or steam may optionally be added to the blast furnace gas stream (upstream and / or downstream of cooling, cleaning and pressurizing unit 114) and / or to the hydrocarbon-containing gas stream 124 and / or to the H2 stream 136 and / or directly to the recombining facilities 118, 122 (not shown).

[0139] In the first recombining facility 118, the first blast furnace gas stream 116 and the H2-rich hydrocarbon-containing gas stream 142 are recombined to produce the first syngas stream 126. In the second recombining facility 122, the second blast furnace gas stream 120 and the H2-rich hydrocarbon-containing gas stream 142 are recombined to produce the second syngas stream 128.

[0140] Both recombination processes are dry recombination, resulting in the formation of two syngas streams 126 and 128 with high CO and H₂O contents. The recombination processes occur at pressures between 1.5 barg and 10 barg, and, depending on the recombination facility, at temperatures above 900°C, preferably 1000°C, and more preferably above 1200°C.

[0141] Blast furnace gas and / or hydrogen-containing gas may optionally be heated (not shown) prior to the reorganization process. Heating can be achieved, for example, by using a tube bundle heat exchanger.

[0142] Adding hydrogen upstream of reorganizing facilities 118 and 122, and thus prior to the reorganizing process, will help reduce soot formation during the reorganizing reaction. Carbon deposition formed by dry reorganizing is a known problem. Various reactions occur within the reorganizing facility and lead to the formation of carbon deposits. Many of these reactions include the formation of ethylene (C₂H₄) and acetylene (C₂H₂) precursors. The formation of these precursors from methane results in hydrogen separation and an increase in gas volume. Therefore, it is possible to reduce the formation of carbon deposit precursors and thus the formation of carbon deposits themselves by increasing the partial pressure of hydrogen in the reactor inlet gas, which means adding H₂ to the gas mixture to be reorganized, such as by adding H₂ to the hydrocarbon-containing gas and / or to the synthesis gas stream. For example, as shown in Figure 4, increasing the amount of H₂ in the gas mixture to be reorganized from 10% to 40% resulted in a significant reduction in the C₂H₄ concentration in the reorganizing facility, from approximately 0.35% at 1225°C to approximately 0%.

[0143] The first syngas stream 126, exiting the second recombining facility 118, is fed into the blast furnace 112 via a gas inlet 138 configured to pass through the furnace body (i.e., the second syngas stream 126 is fed through the furnace body), at a temperature of approximately 950°C and a pressure of 1.5 barg to 4 barg. Depending on the recombining process, the second syngas stream may be cooled to approximately 950°C before being fed through the furnace body.

[0144] The second synthesis gas stream 128, which exits the second recombining facility 122, is fed into the blast furnace through the tuyeres 130 at a temperature of about 1200°C and a pressure of 2 barg to 6 barg.

[0145] Figure 3 illustrates a third embodiment of the method for operating a blast furnace, which includes simultaneously injecting a first synthesis gas stream through the blast furnace body and injecting cold hydrogen and / or hydrocarbon-containing gas, and possibly also injecting pulverized coal through the blast furnace tuyeres.

[0146] Blast furnace gas 210 leaving blast furnace 212 is collected at the top of blast furnace 212.

[0147] The collected blast furnace gas 210 is typically pretreated in the gas cleaning and cooling unit 214 as it leaves the blast furnace. The pretreatment of the blast furnace gas stream includes initial cooling to reduce its vapor content; cleaning, particularly the removal of dust and / or HCl and / or metal compounds.

[0148] A portion 219 of the cleaned blast furnace gas, used as fuel, along with moist air 223 and typically other high-heat gases (not shown) in the burners of the Cowper furnace facility 221, is used to heat the blast air injected into the blast furnace at its tuyeres level. Both the gas and the air may be preheated or not.

[0149] Another portion 217 of the blast furnace gas is used as fuel, which is combined with moist air 223 and typically with other high-heat gases (not shown) in the burner of the reheating facility 218. Both the gas and the air may be preheated or not.

[0150] The additional blast furnace gas flow 216 is used in the reforming reaction. This flow is also fed to a compressor (pressurization unit) 215 to compress the blast furnace gas to the pressure level required for reforming and injection into the blast furnace.

[0151] The remaining blast furnace gas leaving blast furnace 212 that is not used for reorganization facilities or Cowper furnace facilities is called blast furnace outlet gas 227 and is supplied to other units within the steel plant, including blast furnace 212.

[0152] In the embodiment of Figure 3, a hydrogenation and desulfurization unit 250 may optionally be present after the compressor (pressurization unit) 215.

[0153] Additionally, coke oven gas and / or natural gas stream 224 is fed to reprocessing facility 218. Gas 224 can be desulfurized in desulfurization unit 250. Desulfurization of gas 224 can be carried out together with desulfurization of blast furnace gas (Figure 3). Alternatively, gas 224 can be desulfurized in a separate desulfurization unit (not shown). In such an embodiment, hydrogen can be added to natural gas to hydrogenate organic sulfur (not shown) contained in the natural gas.

[0154] Alkaline oxygen furnace gas and / or steam 225 may optionally be added to the blast furnace gas stream (upstream and / or downstream of pressurization unit 215), to hydrogenation and desulfurization unit 250, to hydrocarbon-containing gas stream 224 (not shown), and / or directly to reforming facility 218 or after reforming facility 224.

[0155] The recombining of blast furnace gas stream 216 with coke oven gas stream and / or natural gas stream 224 takes place in recombining facility 218 to produce syngas stream 226. The two gas streams, blast furnace gas 216 and hydrocarbon-containing gas, need to be mixed before entering recombining facility 218, within recombining facility 218, and / or before entering hydrogenation and desulfurization facility 250.

[0156] The recombination process is a dry and / or wet recombination process, possibly combined with partial oxidation, resulting in the formation of a syngas flow 226 with high CO and H₂O content. The recombination process occurs at pressures between 1.5 barg and 10 barg, and, depending on the recombination facility, at temperatures above 900°C, preferably above 950°C, and more preferably above 1000°C.

[0157] Blast furnace gas and / or hydrogen-containing gas may optionally be heated (not shown) prior to the reorganization process. This can be achieved, for example, by using a tube-bundle heat exchanger that transfers a portion of the heat from the flue gas of the reorganization facility. The same applies to gas mixtures comprising blast furnace gas and hydrocarbon-containing gases entering the reorganization facility, preferably also heated to at least 350°C, more preferably to above 400°C, and most preferably to above 450°C. Alternatively, blast furnace gas and air used in burners at the Cowper furnace facility and / or the reorganization facility may also be heated to transfer a portion of the heat from the flue gas of the reorganization facility in a heat exchanger (e.g., a tube-bundle heat exchanger).

[0158] Additionally, the blast furnace equipment includes an electrolytic cell 232 fueled by electricity 234 to generate H2 stream 236 by electrolysis (preferably by water / steam electrolysis). The electricity 234 fueling the electrolytic cell 232 is preferably renewable or "green," i.e., obtained from renewable resources such as wind, solar, and / or hydropower.

[0159] Alternatively or additionally, the hydrogen can be produced from natural gas via a pyrolysis process with solid carbon formation or with a combination of carbon capture and storage (CCS) and / or carbon capture and utilization (CCU) technologies. Hydrogen can also be produced via methane thermal cracking or steam methane reforming with a combination of CCS and / or CCU technologies.

[0160] The H2 stream 236 or a portion thereof generated by the electrolyzer is added upstream of the reforming facility 218 to the coke oven gas and / or natural gas stream 224 to form an H2-rich hydrocarbon gas stream, which is then fed to the reforming facility 218, and / or partially fed to the hydrocarbon gas stream prior to the hydrogenation step, and / or fed at the tuyeres of the blast furnace, either alone or together with other auxiliary fuels (such as coal, natural gas, plastics, biomass, etc.), in a cooled manner.

[0161] Alkaline oxygen furnace gas and / or steam may optionally be added to blast furnace gas stream (upstream and / or downstream of pressurization unit 215 or hydrogenation unit 250) (not shown) and / or hydrocarbon-containing gas stream 224 (not shown) and / or added to H2 stream 236 (not shown) and / or directly added to reorganization facility 218 or added after reorganization facility 218.

[0162] A portion of the H2 stream 236 can be added to the syngas stream 226 downstream of the recombining facility 218 and upstream of the gas inlet 238, which is configured to pass through the furnace body within the blast furnace 212. The syngas stream 226, with hydrogen 236 added, forms an H2-rich gas stream 240, which is fed into the blast furnace through the gas inlet 238 at the furnace body level, at a temperature of approximately 900°C and typically at a pressure of 1.5 barg to 4 barg.

[0163] Some of the hydrogen 236 and / or hydrocarbon-containing gas 224 can also be injected directly through the tuyeres 230 of the blast furnace. In an embodiment, the injection of hydrogen 236 and / or hydrocarbon-containing gas 224 can be carried out together with the injection of solid fuel (such as, for example, pulverized coal injection 229).

[0164] A portion of the H2 stream 236 can be used as a coolant for the first syngas stream 226. Using the hydrogen in this way (i.e., as a coolant) completely eliminates the need to heat the hydrogen in an expensive heating device before injecting it through the furnace body of the blast furnace 212. In effect, the excess heat of the syngas 226 heats the hydrogen. This allows for increased process efficiency by eliminating the need for both syngas cooling and hydrogen heating.

[0165] Although the invention has been described in detail in the accompanying drawings and the foregoing description, such description should be considered illustrative or exemplary, not restrictive; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments will be understood and implemented by those skilled in the art when practicing the claimed invention by reading the drawings, the specification, and the appended claims.

[0166] 10, 110, 210: Blast furnace gas flow 12,112,212: Blast Furnace 14,114,214: Cooling, cleaning, and pressurization units 16,116,216: Gas flow from the first blast furnace 18,118,218: First Restructuring Facility 20,120: Second blast furnace gas flow 22,122: Second Reorganization Facility 24,124,224: Coke oven gas and / or natural gas streams 26,126,226: First synthesis gas flow 27,127,227: Blast furnace outlet gas 28,128: Second synthesis gas flow 30, 130, 230: At the tuyeres (horizontal) of the blast furnace 32,132,232: Electrolytic cell 34,134,234: Electricity 36,136,236:H 2 flow 38, 138, 238: Gas inlets through the blast furnace body 40,240: H2-rich synthesis gas flow 142: Hydrocarbon-containing gas stream rich in H2 215: Pressurization unit (compressor) 217: Blast furnace gas supplied to the burners of the reorganization facility 219: Blast furnace gas supplied to the burners of the Cowper furnace facility 221: Cowper Furnace Facilities 223: Humid air 225: Steam 229: Pulverized Coal 250: Hydrogenation and Desulfurization Unit

Claims

1. A method for operating a blast furnace, comprising the following steps: a. Collect blast furnace gas stream from a blast furnace having a furnace body and at least one tuyeres; b. Feeding the blast furnace gas stream and hydrocarbon-containing gas to a reforming facility including at least one reformer; c. Recombining the blast furnace gas stream and the hydrocarbon-containing gas in the recombination facility to generate a synthesis gas stream; and d. Feeding at least a portion of the synthesis gas stream to the blast furnace; wherein an H2 stream is added to the hydrocarbon-containing gas before step (c), and / or to the blast furnace gas stream before step (c), and / or to a mixture comprising the blast furnace gas and the hydrocarbon-containing gas before step (c), and / or to the synthesis gas stream before step (d); and wherein at least a portion of the synthesis gas stream is fed to the blast furnace through the furnace body.

2. A method for operating a blast furnace, the method improving the efficiency of hydrogen utilization in the blast furnace, the method comprising adding H2 to the blast furnace in conjunction with a recombination reaction; wherein, The hydrogen utilization portion in the blast furnace facility, which includes the blast furnace, reorganization facility, and Cowper furnace facility, is higher than 60% of the hydrogen fed to the blast furnace; wherein, the hydrogen utilization is defined as: (hydrogen input to the blast furnace facility – hydrogen output from the blast furnace facility) / (hydrogen input to the blast furnace facility); wherein, the hydrogen fed to the blast furnace is defined as the total hydrogen content of the gas in the melting zone of the blast furnace and the furnace gas injected into the blast furnace at the furnace body level, and the total amount of hydrogen fed to the blast furnace is a minimum of 200 Nm3 / t of produced molten iron, and wherein a minimum of 50 Nm3 / t of molten iron is fed to the blast furnace facility in the form of molecular hydrogen H2; wherein, the hydrogen input to the blast furnace specifically includes hydrogen contained in the syngas, injected molecular hydrogen H2, other hydrogen-containing gases, injected coal and / or tar, injected gaseous and solid fuel moisture, and hot blast moisture.

3. The method according to request item 1, wherein, At least a portion of the synthetic gas flow is fed to the blast furnace through the furnace body and through at least one tuyeres of the blast furnace.

4. The method according to request item 1, 2, or 3, wherein, At least a portion of the hydrogen supplied to the blast furnace facility is injected through at least one tuyere of the blast furnace.

5. The method according to request item 1, 2, or 3, wherein, At least a portion of the synthetic gas flow is fed to the blast furnace through the furnace body and through at least one tuyeres of the blast furnace.

6. The method according to request item 1, 2, or 3, wherein, The H2 stream is added to the synthetic gas stream at a temperature below 600°C.

7. The method according to request item 1, 2 or 3, wherein, The blast furnace gas stream and / or the hydrocarbon-containing gas stream are hydrogenated and / or desulfurized in the hydrogenation and desulfurization unit upstream of the reorganization facility.

8. The method according to request item 7, wherein, At least a portion of the hydrogen is added to the hydrocarbon-containing gas stream upstream of the hydrogenation and desulfurization unit.

9. The method according to request item 1, 2 or 3, wherein, The H2 flow is generated by electrolysis in the electrolytic cell.

10. The method according to claim 9, wherein, The electricity used to operate the electrolyzer is generated from renewable resources such as wind, solar and / or hydropower.

11. The method according to claim 1, 2, or 3, wherein, The hydrocarbon-containing gas includes natural gas, coke oven gas, and / or biogas.

12. The method according to request item 1, 2, or 3, wherein, The at least one recombiner in the recombination facility is a regenerative recombiner.

13. The method according to request item 1, 2, or 3, wherein, The at least one reformer in the reforming facility is any type of catalytic dry and / or wet reformer, particularly a bottom-burning, side-burning, platform-type, or top-burning reformer.

14. The method according to request item 1, 2, or 3, wherein, The recombination facility includes two recombinators, specifically a pre-recombiner and a main recombinator.

15. The method according to request item 1, 2, or 3, wherein, The recombination at step (c) is carried out non-catalytically.

16. The method according to request item 1, 2, or 3, wherein, The recombination at step (c) is combined with the partial oxidation of hydrocarbons.

17. The method according to request item 1, 2 or 3, wherein, The reduction potential of the synthesis gas generated in step (c) is higher than 6; wherein the reduction potential is defined by the molar ratio (cCO+cH2) / (cH2O+cCO2).

18. The method according to request item 1, 2 or 3, wherein, The recombination at step (c) is carried out at a temperature above 900°C.

19. The method according to claim 1, 2 or 3, wherein, Before the blast furnace gas stream is fed to the reformer, the blast furnace gas stream also undergoes gas cooling and / or cleaning and / or pressurization steps.

20. The method according to claim 1, 2 or 3, wherein, After the cleaning step, a steam stream is added to the hydrocarbon-containing gas and / or a steam stream is added to the blast furnace gas.

21. The method according to request item 1, 2, or 3, wherein, The blast furnace gas flow is used in the burner of the reorganization facility.

22. A blast furnace facility, comprising a blast furnace having a furnace body, a tuyer arranged for supplying a first hydrogen-containing gas stream to the blast furnace, and a gas inlet arranged in the furnace body for supplying a syngas stream to the blast furnace, the blast furnace facility further comprising: A recombining facility, the recombining facility comprising at least one recombiner connected to the top of the blast furnace and to a source fluid containing hydrocarbon gas, the recombiner being arranged to convert the blast furnace gas stream and the hydrocarbon gas into a synthesis gas stream, and the recombiner being connected downstream of the gas inlet fluid in the furnace body of the blast furnace; The source of H2 flow that is fluidly connected to the at least one reformer and / or to the gas inlet in the furnace body and / or the tuyeres of the blast furnace.

23. The blast furnace facility according to claim 22, wherein, The blast furnace facility is configured to implement a method for operating a blast furnace according to any one of claims 1 to 21.

24. The blast furnace facility according to claim 22 or 23, wherein, The reformer is connected downstream of the tuyeres of the blast furnace and to the gas inlet fluid in the furnace body.

25. The blast furnace facility according to claim 22 or 23, wherein, The reorganization facility includes a regenerator.

26. The blast furnace facility according to claim 22 or 23, wherein, The recombination facility includes catalytic dry and / or wet recombination units; and / or wherein the recombination facility includes two recombination units, particularly a pre-recombiner and a main recombination unit.

27. The blast furnace facility according to claim 22 or 23, wherein, The reorganization facility also includes a partial oxidation reactor.

28. The blast furnace facility according to claim 22 or 23, wherein, The arrangement of fluid connections between the blast furnace top and the blast furnace roof for conveying blast furnace gas flow to the reorganization facility also includes gas cooling and / or cleaning and / or pressurization facilities.

29. The blast furnace facility according to claim 22 or 23, wherein, The arrangement for conveying blast furnace gas flow to the reorganization facility, and the fluid connection to the top of the blast furnace, also includes a pressurization unit and / or hydrogenation and desulfurization facilities.

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